JP2006098776A - Image forming apparatus and image forming unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming unit which are capable of facilitating component replacement work. <P>SOLUTION: A laser printer 1 is provided with the image forming unit 20 which can be drawn out of a main body casing 2 and can be attached to and detached from the main body casing 2. Since a direction of detaching a developing cartridge 22 from a frame 21 is inclined toward the front side being a drawing-out direction, the developing cartridge 22 can be easily replaced. When the image forming unit 20 detached from the main body casing 2 is lifted in a vertical direction with a grip part 58 in a hand, the developing cartridge 22 hardly slips off the frame 21 because the detaching direction of the developing cartridge 22 is inclined toward the drawing-out direction (upward). An optical path of laser light L from a scanner part 18 is made approximately parallel with the detaching direction of the developing cartridge 22 to maximize the capacity of the developing cartridge 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus and an image forming unit.

  A so-called tandem type is known as one type of image forming apparatus using electrophotographic technology. This comprises a photoconductor for each color of yellow, magenta, cyan, and black, and an image forming process component such as a developing cartridge and a charger around it, and each photoconductor is supplied with toner of each color supplied from each developing cartridge. The image formation is performed by transferring the color toner images formed thereon onto the conveyed paper. In such an image forming apparatus, as a configuration for enabling replacement of consumables such as a developing cartridge, for example, an openable / closable cover is provided on the upper surface of the main body casing, and the developing cartridge and the like are arranged in the vertical direction below the cover There are things that are held detachably. In addition, there is a drawer in which a developing cartridge or the like is loaded so that the drawer can be pulled out horizontally from the main body casing. In this case, the cartridge is detachably attached to the drawer in a vertical direction. Similarly, there is a drawer in which a developing cartridge or the like is mounted so as to be pulled out vertically with respect to the main body casing. In this case, the cartridge is attached and detached in the horizontal direction.

  As described above, in the conventional configuration, the direction of attaching and detaching the cartridge is extremely limited, and depending on the positional relationship between the operator's body and the apparatus, it may not always be easy to attach and detach the cartridge, and there is room for improvement. was there.

  The present invention has been completed based on the above-described circumstances, and an object thereof is to provide an image forming apparatus and an image forming unit capable of facilitating replacement of parts.

  As a means for achieving the above object, an image forming apparatus according to the invention of claim 1 is provided with a plurality of sets of developing units and photoconductors arranged in parallel, and each of the developing units is supplied by the developer supplied from the developing units. A tandem image forming apparatus configured to form a visible image on a photoreceptor and transfer the visible image to a recording medium. The image forming apparatus can be pulled out of the main body casing and the main body casing. An image forming unit provided; and a plurality of cartridges including at least one of the developing unit or the photosensitive member and detachably held on a frame of the image forming unit; and the frame of the cartridge This is characterized in that the direction from which the image forming unit is detached is inclined toward the drawing direction of the image forming unit.

  A second aspect of the present invention is characterized in that, in the first aspect, the image forming unit is detachable from the main body casing.

  According to a third aspect of the present invention, the image forming unit according to the second aspect is characterized in that a grip portion for hand grip at the time of attachment / detachment is provided.

  According to a fourth aspect of the present invention, the grip portion is provided at an end portion in the pull-out direction of the image forming unit, and the image forming unit removed from the main body casing is connected to the grip portion. Is characterized in that it can be lifted in a posture in which the end on the opposite side to the pull-out direction is on the lower side.

  According to a fifth aspect of the present invention, in the printer according to any one of the first to fourth aspects, each of the plurality of cartridges includes the developing device, and each of the photoconductors is provided in the main body casing. Exposure means for irradiating each with light to form an electrostatic latent image is provided, and the developing devices are arranged side by side between the exposure means and the photosensitive members. It is characterized in that the optical path of light from the exposure means to each photoconductor is substantially parallel to the mounting / removal direction of each cartridge.

  In the image forming apparatus according to the sixth aspect of the present invention, a plurality of sets of developing devices and photosensitive members are provided in parallel, and a visible image is formed on each of the photosensitive members by the developer supplied from the developing devices. A tandem type image forming apparatus configured to transfer the visible image onto a recording medium, and irradiates light to each of the main body casing and each of the photoconductors provided in the main body casing. And an exposure unit that forms an electrostatic latent image and one of the developing units, and the main unit is arranged such that each of the developing units is arranged side by side between the exposure unit and each of the photosensitive members. A plurality of cartridges detachably provided in the casing, and the attachment / detachment direction of each cartridge is inclined with respect to the vertical direction, and an optical path of light from the exposure means to each of the photoconductors Attaching each cartridge Characterized in place that is in a direction substantially parallel.

  According to a seventh aspect of the invention, there is provided a transfer belt according to any one of the first to sixth aspects, wherein a transfer belt for transferring a toner image on each of the photosensitive members to the recording medium is provided in the main body casing. The photoconductors are arranged at positions facing the transfer belt when the image forming unit is mounted, and the photoconductors are separated from the transfer belt when the image forming unit is pulled out. However, it has characteristics.

  According to an eighth aspect of the present invention, in the apparatus according to any one of the first to seventh aspects, a supply tray on which the recording medium is loaded is provided in the main body casing so that the supply tray can be pulled out. This is characterized in that the pull-out direction is the same as the pull-out direction of the supply tray.

  A ninth aspect of the present invention provides the apparatus according to any one of the first to sixth aspects, wherein the supply tray is disposed in a lower portion of the main body casing and is loaded with a plurality of the recording media, and the upper side of the supply tray. And a transfer belt that transports the recording medium fed from the supply tray in the lateral direction, and the photosensitive members that are disposed on the transfer belt and transported on the transfer belt. An image forming unit for transferring a toner image on each photoconductor to the recording medium by facing the recording medium, and a discharge tray provided on the upper surface of the main body casing and for discharging the recording medium fed from the transfer belt. It is characterized by the provision.

  According to a tenth aspect of the present invention, there is provided the apparatus according to any one of the first to sixth aspects, wherein the image forming unit is configured to be drawn upward with respect to the main body casing. .

  According to an eleventh aspect of the present invention, there is provided the printer according to any one of the first to tenth aspects, wherein the cartridge is configured separately from the photoconductor.

  According to a twelfth aspect of the present invention, in the cartridge according to any one of the first to tenth aspects, the cartridge includes a pair of the developing device and the photosensitive member, and the developing device and the photosensitive member are included in the cartridge. It is characterized by being held together.

  According to a thirteenth aspect of the present invention, in the main body casing, a plurality of sets of developing devices and photosensitive members are provided in parallel, and visible on each of the photosensitive members by a developer supplied from the developing devices. In the tandem type image forming apparatus configured to form an image and transfer the visible image to a recording medium, the image forming unit is provided so as to be drawable with respect to the main body casing. A frame that is attachable to and detachable from the casing; and a plurality of cartridges that include one of the developing units and that are detachably held by the frame, and the removal direction of the cartridge with respect to the frame is pulled out. It is characterized by being inclined toward the direction.

  The invention of claim 14 is characterized in that, in the invention of claim 13, there is provided a grip portion for hand grip when attaching and detaching.

  According to a fifteenth aspect of the present invention, in the method according to the fourteenth aspect, the grip portion is provided at an end portion in the pull-out direction of the image forming unit, and the image forming unit removed from the main body casing is attached to the grip portion. Is characterized in that it can be lifted in a posture in which the end on the opposite side to the pull-out direction is on the lower side.

  A sixteenth aspect of the invention is characterized in that the cartridge according to the thirteenth to fifteenth aspects is configured separately from the photosensitive member.

  The invention of claim 17 is the cartridge according to any one of claims 13 to 15, wherein the cartridge includes a pair of the developing device and the photosensitive member, and the developing device and the photosensitive member are included in the cartridge. It is characterized by being held together.

<Invention of Claim 1>
Since the direction in which the cartridge is detached from the frame is inclined toward the pull-out direction, the cartridge can be easily replaced when being pulled out.

<Invention of Claim 2>
Since the image forming unit can be attached to and detached from the main body casing, maintenance work such as jam processing in the main body casing and parts replacement can be easily performed by removing the image forming unit from the main body casing.

<Invention of Claim 3 and Claim 14>
Since the image forming unit is provided with a grip portion for hand grip when attaching and detaching, the image forming unit alone can be easily carried.

<Invention of Claim 4 and Claim 15>
Since the image forming unit detached from the main body casing can be lifted in such a posture that the grip portion is on the upper side and the end opposite to the pulling direction is on the lower side, it is easy to carry. Further, since the cartridge detachment direction is inclined toward the pull-out direction (upper side), the cartridge is unlikely to drop from the frame when being carried.

<Invention of Claim 5>
The optical path of light from the exposure means to each photoconductor is substantially parallel to the attaching / detaching direction of each cartridge. Here, since the developing unit needs to have a shape that does not block the optical path of light, when the optical path of the light intersects with the mounting / demounting direction of the cartridge, the capacity of the developing unit cannot be made very large. On the other hand, the capacity of the developing device can be maximized by making the optical path of light substantially parallel to the mounting / removal direction of the cartridge as in this configuration.

<Invention of Claim 6>
Since the cartridge attaching / detaching direction is inclined with respect to the vertical direction, the cartridge can be easily replaced. In addition, since the developing unit needs to have a shape that does not block the optical path of the light, the capacity of the developing unit cannot be made very large when the optical path of the light intersects with the mounting / demounting direction of the cartridge. As described above, the capacity of the developing device can be maximized by making the optical path of the light substantially parallel to the mounting / demounting direction of the cartridge.

<Invention of Claim 7>
Since each photoconductive drum is separated from the transfer belt when the image forming unit is pulled out, operations such as jam processing and transfer belt replacement are easy.

<Invention of Claim 8>
Since the drawing direction of the image forming unit is the same as the drawing direction of the supply tray, it is easy to handle.

<Invention of Claim 9>
Since the supply tray, the transfer belt, the image forming unit, and the discharge tray are stacked in order from the lower part to the upper part of the main body casing, the apparatus can be configured compactly.

<Invention of Claim 10>
The image forming unit is configured to be pulled out upward with respect to the main body casing, and since the cartridge detaching direction is inclined toward the pulling direction (upper side), the cartridge does not fall from the frame when being pulled out.

<Invention of Claims 11 and 16>
Since the cartridge is configured separately from the photosensitive member, only the developing device can be replaced when the developing device reaches the replacement time.

<Invention of Claims 12 and 17>
Since the cartridge includes a set of the developing device and the photosensitive member, both the developing device and the photosensitive member can be replaced at a time.

<Invention of Claim 13>
Since the removal direction of the cartridge from the frame is inclined toward the pull-out direction, workability at the time of cartridge replacement is good. Since the image forming unit can be attached to and detached from the main body casing, maintenance work such as jam processing in the main body casing and parts replacement can be easily performed by removing the image forming unit from the main body casing.

<First Embodiment>
Next, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a side sectional view showing a schematic configuration of a laser printer 1 as an image forming apparatus of the present embodiment. The laser printer 1 is a so-called direct tandem type color laser printer including four photosensitive drums 30 corresponding to black, cyan, magenta, and yellow colors. The laser printer 1 includes a main body casing 2 in which a paper feed unit 4 for feeding paper 3 as a recording medium, an image forming unit 20 and an image forming unit for forming an image on the fed paper 3 are provided. In contrast, a paper transport unit 35 for transporting the paper 3 is provided. In the following description, the right side in FIG.

  A front cover 6 that can be opened and closed is provided on the front surface of the main casing 2. The front cover 6 is opened from the closed position (see FIG. 1) that covers the front surface of the main casing 2 in a substantially vertical posture, and the upper end side is tilted forward with the lower end portion as the center to open the horizontal position (see FIG. 1). 2). By setting the front cover 6 to the open position, an image forming unit 20 (described later) accommodated in the main body casing 2 can be pulled forward. When the front cover 6 is in the closed position, the upper end thereof substantially coincides with the upper end of the main casing 2.

  The paper feed unit 4 includes a paper feed tray 7 as a supply tray that is detachably mounted on the bottom of the main casing 2, and a paper feed roller 8 and a separation pad 9 provided above the front end of the paper feed tray 7. A pickup roller 10 provided on the rear side of the paper feed roller 8, a pair of paper dust removing rollers 11 disposed above the front side of the paper feed roller 8, and a pair of resists provided above the paper dust removing roller 11 And rollers 12A and 12B.

  The paper feed tray 7 has a thin dish shape, and the paper 3 for forming an image can be stacked therein. The front wall 13 provided at the front end portion of the paper feed tray 7 is disposed below the front cover 6 on the front surface of the main body casing 2, and the paper feed tray 7 is pulled by pulling the front wall 13 forward. The main casing 2 can be pulled out horizontally to the front. A sheet pressing plate 7A on which sheets 3 can be stacked is provided on the bottom surface of the sheet feeding tray 7. The sheet pressing plate 7A is rotatably supported at the rear end portion and is illustrated in the figure. The front end is urged upward by a spring that does not. As a result, the sheets 3 stacked in the sheet feed tray 7 are in a state where the front end side is urged upward.

  The uppermost sheet 3 of the sheet feeding tray 7 is pressed toward the pickup roller 10 by the urging force of the sheet pressing plate 7A, and is directed between the sheet feeding roller 8 and the separation pad 9 by the rotation of the pickup roller 10. The transport is started. Then, the sheet 3 is turned and fed one by one when sandwiched between the sheet feeding roller 8 and the separation pad 9 by the rotation of the sheet feeding roller 8. The fed paper sheet is transported to the registration rollers 12A and 12B after the paper dust is removed by the paper dust removing roller 11.

  The registration rollers 12A and 12B are composed of a driving roller 12A and a driven roller 12B, and after the sheet 3 is registered, the sheet 3 is conveyed onto a transfer belt (sheet conveying belt) 38 of a sheet conveying unit 35 to be described later via the sheet feeding path 14. . The paper feed path 14 is a conveyance path of the paper 3 curved in an arc shape, and is formed in a frame 21 of the image forming unit 20 described later.

  A scanner unit 18 as an exposure unit is provided at the top of the main casing 2. The scanner unit 18 irradiates laser light L (corresponding to “light” in the present invention) for each color based on predetermined image data onto the surface of a corresponding photosensitive drum 30 (described later) by high-speed scanning. . Four laser beams L corresponding to the respective colors are emitted obliquely rearward and downward from the bottom surface of the scanner unit 18. The optical paths of the laser beams L are arranged at regular intervals in the front and rear directions and are parallel to each other.

  In the main casing 2, a unit accommodating portion 19 is provided below the scanner portion 18, and an detachable image forming unit 20 is accommodated therein. The image forming unit 20 includes a frame 21. The frame 21 includes a photosensitive drum 30 as an image carrier, a scorotron charger 31 as a charging unit, a developing cartridge 22 as a developing device, and a cleaning brush. Four sets of process means consisting of 33 are held in parallel in the front-rear direction (that is, the drawing direction).

  Each of the four developing cartridges 22 is detachably attached to the frame 21 and corresponds to each color of black, cyan, magenta, and yellow. The developing cartridge 22 includes a box-shaped storage case 23 whose lower side is opened, and a toner storage chamber 24 filled with toner of each color is formed in the upper portion of the storage case 23. An agitator (not shown) is provided in the toner storage chamber 24, and the agitator is rotationally driven by power input from a motor (not shown) to stir the internal toner. A supply roller 25, a developing roller 26, and a layer thickness regulating blade 27 are provided below the toner storage chamber 24.

  The supply roller 25 is rotatably supported by the housing case 23 of the developing cartridge 22, and is configured by covering a metal roller shaft with a roller made of a conductive foam material. The supply roller 25 is rotationally driven by the input of power from a motor (not shown).

  The developing roller 26 is rotatably supported in the housing case 23 of the developing cartridge 22 in a state where the developing roller 26 is in contact with the supplying roller 25 so as to be compressed with respect to the lower rear side of the supplying roller 25. The developing roller 26 is opposed to and contacts the photosensitive drum 30 in a state where the developing cartridge 22 is mounted on the frame 21. The developing roller 26 is configured by covering a metal roller shaft 26A with a roller 26B made of a conductive rubber material. In the roller 26B of the developing roller 26, the surface of a roller body made of conductive urethane rubber or silicone rubber containing carbon fine particles is coated with a urethane rubber or silicone rubber coating layer containing fluorine. A developing bias is applied to the developing roller 26 during development. The developing roller 26 is rotationally driven by the input of power from a motor (not shown).

  The layer thickness regulating blade 27 includes a pressing portion having a semicircular cross section made of insulating silicone rubber at the tip of a blade body made of a metal leaf spring material. The layer thickness regulating blade 27 is supported by the housing case 23 above the developing roller 26, and the pressing portion is pressed onto the developing roller 26 by the elastic force of the blade body.

  The toner discharged from the toner storage chamber 24 is supplied to the developing roller 26 by the rotation of the supply roller 25, and at this time, the toner is positively frictionally charged between the supply roller 25 and the developing roller 26. The toner supplied onto the developing roller 26 enters between the pressing portion of the layer thickness regulating blade 27 and the developing roller 26 as the developing roller 26 rotates, and forms a thin layer with a constant thickness on the developing roller 26. It is carried on.

  The photosensitive drum 30 has a cylindrical shape, and a drum body 30A formed by a positively chargeable photosensitive layer whose outermost layer is made of polycarbonate or the like, and an axial center of the drum body 30A along the longitudinal direction of the drum body 30A. And a metal drum shaft 30B extending in the direction. The photosensitive drum 30 is rotatably provided around the drum shaft 30B by supporting the drum shaft 30B on the frame 21. The photosensitive drum 30 is rotationally driven by input of power from a motor (not shown).

The scorotron charger 31 is disposed opposite to the photosensitive drum 30 at a predetermined interval so as not to come into contact with the photosensitive drum 30 at an obliquely upper rear side of the photosensitive drum 30. The scorotron charger 31 uniformly charges the surface of the photosensitive drum 30 to positive polarity by generating corona discharge from a charging wire such as tungsten.
The cleaning brush 33 is disposed on the rear side of the photosensitive drum 30 so as to face and contact the photosensitive drum 30.
A part of the configuration of the image forming unit 20 will be described later in detail.

  The paper transport unit 35 is disposed below the image forming unit 20 mounted in the unit storage unit 19. The paper transport unit 35 includes a pair of belt support rollers 36 and 37 provided in parallel with each other at the rear side and the front side, and a transfer belt 38 spanned between the rollers 36 and 37. The transfer belt 38 circulates and moves as the rear belt support roller 36 is driven to rotate by the power of the motor. Inside the transfer belt 38, four transfer rollers 39 arranged to face the respective photosensitive drums 30 of the image forming unit 20 described above are arranged at regular intervals in the front-rear direction, and correspond to the respective photosensitive drums 30. A transfer belt 38 is sandwiched between the transfer roller 39 and the transfer roller 39. A cleaning roller 40 for cleaning residual toner attached on the transfer belt 38 is provided below the transfer belt 38. The paper 3 sent out from the registration roller 12 passes through the paper feed path 14 and comes into contact with the vicinity of the front end of the upper surface of the transfer belt 38, where it is electrostatically attracted to the upper surface of the transfer belt 38 and circulates in the transfer belt 38. As it moves, it is transported backward (laterally).

  As the surface of the photosensitive drum 30 rotates, the surface of the photosensitive drum 30 is first uniformly charged positively by the scorotron charger 31 and then exposed by high-speed scanning of the laser light L from the scanner unit 18 to form on the paper 3. An electrostatic latent image corresponding to the image to be formed is formed.

  Next, when the developing roller 26 rotates, the positively charged toner carried on the developing roller 26 is formed on the surface of the photoconductive drum 30 when it comes into contact with the photoconductive drum 30. An electrostatic latent image, that is, an exposed portion of the surface of the photosensitive drum 30 that is uniformly positively charged is exposed to the laser beam L and the potential is lowered. As a result, the electrostatic latent image on the photosensitive drum 30 is visualized, and a toner image by reversal development is carried on the surface of the photosensitive drum 30.

  Thereafter, the toner image carried on the surface of the photosensitive drum 30 is transferred to the transfer roller 39 while the sheet 3 conveyed by the transfer belt 38 passes through the transfer position between the photosensitive drum 30 and the transfer roller 39. Is transferred to the sheet 3 by the transfer bias applied to the sheet 3. The sheet 3 on which the toner image is transferred is then conveyed to the fixing device 42.

  The fixing device 42 is disposed behind the paper transport unit 35 in the main body casing 2. The fixing device 42 includes a heating roller 43, a pressure roller 44, and the like disposed so as to face each other, and heat-fixes the toner image transferred onto the paper 3 onto the paper surface. Then, the heat-fixed sheet 3 is conveyed to a discharge roller 46 provided on the upper portion of the main body casing 2 by a conveyance roller 45 disposed obliquely above and behind the fixing device 42. On the upper surface of the main casing 2, there is provided a paper discharge tray 47 as a discharge tray that is substantially horizontal at the front end side and inclined rearward at the rear end side. They are stacked on the paper discharge tray 47.

  Next, the configuration of the image forming unit 20 will be described in more detail. The frame 21 has a long and narrow box shape in the front and rear, and four partition walls 50 and 51 are provided at equal intervals in the front and rear direction behind the front wall 49 provided at the front end thereof. Between the partition walls 50 and 51 and the partition wall 50 or the front wall 49 located on the front side thereof, a cartridge mounting portion 54 opened upward is provided, and the above-described developing cartridge 22 is detachably mounted on each of the partition walls 50 and 51. It has come to be. Of the partition walls 50 and 51, the three partition walls 50 excluding the rear-end partition wall 51 are approximately two-thirds the height of the frame 21, and are therefore provided on both sides of the partition wall 50. The cartridge mounting portions 54 are in communication with each other at the upper part of the frame 21. Further, the front surfaces 50A and 51A of the partition walls 50 and 51 are slightly inclined downward toward the front side toward the upper end side, and the inclination angle of the laser beams L emitted from the scanner unit 18 described above. Is almost parallel to the optical path.

  The photosensitive drum 30 is held on the bottom of each cartridge mounting portion 54 at a position near the rear partition walls 50 and 51, respectively. The lower end portion of each photoconductive drum 30 protrudes slightly below the bottom surface 21A of the frame 21 and is disposed opposite to the transfer roller 39 with the transfer belt 38 interposed therebetween as described above. Further, the scorotron charger 31 and the cleaning brush 33 described above are arranged around the respective photosensitive drums 30 at the inner lower portions of the partition walls 50 and 51.

  The housing cases 23 of the developing cartridges 22 have the same shape, and the upper portion of the housing case 23 is larger than the lower portion in the front-rear direction, following the shape of the cartridge mounting portion 54. Further, the upper end portion of each housing case 23 projects to a predetermined height above the upper end of the frame 21. Further, the front surface 23A of each storage case 23 is substantially parallel to the front surfaces 50A and 51A of the partition walls 50 and 51, and the front surface 23A of the rear three storage cases 23 is substantially the same as the front surface 50A of the partition wall 50. Arranged side by side on the line. Further, the rear surface 23B of each storage case 23 is parallel to the front surface 23A of the storage case 23 (that is, parallel to the optical path of the laser beam L), and the front surface 23A of the storage case 23 or the partition wall 51 disposed on the rear side, respectively. The front surfaces 51A are opposed to each other with a predetermined interval. The laser beam L emitted from the scanner unit 18 is a slit formed between the rear surface 23B of each storage case 23 and the front surface of the storage case 23 or the front surface 51A of the partition wall 51 disposed on the rear side. Passing through the gaps on the surface, the photosensitive drum 30 is reached.

  Further, on both the left and right side walls 21 </ b> B of the frame 21, guide grooves 57 through which the end portions of the roller shaft 26 </ b> A of the developing roller 26 are inserted are provided corresponding to the developing cartridges 22. The guide groove 57 extends obliquely forward and upward from the lower portion of the side wall 21B, and opens at the upper end of the side wall 21B. At the time of attaching / detaching the developing cartridge 22, the attaching / detaching operation of the developing cartridge 22 is guided by moving the roller shaft 26A along the guide groove 57. In other words, the direction in which the developing cartridge 22 is detached is inclined toward the front side (the direction in which the frame 21 is pulled out) with respect to the vertical axis. Further, the attaching / detaching direction of each developing cartridge 22 is made substantially parallel to the optical path of the laser light L from the scanner unit 18.

  Further, the frame 21 is provided with a locking means (not shown) for holding each developing cartridge 22 in a regular position, and the developing cartridge 22 is inserted from the outside to a regular position in the cartridge mounting portion 54. Then, this locking means is elastically locked to the developing cartridge 22, and when the developing cartridge 22 is pulled out from the normal position, the locking is released.

  At the front end of the lower end portion of the front wall 49 in the frame 21, an overhang portion 52 that projects downward from the bottom surface 21 </ b> A of the frame 21 is formed over the entire width. The driven roller 12B of the pair of registration rollers 12A and 12B described above is held on the rear surface of the protruding portion 52. Further, a pair of upper and lower guides 14A and 14B are integrally provided at the lower portion of the overhanging portion 52, and a paper feed path 14 that is curved in an approximately arc shape is formed between the guides 14A and 14B. The paper 3 sent out from the registration rollers 12A and 12B passes through the paper feed path 14 while being guided by the guides 14A and 14B, and is supplied onto the transfer belt 38. A pair of rear leg portions 53 are provided at the rear end of the lower end of the left and right side walls 21 </ b> B of the frame 21 so as to protrude downward from the bottom surface 21 </ b> A of the frame 21. When the image forming unit 20 is placed on a flat placement surface T (see FIG. 4) such as a desk, the bottom leg 21A of the frame 21 is brought into contact with the rear leg portion 53 and the projecting portion 52. Is maintained at a position separated from the plane, whereby the photosensitive drum 30 is held at a height position that does not interfere with the plane.

  Rail-shaped guide means (not shown) is provided between the image forming unit 20 and the main body casing 2, and the image forming unit 20 can slide in the front-rear direction according to the guide means. The left and right side walls 21B of the frame 21 are respectively provided with a protruding protrusion 55 protruding upward from the rear end of the upper edge. On the other hand, on the inner side wall of the unit housing portion 19 in the main body casing 2, a removal restricting portion 56 that can be locked with the removal preventing projection 55 is provided so as to protrude downward toward the front end. When the image forming unit 20 is pulled out from the normal mounting position shown in FIG. 1 to the drawing stop position shown in FIG. 2, the removal preventing projection 55 abuts against the rear surface of the removal restricting portion 56 and the removal of the image forming unit 20 is restricted. At this pull-out stop position, the front end side of the frame 21 is slightly lowered from the rear end side due to its own weight, and the rear-end-side protruding protrusion 55 and the removal restricting portion 56 are maintained in the engaged state. Further, at the drawing stop position, the direction of disengagement (upward) of each developing cartridge 22 mounted on the frame 21 is opened, and it becomes a detachable state. Further, the front wall 49 of the frame 21 is provided with a gripping portion 58 projecting forward, and this gripping portion 58 can be used for hand grip when pulling out and for hand grip when attaching and detaching. It can be done. In the above-described pull-out stop position, the front end portions (the gripping portion 58 and the overhang portion 52) of the frame 21 protrude from the front end of the front cover 6 in the open position.

In the laser printer 1 configured as described above, when pulling out the image forming unit 20 from the state shown in FIG. 1, first, the front cover 6 is opened, the gripping portion 58 is gripped, and the image forming unit 20 is pulled out to the front side. .
When the image forming unit 20 reaches the drawing stop position, as shown in FIG. 2, the retaining protrusion 55 comes into contact with the removal restricting portion 56, and the image forming unit 20 stops and is prevented from coming out of the main body casing 2. The Thus, the developing cartridges 22 can be replaced by pulling out the image forming unit 20 to the pulling-out stop position. Here, the developer cartridge 22 is detached by pulling it diagonally forward and upward with respect to the frame 21, and on the other hand, it is mounted by pushing it diagonally downward. Good workability. Since the paper feed path 14 is formed in the frame 21, when the paper 3 is jammed while passing through the paper feed path 14, the frame 21 is pulled out and the paper 3 is pulled out to the front side. Therefore, the jam processing becomes easy. Furthermore, since the substantially front half of the paper feed path 14 projects forward from the front end of the front cover 6 at the drawer stop position, the paper 3 pulled out while being caught by the paper feed path 14 is easily removed. be able to.

  Subsequently, when the image forming unit 20 is removed from the main casing 2, the front end of the frame 21 is lifted slightly from the state shown by the solid line in FIG. (See the chain line in FIG. 2). Then, since the retaining protrusion 55 is separated obliquely downward and rearward from the slip-out restricting portion 56, the locking is released, so that the frame 21 is moved to the front side while keeping the inclined posture, so that the frame 21 is moved to the main body casing 2. Can be removed from. At the drawing stop position, the gripping portion 58 projects forward from the front end of the opened front cover 6, so that the gripping portion 58 can be easily gripped and the image forming unit 20 can be easily removed.

  Thus, the image forming unit 20 removed from the main body casing 2 can be lifted in a vertical posture with the gripping portion 58 as the upper side and the end portion (rear end portion) opposite to the pulling direction as the lower side. (Refer to FIG. 3, where an arrow G indicates a downward direction). As described above, since the grip portion 58 is used in common during the pulling-out and lifting, a series of operations from the pulling-out operation to the lifting operation can be smoothly performed without changing hands around. Further, in the lifting posture of FIG. 3, the direction in which the developing cartridge 22 is detached from the frame 21 is inclined upward, so that even if a slight impact is applied to the image forming unit 20, the developing cartridge 22. Will not fall off the frame 21 by mistake.

  In this way, the image forming unit 20 can be carried away from the main casing 2. When the image forming unit 20 is placed on a flat placement surface T such as a desk with the bottom surface 21A side down, the rear leg 53 and the overhanging portion 52 are placed on the placement surface T as shown in FIG. The photosensitive drums 30 are held at positions separated from the placement surface T. Thereby, since the interference between the photosensitive drum 30 and the mounting surface T is avoided, work such as replacement of parts can be performed without worrying about damaging the photosensitive drum 30 due to interference with other members. Can do. Thus, when the image forming unit 20 is removed from the main casing 2, the front surface of the main casing 2 is opened. Therefore, as shown in FIG. 4, processing of the paper 3 causing a jam in the main casing 2, replacement of parts, and the like. Maintenance work can be performed. In particular, in the present embodiment, the image forming unit 20 including the photosensitive drum 30 and the transfer belt 38 that conveys the paper 3 are separated from each other, so that the jam processing and the replacement operation of the transfer belt 38 can be easily performed. Note that when the photosensitive drum 30 of the image forming unit 20 is replaced, the entire frame 21 may be replaced.

  As described above, according to this embodiment, the direction in which the developing cartridge 22 is detached from the frame 21 is inclined toward the pull-out direction, so that the developing cartridge 22 can be easily replaced.

  Further, since the image forming unit 20 can be attached to and detached from the main body casing 2, the maintenance work such as jam processing and replacement of parts in the main body casing 2 can be easily performed by removing the image forming unit 20 from the main body casing 2. be able to.

  In addition, since the image forming unit 20 is provided with a grip portion 58A for hand grip when attaching and detaching, the image forming unit 20 alone can be easily carried.

  The image forming unit 20 removed from the main body casing 2 can be lifted in such a posture that the gripping portion 58 is on the upper side and the end opposite to the pulling direction is on the lower side, so that it is easy to carry. Further, since the direction in which the developing cartridge 22 is detached is inclined toward the pull-out direction (upper side), the developing cartridge 22 is unlikely to drop from the frame 21 when being carried.

  Further, the optical path of the laser light L from the scanner unit 18 to each photosensitive drum 30 is substantially parallel to the attaching / detaching direction of each developing cartridge 22 as a developing device. Here, since it is necessary for the developing cartridge 22 to have a shape that does not block the optical path of the laser light L, when the optical path of the laser light L intersects with the mounting / demounting direction of the cartridge, the capacity cannot be made very large. On the other hand, the capacity of the developing cartridge 22 can be maximized by making the optical path of the laser light L substantially parallel to the attaching / detaching direction of the developing cartridge 22 as in this configuration.

  Further, since each photosensitive drum 30 is separated from the transfer belt 38 when the image forming unit 20 is pulled out, operations such as jam processing and replacement of the transfer belt 38 are easy.

  Further, since the drawing direction of the image forming unit 20 is the same as the drawing direction of the paper feed tray 7, it is easy to handle.

  Further, since the paper feed tray 7, the transfer belt 38, the image forming unit 20, and the paper discharge tray 47 are stacked in order from the lower part to the upper part of the main body casing 2, the apparatus can be configured compactly.

  Further, since the developing cartridge 22 as a developing device is configured separately from the photosensitive drum 30, only the developing device can be replaced when the developing device reaches the replacement time.

FIG. 5 shows a modification of the first embodiment.
In the first embodiment, the developing cartridge 22 as the developing device is shown to be detachable from the frame 21. However, in the image forming unit 70A of this modified example, four detachable from the frame 75 are provided. The cartridge 76 includes a developing cartridge 77 as a developing device and a photosensitive drum 30 as a set. The cartridge 76 includes a cartridge frame 78 that holds the photosensitive drum 30 at the lower end. Further, a developing cartridge 77 is detachably supported on the cartridge frame 78, and the photosensitive drum 30 and the developing roller 26 of the developing cartridge 77 are held in pressure contact with each other. In addition, a slit 80 is formed between the rear surface of the housing case 79 in the developing cartridge 77 and the cartridge frame 78 so as to continue from the upper end of the cartridge 76 to the upper surface of the photosensitive drum 30. The laser light L emitted from the scanner unit 18 on the side can pass therethrough.

  The frame 75 is provided with four partition walls 83 arranged at equal intervals in the front-rear direction behind the front wall 82. A cartridge mounting portion 84 opened upward is provided between each partition wall 83 and the partition wall 83 or the front wall 82 located on the front side thereof, and the above-described cartridge 76 is detachably mounted on each. Of the partition walls 83, the front three partition walls 83 are smaller in height than the frame 75, and the cartridge mounting portions 84 communicate with each other at the top. In addition, a scorotron charger 31 and a cleaning brush 33 are disposed around the photosensitive drum 30 below each partition wall 83. Further, guide grooves 85 through which the drum shaft 30B of the photosensitive drum 30 is inserted are provided on the left and right side walls 75A of the frame 75. The guide groove 85 extends obliquely forward and upward from the lower portion of the side wall 75A, and opens at the upper end of the side wall 75A. When the cartridge 76 is attached or detached, the attachment or detachment of the cartridge 76 is guided by moving the drum shaft 30B along the guide groove 85. That is, the direction in which the cartridge 76 is detached is inclined obliquely toward the front side (the direction in which the frame 75 is pulled out). Further, the mounting / removal direction of the cartridge 76 is substantially parallel to the extending direction of the slit 80 and the optical path of the laser light L from the scanner unit 18.

  According to this modification, since the cartridge 76 includes a pair of the developing cartridge 77 and the photosensitive drum 30, both the developing cartridge 77 as the developing device and the photosensitive drum 30 are exchanged at a time. be able to.

  FIG. 6 shows another modification of the first embodiment described above. In the image forming unit 70B of this modification, four cartridges 88 that can be attached to and detached from the frame 87 are a set of a developing cartridge 89, a photosensitive drum 30, a scorotron charger 31, and a process unit, respectively. A cleaning brush 33 is provided. The cartridge 88 also includes a cartridge frame 90 that holds the photosensitive drum 30 at the lower end. A scorotron charger 31 and a cleaning brush 33 are further held around the photosensitive drum 30 below the cartridge frame 90. The developing cartridge 89 is detachably supported on the cartridge frame 90, and the photosensitive drum 30 and the developing roller 26 of the developing cartridge 89 are held in pressure contact with each other. In addition, a slit 92 is formed between the rear surface of the housing case 91 and the cartridge frame 90 in the developing cartridge 89 so as to continue from the upper end of the cartridge 88 to the upper surface of the photosensitive drum 30. The laser light L emitted from the scanner unit 18 on the side can pass therethrough.

  The frame 87 is provided with four cartridge mounting portions 93 on which cartridges 88 are detachably mounted, arranged in the front and rear directions so as to communicate with each other. Further, guide grooves 94 through which the drum shaft 30B of the photosensitive drum 30 is inserted are provided on the left and right side walls 87A of the frame 87. The guide groove 94 extends obliquely forward and upward from the lower portion of the side wall 87A and opens at the upper end of the side wall 87A. When the cartridge 88 is attached or detached, the attachment or detachment of the cartridge 88 is guided by moving the drum shaft 30B along the guide groove 94. That is, the removal direction of the cartridge 88 is inclined obliquely toward the front side (the drawing direction of the frame 87). Further, the attaching / detaching direction of each cartridge 88 is substantially parallel to the extending direction of the slit 92 and the optical path of the laser light L from the scanner unit 18.

  According to this modification, a set of the developing cartridge 89, the photosensitive drum 30, the scorotron charger 31, and the cleaning brush 33 constituting the process means can be replaced at a time.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIGS. In the following description, the right side in FIGS. Since most of the configuration of the present embodiment is the same as that of the first embodiment, portions having the same functions as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The image forming apparatus 1A according to the present embodiment includes an image forming unit 60 attached to the inside of the main casing 2A (cannot be pulled out). In the image forming unit 60, the attaching / detaching direction of the developing cartridge 22 with respect to the frame 21 is inclined obliquely forward with respect to the vertical axis, and the attaching / detaching direction is substantially parallel to the optical path of the laser light L from the scanner unit 18. It has become. An upper surface cover 61 that can be opened and closed is provided on the upper surface of the main casing 2 so as to cover the upper part of the image forming unit 60. The upper surface cover 61 is rotatable around an attachment shaft 62 provided along the left-right direction on the rear side of the main body casing 2A, and closes the upper surface of the main body casing 2 in a horizontal posture as shown in FIG. As shown in FIG. 8, it is possible to displace from the position to the open position where the front end rises in an inclined posture. The scanner unit 18 is held inside the upper surface cover 61, and the upper portion of the image forming unit 60 is opened by setting the upper surface cover 61 to the open position, and each developing cartridge 22 is attached and detached through the opening 63 thus formed. It becomes possible.

  In the present embodiment, since the mounting direction of the developing cartridge 22 is inclined with respect to the vertical axis, the developing cartridge 22 in the main casing 2A can be easily replaced from the periphery of the main casing 2A. In particular, since the attaching / detaching direction of the developing cartridge 22 is inclined obliquely forward, the upper surface cover 61 in the open position does not get in the way, and replacement work can be performed more easily.

<Third Embodiment>
Next, a third embodiment of the present invention will be described with reference to FIGS. In the following description, the right side in FIGS. The procedure for forming an image is the same as that in the first embodiment, and a detailed description thereof will be omitted.
FIG. 13 is a side sectional view showing a schematic configuration of a laser printer 100 as an image forming apparatus of the present embodiment. The laser printer 100 is a so-called direct tandem type color laser printer including four photosensitive drums 101 corresponding to black, cyan, magenta, and yellow colors.

  The laser printer 100 includes a vertically long main body casing 102, and a unit housing portion 104 in which the image forming unit 103 is mounted is provided inside the main body casing 102. In addition, a sheet feeding tray 106 on which sheets 105 serving as recording media are stacked is provided below the main body casing 102, and the sheets 105 are supplied to the transfer belt 107 from here. The transfer belt 107 is disposed so as to extend in a substantially vertical direction on the rear side of the unit accommodating portion 104, and conveys the sheet 105 electrostatically attracted to the surface thereof to the upper fixing device 108. A transfer roller (not shown) is provided inside the transfer belt 107 so as to be opposed to the respective photosensitive drums 101 of the image forming unit 103. The sheet 105 that has passed through the fixing unit 108 is conveyed to a sheet discharge roller 109. A top cover 110 that can be opened and closed is provided at the top of the main body casing 102, and a fixing device 108 and a paper discharge roller 109 are integrally held inside the top cover 110. A paper discharge tray 111 for stacking the paper 105 discharged from the paper discharge rollers 109 is formed from the upper surface of the upper cover 110 to the upper surface of the main body casing 102. In the main body casing 102, a scanner unit 112 as an exposure unit is provided on the front side of the unit housing unit 104, and four laser beams L corresponding to the respective colors are emitted obliquely rearward and downward from the rear surface. Is done. The optical paths of the laser beams L are arranged at regular intervals in the vertical direction and are parallel to each other.

  The image forming unit 103 can be pulled upward and detachable with respect to the main body casing 102. Between the image forming unit 103 and the main body casing 102, guide means (not shown) guides the pulling operation. And locking means (not shown) for holding the image forming unit 103 in the drawing stop position. The image forming unit 103 includes a vertically long substantially box-shaped frame 113. On the upper surface of the frame 113, there is provided a grip portion 114 that can be grasped by hand when being pulled out or attached and detached. At the rear part of the frame 113, four photosensitive drums 101 are vertically arranged at regular intervals, and a scorotron charger 115 and a cleaning brush 116 are provided around each photosensitive drum 101, respectively.

  On the front side of the photosensitive drum 101, a cartridge mounting portion 117 that is open forward is formed. Here, four developing cartridges 118 corresponding to the respective colors are mounted in a state of being arranged in the vertical direction and separated from each other. . The developing cartridge 118 includes a developing roller 120 at the rear end portion of the housing case 119, and both end portions of the roller shaft 120 </ b> A provided in the developing roller 120 protrude from the left and right sides of the housing case 119. In addition, guide pins 121 are provided on the left and right outer surfaces of the housing case 119 so as to protrude obliquely forward and upward with respect to the roller shaft 120A. On the other hand, on both left and right side walls 113A of the frame 113, guide grooves 122 are formed in which the roller shafts 120A and the guide pins 121 of the developing cartridges 118 are engaged. The guide groove 122 extends obliquely forward and upward from the front portion of the side wall 113A and opens at the front end of the side wall 113A. By engaging the roller shaft 120 </ b> A and the guide pin 121 with the guide groove 122, the posture of the developing cartridge 118 is determined, and by moving the roller shaft 120 </ b> A and the guide pin 121 along the guide groove 122, Detachment is guided. In other words, in this embodiment, the direction in which the developing cartridge 118 is detached is inclined obliquely upward (the direction in which the frame 113 is pulled out). In addition, the attaching / detaching direction of each developing cartridge 118 is substantially parallel to the optical path of the laser light L from the scanner unit 112. Further, the upper and lower surfaces of the housing case 119 in each developing cartridge 118 are formed so as to be substantially parallel to the optical path of the laser light L.

  When pulling out the image forming unit 103 from the normal mounting position shown in FIG. 9, first, the upper surface cover 110 is opened, and the image forming unit 103 is pulled upward by grasping the grip portion 114 in the unit housing portion 104 (see FIG. 10). ). When the image forming unit 103 is pulled out to the pull-out stop position, the frame 113 is held by the locking means described above, and each developing cartridge 118 can be replaced. Here, the developing cartridge 118 is detached by pulling it obliquely upward to the upper side (drawing direction of the image forming unit 103), and on the contrary, it is attached by pushing it obliquely to the lower rear side. Compared with, the workability of replacement work is better.

  Subsequently, when the image forming unit 103 is removed from the main body casing 102, the above-described locking unit is released, and the image forming unit 103 is lifted by holding the grip portion 114. As described above, since the image forming unit 103 is provided with the grip portion 114 for gripping when attaching and detaching, the image forming unit 103 can be easily carried by itself. Further, when the image forming unit 103 is pulled out and lifted, the separation direction of each developing cartridge 118 is obliquely upward, so that the developing cartridge 118 may be mistaken even when an impact is applied to the frame 113, for example. It will not fall off the frame 113. In addition, by making the optical path of the laser light L substantially parallel to the attaching / detaching direction of the developing cartridge 118, the capacity of the developing cartridge 118 can be maximized. Furthermore, since the image forming unit 103 can be attached to and detached from the main body casing 102, the image forming unit 103 is removed from the main body casing 102, so that maintenance work such as jam processing and component replacement in the main body casing 102 is easily performed. be able to.

  As described above, according to the present embodiment, the image forming unit 103 is configured to be drawn upward with respect to the main body casing 102, and the detaching direction of the developing cartridge 118 is inclined toward the drawing direction (upward). Therefore, the developing cartridge 118 does not fall from the frame 113 when pulled out.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

(1) In each of the above embodiments, a direct tandem system that performs direct transfer to a recording medium is exemplified, but the present invention is directed to the recording medium via an intermediate transfer member (intermediate transfer belt or intermediate transfer drum). The present invention can also be applied to an intermediate transfer type color laser printer that performs transfer.
(2) As a recording medium on which an image is recorded, an OHP plastic sheet or a cloth medium may be used in addition to paper.
(3) In the first embodiment, the grip portion is provided at the end of the frame in the pull-out direction. However, the grip portion for hand grip when attaching / detaching may be provided at another position, for example, on both sides of the frame. good.

(4) In the first and third embodiments, the image forming unit is drawn out in the horizontal direction and the vertical direction with respect to the main body casing. However, according to the present invention, the image forming unit is extracted from the main body casing. You may make it pull out diagonally upward.
(5) In each of the above embodiments, the exposure unit that performs exposure with laser light is exemplified. However, as the exposure unit, an exposure unit that uses other light, such as an LED, may be used. Further, the exposure unit may be mounted on the frame of the image forming unit so as to be pulled out integrally with the frame.

1 is a side sectional view showing a schematic configuration of a laser printer as an image forming apparatus according to a first embodiment of the present invention. Side sectional view showing a state in which the image forming unit is pulled out from the main body casing. Side sectional view showing a state where the image forming unit is lifted up alone. Side sectional view showing a state in which the image forming unit is removed from the main casing. Side sectional view showing an image forming unit in a modification of the first embodiment FIG. 5 is a side sectional view showing an image forming unit in another modification of the first embodiment. Side sectional view which shows schematic structure of the laser printer in 2nd Embodiment of this invention. Side sectional view showing the top cover of the laser printer opened The side view which shows schematic structure of the image forming unit in 3rd Embodiment. Side sectional view showing a state in which the image forming unit is pulled out from the main body casing.

Explanation of symbols

1, 1A, 100 ... Laser printer (image forming apparatus)
2, 2A, 102 ... Main body casing 3, 105 ... Paper (recording medium)
7. Paper feed tray (supply tray)
18, 112 ... Scanner unit (exposure means)
20, 70A, 70B, 103 ... image forming units 21, 75, 87, 113 ... frames 22, 118 ... developing cartridge (cartridge, developing device, process means)
30, 101 ... Photosensitive drum (photosensitive member, process means)
38, 107 ... transfer belt 47 ... paper discharge tray (discharge tray)
58, 114 ... gripping portions 76, 88 ... cartridge 77, 89 ... developing cartridge (developing device)
L ... Laser light (light)

Claims (17)

A plurality of sets of developing units and photosensitive members are provided in parallel, and a visible image is formed on each photosensitive member by the developer supplied from each developing unit, and the visible image is transferred to a recording medium. A tandem image forming apparatus configured as described above,
A main body casing, an image forming unit provided so as to be drawable with respect to the main body casing, and at least one of the developing device or the photosensitive member, and is detachably held on a frame of the image forming unit. A plurality of cartridges,
An image forming apparatus, wherein a direction in which the cartridge is detached from the frame is inclined toward a drawing direction of the image forming unit. The image forming apparatus according to claim 1, wherein the image forming unit is detachable from the main body casing. The image forming apparatus according to claim 2, wherein the image forming unit is provided with a grip portion for hand grip when attaching and detaching. The grip portion is provided at an end portion in the pull-out direction of the image forming unit, and the image forming unit removed from the main body casing has the grip portion on the upper side and an end portion opposite to the pull-out direction on the lower side. The image forming apparatus according to claim 3, wherein the image forming apparatus can be lifted in a posture. Each of the plurality of cartridges is configured to include the developing unit, and an exposure unit that irradiates light to each of the photosensitive members to form an electrostatic latent image is provided in the main body casing. , In which the developing units are arranged side by side between the exposure means and the photosensitive members,
5. The image forming apparatus according to claim 1, wherein an optical path of light from the exposure unit to each of the photoconductors is substantially parallel to an attaching / detaching direction of each of the cartridges. A plurality of sets of developing units and photosensitive members are provided in parallel, and a visible image is formed on each photosensitive member by the developer supplied from each developing unit, and the visible image is transferred to a recording medium. A tandem image forming apparatus configured as described above,
A main body casing, an exposure unit provided in the main body casing for irradiating light to each of the photoconductors to form an electrostatic latent image, and one of the developing units. A plurality of cartridges detachably provided in the main body casing so that a developing device is arranged side by side between the exposure unit and each of the photosensitive members;
The attachment / detachment direction of each cartridge is inclined with respect to the vertical direction,
An image forming apparatus, wherein an optical path of light from the exposure unit to each of the photosensitive members is substantially parallel to a direction in which each cartridge is attached or detached. A transfer belt for transferring the toner image on each photoconductor to the recording medium is provided in the main body casing. When the image forming unit is mounted, each photoconductor is positioned at a position facing the transfer belt. 7. The image forming apparatus according to claim 1, wherein each of the photosensitive members is separated from the transfer belt when the image forming unit is pulled out. 2. The main body casing is provided with a supply tray on which the recording medium is loaded so that it can be pulled out, and the drawing direction of the image forming unit is the same as the pulling direction of the supply tray. The image forming apparatus according to claim 7. A supply tray disposed at a lower portion in the main body casing and stacking a plurality of the recording media;
A transfer belt disposed above the supply tray and transporting the recording medium fed from the supply tray in a lateral direction;
An image forming unit disposed above the transfer belt and configured to transfer a toner image on each photoconductor to the recording medium by causing the photoconductor to face the recording medium conveyed on the transfer belt;
The image forming apparatus according to claim 1, further comprising: a discharge tray provided on an upper surface of the main body casing and configured to discharge the recording medium fed from the transfer belt. . The image forming apparatus according to claim 1, wherein the image forming unit is configured to be drawn upward with respect to the main body casing. The image forming apparatus according to claim 1, wherein the cartridge is configured separately from the photoconductor. 11. The cartridge according to claim 1, wherein the cartridge includes a pair of the developing device and the photosensitive member, and the developing device and the photosensitive member are integrally held with each other. The image forming apparatus described in 1. A plurality of sets of developing units and photosensitive members are provided in parallel in the main body casing, and a visible image is formed on each photosensitive member by the developer supplied from the developing units, and the visible image is recorded on the recording medium. In the tandem type image forming apparatus configured to be transferred to the image forming unit, an image forming unit provided so as to be drawable with respect to the main body casing,
A frame that is attachable to and detachable from the main body casing, and a plurality of cartridges that are configured to include one of the developing devices and that are detachably held by the frame;
An image forming unit, wherein a direction in which the cartridge is detached from the frame is inclined toward a pull-out direction. The image forming unit according to claim 13, further comprising a grip portion for hand grip when attaching and detaching. The grip portion is provided at an end portion in the pull-out direction of the image forming unit, and the image forming unit removed from the main body casing has the grip portion on the upper side and an end portion opposite to the pull-out direction on the lower side. The image forming unit according to claim 14, wherein the image forming unit can be lifted in a posture. 16. The image forming unit according to claim 13, wherein the cartridge is configured separately from the photoconductor. 16. The cartridge according to claim 13, wherein the cartridge includes a set of the developing device and the photosensitive member, and the developing device and the photosensitive member are integrally held with each other. The image forming unit described in 1.

Images