CA1120093A - Electrostatic copying process and apparatus - Google Patents

Abstract

ABSTRACT
The invention relates to an electrostatic copying apparatus of type in which an electrostatic latent image is developed on the surface of a photosensitive member by applying a fine powdery developer to the electrostatic latent image to form a toner image which is transferred to a receptor sheet after which the remaining electrostatic charge on the photosensitive member is eliminated and the photosensitive member cleaned of excess developer. The cleaning step is carried out, according to the invention, by magnetically holding the same developer as used in the developing step on the surface of a developer-holding member by means of a magnet disposed within the developer-holding member, moving the surface of the developer-holding member in a direc-tion opposite to the moving direction of the surface of the photosenstive member to contact the two surfaces at reasonable relative speeds through the layer of the developer, and thus mechanically brushing the surface of the photosensitive member by the layer of the developer.

Description

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This application is a divisional of copending Canadian Application Serial No. 301,377 filed April 18, 1978 in the name of Mita Industrial Company, Limited.
This invention relates to a process for electrostatic copying.
More specifically, it relates to an electrostatic copying process which com-prises a step of forming an electrostatic latent image corresponding to an original on a photosensitive member having a photoconductive layer and a developing step for rendering the latent image visible.
Generally, electrostatic copying processes for forming a copied image corresponding to an original include a step of forming an electrostatic latent image corresponding to an original on a photosensitive member having a photoconductive layer, and a developing step for rendering the electrostatic latent image visible. The electrostatic latent image-forming step comprises a step of applying an electrostatic charge to the photosensitive member and a step of projecting the original image on the photosensitive member. The electrostatic latent image formed on the photosensitive member in the latent image-forming step is rendered visible by developing it either directly or after transferring it to a suitable material ~latent image transfer). The developing step can be performed by varlous methods, but generally, it is performed by applying a fine powdery developer (toner~ to the electrostatic latent image.
Research and development have been done recently on various -~
aspects of these electrostatic copying processes, especially the electro-static latent image-forming step and the developing step, and various improvements have been suggested. None of them, however, are entirely satis-factory, and various problems still exist which have to be further solved to obtain copied images of better quality. In particular, the developing step performed by applying a fine powdery developer to the electrostatic latent image poses the many problems which are described in detail below with reference to the accompanying drawings.

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Extensive research and development have also been undertaken in recent years on the electrostatic copying apparatus for the performance of these electrostatic copying processes, and various improvements have been suggested. These apparatus, however, have to be improved further to obtain better copied images, permit easier operation and maintenance, and to render them simpler in structure and lower in price.
It is a primary object of this invention to provide an electro-static copying process in which a developing step to be performed by applying a fine powdery developer to an electrostatic latent image is improved.
According to the present invention, there is provided an electro-static copying process which comprises (1) a step of forming an electrostatic latent image on the surface of a photosensitive member having a photo-conductive layer, ~2) a step of developing the electrostatic latent image by applying a fine powdery developer to the electrostatic latent image to form a toner image on the surface of the photosensitive member, (3) a step of transferring the toner image by conveying a receptor sheet to a transfer station and successively contacting the surface of the photo-sensitive member closely with the surface of the receptor sheet in the ~-transfer station to transfer the toner image to the surface of the receptor sheet, (41 a step of fixing the toner image by separating tbe receptor sheet from the surface of the photosensitive member and fixing the toner image transferred onto the surface of the receptor sheet~ (5) a step of eliminating electrostatic charge by irradiating the surface of the photosensitive member with an electrostatic eliminating lamp after the toner image has been trans-ferred to the receptor sheet, and ~6) a step of cleaning the surface of the ~ -photosensitive member by removing the developer remaining on the surface of the photosensitive member after the electrostatic eliminating step; wherein the cleaning step (6) is carried out by magnetically holding the same developer as used in the developing step on the surface of a developer-holding member by means of a magnet disposed within the developer-holding , member, moving the surface of the developer-holding member in a direction opposite to the moving direction of the surface of the photosensitive member to contact the two surfaces at reasonable relative speeds through the layer of the developer, and thus mechanically brushing the surEace of the photo-sensitive member by the layer of the developer.
The invention will now be descrlbed in greater detail with reference to the acc~mpanying drawings, in which;
Figures l-a to l-c are simplified views for :

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illustrating a ghost image which occurs during develop--ment in a known rolling contact method;
Figure 2 is a simplified view of an electrostatic latent image~bearing member and a developing apparatus for illustrating the developing step in the electrostatic copy-ing process in accordance with this invention;
Figure 3 is an enlarged view of a part of a brush length adjusting member used in the developing apparatus shown in Figure 2;
Figure 4 is a dlagram showing suitable regions of distances dl and d2;
~: Figure 5 ls a simplified view o~ an electrostatic copying apparatus for illustrating the electrostatic copy-ing process in accordance with this invention;
: 15 Figure 6 is a simplified view ofan electrostatic : eliminator;
~: Figure 7 is a simplified view of an electrostatic : latent image~-bearing member and a cleanlng~device for il : lustrating a cleaning step in the electrostatic copying ~ ~ .
process in accordance with this ln~ention;
igure 8 is a perspective view9 partly broken ~: away, of the electrostatic copying apparatus ln accordance : with this invention; : ~
Figure 9 is a sectional view of the electrostatic ; 25 copying apparatus shown in Figure 8;
igure 10 is~a simplified partially perspective view showing an optical system;
Figure 11 is a perspective view, partly ~roken away, of an upper part of the electrosta-tic copying apparatus : -- 4 -'I .

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shown in Figure 8;
Figure 12 is a perspective view showing a support structure;
Figure lZ is a partial perspective view showing the state of a lower part of the electrostatic copying ap-paratus shown in Figure 8~ in which a support has been partly pulled out;
~ igure l~A is an exploded view showing a modified example of a support and elements moun-ted on it;
Figure 14 is a partial perspective view of that part of the electrostatic copying apparatus shown in Figure 8 on which the support is mounted;
~ igure 15 is a side elevation of that par-t of the apparatus on which a rotar~ drum is mounted;
Figure 16 is a partial perspective view of a paper feed section;
Figure 17A and ~igure 17B are front elevatlons of the paper feed section shown in Figure 16;
~ igure 18 is a `simplified view showlng a drive system; :
Figure 19 is a simpli.fied partlal perspective view for illustrating the drive system; ~:
igure 20 is a slmplifled view showlng electrical elements of the electrostatic copying apparatus shown in ~ 25 Figure 8;
;~ Figures 21 to 24 are circuit diagrams showing the wire bonding of the electrical elements of the electro-static copying apparatus shown in Figure 8; and Flgure 25 is a partial perspective vieW showing - 5 ~

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zo~93 a mechanical sensing element which may be provided to register the forward end of an original optically pro-jected on the surface of the rotar.y drum with the forward end of a receptor sheetO
DE~I ED DESCRIP ON O _PXEFERRED ~MBODIMENTS
~he present inven-tion is described in detail with reference to the accompanying drawingsO
~,e ro~ ~c, cop~,,n~ m~t~hod Electrostatic copying processes for forming a copied image corresponding to an original image~ as is well known, include a xerographic process9 an electro-fax pro-cess~ or a ~ESI process including an electrostatic latent image transferring stepO All of these processes commonly include a step of forming an elec-trostatic latent image corresponding to an original image on a photosensitive member having a photoconduc-tive layer, and a developing step for rendering the electrostatic latent image visible~
Develo~a~ eP
; ~he developing step for rendering the electrostatic latent image visible can be performed by various known de-veloping methods~ In recent years, a method involving the application of a fine powdery developer (toner) to the :~ electrostatic latent image to be developed has been pre-ferredO
One typical known method within this category comprises magnetically holding a fine powdery developer on the surface of a developer-holding member in the form of a hollow cylindrical sleeve or an endless belt by means of a magn~t disposed within the developer-holding member, ~ 6 --.,, ;

and then contacting the surface of the developer-holding member with the surface of an image-bearing member having an electrostatic latent image formed thereon (i.e., a photo-sensitive member or a receptor member to the surface of which the electrostatic latent image has been transferred) through the developer, thereby to apply the developer to the electro-static latent image.
It was first suggested with regard to this known method to move the surface of the developer-holding member and the surface of the latent image-bearing member in opposite directions to each other, thereby successively contacting the two surfaces with each other. According to the suggestion, however, the density of the image is low because of a fairly great slippage between the two surfaces (the difference in moving speed), and the image obtained is unsatisfactory with a poor resolving power and a poor reproducibility of halftone.
In an attempt to overcome this disadvantage, a ~ :
"rolling contact method" was suggested which comprises moving the surface of the developer-holding member and the surface of the electrostatic latent image-bearing member in the same direction at the same speed, thereby contacting - -the two surfaces successively without substantial slippage (for example, United States Patent No. 4,081,571 which issued ~arch 28, 1978, or British Patent~1,493,28Q~. This rolling contact method can afford an image which has a suit-able image density, a high resolving power, and a good reproducibility of halftone. If a mono-component developer (so-called carrierless developer) composed of one kind of magnetic fine powder is used in this rolling contact ,, , , ~ .

)93 method, the developer adheres -to the surface of the latent lmage~bearing member too faithfully according to the po~
tential on the surfaceO ~his causes the following dis~
advantages that must be overcomeO
(i) l1he developer adheres thinly to an area which is spaced from the image area by some distance to form a so-called ghost image or fringed imageO
(ii) The developer adheres thinly to the back-. ground area of the image to cause background fogging.
~he ghost image formation and the background fog-ging are described in detail below with reference to Fig-ures l-a and l - Co .An electrostatic latent image formed on the surface of electrostatic latent image~bearing member

2 has at its image area I a charge and a potential of a ; 15 specific polarity (for example, positive), and because of the edge e~fect of the charge on the lmage area, a potential of an opposite polarity (for example9 negatlve) in the ~ surrounding of the lLage areaO Accord1ngl~j t~e p-)tential : pattern of the electrostatic image shown in Figure l-a is known to be as shown in Figure l--bo If the developer com-posed of a single magnetlc fine powder lS caused to ap-proach the electrostatic latent image9 the charge of the ~:~ electrostatic latent image induces a charge of an opposite polarity in the developer, and therefore, the development of the latent image proceeds by the Coulomb's attractive force acting between the two chargesO Since the developer is magnetically :held on th.e surface of the developer-hold-ing member, the developer, upon cDntact with the electro--static latent image, adheres to that part of the latent : , . .. .
, image which has a potential above a certain value (1 y V) that begins to exert a Coulomb's attractive force larger than the magnetic holding force of the developer--holding member on the developer, irrespective of the polarity of the potential on that partO Thus, when the surface of the electrostatic latent imagewbearing member is contacted successively with the developer from right to left in ~igure l-a (in the direction shown by arrOw A in ~i.gure l--a), the developer adheres to the portion of image area I, and thinly to part G which is upstream of the image area by distance xO Consequently, as shown in ~igure l-c 7 a ghost image is formed at part G upstream of image area Io A potential above the certain value (+ y V) exists on part G',sp~ced downstream of the image area I by distance x until the development of image area I endsO When the de-velopment proceeds and the potential of the latent image in image area I decre~ses as a result of the adhesion of the developer to image area I, the potential on part G' de-: creases to below + y V, and therefore, a ghost image does not sub~tantially form on part Gl downstream of the image area O
In an ordinary electrostatic copying process in which an electrostatic latent image formed on a photosensitive ,:
member is directly developed, the photosensitive member is fatigued as a result of forming an electrostatic latent imagein the previous cycle, and it is extremely difflcult, if not impossible 9 to remove the fatigue completely before the beginning of the new cycleO Accordingly, the photo-sensitive member (iOeO, the electrostatic latent image-.. . ..
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` - l~ZO~g3 bearing member) has some residual potential caused by the fatigue in the previous cycle in addition to the potential of the electrostatic latent image to be developedO Gene-rally9 the residu~l potential tends to lncrease gradua~.ly as a result of repeatedly using the photosensitive member with a short recess between cyclesO In the case of using an ordinary two--component developer9 the developer is biased to a specified potential of the same polarity as the residugl potential and thus cancels the residual po~
: 10 tentialO In contrast9 in the rolling contact method9 the developer adheres to the surface of the electrostatic latent image~bearing member too faithfully according to the surface poten-tial of the image bearing member9 and in particular9 a mono--componen-t developer is attracted by a potential of any of the positlve and negative polaritiesO
Hence9 if a bias voltage is applied9 the adhesion of the : developer is increasedO Mainly for the above reason9 the developer adheres also to an area having the residual po-: tential9 and the background fogging of the non~-image area ;~ 20 gradually increases as the number of copying operations ncreasesO
~he present inventors have newly found that if the surface of the developer--holding member and the surface of the electrostatic latent image-bearing member are con-tacted with each other successively by being moved in the same direction at somewhat different speeds in a developing station. where the surf&ce of the developer holding member is contacted with the image~-bearing member through the developer9 the developer which adheres weakly to the - 10 ~-: ~ . . .. . .

, ~lZ~9 surface of the image--bearing member and causes ghost image formation and background fogging can be wiped off by exerting the mechanical brushing action on the developer held magnetically to the surface of -the developer-holding member without reducing the density and resolving power of the image and -the reproducibility of halftone; and -that consequently9 the desired image free from ghost image for-mation and background fogging can be obtainedO
Specifically9 the present inventors have newly found that in an electrostatic la-tent image developing process which comprises magnetically holding a fine powdery developer on the surface of a developer holding member by means of a magnet disposed within the developer-holding member9 then contacting the surface of the developer--holding member with the surface of an elec-trostatic latent image-bearing member through the developer9 and thus applying the developer : to the electrostatic latent image to develop it~ an image having a high image density9 a high resolving power and a superior reproducibility of halftone and being free from :
ghost image formation and background fogging can be obtained in a developing zone by moving the surface of the developer-holding member and the surface of the electrostatic latent image~bearing member on contact wi-th each other in the same direction at such speeds that a speed difference of about 20 m/minute ~ IVl - V2l~0 m/minute is provided between the moving speed Vl of the surface of the developer--holding member and the moving speed ~2 of the surface of the ~lectro-static latent image--bearing memberO
~he speed difference differs somewhat according9 ~ 11 -. .. . . . . . . .
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~L~'~093 for example, to the potenti.al of the electrostatic latent image to be developed or the characteristics of the de--veloperO It is generally about 20 m~minute>¦Vl .- V2l>
about loO m/minute, preferably about 20 m/minute ~
¦Vl - V2¦~ about 3O5 m,~minuteO Especially, the Vl -- V2 is preferably a positive valueO
~his new finding is described in more detail with reference to Figure 20 Electrostatic latent image~bearing member 2 having an electrostatic latent image formed on its surface, which is, for example, a rotary drum having a photoconductive layer of selenium or cadmium sulfide is rotated in the direction shown by arrow B (clockwise di-rection in ~igure 2)o In developing section 4, the electro-static latent image formed on the surface is developed by a developing device generally shown at 6~ The electrostatic :: . la-tent image to be developed is formed on the surface of the latent lmage~bearing member~2 upstream of develop--ing station 4 by any method known to those skilled in:the artO
Developing device 6~in~cludes developer-holding member 8 to be rotated, magnet lO disposed within the member 8 and developer supplier~l4 for~supplylng developer 12 to~
thc surface of developer-helding member ~ 80 ~eveloper-;~ holding member 8 may be any desired material which can magnetically hold -the developer supplied from supplier 14 to the surface of the developer~holding member by the action of magnet 10 and can be contacted wi-th the surface of electrosta-tic latent image~bearing member 2 through the developer in developing station 4O ~or example 9 it may be - 12 ^
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~ ~3a~3 made of an endless belt. A suitable developer-holding member is made of a hollow cylindrical sleeve and can be rotated in the direction o arrow C in Figure 2 (in the counterclockwise direction in Figure 2). Furthermore, when the developer used is a mono-component developer composed of a conductive or semiconductive magnetic fine powder (the developer will be described in detail herein- .. .
below), a developer-holding member composed of a main body of a nonmagnetic metalli.c material and an insulating coating ormed on the surface of the main body is used suitably. Preferred insulating coatings are, for example, . organic insulating coatings such as polystyrene or poly- :
ethylene terephthalate, inorganic insulating coatings such as aluminum oxide, or composites.of these, which ~ .
have at resistance of at least 103 ohms/cm2, especially at least 105 ohms/cm2.
` Magnet 10 to be disposed within developer-. holding member 8 may be o any type which has the action of magnetically holding the developer onto~the surface of developer-holding member 8. When developer-holding -.
member 8 is a hollow cylindrlcal sleeve as shoun in th~e ~`. drawings, the magnet is pre~erably a statlonary roll-like - permanent magnet having a plurality (for example, 8~ of .
~ magnetic poles which.are located on its periphery and alternately have opposite polarities. Preferably, as - shown in Figure 2, such a stationary roll-like permanent -.
magnet is generally fixed within the developer-holding member such that one of the magnetic poles is positioned - 1.3 -- , :
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Z~3 upstream in the rotating direction of the developer--hold-ing member by angle ~ with respect to position P at which the surface of electrostatic latent image-bearing member 2 approaches the surface of developer-holding member 8 most closelyO If, however~ developer--holding member 8 is rotated at ~ fairly high speed~ it is sometimes preferred to position one of the magnetic poles of the permanent magnet at position P at which the surf2ce of developer-hold-ing member 8 approaches -the surface of the electrostatic latent image-bearing member most closelyO When developer-holding member 8 is rotqted a-t a fairly high speed9 the developing statiOn (-the contact zone between -the developer and the surface of image-bearing member 2) must be increased by bringing the surface of image-bearing member 2 closer to the surface of developer--holding member 8 to maintain the developing time (the time during which -the surface of the electrostatic latent image--bearing member is in contact with the developer)0 If one of th^ magnetic poles is positioned at a point somewhat farther upstream of position P in this case, the surface of electrostatic latent image~bearing member 2 contacts the developer even at an intermediate point between magnetic poles, and development occurs also at this pointO
q'he developing device 6 fur-ther includes a brush length adjusting mesns such as a doctor blade for control-ling the thickness o~ the developer layer which has been supplied to the surface of developer-holding member 8 from developer suppIier 14 and held there magneticall.yO ~he brush length adjusting means can be made up of, for .. . .
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example~ member 16 which is adjustably secured to side wall 14a of suppliel 14 that is positioned downstream in the rotating directlon of developer holding member 80 Member 16, as is clearly shown in Figure 3~ tapers toward its free end which is positioned near the surface of developer--hold-ing member ~ at a point at which one of the magneti,c poles of magnet ],0 is situated in its vicini-tyO Preferably9 the thickness of the free end is more than 0 mm and up to 005 mmO ~he angle ~ defined by both side surfaces of -the free end is not more than 15 9 preferably not more than 10o ~ referably~ member 16 constituting the brush length adju.sting- means is disposed near the surface of developer-holding member 8 somewhat upstream of one of the magnetic poles of magnet 10 in -the moviDg direction of the surface of developer holding member 80 According to this construction, because of the form of the line of magnetic force generated by magnet 10~ the developer within developer supplier 14 is not urged against member 16 and does not solidify there~ Accordingly, a layer of the de-veloper having a~good surface condltion is formed on the surface of developer-holding member~8~ and -the toner image developed increases in ~ualityO It is also preferred that the tip of side wall 14b which forms one edge of the de-veloper outlet of developer supplier 14 and is positionedupstream in the rotating direction of developer-holding member 8 should be disposed somewhat upstream of one of the magnetic poles of magnet 10 in the moving direction of the surface of developer holding member 80 According . . ............ . . . .

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Og3 to this embodiment9 the developer is not carried to the outside tip portion of side wall. lL~b of the developer supplier because of the form of the line of magnetic force genera-ted by magnet lOo Distance dl between the free end of member 16 and the surface of developer-holding member 89 as will be described hereinbelow~ is c].osely related to distance d2 between the surface of developer-holding member 8 and electro~
static latent image-bearing member 2 at position P at which these surfaces approach each other most closelyO Generally, distance dl is 0015 mm~ dl_ 005 mm9 especially 002 mm~ d _ 0045 mmO If distance dl is -too small, a sufficient amount of the developer cannot be supplied to devcloping station 40 Conversely9 if distance dl is too large9 the layer of the developer held on the surface of developer holding member 8 becomes thick9 and the developer which is situated at the outermost position is held by a weak holding forceO Consequently9 the scattering of the developer occurs at developing station 49 and the image developed is foggedO
On the other hand9 distance d2 between the surface of de~
veloper-holding member 8 and the surface of electrostatic latent image-bearing member 2 at position P at ~hich they approach each other most closely is closely related wlth the distance dl described aboveO Generally9 the distance d2 is 006 mm~ d2~ dl~ preferably 0055 mm' d2~- dlo According to the information which the present inventors have obtained through research and experimental work9 the distances dl and d2 are preferably within the area defined by a line connecting the four points .

(0015~ 0025)~ (0059 006)9 (Oo259 006) and (0015, 005) in a graphic representation of Figure 4 in which d, (mm) ls on the axis of abscissas and d2 (mm) is on the axis of ordinates, and especially preferably within the area defined by a line connecting the four points (0~2, 0 3), (0045~ 0055)9 (0~25~ 0055) and (Oo29 005)o Distance d3 from the forward end of side wall 14b located upstream in the rotating direction of the de-veloper-holding member~ which defines one edge of -the developer outlet of developer supplier 14, to the surface of developer--holding member 8 is generally 5 mm->d3 >1 mm, preferably 3 mm2 d3> 2 mmO
: Developer 12 is suitably a known mono-component developer composed of a single conductive or semiconductive fine powder with a par-ticle diameter of 5 to 30 microns, preferably 8 to 15 microns which is obtained by coating a fine powder of iron~ cobalt or nickel, or an oxide of such a metal, or an alloy of such a metal, or a mixture of these with a resin such as an epoxy~ styrene or olefin resin, or further adding a suitc~ble coloring agent such as carbon blackO ~ : ~
In developing device 6 described above, the surface of the developer-holding member within developing station l~ is contacted with the surface of electrostatic laten-t image-bearing member 2 through developer 12 retained on its surfaceO It is important that the two surfaces should be contacted with eflch other through developer 12 in the manner to be described belowO
Electrostatic la-tent image--bearing me~ber 2 is : . . .
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rotated at e fi.xed speed in the direction of arrow B
(that i5~ in the clockwise direction in Figure 2)9 and developer-holding member 8 is rota-ted at a fixed speed in the direction of arrow C (that is, in the counterclock-wise direction in Figure 2)o Eence, the surface of image-bearing member 2 and the surface of the developer-holding member are moved in the same direction in developing statiOn 4- where the surface of developer-holding member 8 is con~
tacted through the developer held on it with the surface of image-bearing member 20 These members are moved at such speeds that the moving speed Vl of the surface of developer-holding member 8 differs from the moving speed V2 of the surface of image~bearing member 2 as follows:
about 20 m~minute~lVl - V2 1> m/minuteO
As described in de-tail with reference to Figures l-a to l-c9 when a mono-component developer composed of a single type of magnetic fine powder is used in the known rolling contact method which involves moving the surface of developer-holding member 8 and the surface of image-bear-ing member 2 at substantially the same speeds ~Vl ~ ~2 = )' a ghost image is formed and the background is fogged, because the developer adheres -to the surface of image-bearing member 2 too faithfully ~ccording to the potential pattern of the surfaceO If 9 however, the surface of developer~-holding member 8 and the surface of image~be~r-ing member 2 are moved in the same direction at different speeds as described above9 the developer which adheres thinly to the nonimage erea with a weak adhering force and is likely to cause ghost image formation and background ~- 18 ..

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fogging is scraped off by the mechanical brushing action of the develope~r held magnetically on the surface of developer--holding member 80 r~he scraping of the developer is done without substantially reducing the density and resolving power of the image area and the reproducibility of half-tone~ and the image obtained is free from ghost image formation and background foggingO If the speed dif-ference (Vl - V2) is larger ~than about 20 m/minute, the mechanical brushing action of the developer magnetically held to the surface of developer-hol.ding member becomes excessive9 and the resulting image has a low density, a poor resolving power9 and a poor reproducibili-ty of half-toneO Or becau$e the developer spplied to the developing station by the rotation of developer~holding member is in-sufficient, the density of the resulting image decreasesO
Preferably~ the speed diff~erence (Vl - V2) should be a positive valueO If the speed difference (Vl - V2) ~ ~ . is a negative value (in other words, lf the moving speed : Vl of the surface of developer-holding member 8 is smaller than the moving speed V2 of the surface of image-bearing meberr 2), the amount of the developer supplied to developing station 4 by -the rotation of developer-holding member 8 tends to be insufficientO Specifically9 therefore, it is preferred to render the~moving speed Vl of the surface of developer-h~lding member 8 somewhat larger than the moving speed V2 of the surface of the image-bearing member 20 .The optimum speed difference Vl - V2 differs somewhat according to the magnitude of the potenti~l on the electro~
static latent image to be developed, the characteristics : - 19 ,, , ~ , . ..

Z~11)93 of the developer (the sensitivity of the developer to the potential)~ the magnetic holding power of the magnet for the developer~ the moving speed (iOeO, the developing speed) of the surface of image-bearing member 2, etcO In the development of an electrostatic latent image ln an ordinary electrostatic copying processg the speed difference is about 20 m~minute to about loO m~minute~ preferably about 20 m/minute to about 3O5 m,/minu-teO
Exam~le In an apparatus of the type shown in Figure 2, a rotary drum made by vacuum-dep0siting selenium on the surface of a cylindrical aluminum support with a dia~meter of 120 mm was used as an electrostatic latent image--bear-ing memberO ~he surface of the rotary drum was uniformly charged by positive corona dischargeO An original image was : projected on the drum surface charged to a fixed positive potential (Vs) -to form an electrosta-tic latent imageO
A toner composed of a mono-component magnetic powder : was supplied from a de-~eloper supplier to the surface of ~ de-veloper~holding member made of a non-magnetic cy1indrical : sleeve having a magnet disposed ins1de~ thereby to form a layer of the toner on the surface of the sleeveO The strength of the magnetic force on the surface of the sleeve was about l~000 GaussO ~he particle diameter of the toner Z5 was adjusted to 5 to 30 1l to obtain a good quality image and prevent the scattering of the toner particles at the time of transferO ~he cylindrical sleeve Was rotated at a suitable peripheral speed to convey the toner magnetically attracted to the surface of the sleeve to ? developing - 20 ~

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positionO
Thus, the toner was ?~pplied to the electrostatic latent image to form a toner imageO The toner image formed by developmerlt wcqs then transferred to a receptor sheet and fixed on it under pressureO
The residual charge on the rotary drum after the transferring operation w~s removed by the irradiation of light, and the residual toner was removed by the developing device itself or by a suitable cleaning device equivalent to the developing deviceO
In the formation of the electrostatic latent image, the surface of the rotary drum was charged so that its surface potenti~l Vs would become about 700 V at the tlme of developmentO Then, ?a ligh-t image and a dark image of the reflecting light from an original which had been ir-radiated with light (adjusted to about 450 W) from a halogen lamp with a rating of 700 W (the length of the light emit-~:~ tlng portion was about 280 mm) were projec-ted on the surface of the rotary drum using two reflecting mirrors and an in~
mirror lensO The reflecting~ratio of the reflecting mirrors ; was more than about 95%, and the lens had an F value~of 5O3 and a focal length of 2Z5 mmO
he cylindrical sleeve used in the development ~; was a hollow cylindrical body of aluminum with a diameter of 32O4 mm, and an aluminum oxide coating obtained by anodi-zation at a low tempera-ture was formed on the surface of the sleeveO The hollow cylindrical body was grounded during useO The shape of -the developer supplier9 the brush length adjusting member and other parts are as ,:.

1~0~93 illustrated in Figure 20 (A) Distance (dl) be-tween the surfi~ce of the cylindric~l sleeve and the end of the 'orush length adjusting member, and distance (d2) between these surfaces at R point where they come closes-t to each othe~:-~xperiment was performed under the af~rescid experi.mental conditions while varying dl and d2, and the results shown in ~`able 1 were obtainedO

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1-- ' l O O O O- O O O O O O O O Oi 1~ .' /~ _ _ _ _ _ _ _ _ '''.' ~r lZ~ 3 ~ he results obtained are discussed briefly below~
When d2 is shorter than dl + 0O05 mm, the thick-ness of the -toner layer on the surface of the sleeve is lc~rger than d2u Accordingly, the toner is compressed and solidlfied in the developing zone9 ~nd the development of the electrostatic latent image becomes poorO When dl is shorter than Ool mm~ the toner density of the toner layer on the sleeve surface is low9 and the density of the toner image does not increaseO ~lrthermore~ when dl is less than 0~1 mm, mechanical accuracies~ for example in the eccentricity of the cylindrlcal sleeve or the rotary drum, are rigorously ; requiredO When within the range of dl> Ool mm~ d2 is more than dl + 0O45 mm, d2 is far larger than~dl~ and the toner layer does not make sufficient cont~.ct with the photosensi-tive surface of the drum, and no useful toner image can be obtainedO When the distance d2 between the surface of the rotary drum and the surface of the cylindrlcal sleeve exceeds 0O7 mm, good results oan~ot be obtained~ ~When d2 is larger than 0O7 mm, the toner layer to be held magne-tically onto the surface of the~sleeve~must necessarlly be increased in thicknessO When~the thickness~of the toner layer increases, the magnetlc force~ exerted on the toner particles which will contact the rotary~drum is weakenedO
Accordingly, the electostatic force between the electro : static latent image and the toner increases to increase foggingO At the same tlme, the rotation of the sleeve causes the scattering of the toner particles to soil the copying machineO When the dist~.nce dl is maintained constant, the density of the toner layer is determined according to the flowability and particle diameter of the toi~er9 -the interpole distance of the magnetic roll, the magnetic flux intensity of the ma.gnet~ etcO Hence, the distance dl should be determined 2~ccording to these con--ditionsO
~B) Rela-tion between moving speed V of the surface of the cylindrical sleeve and --moving speed V2 of the surface of the rotary drum:-(a) In consideration of the results obtained in (A), the above experiment was~performed while maintaining ~ 10 dl = 0025 mm and d2 = 004 mm and the peripheral speed V2 : of the rotary drum at 11 m/minO ~he cylindrical sleeve was moved at varying peripheral speeds V2 in the same di-rection as the rotating direction of the rotary drumO ~he results obtained are shown in ~able 2D

~: :

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, _ ~ ~ ~ ~ ~1 ._ . __ _ . ... ~ ~ ~ O ~ O
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When the peripheral speed V~ of the rotal~ drum i5 11 m/minO ~ a toner image of good quality is obtained within the area of 1908 > V] - V2~ 2041, or -2005> Vl ~ V2 > -9060 When Vl i9 1oW9 non-uniformitv in image tends -to occur owing to the non uni.formity of the speedO ~ence, a special care mus-t be taken -to minimize the non-uniformity of the speedO When Vl is 0, the toner is not supplied to the developing zone~ e~nd therefore, an image CannOt be obtainedO When the peripherel speed Vl of the cylindrical sleeve is equal to the peripheral speed V2 of the rotary drum (Vl ~ V2 = O), the rotary drum and the cylindrical sleeve are brought into rolling contact with each other through the toner layer9 ar.d toner adhesion occurs very .
faithfully to the electrostatic laten-t imageO However, the residual poten-tiel on the ro-tary drum coated with photo-sensitive selenium for ex~mple is high9 -too faithful a de-velopment is not desirableO The resistivity of the toner shown in T~ble 2 is a value obtained when a DC voltage of 50 V is applied to the toner layer ha~ing a thickness of 105 mmO The density of the lmage decreases with increasing resistivity of the tonerO Howeverg the image becomes hard in tone 9 and increases in sharpnessO
(b) The toner i.mage ob-tained by forming an electrosta.tic latent image varles according to the maximum potential of the surface of the rotary drum (iOeO, the maximum potential Vs of the elec-trost&tic latent image formed) and the resistance (R) of the tonerO To make sure of this, the relation of the toner image to the Vs and R values at Vl - V2 = 305 m/minO was examinedO The results are shown in Table 30 2~ 3 o ` L I ` ~1 ''_ ~ I __ __ .~ ~ ~1 ~_ __ _ o _ L ~ ~ ~ :~ ~
o r--L ' ~ I~L- ~

¦ r~ I ! ~ X ~ PC PC I X ¦ Pq ¦
o~ ~ 1 ~ 3 O r I ~ T~ 3 ~i ~ ~ I <1 _ . _ . ~ _ _ _ _ A L~ o ~ ~ L~
o ~ ~I~ J`~ ~)I ~` ~

P¦ O~ ~- L~ ~ = ~ ~ ~
o~ ~ c~ ,~ ~ ~q . . _ I -I
~o O 0. ~ ~ ~ ~, ~ .
_ ~o O ~ ~ q P~
.. ~ ~ ............ i. .. ~... I -o ¦ G ~ G ~

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;~ I a.~i~ / I I i 1 I I
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a) ~ I o IO I~)0 ICiO ¦ r~O ¦ r~ I (U ¦ r~ I
r~ Ir-l Ir~ Ir~ I r~l Ir~l I r-l I r~ r~ I
rl q~l ~ ~J II I I I I I I
i / lVOg~

When the surface potential Vs reaches 800 V, a ghost image begins to appear~ When it exceeds 1000 V, the ghost image increases very much, and the resulting image is uselessO When the resistivity of the toner exceeds 1014 ohms-cm, a sufficient image density cannot be obtained unless the surface potential is increased extremelyO Toner particles having a low resistivity adhere to the electrosta-tic latent image in an increasing amount, and therefore, the fog density increasesO For this reason, a good image cannot be obtained unless the surface potential is reducedO When the surface potential is less than 200 V, -the density of the image decreases extremely (the reflectlve image density is 1ess than 0~5), and the image obtained is not feasibleO Even when the surface potential is less than 200 V and the resistivity of the toner is less than 106 ohms-cm, the density of the image can be increased by weakening the magnetic force ~ of the developer-holding memberO However, sLnce the surfaCe : potential of a bright area of the image (the residual poten-: 20 tial) is almost constant, the amount of the toner adhering ~: to the residuaI potential increases, and the resulting image has an extremely high fog densityO
Electrostatic copying process which involves developing an electrostatic latent image formed : 25 on a photosensitive member, and transferring : the developed image -to a receptor sheet (the toner ima~e-transferrin~ step~
As described hereinabove, various forms of electro-static copying process exist for producing a copied image

3 corresponding to the image of an originalO In recent years, there has been an increasing demand for "plain paper copying . .

..

(PPC)" by which a copied image is formed on a sheet of plain paper (including papers somewhat processed but being substantially equivalent to plain paper)O
'~he electrostatic copying process for producing a oopied image on plain paper generally includes a step of forming an electrostatic latent image corresponding to an original image on a photosensitive member, a develop-ing step for applying a fine powder developer (toner) to the resulting electrostatic latent image to render it visible, a step of transferring -the toner image on the photosensitive mamber after the transferring, and a cleaning step for removing the toner remaining on the photosensitive member after the transferringO
Referring to Figure 5, the electrostatic copying process is briefly described belowO ~he photosensitive member (io e~, the electrostatic latent image-bearing member) 2 which is in the form of a photosrnsitive drum to be driven in the direction of arrow B first undergoes the action of corona discharge device 20, and a static charge is applied to the surface of photosensitive member 2 (the charging step)0 ~hen, the image of an original (not shown) is projected onto the surface of the photo-sensitive member 2 by an op-tical system 22 in an original image exposing zone located downstream of the corona dis-charge device in the rotating direction of photosensitivemember 2 (the step of exposing an original image)O Con-: sequently, an electrostatic latent image corresponding to the original image is formed on the surface of photosensi-tive member 2 (the electrostatic latent image-forming step)O

f~ 3 ~hen, by a developing device 6 desirably of the type shown irl ~igure 2, a fine powdery developer (toner) is applied to the electrostatic latent image on the surface of photosen~itive member 2 to develop the latent image into a toner image (the developing step)0 ~hen, the toner image on photosensitive member 2 is transferred in trans-ferring zone 24 to a receptor sheet fed from a receptor sheet supplying section composed, for example, of paper supply cartridge 260 ~he receptor sheet having the toner image transferred to its surface is sent to fixing device 28 constructed, for example, of a pair of press rollers, and the -toner image is fixed to the receptor sheet under pressure, after which the shee-t is discharged onto receiv-ing tray 30 (the fixing step)~ In the meantime, the photosensitive member~ after the -toner image formed on it has been transferred to the receptor sheet, is irra-diated with electrostatic e]iminating lamp 32, whereby the residual charge on the photosensitive m~mber is re-moved (the charge eliminating step30 ~he toner remaining on the photosensitive member is removed (the cleaning step)0 ~oner ima~e transferrin~ step ~ he toner image transferring step in the electro-static copying process summarized above is conveniently carried out generally by bringing the surface of photo-sensitive member 2 lnto close contact with the surfaceof the receptor sheet in transferring zone 24, and applying a discharge current to the receptor sheet from its back using corona discharge device 36 for transferO
The toner image transfer method described, , ' ' ' ` ' ' ' i ' ~L~L'~o93 however, has the defect that some distortion occurs in the toner image transferred onto the receptor sheetO
~he present inventors extensively s-tudied the distortion of the toner image, and obtained the following informationO
In the conventional method for toner image transfer, the receptor sheet to be fed into the transfer zone first passes between shield side plates of corona discharge device 36, and is then brought into close contact with the surface of photosensi-tive member 2~ Accordingly, before the surface of photosensitive member 2 comes into close contact with the surface of the receptor sheet, both surfaces are influenced by the discharge current of dis-charge device 360 As a result, the toner on the surface : of photosensitive member 2 or on the s~rface of the receptor sheet undergoes vibration between the two surfaces and is thus scatteredO Scattering of the toner, in turn, causes the distortion of the toner image txansferred to the receptor sheetO
On the basis of this information, the present inventors have found that the distort1on of the toner image on the recep-tor sheet can be effectively prevented by bringing the surface of photosensi-tive~member 2 in-to close contact with the surface of the receptor sheet as soon as, or before, the recep-tor sheet passes between the shield side pla-tes of corona discharge device 36 (that is to say, before the receptor sheet enters a:zone where it is influenced by the discharge currentj, and thereby physically preventing the vibration and ~cattering of the toner particlesO

- ~2 -, ~ , . .
,. ~. ., ~.

i~Z0(~93 : r~he close contact of the surface of photosensi-tive member 2 with the surface of the receptor sheet before the passing of the receptor sheet between the shield side plates of corona discharge device 36 can be achieved, for example., by positioning the ends of the shield side plates (especially the one which is more up-stream in the moving direction of the receptor sheet) of corona discharge device 35 in proximity to -the ~ surface of photosensitive member 2, and properly disposing, with respect to corona discharge device 36, that part of the receptor sheet conveying path which is situated up-stream of corona discharge device 36 in the moving direc-tion of the receptor sheet (the path is formed by receptor : sheet guide plate 38, etcO although this is not shown in detail in the drawings), as shown in ~igure 50 : ixin~
~ he receptor sheet closel~ containing the surface of photosensi.tive member 2 in the transfer~step is separated from the surface of photosensitive member 2 by such a means as peellng nall 40 at~a~point downstream : of transfer station 240~ It is~then conveyed to receiving tray 30 through fixing device 280 ~ ~ ~
In the step of conveying~the receptor sheet from transfer station 24 to receivlng tray 30, the receptor 25 ~ sheet collects statlc ch æge at the time of transferring or fixing the toner image by fixing device 280 r~he:electro ~ static charge may cause the receptor~sheet to turn upward : from -the surface of guide plate ~2 ln the transfer path from transfer statlon 24 to fixing device 28, and thus - 33 ~

- - . . , . -t3 paper jamming occursO Or the electrostatic charge causes the receptor sheet to turn upward at the time of dis-charge into receiving tray 30~ and the receptor sheet cannot be properly discharged onto receiving tray 300 The present inventors have found that if electro-s-tatic eliminator 44 is provided above receptor sheet guide plate 42 in the receptor sheet conveying path between transfer station 2~ and fixing device 28, the action of eliminator 44 urges the receptor sheet against the surface of guide pla-te 420 Thusg -the receptor sheet is conveyed in good condition without paper jamming and other troublesO
If electrostatic eliminator 46 is provided above the end of the receptor sheet conveying path tioeO, above the inside end o~ receiving tray 30), the action of eliminator 46 urges the receptor sheet downward~ and thus prevents it from turning upward at the time of discharging onto receiving tray 300 :Electrostatic ellminators 44 and 46 may con-veniently be "sparkless electrostatic eliminators" which are obtained by processing an electrically conduc-tive cloth or resin plate9 a cloth having fine electrically conductive fibers or fine metal ~wires interwcven or a film having a conductive fine powder dispersed in the resin into a saw teeth form so as to:permlt a corona discharge between the sharp edges of the saw teeth and a charged bodyO
~ Cleanin~ ste~
: After the transferring of the toner image formed on the surface of photosensitive member 2 to the surface of the receptor shee-t in transfer station 24~ the toner - ~ , . ,. ~ . ~
; . , , ~ ............... :. ;
, , . . ~ ."

remai.ning on the surface of photosensitive member 2 can be removed by various methods, for example, by lightly rubbi.ng the surface of photosensitive drum 2 with a rotary Fur brushO Pre:Eerably~ cleaning can be performed by contacting a hollow cylindrical or endless belt-like, developer-holding member having a toner magnetically held to its surface by the action of a stationary permanent magnet disposed in its inside~ with the surface of photo-sensitive member 2 through the developer layer on the developer-holding member while providing the largest possible difference in speed between them (therefore~
it is preferred to move the surface of the developer-holding member in a direction opposite to the moving direction of the surface of photosensitive member 2) o Referring to Figure 7~ cleaning device 34 which performs the cleaning method described above includes developer-holding member 50 preferably of a hollow cylindrical form, and stationary permanent magnet 52 disposed within ito Preferably9 developer-holding member 50 and magnet 52~are e~uivalen-t to developer-holding member 8 and magnet 10 used ln developlng device 6 des-cribed hereinabove with reference to Figure 20 ~he developer-holding member 50 magnetically holding toner 12 (same as the toner used for development) on its surface by the action of magnet 52 is rotated in the direction of arrow D (in the clockwise direction in Figure 7) so that its surface moves in a direction opposite to the moving direction of the surface of photosensitive member 20 ~hus, -the surface of developer-holding member 50 is continuously . . , : , ~ , . . .
, ,~
,. , ': , . ' , ': . , r^

contacted with the surface of photosensitive member 2 through developer layer 120 Brush ].ength-adjusting member 56 secured to frame member 54 is provided at a position downstream by a fixed distance from position Q
(at which the surface of developer-holding member 50 is closest to the surface of photosensitive member 2) in the rotating direction of member 500 ~he end of brush length-adjusting member 56 is close to the surface of developer-holding member 50, and serves to remove -the ; ~ excess of the developer from developer-holding member 50 ~: and adjust the length of the developer brush on developer-holding member 50 to tne desired valueO ~rame member 54 has receptacle 5~ removably secured to ito Receptacle 58 ; is positioned benea-tk brush length-adjusting member 56 and is adapted to receive the developer which has been removed from the surface of developer-holding member 50 by the action of brush length-adjusting member 56 and fallen downwardO
.. ~ , . -In cleaning device 34, the surface of developer-holding member 50 is moved in a direction opposite to the moving direction of the surface of pho-tosensitive member 20 Hence, developer layer 12 magnetically keld on the surface of developer-holding member 50~slides:over -the surface of photosensitive member 2 at a falrly high relative speedO
~he mechanical brushing action of the developer ~thus causes the remainlng toner on the surface of photosensitive member 2 to be removed from i-t, and the toner is magnetically attracted to the surfaoe~of -the developer-holding memberO
~his action is more effective as the magnetic action of . , , magnet 52 is larger and the rotating speed of developer-holding member 50 is higher (io eO 9 the relative speed of the surface of member 50 and member 2 is larger)0 The developer layer on developer-holding member 50 which has become excessive as a result of the adhesion of the developer removed from the surface of photosensitive member 2 undergoes the action of brush leng-th-adjusting : : member 560 As a result, the excess of the developer (the amount of the developer which corresponds to the amount of the developer removed from the surface of photosensitive member 2) is removed from developer-holding member 509 and le-t fal.l into receptacle 580 In the cleaning method uslng cleaning device 34 described above, it is important to avoid the formation : 15 of a deposit of the developer in area 60 which is upstream :~ of position Q at which the:surface of photosensitive member :.
; 2 is closest to the surface of developer-holding member 50 : in the moving directlon of the surface of photosensitive member 20 ~he deposlt of the deve1opsr~is formsd by the developer which has been~carried to area 60 by developer-holding member 500 If the:~dsposlt of~the developer lS~ -formsd in area 60, the surface~of~ photosensltivs membsr 2 : which has been mechanically brushed at position Q then makes contact with the deposit of the developer not suf-~: : 25 ficiently held to the surface of developer-holding member 500 As a result, the~developsr would again adhere to the : surface of photosensitive member 20 lo avoid the formation of the deposit of the developer in area 609 it is importan-t to dispose magnet 52 ~ . ,. . .. ~ .; . :

~,~5)93 so that one of the po]es of magnet 52 which is closest to position ~ is positioned downstream of the rotating direction of the developer-holding member 50 by certain angle ~ which is preferably not more than 15 with respect to posi.tion QO
It is also very important -to properly adjust distance d~ between the surface of developer-holding member 50 and the surface of photosensitive member 2 at position Q where the two surfaces are the closest to each other, and distance d5 between the end of brush length-adjusting member 56 and the surface of developer-holding member 500 Distance d4 can be set wi.thin the range of 102 to 005 mm, and distance d5 within the range of 006 to 0025 mm, in such a manner that the deposit of the developer will not formO
Cleaning can be performed fairly well even if the rotating direction of developer-holding member 50 is the same as the moving direction of photosensitive member In this case, the relation between d4 and d5 is quite the same as that between d2 and dl described hereinaboveO

Decreasing of the amoun-t of the developer :
to ~

It is known -that in -the conventional electro-static copying appara-tus for performing the electrostatic copying process described herelnabove with reference to ~igure 5, the amount of the developer to be removed from the surface of photosensitive member 2 by cleaning device ~4 and received by receptacle 58 is fairly largeO ~he reason for this has been investigatedO It has been ," ! ' I ' , 3~h~093 consequently found -that the amount of toner particles which remAin on the surface of photosensitive member 2 after the transfer i.s relatively small and can be neglected if -the toner image transI'erring step i.s carried ou.t with a good transfer efficiency; and that the amount of toner particles which are carried to the cleaning device as adhering -to the surface of photosensitive member 2 is considerably lar~e~ and a considerdble portion of the developer particles removed from the surface of photosensi-tive member 2 lnto receptacle 58 by cleaning device 3is the la-t-ter-mentioned tonerO
In the conventional electrostatic copying appa-ratus, corona discharge device 20 for charging and the original illuminating lamp (no-t shown) of optical system 22 are adapted to be de-energized as soon as an electro-static latent image i5 formed on the surface of photo-sensitive member 2 by the charging step and image-exposing ~ stepO Hence, a part of the surface of photosensitive : member 2 which is positioned between the shield side plates of corona discharge device 20 upon the comple-tion of the electrostatic latent image-forming step is already charged~
and~ without being exposed to the l~ight from the lamp of optica]. system 22, proceeds to a position where it under-goes the action of developing device 6 by the rotation f photosensitive member 20 Hence~ a fairly large amount of the developer adheres to -that part of the surface of photosensitive member 2 which has been described above (the developer adheres to cover the entire surface black)O
~he above-mentioned part of the surface of photosensitive ~ `

member 2 does not form an image corresponding to an original imageO Usually9 without being contacted closely with the receptor sheet at transfer station 24, this part advances pas-t transferring stcltion 24, the position where it urldergoes the action of electrostatic eliminating lamp 32 to a position where it undergoes -the action of cleaning device 34O Accordingly~ a considerably large amount of the developer adhering to the above-mentioned part of the surface of photosensitive member 2 by the action of developer device 6 is carried directly -to a position where it undergoes the ac-tion of cleaning device 340 ~his developer is removed from the surface o~ photo-sensitive member 2 by the action of cleaning device 34, and consti-tutes a major proportion of -the developer received in receptacle 5~O -~he conventionaL electrostatic copying apparatus, therefore, has the disadvantage that a considerable amount ::
of the developer unwanted by developing devlce 6 is wasted, and the irradiating li.ght from electrostatio eliminating lamp 32 is shielded by the developer adhering the surface of photosensitive member 2 in the state of solid black and -the eliminating effect by electrosta-tic eliminating lamp 32 is insufficientO
~his disadvantage can be overcome to a consider-able extent by de-energizing only the corona discharge device 20 upon the completion of the electrostatic latent image-forming s-tep, and de-energizing the original-projecting lamp of optical system 22 with a predetermined time lag (substantially equal to, or longer than5 the time required until that part of pho-tosensitive member 2, which is situated between the shield side plates of discharge device 20 when corona discharge device 20 is de-energized, passes the original image proaecting zone by -the rota-tion of photosensitive member 2)o By so doing, that part of photosensitive member 2~ which has been charged when corona discharge device 20 is de-energized, i receives light from the original-illuminating lamp which is reflected by the white back surface of an original press member (not shown), the original, etcO in the original image projecting zone~ and thereby a considerable amount of the electrostatic charge applied to the above-mentioned ~ part of photosensitive member 2 is removedO
; As stated above, the light from the original-` 15 illuminating lamp is projected on the surface of photo-`~............... sensitive member 2 after it has been reflec-ted by the back surface of the original press member or by the originalO
Especially when the l~ight is~reflected by an original ; including an image area, the static charge applied to the . 20 above-mentioned part of photosensi-tive member 2 cannot be completely elim3natedO ~o elimlnate the electxostatic . charge exactly and completely, an additional static eliminating lamp (now shown) capable of lighting the . : surface of photosensitive rnember 2 directly or through a reflecting mirror is provided between corona discharge device 20 and developing device 6, and for a time period . which correspondsto the above-mentioned time lag, -this : additional eliminating lamp is energized upon the com-- pletion of the electrostatic latent image-forming step :, :.
.

(that is, when corona discharge device 20 and original-illuminating lamp of optical system 22 have been de-energized)0 ~he above~mentioned problem can therefore be completely solved by this contrivanceO If the toner image transferring step is carried out with a good trans-ferring efficiency (for e~ample9 at least ~5%, especially at least 90%) in the apparatus of this construction, -the amount of the developer which remains on the surface of photosensitive member 2 after transfer of the toner image is very small, and therefore, cleaning device 34 can be omittedO
~lec-trostatlc _u_~y~ A~e~r~tus ~ he following descrip-tion concerns a preferred embodiment of the elec-trostatic copying apparatus in accordance with this invention for carrying out the electrostatic copying process described above with re-ference to ~igure 5 which comprises applying an electro-static charge to the surface of photosensitive member 2 having a photoconductive layer by corona discharge device 20 (the charging step), -then projecting the image of an original on the surface of photosensitive member 2 by an optical system (the original image exposing step), thus forming an electrostatic latent~image corresponding to the : original image on the surface of photosensitive member 2, then applying a fine powdery developer (toner3 to the electrostatic laten-t image on the surface of photo-sensitive member 2 by developing device 6 to develop the latent image into a toner image (-the electrostatic latent image developing step), transferring the resulting toner : : , , ,, , ~,. . .
.
, . , , ~

~f~:~09~3 image to the surface of a receptor sheet (the toner image transferring step) 9 and fixing the toner image on the receptor sheet (the fixing step)O
General construction ~he general construction of the electrostatic copying apparatus is described with reference to Figures 8 and 90 ~he electrostatic copying apparatus has a sub-;~ stantially rectangular parallelpipedal housing shown generally at lOOo On the top surf'ace of housing 100 are : provided transparent plate 102 on which to place an original to be copied, flexible1 originaI-holding plate 104 for covering the original placed on transparent plate 102, and control panel 106 having control swi.tches and other components to be describedO
Rotary drum 108 having photosensitive member 2 mounted on its surface is disposed at the center of the lower half portion of housing;100~ Around drum 108 to be rotated in the direction of arrow B are arranged along the moving direction of the surface~ of~ rotary drum 108 a corona discharge device 20 for charglng, developing device ~ ~ 6, corona discharge device ~6 for transf`er, electrostatic : ~ eliminating lamp 32, and cleaning:device 34 in this orderO
Optical system 22 for projectlng the lmage of:an original placed on transparent plate 102 onto the surface of rotary ~:; drum 108 in an exposing station between corona discharge : device 20 for charging and developing device 6 is disposed above rotary drum 108 and within the upper half portion of housing lOOo Below the rotary drum and within the lower

- 4~ --. . .

~Z~093 part of housing 100 is provided conveyor system 112 for conveying a receptor sheet from paper-supplying cassette llOa or llOb mounted on one side portion of housing 100 (on the right-hand side in Figures 8 and 9) -to receiving tray 30 mounted on the other side portion (on the left-hand side in Figures 8 and ~) of housing 100 through a transfer station having corona discharge device 36 dis-posed in i-to Fixing device 28 composed of a pair of cooperating press rollers 114a and 114b is provided in a space in receptor sheet conveying system 112 which is between the transfer station and receiving tray 300 ~'he constituent elements of the apparatus are described in more detail belowO
: _ and a coolin~ s~stem ~ 15 Within housing 100 are disposed front vertical :~ base plate 101 extending from its one side to the other ` side and rear vertical base plate 10~ (see Figure 11)~
Between two base plates 101 and 103 is fixed partitioning plate 116 which extends from one slde of housing 100 to the other and partitions the space between two base plates 101 ~: and 103 into an upper portion including optical system : 22 and a lower portion including rotary drum 108, the various devices provided around rotary drum 108 and receptor sheet conveyor sys-tem 1120 As will be described hereinbelow, partitioning plate 116 has opening 118 through which to pass the light to be projected on the surface of rotary drum 108 by the optical sys-tem 2~o At a position on partitioning plate 116 which is apart from opening 118 to the left in Figure 9 by a fixed distance, the lower , , . ~ , -~Z~093 end of vertical transparent plate 120 through which the above light can pass is connectedO Preferably~ vertical transparent plate 120 is formed in the same thickness and of the same material as transparent plate 102D If vertical transparent .plate 120 does not have the same refractive index as transpa.rent plate 102, the.image : projected on the surface of rotary drum 108 would be out of focusO lhe upper end of vertical transparent plate 120 is connec-ted to a partitioning plate extending to the right side portion of housing 100O Partitionlng plate 122 has opening 124 at its right-hand side portion extend- -~ ing substantially horizontallyO Furthermore, partitioning :~: plate 126 for blocking the communication of opening 118 in partitioning plate 116 wi-th openlng 124 in par-titioning ~;~ 15 plate 122 is removabl-y secured between partitloning plates :: 116 and 122O
It will be appreciated therefore that the space between front vertical base~plate lOl and rear vertical : base plate 103 is partitioned into an upper half and a lower half by par-titioning plate 116,~ and;the upper half and lower half portions are eaoh sealed by the cooperation :
of partitioning plates 116~ 122 and 126 and vertical transparent plate 120 SO that they do not communicate with each o-ther~ ~
: 25 ~he upper half~por:tion of the space between front vertical base pla-te 101 and rear vertical base plate 103 includes optical system 229 and suction blower l30 which constitutes a cooling system for cooling original-illuminating lamp 12~ of optical system 22. As will be : . . ~ . ..... ~ ~

~:~ z~0~3 , described hereinbelow, this lamp 128 i.s adapted -to be reciprocated substantially horizontally within housing lOOo Suction blower 130 provided near the left end of the upper half portion sucks the air through suction opening 132 :Cormed on the left side wall of housing 100, as shown by arrowsO The air flow sucked by suction b].ower 130 is let out from opening 136 formed in partitioning plate 134, then proceeds toward the right of the upper half portion, passes through opening 124 of partitioning plate 122, further passes through discharge opening 138 formed on the right-hand side wall of housing 100, and is thus discharged f.rom housing lOOo This air flow effec-tively cools original-illuminating lamp 128~
Generally, original-illuminating lamp 128 of optical system 22 attains a considerably high temperature in opera-tionO It is necessary therefore to suck the air from outside the housing 100, direct the air flow to original-illuminating lamp 128 to cool it, and then discharge the air flow out of housing lOO o On the other hand, photo-sensitive member 2 having a photoconductiv~e layer mounted on the surface of ro-tary drum 108 is sensitive to heatO :
If, therefore, the air flow whlch has at-tained a high temperature as a result of cooling original-ill.uminating lamp 128 contacts -the surface of rotary drum 108, photo-sensitive member 2 is li~ely to be deterioratedO ~urther-more, if the air flow for cooling original-illuminating lamp 128 acts on developing device 6 and cleaning device 34 provided around rotary drum 108, the fine powdery developer will be sca-ttered by the action of the cooling . .
. ,. , : . : . : . . ~

air flowO It is likely therefore that the apparatus will be soiled or the resulting toner image will be distortedO
In the preferred embodiment oi the electrostatic copying apparatus of this ir..vention described hereinabove, the upper half portion of housing 100 in which optical system 22 and suction blower 130 are provi~.ed is non-communicatively partitioned by the cooperation of par-ti-tioning plates 116, 122 and 126 and vertical transparent plate 120 from the lower half portion of housing 100 in which rotary drum 108 and devloping device 6 and other components around rotary drum 108 are providedO Accordingly~ -the air .flow which is sucked by suction blower 130 through suction opening 132 and discharged from discharge opening 138 to cool original-illuminating lamp 128 does not flow into the lower half portionO Consequently7 there is no likelihood of the deterioration of photosensltive member 2 by the hot air flow, or of the soiling of the apparatus and the distortion of the -toner image by the.scattering of the toner particlesO
In the preferred embodiment of the electrostatic copying apparatus of this invention, partitioning plate 122 is provided which has a portion extending from the ~: upper edge of discharge opening 138 formed on the right-hand side wall of housing 100 substantially horizontally to the inside of housing 100 by a fixed distanceO Parti-tioning plate 122 has opening 124 for the air flowO
Accordingly, -the air flow for cooling is well discharged through opening 124 and discharge opening 138~ but the light ~rom illuminating lamp 128 is mostly shielded by the par-t of partitioning plate 122 and the right-hand wall of housing 100 which are at right angles to each otherO Hence, the light from lamp 1.28 does not leak from housing 100, and the:refore, is not likely to affect the eyes of -the opera-torO ~o prevent ligh-t leakage from lamp 128 completely9 a plurality of shielding plates (not shown) inclined at a fixed angle may be provided at intervals at opening 124 and/or discharge opening 1380 Partitioning plates 1169 122, etcO also have an effect of reinforcing housing 100 and increasing its rigidityO
In the embodiment shown in the drawings9 vertical transparent plate 120 is provided at a position spaced to the left from opening 118 of partitioning plate 116 by a fixed distanceO Alterna-tively, transparent plate 120 may be provided directly at opening 118 of partitioning plate 1160 In this case9 the upper half portion of houslng 100 including optical system 22 and suction blower 130 is non-communicatively separated from the lower half portion including rotary drum 108 and developing device 6 and other component parts around the drwn only by means of partitioning plate 116 and transparent plate 120 provided at opening 1180 If desired7 therefore, auxil.iary parti-: tioning plate 122 can be omittedO If9 however9 the pro-vision of auxiliary parti-tionlng plate 122 is omitted9 a considerable amount of the light from lamp 128 of optical system 22 lea~s from housing 100 through discharge opening 1380 ~urthermore9 it is li~ely that the light from out-side housing 100 will fall upon in-mirror lens 144 to " ., . -11~s)093 cause optical noises to optical system 220 Accordingly~
when auxiliary partitioning p:late 122 is to be omitted, lt is desirable to provide a plurali.ty of light shielding plates inclined at a fi.xed angle at i.~tervals in dis-charge opening 1380 Instead of providing transparent plate 120 at opening 118 of partitioning plate 116, one or a plularity of air jet nozzles may be provided near opening 118 so that the upper portion of housing 100 is non-communicatively separated from its lower por-tion a-t opening 118 by the action of an air flow which flows somewhat upwardly into opening 118 from -the tips of the air jet nozzles (by the so-called air curtain action)O ~he pressure of the air flow from the air nozzle needs to be e~ual to, or somewhat higher than, the pressure of the cooling air stream which would flow from -the upper portiontO the lower portion of housing 100 through opening 118 in the absence of such air flow from the air nozzlesO ~hen such an air nozzle is providéd and transparent plate 120 having the same refractive inde~ as transparent plate 102 on which to place an original is absen-t~in the light path extending from in-mirror lens lL~ of optical system 22 (optical system 22 will be described in de-tail hereinbelow) to the surface of rotary drum 108~ this light path must be adjusted to include the light path that would be increased by the refractive index of transparent plate 1020 If further desired, instead of providing an air curtain as descri.bed above, the flowing of the air stream from -the upper portion to the lower portion of the housing can be _ Llr9 _ .

LZ~g3 blocked by providing a suitable sucking means in the lower portion of housing 100 to maintain the air pressure in the lower portion somewhat higher than the air pressure of the upper portion o~ the housingO
~ s _ Now, referring to ~igures 9 to 11 9 the optical sys-tem is described in detailO
Optical system 22 includes original-illuminating lamp 128, first reflecting mirror 140, second reflecting mirror 142, in-mirror lens 144, and third reflecting mirror 1460 Illumina-ting lamp l28 and first reflecting mirror 140 are secured to first support frame 150 slidably mounted on a pair of suspending rods 148a and 148b which extend substantially horizontally in -the upper half portion of -the space between fron-t vertical base plate 101 and rear vertical base plate 1030 Second reflecting mlrror 142 is secured to second support frame 152 mounted slidably on suspending rods 148a and 148bo In-mirror lens 144 is : : :
secured at a fixed posi.tion between partltloning plates 116 and 1340 ~hird reflecting mirror 146 is secured to a predetermined position botween partitionlng plates 116 : and 1220 ; First support frame 150 to which lamp 128 and first reflecting mirror 140 are secured is reciprocable between the position shown by the solid line in Figure 9 and the position shown by the two-dot chain line ln Figure 9g and second support frame 152 to which second reflecting mirror 142 is secured is reciprocable at a speed half of the speed of first suppor-t frame 150 between .~ . . . . .

the position shown by the solid line and the position shown by two-dot chain line shown in Figure 9O
By particular reference to Figure 10, a drive mechanism for driving first support frame 150 and second support frame 152 in thi.s manner will be describedO In rear vertical base pla-te 103 (see Figure 11) provided in housing 100, pulley 156 to be driven by a motor via a drive sys-tem to be described, and first follow-up pulley 158 and second follow-up pulley 160 are rotatably providedO
l~ird follow-up pulley 162 is rotatably provided in second support frame 1520 First wire 164 and second wire 166 are wrapped around these pulleys in the following mannerO
~irst wire 164 which is fixed to rear vertical base plate 103 and ex-tends from one end 164a is first wrapped about fi~st follow-up pulley 158, then about pulley 156 and further about second follow-up pulley 160, and other end 164b is fixed to first support frame 150O Second wire 166 fixed to rear vertical base plate 103 and extending from one end 166a is wrapped about third follow-llp pulley 162, and other end 166b is fixed to first suppor-t frame 1500 rrhus~ when pulley 156 is rotated in the direction of arrow ~ at a fixed speed, firs-t support frame 150 is moved in the directi.on of arrow E at the peripheral speed of pulley 1560 Second support frame 152 is moved in the direction of arrow E at a speed one half of the above peripheral speed by the principle of tackleO When pulley 156 is rotated in the direction of arrow F at a fixed speed, first support frame 150 is moved in the direction of arrow A at the same peripheral speed as pulley 156, ~. . , ~.

~.3LZ~)Og3 and second suppor-t frame 152 is moved in the direction of arrow F at a speed half of t:he peripheral speed of pulley 156 in accordance with the principle of tackleO
Optical system 22 successively scans the image of the original placed on transpare~t plate 102 and pro-jects it onto the surface of drum 108 while firs-t support frame 150 moves from the position shown by the solid line to the position shown by the two-do-t chain line at the same moving speed as the moving speed of the periphery of rotary drum 108 and second support frame 152 moves from the position shown by the solid line to the position : shown by the two-dot chain li.ne at a speed half of the moving speed of the periphery of rotary drum 1080 ~irst suppor-t frame 150 and second support frame 152 may be constructed such that in case of need, they can be returned at ~`aster speeds than their moving speeds mentioned above from the position shown by -the two-dot chain line to the position shown by the solid lineO
~he path of the reflecting light of the original illuminated by lamp 128 secured to first support frame 150 is briefly describedO ~he reflectlng light from the original first passes through transparent plate 102 and reaches first reflecting mirror 1400 It is reflected by first reflec-ting mirror 140, and reaches second reflecting mirror 142 where it is fur-ther reflectedO The reflected light is then reflected onto the mirror within in-mirror lens 144, passes through vertical transparent plate 120, and reaches third reflecting ~irror 1460 It is reflected by third reflecting mirror 146, and reaches the surface of rotary drum 1080 When the original is scanned by lamp 128, first reflecting mirror 140 and second reflect-ing mirror 142 while first support frame 150 and second support frame 152 move, lamp 128 and first reflecting mirror 140 move at the same speed as the peripheral speed of rotary drum 108, whereas second rePlecting mirror 142 moves at a speed half of this speedO Accordingly, through-out the entire step of scanning the original, the optical length from the original to in-mirror lens 144, and the optical length from in-mirror lens 144 to the surface of rotary drum 108 are always maintained substantially constantO If vertical transparent plate 120 is made in the same thickness and of the same material as transparent plate 102 on which to place the originalj the influence ; 15 (io eO ~ the refractive index) of transparent plate 102 on ~: the light path extending from the original to the lens of in-mirror lens 144 becomes equal to the influence ~ (io eO 7 the refractive index) of vertioal -transparent : plate 120 on the light path extending from the lens of in-mirror lens 144 to the surface of rotary drum 1080 Accordingly, the individual elements:of optical system ~ 22 can be positioned wLthout consideration of the effects ~ of transparent plate 102 and ~ertical transparent pla-te ,~ 120 on the light pathsO
In optical system 22 in which first reflecting -~ mirror 14~ and second reflecting mirror 142 move at different speeds along a pair of suspending rods 148a and 148b, the dis-tance be-tween the reflecting mirrors -` changes.~ccording to the positi.on of first support frame 150 :
- 53 ~

: ;

to which first reflecting mirror 140 is fixed and second support frame 152 to which second reflecting mirror 142 is securedO Accordingly~ at the time of ~ixing both ends of each of first wire 164 arld second wire 166 at fixed positions or at th~e time of exchanging the used ~Jires 164 and 166, it is considerably difficult to position first support frame 150 and second support frame 152 in a fixed relation on suspending rods 14-8a and 148b so that the optical length from the original to in-mirror lens 144 is equal to the optical length from in-mirror lens 144 to the surface of rotary drum 108O
However, according to the optical system 22 in the preferred embodiment o~` the electrostatic copying apparatus of this invention, first support frame 150 and second support fral~e 152 mounted slidably on suspending rods 148a and 148b can be positioned in a fixed relation very easily and rapidly, and -the two eDds of first wire 164 and/or second wire 166 can be fixed at predetermined , i~ ~ positionsO ~
In optical sys-tem 22 in accordance with the preferred embodiment of -the electro~statio copying appa-:~ ratus of this invention, a part of first support frame 150, for example block portlon 150a having a hole through which rod 148b extends, and a part of second support frame 152, for example block por-tion 152a having a hole through which rod 148b extends, are formed in a predetermined dimensionO ~hese block portions 150a and 152a cooperate with a suitable stopping member~ for example support , . bracket 168 (see Figures 8 and 11) secured to the right-hand

- 5 .~

z~o93 end portion of rear vertical base plate 103 and support-ing the right-hand end portion of suspending rod 148b, thereby to ~orm a positioning means for first support frame 150 and second support frame 1520 Specifically, optical system 22 shown in the drawings is constructed such that first support frame 150 and second support frame 152 can be suitably positioned in a fixed relation by contacting the right-hand end of block portion 152a of second support frame 152 with the left-hand end of support bracket 168 and contacting the right-hand end of block portion 150a of firs-t support frame 150 with the left end of block portion 152a of second support frame 1520 Accordi.ngly, in assembling the apparatus9 block portion 150a of first support frame 150, block portion 152a of second support frame 152 and support ; bracket 168 are contacted with each other as described : hereinabove, and both ends of first wire 164 and/or second wire 166 are fixed to predetermined positions of rear vertical base plate 103 and first support frame 1500 ~hus, first support frame 150 and second support frame 152 are held so that they can move in a fixed relation to each ;~ otherO Then~ first support frame 150 and second support .~ frame 152 can be moved to the starting position of scanning ::
.. shown,for example,by the solid l.ine in ~igure 9O
According to the preferred embodiment of the . electrostatic copying apparatus in accordance with this . invention, optical system 22 is constructed such tha-t the positioning of in-mirror lens 1~ namely focus adjustment, can be performed-more easily than in ;:`
"
, , ,;

conventional optical systemsO
According -to the prior techniques, the posi-tioning of in-mirror lens 14~ is performed by first observing an image projected on the surface of rotary drum 108 to determine whether the image of the original placed on transparent plate 102 has been formed correctly on the surface of rotary drum 108, and then meticulously adausting the posi-tion of in-mirror lens 1~ according to the result of observationO It is relatively difficult however to observe the surface of rotary drum 108 while meticulously adjusting the position of in-mirror lens 144, because rotary drum 108 is disposed substantially centrally in housing 100 and the various devices provided around the drum willblock vision beyond the s-~rface of rotary drum In optical system 22 in accordance with the : preferred embodiment of the electros-tatic copying appa-ratus of this invention, a semi-transparent image-focusing plate (member 170 shown by the two-dot chain l1ne in Figure 9) made, for example, of ground glass can be tem-porarily fixed at a position spaced from the surface of :~ third reflecting nirror by a length same as the optical : length extending from the surface of third reflecting mirror 146 to rotary drum 1080 In this optical system ~2, in-mirror lens 144 can be positioned relatively easily by temporarily fixing image focusing plate 170 before the righ-t-hand side wall of housing 100, partitioning plate 126 and third reflect-ing mirror 146 are mountedO By so doing, the image of ,, ., ., .. , . ;-,. ;. , ~Z~)~93 the original placed on transparent plate 102 is projected onto image focusing plate 1700 Since image-focusing plate 170 is positioned near the right-hand side wall of housing 100 (the wall is not mounted when positioning in-mirror lens 144) and is made of a semi-transparent material such as ground glass, the image of the original projected on the focal plane of image focusing plate 170 can be observed easily from outside the right-hand side wall of housing 100 (in Figure 9)O Accordingly, the position of in-mirror lens 144 can be easily adjusted meticulously while observing the image of the original projected onto the focal plane of image focusing plate 1700 ; Image focusing plate 170 is mounted at such a position ;~ that the optical length from the surface of third reflecting mirror 146 to be pro~ided later to the focal plane of image focusing plate 170 is equal to the length from the surface of third reflecting mirror 146 to that portion of rotary drum 108 onto which the.image of the original will be proaected~
: ~
Hence, if in-mirror lens 144 is fixed correctly at a posi-tion at which the image of the orig1nal is correctly formed on the focal plane of image focusing plate 170, and third reflecting mirror 146 will be later mounted~ the image of the original can be correctly formed on the surface of rotary drum lO~o After in-mirror lens 144 has been positioned and fixed, image focusing plate 170 is removed, and then third reflecting mirror 146, partitioning plate 126 and the right-hand side wall of housing 100 are mountedO
~he space between partitioning plates 126 and 116 in which image focusing plate 170 is temporarily fixed is utilized as a space for accommoda-ting electrical means for opera-ting and controlling various component parts of the electrostatic copying apparatusO
Rotar~T drum and various device~rovided arolmd it Referring to :E`igures ~3~ 9 and 12 to 149 rotary drum 108 and corona discharge device 20, developing device

6, corona discharge device 369 static eliminating lamp 32 and cleaning device 34 disposed around rotary drum 108 10 : are described below in detailO
In a preferred embodiment of the electrostatic copying apparatus of this inven-tion, a support generally shown at 172 is secured -to fron-t vertical base plate 101 and rear vertical base plate 103 centrally beneath parti-tioning plate 116 in a manner such -that it is freely slidable in the forward and rearward directions (the direction perpendicular to the sheet surface of :Figure 9)O
~o support 172 are secured rotary drum 108, corona dis-charge device 20 for charging, developing device 6 and cleaning device 34O
Referring to :Figures 12 and 139 support 172 includes vertical front plate 17L~ and vertical rear pla-te : 176 arranged substantially parallel to each o-ther with a distance therebe-tween corresponding nearly to the dis-tance between front vertical base plate 101 and rear vertical base pla-te 103~ and a pai:r of horizontal members 178 and 180 which extend from both side portions of vertical .- front plate 174 substantially horizontally over vertical rear plate 1760 Preferably~ support 172 further includes -- 5:3 --~.'Z~93 cover 181 which is removably secured and covers the left portion of -the top of support 1720 Guide rolls 182 and 184 are mounted on the rear e~ds of horizontal members 178 and 180 respectively which extend beyond vertical rear plate 176~ Guide rail 188 having groove 186 at its bottom surface is secured to horizontal member 178a Flat guide rail 190 is secured to horizontal member 1800 Furthermore, notch 192 is provided at the upper edge of horizontal member 178 near its forward end~
~ront vertical base plate 101 has opening 1J5 having a shape corresponding to the shape of support 172 so that support 172 can be set at a predetermined operat-ing position through opening 1950 A pair of channel-like guide rails 194 and 196 (see ~igures 14, 13 and 9) are fixed to front vertical base plate 101 and rear vertical base plate 103~ Guide rails 194 and 196 which extend rearward from front vertical base plate 101 over rear vertical base plate 103 receive and guide the guide rolls 182 and 184 mounted on the rear ends of horizontal members 178 and 180 of support 172~ Guide roll 198 adapted to be engaged with groove 186 of guide rail 188 and guide roll 200 adapted to be engaged with the bottom surface of guide rail 190 are rotatabl~ mounted respectively on the front vertical base plate 101 ~ear the forward ends of guide rails 194 and 1960 ~t -the upper portion of guide rail 194 near its forward end is provided locking means 202 (see ~igures 11 and 13) which coopera-tes with notch 192 of horizontal member 178~ ~ocking means 202 secured to partitioning plate 116 may be of any known type, and -, . ~, ,, . ~ ~, ,~ o~3 includes an engaging member (not shown) which is elasti-cally restrained by an elastic means such as a spring, extends downward throu~h the openings formed in parti-tioning plate 116 and guide .rail 194, and comes into engagement with notch 192, and operating part 204 which by hand operating, can lift the engaging memberO
It will be appreciated therefore that support 172 is mounted so that it is slidable in the forward and rearward directions (the direction perpendicular to the sheet surface of ~igure 9) through opening 195 formed in front vertical base plate lOlo Briefly stated, support 172 is mounted slidably by engaging guide rolls 182 and 18~ with guide rails 194 and 196 and guide rails 188 and 190 with guide rolls 198 and 2000 When support 172 is inserted rearward and reaches the operating position (io the position at which vertical front plate 174 is situated substantially on the same plane as front vertical base plate lOl,and vertical rear plate 176 is situated adjacent rear vertical base plate 103)9 locking means:202 and notch 192 cooperate to lock support 172 releasablyO ~o pull out the support forward and lf desired, remove it from housing 100, operating part 204 of locking means 202 is operated to release the cooperation of locking means 202 and notch 192, and support 172 is caused to slide forward~
Rotary drum 108~ corona discharge device 20, developing device 6 and cleaning device ~4 are mounted on support 172 described aboveO
Referring to ~igures 12 to 15? the mounting of rotary drum 108 on support 172 will be describedO In each .
", . , ~ .

~ 3 of vertical front plate 174 and vertical rear plate 176 of support 172 is formed a slot 208 extending upward from the lower edge of each of plates 174 and 176 to its central part in a somewhat inclined manneru Slot 208 is adapted to receive shaft support member 218 rotatably fitted in each end portion of shaft 206 of rotary drum 108 through a suitable means such as ball bearingsO
Shaft 210 is rotatably secured to vertical front plate 174 and vertical rear plate 176 of support 172~ and rotary drum-holding lever 212 for supporting shaft support member 218 in place is secured to each of the forward end of shaft 210 which projects forward beyond vertical front plate 174 and the rear end of shaft 210 which projects rearward beyond vertical rear plate 1760 Rotary drum 108 can be mounted on, and removed from, support 172 in the following mannerO ~o mount rotary dru~ 108 on support 172~ holding lever 212 i s turned clockwise by a suitable angle from the position shown in ~igure 13 to position it at a point which does not interfere with slot 2080 ~hen, rotary drum 108 is fitted into support 172 from below~ and shaft supporting members 218 fitted in the end portions of shaft 206 are inserted into slots 2080 ~olding levers 212 are then turned to the positions shown in Figure 13~ and fixed in position by such a means as screws 213a As a result, shaft supporting member 218 fitted in both end portions of shaft 206 of rotary drum 108 is supported in a sub-stantially circular hole defined by -the hook-like forward end of holding lever 212 and the semi-circular upper end , ~ 61 ~

`:

~ ` 1iL~9;~

of slot 2080 ~o remove rotary drum 108 from support 172, the fixing of holding levers 212 by means such as screws 21~ is released, and holding levers 212 are turned clock-wise from the positions shown in Figure 130 ~he rotary dr~ 108 is moved downward along slots 2080 ~o the rear-most end of shaft 206 of rotary drum 108 is fixed joint 217 which is adapted to be drivingly connected to join-t 216 rotatably mounted on rear vertical base plate 103 (joint 216 is rotated by a motor through a drive system to be described below in detail)O Joints 216 and 217 may be of any known type, and are adapted to be connected to each other when their angular positions are in agreement as prescribedO To the forward end portion of shaft 206 is fixed a grip knob 220 which the operator can grip when pulling out or removing support 172 from housing 100 or when mounting or removing rotary drum 1080 Grip knob 220 ~see Figure 8 also) is connected to shaft 206 via a known one-way clutch placed therein, and can rotate rotary drum 108 and its shaft 206 only when tu~ned l~n a predetermined rotating direction of the rotary drum 108 (io e~, the direc-tion shown by arrow B --- see Figure 9)0 Since joints 2I6 and 217 are connected to each other when thelr angular positions are in agreement as prescribed, joints 216 and 217 must be brought into agreement by rotating rotary drum 108 and shaft 206 when mounting rotary drum 1080 As wlll be described in detail below, developing device 6 and developer-holding member 50 of cleaning device 34 are adapted to be rotated when rotary drum 108 is rotatedO
If, therefore, rotary drum 108 is adapted to be rotated .

~Z~93 also in a direction opposite to the prescribed rotating direction (the direction shown by arrow B), developing device 6 and developer-holding members 8 and 50 of cleaning device 34 are rotated in a direction opposite to the predetermined rotating direction, and it is likely therefore that the developer contained in developer supplier 14 of developing device 6 will abnormally over-flow from it, or build up on the surface of the rotary drumO However, since in rotary drum 108 shown in the drawings, securing of grip knob 220 to the forward end of shaft 206 is through the one-way clutch, even when by inadvertence in mounting rotary drum 108, grip knob 220 is rotated in a direction opposite to the predetermined direction~ rotary drum 108 rotates onLy in the predetermined direction, and developing device 6 and cleaning device 3 are free from such adverse effects as described aboveO
~ orona discharge device 20 for charging is mounted detachably on support 172 by fitting it into opening 222 formed in vertical fron-t plate 1740 Mounting and detaching of corona discharge device 20 can be very easily performed by gripping grip knob 224 provided at its front end~ Member 225 which constitutes a shield case for corona discharge device 20 is fixed at a position between vertical front plate 174 and vertical rear plate 176 where corona discharge device 20 is -to be providedO
Developing device 6 which is preferably of the type described in detail with reference to ~igure 2 i5 also mounted on support 1720 Developer supplier 14 in developing device 6 is fixed in place by a suitable means such as positioning pin 226 to be inserted into the front plate and the rear plate of supplier 14 through vertical front plate 174 and vertical rear plate 176 of support 1720 Furthermorej as described in detail with refere~ce to Figure 2, developer-holding member 8 in the form of a hollow cylindrical sleeve having a roll-like permanent magnet disposed in it is pivotably supported by bearing member 227 provided at each of the front and rear plates of developer supplier 140 Pin 229 fixed to bearing member 227 is received in adjusting piece 228 adjustably mounted on vertical front plate 174 and vertical rear plate 176 of support 1720 ~hus, the distance between the surface of rotary drum 108 and the surface of developer-holding member 8 can be meticulously adjustedO ~he entire developing device 6 consisting of : developer-holding member 8 and developer~supplier 14 as an integral uni-t can be de-tached from support 172 by merely detaching the pin 229 fitted ln the bearing member 227 and the positioning pin 2260 :A developer supply : 20 opening positioned at the top of developer supplier 14 ; ~ is~situated at the left end of the top surface of: support ~: ; : 172, and therefore, is open without being covered by cover 181 (Figure 12)o A~brush length-adjusting member pre~
ferably of the type descrlbed hereinabove~with reference to Figure 2 is secured to developer supplier 140 ; ~ Support 172 further has cleaning device 34, preferably of the structure described in detail herein-above with reference to ~igure 7, mounted on ito ~he shaft for developer-holding member 50 of cleaning device ~:
-- 6L~ --, ............. . .... . .

34 is rotatably supported by the adjusting piece 230, and adjusting piece 230 is adjustably mounted on vertical from plate 174 and vertical rear plate 1760 ~ence, by adjusting the position of adjusting piece 230, ~he clearance between the surface of rotary drum 108 and the surface of developer-holding member 50 can be meticulously adjustedO Furthermores developer~holding member 50 can be detached from support 172 by merely detaching adjusting piece 230 from vertical front plate 174 and vertical rear plate 1760 Developer receiver 58 of cleaning device 34 is fixed in position between vertical front plate 174 and and i-ts forward end portion is placed on frame member 54 which, together with the lower edge of vertical front plate 174, defines a receiving opening of d.eveloper-receiver 580 A brush length-adjusting member of the type described in detail hereinabove with reference to Figure 7 (not shown in Figure 13) is secured to frame member 54O Receptacle 58 which is inserted through the receivi.ng opening defined at its front por-tion and placed on frame member 54 can be easily mounted or detached by grasping grip ~nob 232 provided at its fron-t endO
~lectrostatic eliminating lamp 32 and corona discharge device 36 for transfer are moun-ted dlrectly on front vertical base pla-te 101 and rear vertical base plate 103 at predetermined positions around rotary drum 1080 As most clearly shown in Figure 14~ electrostatic eliminat-ing lamp 32 is fixed to front vertical base plate 101 and rear vertical base plate 103 by a suitable means such as screws at a predetermined position wi-th respect to the , . .. .
.' ' . -; '' , ~ . ' : ' , surface of rotary drum 108 to be mounted on support 1720 Corona discharge device 36 for transfer is mounted detachably at a predetermined position with respect to the surface of rotary drum 108 to be mo~mted on support 172 by being fi-tted into notch 234 of a prescribed shape formed in front vertical base plate 101 and rear vertical base plate 1030 Corona discharge device 36 can be very easily mounted and detached by grasping grip knob 236 provided at its front endO
As best shown in Figure 14, nail 40 for peeling a receptor sheet i5 fixed to rear vertical base plate 103 via fixing bracket 238 at a position which is adjacent corona discharge device 36 downstream of the moving direc-~:~ tion of the surface of rotary drum 108 and is near the rear ~: 15 end of corona discharge device 36 for transferO ~ail 40 : ; serves to peel a receptor sheet from the surface of rotary drum 103 having a toner image so as to send the receptor sheet having the toner image to fixing device 28 through a passage defined by receptor~sheet conveying roller 240 and receptor sheet guide plate 420 ~he receptor sheet peeled off from rotary:drum 108 by the action of peeling nail 40 undergoes the action of peel roller 241 (see igure 19) which cooperates~with conveying roller 240 and fed onto guide plate 420 To peel the firmly adhering receptor sheet from the surface of rotary drum 108 exactly, ~: it is preferred to make peeling nail 40 such that its forward end 40a is engaged with the edge of the receptor sheet projecting from the surface of rotary drum 1080 ~his can be achieved by making the rear end of rotary drum :

, ,, , ~: . ;.. , " . . . ... .

g3 108 smaller in diameter than the remainder (the surface of the smaller-diameter portion is not u-tilized for the formation of an electros-ta-tic latent image and a toner image), or by somewhat dec.reasing the width of rotary drum 1080 In the electrosta-tic copying apparatus of the type described hereinabove for performing the electrostatic copying process described above by reference to ~igure 5, the devloper contained in developer supplier 14 is con-sumed as the copying process is perforrnedO Hence, the developer must be supplied occasionally to supplier 140 ~urthermore, as the copying process proceeds~ the developer removed from the surface of rotary drum 108 builds up in receptacle 58 of cleaning device 340 Hence~ the developer in receptacle 58 must be occasionally recoveredO On the other hand, as described in detail hereinabove with re-ference to ~igure 2, in order to perform the developing step in good condition, it is important to maintain dis-tance d2 between the surface of developer-holding member 8 and the surface of rotary drum 108 and distance d1 between the developer-holding member 8 and the forward end of brush length-adjusting member 16 secured to developer supplier 14 at suitable valuesO Furthermore, as already described with reference to ~igure 7, to perform the cleaning step in good condition, it is important to main-tain dis-tance d4 between the surface of developer-holding member 50 and the surface of rotary drum 108, and distance d5 between the surface of developer-holding member 50 and the forward end of brush length-adjusting member 56 at ~- ~" ., . ~ : :
- ; . .

`' llZ~1093 suitable valuesO
In the preferred embodiment of the electrostatic copying apparatus of -this invention described above, developing device 6 together with rotary drum 108 is mounted on support 172 which is mounted on front vertical base plate 101 and rear vertical base plate 103 in a manner such that it is slidable in the forward and rearward di-rections9 and the supply opening of developer supplier 14 :; of developing deivce 6 is opened upwardO Hence9 supplying of the developer -to developer supplier 14 can be performed by merely pulling support 172 forward and feeding the developer through the supply openingO ~hus, it is not : necessary to construct the apparatus such that for supplying the developer 7 the en-tire developing device 6 is caused to sllde forward wi.th respect to rotary drum 108, or developer supplier 1l~ to slide forward:with respect to developer-holding member~8 of~developing device: 60 If .
~ ~ the appara-tus is constructed in this way as in conventional : electrostatic copying apparatus9 it is extremely~dlfficult, 20~ if not impossibl.e, to maintain distance d2 exactly at a predetermined value~ and distance d2 is likely to~be :: ~
~ : changed by the sliding of`the en-tire developing device.6 or ~:
developer suppIier~14 ln the forward and rearward direc-: tionsO

In the preferred embodiment of the electrostatic ~:~ :: copying apparatus in accordance with this invention, clean-~: ing device 34 is also mounted. on support 1727 and only ~ . .
the recep-tacle 58 of cleaning 34 is adapted to be moved forward of suppor-t 172 and puIled out~ Hence9 the developer : - 68 ,.. ~ . ~ ," , ~ ; . . ,. . - - : .

~L~2~)gg3 that builds up in receptacle 5~ can be rapidly and easily recovered without any adverse effect on distance d4 by merely pulling out receptacle 58 forwardO There is no need to construct the appara-tus such that in recovering the developer, the entire cleaning device 34 may slide forward wi-th respec-t to rotary drum 108, or frame member 54 having brush length~adjusting member 56 fitted thereto may slide forward with respect to developer-holding member 50 of cleaning device 34O Accordingly, distance d4 can be maintained exactly at a predetermined valueO
~ urthermore7 in the preferred embodiment of the electrostatic copying apparatus of this invention, as can be easily understood from ~igures 9 and 14, when support 172 is pulled out by forward sliding, a transfer station having corona discharge device 36 and a receptor sheet passage nearby (the receptor sheet conveying system and the receptor shee-t passage in -their en-tirety will be described hereinbelow) are directly exposedO lhus,any receptor sheet which jams up at these portions can be easily removedO
Since corona di.scharge device 20 is mounted easily detachably on suppor-t 172 ànd corona discharge device 367 on front vertical base plate 101 and rear vertical base plate 103, they can be very easily repaired, cleaned or replaced in the event they are damaged, cut off or soiledO Support 172 having developing device 6, cleaning device 34 and corona discharge device 20 mounted on it7 when pulled out forward to a predetermined position, is blocked by a suitable blocking member to chec~ further " - , ................... .
.. . .
, . : : .;

~lZ~93 forward movement and thus to prevent inadvertent dropping of suppor-t 1720 It is also possible to construct the apparatus such that support 172 can be completely detached ~rom housing 100 by somewhat lifting it after it has been pulled out forward to a predetermined positionO
Support 172 completely detached from housing 100 in this way can be placed temporarily on an auxiliary frame (not shown) which can hold support 172 by engagement with bottom surfaces of guide rai.ls 188 and 1900 ~igure l~A shows a modified example of a support -: which is mounted on front verti.cal base plate 101 and rear vertical base plate 103 so that it is slidable in the forward and rearward directions (iOeO, the direction perpendicular to the surface of the sheet surface of ~igure 9) and a rotary drum~ a developing device and a cleaning device which ~re mounted on the supportO
The support shown generally at 472 in the modified exampIe shown in ~'igure 13A includes vertical front plate 474 and vertical rear plate 476 which are disposed substantially paral.lel to each other with an interval therebetween corresponding to the distance between front vertical base pIate 101 and rear vertical base plate 103~ and a pair of channel-like horizontal members 4-78 and 480 which extend substantialIy horizontally from both side portions of vertical front plate 474 beyond vertical rear plate 4760 Horizontal members 478 and 480 of suppor-t 472 are slidably engaged respectively with a pair of guide rails 494 and 496 which are slidably received in a pair of guide rails 493 (only one of them is shown ~ 70 -,.. , .:. : : , in the drawing) extending backward from front vertical base plate 101 (no-t shown in ~igure 13A) beyond rear vertical base plate 1030 ~his causes support 472 to be mounted on front vertical base plate 101 and rear vertical base pla-te 103 so that it is slidable in the forward and rearward directionsO Loc~ing means 502 of` any known type is provided in the inside upper edge portion of vertical front plate 474 of support 4720 Locking means 502 is elastically and releasably engaged with part 195a of opening 195 of front ver-tical base plate 101 when suppor-t member 472 is inserted and reaches an operating pusition where vertical front plate 474 is si-tuated substantially on the same plane as front vertical base plate 101 and vertical rear pla-te 4-76 is adjacent rear vertical base : 15 plate 1030 ~otary drum 108, corona discharge device 20 for charging, developing device 706 and cleaning device 734 . are mounted on suppor-t 4720 Rotary drum 108 shown in ~igure 13A is con-structed such that cylindrical body 409 having a photo-sensitive material on its surface can be easily detached ~ as requiredO Specifically9 rotary drum 108 sho~m in ; ~'igure 13A has support shaft 406 and a palr of discs 410 and - 412 rotatably mounted on support shaft 406 through bearing : 25 means 407~ Discs 410 and 412 are connected to each other by a plurality (three in the drawing) of stays 414 arra~ged :~ in spaced apart relationship in the circumferential direc-tionO ~o disc 412 is fixed gear 344 which is to mesh with gear 354 of developing device 706 and gear 348 of cleaning ,~
~ _ 71 -"
. , , , .
;'''' ' ' ' ' ' ~ ~ "'" ' ' ' ~, : ~1'~093 device 734, as will be described in detail hereinbelow by reference to ~igure 190 Cylindrical body 409 having photosensitive member 2 is fitted with discs 410 and 412 and stays 414~ inserted in an annular recess formed in the inside part of the end of cylinder 40~, and held in position by disc 416 fixed -to disc 410 by a plurality of screws 4150 In the modified example shown in ~igure 13A in which support shaft 406 is supported on bearing means 407, it is not necessary to maintain the linearity of the axis of shaft 406a severely over its entire lengthO In other words, the shaft is easy to make since i-t is sufficient to finish only that part of shaft 406 at which to locate beari.ng means 407 within thc range of predetermined linearityO
Rotary drum 108 of the above construction is detachably mounted on support 472 by de-tachably fixing ~ support shaft 406 to vertical fron-t pl:ate 474 and vertical : ~ rear plate 476 of support 4720 In each of vertical front : plate 474 and vertical rear pla-te 476, slot 408 extending upwardly from the lower edge of each plate to its center ~ in a somewhat inclined manner ls formedO~ Each slot 408 ; ~ has part 408a having a width smaller than the diameter of support shaft 406 by a predetermined dimension and circular part 408b having its center somewhat deviated wlth respect to the longitudinal axial line of this part ; 408a and having substantially the same diameter as the diameter of suppor-t s~aaft 406u Chord-like groove 405 having a width corresponding to each of vertical front plate 474 and vertical rear plate 476 is formed at both : , . ~ ~ . ~, .. .

" ~ `
~iZ0~)93 end portions of support shaft 4060 Notch 404 is formed at the forward end por-tion of support shaft 406 to indicate the position of groove 405O ~o mount rotary drum 108 on support 472, support shaft 406 is maintained in the con-dition shown in Figure 13A in which its grooves 405receive vertical front plate 474 and vertical rear plate 476 of su.pport 472 respec-tively, and inserted into slot 408 up to -the part 408b via par-t 408aO ~hen, support shaft l-~06 is turned counterclockwise in Figure 13A to direct grooves 405 at both its ends downwardO In the next place, stopper 413 having projecting portion 413a to be engaged with groove 405 is fixed only to vertical front plate 474 by means of screws 417 to block the rotation of support shaft 406, thereby to mount support shaft 406 and rotary drum 108 exactly at predetermined posltions of support 4720 Rotary drum 108 can be detaohed from support :472 by reversing the above:procedureO When rotary drum 108 has been mounted at a predetermined position~of support 472 and support 472 is inserted a-t a predetermined position ~(iOeo~ the positlon at which vertical front~plage:474 is situated on substantlally the:same plane~as front vertlcal ;; base plate 101 and vertical rear pl~a~te:~476 is adjacent rear vertical base plate 103), gear 3~:of~rotary drum 108 is drivingly connected to a drive sys~em to be describedO
~ ~he driving connection of gear 344 t;o the dri~e system can : ~~ be achieved, for exampl:e, by pl-votably supporting a shaft (not shown) to be rotated by the drive system on rear vertical base plate 103, and fixlng a gear (not shown) to be in mesh with gear 344 at the forward end portion of this slla~t which extends beyond vertical rear plate L~76 o In rotary drum 108 shown in ~i.gure 13A, the cylindrical body 409 has at its both ends par-ts 409a and 409b having no photosensitive member 2, and small-diameter part 409c adjacent part 409aO The small-diame-ter part LL09c is positioned corresponding to peeling nail 440 fixed -to the inside surface of vertical front plate 474O
Peeling nail 44~ has the same function as peeling nail 440 already described hereinabove, and acts *o peel off a firmly adhering transfer sheet from the surface of rotary drum 1080 In the embodiment shown in ~igure 13A, peeling nail 440 is fixed to the inside surface of vertical front plate 474O Accordingly~ a peeling roller (not shown in ~igure 13A) which acts cooperatively with peeling nail 440 is moun-ted not on rear vert~cal base plate 103 but on front vertical base plate lOlo : ~orona discharge device 20 for charging, same as in the embodiment described hereinabove with reference to F:gures 12 and 13, is detachably mounted on support ~.
. 472 by inserting it into the opening formed in vertical . , ~ front plate 474O
.~ Developing device 706 shown in ~igure 13A includes '!' developer supplier 7-1.4? developer-holding member 708 in 25 the form of a hollow cylindrical sleeve fixed to the front and rear plates of developer supplier 714, and a roll-like permanent magnet (not shown) rotatably mounted by a suit-: able bearing within developer-holding member 708O In .~
developing device 70~ shown in ~igure 13A, unlike developing _ 7L~ _ .. ...

)093 device 6 shown in Figure 23 developer-holding member 708 remains stationary, and t~e permanen-t magnet inside it .rotatesO ~he developer fed from developer supplier 714 onto the surface of developer-holding member 708 is moved over the surface of developer-holding member 708 by the rotation of the rol]-like permanent magnetO ~he roll-like permanent magnet is rotated by the driving force transmitted by gear 354 fixed to a shaft (not shown) for the roll-like permanent ~agnet which extends through support shaft 707 integrated with developer-holding member 7080 ",/~

~Z~ 3 Developing device 706 of the above construction is detachably mounted on support 472 by inserting auxiliary holdlng pins 715 fixed to the front and rear plates of deiveloper supplier 714 into slots 444 formed in vertical front plate 474 and vertical rear plate 476 of support 472, inserting both end portions of support shaft 707 for developer-holding member 708 into slots 446 formed in vertical front plate 474 and vertical rear plate 47h, turning the stopper 448 (made preferably of an elastic material) from the posi-tion shown by the solid line to the position shown by the one-dot ~ chain line, putting it on a pin and fixing it there to hold ;. support shaft 707 in slots 4460 .Accordingly~ both developer supplier 714 and developer-holding member 708 can be removably mounted on support 472 ver.y easilyO ~he distance between the surface of rotary drum 108 and the surface of developer-holding mamber 708 is prescribed as desired by contacting a . pair of rings 711 rotatably mounted on both end portions of .; support shaft 707 Vla bearing 709 and having a dlameter larger than the diameter of developer-hoIding member 708 .-~ 20 by a predetermined dimension, wlth parts 409a and 409b at both `.~ ends of rotary drum 108.
leaning device 734 illustrated in ~igure 13A
includes support frame 754, developer-holding member 750 : in the form of a hollow cylindrical sleeve fixed to support .. ~.; 25 frame 750, roll-like permanent magnet 749 rotatably mounted~ within developer-holding member 750 by a suitable bearing .-~ , means (not shown)~ and developer receiver 7580 In cleaning device 734 of this structure, substantially same as in developing device 706, developer-holding member 750 remains .~ , _ 76 ': ~

, .

:
~oO93 stationary, and magnet 749 is rotated by the driving force transmitted by gear 348 fixed to a shaft (not shown) for magnet 749 which extends through the inside of support shaft 751 integrated with developer-holding member 750O
Cleaning device 734 of the construction described above is detachably mounted on support 472 in the following mannerO Auxiliary holding pins 755 fixed to the two ends of support frame 754 are inserted into slots 482 formed in vertical front plate 474 and vertical rear plate 476.
portion of support shaft 751 which is near its each end is inserted into slot 484 formed in each of vertical front plate 474 and vertical rear plate 476, and each of stoppers 486 preferably made of an elastic material is turned from the position shown by the solid line to the position shown by the one-dot chain line, put on a pin and fixed there to hold support shaft 751 withi.n slots 484O ~s a result, both support : frame 754 and developer-holding member 750 fixed to:it are detachably mounted on support 472 very easilyO ~he distance between the surface of ro-tary drum 108 and the surface of developer-holding member 750 is s0t as prescribed by contacting ~: a pair of rings 752 rotatably~mounted through bearings 753 on the end portions of support shaft 751 and having a diameter ~: ~: larger than the diameter of developer-holding member 750 by :: ~
a predetermined dimension, with parts 409a and ~09b at both end portions of rotary drum 108 at which no photosensitive material 2 is present~ Receptacle 75a is detachably mounted on support frame 754 by bringing ~-shaped flange 759 formed at its one edge portion into engagement with stay 761 fixed to suppor-t frame 754, and placing the bot-tom surface of ,~ ,. . .

receptacle 758 on a suitable support member (not shown) which projects fro~ the inside surface of support frame 7540 Hence, as required, the entire cleaning device 734 can be removed from support L~72 with receptacle 758 remaining attached to support frame 7540 Or receptacle 758 alone can be very easily detached from support 472 independently of suppo~t frame 754 and developer-holding member 750 fixed to it (iOe~, without removing the entire cleaning device 734)o ~his permits very rapid and easy inspection and maintenanceO
Obviously, developing device and the cleaning device in the preferred embodiment of the electrostatic copying apparatus of this invention described above can be fixed to, and de~ached from, the support very easily.
Rec~tor sheet co~ n~system : 15 ~he receptor sheet conveying system 112 is described with reference to Figures 9, 16, 17A and 17~o Receptor sheet conveying system 112 for conveying a receptor sheet consists of a cassette receiving section for receiving a part of paper cassettes llOa or llOb, and a receptor sheet conveying system for conveying a receptor shee-t stacked in cassette llOa or llOb to receiving tray 30 through a transfer station having corona discharge device 36 for transfer disposed in it and a fixing station having fixing device 28 disposed in it.
First, the cassette receiving section is described with reference to ~igures 16, 17~ and 17Bo Paper supplying cassettes llOa and llOb differ from each other in their own sizes and in the sizes of receptor sheets stacked therein (for example, cassette llOa contains receptor sheets with a .. ~ ... . . .

)093 size of JIS-B5, and cassette llOb contains receptor sheets with a size of JIS-~4)o Otherwise, their constructions are substantially the same, and the cassette receiving section for receiving a part of cassette llOa is substantially the same as the receiving section for receiving a part of cassette llObo ~he following description, therefore, is directed mainly to paper supplying cassette llOa and the cassette receiving section for receiving ito ~he paper supplying cassette llOa is composed of substantially rectangular parallelpipedal case 242a with an open -top, and case 242a includes auxiliary bottom plate 244a made of a relatively rigid material such as cardboard, metal or synthetic resin and layer 246a of receptor sheets of a predetermined size (for example, ~5)0 In Figure 16, bottom plate 244a and receptor sheet layer 246a are omittedO
~itting lever-receiving recess 248a is ~`ormed on both sides of case 242a, and opening 250a for receiving receptor sheet-lifting lever 286a is formed centrally near the forward end of the bottom plate of case 242a~0 Nails 252a: for blocking :~ 20 the forward end of receptor sheet are fixed to the- top end of each corner of case 242a at i-ts forward endO Wedge-shaped notch 253a is formed in the upper edge of the forward portion ~: of each side plate of case 242aO ~he operations of fitting ~ : lever-receiving recesses 248a, lifting lever-receiving opening ; 25 250a, blocking nails 252a and notches 253a will be described in detail hereinbelow~
Openings 254-a and 254b are formed on the right-hand wall of housing 100 of the electrostatic copying apparatus to receive paper supplying cassettes llOa and llOb (see , Qg3 Figure 9)O Inwardly of openings 254a and 254b are provided receiving member 256a and 256b (omitted in Figure 16) which act on the front parts of the paper supplying cassettes llOa and llOb to be inserted through these openings 254a and 254bo ~or convenience, one of the receiving members, 256a, is described~ Receiving member 256a has a cassette bottom guiding portion 258a which extends downwardly and inclinedly from a position immediately inwardly of opening :~ 254a toward the inside of housing 100 and guides the bottom surface of paper supplying cassette llOa inserted through opening 254a, cassette end abutting portion 260a which the forward end of paper supplying cassette llOa to be inserted through opening 254a abuts, and receptor sheet guiding : portion 262a which further extends toward the inside of housing 100 from the top end of abutting portion 260a and guides the receptor sheet fed from cassette llOa to the réceptor sheet conveying s~stem, as will be described herein-,.
belowD ~
At a position above cassette bottom guiding portion 258a by a predetermined diStance~from it~ shaft;266a to be rotated selectively in the directlon of arrow E (in the : clockwise direction in ~lgures~16, 17~ and~17B) by~the action ::
of clutch MC3 which may be:an el~ectromagnetic clutch or a : combination of a rotary spring clutch and an~electromagnetlc solenoid is mounted rotatably on front ve:rtlcal base plate 101 and rear vertical base plate 1030 ~ pair of paper feed : rollers 268, for example, are secured to shaft 266aO A pair of stop plates 270a with which wedge-shaped notches 253a formed in the paper supplying cassette llOa come into engagement _ 80 --~IZ~93 are fixed to front vertical base plate lOl and rear vertical base plate lO~ at a position above cassette bottom guiding portion 258a.
Immediately inwardly of receiving member 256a, Shaft 272a is rotatably mounted on front vertical base plate lOl and rear vertical base plate 1030 A nearly fan-shaped positioning member 274a is fixed to one end (the forward end in Figure 16) of shaft 272a. Near shaft 272a is disposed a stop pin 276a fixed to front vertical base plate lOlo A pull spring 278a is set between stop pin 276a and that end of positioning member 274a which is farther away from stop pin 276aO ~ pair of projecting sections 280a and 282a to be engaged with stop pin 276a are formed at that end of positioning ; member 274a which is nearer stop pin 276a, and that portion of positioning member 274a which is between two projecting sections 280a and 282a forms an arc having a predetermined radius of curvature. The stop pin 276a, positioning member 274a and pull spring 278a are constructed such that they operate as follows: -In the state shown in Figures 16 and 17A in~which one projectLng section 280a of positloning member 274a come into engagement with stop pin 276a,;~shaft 272a is urged in the clockwise direc-tion by the elastic action of pull spring ~;~ 278a, and therefore~ shaft 272a is set ln position by the engagement of projec-ting section 280a with stop pin 276a.
If, as described hereinbelow, shaft 272a is turned counter-clockwise in ~igures 16 and 17~ in resistance to the elastic action of pull spring 278a as a result cf operating the paper supplying cassette llOa~ the pull_~pring 278a retracts from its most stretched state and urges shaft 272a counterclockwise Accordingly, shaft 272a is turned by the elastic action of pull spring 278a to the state illustrated in Figure 17B in which other projecting section 282a of positioning member 27L~a comes into engagement with stop pin 276a, and set in position. In other words, s-top pin 276a, positioning member 274a and pull spring 278a are constructed so as to urge shaft 272a elastically to a first angular position at which the projecting section 280a comes into engagement with stop pin 276a (the angular position shown in ~igure 16 and 17A), or to a second angular position at which the pro~ecting section.
282a comes into engagement with pin 276a (the angular position shown in Figure 17~
~o shaft 272a described above are fixed a pair of cassette linking levers 284a with a distance therbetween corresponding substantially to the width of paper cassette llOa.~ When cassette llOa is inserted by contacting its bottom surface with cassette bottom guiding portion 258a of receiving member 256 with shaft 272a being at the first angular position described above~ cassette linking levers 284a are fitted into recesses 248a of cassette llOaO Intermediate between cassette linking levers 284a, receptor sheet-lifting lever 286a is rotatably mounted on shaft 272aO Receptor sheet-lifting lever 286a can extend through opening 250a formed centrally near the forward end portion of the bottom plate of cassette llOa and a notch (not shown) formed in receiving member 256a at a position corresponding to opening 250a~ and can directly act on auxiliary bottom plate 244a and receptor sheet layer 246a placed in cassette llOa~ When shaft 272a is at the first angular position~ lever 286a is held in the position shown in Figures 16 and 17A at which the forward end of lever 286a is retracted from opening 250a. When shaft 272a is turned to the second angular position described above, lever 286a is elastically urged co~mterclockwise in Figures 16, 17~ and 17B (in a direction to lif-t auxiliary bottom plate 244a and receptor sheet layer 246a in cassette llOa) by an elastic means such as spring 288a with one end fitted to shaft 272a and the other end to lifting lever 286aO
It is believed to be already clear from the above description how the paper supplying cassette llOa is inserted into the cassette receiving section and how a receptor sheet is fed from the receptor sheet layer in cassette llOaO ~he mechanism is summarized below, howeverO
~o insert cassette llOa i.nto the receiving section through opening 254a formed on the right-hand wall of housing 100, it is first necessary to contact the bottom surface of cassette llOa with bottom guiding portion 258a of receiving member 256a and insert cassette llOa until its forward end abuts abutting portion 260a of receiving member 256a, -thus attaining the state shown in Figures 16 and 17~o At this time~ shaft 272a is located at the first angular position at which one of proaecting sections 280a of positioning member 274a is in engagement with stop pin 276aO Thus, upon the insertion of cassette llOa as described above. cassette linking levers 284a fixed to shaft 272a are fitted into recesses 248a formed on both sides of the forward end portion of cassette llOa~ The transfer sheet lifting lever 286a moun-ted on shaft 272a is locked at a retracted position at , which its forward end ls substantially on the same plane as cassette bottom guiding portion 258a o;f receiving member 256aO
~hen, paper supplying cassette 110a is turned in a direction in which its forward end inserted in the receiving section moves upwardlyO As a result, as shown in Figure 17B, notches 253a of cassette 110a come into engagement with stop plates 270a to stop the turning of paper supplying cassette 110a by pull spring 278a &nd to prevent its rearward movementO
At the same time, with the turning of the paper supplying cassette 110a, cassette linking ]evers 284a are turned counter-clockwise, and shaft 272a is brought to the second position at which other projecting portion sections 2B2a of positioning member 274a is engaged with stop pin 276a. ~hus, lifting lever 286a is unlocked~ and by the action of spring 288a, is --elastically urged counterclockwise, whereby its forward end projects from opening 250a of cassette 110a and elastically lifts auxiliary bot-tom plate 244a and reoeptor sheet layer 246a in the cassette 110a to urge the topmost receptor sheet : elastically against paper feed roller 268aO ~wo corners o~the forward end of the top:most receptor sheet lifted by lever 286a from layer 246a come into en~agement ~ith blocking nails 252a to check its upward movementO When~in such a ~: : condition, paper feed rollers 268a are rota-ted in the : direction of arrow Es the topmost receptor sheet urged : : 25 elastically against it is delivered toward the transfer station, moved along guide portion 262a of receiving member 256a, and fed into a recep-tor sheet conveying system to be ;~: described~
When it is desired to -take out paper supplying ' ,'; , "~,'- ~ . ~ ., . ; ' . , .. . ,. ~ . ~ . :

~1~)093 cassette llOa from -the receiving sec-tion after all the receptor sheets in cassette llOa have been consumed, cassette llOa in the state shown in Flgure 17B is turned in a direction in which its forward portion moves downward to attain the state shown in Figure 17~. Conseguently, notches 253a of paper supplying cassette llOa depart from stop plates 270a, and paper supplying cassette llOa is in condition for rearward movementO ~t the same time, with the turning of the paper supplying cassette llOa, cassette linking levers 284a and Shaft 272a are turned clockwise, and shaft 272~ is returned -to the first position at which one of projecting sections 280a of positioning member 271a comes into eng~gement with stop pin 276aO ~he foremost end of paper supplying cassette llOa moving downward causes receptor s~eet-lifting lever 286a to rotate clockwise and return to its retracted position where it is locked in positionO ~hereafter, paper supplying cassette llOa is moved rearward, and taken out of the receiving sectionO
In paper supplying cassette llOa shown in the drawings, auxiliary bottom plate 244a is substantially of the same size as the receptor sheet placed on it, and only the forward end portions of auxiliary bottom plate 244a and receptor sheet layer 246a are lifted by the action of receptor sheet lifting lever 286a~ Accordingly, the receptor sheet layer 246a is inclined at a certain angleO In this case, the angle of the topm~st receptor sheet with respect to blocking nails 252a changes somewhat according to a change in the thickness of receptor sheet layer 246aO Hence, the aGtion of blocking nails 252a on the receptor sheet are -- ~
~ 93 somewhat ch~nged, qnd this mqy sometimes hamper the action of delivering only the topmost receptor sheet ex~ctlyO To cope with this situation, it is possible to utilize auxiliary bottom plate 244a which is located only beneath the front half of receptor sheet l.ayer 246~ and to provide a suitable .:
guide means on the inner surface of each of the two side wqlls of case 242a whereby auxiliary bottom plate 244a is lifted substqntially in parallel to the bottom plate of cassette llOa or llOb by the action of lifting lever 286aO According to this construction, the front half of the receptor sheet layer can be lifted substantially in parallel to the bottom plate of cassette llOa or llOb, and the angle of the topmost receptor sheet with respect to blocking nail 252a can be maintained substantially constant, ~nd therefore, the actiOn of blocking nail 252a on the receptor sheet can be maintained in the most suitable conditionO
Now, receptor sheet conveying system 112 is will be described in detail below with reference m~inly to ~igure 90 Receptor sheet conveying system 112 for conveying a receptor sheet from cassette llOa or llOb to receiving trqy 30 through the transfer station and fixing device 28 consists, for example, :
of roller pairs 2909 292~ 294 and 296 eqch consisting of a driven roller and an idle roller, a receptor sheet guide pl~te between the rolls in eqch pqir, and receptor sheet conveying roller 240 and guiae plqte 42 a].ready described above with reference to Figure 140 It is of course possible, as described in detail with reference to ~igure 5, to provide electrostatic eliminators 44 and 46 above guide plate 42 and/or above the inside end portion of receiving tray 30 - ~ ~ . . .................... . . .
., ~ ! I' ~ ,' ~ .

so as to facilitate the conveying of receptor sheetO It is important to construct -the receptoI sheet conveying system 112 such that paper jamming which occurs ~t any part of receptor sheet conveying system 112 can be rapidly and easily correctedO For this purpose, upstream of conveying system 112 for exampleg the rollers and guide plate defining the underside of the conveying system are mounte~ on supporting frame 300 pivotably fixed to pin 298 so that should pap-er-jamming occur at this part 9 support frame 300 will be turned clockwise with pin end 298 as a center to cope with tlle paper jamming rapidly ~nd easilyO Paper jamming which occurs in or near the -transfer station can be adjusted easily and rapidly by sliding in the forward direc-tion (the direction perpendicular to the sheet surface in Figure 9) support 172 having rotary drum 1089 developing device 6 and cleaning device 3~ mounted on it, as already describedO At the most upstream part and the mos-t downstream part of conveying system 112, paper jamming can be adjusted rapidly and eas1ly by first removing the paper supplying cassette llOa or llOb or receiving tray 30 through the opening which has been set free by the removing of cassette llOa or llOb or receiving tray 30 Drlvin~ s~stem ~
The driving system is now described mainly with reference to Figures 18 and 190 Referring to ~igure 18, in the preferred embodiment of the electrostatic copying appar~tus oî this invention, optical system 22, rotary drum 108, developing device 6, cleaning device 34Sfixing device 28, and receptor sheet conveying system 112 are driven by main motor DM (see ~igure 9)O

~; . ' . ' ~ ' ~ . : .

Main driving twin sprocket 304 is fixed to the output shaft of main motor DMo Arow~d one member of sprocket 304 are wrapped first endless chain 306 and second endless chain 308.
~irst endless chain 306 starts at one member of sprocket 304, ~xtends through driving sprocket 312 for driving optic~l system 22 for scanning ~which sprocket is connected selectively to driven pulley 156 (see Figure 10) of op-tical system 22 by a scanning electromagnetic clutch MCl (see Figure 20)~, sprocket 316 for returning optical system 22 twhich sprocket is connected selectively to driven pulley 156 of optical system 22 by return electromagnetic clutch MC2 (see Figure 20)~, linking sprocket 318 equipped with a linking gear, sprocket 320 for driving rotary drum 108 (which sprocket is drivingly connected to shaft 206 of rotary drum 108 as already described with reference to Figure 15, or drivingly connected to gear 344 of rotary drum 108 via a driven shaft and a gear fixed to it as described above with reference to Pigure 13A) and idle sprocket 322~ and returns to the one member of sprocket 30~0 ~econd endless chain 308 starts at the other ~ member of sprocket 304, extends through sprocket 324 fixed : to one of the shafts of a pair of press rollers for driving fixing device 28, sprocket 326 fixed to one shaft of roller pair 294 for conveying a receptor sheet, idle sprocket 328 and sprocket 330 fixed to one shaft of roller pair 296 for : 25 driving receptor shee-t conveying rollers, ~nd returns to the other member of sprocket 304O Sprocket 332 equipped with a linking gear is drivingly connected to linking sprocket 318 over which first endless chain 306 is stretched, and third endless chain 334 is wrapped around sprocket 332~ ~hird endless chain 334 starts from sprocket 332, extends through sprocket 336a selectively connected to shaft 266a of paper feed roller 268a by electromagnetic clutch CM3 (see Figure 20), sprocket 336b connected selectively to shaft 266b of paper feed roller 268b by electromagnetic clutch MC~ (see Figure 20), idle sprocket 338, sprocket 340 fixed to one shaft of roller pair 290 for driving the receptor sheet conveying rollers and sprocket 3L~2 fixed to one shaft of roller pair 292 for driving the receptor sheet conveyil~g roller, and returns to sprocket 3320 As clearly shown in Figure 19, gear 344 (see Figure 15 also) is fixed to rotary drum 1080 ~his gear 344 is drivingly connected to gear 348 fixed to the shaft of developer-holding member 50 of cleaning device 34 via speed increase gear device 346, and also to gear 354 fixed to the Shaft of developer-holding member 8 of developing device 6 via speed increase gear device 350 and idle gear 3520 A gear (not shown) is fixed to the shaft of receptor sheet conveying roller 240 disposed immediately down-stream of the transfer station, and is drivingly connected to idle sprocket 322 via an idle gearO
It will be apprecia-ted therefore that optical system 22, rotary drum 108, developing device 65 cleaning device 34 and receptor paper sheet conveying system 112 are properly driven by main ~otor DM~

~he control system is described with reference to Figures 8, 20 and 24.
Referring to Figure 8, control panel 106 disposed on the top surface of housing 100 has main switch SW, knob ~C for adjusting the amount of exposure, alarm lamp Ll for signalling 3 paper jamminga lamp IIL~ for paper supply, print button P~, preset . ., . ~ ' ,;, . : : :
.. . .

,20as3 counter PC for presetting the number of copies required, and receptor sheet selecting switch S8O
~ithin housing 100 are disposed at the positions shown in Figure 20 switch. Sl for detecting the return of first support frame 150 having first reflecting mirror 140 mounted thereon to a predetermined position, switch ~2 for detecting the movement of first support frame 150 beyond a predetermined position, switches S3 and SL~ ~Jhich cooperatively detect paper jamming7 switch ~2 for successively starting the supply of receptor sheet when many copies are made, and switches S6 and S7 for detecting the presence or absence of a receptor sheet in casse-ttes llOa and llObo Housing 100 also includes various electrical elements such as electromagnetic clutch MCl for connecting sprocket 312 to pulley 156 of op-tical system 22, electromagnetic clutch MC2 for connecting sprocket 316 to pulley 156 of optical system 22, electromagnetic clutch MC2 for connecting sprocket 316 to pulley 156 of optical system 22~ electromagnetic clutch MC3 for con-~: necting the sprocket 336a to the shaft of paper feed roller 268a, ~ electromagnetic clutch MC4 for connecting sprocket 336a to the :~ 20 shaft of paper feed roller 26Ba, electromagnetic clutch MC4 :: :
for connecting sprocket 336a to the shaft of:paper feed roller 268a, high voltage transformer HV~l for corona discharge device 20, high voltage transformer HV-2 for corona discharge device ~ 36, fan motor RM for driving suction blower 130, main motor :~ 25 DM, original illuminating lamp 128 for illuminating an original, and electrostatic eliminator lamp 320 ~: The electrical elements described hereinabove with reference to Figures æ and 20 are incorporated into the electric circuit shown in figures 21 to 24. The details of the electric circuit itself are believed to be readily , ~

understandable from ~igures 21 to 24, and a description of them is omittedO
~he operation of the preferred embodiments of the electrostatic copying apparatus of this invention is described below by main reference to Figure 8 and ~igures 20 to 240 ~ When it is desired to copy an original placed on tranSparent plate 102~ main switch SW is turned onO ~hen, as required, exposure adjusting knob EC is operated to adiust variable resistance V~ (Figure 21) to set the amount of light from lamp 128 at a suitable valueO ~urthermore, ~s required, receptor sheet select switch S8 is actuated to select a suitable size (for example, B5 or A4) of receptor sheet to be conveyed through conveying system 112.
Referring to ~igures 22 and 23, the selection of receptor sheet and the detection of receptor sheet are describedO When for example, select switch S8 (~igure 23) is actua-ted so as to select a receptor sheet (for example, of B-5 size) in cassette llOa~ the pressing of print button PB will bring electromagnetic clutch MC3 for connecting the : : 20 sprocket 336a to the shaft of paper feed roller 268a into the oper~tive state 7 as can be understood from Figure 22.
~urthermore, switch S8 1 shown in ~igure 22 interlocks with switch S8 whereby indicating lamp L2 provided within the switch S8 change-over operating member on control panel 106 is lighted to indicate the selection of receptor sheet in cassette llOaO Switch S6 for detecting the presence or absence of receptor sheet within cassette llOa lights paper supply lamp L4 when no receptor sheet is present, and subseguent pressing of print button PB does not actuate _ 91 ---.. . . .. .

relay Rl and thus does not start the copying process~ The same can be Said when select switch S8 is actuated to select ~ receptor sheet (for exa~ple, with a size ~-4) in cassette llObo Assuming that preset counter PC is set at 1 (in which case the terminal of preset counter PC is off), the control of the operation of each component part of the electrostatic copying appar~tus is summarized as follows:
(i) When first support frame 150 does not return to a predetermined position before the start of the copying process by pressing the print button PB, switch Sl is not pressed but is normally openO Hence, electromagnetic clutch MC2 is energized to return first support frame 150 to the predetermined positionO
(ii) When print button PB is pressed, relay Rl is operated and its contacts Rl 1 and R1_2 are closedO Thus, : a voltage is applied to the base of transistor Tr2 to actuate relay SSR2 and close its contact SS 2 1 ~hus, main motor DM and fan motor FM rotate and electrostatic eliminator lamp 32 is lightedO Contact Rl 1 self-maintains relay Rl~
Contact Rl 2 actuates relay R2 and relay RRl to light the original illuminating lamp 12~:and to~energize electromagnetic clutch MC3 (or MC4)~ thus starting paper supply.
(iii) When the forward end of a receptor sheet fed from paper cassette llOa (or llOb) presses switch S3 disposed on receptor sheet conveying system 112, relay R
is actuated and its contacts R3a 2 and R3~ 3 are closed-When contact R3a 1 is open, relay R2 is also open and electromagnetic clutch MC3 (or MC4) is deenergized. When ~Z~93 contact R3a 2 is closed, condenser Cl is charged, and upon completion of charging, a voltage is applied to transistor ~rl to close relay R3b and timer ~1 ~he time during which transistor ~rl is kept in operation by the charge generated in condenser Cl is determined by the time constant of a CR
circuit of condenser Cl and variable resistance VR2n Contact R3a 3 actuates high voltage transformer HV-l for corona discharge device 200 When relay R3b operates, its contact R3b 1 is opened~ and R3b 1 releases -the self-maintaining of Rl. ~urthermore, when R3b 2 is closed, SSRl is closed to actuate high voltage transformer H~-2 for corona diSCharge device 360 R3b 3 serves to per~orm changeover between electromagnetic clutch MCl and electromagnetic clutch MC2, and is connected to electromagnetic clutch MCl when it is closed~
(iv) ~imer ~1 is an on-delay timer, and after a lapse of a certain period of time that can be suitably prescribed from the time of actuation of R3a, its contact ~1 1 is closed. When ~l l is closed, magnetic clutch MCl is energized to move first support frame 150 and second support ~: frame 152 forward (scanning movement)~
Specifically, after a certain:period of time preset by timer ~l from the time when the forward end of a receptor sheet fed from cassette llO~ or llOb pressed switch S2 disposed on receptor sheet conveying system 112, first support frame 150 and second support frame 152 begin to move forward, ~: and therefore, optical system 22 begins to scan the original placed on transparent plate 102 and to project the image of the original onto the surface of rotary drum 1080 Accordingly, - 93 ~

~ 1~L;20093 by properly adjusting the time to be set by timer Tl, the forward end of the image of the original projected onto the surface of rotary drum 108 can be accurately registered with the forward end of a receptor sheet fed from paper supplying cassette 110~ (or llOb)o This registration can also be performed by a mechanical element provided a*justably on receptor sheet conveying system 112 and adapted to be operated by the forward end of receptor sheetO One example of such a mechanical element is shown in ~igure 250 In this embodiment, instead of timer ~1 and switch S3, detecting member 606 : is provided which serves to sense the forward end of receptor : sheet passing between upper guide plate 602 and lower guide plate 604 defining receptor sheet conveying system : 15 112 between roller pair 290 and roller pair 2920 ~his detecting member 606 at a part near its one end is rotatably supported by rear vertical base plate 103, and at a part near its other:end, rotatably supported by bracket 608. Bracket 608 is mounted on upper guide plate 602 adjustably in the receptor sheet conveyin~g;direction 610 by a screw which e~tends through elonga-ted sl~ot 612 extending in~the receptor sheet conveying direction 610 ~nd ls screwe= to upper guide plate 6020 One end 606a of detecting member 606 projects ~ beyond rear vertical base plate 103 and contact5 an actuator :: 25 for microswitch 6140 Other end 606b of detectin~ member 606 : : passes through opening 616 formed in upper guide plate 602, ~: extends to receptor sheet conveying system 112 between upper : guide plate 602 and lower guide plate 60L~, and further projects past opening 618 formed in lower guide plate 604.

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Detecting member 606 is rotated clockwise in ~igure 25 when the forward end of receptor sheet that is conveyed through conveying system 112 comes into engagement with other end 606b, and its one end 606a actuates microswitch 6140 When microswitch 61L~ is operated, electromagnetic clutch MCl is energized to start the forward movement of first support frame 150 and second support frame 1520 Hence, optical system 22 begins to scan the original placed on transparent plate 102 and to project the image of the original onto the : 10 surface of ro-tary drum 1080 The forward end of the image projected onto -the surface of rotary dru.m 108 and the forward end of the receptor sheet can be properly registered by changing the fixing position of bracket 608 to move detecting - ~ member 606 in the direction of ~rrow 620 wlth ~ part of detecting member 606 which is near the rear vertical base plate 103 being ~ used as a fulcrum, and thus properly adjuSting the sensing ;: : position of other end 606b of detecting member 606~ Preferably.
a plurality of protruding portions 622 are provided in the widthwise direction at spaced intervals on the top surface of bottom guide plate 60~ so as to bring the forward end of receptor sheet into exact engagement with other end 606b of detecting member 606 and to facilltate smooth conveying of the receptor sheet~ `~
(v) When the rear end of the receptor sheet moving on the receptor sheet conveying system 112 passes ~3, the ~ ~ :
pressing of $3 is released to set R3a offt and its contact R3a 1 is closed and contacts R3~ 2 and R~ 3 are opened.

When R3a 3 is off, the operation of high voltage transformer HV-l for corona discharge device 20 is stopped~ On the other : - 95 -., , . . . , , , ., - , .. ,,: . .

h~nd, condenser Cl is still charged after R3a 2 is openedO
qhus, until the charge in condenser Cl diSSipateS~ transistor ~rl operates to keep R3b in operationO
(vi) When the charge in condenser Cl is discharged 5 to a predetermined voltage level, R3b is opened, and its contact R3b-2 is openedO When R3b 2 is off, SSRl and RRl are opened to stop the operation of high voltage transformer HV-2 for corona disch~rge device 36 and light the lamp 1280 Furthermore, the connection oî R3b 3 is switched from the 10 MCl side to the MC2 side to move first support frame 150 and second support frame 152 backward (return movement) (vii) When first support frame 150 moves back-ward and presses switch Sl provided at its stopping position, switch Sl is turned off. Accordingly, electromagnetic clutch 15 MC2 is reset to stop first support frame 150 and second support frame 1520 (viii) When the rear end of the receptor sheet moving on conveying system 112 departs swi-tch S4 (Figure 24), switch S4 is turned off and ~R2-R of keep relay KR2 actuates 20 to close KR2-1 and ground the collector of transistor ~r30 I~hus, the application o:E a voltage from line X is stopped and transistor ~r3 becomes inoperatlve, Tr2, however, is stlll in the oper~3.tive st~te because of the charge on condenser C20 ~nen the charge is eliminated from condenser C2 to a 25 predetermined voltage level, ~r2 becomes inoperativeO As a result, relay SSR2 maintained in the closed st3te by~contacts Rl 1 and R3b ~ and transis-tor Tr3 is opened to stop main motor DM and fan motor FM and turn off eliminator lamp 32 ~he time during which ~r2 is maintained operative by the ,"

~'~og3 charge on condenser C2 is determined by the time constant of a CR circuit of condenser C2 and variable resistance VR30 VR3 is adjusted so that ~r2 becomes inoperative when the receptor sheet after the leaving of its rear end from switch S~ has been completely discharged onto the receiving tray.
~ en firs~ support f'rame 150 and second support frame 152 keep moving forward even after R3b is off, switch S2 for sensing the over~unning of firs-t support frame 150 is pressed by first support frame 150 and actuates KR3-L
of keep relay KR3 thereby to stop the copying processO
: ~hen prese-t counter PC is set at more than one number of copies, i-ts -terminal is turned on and so maintained until the remaining number becomes oneO When the remaining number is one~ the -terminal is turned offO When preset counter PC is on, the first support frame 150 presses switch S5 during its backward movement (return movement) to turn on switch S5 and thereby actuate relay R2O Consequently, its contact R2 1 is closed to energize electromagnetic clutch MC3 (or MC4) and to start paper supply~O When the forward end of receptor sheet supplied from cassette llOa or llOb presses switch ~3, relay R3a is actuated and its contact R3a 1 is opened, Furthermore, relay R2~ lS opened to deenergize the electromagnetic clutch MG3 (or MC4)o .Als:o, R3a_2 and R3a 3 are closedO When R~a 2 is on~ charge is generated on condenser C1 and transistor ~rl is actuatedO R3b is also closed and its contact R3b 2 is ^losedO ~hus, relay RRl is actuated to light original-illuminating lamp 1280 Sensing of paper jamming a-t receptor sheet conveying system 112 is described with particular reference to Figure 2~o ~ he basic theory of sensing p~per jamming is that the tlme tc from the sensing of the rear end of receptor sheet by switch S3 to the sensing of the rear end of the 5ame receptor sheet by switch SL~ ~nd the time tt preset by on-delay timer ~2 are set in a relation tc <tt, and the operation of the apparatus is stopped and alarm lamp L
is lighted when paper j.~mming causes -the relation tc~tt~
: When the forward end of the receptor sheet presses switch S3, relay 3a actuates to close its contact X3~ L~ As a result, transistor ~r5 becomes operative, and condenser C3 is chargedO Eowevsr~ KR2-L does not operate since the high ~ voltage side of KR2~ is simultaneously off. When the rear ; end of the receptor sheet has passed switch S3, the pressing of S3 is releas.ed to open R3~ 4 cand set the hlgh voltage ~:: 15 side in operationO Since transistor ~r5 is operative .for ~:
a certain period of time because of the charge on condenser ; C3, KR2-L operates and:its contact KR2-1 is closed thereby : to actuate timer ~2 (when there is an input into timer ~2~
ts contact ~2 1 is olosed after a press-t time,~and when the 20 input is cut off before the preset time elapses7 timer ~2 -~ returns to the original state)O When receptor sheet is conveyed in normal conditlon, switch S4 senses ths re~r end ~: : of the receptor shee-t before the expiration of the time preset by timer ~2 to actuate KRZ-Ro ..~ccordingly, contact ~:
25 KR2 1 is opened to stop tne operation of timer ~2 ~en KR2-R does not actuate~, contact ~2 1 of timer T2 is closed after the presst time -to actuate KR2--L and open its contact ; KR3 1 Accordin~ly, ths actuation of relay SSR2 stops and the operation of the apparatus stopsO ~t the same time, Qg3 alarm lamp ~1 is lighted. The keep relays KR2 and KR~ operate by one pulse and self maintain mechanically, and even when the power supply is cu-t off, the self-maintaining condition remainsh The self-maintaining condition may be released by applying a signal to another input terminal (reset coil)O
In resuming the operation of the apparatus after proper correction of paper jamming, it is necessary to operate reset switch RS which is provided for releasing the self-maintaining condition of the relaysO

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Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An electrostatic copying process which comprises (1) a step of forming an electrostatic latent image on the surface of a photosensitive member having a photoconductive layer, (2) a step of developing the electro-static latent image by applying a fine powdery developer to the electro-static latent image to form a toner image on the surface of the photosensitive member, (3) a step of transferring the toner image by conveying a receptor sheet to a transfer station and successively contacting the surface of the photosensitive member closely with the surface of the receptor sheet in the transfer station to transfer the toner image to the surface of the receptor sheet, (4) a step of fixing the toner image by separating the receptor sheet from the surface of the photosensitive member and fixing the toner image transferred onto the surface of the receptor sheet, (5) a step of eliminating electrostatic charge by irradiating the surface of the photosensitive member with an electrostatic eliminating lamp after the toner image has been trans-ferred to the receptor sheet, and (6) a step of cleaning the surface of the photosensitive member by removing the developer remaining on the surface of the photosensitive member after the electrostatic eliminating step, wherein the cleaning step (6) is carried out by magnetically holding the same developer as used in the developing step on the surface of a developer-holding member by means of a magnet disposed within the developer-holding member, moving the surface of the developer-holding member in a direction opposite to the moving direction of the surface of the photosensitive member to contact the two surfaces at reasonable relative speeds through the layer of the developer, and thus mechanically brushing the surface of the photo-sensitive member by the layer of the developer.

2. The process of claim 1 wherein the developer magnetically held on the surface of the developer-holding member for the cleaning step is a mono-component developer composed of a conductive or semiconductive magnetic fine powder.

3. The process of claim 2 wherein the developer-holding member for the cleaning step is a rotatable hollow cylindrical sleeve having an in-sulating surface coating.

4. The process of claim 3 wherein the magnet disposed within the developer-holding member for the cleaning step is a roll-like permanent magnet having a plurality of magnetic poles, and one of the magnetic poles which is located most closely to a position at which the surface of the developer-holding member is closest to the surface of the photosensitive member is downstream in the rotating direction of the developer-holding mem-ber by a certain angle with respect to the position at which the two surfaces are closest to each other.

5. The process of any one of claims 1 to 3 wherein the thickness of the developer layer held on the surface of the developer-holding member is controlled by a brush length adjusting member whose forward end approximates the surface of the developer-holding member at a position downstream of an area in which the surface of the developer-holding member is contacted with the surface of the photosensitive member through the developer layer in the moving direction of the surface of the developer-holding member; and the distance d5 between the forward end of the brush length adjusting member and the surface of the developer-holding member is adjusted to 0.6-0.25 mm, and the distance d4 between the surface of the electrostatic latent image-bearing member and the surface of the developer-holding member at a position at which both are closest to each other is adjusted to 1.2-0.5 mm.

6. The process of claim 4 wherein the thickness of the developer layer held on the surface of the developer-holding member is controlled by a brush length adjusting member whose forward end approximates the surface of the developer-holding member at a position downstream of an area in which the surface of the developer-holding member is contacted with the surface of the photosensitive member through the developer layer in the moving direction of the surface of the developer-holding member; and the distance d5 between the forward end of the brush length adjusting member and the surface of the developer-holding member is adjusted to 0.6-0.25 mm, and the distance d4 between the surface of the electrostatic latent image-bearing member and the surface of the developer-holding member at a position at which both are closest to each other is adjusted to 1.2-0.5 mm.