JP3840487B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an electrophotographic image forming apparatus .

  2. Description of the Related Art Image forming apparatuses such as copying machines and printers that employ an electrophotographic method have a photoreceptor on which the toner image is formed on the outer circumferential surface, and the toner image is formed on the outer circumferential surface of the photoreceptor disposed around the photoreceptor. Each member such as a transfer roller and an intermediate transfer belt for transferring a toner image formed on the outer peripheral surface of the photosensitive member to a recording medium as a charging device, a developing device, a cleaning device as an image forming means concerned. Have.

  Each of these members has a lifetime determined as a standard depending on the material and usage, and is replaced according to the lifetime. Moreover, it may be necessary to replace even before the end of the useful life due to dust adhesion or scratches.

  Regarding the configuration for replacing each member, it is possible to replace each member individually, but in that case, the frequency of the replacement work increases and it takes time and effort. Other members located adjacent to each other may be damaged. In view of this, an image forming apparatus in which a process cartridge in which a photosensitive member, a charging device, a developing device, a cleaning device, and the like are unitized is configured and these members are replaced at once has been widely used.

  However, in recent years, an image forming apparatus has been proposed that is capable of extending the life of the photosensitive member, which is the most expensive member, and can be replaced separately from other members. It has become.

  When the photoconductor is configured to be exchangeable separately from other members in this way, the image quality formed on the recording medium is deteriorated due to the outer peripheral surface of the photoconductor being scratched. In this case, only the photoconductor is replaced.

JP 2002-108049 A JP2000-227688

  However, when the outer peripheral surface of the photosensitive member is scratched, the cause of the scratch is a transfer member that is pressed against the outer peripheral surface of the photosensitive member, such as an intermediate transfer belt, a recording medium conveyance belt, or a transfer roller. There are many cases. For this reason, even if the damaged photoconductor is replaced, if the transfer member causing the scratch is not replaced, the replaced photoconductor is damaged again in a short time, and the image quality is lowered again. Things are likely to happen.

  For example, in a color image forming apparatus having an intermediate transfer belt, when a foreign matter containing paper dust or residual toner adheres to the outer peripheral surface of the intermediate transfer belt, the foreign matter is pressed against the outer peripheral surface of the photosensitive member. The spot-like scratches gradually become streaks by making spot-like scratches on the outer peripheral surface and repeatedly pressing the foreign matter against the photoconductor. When streaky scratches are attached to the outer peripheral surface of the photoconductor, a large amount of toner adheres to the streaky scratches on the photoconductor, and it corresponds to the streaky scratches on the recording medium. Appear as black streaks.

  In addition, when foreign matter enters between the roller that rotates the intermediate transfer belt and the inner peripheral surface of the intermediate transfer belt, a convex portion is generated on the outer peripheral surface side of the intermediate transfer belt due to the influence of the foreign matter. As the portion is pressed against the outer peripheral surface of the photoconductor, dot-like scratches are formed on the outer peripheral surface of the photoconductor, and when the convex portion repeatedly presses against the outer peripheral surface of the photoconductor, the dot-like scratches gradually become streaks. It becomes a shape.

  In a color image forming apparatus in which a recording medium is conveyed by a recording medium conveyance belt without using an intermediate transfer belt, recording is performed because the recording medium is interposed between the recording medium conveyance belt and the photosensitive member during image formation. The medium conveying belt is hardly pressed directly against the outer peripheral surface of the photosensitive member. However, the recording medium transport belt is pressed against the outer peripheral surface of the photosensitive member at a portion between the recording media transported back and forth. For this reason, when a foreign object adheres to the outer peripheral surface of the recording medium transport belt, or a foreign object enters between the recording medium transport belt and the rotation driving roller, there is a convex portion toward the outer peripheral surface of the recording medium transport belt. If this occurs, streak-like scratches will be made on the outer peripheral surface of the photoreceptor as in the case of the intermediate transfer belt.

  Even in a single-color image forming apparatus having a transfer roller that is pressed against the outer peripheral surface of the photoconductor without using an intermediate transfer belt or a recording medium conveying belt, if foreign matter adheres to the outer peripheral surface of the transfer roller, Scratches caused by foreign matter are attached to the outer peripheral surface of the photoreceptor.

  It is an object of the present invention to provide a transfer that is highly likely to cause damage to the photoreceptor and the outer peripheral surface of the photoreceptor when image quality is deteriorated due to damage to the outer periphery of the photoreceptor. It is to replace the working member as one body, reduce the labor of the replacement work, and prevent the outer peripheral surface of the photoreceptor from being repeatedly damaged.

  Another object of the present invention is that when the cause of the image quality deterioration is not in the transfer member but only in the photosensitive member, for example, in the case where a film with a charged product or the like is formed on the outer peripheral surface of the photosensitive member. In other words, it is possible to replace only the photoconductor alone.

According to a first aspect of the present invention, there is provided an image forming apparatus that primarily transfers toner images formed on a plurality of photoconductors to an intermediate transfer member and then secondarily transfers the toner images to a recording medium. The photosensitive member and the intermediate transfer member are integrated and have a unit that is detachably attached to the main body of the image forming apparatus, and the photosensitive member is detachably held with respect to the unit. The image forming apparatus main body has a second unit including a plurality of image forming means for performing development on each of the photosensitive members, and is separate from a unit in which the plurality of photosensitive members and the intermediate transfer member are integrated. It is characterized in that it is detachably attached to.

  Here, when the quality of the image formed on the recording medium is deteriorated due to scratches on the outer peripheral surface of the photosensitive member, the cause of the scratches on the outer peripheral surface of the photosensitive member is a foreign matter fixed to the transfer member, In many cases, it is a convex portion or the like generated on the outer peripheral surface side of the transfer member because foreign matter has entered between the inner peripheral surface of the transfer member and a roller for driving the transfer member.

Therefore, when the quality of the image formed on the recording medium is deteriorated due to scratches on the outer peripheral surface of the photoconductor, the photoconductor is damaged on the outer peripheral surface and the photoconductor is damaged. The intermediate transfer member with high possibility can be replaced with the main body of the image forming apparatus as a whole, and the work required for replacing the parts causing the deterioration of the image quality can be reduced. The image quality can be reliably restored without repeating the occurrence of the image quality degradation.

Examples of the image forming means other than the intermediate transfer member disposed around the photosensitive member include a charger, a developing device, and a cleaning device. Some cleaningless image forming apparatuses do not have a cleaning device. Each of these image forming means often has a shorter service life than the photoconductor and intermediate transfer member, and the replacement frequency is higher than that of the photoconductor and transfer member.

Therefore, a plurality of image forming means can be exchanged integrally by attaching and detaching the image forming unit in which these image forming means are integrated to the main body case. It is reduced. Further, the image forming unit can be detached from the main body case without removing the transfer unit from the main body case.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect , the intermediate transfer belt is disposed on the upper side, and the photoconductor is disposed on the lower side.

  Therefore, when a transfer unit including a plurality of photoconductors and an intermediate transfer belt is removed from the main body case for maintenance or the like, the photoconductor is shielded from light by the intermediate transfer belt, so that deterioration of the photoconductor due to exposure is suppressed. Is done.

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 photosensitive member is detachably held with respect to the unit that is detached from the image forming apparatus main body. It is characterized by.

  Therefore, when the cause of the image quality deterioration is not the transfer member but only the photoconductor, after removing the transfer unit from the main body case, replace only the photoconductor causing the image quality deterioration. The other photoconductors and transfer members can be used continuously.

Invention of claim 5, characterized in that the image forming apparatus according to claim 1, wherein the charger is provided as one of the imaging means, the charger is a non-contact manner with respect to the photosensitive member And

  Therefore, even if a foreign substance adheres to the charger, it does not occur that the foreign substance is pressed against the photoconductor and damages the outer peripheral surface of the photoconductor. For this reason, when the outer peripheral surface of the photoconductor is damaged, the charger is not the cause of the damage. When the transfer unit is replaced because the outer peripheral surface of the photoconductor is damaged, the charger Need not be replaced at the same time.

The invention of claim 6 mounting is characterized in that in the image forming apparatus according to claim 1, wherein the developing unit is provided as one of the imaging means, the developing device is a non-contact manner with respect to the photosensitive member And

The invention of claim 7, wherein, in the image forming apparatus according to claim 1, wherein the cleaning device is provided as one of the imaging means, characterized in that the cleaning device is a brush contact system.

According to an eighth aspect of the present invention, in the image forming apparatus according to the second aspect , a cleaning device is provided as one of the image forming means, and the cleaning device is a brush contact system.

  Therefore, even if a foreign substance adheres to the cleaning device, it does not occur that the foreign substance is pressed against the photoconductor and damages the outer peripheral surface of the photoconductor. For this reason, when the outer peripheral surface of the photoconductor is damaged, the cause of the damage is not in the cleaning device. When the transfer unit is replaced because the outer peripheral surface of the photoconductor is damaged, the cleaning device Need not be replaced at the same time.

Invention of claim 8, wherein, in the image forming apparatus according to claim 1, in that said plurality of photosensitive body and the intermediate transfer member to the upper side of the second unit is installed units together Features.

  Therefore, the transfer unit can be detached from the main body case without removing the developing unit from the main body case. Further, the structure for mounting the image forming unit and the transfer unit in the main body case can be simplified.

The invention of claim 9, wherein, in the image forming apparatus according to claim 1, wherein the cleaning device is provided as one of the imaging means, the opening of the cleaning device in the second unit is opened upward It is characterized by that.

  Here, “the opening of the cleaning device opens upward” means that the inclination angle of the opening surface of the opening with respect to the horizontal plane is smaller than 90 °.

  Therefore, even when the image forming case is taken out from the main body case with the opening of the cleaning device opened, waste toner is prevented from spilling from the opening.

According to the image forming apparatus of the first aspect of the present invention, when the quality of the image formed on the recording medium is deteriorated due to scratches on the outer peripheral surface of the photoconductor, The intermediate transfer member , which is likely to cause damage to the photoconductor, can be replaced integrally with the image forming means other than the transfer member disposed around the photoconductor. In addition, it is possible to reduce the time and effort required to replace the parts that cause the degradation of the image quality, and it is possible to reliably restore the image quality without repeating the occurrence of the similar degradation of the image quality. When the cause of the image quality deterioration is not in the intermediate transfer member but only in the photoconductor, it is possible to replace only the photoconductor alone. And a second unit that includes at least a plurality of image forming means for performing development on each of the plurality of photoconductors, separately from the unit in which the plurality of photoconductors and the intermediate transfer member are integrated. Since it is detachably attached to the main body of the image forming apparatus, a plurality of image forming means can be integrated by detaching a unit in which image forming means other than the transfer member are integrated with the main body case. The image forming means can be reduced in labor, and the second unit without removing the unit in which the plurality of photosensitive members and the intermediate transfer member are integrated from the main body case. The unit can be removed from the main case.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect , the intermediate transfer belt is disposed on the upper side, and the photosensitive member is disposed on the lower side thereof. When the transfer unit including the transfer belt is removed from the main body case for maintenance or the like, the photosensitive member is shielded from light by the intermediate transfer belt, so that deterioration of the photosensitive member due to exposure can be suppressed.

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 photoconductor is detachable from the unit in a state of being detached from the main body of the image forming apparatus. Therefore, if the cause of the image quality degradation is not in the transfer member but only in the photoconductor, after removing the unit from the main body case, remove only the photoconductor causing the image quality degradation. The other photoconductors and transfer members can be used continuously.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect , a charger is provided as one of the image forming means, and the charger is a non-contact type with respect to the photoconductor. Even if a foreign object adheres to the charger, it does not occur that the foreign object is pressed by the photoconductor and damages the outer peripheral surface of the photoconductor, and the charger is replaced at a timing different from the replacement timing of the transfer unit. Can do.

According to a sixth aspect of the present invention, in the image forming apparatus according to the first aspect , a developing device is provided as one of the image forming means, and the developing device is a non-contact type with respect to the photoconductor. Even if foreign matter adheres to the developing unit, the foreign matter is not pressed against the photoconductor to damage the outer peripheral surface of the photoconductor, and the photoconductor should be replaced at a timing different from the transfer unit replacement timing. Can do.

According to the seventh aspect of the present invention, in the image forming apparatus according to the first aspect , a cleaning device is provided as one of the image forming means, and since this cleaning device is a brush contact system, foreign substances are present in the cleaning device. Even if it is fixed, the foreign matter is not pressed against the photoconductor to damage the outer peripheral surface of the photoconductor, and the cleaning device can be replaced at a timing different from the transfer unit replacement timing.

According to an eighth aspect of the present invention, in the image forming apparatus according to the first aspect , a unit in which the plurality of photosensitive members and the intermediate transfer member are integrated is installed above the second unit. Therefore, the unit in which the plurality of photosensitive members and the intermediate transfer member are integrated from the main body case can be removed from the main body case without removing the second unit from the main body case. The structure in which the unit and the unit in which the plurality of photosensitive members and the intermediate transfer member are integrated can be simplified in the main body case.

According to a ninth aspect of the present invention, in the image forming apparatus according to the first aspect , a cleaning device is provided as one of the image forming means, and the opening of the cleaning device in the second unit opens upward. Therefore, even when the second unit is taken out from the main body case with the opening of the cleaning device being opened, it is possible to prevent waste toner from spilling from the opening.

  A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view showing an outline of an appearance of a color printer as an image forming apparatus, and FIG. 2 is a front view showing an outline of the internal structure.

  Four image forming units 3 (3Y, 3C, 3M, and 3B), an exposure device 4, and an intermediate transfer belt 5 that is a transfer member are arranged at a substantially central portion in the main body case 2 of the color printer 1. Has been. Each image forming unit 3 is a part for forming an image (toner image) of a different color. In the description of the specification and drawings relating to these image forming unit 3 and the components of the image forming unit 3, Y, C , M, and B subscripts indicate yellow, cyan, magenta, and black colors, respectively.

  The four image forming units 3Y, 3C, 3M, and 3B have different colors of images formed because the colors of the toners used are different, and the basic structure is the same.

  Each image forming unit 3 includes a photoreceptor 6 (6Y, 6C, 6M, 5B) that is rotationally driven in the direction of an arrow, and a charger 7 (7Y, 7) that is one of the image forming means disposed around the photoreceptor 6. 7C, 7M, 7B), developing device 8 (8Y, 8C, 8M, 8B) which is one of image forming means, cleaning device 9 (9Y, 9C, 9M, 9B) which is one of image forming means, and the like. It is configured.

  The exposure device 4 emits a laser beam and writes an electrostatic latent image corresponding to the image data on the outer peripheral surface of the photoconductor 6 with the laser beam.

  The photoreceptor 6 is formed of an aluminum cylinder having a diameter of about 30 to 100 mm and an organic semiconductor layer that is a photoconductive material provided on the outer peripheral surface thereof. By irradiating the outer peripheral surface of the photoconductor 6 with laser light emitted from the exposure device 4, an electrostatic latent image corresponding to image data is written on the outer peripheral surface of the photoconductor 6. An irradiation slit 10 for irradiating the outer peripheral surface of each photoconductor 6 with laser light emitted from the exposure device 4 is provided between the charger 7 and the developing unit 8 in each image forming unit 3. Yes.

  The charger 7 uniformly charges the outer peripheral surface of the photoconductor 6, and a non-contact type is used for the photoconductor 6.

  The developing device 8 supplies toner to the photosensitive member 6, and the supplied toner adheres to the electrostatic latent image written on the outer peripheral surface of the photosensitive member 6, thereby forming an electrostatic latent image on the photosensitive member 6. A toner image is visualized, and a non-contact type is used for the photoreceptor 6.

  The cleaning device 9 cleans residual toner adhering to the outer peripheral surface of the photoconductor 6, and a brush contact type in which a brush contacts the outer peripheral surface of the photoconductor 6 is employed. Further, the cleaner 9 is positioned so that the opening 9a (see FIG. 9) opens upward, that is, the inclination angle of the opening 9a with respect to the horizontal plane is smaller than 90 °.

  The intermediate transfer belt 5 is a loop belt formed with a resin film or rubber having a thickness of 50 to 600 μm as a base, and has a resistance value that enables transfer of a toner image formed on the photoreceptor 6. . The intermediate transfer belt 5 is supported by rollers 11, 12, and 13 and is driven to rotate in the arrow direction. Four transfer rollers 14 for transferring the toner image on each photoconductor 6 onto the intermediate transfer belt 5 are arranged on the inner peripheral surface side (inside the loop) of the intermediate transfer belt 5. On the outer peripheral surface side (outside the loop) of the intermediate transfer belt 5, a cleaning device 15 that cleans residual toner, paper dust, and the like attached to the outer peripheral surface of the intermediate transfer belt 5 is disposed.

  Below the four image forming units 3 and the exposure device 4 in the main body case 2, a paper feed cassette 16 on which recording media (paper) S are stacked and held is disposed. The recording media S stacked and held in the paper feed cassette 16 are separately fed in order from the highest one.

  In the main body case 2, a transport path 17 is formed through which the recording medium S separated and fed from the paper feed cassette 16 is transported. On the conveyance path 17, a registration roller 18, an intermediate transfer roller 19, a fixing device 20, a paper discharge roller 21 and the like are arranged.

  The registration roller 18 is a roller that is rotationally driven intermittently at a predetermined timing. By intermittently driving the registration roller 18, the recording medium S that has been transported to the position of the registration roller 18 and stopped is sent to a transfer position sandwiched between the intermediate transfer belt 5 and the intermediate transfer roller 19. At this transfer position, the toner image on the intermediate transfer belt 5 is transferred to the recording medium S.

  The fixing device 20 is a portion that fixes the toner image transferred onto the recording medium S to the recording medium S by applying heat and pressure. The recording medium S on which the toner image has been fixed in the process of passing through the fixing device 20 is discharged onto a discharge tray portion 22 formed on the upper surface portion of the main body case 2 by a discharge roller 21.

  Above the four image forming units 3 and the intermediate transfer belt 5 in the main body case 2, toner containers 23 (23Y, 23C, 23M, 23B) containing toner to be supplied to the image forming unit 3 are detachable. A toner container mounting portion 24 to be mounted is provided. The toner in each of the toner containers 23Y, 23C, 23M, and 23B mounted on the toner container mounting unit 24 is directed to each of the image forming units 3Y, 3C, 3M, and 3B that forms an image having the same color as the toner. The toner is transported by a toner transport mechanism (not shown).

  Of the above-described intermediate transfer belt 5, photosensitive member 6, charger 7, developing device 8, cleaning device 9 and the like, the four photosensitive members 6 and the intermediate transfer belt 5 are integrally held to constitute a transfer unit 25. Has been. Further, the charging unit 7, the developing unit 8 and the cleaning unit 9 for each image forming unit 3 are integrally held to form an image forming unit 26. Four image forming units 26 for each image forming unit 3 are placed on one image forming unit tray 26a (see FIGS. 4 and 6), and the image forming unit 26 is mounted on the image forming unit tray 26a. It is detachably attached.

  FIG. 4 shows a state in which the front cover 27 provided on the front side of the main body case 2 is opened. By opening the front cover 27, the transfer unit 25, the image forming unit tray 26a on which the four image forming units 26 are placed, and the toner container mounting portion 24 are exposed, and the transfer unit 25, the image forming unit 26, and the toner are exposed. The container 23 can be exchanged. Note that the transfer unit 25 and the image forming unit 26 are brought into contact with and separated from each other by moving an image forming unit tray 26a on which the image forming unit 26 is placed between the transfer unit 25 and the image forming unit 26 in the vertical direction. An approach / separation mechanism (not shown) is provided. This contact / separation mechanism is configured to move the image forming unit tray 26a downward in accordance with the operation of opening the front cover 27 and to raise the image forming unit tray 26a in accordance with the operation of closing the front cover 27. Yes. Instead of such a contact / separation mechanism interlocked with the opening / closing operation of the front cover 27, a contact / separation mechanism for raising and lowering the image forming unit tray 26a by a cam operated by a lever may be provided.

  FIG. 5 shows a state where the transfer unit 25 is pulled out of the main body case 2, and FIG. 6 shows a state where the image forming unit 26 is pulled out of the main body case 2. FIG. 3 is a front view showing an outline of the internal structure of the color printer when the transfer unit 25 is pulled out of the main body case 2.

  In this embodiment, the transfer unit 25 and the image forming unit 26 are separately drawn out of the main body case 2 as an example. However, the transfer unit 25 and the image forming unit 26 are integrated with each other. The transfer unit 25 may be separated from the image forming unit 26 and replaced after being pulled out, and the image forming unit 26 may be replaced after the transfer unit 25 is separated from the image forming unit 26. . According to the modified example having such a configuration, it is not necessary to provide a contact / separation mechanism between the transfer unit 25 and the image forming unit 26, and the transfer unit 25 is placed above the image forming unit 26 at a predetermined interval. The structure for attaching the image forming unit 26 and the transfer unit 25 in the main body case 2 can be simplified.

  As shown in FIGS. 7 and 8, the transfer unit 25 includes a pair of front and rear intermediate transfer belt holding plates 28a and 28b, a transfer roller holding side plate 29a for holding a pair of front and rear color image transfer rollers 14Y, 14C and 14M, 29b, and a frame body including a stay (not shown) that connects these intermediate transfer belt holding side plates 28a and 28b and the transfer roller holding side plates 29a and 29b. Rollers 11, 12, 13 and a black transfer roller 14B are held between the intermediate transfer belt holding side plates 28a, 28b. A slide rail 30 that is slid when the transfer unit 25 is attached to and detached from the main body case 2 is fixed to stays (not shown) on both sides provided as a part of the transfer unit 25 (see FIG. 5). A resin cover 31 is fixed to the outer periphery of the upper side of the intermediate transfer belt holding side plates 28a and 28b. The cover 31 can be held between the front and upper surfaces of the cover 31 when the transfer unit 25 is attached to or detached from the main body case 2. Handles 32 and 33 are provided. A spring 34 for urging the transfer roller 14 toward the photosensitive member 6 is provided at the shaft portion of the transfer roller 14.

  The black transfer roller 14 </ b> B is disposed at a position where the intermediate transfer belt 5 is pressed against the outer peripheral surface of the photoreceptor 6. The color transfer rollers 14Y, 14C, and 14M, together with the transfer roller holding side plates 29a and 29b, are positioned to move the intermediate transfer belt 5 away from the outer peripheral surface of the photosensitive member 6 (see FIG. 7), and the intermediate transfer belt 5 is moved to the photosensitive member. 6 is provided so as to be switchable to a position to be pressed against the outer peripheral surface.

  The holding structure of the photoreceptor 6 in the transfer unit 25 will be described in detail. A photoreceptor front holder 35 is fixed to the front intermediate transfer belt holding side plate 28a, and an outer ring of a ball bearing 36 is press-fitted into the photoreceptor front holder 35. A spring holder 37 is press-fitted into the inner ring of the ball bearing 36, and one end of a pressure spring 38 is inserted and fixed to the spring holder 37. A photoconductor rear holder 39 is fixed to the rear intermediate transfer belt holding side plate 28b. The rear flange portion 6b of the photoreceptor 6 is inserted into the rear photoreceptor holder 39 with a sufficient clearance. The front flange portion 6 a of the photoreceptor 6 is inserted into the other end of the pressure spring 38. As a result, the individual photoconductors 6 are held between the pre-photoreceptor holder 35 and the post-photoreceptor holder 39 by the pressing force of the pressurizing spring 38, and the individual photoconductors 6 are moved relative to the transfer unit 25. Removably held.

  Four main body side photoconductor shaft holders 40 are fixed to an inner side plate (not shown) in the main body case 2. The main body side photoconductor shaft holder 40 holds a photoconductor shaft 42 via two ball bearings 41, and a driving coupling 43 is press-fitted into the photoconductor shaft 42. The photoconductor shaft 42 is formed with a rear side (portion into which the ball bearing 41 and the drive coupling 43 are press-fitted) of φ12 mm and a front side of φ10 mm, and extends in the horizontal direction.

  A structure for mounting the transfer unit 25 holding the intermediate transfer belt 5 and the four photosensitive members 6 in the main body case 2 will be described in detail with reference to FIGS. By sliding the transfer unit 25 into the main body case 2, the front end portion of the photosensitive member shaft 42 is inserted from the rear flange portion 6 b of the photosensitive member 6 toward the front flange portion 6 a. By sliding the transfer unit 25 to a position where the φ12 mm portion of the photoconductor shaft 42 is fitted in the hole 44 having a diameter of φ12 mm formed in the rear flange portion 6 b, the rear side of the photoconductor 6 is placed in the main body case 2. The driving coupling 43 is meshed with a meshing portion 43a formed on the rear flange portion 6b, so that a driving force can be transmitted from the driving portion (not shown) to the photosensitive member 6. Further, a part of the post-photoreceptor holder 39 is fitted into the outer ring portion of the ball bearing 41, whereby the entire transfer unit 25 is positioned with respect to the main body case 2.

  The front side of the photoreceptor shaft 42 is attached to a hole 45 (φ10 mm) formed in the front flange portion 6a, a hole 46 (φ11 mm) formed in the spring holder 37, and the intermediate transfer belt holding side plate 28a. It is inserted into the inner ring (φ10 mm) of the bearing 47.

  As shown in FIG. 6, the image forming unit tray 26a is fixed with slide rails 48 that are located on both sides thereof and are slid when the image forming unit tray 26a is attached to and detached from the main body case 2, and the image forming unit tray 26a is formed on the front portion. A handle 49 that can be gripped when the image unit tray 26a is attached to and detached from the main body case 2 is provided.

  In such a configuration, when printing a color image, toner images of different colors are formed on the outer peripheral surface of the photoconductor 6 of each image forming unit 3, and the intermediate transfer belt 5 is pressed against the outer peripheral surface of each photoconductor 6. As a result, the toner image on the photosensitive member 6 is transferred onto the intermediate transfer belt 5 in a superimposed manner, and a color toner image is formed on the intermediate transfer belt 5. The color toner image formed on the intermediate transfer belt 5 is recorded in the process in which the recording medium S separated and fed from the paper cassette 16 passes through the nipping position between the intermediate transfer belt 5 and the intermediate transfer roller 19. Transferred to the medium S. The color toner image transferred onto the recording medium S is fixed while the recording medium S passes through the fixing device 20, and the recording medium S on which the color toner image is fixed is discharged to the discharge tray unit 22. Is done.

  In such a color printer 1, the quality of an image formed on the recording medium S may be deteriorated due to various causes. One of the causes of such a decrease in image quality is the outer peripheral surface of the photoreceptor 6. May be scratched. When the outer peripheral surface of such a photoreceptor 6 is damaged, the cause of the damage is often the intermediate transfer belt 5.

  For example, when a foreign matter containing paper dust or residual toner adheres to the outer peripheral surface of the intermediate transfer belt 5, when the foreign matter is pressed against the outer peripheral surface of the photosensitive member 6, a dot-like scratch is formed on the outer peripheral surface of the photosensitive member 6. Is attached. When the image is formed, the contact position between the intermediate transfer belt 5 and the photosensitive member 6 is hardly the same, and the foreign matter on the intermediate transfer belt 5 is formed on the outer peripheral surface of the photosensitive member 6 every time the image is formed. Pressing is repeated at different positions, and the scratches on the outer peripheral surface of the photoreceptor 6 gradually grow into streak-like scratches. When the outer peripheral surface of the photosensitive member 6 has a streak-like scratch, a large amount of toner adheres to the scratched portion on the outer peripheral surface of the photosensitive member 6, and the streak-like scratch on the recording medium S. The part corresponding to the wound appears as a black streak.

  Further, when foreign matter enters between the rollers 11, 12, 13 for rotating the intermediate transfer belt 5 and the inner peripheral surface of the intermediate transfer belt 5, the outer peripheral surface side of the intermediate transfer belt 5 is affected by the foreign matter. A convex portion is formed on the outer peripheral surface of the photosensitive member 6, and the convex portion is pressed against the outer peripheral surface of the photosensitive member 6, thereby causing a dot-like scratch on the outer peripheral surface of the photosensitive member 6. When the image is formed, the contact position between the intermediate transfer belt 5 and the photosensitive member 6 is hardly the same, and the convex portion on the intermediate transfer belt 5 is the outer peripheral surface of the photosensitive member 6 every time the image is formed. The scratches on the outer peripheral surface of the photoreceptor 6 gradually grow into streak-like scratches, and portions corresponding to the streak-like scratches appear as black streaks on the recording medium S. .

  In such a case, if only the photoconductor 6 is replaced, the replaced photoconductor 6 is again scratched in a short period of time, and the quality of the formed image is degraded. Therefore, in such a case, all the photosensitive members 6 that are damaged and the intermediate transfer belt 5 that causes the damage must be replaced together, and the transfer unit 25 is replaced as a whole.

  When replacing the transfer unit 25, the front cover 27 is opened as shown in FIG. With the opening operation of the front cover 27, the image forming unit tray 26 a is lowered downward by the contact / separation mechanism, and the image forming unit 26 is separated from the transfer unit 25.

  Therefore, the handle 32 provided at the front portion of the transfer unit 25 is gripped, and the transfer unit 25 is slid to the front side as shown in FIG. The transfer unit 25 is removed from the main body case 2. At the time of removal, as shown in FIG. 7, the four photosensitive members 6 are each extracted from the photosensitive member shaft 42.

  After the transfer unit 25 is removed from the main body case 2 in this way, it is mounted in the main body case 2 in the reverse procedure of removing the prepared new transfer unit 25 (see FIG. 8), and the front cover 27 is closed. To do.

  Therefore, when the image quality formed on the recording medium S is deteriorated due to scratches on the outer peripheral surface of the photoconductor 6, there is a high possibility that the photoconductor 6 is scratched and the scratch is caused. The intermediate transfer belt 5 can be exchanged integrally, and the labor of the exchange work can be greatly reduced as compared with the case where the photoreceptor 6 and the intermediate transfer belt 5 are individually exchanged. Further, this replacement operation can be performed without damaging the surface of the photoconductor 6 or exposing the photoconductor 6. Regarding the point that exposure of the photosensitive member 6 can be prevented at the time of replacement work, the structure of the transfer unit 25 is such that the intermediate transfer belt 5 is disposed on the upper side and the photosensitive member 6 is disposed on the lower side. The transfer belt 5 can sufficiently exhibit a light shielding function with respect to the photoreceptor 6.

On the other hand, the cause of the deterioration of the image quality formed on the recording medium S is not because the foreign matter adhering to the intermediate transfer belt 5 or the convex portion formed on the intermediate transfer belt 5 damages the outer peripheral surface of the photoreceptor 6. In some cases, each photoconductor 6 is present. For example, a case where a film of a chargeable organism adheres to the outer peripheral surface of the photoreceptor 6. In such a case, as shown in FIG. 7, after the transfer unit 25 is removed from the main body case 2, it is possible to replace only the photosensitive member 6 that causes a reduction in image quality. This replacement of the photosensitive member 6 resists the pressing force of the pressing spring 38 on the photosensitive member 6 held by the pressing force of the pressing spring 38 between the holder 35 before the photosensitive member and the holder 39 after the photosensitive member. Then, the rear flange portion 6 b is removed from the rear photoreceptor holder 39 by moving to the pressure spring 38 side, and then the front flange portion 6 a is removed from the end of the pressure spring 38. The new photoconductor 6 may be attached in the reverse order. After the photoconductor 6 and the pressure spring 38 are set in the photoconductor front holder 35, the rear side of the photoconductor 6 is pressed with the pressure spring 38 compressed. By inserting the photoconductor front holder 35 into the mounting hole 35a of the intermediate transfer belt holding side plate 28a, the photoconductor front holder 35 slides the hole 35a forward by the force of the pressure spring 38. Then, it is prevented from coming off from the hole 35a.

  Therefore, when a certain photoconductor 6 causes a decrease in image quality, only the photoconductor 6 can be replaced, and other photoconductors 6 or intermediate transfer that do not cause a decrease in image quality. Since the belt 5 can be used continuously, it does not cause unnecessary high costs. Even when it takes a long time to take the transfer unit 25 out of the main body case 2 in order to replace such a specific photoconductor 6, the intermediate transfer belt 5 is arranged on the upper side and the photoconductor is on the lower side. 6 is arranged, the intermediate transfer belt 5 can sufficiently exhibit a light shielding function with respect to the photosensitive member 6, and deterioration of the photosensitive member 6 that is not replaced by exposure can be suppressed.

  Further, in this color printer 1, after opening the front cover 27 and lowering the image forming unit tray 26a downward as shown in FIG. 4, the image forming unit tray 26a is pulled out to the front side as shown in FIG. be able to. Then, each image forming unit 26 is removed by removing from the image forming unit tray 26 a the image forming unit 26 in which the charger 7, the developing device 8, and the cleaner 9 for each image forming unit 3 are integrally held. Can be replaced with a new one.

  The charging unit 7, the developing unit 8, the cleaning unit 9, and the like are often set to have a shorter service life than the photoconductor 6 and the intermediate transfer belt 5, and the replacement frequency is also higher than that of the photoconductor 6 and the intermediate transfer belt 5. Is expensive. For this reason, the charging device 7, the developing device 8, the cleaning device 9 and the like are integrated as an image forming unit 26 so that they can be replaced at once, and the photosensitive member 6 and the intermediate transfer belt 5 are removed from the main body case 2. Since the charging device 7, the developing device 8, the cleaning device 9 and the like can be easily replaced, it is possible to easily replace them.

  Further, in each image forming unit 26, the opening 9 a of the cleaning device 9 is positioned so as to open upward, so that the image forming unit 26 is opened in the state where the opening 9 a of the cleaning device 9 is opened. Even when the toner is taken out of the toner, waste toner is prevented from spilling from the opening 9a.

  In the present embodiment, a drum-shaped photoconductor has been described as an example of the photoconductor 6, but a belt-shaped photoconductor may be used.

Next, a second embodiment of the present invention will be described with reference to FIG. Incidentally, the same parts as described in FIGS. 1 to 9 are denoted by the same reference numerals, also omitted explained.

  In the color printer 50 which is an image forming apparatus, an upper structure 52 is provided at the upper part of the main body case 2 so as to be rotatable about the support shaft 51, and is rotated about the support shaft 53 on the side of the main body case 2. A side structure 54 is provided freely. The upper structure 52 is provided with a toner container mounting portion 24 to which the toner container 23 (23Y, 23C, 23M, 23B) is detachably mounted. The side structure 54 is provided with the fixing device 20.

  A transfer unit 55 is attached to the lower surface of the upper structure 52 so as to be slidable in the direction of the arrow. The basic structure of the transfer unit 55 is the same as that of the transfer unit 25 described in the first embodiment, and includes an intermediate transfer belt 5 held by a frame body 56 and four photoconductors 6. On both sides of the frame body 56, there are provided handles 57 that are gripped when the transfer unit 55 is slid in the direction of the arrow and attached to or detached from the upper structure 52. Each photoconductor 6 is detachably attached to the frame 56.

  In the main body case 2, four image forming units 26 arranged at positions facing the respective photoreceptors 6 of the transfer unit 55 attached to the upper structure 52 rotated to the closed position are detachable. Has been placed.

  In such a configuration, when replacing the photoreceptor 6 with the outer peripheral surface scratched and the intermediate transfer belt 5 that is highly likely to cause the scratch, the upper structure 52 is opened as shown. The transfer unit 55 is removed from the upper structure 52 by rotating to the position and pulling out the transfer unit 55 in the direction of the arrow. After the transfer unit 55 is removed, a prepared new transfer unit 55 is attached to the upper structure 52, and then the upper structure 52 is closed.

  On the other hand, when the cause of the deterioration in the quality of the image formed on the recording medium S is in the individual photoconductors 6, only the photoconductor 6 causing the deterioration in image quality is replaced, and another photoconductor 6 or The intermediate transfer belt 5 can continue to be used.

  When the image forming unit 26 is exchanged, the image forming unit 26 is exposed by rotating the upper structure 52 to the upper rotating position shown in the drawing, and the exposed individual image forming units 26 are changed as necessary. Can be replaced with a new one.

1 is a perspective view illustrating an outline of an appearance of a color printer according to a first embodiment of the present invention. It is a front view which shows the outline of the internal structure. It is a front view showing an outline of an internal structure in a state where a transfer unit is removed from a main body case. It is a perspective view which shows the outline of the external appearance of the state which open | released the front cover. It is a perspective view which shows the outline of the external appearance of the state which pulled out the transfer unit. FIG. 3 is a perspective view illustrating an outline of an appearance in a state where the developing unit is pulled out together with the developing unit tray. It is a vertical side view which shows the outline of the state which removed the transfer unit out of the main body case. It is a vertical side view which shows the outline of the state which attached the transfer unit in the main body case. It is a longitudinal front view showing a schematic structure of the developing unit. It is a front view which shows the outline of the external appearance of the color printer of the 2nd Embodiment of this invention.

Explanation of symbols

2 Main body case 5 Transfer member, intermediate transfer member 6 Photoconductor 7 Image forming means, charger 8 Image forming means, developing device 9 Image forming means, cleaning device 9a Opening 25 Transfer unit 26 Image forming unit 61 Transfer member, Recording medium conveyance belt 62 Transfer unit 71 Transfer member, transfer roller 72 Transfer unit S Recording medium

Claims (9)

An image forming apparatus that primarily transfers toner images formed on a plurality of photoconductors to an intermediate transfer member, and then secondarily transfers the intermediate transfer member to a recording medium.
The plurality of photoconductors and the intermediate transfer member are integrated and have a unit that is detachably attached to the image forming apparatus main body, and the photoconductor is detachably held with respect to the unit.
A second unit having a plurality of image forming means for performing development on at least each of the plurality of photosensitive members, and the image separately from a unit in which the plurality of photosensitive members and the intermediate transfer member are integrated. An image forming apparatus, wherein the image forming apparatus is detachably attached to a forming apparatus main body.   The image forming apparatus according to claim 1, wherein the intermediate transfer member is an intermediate transfer belt.   The image forming apparatus according to claim 2, wherein the intermediate transfer belt is disposed on an upper side, and the photoconductor is disposed on a lower side thereof.   The image forming apparatus according to claim 1, wherein the photoconductor is detachably held with respect to the unit that is detached from the main body of the image forming apparatus.   The image forming apparatus according to claim 1, wherein a charger is provided as one of the image forming units, and the charger is a non-contact type with respect to the photoconductor.   The image forming apparatus according to claim 1, wherein a developing unit is provided as one of the image forming units, and the developing unit is a non-contact type with respect to the photosensitive member.   The image forming apparatus according to claim 1, wherein a cleaning device is provided as one of the image forming units, and the cleaning device is of a brush contact type.   The image forming apparatus according to claim 1, wherein a unit in which the plurality of photosensitive members and the intermediate transfer member are integrated is installed above the second unit.   The image forming apparatus according to claim 1, wherein a cleaning device is provided as one of the image forming units, and an opening of the cleaning device in the second unit is opened upward.

Images