JP4354757B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a printer, a copier, or a facsimile machine provided with a cleaning device as one of electrophotographic processes.

  In general, in an image forming apparatus using this type of electrophotographic process, an electrostatic latent image is formed on a photosensitive member by performing a charging step and an image writing step on the photosensitive member forming an image carrier. The electrostatic latent image is subjected to visible image processing using toner in the development process. The toner image subjected to the visible image processing with toner is electrostatically transferred to a recording medium such as transfer paper by a transfer process, and the transferred toner is fixed in a fixing process to be a copy.

  Here, in the transfer process, the toner image transferred from the photosensitive member to the transfer paper does not transfer all of the transferred toner to the transfer paper, and a part of the toner image may remain on the photosensitive member. .

  Prior to the formation of a new latent image, the transferred photoconductor is included in toner, paper powder, rosin, Mg, Al, and K, Na, or other transfer paper adhered to the photoconductor surface together with the remaining charge. It is used for the cleaning process which removes the additive which has been carried out. These additives are not those for transfer paper, but also satisfy various properties required for toners such as charging properties, fixing properties, and fluidity in addition to the resin component that is the base material of toners. In addition to toner and paper powder, these additives also adhere to the photoreceptor surface.

  Conventionally, it is known that a cleaning blade is provided in pressure contact with the surface of the photoconductor in the cleaning process, and the residue is removed by grinding the photoconductor surface with the cleaning blade, so-called polishing. Is also known.

  Foreign particles such as toner lump and paper dust adhere to and accumulate on the edge of the cleaning blade that is in contact with the photosensitive member. If these particles continue to stay on the edge of the cleaning blade, they will aggregate. It progresses and in the worst case it may melt and stick. Since the fixed matter at the edge portion is sandwiched between the cleaning blade and the photosensitive member, the cleaning blade is not sufficiently in contact with the photosensitive member in the vicinity of the portion where the fixed matter is sandwiched. It will cause defects.

In particular, it is known that if the coefficient of friction of the photosensitive member is 0.2 or more, the cleaning property is deteriorated. When such a photosensitive member is used, it has conventionally been difficult to prevent poor cleaning.
In the case of the two-component development method, a carrier adheres to and accumulates on the edge of the cleaning blade and the cleaning brush in addition to toner and paper powder. Since the carrier is iron powder, the surface of the photoconductor is easily damaged, and the surface roughness of the photoconductor increases with time, resulting in poor cleaning.

Furthermore, due to the frictional energy between the contact pressure of the cleaning blade and the photoconductor, the components of the fixed matter at the edge portion are transferred to the surface of the photoconductor to cause filming. Even at this time, if the coefficient of friction of the photosensitive member is high, the contact pressure of the cleaning blade and the energy of friction between the photosensitive member and the photosensitive member become larger, so that filming easily occurs and expands, and the blade edge It is easy for sticking to occur. Since the normal image forming process (charging, development, transfer, cleaning, charge removal) is not performed in the filming portion, image deterioration is caused. In particular, as the cleaning margin decreases, the leaked toner adheres to the filming portion and filming is reproduced, and the filming area is expanded.
In order to deal with such problems, it is effective as a countermeasure to periodically clean the blade edge to remove the sticking matter.
For example, there has been proposed a cleaning device that performs cleaning by sliding an elastic plate on a blade edge (see Patent Documents 1 and 2).
In addition, Patent Document 3 proposes a cleaning device that rubs the outer periphery of the brush roller against the blade edge.
Patent Document 4 proposes a cleaning device that reduces the contact pressure of the cleaning blade to reverse the photoreceptor.

Japanese Utility Model Publication No. 3-58668 JP-A-5-323846 Japanese Patent No. 2759813 JP 2000-155514 A Japanese Patent Laid-Open No. 9-15877

  In the cleaning apparatuses that perform cleaning by sliding the elastic plate against the blade edge disclosed in Patent Documents 1 and 2, the contact of the cleaning blade with the photosensitive member is the upstream edge in the photosensitive member rotating direction. This is a blade edge cleaning method that can be applied to a cleaning device of the (trailing contact) type that is performed, and the contact of the cleaning blade, which is currently mainstream, with the photosensitive member at the downstream edge of the photosensitive member rotation direction It is difficult to apply to a cleaning device that performs (counter contact).

  Further, in the cleaning device disclosed in Patent Document 3 that rubs the outer periphery of the brush roller against the blade edge, the contact of the cleaning blade with the photosensitive member, which is currently mainstream, is the downstream edge in the rotational direction of the photosensitive member. Although this method can be applied to the cleaning device of the counter contact method performed in step (2), the blade thickness is usually about 2 mm, and the brush roller has a problem that hair fall over time and the outer diameter fluctuates (shrinks). Therefore, it is difficult to guarantee the cleaning of the blade edge on the contact side of the cleaning blade with the photosensitive member.

  Further, in Patent Document 4, the foreign material adhered to and accumulated on the blade edge and sandwiched between the blade edge and the photosensitive member by the reverse rotation of the photosensitive member while the contact pressure of the cleaning blade is reduced is from the blade edge. A cleaning device to be cleaned has been proposed.

  However, the mechanism for increasing and decreasing the contact pressure of the cleaning blade is complicated, and it is difficult to prevent poor cleaning when a photoconductor having a friction coefficient of 0.2 or more is used.

  Also, due to the contact pressure of the cleaning blade and the energy of friction between the photosensitive member, the components of the fixed matter at the edge of the cleaning blade are transferred to the surface of the photosensitive member to cause filming. Even at this time, if the coefficient of friction of the photosensitive member is high, the contact pressure of the cleaning blade and the energy of friction between the photosensitive member and the photosensitive member become larger, so that filming easily occurs and expands, and the blade edge It is easy for sticking to occur. Since the normal image forming process (charging, development, transfer, cleaning, charge removal) is not performed in the filming portion, image deterioration is caused. In particular, as the cleaning margin decreases, the leaked toner adheres to the filming portion and filming is reproduced, and the filming area is expanded.

  Filming generated on the surface of the photoconductor is difficult to remove and prevent by going through a process of re-production as described above. If the surface of the photoconductor is made of a material having a low hardness, the edge of the cleaning brush with respect to the surface of the photoconductor or rubbing with the developer staying at the edge, or the cleaning brush if a cleaning brush is provided. The surface of the photoreceptor is gradually scraped and worn by rubbing, so that the surface of the photoreceptor is always refreshed and a new surface is exposed, so that the occurrence of filming can be suppressed. However, a-Si type photoreceptors known as long-life photoreceptors and photoreceptors containing inorganic particles in at least the outermost layer (for example, see Patent Document 5) have high surface hardness and low wear. When using a photoreceptor, it is difficult to prevent filming over time.

  An object of the present invention is to provide an image forming apparatus capable of performing stable cleaning by inhibiting the growth of fixed matter at the edge portion of the cleaning blade by a simple cleaning blade operation mechanism.

According to a first aspect of the present invention, there is provided an image forming apparatus comprising a cleaning blade that comes into contact with the photosensitive member at a position after separating the transfer paper from the photosensitive member with a pressure capable of scraping off deposits remaining on the surface of the photosensitive member. in, together with the photosensitive member at the time of image formation termination performs reverse rotation in the opposite direction you rotating the image formation, the contact pressure against the photosensitive member of the cleaning blade in the process of the photosensitive member is reversed from the steady pressure The pressure is reduced to a predetermined pressure or separated from the photosensitive member, and after the reverse rotation of the photosensitive member is completed, the cleaning blade is maintained in a reduced pressure or separated state and immediately before the photosensitive member starts normal rotation. Cleaning operation control means for pressurizing the contact pressure of the cleaning blade to the photoconductor to a steady pressure; and contact of the cleaning blade to the photoconductor. An actuator operation drive source for reducing the pressure from a steady pressure to a predetermined pressure, and pressurizing the contact pressure of the cleaning blade to the photoreceptor immediately before the photoreceptor starts to rotate forward is used for the photoreceptor. A driving force transmission system that is acquired from a driving source via a coupling means, and a torque limiter that is disposed in a part of the coupling means and controls the driving load torque to transmit rotation.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the actuator is an eccentric cam.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the torque limiter is integrated with a part of the connecting means.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the cleaning operation control means further performs at least 1 after the reverse rotation operation of the photoconductor at the end of the image formation. Perform forward and reverse rotations .

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the tip is formed in a loop shape as a cleaning means for cleaning the surface of the photoconductor after transfer, and the photoconductor is A cleaning brush that comes into contact is provided upstream of the cleaning blade in the photoconductor rotation direction, and a contact surface pressure of the cleaning brush with respect to the photoconductor is set to 50 gf / cm ² or more.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the cleaning brush is rotationally driven based on the driving force transmission system.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the friction coefficient μ of the photoconductor is set to μ = 0.2 or more.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the photoconductor is an amorphous silicon photoconductor.

  According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the photoconductor is a photoconductor containing inorganic particles in at least the outermost surface layer.

  According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, in addition to the photosensitive member and the cleaning member, at least one of other apparatuses related to image forming processing is the photosensitive member. And a cartridge together with a leaning member.

  According to the first aspect of the present invention, the reduction of the contact pressure of the cleaning blade or the separation from the photosensitive member during the reverse rotation operation after the end of the image forming operation means that the contact pressure during the image formation of the cleaning blade, Since the reverse operation can be performed in various states from the contact angle to the reduced pressure or the contact pressure at the time of separation from the photoconductor, the contact angle (the contact pressure and the contact angle are not at the time of separation), the reverse operation can be performed. In this state, foreign matters such as toner lump and paper dust adhering to and accumulating on the blade edge can be peeled off more efficiently, and the blade edge can be cleaned. Furthermore, after the reverse rotation operation is completed, the pressure is reduced or separated from the photosensitive member, so that no wasteful pressure is applied to the cleaning blade while the machine is stopped, the blade does not sag, and the predetermined contact angle and contact over time. Since the pressure can be maintained, good cleaning properties can be obtained over a long period of time. At the start of normal rotation, since the normal rotation is performed after returning to the contact pressure and contact angle at the time of image formation in advance, it is possible to prevent foreign matters such as paper dust cleaned at the time of reverse rotation from being caught in the blade edge again. In addition, since a series of operations of the cleaning blade is taken from a photoconductor drive source (photoconductor motor) for driving the photoconductor via a connecting means, a series of cleaning blade operation mechanisms can be simplified. Further, by arranging a torque limiter that controls the driving load torque and transmits the rotation to a part of the connecting means, for example, the photoconductor drive source (photoconductor motor) that drives the photoconductor runs away. Even if it is interrupted by the torque limiter, a series of cleaning blade operation mechanisms via the connecting means are not seriously damaged.

  According to the second aspect of the present invention, the cleaning blade actuator can be suitably applied to an eccentric cam.

  According to the third aspect of the present invention, the torque limiter for controlling the driving load torque and transmitting the rotation is integrated with a part of the connecting means, so that the series of cleaning blade operating mechanisms can be further simplified.

  According to the fourth aspect of the present invention, since the blade edge can be more effectively cleaned by performing the reverse rotation operation at least twice, a good cleaning property can be obtained over a long period of time.

According to the fifth aspect of the present invention, the cleaning brush having the tip with excellent cleaning performance formed into a loop shape is bitten into the photoconductor with a contact surface pressure of 50 gf / cm ² or more, so that it can be more reliably performed over time. A reduction in cleaning performance can be prevented.

  According to the sixth aspect of the present invention, even when an amorphous silicon photoconductor having a high surface hardness and little wear is used, the occurrence of filming over time can be prevented and the deterioration of the cleaning performance can be prevented.

  According to the seventh aspect of the present invention, even when a photosensitive member containing at least inorganic particles in the outermost surface layer and having high surface hardness and low wear is used, the occurrence of filming is prevented over time, and the cleaning performance is improved. A decrease can be prevented.

  According to the eighth aspect of the invention, the same effect as that of any one of the first to ninth aspects can be achieved.

  The best mode for carrying out the present invention will be described with reference to the drawings. First, FIG. 1 is a schematic layout diagram showing an example of an image forming apparatus for explaining the present embodiment. The illustrated example shows an example of application to a printer capable of optical writing corresponding to image information. However, the image forming apparatus can be applied not only to a printer but also to an electrophotographic copying machine, a facsimile machine, etc. It is.

  The printer 1 according to the present embodiment includes a drum-shaped photoconductor 2, and around the photoconductor 2, a charging device 3 for executing image forming processing in a rotating process, a writing device (optical path in FIG. 1). 4), a developing device 5, a transfer device 6 and a cleaning device 7 are arranged in the order of the electrophotographic process. Here, in the present embodiment, in addition to the photosensitive member 2 and the cleaning device 7, at least one device, for example, the charging device 3, is unitized as a process cartridge 20 and is attached to the printer main body 21 as shown in FIG. 2. On the other hand, it can be pulled out.

  As a result, basically, after the uniform charging process by the charging device 3 during the rotation of the photoconductor 2, an electrostatic latent image is formed on the photoconductor 2 by optical writing according to image information. Is subjected to visible image processing with toner supplied from the developing device 5 to form a toner image. The toner image is electrostatically transferred onto a transfer sheet fed from a paper feeding device (not shown) via the transfer device 6, and is conveyed to a fixing device (not shown) and fixed, thereby outputting an image. It is assumed to be a thing.

  Here, the photosensitive member 2 has the following configuration. That is, as the photosensitive member 2, a conductive support is heated to 50 to 400 ° C., and a vacuum deposition method, a sputtering method, an ion plating method, a thermal CVD method, a photo CVD method, a plasma CVD method, or the like is applied on the support. An amorphous silicon photoconductor having a photoconductive layer made of a-Si (hereinafter referred to as “a-Si photoconductor”) can be used. Among them, a plasma CVD method, that is, a method in which a source gas is decomposed by direct current, high frequency or microwave glow discharge to form an a-Si deposited film on a support is preferably used.

  The layer structure of the photoreceptor 2 is as follows. FIG. 3 is a schematic configuration diagram for explaining the layer structure of the photoconductor 2. The photoconductor 2 shown in FIG. 3A is made of a-Si: H, X on a support 2A and is made of light. A photoconductive layer 2B having conductivity is provided. The photoconductor 2 shown in FIG. 3B includes a photoconductive layer 2B ′ made of a-Si: H, X and having photoconductivity on an support 2A ′, and an amorphous silicon-based surface layer 2C ′. It is configured. A photoconductor (denoted by reference numeral 14 for convenience) shown in FIG. 3C has a photoconductive layer 14B made of a-Si: H, X and having photoconductivity on the support 14A, and an amorphous silicon surface. The layer 14C is composed of an amorphous silicon based charge injection blocking layer 14D. The photoconductor shown in FIG. 3D (indicated by reference numeral 14 'for convenience) has a photoconductive layer 14B' provided on a support 14A '. The photoconductive layer 14B 'includes a charge generation layer 14E' made of a-Si: H, X and a charge transport layer 14F ', and an amorphous silicon-based surface layer 14C' is provided thereon.

  The support used for the layer structure may be conductive or electrically insulating. Examples of the conductive support include metals such as Al, Cr, Mo, Au, In, Nb, Te, V, Ti, Pt, Pd, and Fe, and alloys thereof such as stainless steel. In addition, the surface on the side on which at least the photosensitive layer is formed of an electrically insulating support such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polystyrene, polyamide or other synthetic resin film or sheet, glass, ceramic, etc. A conductively treated support can also be used. The shape of the support may be a cylindrical or plate-like or endless belt with a smooth or uneven surface, and its thickness is appropriately determined so that a desired photoreceptor for an image forming apparatus can be formed. When flexibility as a photoreceptor for an image forming apparatus is required, it can be made as thin as possible within a range where the function as a support can be sufficiently exhibited. However, the support is usually 10 μm or more from the viewpoint of production and handling, such as mechanical strength.

  In the case of an amorphous silicon photoconductor, the injection preventing layer used for the layer structure is provided between the conductive support and the photoconductive layer as necessary, thereby effectively injecting charges from the conductive support side. To stop. That is, the charge injection blocking layer has a function of blocking charge injection from the support side to the photoconductive layer side when the photosensitive layer is subjected to a charging process with a certain polarity on its free surface. When charged, it has a so-called polarity dependency that does not exhibit such a function. In order to provide such a function, the charge injection blocking layer contains a relatively large number of atoms for controlling conductivity as compared with the photoconductive layer. The layer thickness of the charge injection blocking layer is preferably from 0.1 to 5 μm, more preferably from 0.3 to 4 μm, and most preferably from 0.5 to 0.5 in view of obtaining desired electrophotographic characteristics and economic effects. It is desirable to be 3 μm.

  The photoconductive layer in the layer structure is formed on the undercoat layer as necessary, and the layer thickness of the photoconductive layer is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic characteristics and economic effects, The thickness is preferably 1 to 100 μm, more preferably 20 to 50 μm, and most preferably 23 to 45 μm.

  The charge transport layer in the layer structure is a layer mainly having a function of transporting charges when the photoconductive layer is functionally separated. The charge transport layer includes at least silicon atoms, carbon atoms, and fluorine atoms as constituent elements, and is formed of a-SiC (H, F, O) including hydrogen atoms and oxygen atoms as required. Conductive properties, especially charge retention properties, charge generation properties, and charge transport properties. In the present embodiment, it is particularly preferable to contain an oxygen atom. The layer thickness of the charge transport layer is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic characteristics and economic effects. The charge transport layer is preferably 5 to 50 μm, more preferably 10 to 40 μm, and most preferably Is preferably 20 to 30 μm.

  The charge generation layer used in the layer structure is a layer mainly having a function of generating charges when the photoconductive layer is functionally separated. This charge generation layer is made of a-Si: H containing at least silicon atoms as components and substantially no carbon atoms and, if necessary, hydrogen atoms, and has desired photoconductive properties, particularly charge generation properties. , Has charge transport properties. The layer thickness of the charge generation layer is appropriately determined as desired from the viewpoint of obtaining desired electrophotographic characteristics and economic effects, etc., preferably 0.5 to 15 μm, more preferably 1 to 10 μm, optimally 1 to 1 μm. 5 μm.

  The surface layer in the layer structure is further provided with a surface layer on the photoconductive layer formed on the support as described above as necessary in the amorphous silicon photoconductor in the present embodiment. It is preferable to form a surface layer of the system. This surface layer has a free surface and is provided to achieve predetermined conditions mainly in moisture resistance, continuous repeated use characteristics, electrical pressure resistance, use environment characteristics, and durability. The layer thickness of the surface layer in the present embodiment is usually 0.01 to 3 μm, preferably 0.05 to 2 μm, and most preferably 0.1 to 1 μm. If the layer thickness is less than 0.01 μm, the surface layer is lost due to wear or the like during use of the photoreceptor, and if it exceeds 3 μm, electrophotographic characteristics such as an increase in residual potential are observed.

  However, not only the a-Si photoreceptor, but also a photoreceptor having high surface hardness and low wear, such as a photoreceptor containing inorganic particles in at least the outermost layer (see, for example, Patent Document 5). Good.

The surface friction coefficient μ of the photosensitive member 2 is set to μ = 0.2 or more, and the frictional resistance between the cleaning brush 8 and the cleaning blade 9 in the cleaning device 7 that contacts after the transfer is reduced. ing. As shown in FIG. 4, the measurement of the coefficient of friction on the surface of the photoreceptor 2 is a measurement method referred to as Euler belt type (Mechanical Engineering Handbook Basic Edition A3 Mechanics / Mechanical Mechanics P35 (issued in 1986)). In this method, for example, a weight (W) = 100 g is suspended,
μ = In (F / 100) / (π / 2))
Ask for.

  After the transfer, the photosensitive member 2 faces the cleaning device 7 so that residual toner, paper powder, various additives, and the like are removed, and residual charges are also removed, and then the charging device 3 uniformly applies. Charging is performed to prepare for another image forming process.

  The cleaning device 7 includes a cleaning brush 8 on the upstream side in the rotation direction of the photoconductor 2 in a unit 7A having an opening facing the photoconductor 2, and a urethane cleaning blade 9 on the downstream side. Are arranged so as to be in contact with each other. Further, the unit 7A in the cleaning device 7 includes a recovery coil 11 for sending the toner recovered from the photoreceptor 2 toward the transport pipe 10 for reuse as recycled toner, and an upstream of the rotation direction of the photoreceptor 2 in the unit 7A. A seal 12 for sealing the side entrance and a pressure release portion 7B in the unit 7A are provided. In FIG. 1, reference numeral 13 denotes a density sensor used when detecting the developer density.

  The cleaning brush 8 has a structure having a fur brush 8A planted on a rotatable roller surface, and details thereof are shown in FIG. In FIG. 5, the rotation direction of the cleaning brush 8 is set so that the fur brush 8 </ b> A can move in the opposite direction at a position in contact with the photoreceptor 2. As shown in FIG. 5 (a), the fur brush 8A is configured by flocking a base end of a loop-shaped wire material on a base cloth 8B. As shown in FIG. 5 (b), the base cloth 8B is a cleaning brush. 8 core metal 8C is wound and integrated.

  In the present embodiment, as shown in FIGS. 5B and 5C, the flocking direction of the fur brush 8A corresponds to the angle (θ) obtained in the direction in which the base fabric 8B is wound around the cored bar 8C. Furthermore, the density is such that fine residual toner, paper powder, or additives can be prevented from passing by the flocking interval.

The flocking density of the brush wire in the present embodiment is set to 50 to 300 loops / inch ² or more, and the contact surface pressure with respect to the photoreceptor 2 at the tip of the fur brush 8A is 50 gf / cm ² or more. The outer diameter (thickness) of the yarn used as the brush and the overhang length (loop length) from the base fabric 8B are set.

  In the present embodiment, such a fur brush 8 </ b> A moves while making line contact with the surface of the photoreceptor 2. This prevents the surface of the photoreceptor 2 from being damaged when the contact surface pressure described above is used, unlike a fur brush having a tip formed in a pile shape, and adheres to the surface of the photoreceptor 2 due to the surface pressure. In addition to toner and paper powder, additives finer than this can be wiped off. In addition, since the fur brush 8A is located upstream of the cleaning blade 9 in the rotation direction of the photosensitive member 2, when the toner scraped off by the cleaning blade 9 is dropped, it is received from the surface of the photosensitive member 2. It can be transported to a position that moves away.

The inventors of the present invention experimented on the cleaning effect by setting various thicknesses, loop lengths, and densities, which are mechanical characteristics of the cleaning brush 8,
Contact pressure gf / cm ² Cleaning performance judgment result 20 ×
40 ×
50 ○
70 ○
Got the result. As a result, the thickness of the raw yarn of the fur brush 8A was 250 to 300d / 15F, the loop length was ² to 4.5 mm, the density was 50 to 450 loop / inch ² , and the cleaning blade 9 This is a result when a low pressure and low humidity environment of 10 ° C. and 15% RH is set with a contact pressure with respect to the photoreceptor 2 of 21 gf / cm ² . Further, if the moving speed of the cleaning brush 8 at this time is set to about 0.5 to 1.6 times the speed of the photosensitive member 2, a good cleaning effect, that is, a state in which almost no residue is present can be obtained. I was able to. Note that the contact pressure of the cleaning blade 9 is not less than the above-described pressure when the high-temperature and high-humidity environment is used instead of the above-described low-temperature and low-humidity environment. It is also possible.

In addition, the inventors of the present invention experimented on the cleaning effect by setting various friction coefficients μ of the photosensitive member 2.
0.2 ○
0.3 ○
0.4 ○
Got the result. These results are all obtained when printing 300K sheets.

  Next, the cleaning blade 9 will be described. The cleaning blade 9 has a configuration in which the edge on the downstream side in the rotation direction of the photoconductor 2 is opposed to the photoconductor 2 and scrapes the residual deposits on the photoconductor 2 by so-called counter contact. The cleaning blade 9 is provided so as to be swingable with respect to the photosensitive member 2 via a pressure lever 9A that is rotatable about a shaft 9B. The pressurizing lever 9A is given a habit of contacting the cleaning blade 9 with a predetermined pressure at a constant pressure with respect to the photosensitive member 2 at all times by an elastic biasing means such as a tension spring 101, in this case, a pressure capable of scraping off residual deposits. Has been. Further, the cleaning blade 9 functions so that the cleaning blade 9 can be displaced in a direction away from the photoconductor 2 via the pressure lever 9A and is separated from the photoconductor 2 (or reduced pressure). ) Is provided with an eccentric cam 100 acting as an actuator.

  The eccentric cam 100 as an actuator is a means for separating the cleaning blade 9 in contact with the photosensitive member 2 from the photosensitive member 2 by utilizing the behavior of an elastic biasing means such as a tension spring 101. That is, when the rotary blade is displaced to a position that interferes with the pressure lever 9 </ b> A, the pressure lever 9 </ b> A is swung in a direction away from the photosensitive member 2.

  In this embodiment, the eccentric cam 100 operates when the photosensitive member 2 rotates after the image formation is completed and the photosensitive member 2 performs the reverse rotation operation that rotates in the opposite direction to that during image formation. The cleaning blade 9 is in a separated state (or reduced pressure state) with respect to the photoreceptor 2. As a result, even if the residual deposit scraped off from the surface of the photoreceptor 2 by the cleaning blade 9 at the time of cleaning remains restrained by the contact pressure by the cleaning blade 9, the constraint on the residual deposit is released. Will be removed.

  When the reverse rotation of the photoconductor 2 is completed, the cleaning blade 9 is maintained in a separated state (or a reduced pressure state) with respect to the photoconductor 2, but the photoconductor 2 starts normal rotation for re-image formation. Immediately before that, the eccentric cam 100 is returned to the original position where it comes into contact with the stopper 102, and the cleaning blade 9 comes into contact with the photoreceptor 2 with a pressure that can be scraped off. Such a series of operation control is executed as a function of the cleaning operation control means by a CPU (not shown) that controls the entire printer 1.

  According to the present embodiment, basically, the cleaning blade 9 is depressurized when the photosensitive member 2 is rotated in reverse. Therefore, in combination with the setting of the friction coefficient on the surface of the photosensitive member 2, It is possible to remove the residual deposits that are sandwiched between the surface of the body 2.

  That is, separating the cleaning blade 9 from the photosensitive member 2 (or reducing the contact pressure) during the reverse rotation after the image forming operation is completed means that the contact pressure at the time of image formation of the cleaning blade 9 The reversing operation can be performed in a state in which the contact pressure changes from the contact angle to the contact pressure and contact angle at the time of completion of separation (or during pressure reduction) from the contact angle to the contact angle (the contact pressure and the contact angle are absent at the time of separation). Therefore, foreign matters such as toner lump and paper dust adhering to and accumulating on the blade edge in various states can be peeled off more efficiently, and the blade edge can be cleaned. Further, after the reversing operation is completed, the state of being separated (or reduced pressure) from the photosensitive member 2 is maintained, so that no wasteful pressure is applied to the cleaning blade 9 while the machine is stopped, and there is no sag of the blade. Since the contact pressure can be maintained, good cleaning properties can be obtained over a long period of time. At the start of normal rotation, since the normal rotation is performed after returning to the contact pressure and contact angle at the time of image formation in advance, it is possible to prevent foreign matters such as paper dust cleaned at the time of reverse rotation from being caught in the blade edge again.

  It should be noted that it is more effective to perform at least one forward rotation and reverse operation after the execution of the reverse operation of the photosensitive member 2 at the end of image formation, that is, to perform the reverse operation at least twice. In particular, since the blade edge can be cleaned, a good cleaning property can be obtained over a long period of time.

  Next, the mechanism of the present embodiment for driving the eccentric cam 100 for contacting and separating the cleaning blade 9 will be described. First, as shown in FIG. 6, the eccentric cam 100 of the present embodiment is provided on one end side of the shaft 8B of the fur brush 8A, and is provided with the shaft 8B as a rotation center. On the other hand, as shown in FIG. 7, a brush gear 8D is provided on the other end side of the shaft 8B of the fur brush 8A (the back side of the process cartridge 20) via a coupling 8C. A photosensitive member gear 106 is provided on the photosensitive member shaft 103 of the photosensitive member 2 to mesh with a motor gear 105 that is rotationally driven by a photosensitive member motor 104 that is a photosensitive member driving source. The brush gear 8 </ b> D is connected to the motor gear 105 via the idle gear 107. The motor gear 105, the idle gear 107, the brush gear 8D, and the shaft 8B constitute a driving force transmission system 108 that transmits the driving force of the photosensitive member motor 104 to the eccentric cam 100 as an operation driving source. A torque limiter 109 containing magnetic powder is integrated between the eccentric cam 100 and the shaft 8B. At this time, since the load torque of the process cartridge 20 in this embodiment is 0.1 Nm (1 kgfcm) or less, the torque of the torque limiter 109 is set to 0.1 Nm. Accordingly, the tension is set so as to balance with the tension force of the tension spring 101.

  Therefore, in the operation of the eccentric cam 100 described above, the driving force of the photoconductor motor 104 is generated by a series of gears connected from the motor gear 105 through the idle gear 107 to the brush gear 8D and the far brush 8A at the rear of the process cartridge 20. Is transmitted to the shaft 8B (coupling 8C). Due to the rotation of the shaft 8B, the coaxial eccentric cam 100 is also rotationally displaced via the torque limiter 109.

  When the pressure lever 9 </ b> A is pivoted and displaced upward by the eccentric cam 100, the cleaning blade 9 is separated from the photoreceptor 2. At this time, since the eccentric cam 100 pushes up the pressure lever 9A against the tension spring 101, even if it receives a driving force (short-time reverse operation) from the photoreceptor motor 104 thereafter, the tension force by the tension spring 101 is obtained. Since the shaft 9B is set at a position where it acts as a stopper with respect to the eccentric cam 100, it does not rotate more than necessary. Incidentally, the control of the cleaning blade 9 in the case of the present embodiment only needs to be separated from the photosensitive member 2, so that the pressure lever 9 </ b> A, the eccentric cam 100, and the like do not require strict stop position accuracy.

  On the other hand, as an operation during normal image formation, the photosensitive drum 2 is rotated clockwise by the photosensitive drum motor 104 and the fur brush 8 is rotated counterclockwise, whereby the eccentric cam 100 on the shaft 8B is rotated counterclockwise. When rotated, the eccentric cam 100 moves away from the pressure lever 9A, so that the cleaning blade 9 supported by the pressure lever 9A comes into contact with the photoreceptor 2 with an appropriate contact pressure by the urging force of the tension spring 101. In this operation, after the eccentric cam 100 hits the stopper 103, the driving force from the photosensitive member motor 104 side is cut off by the torque limiter 109 containing magnetic powder, and the eccentric cam 100 is stopped (the photosensitive member 2 and the farthest member). The brush 8A continues to rotate).

  Therefore, according to the present embodiment, a series of operations of the cleaning blade 9 are taken from the photoconductor motor 104 that drives the photoconductor 2 via a series of connecting means such as a series of gears. Can be simplified. Furthermore, by arranging a torque limiter 109 that controls the driving load torque and transmits the rotation to a part of the connecting means, for example, even if the photoreceptor motor 104 driving the photoreceptor 2 runs away, Since it is interrupted by the torque limiter 109, there is no fatal damage to the series of cleaning blade operation mechanisms via the connecting means.

  In any case, with such a configuration, even when the coefficient of friction of the photosensitive member 2 is 0.2 or more and the margin for cleaning failure, filming, and adhesion to the blade edge is small, a good cleaning state can be maintained. Can do.

1 is a schematic layout diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. It is a schematic perspective view which shows the unit structural example. It is a typical block diagram which shows the layer structure of a photoreceptor. It is explanatory drawing which shows the example of an Euler belt type measuring device. It is explanatory drawing which shows the structural example of a fur brush. It is a schematic perspective view which shows a driving force transmission system etc. It is a perspective view which shows a gear system.

Explanation of symbols

2 Photoconductor 8 Cleaning brush 9 Cleaning blade 20 Cartridge 100 Actuator, eccentric cam 104 Photosensitive drive source 108 Driving force transmission system 109 Torque limiter

Claims (10)

In an image forming apparatus provided with a cleaning blade that comes into contact with the photosensitive member at a position after separating the transfer paper from the photosensitive member with a pressure capable of scraping off deposits remaining on the surface of the photosensitive member.
Together with the photosensitive member at the time of image formation termination performs reverse rotation in the opposite direction you rotating the image formation, the photosensitive member is the cleaning blade the contact pressure with respect to the photosensitive member from the steady pressure given in the process of reversal The pressure is reduced or separated from the photosensitive member, and after the reverse rotation of the photosensitive member is completed, the cleaning blade is maintained in a reduced pressure or separated state and immediately before the photosensitive member starts normal rotation. Cleaning operation control means for pressurizing the contact pressure of the blade to the photoconductor to a steady pressure;
An actuator for reducing the contact pressure of the cleaning blade to the photoconductor from a steady pressure to a predetermined pressure, and increasing the contact pressure of the cleaning blade to the photoconductor immediately before the photoconductor starts normal rotation. A driving force transmission system that acquires the operation driving source from the photosensitive member driving source via the coupling means;
An image forming apparatus, comprising: a torque limiter that is disposed in a part of the connecting unit and that transmits a rotation by controlling a driving load torque.   The image forming apparatus according to claim 1, wherein the actuator is an eccentric cam.   The image forming apparatus according to claim 1, wherein the torque limiter is integrated with a part of the connecting unit. 4. The cleaning operation control unit according to claim 1, wherein after the reverse rotation operation of the photosensitive member at the end of image formation, the forward rotation and reverse rotation are further performed at least once thereafter. Image forming apparatus.   As a cleaning means for cleaning the surface of the photoconductor after transfer, a cleaning brush having a tip formed in a loop shape and in contact with the photoconductor is provided upstream of the cleaning blade in the photoconductor rotation direction. 5. The image forming apparatus according to claim 1, wherein a contact surface pressure with respect to the body is set to 50 gf / cm 2 or more.   6. The image forming apparatus according to claim 5, wherein the cleaning brush is rotationally driven based on the driving force transmission system.   7. The image forming apparatus according to claim 1, wherein a friction coefficient μ of the photosensitive member is set to μ = 0.2 or more.   7. The image forming apparatus according to claim 1, wherein the photoconductor is an amorphous silicon photoconductor.   The image forming apparatus according to claim 1, wherein the photoconductor is a photoconductor containing inorganic particles in at least an outermost surface layer. Image forming apparatus.   10. In addition to the photosensitive member and the cleaning member, at least one of other apparatuses related to image forming processing is provided in one cartridge together with the photosensitive member and the leaning member. An image forming apparatus according to claim 1.

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