JPH0219926B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus that can be applied to, for example, a two-color color copying machine.

[Technical background of the invention and its problems]

2. Description of the Related Art In recent years, color image forming apparatuses such as copying machines have become increasingly popular, and two-color copying machines that can produce images in colors other than black have been put into practical use.

However, in conventional two-color color copying machines, etc., multiple cartridges that integrate a developing device and a photoreceptor are prepared and selectively replaced, which is said to be extremely troublesome to operate. There was a problem.

[Purpose of the invention]

The present invention was made based on the above circumstances, and
The object is to provide an image forming apparatus which can perform black or color development extremely easily, and can also easily perform color exchange in color development.

[Summary of the invention]

In order to achieve such an object, the present invention allows a black developing means and a color developing means to be installed simultaneously in the apparatus main body, and the black developing means or the color developing means installed in the apparatus main body can be selected. The image forming apparatus is configured to form an image by operating the color developing means removably on the apparatus main body, and the color developing means inside the apparatus main body and the color developing means outside the apparatus main body are connected to each other. The color developing means can be replaced.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows 2 as an image forming apparatus of the present invention.
The configuration of a color copying machine is shown. In the figure, 1 is a copying machine main body. On the top surface of this copying machine main body 1, a document table 2 that can freely move back and forth in the left and right direction (direction of arrow a) is provided. An operation panel (not shown) is provided on the front edge, on which a display, a numeric keypad, a color selection button, an exposure setting volume, a print key, etc. are arranged.

Further, a paper feed cassette 3 is attached to the right side of the apparatus main body 1, and a paper discharge tray 4 is attached to the left side. The cassette cover 5 of the paper feed cassette 3 serves as a manual feeding table 6 for manually feeding paper P' as appropriate.

A track-shaped photoreceptor 7 is arranged approximately in the center of the main body 1 of the copying machine. A charging device 8, an optical device 9, a two-color developing device 10 (described later), a transfer device 11, a peeling device 12, a cleaning device 13, and an afterimage erasing device 14 are arranged in this order around the photoreceptor 7.

In addition, a paper feed cassette 3 is located at the bottom of the copying machine main body 1.
The paper P that is automatically taken out via the paper feed roller 15 or the paper P' that is manually fed from the manual feed tray 6 is transferred to the paper output tray via the image transfer section 16 between the photoreceptor 7 and the transfer device 11. A paper conveyance path 17 leading to 4 is formed. A pair of aligning rollers 18 and 18 are arranged on the upstream side of the image transfer section 16 of the paper conveyance path 17, and a fixing device 19 and a pair of paper discharge rollers 20 and 20 are arranged on the downstream side.

Further, the optical device 9 has a reflector 21 on its back.
It has a structure including an exposure lamp 22 and a lens mirror system 23 surrounded by. Photoreceptor 7
is driven by a drive mechanism (not shown) in the direction of arrow b in synchronization with document table 2. First, a document image uniformly charged by the charging device 8 and uniformly irradiated by the exposure lamp 22 is imaged on the photoreceptor 7 by the lens mirror system 23 to form an electrostatic latent image. . The formed electrostatic latent image is turned into a developer image by the developing device 10 and sent to the transfer device 11 side.

Automatically or manually fed paper P or P' is fed by a pair of aligning rollers 18, 18, and the developer image previously formed on the photoreceptor 7 is transferred onto the paper P or P' by the transfer device 11. do. Furthermore, a peeling device 12 using AC corona discharge
The developer image is peeled off from the photoconductor 7 and passed through the conveyance path 17, and the developer image is transferred to the paper P by the fixing device 19.
The sheet is fused and fixed on P' and is discharged onto a removable tray 4 by a pair of paper discharge rollers 20, 20.

On the other hand, residual toner remaining on the photoconductor 7 after the developer images are transferred onto the sheets P and P' is cleaned by a cleaning device 13, and the potential on the photoconductor 7 is reduced to below a certain level by an afterimage erasing device 14. Make the next copy operation possible.

Further, a fan as a cooling device is provided inside the apparatus main body 1, and exhausts heat generated from a heat generating section inside the apparatus, an exposure lamp 22, and a fixing device 19. 24 is a power switch, 25 is a door switch, and an exhaust device 28 is also attached to the main motor 27 to cool down the heat generated by the power source 26 and the like.

Inside the copying machine main body 1, an upper frame and a lower frame (not shown) are pivotally supported at one end via a support shaft (not shown), and the other ends of both frames can be opened at a desired angle, for example, 30°. It is configured as follows. A charging device 8, a lens mirror system 23, an exposure lamp 22, a developing device 10, a cleaning device 13, an afterimage erasing device 14, and other devices are attached to the upper frame by appropriate means around the photoreceptor 7, Further, a fan as a cooling device, a paper feed roller 15 of a paper feed device, and a document table 2 are also attached to the upper frame to constitute an upper unit 1A. Also, the lower frame has a paper feed cassette 3 and a transfer device 1.
1. Peeling device 12, conveyance path forming guide plate 30,
Each mechanism such as the fixing device 19, the pair of paper ejection rollers 20, 20, the tray 4, the main motor 27, the power supply section 26, etc. are attached by appropriate means to constitute the lower unit 1B. After rotating and removing the front cover of the copying machine main body 1, the sheets P and P' are almost conveyed through the transport path 1 through a housing opening/closing device (not shown).
It is constructed so that it can be opened and closed along the lines 7. Therefore, even when sheets P and P' become jammed on the conveyance path 17, they can be easily taken out.

Note that 18 and 18 indicate paper P that is automatically fed from the paper feed cassette 3 or paper that is manually fed.
In addition to correcting the inclination of the leading end surface of P', the paper P is
Alternatively, it is a pair of aligning rollers that supplies P' toward the transfer device 11, and 31 is a manual feed detection switch disposed just before the pair of aligning rollers 18, 18.

32 is a paper discharge switch, and 34 is a paper empty switch that detects when the paper P in the paper feed cassette 3 is empty.

Further, 35 is a high voltage transformer, 36 is a static elimination brush, and 38 is an auxiliary reflector.

Further, 39 is a blade solenoid that brings the cleaning blade 40 of the cleaning device into and out of contact with the photoreceptor 7 .

As shown in detail in FIG. 2, the developing device 10 has a developing roller 50 as a first developing member and a developing roller 51 as a second developing member, and these developing rollers 50 and 51 are selectively driven. By doing so, it is possible to obtain color copies of black or one other color such as red, yellow, blue, or green.

The developing device 10 includes a first developing unit 52 as a color developing means including a first developing roller 50 and a second developing unit 53 as a black developing means including a second developing roller 51. The second developing unit 53 in the lower stage is fixedly provided to the copying machine main body 1, and the first developing unit 52 in the upper stage is formed in the shape of a cartridge and can be pulled out upward in the figure. There is. and,
The frequently used black developer (black toner) is used in the second developing unit 53 in the lower stage, and the color developer (color toner) is used in the first developing unit 52 in the upper stage.

Further, a cartridge type first developing unit 5
2 consists of a developing mechanism section 54 and a developer replenishing section 55, and the developing mechanism section 54 has a developing roller 50 and a developer magnetic brush 56 formed on the surface of the developing roller 50 in sliding contact with the photoreceptor 7. That is, a doctor 58 that is provided upstream of the development position 57 and regulates the thickness of the developer magnetic brush 56;
a scraper 60 provided on the downstream side of the developer roller 7 and scraping off the developer magnetic brush 56 on the surface of the developing roller 50 and guiding it to the developer storage section 59; and a developer stirring body 61 accommodated in the developer storage section 59. is housed in a casing 62. In addition,
A developer concentration detector 63 is attached to the casing 62 at a position above the developing roller 50 to detect the developer concentration by magnetically detecting changes in the magnetic permeability of the developer 56a.

Further, the developing roller 50 is provided with a magnetic field so that its center is located on a straight line _L2 drawn through the center of rotation of the photoreceptor 7 and at an angle α (α=51°) with respect to the horizontal line _L1 . It is composed of a roll 64 and a sleeve 65 that is fitted onto the magnetic roll 64 and rotates clockwise in the figure.

Further, the magnetic roll 64 has five magnetic pole parts 66a to 66a.
66e, the first, third, and fifth magnetic pole portions 66
a, 66c, and 66e are N poles, and the second and fourth magnetic pole portions 66b, 66d are S poles, and the angle θ ₁ between the first magnetic pole portion 66a and the second magnetic pole portion 66b is θ. ₁ = 50°, the angle θ 2 between the second magnetic pole portion 66b and the third magnetic pole portion 66c is θ ₂ =71°, and the angle θ ₂ between the third magnetic pole portion 66c and the fourth magnetic pole portion 66d is Angle θ ₃ is θ ₃
=60°, fourth magnetic pole part 66d and fifth magnetic pole part 66
The angle θ ₄ with respect to e is set to θ ₄ =60°.

Further, the developer replenishing section 55 has a developer replenishing port 67 provided in a hopper 68 facing the developer storage section 59 of the developing mechanism section 54 and in a state in which the developer replenishing port 67 is closed within the hopper 68. developer replenishment roller 69 and this developer replenishment roller 69
A pair of stirring rollers 7 stir the developer 56a in the hopper 68 so as to convey the developer 56a to the side.
0.70.

Further, the second developing unit 53 has almost the same basic configuration as the first developing unit 52 described above, and the shape of the hopper 68' of the developer replenishing section 55' and the magnetic pole of the magnetic roll 64' of the developing roller 51 are different. The differences include the arrangement structure of the developer concentration sensor 63', the mounting position of the developer concentration sensor 63', and the addition of a second scraper 80 which is narrow (about 50 mm) and has an inclination of about 20 degrees. Other identical components are given the same reference numerals with a dot and detailed explanation will be omitted.

The magnetic roll 64' of the developing roller 51 has four magnetic pole parts 66'a to 66'd, the first and third magnetic pole parts 66'a and 66'c are N poles, and the second and fourth magnetic pole parts are The magnetic pole parts 66'b and 66'd are S poles, and the first
The angle θ ₅ between the magnetic pole part 66'a and the second magnetic pole part 66'b is θ ₅ =78°, and the angle θ 5 between the second magnetic pole part 66'b and the third magnetic pole part 66'b is
The angle θ ₆ between the third magnetic pole portion 66′c and the fourth magnetic pole portion 66′c is θ ₆ =70°, and the angle θ ₇ between the third magnetic pole portion 66′c and the fourth magnetic pole portion 66′d is θ ₇ =80°. Each is set to ゜.
Further, this magnetic roll 64' is provided so that its center is located on a straight line _L3 that passes through the rotation center of the photoreceptor 7 and forms an angle β (β=1°) with respect to the horizontal line _L1 . There is.

On the other hand, the magnetic rolls 64 and 6 of the first developing unit 52 and the second developing unit 53
4' is configured to be able to be rotated to a state where the rotation angle is approximately 25 degrees, and as a result of this rotational displacement, developer magnetic brushes 56, 56' are applied to the surfaces of the developing rollers 50, 51. can be formed or removed.

Then, by switching the magnetic rolls 64, 64' of the first developing unit 52 and the second developing unit 53 to predetermined positions by a magnetic roll driving means, which will be described later, the first developing unit 52 or the second developing unit Developer magnetic brushes 56, 56' are formed only on the surface of one of the developing rollers 64, 64' of 53.

That is, when operating the first developing unit 52 side, as shown in FIG.
c is opposed to the developing position 57, and the doctor 58 is positioned approximately midway between the first magnetic pole 66a and the second magnetic pole 66b, and the magnetic roll 64' on the second developing unit 53 side is moved to the first magnetic pole 6
6'a faces the doctor 58'. The developing roller 64 on the first developing unit 52 side
A developer magnetic brush 56 is formed only on the surface.

In addition, when operating the second developing unit 53 side, as shown in FIG. 3, the magnetic roll 64 on the first developing unit 52 side is rotated approximately 25 degrees clockwise from the position shown in FIG. The first magnetic pole 66
a to face the doctor 58, and rotate the magnetic roll 64' on the second developing unit 53 side by about 25 degrees counterclockwise from the position shown in FIG.
The doctor 58' is positioned approximately midway between the second magnetic pole 66'a and the second magnetic pole 66'b. and,
A developer magnetic brush 56' is formed only on the surface of the developing roller 64' on the second developing unit 53 side.

the first magnetic pole 66a of the magnetic rolls 64, 64';
66'a is a doctor 58,5 made of non-magnetic material.
The reason why the developer magnetic brushes 56, 56' are not formed on the surfaces of the developing rollers 50, 51 when facing the developing rollers 8' is that the magnetic flux density of the magnetic brushes is in a state of flux at the magnetic poles 66a, 66'a. agent 56
Since the adsorption force for a and 56'a is weak, the doctor
8, 58', and even if the sleeves 65, 65' rotate, the developer 56a, 5
6'a does not pass through the doctor portions 58, 58'.

Driving force is transmitted to each driving portion of the first developing unit 52, that is, the sleeve 65 of the developing roller 50, the developer stirring body 61, and the developer replenishing roller 69 via a first driving force transmission system 85, which will be described later. It is becoming more and more like this. Further, driving force is transmitted to each driving portion of the second developing unit 53, that is, the sleeve 65' of the developing roller 51 and the developer stirring body 61' via a second driving force transmission system 86, which will be described later. It's getting old.

The first and second driving force transmission systems 85 and 86 are constructed as shown in FIGS. 4 to 6, and include a reversible motor 87 as a common driving source.
By rotating forward or backward, the first and second
The driving section of either one of the developing units 52 and 53 is selectively operated. The mechanism is simplified, the number of parts is reduced, and early deterioration of the developers 56a and 56'b due to unnecessary stirring and transportation can be prevented.

The driving force transmission system will be described below with reference to FIGS. 4 to 6. FIG. 4 is a schematic front view showing the first and second driving force transmission systems 85 and 86, and FIG. 5 is a schematic front view showing the first and second driving force transmission systems 85 and 86.
6 is a cross-sectional view showing a state in which FIG. 6 is expanded around a drive gear 88. FIG. The first driving force transmission system 85 includes an intermediate gear 89 that meshes with the driving gear 88, a first driven gear 90 that meshes with the intermediate gear 89, and a first driven gear 90 that meshes with the intermediate gear 89.
The second driven gear 92 has an intermediate gear 91 that meshes with a driven gear 90, and a second driven gear 92 that meshes with this intermediate gear 91.

Further, the second drive system transmission system 86 includes a third driven gear 93 that meshes with the drive gear 88, an intermediate gear 94 that meshes with this driven gear 93, and a fourth driven gear that meshes with this intermediate gear 94. 95.

When the drive gear 88 rotates normally, that is, in the direction of the solid line arrow A in FIG. Gear groups 93, 94,
95 respectively rotate in the direction of the solid line arrow, and the drive gear 88 rotates in reverse, that is, in the direction of the broken line arrow B, each gear group 89,
90, 91, 92 and second driving force transmission system 86
Each gear group 93, 94, 95 rotates in the direction of the dashed arrow.

Further, the first driven gear 90 is a drive shaft 65a that is integral with the sleeve 65 of the first developing roller 50.
The second driven gears 92 are respectively attached to the drive shafts 61a of the developer stirring body 61 via one-way clutches 97, and the second driven gears 92 are attached to the respective drive shafts 65a, 61a through one-way clutches 97.
A is configured so that the driving force is transmitted only when the gears 90 and 92 rotate in the directions shown by the solid line arrows, that is, when the drive gear 88 rotates normally, and the gears rotate in the direction shown by the dashed-dotted line arrow.

Further, the third driven gear 93 is connected to the drive shaft 65'a which is integral with the sleeve 65' of the second developing roller 51.
The fourth driven gear 95 is attached to the drive shaft 61'a of the developer agitator 61' via a one-way clutch 97, and
1'a, the driving force is transmitted only when the gears 93 and 95 rotate in the directions shown by the dashed arrows, that is, when the driving gear 88 rotates in reverse, and the gears rotate in the directions shown by the dashed-dotted arrows.

The drive gear 88 is rotatably supported via bearings 98 as shown in FIG.
It is attached to a rotating shaft 110 that interlocks with the drive shaft 87a of No. 7. That is, a gear 111 is attached to the rotating shaft 110, and this gear 111 is attached to a bearing 11 on a support shaft 114 installed between a motor mounting frame 112 and a stay 113 integrated therewith.
It meshes with a gear 116 rotatably mounted via gears 5 and 115. A gear 117 having a larger diameter is integrally formed on the gear 116, and this gear 117 is connected to the drive shaft 87a of the reversible motor 87.
The gear 118 is in mesh with the gear 118 attached to the gear 118.
Therefore, the drive shaft 87a of the reversible motor 87
The forward and reverse rotation of the gears 118, 117, 11
6, 111 to the rotating shaft 110, so that the first and second developing units 52, 53 can be selectively operated simply by switching the reversible motor 87 between forward and reverse rotation. It's getting old.

Note that switching between forward and reverse rotation of the reversible motor 87 is performed by pressing a color designation button on an operation panel (not shown).
The first magnetic pole 66a, 66'a of the inactive magnetic roll 64, 64' is switched to face the doctor 58, 58'.

Further, an intermediate gear 89 that meshes with the drive gear 88 and the first driven gear 90 is rotatably attached to a support shaft 121 via a bearing 120. The support shaft 121 is attached to an arm 123 that can swing around a housing 122 that holds the bearings 98, 98 that pivotally support the rotating shaft 110, and is securely connected to the drive gear 88 and the first driven gear 90. Its position can be changed so that it can mesh with the

Further, the first stirring roller 70 of the first developing unit 52 is connected to the first operating mechanism 12 shown in FIG.
The second stirring roller 70 and the developer replenishing roller 69 are driven intermittently through the stirring roller 4, and the second stirring roller 70 and the developer replenishing roller 69 are simultaneously driven in conjunction with the movement of the stirring roller 70.

That is, the first developing unit 52
A ratchet gear 125 is attached to one end of the shaft 70a of the stirring roller 70, and this ratchet gear 125 is connected to a ratchet pawl 128 attached to an operating arm 127 that rotates in conjunction with the ON/OFF operation of a solenoid 126. It is designed to be driven intermittently by a predetermined amount via the .

In addition, sprockets (not shown) are fitted to the shafts 70a, 70b of the first and second stirring rollers 70, 70 and the shaft 69a of the developer replenishing roller 69, respectively, and an endless chain (not shown) is fitted around them. The stirring rollers 70, 70 and the developer replenishing roller 69 are integrally driven via this driving force transmission system (not shown).

Further, the stirring roller 70' and the developer replenishing roller 69 of the second developing unit 53 are connected to a second operating mechanism 124' having the same configuration as the first operating mechanism 124 and a driving force transmission system having substantially the same configuration. It is designed to be driven intermittently at the same time via the
Note that the same components as the first actuation mechanism 124 are given the same reference numerals with a dot, and detailed description thereof will be omitted.

Next, the configuration of the magnetic roll driving means 100, 100' for rotationally displacing the magnetic rolls 64, 64' to form or remove developer brushes 56, 56' on the surfaces of the developing rollers 50, 51 will be explained. This will be explained with reference to FIGS. 7 to 9 a and b. Shafts 64a, 6 of the magnetic rolls 64, 64'
One end of 4'a is pivotally supported via a bearing 131 attached to a frame 130, and a lever 132 is attached to the tip. This lever 1
The tip of the arm 32 is engaged with an engagement groove 134a of an arm 134 rotatably mounted via a support shaft 133. Furthermore, a first support part 134b formed at the lower part of the pivot end side of the arm 134 is connected to a plunger 135a of the solenoid 135, and a second support part 134b formed at the upper part of the pivot end side of the arm 134 is connected to the plunger 135a of the solenoid 135.
One end of a tension spring 136 is connected to 4c.

When the solenoid 135 is in the OFF state, the arm 134 is moved to the position shown by the two-dot chain line in FIG. 6
The lever 132 is held in a position where the lever 6'a faces the doctors 58, 58'. Therefore, when the solenoid 135 is OFF, developer brushes 56 and 5 are on the surfaces of the developing rollers 50 and 51.
6' is not formed.

Further, when the solenoid 135 is in the ON state, the arm 134 resists the biasing force of the tension spring 136 and moves to the position shown by the solid line in FIG.
As shown in Figure B, the first magnetic pole parts 66a, 66'a
The lever 132 is rotated to a position where it faces the doctors 58, 58'. Therefore, when the solenoid 135 is turned on, developer brushes 56 and 5 are placed on the surfaces of the developing rollers 50 and 51.
6' is formed.

The above-mentioned doctor 58' is also shown in FIGS. 2 and 3.
As shown in the figure, the doctor body 5 is made of non-magnetic material.
8'a, and a first magnetic body 5 made of a band-shaped iron plate provided along the longitudinal direction of this doctor body 58'a.
8'b, and second magnetic bodies 58'c and 58'c made of iron plates provided at both ends of the doctor body 58'a.
(only one is shown).
The first and second magnetic bodies 58'b, 5
8'c and 58'c are the first magnetic pole parts 66'a when the first magnetic pole parts 66'a face the doctor 58' and remove the developer 56'a from the surface of the developing roller 51.
The structure is such that lines of magnetic force are formed between the developer 56'a and the developer 56'a to more reliably prevent the developer 56'a from being taken out.

The doctor 58 includes a doctor body 58a made of a non-magnetic material, and magnetic bodies 58c and 58 made of iron plates provided at both ends of the doctor body 58a.
c (only one side is shown),
The developer 5 is removed in the same manner as in the case of the doctor 58' described above.
6a is prevented from being taken out. This doctor 58 is not provided with a magnetic body along the longitudinal direction of the doctor main body 58a like the doctor 58' described above, and the developing roller 58 facing the doctor 58 is
The magnetic lines of force formed between the first magnetic pole part 66a of the developing roller 51 and the fourth magnetic pole part 66'd of the developing roller 51 are used to prevent the developer 56a from being taken out.

Further, a magnetic plate 14 is provided between the developing roller 50 and the developing roller 51 as shown in FIGS. 2 and 3.
0 is provided, and the other magnetic roll 64, 6
The influence of the magnetic flux density pole distribution of 4' is weakened, and a good developer conveyance operation can be performed.

Note that 141 shown in FIGS. 2 and 3 is the second
This is a developer empty detection means for detecting that the amount of developer 56'a in the developer hopper 68' of the developing unit 53 has decreased, and is integrated with a detection lever 142 that rotates according to the amount of developer. A magnet 144 attached to the actuator 143 of the hopper 6
It is configured to operate by being close to a reed switch 145 as a detector provided outside of the sensor 8'.

Further, as shown in FIGS. 2, 3, and 10, a cover 150 that constitutes a part of the upper surface of the apparatus main body 1 is provided on the upper surface side of the two-color developing device 10 so as to be openable and closable. When 150 is opened, the lid 152 opens and closes the top opening 151 for replenishing the developer of the first developing unit 52 and the top opening 15 for replenishing the developer of the second developing unit 53.
A lid body 152' that opens and closes 1' is exposed. By opening these lids 152, 152', the developer 56a, 56'a can be easily replenished from the top side.

Further, these lids 152, 152' are provided with color display sections 153, 153', so that the colors of the developers 56'a, 56'a stored inside can be easily distinguished, and the colors of different colors can be easily distinguished. This prevents developer from being mixed in accidentally.

On the other hand, the first developing unit 52 containing the color developer 56a is of a cartridge type that can be attached to and detached from the apparatus main body 1, and can be pulled up with the handle 155 (see FIG. 10) in an upright position. It is designed so that it can be easily removed and replaced with a developing unit (not shown) containing developer of another color.

That is, positioning members 156,
156 (only one shown) is attached to these positioning members 156, 156, and support shafts 157, 1
57 to both end support rod portions 15 of the handle 155.
5a and 155a are rotatably pivoted.

Support rod portions 155a, 155a of the handle 155
As shown in FIGS. 11 and 12, each has a hook 15 that is rotatable around a support shaft 157.
8 is integrally attached, and is configured to engage with a locking pin 159 provided on the device main body 1 side to restrict upward movement. An engagement groove 156a serving as a first positioning part and an end surface 156b serving as a second positioning part formed on the lower end side of the positioning member 156 engage with positioning pins 160 and 161 provided on the apparatus main body 1 side. The first developing unit 52 is adapted to come into contact with the first developing unit 52.
It has a structure that allows it to be held in a predetermined position. Furthermore, when the handle 155 is raised up, the engagement between the hook 158 and the locking pin 159 is released, as shown in FIG.
As shown in Figure B, the hook 158 is attached to the locking pin 159.
By further pushing in from the horizontal position, the hook 158 and the locking pin 159 are securely engaged to press the developing unit 52 downward, as shown in FIG. 12C. ing.

Therefore, if the handle 155 is in an upright state, the first developing unit 52 can be attached and detached, and after the first developing unit 52 is inserted, the handle 15
5, the first developing unit 52 can be fixed, making its operation extremely easy.

Further, the capacity of the hopper 68' of the second developing unit 53 containing the frequently used black developer 56'a is set larger than the capacity of the hopper 68 of the first developing unit 52 containing the color developer 56a. This allows for longer developer replenishment intervals and easier maintenance.

Next, the developing operation of the developing device 10 will be explained. First, when the first developing unit 52 side is designated to be operated by the color designation button, the magnetic rolls 64, 64' enter the state shown in FIG. The sleeve 65 of the developing roller 50 rotates clockwise in the state shown in FIG. 2, forming a developer magnetic brush 56 on the surface of the sleeve 65.

Then, the electrostatic latent image previously formed on the photoreceptor 7 is developed with the color developer 56a.

When the development of the electrostatic latent image is completed in this way, the first magnetic roll 64 is rotated by about 25 degrees, and the first magnetic pole 66a faces the doctor 58, so that the developer magnetically flows onto the sleeve 65. brush 56
New formation of the developer magnetic brush 56 is stopped, and in this state, the sleeve 65 is further rotated by a predetermined amount to remove the developer magnetic brush 56.
is removed. Note that at this time, the developer magnetic brush 56' is not formed on the second developing roller 51 either, and next, either of the developing units 52, 53
Even if specified, problems such as color mixing will not occur.

In addition, a second developing unit 5 is used to develop the black color.
If 3 is specified, magnetic rolls 64, 64'
reaches the state shown in FIG. 3, the reversible motor 87 rotates in reverse, and the sleeve 65' of the second developing roller 51 rotates clockwise in the state shown in FIG. brush 5
6' is formed. After the electrostatic latent image on the photoreceptor 7 is developed to black in the same manner as described above, the developing operation is completed with the developer magnetic brush 56' removed from the surface of the sleeve 65'.

On the other hand, the developing unit 52 in the developing operation state,
The developer stirring bodies 61, 61' and the stirring mechanisms 70, 70' of 53 are always in operation, and the developer supply rollers 69, 69' are connected to the developer concentration detectors 63, 63'.
Developers 56a and 5 are released as appropriate according to the signal from 63'.
The replenishment operation 6'a is performed to maintain a good developing operation.

Note that the magnetic roll 6 of the first and second developing rollers
By setting the magnetic pole arrangement structure of magnetic poles 4 and 64' as described above, the formation condition of developer magnetic brushes 56 and 56' is not impaired.

Also, a first development unit 52 for color development
Since the developer is provided in the upper stage of the second developing unit 53 for black development, even if the developer spills from the upper stage for some reason, since it is the color developer 65a, it will not be noticeable due to the black development in the second developing unit 53, and the image will be There is no significant loss in quality.

〔Effect of the invention〕

As explained above, the present invention allows the black developing means and the color developing means to be installed simultaneously in the apparatus main body, and selectively selects the black developing means or the color developing means installed in the apparatus main body. The image forming apparatus operates to form an image, and the color developing means is detachably supported on the apparatus main body, and the color developing means inside the apparatus main body is connected to the color developing means outside the apparatus main body for other colors. Since the developing means for use in the present invention is made replaceable, black or color development can be carried out very easily, and the color development can also be easily changed.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a schematic configuration diagram of a copying machine as an image forming apparatus of the present invention, FIG. 2 is a schematic longitudinal sectional front view of a developing device, which is a main part; Fig. 3 is a schematic longitudinal sectional front view showing different operating states of the main parts, Figs. 4 to 6 show the configuration of the driving force transmission system, and Fig. 4 is a front view showing the meshing state of the gear group. 5 is a cross-sectional view showing the developed state, FIG. 6 is a cross-sectional view showing the driving force transmission state to the driving gear, FIG. 7 is a partially sectional plan view showing the magnetic roll drive means, and FIG. 9A and 9B are explanatory diagrams similarly showing the operating state, and FIG. 10 is a schematic perspective view of the developing device section.
FIG. 1 is a front view showing the fixing structure of the developing unit, and FIGS. 12A, 12B, and 12C are explanatory views showing the engagement and disengagement relationship between the handle and the hook. DESCRIPTION OF SYMBOLS 1... Copying machine main body (apparatus main body), 10... Two-color color developing device, 52... First developing unit (color developing means), 53... Second developing unit (black developing means), 58, 58'...Doctor,
56a, 56'a...Developer.

Claims (1)

[Claims] 1. An image in which a black developing means and a color developing means can be installed simultaneously in the apparatus main body, and an image is formed by selectively operating the black developing means or the color developing means installed in the apparatus main body. The forming apparatus is such that the color developing means is detachably supported on the apparatus main body, and the color developing means inside the apparatus main body can be replaced with the color developing means for other colors outside the apparatus main body. An image forming apparatus characterized by: