JP2005070206A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain miniaturization of an electrophotographic image forming apparatus, and, to improve user's operability. <P>SOLUTION: A developing unit 4 to which four developing devices 4Y, 4C, 4M and 4K can be loaded, a photoreceptor unit 2 including a photoreceptor 22 for carrying electrostatic latent images and a transfer unit 7 are arranged in almost vertical directions, and further, a paper feed cassette 5 is arranged under the units. A sheet-carrying path FF, a reverse carrying path FR and a fixing unit 9 are arranged on the front side of the apparatus (left in Fig.). Then, the image forming apparatus, having a small installation area, can be attained. Additionally, a part of a carrying unit 8 and the fixing unit 9 are attached to a front cover which can be opened/closed from the apparatus front side, then, the replacement of each unit and a jamming processing are performed by a work from the front side of the apparatus. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes a latent image carrier that can carry an electrostatic latent image, a developing device that stores toner, and an intermediate transfer member that temporarily carries a toner image obtained by developing the electrostatic latent image with toner. The present invention relates to an image forming apparatus provided.

  An electrophotographic image forming apparatus such as a printer, a copying machine, and a facsimile apparatus includes a latent image carrier capable of carrying an electrostatic latent image, a developer storing toner, and toner obtained by developing the electrostatic latent image with toner. The basic structure is an intermediate transfer member that temporarily holds an image, and the apparatus tends to be larger than other types of image forming apparatuses. In particular, if the number of colors and the size of the paper are increased, the size of the apparatus will increase. In order to solve this, various techniques for reducing the size of the apparatus have been proposed.

  For example, in the multicolor image forming apparatus described in Patent Document 1, an I / O cartridge and a developing cartridge in which a latent image carrier and an intermediate transfer body are integrated can be attached and detached through the same opening provided on the top surface of the apparatus. By doing so, usability is improved, the mechanism is simplified, and the apparatus is downsized. In order to obtain such an effect, this apparatus generally has the following configuration.

  FIG. 8 is a block diagram showing a schematic configuration of a conventional image forming apparatus. In the image forming apparatus 100, as shown in FIG. 8, the functional blocks of the development rotary 101, the latent image carrier 102, and the intermediate transfer body 103, to which a development cartridge is mounted, are arranged in a substantially horizontal direction. When the paper taken out from the paper feed cassette 105 provided below these is conveyed along a conveyance path 106 provided in a substantially horizontal direction, a toner image is transferred and discharged to the upper part of the apparatus. . In FIG. 8, an arrow indicated by a thick solid line represents a flow of toner or a toner image, while an arrow indicated by a broken line represents a flow of paper.

  Further, in this image forming apparatus 100, an openable / closable cover 107 is provided on the top surface of the apparatus, and each toner color developing cartridge mounted on the developing rotary 101, and the latent image carrier 102 and the intermediate transfer member 103 are integrated. All of the I / O cartridges 104 are detachable from the top of the apparatus. In FIG. 8, the arrow shown with a dashed-two dotted line has shown the attachment / detachment direction of each cartridge.

Japanese Patent Laid-Open No. 2002-244431 (FIG. 1)

  The above-described conventional image forming apparatus has the following problems to be solved. That is, since each functional block is arranged substantially in the horizontal direction, the installation area of the apparatus becomes large. Further, since the paper is transported substantially horizontally between the functional blocks and the paper feed cassette, the jam handling operation by the user becomes complicated.

  In such an arrangement, it is difficult to realize a double-sided printing function for forming images on both sides of a sheet. This is because the paper reciprocates between each functional block and the paper feed cassette, which increases the size of the device to secure the space for it, and makes the processing work when a jam occurs more complicated. Because it will end up.

  The present invention has been made in view of the above problems, and an object of the present invention is to reduce the size of an electrophotographic image forming apparatus and improve the operability of a user.

  In order to achieve the above object, the image forming apparatus according to the present invention can be equipped with at least one latent image carrier configured to carry an electrostatic latent image and at least one developer that stores toner. A developing unit that visualizes the electrostatic latent image on the latent image carrier as a toner image with the toner, and temporarily holds the toner image primarily transferred from the latent image carrier, and a recording material An intermediate transfer member that conveys the toner image to the secondary transfer position, and the latent image carrier is disposed substantially above the intermediate transfer member, and the developing unit is disposed substantially above the latent image carrier. It is characterized by.

  In the invention configured as described above, since the developing unit, the latent image carrier, and the intermediate transfer member are arranged substantially vertically, the installation area of the apparatus can be reduced, and the entire apparatus can be reduced in size. it can.

  Further, in this image forming apparatus, a recording material cassette that is provided substantially below the intermediate transfer member and that accommodates the recording material, and the recording material taken out from the recording material cassette are transported in a substantially vertical upward direction. And a recording material conveying means for conveying the ink to the upper part of the apparatus and discharging it to the outside of the apparatus, and the secondary transfer position may be provided on the conveying path. In this way, the recording material need only be conveyed in a substantially straight line from the lower part of the apparatus to the upper part, and the conveyance path can be simplified. As a result, the apparatus can be further downsized and the frequency of jam occurrence can be kept low.

  At this time, if the conveyance path is provided so that the recording material passes through the front side of the apparatus with respect to the developing unit, the latent image carrier, and the intermediate transfer body, the jamming of the recording material generated in the conveyance path is prevented. The processing operation can be easily performed by accessing from the front of the apparatus.

  A fixing unit for fixing the toner image to the recording material is further provided on the downstream side of the secondary transfer position on the transport path, and at least a part of the casing covering the front surface of the apparatus can be opened and closed. More preferably, a cover is provided so that at least a part of the recording material conveying means and the fixing unit are attached to the cover. In this way, the conveyance path is exposed by opening the cover, and access from the outside is facilitated, and jamming is further facilitated.

  Here, the recording material conveying means conveys the recording material that has passed through the fixing unit along a reverse conveying path substantially downward in the vertical direction, and sends the recording material again to the conveying path upstream of the secondary transfer position. When configured to be possible, a double-sided printing function for forming images on both sides of the recording material can be realized. Since this reverse conveyance path can also be provided on the front surface of the apparatus, good workability in jam processing is not impaired.

  In addition to the jam processing, the developing device can be attached / detached in addition to the jam processing if the developing device is attached / detached to / from the developing unit through an opening that opens to the front of the device with the cover open. It can be done by work from.

  Also, if the latent image carrier and the intermediate transfer member can be attached / detached from the front of the apparatus, most of the work required for maintenance of the apparatus can be performed only from the front of the apparatus. More preferable in terms.

  In order to achieve this, for example, the latent image carrier and the intermediate transfer body are integrally formed as a detachable unit that can be attached to and detached from the apparatus main body, and an opening that opens to the front of the apparatus when the cover is open The attaching / detaching operation of the attaching / detaching unit to / from the apparatus main body may be performed. By doing so, the replacement operation of the latent image carrier and the intermediate transfer member can be simultaneously performed by the operation from the front of the apparatus, and the operability is further improved.

  In addition, for example, the latent image carrier and the intermediate transfer member are configured to be detachable from the apparatus main body, and the latent image carrier to the apparatus main body through an opening opening in the front of the apparatus when the cover is open. The body and / or the intermediate transfer body may be attached and detached. By doing so, it is possible to individually replace the latent image carrier and the intermediate transfer member at necessary timings.

  In this case, it is desirable that the intermediate transfer member can be moved away from the latent image carrier with the cover open. In this way, when performing the attaching / detaching operation of one of the latent image carrier and the intermediate transfer member, it is possible to avoid the problem that one of the latent image carrier and the intermediate transfer member is damaged by being in contact with the other, and the workability is improved. Can be achieved.

  Each of the image forming apparatuses having the above-described configuration further includes an apparatus housing that holds the developing unit, and the developing unit has a plurality of the developing devices attached to the apparatus housing. It may be configured as a rotatable developing rotary. According to such a configuration, image formation can be performed while sequentially switching a plurality of developing devices by rotating the developing rotary. For example, if the toner colors of the developing units are different from each other, a color image can be formed.

  Here, the developing rotary is, for example, a substantially disk-like two side plates formed separately from each other, and each of the developing rotary is rotatably attached to one fixed shaft attached to the apparatus housing, The developing device may be engaged between the side plates from the radial direction of the side plate. According to such a configuration, since it is not necessary to provide a member for connecting the both side plates, more of the volume occupied by the developing rotary in the apparatus can be allocated to the developing device. Therefore, a larger-sized developing device having a large toner capacity can be mounted, and the frequency of replacement of the developing device can be reduced. Further, by providing the apparatus housing with a fixed shaft that passes between both side plates and passes through the central axis of the development rotary, it is possible to reduce the size of the apparatus housing while ensuring the rigidity of the apparatus housing.

  Further, as another example of the structure of the developing rotary, two side plates that are substantially disk-shaped and formed separately from each other are attached to the apparatus casing and have the same central axis. It can be structured such that it is rotatably attached to each of the fixed shafts, and the developing device is engaged between the side plates from the radial direction of the side plates. In this way, it is not necessary to provide a fixed shaft that passes between the side plates and passes through the central axis of the developing rotary, and a larger space for the developing device can be secured.

  FIG. 1 is a diagram showing a first embodiment of an image forming apparatus according to the present invention. This apparatus 1 forms a full color image by superposing four color toners (developers) of yellow (Y), cyan (C), magenta (M), and black (K), or black (K) toner. This is an image forming apparatus that forms a monochrome image using only the image forming apparatus. In this image forming apparatus, when an image signal is given from an external apparatus such as a host computer, a controller (not shown) controls each part of the apparatus to execute a predetermined image forming operation, and the sheet S corresponds to the image signal. Form an image.

  In this apparatus 1, the following seven units are provided in an apparatus housing 10: a photosensitive unit 2; a rotary developing unit 4; a paper feeding cassette 5; an exposure unit 6; a transfer unit 7; a transport unit 8 and a fixing unit 9. . Among these units, the photosensitive unit 2 and the transfer unit 7 are integrated (hereinafter, the unit in which these units are integrated is referred to as “photosensitive body / transfer unit” as necessary) and It is configured to be detachable.

  When an image signal is given from an external device to the image forming apparatus 1 configured as described above, the exposure unit 6 is provided in the photosensitive unit 2 in accordance with the image signal and rotates in the arrow direction D1 in FIG. A light beam L is applied to the photosensitive member 22 to be irradiated. The photosensitive member 22 is uniformly charged to a predetermined surface potential by a charging unit 23 to which a predetermined charging bias is applied. By exposing the surface with a light beam L, an electrostatic latent image corresponding to an image signal is obtained. Is formed on the surface of the photoreceptor 22.

  The electrostatic latent image formed in this way is developed with toner by the rotary developing unit 4. The developing unit 4 is provided so as to be rotatable about a rotation axis orthogonal to the paper surface of FIG. 1, and is configured as a cartridge that can be attached to and detached from the unit 4 and develops yellow for each color toner. A developing device 4C for cyan, a developing device 4C for cyan, a developing device 4M for magenta, and a developing device 4K for black. Then, based on a control command from the controller, the developing unit 4 is driven to rotate, and the developing units 4Y, 4C, 4M, and 4K selectively abut against the photosensitive member 22 or face each other with a predetermined gap therebetween. When the developer is positioned at a predetermined development position, a developing roller 44 provided in the developing unit and carrying toner of a selected color is disposed opposite to the photosensitive member 22 and a predetermined development bias is applied. Toner is applied to the surface of the photoreceptor 22. As a result, the electrostatic latent image on the photosensitive member 22 is visualized with the selected toner color.

  The toner image developed by the developing unit 4 as described above is primarily transferred onto the intermediate transfer belt 71 of the transfer unit 7 in the primary transfer region TR1. The transfer unit 7 includes an intermediate transfer belt 71 stretched around a plurality of rollers 72 to 74, and a drive unit (not shown) that rotates the intermediate transfer belt 71 in a predetermined rotation direction D2 by driving the rollers 72 to rotate. And detachable from the apparatus main body. When a color image is transferred to the sheet S, the color image is formed by superimposing the toner images of the respective colors formed on the photoreceptor 22 on the intermediate transfer belt 71.

  The monochrome or color image thus formed on the intermediate transfer belt 71 is conveyed to a predetermined secondary transfer region TR2 by the rotation of the intermediate transfer belt 71. Then, the color image is secondarily transferred onto the sheet S which is taken out one by one from the paper feeding cassette 5 and conveyed to the secondary transfer region TR2 along the conveyance path FF by the conveyance unit 8. The transport unit 8 includes a pickup roller 80 that picks up the sheet S from the sheet feeding cassette 5 one by one, a gate roller 81 that feeds the sheet S to the secondary transfer region TR2 at a predetermined timing, a secondary transfer roller 82, a discharge roller 83, and a later-described roller. A plurality of rollers 84 and 85 constituting the reversing conveyance path FR to be provided are provided. FIG. 1 shows the apparatus 1 viewed from the right side. As shown in FIG. 1, the transport unit 8 is provided on the front side of the apparatus 1 (left side in FIG. 1).

  By operating the transport unit 8 configured as described above, the sheet S on which the color image is formed is transported toward the upper side of the apparatus, and is provided on the upper surface portion of the apparatus main body via the fixing unit 9 and the discharge roller 83. The discharged tray unit 89 is discharged. On the other hand, when images are formed on both sides of the sheet S, the rotation direction of the discharge roller 83 is reversed when the sheet S on which the image is formed on one side as described above has passed through the fixing unit 9. As a result, the sheet S is transported downward along the reverse transport path FR. Then, it is placed again on the transport path FF before the gate roller 81. At this time, the image is transferred first on the surface of the sheet S that contacts the intermediate transfer belt 71 and transfers the image in the secondary transfer region TR2. It is the opposite surface. In this way, images can be formed on both sides of the sheet S.

  The image forming apparatus 1 is provided with cleaners 25 and 76 for removing the toner remaining on the surfaces of the photosensitive member 22 and the intermediate transfer belt 71. The cleaner 25 scrapes off the residual toner on the surface of the photoconductor 22 by a cleaner blade that contacts the photoconductor 22 and collects it in a waste toner tank. On the other hand, the cleaner 76 transfers residual toner on the surface of the intermediate transfer belt 71 to a cleaner roller that is applied with a predetermined cleaning bias and contacts the intermediate transfer belt 71 and collects it in a waste toner tank. The cleaner 25 and the cleaner 76 together with the photoconductor 22 and the charging unit 23 constitute the photoconductor unit 2.

  FIG. 2 is a block diagram showing the unit arrangement of the image forming apparatus. As shown in FIG. 2, in the image forming apparatus 1, the developing unit 4, the photosensitive unit 2, and the transfer unit 7 are arranged substantially in the vertical direction. Therefore, as is apparent from FIG. 1, when these units 4, 2 and 7 are projected onto the bottom surface of the apparatus, most of the images overlap each other. By adopting such an arrangement, the bottom area of the apparatus can be greatly reduced as compared with the conventional apparatus (FIG. 8) in which these are arranged in the horizontal direction.

  In addition, the sheet feeding cassette 5 is disposed below the transfer unit 7, and a conveyance unit 8 that conveys the sheet S along a substantially upward conveyance path FF is disposed on the front side of the apparatus (left side in FIG. 2). Therefore, it is possible to suppress an increase in the bottom area due to the provision of these. In FIG. 1, the paper feed cassette 5 has a structure protruding rearward of the apparatus (right side in FIG. 1). This shows an example of the configuration when the depth of the apparatus becomes shorter than the sheet length as a result of reducing the bottom area of the apparatus as described above, and the paper feed cassette 5 always protrudes rearward of the apparatus. It does not indicate that the paper feeding cassette 5 is pulled out toward the rear of the apparatus.

  Further, since the sheet S is configured to be conveyed in a substantially straight line from the sheet feeding cassette 5 at the lower part of the apparatus to the discharge tray 89 at the upper part, the conveying path FF is extremely simplified, and the frequency of jam occurrence is greatly reduced. Can do. Moreover, since the transport path FF is provided on the front side of the apparatus, even if a jam occurs, other units do not become an obstacle to the work, and jam processing can be performed by work from the front of the apparatus. It is also excellent in terms of user operability. Further, since the reverse conveyance path FR is also provided on the front surface of the apparatus, it is possible to easily perform a processing operation on a jam that occurs in the reverse conveyance path FR. In FIG. 2, an arrow indicated by a thick solid line represents the flow of the toner or the toner image, while an arrow indicated by a broken line represents the flow of the sheet S.

  FIG. 3 is a diagram showing a photoconductor / transfer unit exchange method in this embodiment. In the image forming apparatus 1, a front cover 11 that can be opened and closed is provided on the front side (left side in FIG. 3) of the apparatus housing 10. With the front cover 11 open, an opening AP for performing various maintenance operations opens on the front surface of the apparatus. Of the components constituting the fixing unit 9 and the transport unit 8, the secondary transfer roller 82 and the rollers 84 and 85 are attached to the front cover 11. With this configuration, when the front cover 11 is opened, the front of the photosensitive unit 2 and the transfer unit 7 is greatly opened. Therefore, the user can easily pull out these units 2 and 7 integrally, that is, the photosensitive member / transfer unit through the opening AP along the longitudinal direction thereof. In addition, a new unit can be easily mounted by the reverse operation. In this embodiment, a part of the fixing unit 9 and the transport unit 8 arranged in front of the photosensitive member / transfer unit are attached to the front cover 11 and moved together with opening and closing of the cover. In addition, the attaching / detaching work of the photosensitive member / transfer unit can be performed with excellent workability.

  At this time, the developing unit 4 is desirably positioned and fixed in a state where the developing roller provided in each developing device is separated from the photosensitive member 22. This is because damage to the developing roller and the photosensitive member due to contact when the unit is attached or detached can be avoided. In particular, as shown in FIG. 3, if the developing roller 44 closest to the photosensitive member 22 is positioned behind the photosensitive member 22 (on the right side in FIG. 3), the detachable photosensitive member unit 2 is provided. Contact with the developing roller 44 can be reliably avoided. Although not shown, in order to prevent the photosensitive unit 2 and the transfer unit 7 from being inserted / removed from the wrong direction and coming into contact with surrounding parts, a guide rail that regulates the attaching / detaching direction of these units is provided in the apparatus housing. 10 are preferably provided on both side surfaces.

  Further, with such a configuration, the parts that form the sheet conveyance path FF and the reverse conveyance path FR are exposed by opening the front cover 11, so even if a jam occurs on these paths, the front cover The jammed sheet S can be easily removed by opening 11.

  Further, as shown in FIG. 3, the sheet feeding cassette 5 can also be pulled out from the front of the apparatus, and the sheet S can be replenished by pulling out the cassette. The sheet feeding cassette 5 can be pulled out regardless of whether the front cover 11 is opened or closed.

  FIG. 4 is a diagram showing a developing device replacement method in this embodiment. Each developing device 4Y and the like can be attached to and detached from the developing unit 4 in a direction perpendicular to the rotation axis thereof. Therefore, as shown in FIG. 4, with the front cover 11 open, one developer (black developer 4K in the example of FIG. 4) can be taken out from or attached to the developing unit 4 from the front of the apparatus. This can be done through the part AP.

  As described above, in the image forming apparatus of this embodiment, the main work related to the maintenance of the apparatus, that is, the replacement of the developing device, the replacement of the photosensitive member / transfer unit, the jam processing, and the sheet supply to the sheet feeding cassette are all performed. It can be performed by an operation from the front of the apparatus, and the operability for the user is extremely good.

  FIG. 5 is a diagram showing the structure of the developing unit in this embodiment. The developing unit 4 forms a substantially cylindrical developing rotary with the four developing devices 4Y, 4C, 4M, and 4K attached thereto. More specifically, the developing unit 4 has the following structure. As shown in FIG. 5, a columnar fixed shaft 12 having both ends fixed to the left and right surfaces of the apparatus housing 10 is provided on the apparatus main body side. Then, two side plates 41 and 42 are provided on the fixed shaft 12 via sliding bearings 41a and 42a, respectively. Therefore, the side plates 41 and 42 are rotatable with respect to the fixed shaft 12. The peripheral portions of the side plates 41 and 42 are gears, and the drive gears 14 and 15 attached to both ends of the drive shaft 13 provided on the apparatus main body side mesh with each other. Therefore, when the drive shaft 13 is rotationally driven by a drive unit (not shown), the side plates 41 and 42 rotate in the same direction and at the same speed around the fixed shaft 12.

  Four developing devices 4Y, 4C, 4M and 4K can be mounted on the side plates 41 and 42 thus configured. More specifically, four guide rails 41b and 42b extending in the radial direction are provided on the opposing surfaces where the both side plates 41 and 42 face each other at intervals of 90 degrees. Therefore, along the guide rails 41b and 42b, the developing devices 4Y and the like having a substantially fan-shaped cross-sectional shape (see FIG. 1) are slid in the direction perpendicular to the fixed shaft 12, that is, in the radial direction of the side plates 41 and 42. Thus, the developing device 4Y and the like can be fitted or removed from the side plates 41 and 42. Then, with the four developing devices 4Y, 4C, 4M and 4K mounted between the side plates 41, 42, the developing device and the side plates are integrated to form a rotary developing unit 4 having a substantially cylindrical shape. doing.

  A developing rotary of a conventional image forming apparatus is generally one in which a predetermined number of developing devices are mounted on a frame configured to be rotatable with respect to the apparatus main body (for example, Japanese Patent Application Laid-Open An image forming apparatus described in Japanese Patent Application Publication No. 2003-5484. And in order to ensure the rigidity of a flame | frame, the idea of increasing the thickness of a flame | frame or providing a rib is made | formed. This limits the size of a developing device that can be mounted, and may limit the amount of toner that can be stored in each developing device.

  On the other hand, the developing unit 4 of this embodiment has four developing units having a substantially fan-shaped cross section with respect to the two side plates 41 and 42 that are rotatable with respect to the fixed shaft 12 attached to the apparatus housing 10. 4Y or the like is attached. Since both side plates 41 and 42 for holding the developing device are configured separately from each other, and connecting members and ribs for connecting them to each other are omitted, such a structure makes it possible to compare with the conventional apparatus. A large space SP1 for accommodating the developing device can be secured. As a result, the toner capacity of each developing device can be increased and the frequency of replacement of the developing device can be reduced, so that it is possible to reduce the labor and cost burden on the user for replacing the developing device.

  In addition, it is possible to effectively prevent the developing unit 4 from being twisted by rotationally driving the side plates 41 and 42 in the same direction and at the same speed. Furthermore, since the fixed shaft 12 that connects both side surfaces of the device housing 10 serves as a reinforcing material for the housing 10, it is possible to further reduce the size without reducing the rigidity of the device. It is.

  FIG. 6 is a diagram showing a modification of the structure of the developing unit. In this modification, instead of the fixed shaft 12 (FIG. 5) connecting both side surfaces of the apparatus housing 10, fixed shafts 121 and 122 are individually attached to the left and right side surfaces, respectively. As shown in FIG. 6, these fixed shafts 121 and 122 have a common central axis. Since the other structure is the same as that shown in FIG. 5, the same reference numeral is given to the same configuration, and the description thereof is omitted. Thus, in this modified example, since the fixed shaft that penetrates between both side plates is not provided, the developing device can occupy a larger space SP2 than the structure shown in FIG. These two types of structures can be used properly depending on whether the strength of the apparatus or the toner capacity of the developing device is important.

  As described above, in the image forming apparatus of this embodiment, each unit that occupies a large space, which is a main part of the apparatus, that is, the developing unit 4, the photosensitive unit 2, and the transfer unit 7 are arranged substantially vertically. Therefore, the bottom area of the device can be reduced. Further, the sheet feeding cassette 5 is provided below the transfer unit 7, and the conveyance unit 8 is configured so that the sheet conveyance path FF is substantially straight from the sheet feeding unit 5 at the lower part of the apparatus to the discharge tray 89 at the upper part of the apparatus. Therefore, the conveyance path is short and simple, and jam is unlikely to occur. Since the transport path is arranged on the front side of the apparatus and the openable front cover 11 is provided, even if a jam occurs, the processing can be easily performed from the front side of the apparatus. Further, by providing a reverse conveyance path FR that conveys the sheet S from the upper side to the lower side of the apparatus on the front side of the apparatus, a double-sided printing function can be easily realized without increasing the size of the apparatus, and jam processing, etc. The convenience of is not impaired.

  Further, since a part of the fixing unit 9 and the transport unit 8 are attached to the front cover 11, the photoconductor / transfer unit is largely exposed by opening the front cover 11, and the attaching / detaching work can be easily performed from the front of the apparatus. . In addition, since the attaching / detaching operation of the developing device 4Y and the like attached to the developing unit 4 can be performed from the front of the apparatus, all main maintenance operations can be performed from the front of the apparatus.

  Furthermore, since the rotary developing unit 4 has a structure in which four developing devices are attached between two side plates that are rotatably attached to the apparatus main body, a large space between both side plates can be used for the developing device. In addition, the toner capacity of each developing device can be increased. Thereby, it is possible to reduce the frequency of changing the developing device and the running cost.

  As described above, the image forming apparatus according to the present invention can be further downsized as compared with the conventional image forming apparatus, and has various advantages in terms of user operability. In other words, by applying the present invention, it is possible to realize an image forming apparatus that is small in size but has multiple functions (multicolor, double-sided printing) and is excellent in user operability.

  FIG. 7 is a diagram showing a second embodiment of the image forming apparatus according to the present invention. In the second embodiment, the photosensitive unit 2 and the transfer unit 7 can be individually attached to and detached from the apparatus main body, and due to this, a part of the mechanism is the image forming apparatus of the first embodiment described above. Is different. Since other apparatus configurations and operations are the same as those in the first embodiment, the same reference numerals are given to the same configurations, and descriptions thereof are omitted.

  As shown in FIG. 7, in the apparatus 1a of the second embodiment, the photosensitive unit 2 and the transfer unit 7 can be individually attached to and detached from the apparatus main body. By doing so, both units can be exchanged at appropriate timings, so that excellent effects can be obtained in maintaining the performance of the apparatus and reducing running costs. However, since the photosensitive member 22 and the intermediate transfer belt 71 are in contact with each other in a normal state, when any unit is attached or detached, there is a possibility that they are rubbed against each other to deteriorate or be damaged.

  In this embodiment, in order to solve this problem, as shown in FIG. 7, the transfer unit 7 swings within a predetermined range around the rotation axis of the roller 72. Thereby, the photoreceptor 22 and the intermediate transfer belt 71 can be separated as necessary. If the photoconductor unit 2 and the transfer unit 7 are attached and detached in this separated state, the above-mentioned problem of abrasion is avoided.

  For such a swing mechanism, for example, a lock lever for fixing these units is provided, and the transfer unit 7 moves to a contact side with the photosensitive member 22 (state shown by a solid line in FIG. 7) when locking the lock lever. On the other hand, it may be performed manually, such as moving to the separated side when released. Further, for example, the separation / contact operation may be automatically performed by opening / closing the front cover 11. In order to realize this, for example, a mechanism such as a crank lever or a cam that moves in accordance with the opening / closing operation of the front cover 11 may be provided, or the transfer unit 7 may be attached to the roller 72 without providing a special mechanism. When the front cover 11 is opened, the transfer unit 7 is separated from the photosensitive member 22 by the action of gravity when the front cover 11 is open, while the front cover 11 is closed when the front cover 11 is closed. The secondary transfer roller 82 attached to the cover may come into contact with the intermediate transfer belt 71 to push up the transfer unit 7 so as to come into contact with the photosensitive member 22.

  In these embodiments described above, the photosensitive member 22 corresponds to the “latent image carrier” of the invention, and the intermediate transfer belt 71 corresponds to the “intermediate transfer member” of the invention. The sheet S corresponds to the “recording material” of the present invention, and the paper feed cassette 5 functions as the “recording material cassette” of the present invention. Further, the transport unit 8 functions as the “recording material transport unit” of the present invention. Further, in the first embodiment, the photoconductor / transfer unit in which the photoconductor unit 2 and the transfer unit 7 are integrated corresponds to the “detachable unit” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, each of the above embodiments is an image forming apparatus having a double-sided printing function for forming images on both sides of the sheet S, but the present invention is not limited to this, and an image is formed only on one side of the sheet S. The present invention can also be applied to an image forming apparatus.

  Further, in each of the above-described embodiments, as shown in FIG. 5, the drive gears 14 and 15 that rotationally drive the rotary developing unit 4 are attached to the common drive shaft 13, and the developing unit is driven by the rotational drive of the drive shaft 13. 4 is configured to rotate. However, the present invention is not limited to such a structure. For example, the developing unit 4 is driven to rotate by a wheel train or other driving mechanism that is separately provided to transmit the driving force from the driving means. Also good.

  For example, each of the image forming apparatuses according to the above embodiments is an image forming apparatus provided with an intermediate transfer belt 71 as an “intermediate transfer member”. The present invention can also be applied to an image forming apparatus including the intermediate transfer member.

  Further, in each of the above embodiments, the present invention is applied to an apparatus that forms an image using toners of four colors of yellow, magenta, cyan, and black. However, the types and number of toner colors are limited to those described above. It is optional.

1 is a diagram illustrating a first embodiment of an image forming apparatus according to the present invention. 2 is a block diagram showing a unit arrangement of the image forming apparatus. FIG. It is a figure which shows the photoreceptor and transfer unit replacement | exchange method in this embodiment. It is a figure which shows the developing device replacement | exchange method in this embodiment. It is a figure which shows the structure of the developing unit in this embodiment. It is a figure which shows the modification of the structure of a developing unit. It is a figure which shows 2nd Embodiment of the image forming apparatus concerning this invention. It is a block diagram which shows schematic structure of the image forming apparatus of a prior art.

Explanation of symbols

2 ... photosensitive unit (detachable unit), 4 ... developing unit, 41,42 ... side plate, 4C, 4K, 4M, 4Y ... developing device, 5 ... feed cassette (recording material cassette), 7 ... transfer unit (detachable unit) ), 8... Transport unit (recording material transport means), 9... Fixing unit, 11 .. front cover, 22... Photoreceptor (latent image carrier), 71... Intermediate transfer belt (intermediate transfer body), FF. FR: reverse conveyance path, S: sheet (recording material), TR2: secondary transfer area (secondary transfer position)

Claims (12)

A latent image carrier configured to carry an electrostatic latent image; and
A developing unit capable of mounting at least one developing device for storing toner, and developing the electrostatic latent image on the latent image carrier as a toner image with the toner;
An intermediate transfer member that temporarily holds the toner image primarily transferred from the latent image carrier and conveys the toner image to a secondary transfer position to a recording material;
An image forming apparatus, wherein the latent image carrier is disposed substantially above the intermediate transfer member, and the developing unit is disposed substantially above the latent image carrier. A recording material cassette which is provided substantially below the intermediate transfer member and accommodates the recording material;
Recording material conveying means for conveying the recording material taken out from the recording material cassette to the upper part of the apparatus along a substantially vertically upward conveying path and discharging the recording material to the outside of the apparatus, wherein the secondary transfer position is the conveying The image forming apparatus according to claim 1, wherein the image forming apparatus is provided on a path.   The image forming apparatus according to claim 2, wherein the transport path is provided so that the recording material passes through a front side of the apparatus with respect to the developing unit, the latent image carrier, and the intermediate transfer member. The image forming apparatus further includes a fixing unit provided on the downstream side of the secondary transfer position on the conveyance path for fixing the toner image to the recording material, and at least a part of a casing covering the front surface of the apparatus can be opened and closed. It is a cover of
The image forming apparatus according to claim 3, wherein at least a part of the recording material conveying unit and the fixing unit are attached to the cover.   The recording material conveying means is capable of reverse conveyance in which the recording material that has passed through the fixing unit is conveyed along a reverse conveyance path that is substantially downward in the vertical direction, and is sent to the conveyance path again on the upstream side of the secondary transfer position. The image forming apparatus according to claim 4, which is configured.   6. The image forming apparatus according to claim 4, wherein the developing unit is attached to and detached from the developing unit through an opening that opens to the front of the apparatus when the cover is open. The latent image carrier and the intermediate transfer body are configured as a detachable unit that can be detachably attached to the apparatus main body,
7. The image forming apparatus according to claim 4, wherein the attaching / detaching operation of the attaching / detaching unit to / from the apparatus main body is performed through an opening opening in the front surface of the apparatus when the cover is open. The latent image carrier and the intermediate transfer member are configured to be detachable from the apparatus main body,
7. The apparatus according to claim 4, wherein the latent image carrier and / or the intermediate transfer member is attached to or detached from the apparatus main body through an opening that opens to the front of the apparatus when the cover is open. The image forming apparatus described in 1.   The image forming apparatus according to claim 8, wherein the intermediate transfer member is movable away from the latent image carrier when the cover is open. Further comprising an apparatus housing for holding the developing unit,
The image forming apparatus according to claim 1, wherein the developing unit is configured as a developing rotary that is mounted with a plurality of the developing devices and is rotatable with respect to the apparatus housing. The developing rotary is
Two side plates that are substantially disc-shaped and formed separately from each other are each rotatably attached to one fixed shaft attached to the device housing,
The image forming apparatus according to claim 10, wherein the developing unit is engaged between the side plates from the radial direction of the side plate. The developing rotary is
Each of the two side plates that are substantially disc-shaped and formed separately from each other is rotatably attached to each of two fixed shafts that are attached to the apparatus housing and have the same central axis,
The image forming apparatus according to claim 10, wherein the developing unit is engaged between the side plates from the radial direction of the side plate.

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