JP2006098772A - Image forming apparatus and unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate maintenance work such as jam processing and replacement of each component. <P>SOLUTION: An image forming unit 20 can be drawn out of a main body casing 2 and be attached to and detached from the main body casing 2. A turnable handle member 58 is attached to a frame 21 of an image forming unit 20, and the image forming unit 20 can be separated from the main body casing 2 and be lifted as a single body by drawing out the image forming unit 20 with the handle member 58 in a drawing position of being approximately horizontally brought down and then inclining and pulling the frame 21 to the front side with the handle member 58 in a lifting position of being stood obliquely. Thus maintenance work such as jam processing and component replacement in the main body casing 2 is facilitated. <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. As such an image forming apparatus, for example, a cover that can be opened and closed is provided on the upper surface of the main body casing, and by opening the cover, it is possible to replace parts such as a developing cartridge inside the apparatus or to perform operations such as jam processing. There is something. In addition, there is a configuration in which a drawer loaded with a developing cartridge or the like is provided, and the developing cartridge or the like can be replaced by pulling out the drawer from the main body casing to a predetermined position.

  However, when the above-described cover is provided when performing operations such as jam handling and replacement of each component, it is difficult to perform the operation because each component such as the photoconductor and the developing cartridge inside the apparatus becomes an obstacle. Even with the above-described drawers, there is a problem that it is difficult to carry out the work on the back side of the apparatus because the drawers in the state of being pulled out from the main casing are obstructive.

  The present invention has been completed based on the above-described circumstances, and provides an image forming apparatus and an image forming unit capable of facilitating maintenance work such as jam processing and replacement of each component. Objective.

  As a means for achieving the above object, in the image forming apparatus according to the first aspect of the present invention, a plurality of sets of developing units and photosensitive members are provided in parallel in the main body casing, and supplied from the developing units. A tandem type image forming apparatus configured such that a visible image is formed on each of the photoconductors by a developer, and the visible image is transferred to a recording medium. An image forming unit comprising a plurality of sets of developing units and a frame supporting the photosensitive member, and a plurality of cartridges configured to include at least one of the developing unit or the photosensitive member and detachably held on the frame. Is provided so that it can be pulled out with respect to the main casing. The image forming unit is characterized in that it can be attached to and detached from the main casing.

  According to a second aspect of the present invention, in the first aspect, the image forming unit is allowed to be pulled out to a pull-out stop position where the cartridge can be attached and detached, and from the pull-out stop position to the pull-out direction. It has a feature in that it is provided with a drop-out restricting means capable of restricting the drop-out and releasing the restriction.

  The invention of claim 3 is characterized in that in the image forming unit according to claim 1 or 2, the image forming unit is provided with a grip portion for hand grip when lifting.

  According to a fourth aspect of the present invention, in the image forming unit according to the second aspect, the image forming unit is provided with a grip portion for hand grip when lifting, and the grip portion releases the slip-off restricting means. It also has a feature in that it also serves as a release operation section for making it happen.

  The invention of claim 5 is characterized in that, in the invention described in claim 3 or claim 4, the gripping portions are provided on both sides with a central axis along the drawing direction of the frame.

  According to a sixth aspect of the present invention, the image forming unit is pulled out from the main body casing in a substantially horizontal direction according to the third or fourth aspect of the invention, and the gripping portion is provided in the image forming unit. It is characterized in that it can be displaced to a drawing position located at an end in the drawing direction and a lifting position located closer to the center of gravity in the drawing direction than the drawing position.

  According to a seventh aspect of the present invention, when the handle member having the grip portion is rotatably attached to the frame, and the grip portion is in the lifting position. A stopper that abuts on the handle member and restricts rotation of the grip portion in a direction opposite to the pull-out position is provided, and the image forming unit is lifted with the grip portion in the lift position. In some cases, a torque is applied between the frame and the handle member in a direction in which the stopper is always pressed against the handle member regardless of the mounting state of the cartridges on the frame. .

  According to an eighth aspect of the present invention, in the apparatus according to any one of the first to seventh aspects, the image forming unit is pulled out in a substantially horizontal direction from the main body casing. A handle for gripping at the time of pulling out is provided at an end in the pulling direction, and a cover is provided on the main body casing so as to be able to open and close a side surface in the pulling direction of the image forming unit. When the image forming unit is pulled out as the center of rotation, the upper end side is opened in the pulling direction, and when the image forming unit is pulled out, the handle portion is configured to protrude outward from the end portion of the open cover. It has the characteristics in the place.

  According to a ninth aspect of the present invention, in the apparatus according to any one of the first to eighth 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.

  According to a tenth aspect of the present invention, there is provided the transfer belt according to any one of the first to ninth aspects, wherein a transfer belt for transferring a toner image on each of the photoreceptors 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 eleventh aspect of the present invention, in the image forming unit according to any one of the first to tenth aspects, the image forming unit is provided with the photosensitive members arranged side by side at a bottom thereof, and is detached from the main body casing. In this state, there is provided an interference avoiding means for preventing interference of the mounting surface on which the image forming unit is mounted to the photoconductor.

  According to a twelfth aspect of the invention, there is provided the invention according to the eleventh aspect, wherein the interference avoiding means is composed of leg portions that protrude from the bottom surface of the frame to the lower side of the lower ends of the respective photoconductors.

  According to a thirteenth aspect of the present invention, the cartridge according to any one of the first to twelfth aspects is characterized in that the cartridge includes one of the developing units and is configured separately from the photosensitive member.

  A fourteenth aspect of the present invention is the cartridge according to any one of the first to twelfth aspects, wherein the cartridge includes a set of the developing device and the photosensitive member. It is characterized by being held together.

  According to a fifteenth 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 supports a pair of the developing device and the photosensitive member, and a plurality of cartridges that are configured to include at least one of the developing device or the photosensitive member and are detachably held by the frame; It is characterized in that it can be attached and detached.

  The invention of claim 16 is characterized in that, in the invention of claim 15, there is provided a grip portion for hand grip when lifting.

  According to a seventeenth aspect of the present invention, in the apparatus according to the sixteenth aspect, the drawer is allowed between the image forming unit and the main body casing to a drawer stop position where the cartridge can be attached and detached. A feature is provided in which a pull-out restricting means is provided for restricting the pull-out in the pull-out direction from the pull-out stop position and releasing the restriction, and the gripping part also serves as a release operation part for releasing the pull-out restricting means. Have

  The invention of claim 18 is characterized in that, in the invention of claim 16 or claim 17, the gripping portions are provided on both sides across a central axis along the drawing direction of the frame.

  According to a nineteenth aspect of the present invention, in the image forming unit according to the sixteenth or seventeenth aspect, the image forming unit is pulled out from the main body casing in a substantially horizontal direction, and the grip portion is provided in the image forming unit. It is characterized in that it can be displaced to a drawing position located at an end in the drawing direction and a lifting position located closer to the center of gravity in the drawing direction than the drawing position.

  According to a twentieth aspect of the present invention, when the handle member having the grip portion is rotatably attached to the frame, and the grip portion is in the lifting position. A stopper that abuts on the handle member and restricts rotation of the grip portion in a direction opposite to the pull-out position is provided, and the image forming unit is lifted with the grip portion in the lift position. In some cases, a torque is applied between the frame and the handle member in a direction in which the stopper is always pressed against the handle member regardless of the mounting state of the cartridges on the frame. .

  According to a twenty-first aspect of the present invention, in the image forming unit according to any one of the fifteenth to twentieth aspects, the photosensitive members are provided side by side at the bottom of the image forming unit, and are removed from the main casing. In this state, there is provided an interference avoiding means for preventing interference of the mounting surface on which the image forming unit is mounted to the photoconductor.

  According to a twenty-second aspect of the present invention, in the invention according to the twenty-first aspect, the interference avoiding means includes a leg portion protruding from a bottom surface of the frame to a lower side than a lower end of each photoconductor. Item 22. The image forming unit according to Item 21.

  According to a twenty-third aspect of the present invention, in the cartridge according to any one of the fifteenth to twenty-second aspects, the cartridge includes one of the developing units, and is configured separately from the photosensitive member. Has characteristics.

  According to a twenty-fourth aspect of the present invention, in the cartridge according to any one of the fifteenth to twenty-second 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.

<Invention of Claims 1 and 15>
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 2>
Since there is a removal restricting means for restricting the image forming unit from being pulled out, the image forming unit is stopped from being pulled out from the main body casing when the image forming unit is pulled out. The Therefore, it is possible to prevent an extra effort such as inadvertently pulling out the image forming unit when it is not necessary to remove it from the main body casing and mounting it again.

<Invention of Claim 3 and Claim 16>
Since the image forming unit is provided with a grip for gripping when lifting, the image forming unit can be easily carried by itself.

<Invention of Claims 4 and 17>
Since the grip portion also serves as a release operation portion of the removal restriction means, the release operation of the removal restriction means and the carrying of the image forming unit can be performed smoothly.

<Invention of Claims 5 and 18>
Since the gripping portions are provided on both sides of the central axis along the drawing direction of the frame, the image forming unit can be firmly held with both hands.

<Invention of Claims 6 and 19>
Since the gripping part can be displaced between the drawing position and the lifting position, when pulling out the image forming unit from the main body casing, pull the image forming unit from the main body casing by holding the pulling position gripping part. When removing and carrying, the image forming unit can be lifted by displacing the gripping portion to the lifting position. Therefore, workability is good because it is not necessary to change the hand holding the grip portion around.

<Invention of Claims 7 and 20>
When the image forming unit is lifted with the gripping portion in the lifting position, torque is always applied between the frame and the handle member in the direction in which the stopper is pressed against the handle member regardless of the mounted state of the cartridge. As a result, even when some of the cartridges are emptied or when the image forming unit is lifted with some of the cartridges removed from the frame, the direction of torque does not always change, so the frame is turned over. And can be lifted in a stable state.

<Invention of Claim 8>
When the image forming unit is pulled out, the grip portion provided at the end portion in the pull-out direction projects outward from the end portion of the cover in the opened state, so that it is easy to grip.

<Invention of Claim 9>
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 10>
Since each photoconductor is separated from the transfer belt when the image forming unit is pulled out, operations such as jamming and replacement of the transfer belt are easy.

<Invention of Claims 11 and 21>
Since the image forming unit is provided with interference avoiding means for preventing interference of the mounting surface with respect to each photoconductor provided along the bottom of the image forming unit, the image forming unit removed from the main body casing is placed on a desk or the like. It can be performed.

<Invention of Claims 12 and 22>
The interference avoiding means is composed of legs projecting downward from the bottom surface of each photoconductor from the bottom surface of the frame, so that each photoconductor does not interfere with the desk surface when the image forming unit is placed on a desk or the like. Supported in position.

<Invention of Claims 13 and 23>
Since the cartridge provided with the developing device 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 14 and 24>
Since the cartridge includes a set of the developing device and the photoconductor, both the developing device and the photoconductor can be exchanged at a time.

<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 the surface of a corresponding photosensitive drum 30 (described later) with laser light L for each color based on predetermined image data at high speed. 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, four developing cartridges 22 as a developing unit, and A cleaning brush 33 is held.

  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 with a roller body made of conductive urethane rubber or silicone rubber containing carbon fine particles. The surface of the roller body is covered with a coating layer of urethane rubber or silicone rubber 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 as an extending shaft. 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.
The configuration of the frame 21 and the like in the image forming unit 20 will be described in detail later.

  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 sheet 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 to It is conveyed backward along with the circular movement.

  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. The electrostatic latent image, that is, the surface of the photosensitive drum 30 that is uniformly positively charged, is supplied to an exposed portion exposed to a laser beam and having a lowered potential. 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 body casing 2, a paper discharge tray 47 whose front end side is substantially horizontal and whose rear end side is inclined rearwardly downward is provided. The paper 3 after image formation discharged from the paper discharge roller 46 is the paper discharge tray 47. Laminated on top.

  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 are provided at equal intervals in the front and rear direction behind the front wall 49 provided at the front end thereof. A cartridge mounting portion 51 opened upward is provided between each partition wall 50 and the partition wall 50 or the front wall 49 located on the front side thereof, and the above-described developing cartridge 22 is detachably mounted on each. It is like that. The front surface 50A of the partition wall 50 is slightly inclined downward toward the front side as it goes to the upper end side, and the rear surface 50B of the partition wall 50 is more than the front surface 50A toward the front side as it goes toward the upper end side. It is inclined upward at a large angle. The rear surface 49A of the front wall 49 is also inclined upward at the same angle as the rear surface 50B of the partition wall 50.

  In a state where each developing cartridge 22 is mounted on each cartridge mounting portion 51, the rear surface of the housing case 23 of the developing cartridge 22 is parallel to the front surface 50 </ b> A of the partition wall 50 with a predetermined space therebetween, and the front surface is the partition wall 50. Alternatively, it is parallel to the rear surfaces 50B and 49A of the front wall 49 with a predetermined interval. A guide (not shown) for guiding the mounting / demounting of the developing cartridge 22 is provided on the inner side wall of the cartridge mounting portion 51, and the developing cartridge 22 is guided by the guide to the rear surface 50 </ b> B or the front wall 49 of the partition wall 50. It is attached and detached in the direction along the rear surface 49A. In other words, the direction in which the developing cartridge 22 is detached is inclined toward the drawing direction (forward) of the image forming unit 20. The inner wall of the cartridge mounting portion 51 is provided with a locking means (not shown) for holding the developing cartridge 22 in a normal position, and the developing cartridge 22 is externally positioned in the cartridge mounting portion 51 from the normal position. Until the developing cartridge 22 is pulled out of the normal position, the locking means is released.

  The photosensitive drum 30 is held on the bottom of each cartridge mounting portion 51 at a position near the rear partition wall 50. 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 portion of each partition wall 50.

  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. 3) such as a desk, the rear leg portion 53 and the overhang portion 52 (both correspond to the interference avoiding means and the leg portion of the present invention). Is in contact with the plane, the bottom surface 21A of the frame 21 is maintained at a position separated from the plane, and thus 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 wall of the unit housing portion 19 in the main body casing 2, a removal restricting portion 56 that can be locked with the retaining protrusion 55 is provided so as to protrude downward toward the front end (the retaining protrusion 55 and the retaining restriction). The part 56 corresponds to the omission control means of the present invention.) 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, at the pull-out stop position, the front end portion (the overhang portion 52) of the frame 21 protrudes to the front side from the front end of the front cover 6 in the open position.

  A U-shaped handle member 58 is attached to the frame 21 of the image forming unit 20 so as to straddle the frame 21 from side to side. The handle member 58 includes a grip portion 58A that extends in the left-right direction and a pair of arm portions 58B that extend in parallel from both left and right ends. Each arm portion 58B is attached to a shaft portion 59 projecting from the left and right side walls 21B of the frame 21 at a position slightly closer to the gripping portion 58A from its extended end, and the handle member 58 is centered on the shaft portion 59. It can be turned. The shaft portion 59 is provided at a position closer to the rear end than the center in the front-rear direction of the frame 21 and in the vicinity of the upper end of the frame 21. The handle member 58 has a drawer position (see FIG. 2) in which the arm portion 58B is substantially horizontal and the grip portion 58A projects to the front side of the front wall 49 of the frame 21, and the arm portion 58B is inclined obliquely upward and the grip portion 58A is It can be displaced above the frame 21 to a lifting position (see FIG. 3) closer to the center in the front-rear direction (close to the center of gravity of the frame 21) than the position for drawing. Further, stoppers 60 are provided on both side walls 21B of the frame 21 so as to protrude below the shafts 59, and the stoppers 60 come into contact with the tip side portions of the arm portions 58B in the lifting position. As a result, the rotation of the handle member 58 in the direction opposite to the drawing position (counterclockwise direction in FIG. 3) is restricted. As a result, the entire image forming unit 20 can be lifted by gripping the gripping portion 58A with the handle member 58 in the lifting position. In this lifted state, as will be described later, torque is set between the frame 21 and the handle member 58 so as to apply a torque in a direction in which the stopper 60 is pressed against the handle member 58 regardless of the mounting state of each developing cartridge 22. ing.

When the image forming unit 20 is pulled out from the state shown in FIG. 1 in the laser printer 1 as described above, first the front cover 6 is opened, and then a finger is put on the gripping portion 58A of the handle member 58 in the pulling position. Then, 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.

  When removing the image forming unit 20 from the main casing 2, first, the grip portion 58 </ b> A of the handle member 58 is rotated from the pulling position to the lifting position. When the handle member 58 reaches the lifting position, the stopper 60 comes into contact with the arm portion 58B, and further rotation of the handle member 58 is restricted. Then, when the gripping portion 58A is further raised from this state, as shown in FIG. 3, the frame 21 is inclined so that the front end side is slightly lifted around the vicinity of the lower end of the rear end portion. After being spaced diagonally rearward and downward from the restricting portion 56, the locking of both 55 and 56 is released.

  Therefore, when the gripping portion 58A is pulled forward, the rear end of the frame 21 comes out of the unit accommodating portion 19 of the main body casing 2, and the image forming unit 20 can be lifted up alone. As described above, since the gripping portion 58A can be displaced between the pulling position and the lifting position, a series of operations from the pulling operation to the lifting operation can be smoothly performed without changing hands around.

  Here, when the image forming unit 20 is lifted with the gripping portion 58A, the stopper 60 is always pressed against the handle member 58 between the frame 21 and the handle member 58 regardless of the mounted state of each developing cartridge 22. Torque in the direction is applied. That is, as shown in FIG. 4A, when the image forming unit 20 is lifted with four developing cartridges 22 sufficiently filled with toner in the frame 21, the center of gravity (image The center of gravity of the members other than the handle member 58 in the forming unit 20 (see the arrow in the figure, the same applies hereinafter) is near the center of the frame 21 in the front-rear direction. Since the shaft portion 59 of the handle member 58 is disposed on the rear side of the center of gravity, the stopper 60 is pressed against the handle member 58 between the frame 21 and the handle member 58 (the frame 21 is rotated clockwise in FIG. 4). The torque in the direction of rotation) acts. Thereby, the frame 21 is maintained in a substantially horizontal posture. As shown in FIG. 4B, when the rear developing cartridge 22 is removed from the frame 21 and only the front three developing cartridges 22 are attached to the frame 21, the image forming unit 20 is lifted. The position of the center of gravity moves closer to the front end than in the case of FIG. For this reason, a torque in a direction in which the stopper 60 is pressed against the handle member 58 similarly acts between the frame 21 and the handle member 58, and the frame 21 is maintained in a substantially horizontal posture. Further, as shown in FIG. 4C, when only the rear developing cartridge 22 is left and the front three developing cartridges 22 are removed and lifted, the position of the center of gravity on the frame 21 side is the same figure. Although it moves closer to the rear end than in the case of (A), since it is on the front end side with respect to the position of the shaft portion 59, the direction of the torque is not changed and the frame 21 is maintained in a substantially horizontal posture. As described above, the direction of the torque does not change regardless of the mounting state of each developing cartridge 22, so that the frame 21 is lifted in a stable posture, and the frame 21 is turned over to drop the developing cartridge 22. Is prevented. Note that even when there is a difference in the remaining amount of toner in each developing cartridge 22 and the weight varies, the same direction as described above is exhibited because the direction of the torque does not always change.

  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, the rear leg portion 53 and the overhanging portion 52 come into contact with the flat surface T as shown by a chain line in FIG. The body drum 30 is held at a position 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, so that maintenance work such as jam processing in the main casing 2 and replacement of parts 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. Alternatively, as shown in a third embodiment to be described later, components such as the photosensitive drum 30 and the scorotron charger 31 may be detachable from the frame 21 so that each component can be replaced.

  As described above, according to the present embodiment, the image forming unit 20 can be attached to and detached from the main body casing 2, so that by removing the image forming unit 20 from the main body casing 2, jam processing and components in the main body casing 2 can be performed. Maintenance work such as replacement can be easily performed.

  In addition, since there are provided removal restriction means (55, 56) for restricting the removal of the image forming unit 20 from the drawing position, the image forming unit 20 stops at the drawing stop position when the image forming unit 20 is drawn. Thus, the exit from the main casing 2 is restricted. For this reason, it is possible to prevent the image forming unit 20 from being inadvertently pulled out when it is not necessary to remove it from the main casing 2 and being reattached.

  Further, since the image forming unit 20 is provided with a gripping portion 58A for gripping when lifting, the image forming unit 20 alone can be easily carried.

  In addition, since the gripping portion 58A also serves as a release operation portion of the removal restriction means (55, 56), the release operation of the removal restriction means (55, 56) and the carrying of the image forming unit 20 can be performed smoothly. .

  Further, since the gripping portion 58A can be displaced between the drawing position and the lifting position, when pulling out the image forming unit 20 from the main body casing 2, the gripping portion 58A is pulled out by holding the pulling position gripping portion 58A. When removing the forming unit 20 from the main casing 2 and carrying it, the image forming unit 20 can be lifted by displacing the gripping portion 58A to the lifting position. Accordingly, it is not necessary to change the hand holding the gripping portion 58A around, so workability is good.

  In addition, when the image forming unit 20 is lifted with the gripping portion 58A in the lifting position, the stopper 60 is always placed between the frame 21 and the handle member 58 regardless of the mounted state of the developing cartridges 22. Torque is applied in the direction of pressing. As a result, even when some of the developing cartridges 22 are emptied or when the image forming unit 20 is lifted with some of the developing cartridges 22 removed from the frame 21, the direction of torque does not always change. 21 can be lifted in a stable state without tipping over.

  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 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 image forming unit 20 is provided with interference avoiding means (52, 53) for preventing the interference of the mounting surface T with respect to the respective photosensitive drums 30 provided side by side at the bottom thereof, the image forming unit 20 is separated from the main casing 2. The removed image forming unit 20 can be placed on a desk or the like for work.

  Further, since the interference avoiding means includes the rear leg portion 53 and the overhanging portion 52 that protrude from the bottom surface of the frame 21 to the lower side of the lower end of each photosensitive drum 30, the image forming unit 20 is placed on a desk or the like. Then, each photosensitive drum 30 is supported at a height position that does not interfere with the desk surface or the like.

  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 this modification, instead of the retaining protrusion 55 of the above embodiment, an extending portion 62A is provided at the distal end of the arm portion 58B of the handle member 62, and the retaining protrusion projects in the upward direction at the leading end at the distal end. A portion 63 (corresponding to the drop restricting means of the present invention together with the drop restricting portion 56) is provided.

  When removing the image forming unit 20A of the present modified example from the normal mounting position in the main body casing 2, first, the gripping portion 58A of the handle member 62 in the pull-out position is gripped, and the image forming unit 20A is moved forward. Pull out. When the image forming unit 20A is pulled out to the pull-out stop position, the pull-out protrusion 63 comes into contact with the drop-out restricting portion 56 on the main body casing 2 side, and the pull-out stops (see the chain line in FIG. 5). Therefore, when the gripping portion 58A is raised, the retaining protrusion 63 is lowered and the locking with respect to the removal restricting portion 56 is released (see the solid line in FIG. 5). When the image forming unit 20A is moved to the front side after the handle member 62 is set to the lifting position, the image forming unit 20A can be lifted in a state separated from the main casing 2. Also by this modification, the same effect as the first embodiment can be obtained.

Second Embodiment
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, in the following description, about the site | part which has the same function as 1st Embodiment, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  In the image forming unit 64 of the present embodiment, a pair of arm members 66 extending substantially in the front-rear direction are attached to the left and right side surfaces 65 </ b> A of the frame 65. The front end of the arm member 66 is pivotably attached to the upper front end of the side surface 65A of the frame 65, and the rear end side is slightly lowered from the lock position (see FIG. 6A) where the arm member 66 is substantially horizontal. Thus, it is possible to displace between the inclined release position (see FIG. 6B). Further, the rear end of the arm member 66 is provided with a retaining protrusion 67 (corresponding to the removal restricting means 56 together with the removal restricting portion 56) protruding upward at the rear end position of the frame 65. Can be locked to the rear surface of the pull-out restricting portion 56 provided in the main body casing 2 when it is in the lock position, and when it is in the release position, it is lowered to a position where the lock is released. In addition, a spring member 68 that can be urged so as to maintain the arm member 66 in the locked position is attached to the vicinity of the rear end of both side surfaces 65A of the frame 65. In addition, a movable gripping portion 66 </ b> A is provided so as to project outward from the frame 65 at the approximate center in the front-rear direction of each arm member 66. Further, on both side surfaces 65A of the frame 65, a fixed grip portion 69 having a U-shaped cross section is provided below the movable grip portion 66A. The movable gripping portion 66 </ b> A and the fixed gripping portion 69 are symmetrically arranged on both sides across the central axis along the pulling direction in the frame 65.

  When the image forming unit 64 is pulled out from the main body casing 2 to the pulling stop position, as shown in FIG. 6A, the pull-out projection 67 of the arm member 66 abuts against the drop-out restricting portion 56 of the main body casing 2, and the image forming unit 64 64 omission is restricted. When the image forming unit 64 is removed from the main casing 2, the left and right movable gripping portions 66 </ b> A and the fixed gripping portion 69 are sandwiched from above and below with both hands, and each movable gripping portion 66 </ b> A is held as shown in FIG. It is made to approach the fixed grip part 69 side. As a result, the arm member 66 is rotated from the lock position to the release position, and the locking between the retaining protrusion 67 and the removal restricting portion 56 is released, so that the image forming unit 64 is pulled out to the front side while being held with both hands. And can be separated from the main casing 2.

  According to the present embodiment, since the movable gripping portion 66A and the fixed gripping portion 69 as gripping portions for hand grip when lifting are provided on both sides across the central axis along the pulling direction of the frame 65, the image The forming unit 64 can be firmly held with both hands.

  In addition, since the movable gripping portion 66A also serves as a release operation portion for the removal restriction means (56, 67), the release operation of the removal restriction means and the carrying of the image forming unit 64 can be performed smoothly.

<Third Embodiment>
Next, a third embodiment of the present invention will be described with reference to FIGS. In addition, about the site | part which has the same function as 1st Embodiment, the overlapping description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  FIG. 7 is a side sectional view showing a schematic configuration of a laser printer 1A as an image forming apparatus of the present embodiment. In the image forming unit 70 provided in the laser printer 1A, a handle portion 72 for gripping when being pulled out is recessed on the front surface of the front wall 49 of the frame 71. Further, a guide means for guiding the drawing operation of the image forming unit 70 is provided between the image forming unit 70 and the main casing 2. FIG. 8 is a front sectional view schematically showing an example of the guiding means. On both side walls 71A of the frame 71, a pair of guide rails 72A and 72B are provided along the front-rear direction so as to extend horizontally from both the upper and lower ends. On the other hand, guide grooves 73 into which the guide rails 72A and 72B can be fitted are provided along the front-rear direction on the left and right inner side walls of the unit housing portion 19 in the main body casing 2. The frame 71 is guided so as to slide in the front-rear direction in the unit housing portion 19 by fitting the left and right guide rails 72A and 72B into the guide groove 73. In the present embodiment, the retaining protrusion 55 is provided at the rear end of the upper surface of the upper guide rail 72 </ b> A, and the removal restricting portion 56 is provided at the front end position of the guide groove 73.

  When pulling out the image forming unit 70 from the main casing 2, the handle 72 is grasped and the image forming unit 70 is pulled out to the front side. When the image forming unit 70 is pulled out to the pull-out stop position, as shown in FIG. 7, the pull-out protrusion 55 abuts against the pull-out restricting portion 56 of the main casing 2 and the pull-out of the pull-out is restricted. At this time, the front end portion of the frame 71 protrudes forward from the front end of the opened front cover 6. In this state, when removing the image forming unit 70 from the main casing 2, the handle portion 72 is raised and the frame 71 is tilted to the front end raised position. As a result, the locking protrusion 55 is moved obliquely downward and rearward with respect to the drop-out restricting portion 56, and the locking is released. Therefore, the frame 71 is removed by moving the frame 71 forward while maintaining the inclined posture. Can do.

  According to the present embodiment, when the image forming unit 70 is pulled out, the handle portion 72 provided at the end portion in the pulling direction projects outward from the end portion of the opened front cover 6 so that it can be easily grasped. Therefore, it is easy to perform operations such as removing the image forming unit 70 from the main casing 2 and pushing it into the unit housing portion 19.

FIG. 9 shows a modification of the third embodiment.
In the first embodiment described above, the developing cartridge 22 as a developing device is shown to be detachable from the frame 21, but in the image forming unit 70 </ b> A of this modified example, 4 is detachable from the frame 75. Each of the two cartridges 76 includes a developing cartridge 77 as a developing unit and a photosensitive drum 30. 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. 10 shows another modification of the third embodiment. In the image forming unit 70B of this modified example, four cartridges 88 that can be attached to and detached from the frame 87 are a developing cartridge 89 as a developing device, a photosensitive drum 30, a scorotron charger 31, and a cleaning device, respectively. One set of brushes 33 is provided. The cartridge 88 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, the set of the developing cartridge 89, the photosensitive drum 30, the scorotron charger 31, and the cleaning brush 33 can be replaced at a time.

  11 and 12 show still another modification of the third embodiment. The image forming unit 70 </ b> C according to this modification includes four LED exposure devices 95 corresponding to the respective colors of black, cyan, magenta, and yellow. Each LED exposure device 95 is attached to the upper part of each of the four partition walls 97 in the frame 96, and is electrically connected to a frame-side connector 98 </ b> A provided at the rear end of the frame 96. The frame side connector 98A is connected to a main body side connector 98B fixed to the main body casing 2A side when the frame 96 is in the regular mounting position, whereby each LED exposure device 95 is controlled by a control circuit (not shown) in the main body casing 2. )). When the frame 96 is pulled out from the normal mounting position, the frame side connector 98A and the main body side connector 98B are cut (see FIG. 12). Each LED exposure device 95 includes a plurality of light emitting diodes (not shown) arranged in a line along the axial direction of the photosensitive drum 30, and a plurality of light emitting elements based on the corresponding color image data. An on-off control of the diode is performed to irradiate light onto the surface of the photosensitive drum 30 to form an electrostatic latent image on the photosensitive drum 30.

  In this modification, since the LED exposure device 95 is mounted on the image forming unit 70C, the exposure means on the main casing 2A side can be omitted, and the configuration is simplified.

<Fourth embodiment>
Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the following description, the right side in FIGS. 13 and 14 is the front. 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 lifted alone. 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 the image forming unit 103 is pulled out from the normal mounting position shown in FIG. 13, 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. 14). ). 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 lifting, 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. Further, since the image forming unit 103 can be attached to and detached from the main body casing 102, by removing the image forming unit 103 from the main body casing 102, maintenance work such as jam processing and component replacement in the main body casing 102 is easily performed. be able to.

<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 directly transfers to a recording medium is exemplified. However, in the present invention, an intermediate transfer member (such as an intermediate transfer belt or an intermediate transfer drum) is used for the recording medium. The present invention can also be applied to a color laser printer of an intermediate transfer system that performs transfer via the printer.
(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.

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 the process of removing the image forming unit from the main casing. (A)-(C) Explanatory drawing which shows the relationship between the mounting state of a cartridge, and the force which acts. The sectional side view which shows the process in which the laser printer in the modification of 1st Embodiment is removed from a main body casing. The side view which shows schematic structure of the image forming unit in 2nd Embodiment. Sectional drawing which shows the state which pulled out the image forming unit of the laser printer in 3rd Embodiment Front sectional view for explaining an example of guiding means Side sectional view showing an image forming unit in a modification of the third embodiment Side sectional view showing an image forming unit in another modification of the third embodiment Side sectional view showing a laser printer in still another modification of the third embodiment Side sectional view showing a state in which the image forming unit is pulled out from the main body casing. Side view showing a schematic configuration of an image forming unit according to the fourth 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)
6. Front cover (cover)
7. Paper feed tray (supply tray)
20, 64, 70, 70A, 70B, 70C, 103 ... image forming units 21, 65, 71, 75, 87, 96, 113 ... frames 22, 118 ... developing cartridge (cartridge, developing device)
30, 101 ... Photosensitive drum (photosensitive member)
38, 107 ... transfer belt (paper transport belt)
52 ... Overhang (interference avoiding means, leg)
53 ... Rear leg (interference avoiding means, leg)
55, 63, 67 ... Anti-protrusion protrusion (detachment restricting means)
56. Omission control part (Omission control means)
58, 62 ... handle members 58A, 114 ... gripping portion 60 ... stopper 66A ... movable gripping portion (gripping portion)
69: Fixed gripping part (grip part)
72: Handle portions 76, 88 ... Cartridges 77, 89 ... Developer cartridge (developer)

Claims (24)

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. A tandem image forming apparatus configured to be transferred to
The main body casing includes at least one of a frame for supporting the plurality of sets of developing devices and the photosensitive member, and one of the developing device or the photosensitive member, and a plurality of the plurality of sets that are detachably held on the frame. An image forming unit provided with a cartridge is provided so as to be drawable with respect to the main body casing.
The image forming apparatus, wherein the image forming unit is detachable from the main casing. A pull-out restricting means that allows the image forming unit to be pulled out to a pull-out stop position at which the cartridge can be attached and detached, and that restricts the pull-out from the pull-out stop position in the pull-out direction and can release the restriction. The image forming apparatus according to claim 1, further comprising: The image forming apparatus according to claim 1, wherein the image forming unit is provided with a grip portion for hand grip when the image forming unit is lifted. The image forming unit is provided with a grip portion for gripping when lifting, and the grip portion also serves as a release operation portion for releasing the drop-out restricting means. Item 3. The image forming apparatus according to Item 2. 5. The image forming apparatus according to claim 3, wherein the gripping portions are provided on both sides of a central axis along a drawing direction of the frame. The image forming unit is pulled out in a substantially horizontal direction from the main body casing,
The grip portion is displaceable to a drawing position located at an end portion in the drawing direction of the image forming unit and a lifting position located closer to the center of gravity in the drawing direction than the drawing position. The image forming apparatus according to claim 3, wherein the image forming apparatus is an image forming apparatus. A handle member provided with the grip portion is rotatably attached to the frame, and the grip portion comes into contact with the handle member when the grip portion is in the lifting position and the pull-out position is Is provided with a stopper that restricts rotation in the direction toward the opposite side,
When the image forming unit is lifted with the gripper in the lifting position, the stopper is always placed between the frame and the handle member regardless of the mounting state of the cartridges on the frame. The image forming apparatus according to claim 6, wherein a torque is applied in a direction of pressing the member. The image forming unit is pulled out in a substantially horizontal direction from the main body casing,
The image forming unit is provided with a handle for gripping at the time of pulling out at an end in the pulling direction,
The main body casing is provided with a cover that covers the side surface of the image forming unit in the pull-out direction so as to be openable and closable, and the cover is opened by tilting the upper end side in the pull-out direction around the lower end side ,
8. The apparatus according to claim 1, wherein when the image forming unit is pulled out, the handle portion is configured to project outward from an end portion of the cover in an open state. 9. Image forming apparatus. 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 8. 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. The image forming apparatus according to claim 1, wherein the image forming unit is configured to be separated from the transfer belt when the image forming unit is pulled out. The image forming unit is provided with the respective photoconductors side by side at the bottom thereof, and when the image forming unit is detached from the main body casing, interference of the mounting surface on which the image forming unit is mounted with respect to the photoconductor. The image forming apparatus according to claim 1, further comprising an interference avoidance unit for preventing the interference. The image forming apparatus according to claim 11, wherein the interference avoiding unit includes a leg portion protruding from a bottom surface of the frame to a lower side than a lower end of each photoconductor. The image forming apparatus according to claim 1, wherein the cartridge includes one of the developing devices and is configured separately from the photosensitive member. 13. The cartridge according to claim 1, wherein the cartridge includes a pair of the developing device and the photoconductor, and the developing device and the photoconductor 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 supports the plurality of sets of developing units and the photosensitive member, and a plurality of cartridges that include at least one of the developing unit or the photosensitive member and are detachably held on the frame;
An image forming unit, wherein the image forming unit is detachable from the main casing. The image forming unit according to claim 15, further comprising a grip portion for hand grip when lifting. Between the image forming unit and the main body casing, the cartridge is allowed to be pulled out to a pull-out stop position where the cartridge can be attached and detached, and is prevented from being pulled out from the pull-out stop position in the pull-out direction. 17. The image forming unit according to claim 16, further comprising: a disengagement restricting unit capable of releasing the disengagement, wherein the grip portion also serves as a release operation unit for releasing the disengagement restricting unit. 18. The image forming apparatus according to claim 16, wherein the gripping portions are provided on both sides of a central axis along a drawing direction of the frame. The image forming unit is pulled out from the main casing in a substantially horizontal direction,
The grip portion is displaceable to a drawing position located at an end portion in the drawing direction of the image forming unit and a lifting position located closer to the center of gravity in the drawing direction than the drawing position. The image forming unit according to claim 16, wherein the image forming unit is an image forming unit. A handle member provided with the grip portion is rotatably attached to the frame, and the grip portion comes into contact with the handle member when the grip portion is in the lifting position and the pull-out position is Is provided with a stopper that restricts rotation in the direction toward the opposite side,
When the image forming unit is lifted with the gripper in the lifting position, the stopper is always placed between the frame and the handle member regardless of the mounting state of the cartridges on the frame. The image forming unit according to claim 19, wherein a torque is applied in a direction of pressing the member. The image forming unit is provided with the respective photoconductors side by side at the bottom thereof, and when the image forming unit is detached from the main body casing, interference of the mounting surface on which the image forming unit is mounted with respect to the photoconductor. 21. The image forming unit according to claim 15, further comprising interference avoiding means for preventing the interference. The image forming unit according to claim 21, wherein the interference avoiding unit includes a leg portion protruding from a bottom surface of the frame to a lower side than a lower end of each photoconductor. The image forming unit according to any one of claims 15 to 22, wherein the cartridge includes one of the developing devices and is configured separately from the photosensitive member. The cartridge according to any one of claims 15 to 22, wherein the cartridge includes a pair of the developing device and the photoconductor, and the developing device and the photoconductor are integrally held with each other. The image forming unit described in 1.

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