JP5218574B2 - Image forming apparatus and process cartridge - Google Patents

Description

  The present invention relates to an image forming apparatus and a process cartridge.

A tandem color laser printer is known as an electrophotographic image forming apparatus. For example, the device described in Patent Document 1 includes a plurality of image forming units each including a photosensitive drum, a developing device, a charger, and the like in a main body casing. Each image forming unit is housed in a box-shaped drawer, and is configured such that the developing device and the like of each image forming unit can be exchanged in a state where the drawer is pulled forward from the main body casing.
JP 2003-107838 A

  In such an image forming apparatus, for example, a guide wall extending in the front-rear direction is provided in the main body casing, and the drawing operation and insertion operation of the drawer portion are guided by the guide wall. And in the state where the drawer part is pulled out, the supported part provided at the rear part of the drawer part comes into contact with the downward surface of the guide wall, and the guide wall supports the upward load received from the supported part, The drawer portion is restricted from being tilted up and down.

  However, when the weight of the component mounted on the drawer portion is large, the load applied to the supported portion at the time of pulling out becomes large, so that the drawer operation and insertion operation of the drawer portion become heavy, and the operability is deteriorated. There's a problem. As a countermeasure, it is conceivable to reduce the load applied to the supported portion by arranging the supported portion further rearward. However, in order to dispose the supported portion further rearward, if the shape of the entire drawing portion is extended rearward, the size of the device is increased accordingly.

  The present invention has been completed based on the above-described circumstances, and it is an object of the present invention to ensure the operability of the drawer and to avoid the enlargement of the apparatus.

An image forming apparatus according to the present invention includes an apparatus main body having a guide wall, a plurality of image forming units for forming an image on a recording medium, and a pull-out direction along the guide wall with respect to the apparatus main body. A drawer portion provided; and a belt disposed below the drawer portion.
The drawer portion includes a unit housing portion that houses the plurality of image forming units, a projecting portion that projects upstream of the unit housing portion in the pulling direction , a first supported portion, and the pulling portion in the pulling direction. It provided in the upper stream side of the first supported portion, and a second supported portion provided on the projecting portion.
The guide wall includes a downward first guide surface extending in the pull-out direction, an upward second guide surface provided so as to face the first guide surface in parallel with a predetermined interval, The second guide surface has an upward guide surface that is continuous with the downstream end in the pull-out direction and is inclined upward toward the downstream end.
During withdrawal operation of the lead portion, the the first guide surface in contact said second supported portion are those, in the second guide surface in contact said first supported portion are brought, the vertical direction of the drawing portion Regulate tilt to The guide surface contacts the first supported portion when the drawer portion is attached to the apparatus main body, and the drawer portion is gradually separated from the belt as the drawer portion is pulled out. The first supported part is guided.

In the image forming apparatus of the present invention, the first and second supported parts for restricting the tilting of the drawer part in the vertical direction are provided on the upstream side in the drawer direction of the drawer part. The load applied to the second supported portion is reduced, and the operability of the drawer portion can be ensured. In addition, since the second supported portion is provided in the protruding portion that protrudes upstream in the pull-out direction with respect to the unit accommodating portion, other components are arranged in the space behind the unit accommodating portion (the space overlapping the protruding portion). This makes it possible to avoid an increase in the size of the apparatus. Further, since the drawer portion is separated from the belt by the guide surface along with the drawer operation, the drawer portion can be smoothly pulled out without the image forming unit and the belt being in sliding contact during the drawer operation.

<Embodiment 1>
Next, Embodiment 1 of the present invention will be described with reference to FIGS.
(Whole structure of laser printer)
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. In the following description, the right side in each figure is the front.

  The laser printer 1 is a direct transfer tandem color laser printer, and includes a substantially box-shaped main body casing 2 (corresponding to the “apparatus main body” of the present invention) as shown in FIG. An opening 2A is provided on the front surface (one side surface) of the main body casing 2, and a front cover 3 that covers the opening 2A so as to be openable and closable is attached. By opening the front cover 3, it is possible to attach and detach the process unit 25 and the belt unit 15 in the main body casing 2 and eliminate jams that occur in the main body casing 2. Further, on the upper surface of the main casing 2, a paper discharge tray 5 on which paper 4 as a recording medium after image formation is stacked is formed.

  A paper feed tray 7 on which paper 4 for forming an image is loaded is attached to the lower portion of the main body casing 2 so as to be drawn forward. In the paper feed tray 7, there is provided a paper pressing plate 9 that can be tilted to lift the front end side of the paper 4 by the bias of the spring 8. In addition, a pickup roller 10 and a separation pad 11 that presses against the pickup roller 10 by biasing a spring (not shown) are provided at a position above the front end of the paper feed tray 7. Further, a pair of paper feed rollers 12 is provided obliquely in front of the pickup roller 10, and a pair of registration rollers 13 and a pair of guide portions 14 </ b> A and 14 </ b> B are provided thereabove.

  When the uppermost sheet 4 of the sheet feeding tray 7 is pressed toward the pickup roller 10 by the sheet pressing plate 9 and is sandwiched between the pickup roller 10 and the separation pad 11 by the rotation of the pickup roller 10, 1 is reached. Separated by sheet. Then, the paper 4 sent out between the pickup roller 10 and the separation pad 11 is sent to the registration roller 13 by the paper feed roller 12. The registration roller 13 corrects the skew of the sheet 4 and then feeds the sheet 4 to the downstream side at a predetermined timing. The guide units 14A and 14B guide the sheet 4 onto the conveying belt 18 of the belt unit 15.

  The belt unit 15 is attachable to and detachable from the main casing 2 and includes a conveyor belt 18 that is horizontally installed between a pair of belt support rollers 16 and 17 that are spaced apart from each other in the front-rear direction. The conveyor belt 18 is an endless belt made of a resin material such as polycarbonate, and is circulated and moved counterclockwise in FIG. 1 when the rear belt support roller 17 is driven to rotate, and is placed on the upper surface thereof. The paper 4 is conveyed backward. Inside the conveying belt 18, four transfer rollers 19 arranged to face each photosensitive drum 31 included in the image forming unit 26 described later are arranged at regular intervals in the front-rear direction, and a transfer corresponding to each photosensitive drum 31 is provided. The conveying belt 18 is sandwiched between the rollers 19. At the time of transfer, a transfer bias is applied between the transfer roller 19 and the photosensitive drum 31.

  A cleaning roller 21 is provided below the belt unit 15 to remove toner, paper dust, and the like attached to the conveyance belt 18. The cleaning roller 21 has a structure in which a foam material made of silicon is provided around a metal shaft member, and is opposed to the metal backup roller 22 provided in the belt unit 15 with the conveyance belt 18 interposed therebetween. Yes. A predetermined bias is applied between the cleaning roller 21 and the backup roller 22, whereby the toner and the like on the conveyor belt 18 are electrically attracted to the cleaning roller 21 side. Further, the cleaning roller 21 is in contact with a metal recovery roller 23 that removes toner or the like adhering to the surface, and the recovery roller 23 is a blade for scraping off the toner or the like adhering to the surface. 24 abuts.

  A scanner unit 27 is provided at an upper portion in the main body casing 2, a process unit 25 is provided on the lower side (the back side of the opening 2 </ b> A), and the belt unit 15 is further provided on the lower side of the process unit 25. Has been placed.

  The scanner unit 27 irradiates the surface of the corresponding photosensitive drum 31 with laser light L for each color based on predetermined image data at high speed scanning.

  The process unit 25 (corresponding to the “drawer unit” and “process cartridge” of the present invention) includes four image forming units 26 corresponding to the colors magenta, yellow, cyan, and black, and these image forming units 26. Are arranged side by side. Each image forming unit 26 includes a photosensitive drum 31 as an image carrier, a scorotron charger 32, a developing cartridge 34 as a developing device, and the like. Further, the process unit 25 includes a frame-like frame 29 having four cartridge mounting units 30 arranged in the front-rear direction. Each cartridge mounting part 30 is opened up and down, and each developing cartridge 34 can be attached / detached inside thereof. The frame 29 holds the photosensitive drum 31 of each image forming unit 26 at the lower end position of each cartridge mounting portion 30, and further holds the scorotron charger 32 adjacent to the photosensitive drum 31. As will be described later in detail, the process unit 25 is detachably and detachably attached to the main casing 2.

  The photosensitive drum 31 includes a grounded metal drum body, and the surface layer is covered with a positively chargeable photosensitive layer made of polycarbonate or the like.

  The scorotron charger 32 is disposed opposite to the photosensitive drum 31 at a predetermined interval so as not to come into contact with the photosensitive drum 31 at an obliquely upper rear side of the photosensitive drum 31. The scorotron charger 32 uniformly charges the surface of the photosensitive drum 31 to positive polarity by generating corona discharge from a charging wire (not shown) such as tungsten.

  The developing cartridge 34 has a substantially box shape, and a toner storage chamber 38 is provided in an upper portion thereof, and a supply roller 39, a developing roller 40, and a layer thickness regulating blade 41 are provided below the developing cartridge 34. Each toner storage chamber 38 stores positively chargeable nonmagnetic one-component toner of each color of yellow, magenta, cyan, and black as a developer. Each toner storage chamber 38 is provided with an agitator 42 for stirring the toner.

  The supply roller 39 is configured by coating a metal roller shaft with a conductive foam material, and the developing roller 40 is configured by coating the metal roller shaft with a conductive rubber material. Yes. The toner discharged from the toner storage chamber 38 is supplied to the developing roller 40 by the rotation of the supply roller 39 and is positively frictionally charged between the supply roller 39 and the developing roller 40. Further, the toner supplied onto the developing roller 40 enters between the layer thickness regulating blade 41 and the developing roller 40 with the rotation of the developing roller 40, where it is further sufficiently frictionally charged to have a constant thickness. It is carried on the developing roller 40 as a thin layer.

  The surface of the photosensitive drum 31 is uniformly positively charged by the scorotron charger 32 when rotating. Thereafter, exposure is performed by high-speed scanning of laser light from the scanner unit 27, and an electrostatic latent image corresponding to an image to be formed on the paper 4 is formed.

  Next, the electrostatic latent toner formed on the surface of the photosensitive drum 31 when the positively charged toner carried on the developing roller 40 comes into contact with the photosensitive drum 31 by rotation of the developing roller 40. Supplied to the image. As a result, the electrostatic latent image on the photosensitive drum 31 is visualized, and the surface of the photosensitive drum 31 carries a toner image with toner attached only to the exposed portion.

  Thereafter, the toner image carried on the surface of each photosensitive drum 31 is transferred to the transfer roller 19 while the paper 4 conveyed by the conveyance belt 18 passes through each transfer position between the photosensitive drum 31 and the transfer roller 19. Are sequentially transferred onto the paper 4 by a negative transfer bias applied to the sheet 4. The sheet 4 having the toner image transferred thereon is then conveyed to the fixing device 43.

  The fixing device 43 is disposed behind the conveyance belt 18 in the main body casing 2. The fixing device 43 includes a heating roller 44 that is rotationally driven with a heat source such as a halogen lamp, and a pressure roller 45 that is disposed below the heating roller 44 so as to face the heating roller 44 and is driven to rotate. It has. The fixing device 43 fixes the toner image on the paper 4 by heating the paper 4 carrying the four color toner images while nipping and conveying the paper 4 by the heating roller 44 and the pressure roller 45. The heat-fixed paper 4 is transported to a paper discharge roller 47 provided on the upper portion of the main body casing 2 by a transport roller 46 disposed obliquely above and rearward of the fixing device 43, and the paper discharge roller 47 performs the above-described operation. The paper is discharged onto the paper discharge tray 5.

(Support structure of process part)
2 is a side sectional view showing a state in which the front cover 3 is opened, FIG. 3 is a side sectional view showing a state in the middle of pulling out the process unit 25, and FIG. 4 is a state in which the drawing operation of the process unit 25 is restricted. FIG. 5 is a side sectional view showing a state in the middle of removing the process unit 25.

  The frame 29 of the process unit 25 includes a unit storage unit 50 that stores the above-described four image forming units 26, and a handle 51 for gripping is formed on the upper front side of the unit storage unit 50. Yes. Further, on the rear side of the unit accommodating portion 50, an overhanging portion 52 having the same height and the same width as the unit accommodating portion 50 is formed to project rearward. The rear end portion of the unit accommodating portion 50 projects rearward as it goes downward, and the front portion of the projecting portion 52 overlaps the portion projecting rearward of the unit accommodating portion 50 in the vertical direction. Further, the rear end surface of the overhanging portion 52 is a vertical surface (that is, a surface orthogonal to the drawing direction of the process portion 25), and a protruding portion 53 that partially protrudes rearward over the rear end surface extends over the entire width. Is formed. In the main body casing 2, the fixing device 43 described above is located at a position behind the unit housing portion 50 (behind the overhang portion 52) and vertically with respect to the protruding portion 53 (that is, in a direction perpendicular to the pulling direction). Is arranged.

  A first supported portion 54 (corresponding to the “locking portion” of the present invention) made of a rotatable rotating body is attached to the upper portions of the left and right sides of the overhang portion 52. Further, second supported portions 55 made of a rotatable rotating body are attached to the left and right side surfaces of the protruding portion 53. The second supported portion 55 has an outer diameter slightly larger than that of the first supported portion 54, and is attached at a position slightly rearward and slightly above the first supported portion 54. In addition, at the upper ends of the left and right side surfaces of the frame 29, a plate-shaped fulcrum receiving wall 56 extending in the front-rear direction (drawing direction) forward from the position of the first supported portion 54 and projecting horizontally outward. Is formed. The fulcrum receiving wall 56 includes a downward horizontal surface 56A extending in the front-rear direction, and a downward guide surface 56B (corresponding to “guidance means” of the present invention) that is inclined forward and connected to the front end.

  On the other hand, a pair of upper and lower guide walls 58 and 59 are provided in the main body casing 2 on both the left and right sides of the process unit 25. Each of the guide walls 58 and 59 extends in the front-rear direction (lateral direction) and has a length dimension that is approximately the same as the length dimension of the process unit 25. The upper guide wall 58 is provided with a downward guide surface 58A, and the lower guide wall 59 is provided with an upward guide surface 59A. These guide surfaces 58A and 59A are parallel to each other and are predetermined. It is provided so as to face each other with an interval. A pair of supported portions 54 and 55 of the process portion 25 can enter the groove portion 60 formed between the both guide walls 58 and 59 (both guide surfaces 58A and 59A), and the first supported portion. The process portion 25 is supported by the guide walls 58 and 59 when 54 is in contact with the lower guide surface 59A and the second supported portion 55 is in contact with the upper guide surface 58A. Further, at the rear end position of the lower guide wall 59, an upward guide surface 59B (corresponding to the “guide means” of the present invention) is formed which is continuous with the rear end of the guide surface 59A and is inclined upward from the front end. Yes.

  Further, a fulcrum receiving wall 56 of the process section 25 is disposed in the groove 60 between the guide walls 58 and 59 so as not to contact the upper and lower guide surfaces 58A and 59A. Furthermore, a fulcrum portion 61 (corresponding to the “stopper” of the present invention) is provided at the front end position of the lower guide surface 59A (front end position of the groove portion 60). The fulcrum portion 61 is a rotating body that is rotatably held. For example, the outer periphery of the rotating shaft is covered with an elastic member such as rubber. The outer diameter of the fulcrum part 61 is larger than the outer diameter of the first supported part 54. The fulcrum part 61 supports the process part 25 by placing a fulcrum receiving wall 56 on the upper surface.

(Operation of this embodiment)
In the state in which the process unit 25 is mounted at the proper apparatus position in the main body casing 2, the guide surface 56B of the fulcrum receiving wall 56 is placed on the upper surface of the fulcrum unit 61 as shown in FIGS. Since the supported portion 54 is placed on the guide surface 59B of the guide wall 59, the process portion 25 is supported in a horizontal posture by the fulcrum portion 61 and the guide wall 59. At this time, each photosensitive drum 31 is placed on the upper surface of the transport belt 18. Abut.

  When the process unit 25 is pulled out from the main casing 2, first, as shown in FIG. 2, the front cover 3 is opened, and then the process unit 25 is pulled out forward. Then, along with this drawing operation, the front end portion of the fulcrum receiving wall 56 and the first supported portion 54 are lifted almost simultaneously by the guidance of both guide surfaces 56B, 59B, and the process portion 25 moves obliquely forward and upward. As a result, the photosensitive drums 31 of the process unit 25 are separated from the conveyance belt 18, so that the photosensitive drums 31 are not in sliding contact with the conveyance belt 18, so that the drawing operation of the process unit 25 can be performed smoothly.

  Then, as shown in FIG. 3, the horizontal surface 56A of the fulcrum receiving wall 56 rides on the fulcrum portion 61, the first supported portion 54 rides on the guide surface 59A of the lower guide wall 59, and further the second covered portion. The support portion 55 contacts the guide surface 58A of the upper guide wall 58. In this state, a rotational moment in the counterclockwise direction shown in the figure is applied to the process portion 25 around the fulcrum portion 61, and the downward guide wall 59 is received downward from the first supported portion 54 by the rotational moment. Supports the load. In this state, the lower end of the process unit 25 (the lower end of the photosensitive drum 31) is held at a position higher than the guide unit 14A provided near the lower end of the opening 2A.

  When the process part 25 is further pulled out from the state of FIG. 3, the supported parts 54 and 55 come into contact with the guide walls 58 and 59, respectively, so that the vertical tilting of the process part 25 is restricted. 25 is guided forward while maintaining a horizontal posture. When the center of gravity of the process part 25 reaches the front of the position of the fulcrum part 61, a rotational moment in the clockwise direction acts on the process part 25 around the fulcrum part 61, and the upper guide wall 58 rotates. The upward load received from the second supported portion 55 is supported by the moment.

  Then, as shown in FIG. 4, when the process unit 25 is pulled out to a position where almost the entire unit accommodating unit 50 is exposed to the outside of the opening 2 </ b> A, the first supported unit 54 contacts the rear surface of the fulcrum unit 61. The two 54 and 61 are brought into contact with each other, and the drawing operation of the process unit 25 is restricted. Here, when the outer diameter of the first supported portion 54 is larger than the outer diameter of the fulcrum portion 61 (more precisely, the center of the first supported portion 54 is above the center of the fulcrum portion 61). When both 54 and 61 contact | abut, there exists a possibility that the 1st to-be-supported part 54 may ride on the fulcrum part 61, and the process part 25 may remove | deviate. On the other hand, in the present embodiment, the outer diameter of the first supported portion 54 is smaller than the outer diameter of the fulcrum portion 61 (the center of the first supported portion 54 is below the center of the fulcrum portion 61). Therefore, the engagement between the two 54 and 61 is difficult to disengage, and therefore the process unit 25 is prevented from being disengaged. In this state where the process unit 25 is pulled out, each developing cartridge 34 can be replaced.

  When removing the process part 25 from the main body casing 2 from the state shown in FIG. 4, the handle part 51 is grasped, the front end side of the process part 25 is lifted, and the process part 25 is inclined to the posture of lowering the rear end. Then, first, the second supported portion 55 descends and comes into contact with the lower guide surface 59A, and then the first supported portion 54 rises from the guide surface 59A and the engagement with the fulcrum portion 61 is released. (See FIG. 5). At this time, since the first supported portion 54 and the fulcrum portion 61 are both rotatable, the engagement can be easily released. FIG. 5 shows a state in which the process unit 25 is tilted and then a handle (not shown) provided on the rear side of the process unit 25 is gripped and the rear side of the process unit 25 is slightly lifted. When the process unit 25 is pulled obliquely forward and upward with the process unit 25 tilted, the process unit 25 is detached from the main casing 2. By removing the process unit 25 from the main body casing 2 in this way, replacement of the process unit 25 (for example, when the photosensitive drum 31 is deteriorated), replacement of the belt unit 15, or maintenance such as jam processing in the main body casing 2 is performed. be able to.

  When the process part 25 removed from the main body casing 2 is mounted in the main body casing 2 again, the supported parts 54 and 55 are placed with the process part 25 in the posture of lowering the rear end in a manner opposite to the above procedure. Is inserted into the groove portion 60, and then the process portion 25 is pushed into the back side in a horizontal posture. When the first supported portion 54 reaches the guide surface 59B of the guide wall 59 and the fulcrum portion 61 reaches the guide surface 56B of the fulcrum receiving wall 56, the process portion 25 moves obliquely downward while maintaining a substantially horizontal posture. As a result, the photosensitive drum 31 comes into contact with the upper surface of the conveyor belt 18.

(Effect of this embodiment)
As described above, according to the present embodiment, since the supported portions 54 and 55 for restricting the tilting of the process portion 25 in the vertical direction are provided behind the unit accommodating portion 50, the supported portions are supported when being pulled out. The load applied to the parts 54 and 55 is reduced, and the operability when the process part 25 is pulled out can be ensured. In addition, since the first supported portion 54 is provided in the protruding portion 53 that protrudes rearward with respect to the unit accommodating portion 50, other components are provided in the space behind the unit accommodating portion 50 (the space overlapping the protruding portion 53). Can be arranged, and the enlargement of the apparatus can be avoided.

  In addition, since the fixing device 43 is disposed behind the process unit 25 in the main body casing 2 at a position overlapping the protruding portion 53, space efficiency is good.

  In addition, since both the supported parts 54 and 55 are made of a rotating body, the resistance generated between the supported parts 54 and 55 and the guide walls 58 and 59 when the process part 25 is pulled out or inserted is reduced, and the operation is reduced. It can be done smoothly.

  When the process portion 25 is pulled out, the fulcrum portion 61 of the main body casing 2 is locked to the first supported portion 54 as the locking portion of the process portion 25, so that the pulling operation is restricted. When it is not necessary to remove from the casing 2, it can be prevented from being accidentally extracted.

  Moreover, since the process part 25 can be removed from the main body casing 2, it is convenient when the maintenance in the main body casing 2 is performed.

  Furthermore, since the first supported portion 54 also serves as a locking portion for locking to the fulcrum portion 61, the configuration of the process portion 25 is simplified.

  Moreover, the process part 25 is supported by mounting the fulcrum receiving wall 56 on the upper surface of the fulcrum part 61 provided in the main body casing 2. When a rotational moment around the fulcrum part 61 is generated in the process part 25, the supported parts 54 and 55 are supported in contact with the guide walls 58 and 59, whereby the tilt of the process part 25 is restricted.

  Further, since the fulcrum part 61 is made of a rotating body, the resistance generated between the fulcrum part 61 and the fulcrum receiving wall 56 when the process part 25 is pulled out or inserted is reduced, and the operation can be performed smoothly.

  Furthermore, since the fulcrum part 61 also serves as a stopper for restricting the drawing operation of the process part 25, the configuration on the main body casing 2 side is simplified.

  Further, since the fulcrum receiving wall 56 is disposed between the pair of guide surfaces 58A and 59A opposed to each other in the vertical direction, it is not necessary to separately provide a groove or the like for receiving the fulcrum receiving wall 56 in the main body casing 2. As a result, space efficiency is improved and the apparatus can be miniaturized.

  In addition, the process unit 25 is separated from the conveyor belt 18 by the guide surfaces 56B and 59B in accordance with the drawing operation. Therefore, the image forming unit 26 and the transport belt 18 are not in sliding contact during the pulling operation, and the process unit 25 can be pulled out smoothly.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS. In the following description, configurations different from those in the first embodiment will be mainly described, and configurations having the same functions as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.
6 is a side sectional view showing a state in which the front cover 3 is opened, FIG. 7 is a side sectional view showing a state in the middle of pulling out the process unit 65, and FIG. 8 is a state in which the drawing operation of the process unit 65 is restricted. FIG. 9 is a side sectional view showing a state in the middle of removing the process unit 65.

  The process unit 65 included in the laser printer 1A according to the present embodiment includes a single supported portion made of a rotatable rotating body on the left and right side surfaces of the protruding portion 53 instead of the supported portions 54 and 55 in the first embodiment. 66. The outer diameter of the supported portion 66 is set to be larger than the outer diameter of the fulcrum portion 61 and slightly smaller than the width dimension between the guide surfaces 58A and 59A. In addition, a guide surface 59 </ b> C that rises at the front end for guiding the supported portion 66 is formed at the rear end portion of the lower guide wall 59 in the main body casing 2.

  Further, a pair of left and right stoppers 68 that can be rotated are provided in the vicinity of the inner lower portion of the opening 2 </ b> A in the main casing 2. The stopper 68 has a hook-shaped tip 68A projecting inwardly. On the other hand, a locking portion 69 that can be engaged with the front end portion 68 </ b> A of the stopper 68 protrudes from the lower portions of the left and right side surfaces of the overhang portion 52 in the process portion 65.

  In a state in which the process unit 65 is mounted at a proper apparatus position in the main body casing 2, the guide surface 56B of the fulcrum receiving wall 56 is placed on the upper surface of the fulcrum portion 61 and the supported portion 66 is By being placed on the guide surface 59C of the guide wall 59, the process unit 65 is supported in a horizontal posture. When the process portion 65 is pulled forward from this state, the front end portion of the fulcrum receiving wall 56 and the supported portion 66 are lifted almost simultaneously by the guidance of both guide surfaces 56B and 59C, The process unit 65 moves diagonally forward and upward. As a result, each photosensitive drum 31 of the process unit 65 is separated from the transport belt 18.

  As shown in FIG. 7, the horizontal surface 56 </ b> A of the fulcrum receiving wall 56 rides on the fulcrum portion 61, and the supported portion 66 rides on the guide surface 59 </ b> A of the lower guide wall 59. In this state, a rotational moment in the counterclockwise direction shown in the drawing is applied to the process portion 65 around the fulcrum portion 61, and the downward load that the lower guide wall 59 receives from the supported portion 66 due to the rotational moment is applied. I support it.

  In the process in which the process unit 65 is pulled out, the supported portion 66 abuts against the guide walls 58 and 59 to restrict the vertical tilt of the process unit 65, and the process unit 65 is guided forward while maintaining a horizontal posture. Is done. When the center of gravity of the process unit 65 reaches the front of the position of the fulcrum part 61, the process part 65 receives a rotational moment in the clockwise direction around the fulcrum part 61, and the upper guide wall 58 rotates. The upward load received from the supported portion 66 by the moment is supported.

  Then, as shown in FIG. 8, when the process unit 65 is pulled out to a position where almost the entire unit housing 50 is exposed to the outside of the opening 2 </ b> A, the locking portion 69 of the process unit 65 is moved to the tip of the stopper 68. 68A is engaged, and the drawing operation of the process unit 65 is restricted.

  When removing the process unit 65 from the main casing 2 from the state shown in FIG. 8, the tip 68 </ b> A of the stopper 68 is lifted to release the engagement with the locking unit 69. Then, as shown in FIG. 9, while pulling the process portion 65 forward, the process portion 65 is slightly lifted so that the supported portion 66 exceeds the fulcrum portion 61, so that the process portion 65 is brought into contact with the main casing 2. It is withdrawn from. At this time, both the supported portion 66 and the fulcrum portion 61 are rotatable, and the outer diameter of the supported portion 66 is larger than the outer diameter of the fulcrum portion 61 (the center of the supported portion 66 is the fulcrum). Therefore, the supported portion 66 can easily get over the fulcrum portion 61.

<Embodiment 3>
Next, Embodiment 3 of the present invention will be described with reference to FIGS.
In the following description, configurations different from those in the first embodiment will be mainly described, and configurations having the same functions as those in the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.
10 is a side sectional view showing a schematic configuration of the laser printer 1B of the present embodiment, FIG. 11 is a side sectional view showing a state in which the front cover 3 is opened, and FIG. 12 is a state in the middle of pulling out the process unit 70. FIG. 13 is a side sectional view showing a state where the drawing operation of the process unit 70 is restricted.

  The laser printer 1B according to the present embodiment includes a pair of upper and lower guide walls 71 and 72 extending in the front-rear direction (lateral direction) and inclined in the front end rising direction on both the left and right sides of the process unit 70 in the main body casing 2. . That is, in the present embodiment, the drawing direction of the process unit 70 is configured to be inclined with respect to the upper surface of the transport belt 18. The upper guide wall 71 is provided with a downward guide surface 71A (corresponding to the “guide means” and “guide surface” of the present invention), and the lower guide wall 72 is provided with an upward guide surface 72A. Both guide surfaces 71A, 72A are parallel to each other and face each other with a predetermined interval. A groove 73 is formed between the guide walls 71 and 72 (both guide surfaces 71A and 72A). Furthermore, a fulcrum part 74 (corresponding to the “stopper” of the present invention) made of a rotatable rotating body is provided at the front end position of the lower guide surface 71A (front end position of the groove 73).

  On the other hand, the frame 76 of the process unit 70 is similar to the process unit 25 of the first embodiment in that a unit storage unit 77 that stores four image forming units 26, a projecting unit 78 that projects to the rear, and a projecting unit And a protruding portion 79 that partially protrudes rearward (backward in the pull-out direction) from the upper part of the rear end surface of the portion 78. In the main body casing 2, the unit housing part 77 is behind (the rear part of the projecting part 78) and is perpendicular to the protruding part 79 (the direction along the guide walls 71 and 72). The fixing device 43 is arranged at such a position as to overlap.

  Similarly to the process unit 25 of the first embodiment, the frame 76 includes a first supported portion 80 (a “locking portion” of the present invention) formed on the left and right side upper portions of the overhanging portion 78, which is a rotatable body. And a second supported portion 81 made of a rotatable rotating body is attached to both the left and right side surfaces of the protruding portion 79. Further, at the upper end portions on the left and right side surfaces of the frame 76, a plate-like shape extending in the pulling direction (that is, the extending direction of the guide walls 71 and 72) forward from the position of the first supported portion 80 and projecting outward. The fulcrum receiving wall 82 is formed. The fulcrum receiving wall 82 has a downward horizontal surface 82A extending in the front-rear direction, and a portion corresponding to the guide surface 56B of the first embodiment is not provided. Further, the fulcrum receiving wall 82 is disposed in the groove portion 73 so as not to contact the upper and lower guide surfaces 71A, 72A.

  In a state where the process unit 70 is mounted at the proper apparatus position in the main casing 2, the first supported unit 80 is positioned at the rear end of the lower guide surface 72 </ b> A as shown in FIGS. 10 and 11. The second supported portion 81 is at a position away from the groove 73. When the process part 70 is pulled forward from this state, the first supported part 80 is guided upward along the guide surface 72A, so that the process part 70 moves diagonally forward and upward, and each photosensitive drum 31 is Separated from the conveyor belt 18.

  Then, when the process unit 70 is further pulled out, as shown in FIG. 12, the second supported portion 81 enters the groove portion 73, and both the supported portions 80 and 81 are guided by the guide surfaces 71A and 71A of the guide walls 71 and 72. By abutting on 72A, the vertical tilt of the process unit 70 is restricted. In the state of FIG. 12, a rotational moment in the counterclockwise direction shown in the figure is applied to the process portion 70 around the fulcrum portion 74, and the lower guide wall 72 causes the first supported portion 80 by the rotational moment. Supports the downward load received from. When the center of gravity of the process unit 70 reaches the front of the position of the fulcrum part 74, a rotational moment in the clockwise direction shown in the figure acts on the process part 70 around the fulcrum part 74, and the upper guide wall 71 rotates. The upward load received from the second supported portion 81 is supported by the moment.

Then, as shown in FIG. 13, when the process unit 70 is pulled out to a position where almost the entire unit accommodating portion 77 is exposed to the outside of the opening 2A, the first supported portion 80 is engaged with the fulcrum portion 74. The drawer operation of the process unit 70 is restricted.
When removing the process unit 70 from the main casing 2 from the state shown in FIG. 13, as in the first embodiment, the front end of the process unit 70 is lifted and the first supported portion 80 and the fulcrum portion 74 are engaged. After releasing the match, the process unit 70 can be detached from the main casing 2 by pulling the process unit 70 forward.

<Embodiment 4>
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
In the following description, a configuration different from that of the first embodiment will be mainly described, and the same components as those of the first embodiment will be denoted by the same reference numerals and description thereof will be omitted.
14 is a side sectional view showing a state in which the process unit 90 is detached from the main casing 2, FIG. 15 is a side sectional view showing a state in which the fulcrum part 61 is in contact with the regulating unit 90, and FIGS. FIG. 19 is a side sectional view showing a state in which the first supported portion 54 is guided by the guide portion 92, and FIG.

  In the laser printer 1C of the present embodiment, a synthetic resin regulating portion 91 is provided on both the left and right sides of the process portion 90 so as to fill a space between the first supported portion 54 and the second supported portion 55. ing. The lower surface of the restricting portion 91 is a guide surface 91A that is inclined so as to be lowered at the front end when the process portion 90 is in a horizontal position (see FIG. 19). 54 and 55 are formed along the common tangent line.

  On the other hand, the main casing 2 has the above-described fulcrum part 61 and the guide part 92 (fulcrum) arranged on the rear side at the front end position (front end position of the groove part 60) of the guide surface 59A of the lower guide wall 59. The portion 61 and the “stopper” of the present invention are provided. The guide portion 92 is made of a synthetic resin and includes an inclined surface 92A that is inclined upward from the front end. The inclined surface 92 </ b> A is formed such that the rear end side is continuous with the guide surface 59 </ b> A and the front end side is substantially continuous with the upper surface of the fulcrum part 61.

  In order to mount the removed process unit 90 on the main casing 2, first, as shown in FIG. 14, the process unit 90 is moved obliquely downward and rearward while being held in a posture inclined upward toward the front end. The rear end of 90 is inserted into the opening 2 </ b> A of the main casing 2, and the left and right supported portions 54 and 55 are inserted into the groove 60 between the guide walls 58 and 59. Then, when the second supported portion 55 exceeds the fulcrum portion 61, as shown in FIG. 15, the upper surface of the fulcrum portion 61 contacts the guide surface 91A of the restricting portion 91, and the rear end side of the process portion 90 is the fulcrum portion. 61 is supported. At this time, the restricting portion 91 restricts the fulcrum portion 61 and the guide portion 92 from entering and being caught between the supported portions 54 and 55. When the process unit 90 is pushed backward from this state, the regulating unit 91 slides backward on the fulcrum 61 by the guidance of the guide surface 91A, and the first supported unit 54 moves the fulcrum 61 as shown in FIG. Ride over and contact the inclined surface 92A of the guide 92.

  Subsequently, when the front end side of the process unit 90 is lowered downward (removing the force of the hand supporting the front end side of the process unit 90), the first supported portion 54 slides back on the inclined surface 92A, and the process unit 90 90 rotates about the first supported portion 54 in the clockwise direction in the figure, and the second supported portion 55 contacts the guide surface 58A of the upper guide wall 58 as shown in FIG. Then, as shown in FIG. 18, when the first supported portion 54 comes into contact with the guide surface 59A of the lower guide wall 59, the rotation of the process portion 90 is stopped and the process portion 90 is supported in a horizontal posture. The Thus, the process portion 90 is lowered and pushed backward (back side) by the guide of the inclined surface 92A, and the second supported portion 55 surely enters the back side of the groove portion 60. Therefore, the insertion of the process part 65 becomes shallow, so that the second supported part 55 is prevented from coming out from the front end of the guide wall 58 to the front side, and the process part 90 is prevented from dropping off. The process unit 90 is pushed backward from the state of FIG. 18 (see FIG. 19). When the process unit 90 reaches a proper mounting position (not shown), the mounting of the process unit 90 is completed.

  Next, when the process unit 90 attached to the main casing 2 is pulled out, as shown in FIG. 19, the process unit 90 is pulled out horizontally by the guidance of the upper and lower guide surfaces 58A and 59A. Then, when the first supported portion 54 reaches the front end of the guide wall 59, as shown in FIG. 18, the first supported portion 54 abuts against the guide portion 92 and is locked. Be regulated.

  Then, when removing the process part 90 from the main body casing 2, the front-end part of the process part 90 is pulled up diagonally upward. Then, the first supported portion 54 moves obliquely upward and forward along the inclined surface 92A of the guide portion 92, and the process portion 90 rotates counterclockwise to be inclined to the front end (see FIG. 17 and FIG. 16). When the front end of the process part 90 is further lifted from this state, the first supported part 54 passes over the fulcrum part 61 and the guide surface 91A of the restricting part 91 rides on the upper surface of the fulcrum part 61 as shown in FIG. Therefore, the process unit 90 can be detached from the main casing 2 as shown in FIG. 14 by moving the process unit 90 obliquely upward while holding the rear end side of the process unit 90.

  As described above, according to the present embodiment, since the process unit 90 can be detached from the apparatus main body by moving the process unit 90 upward from the pulled-out direction, the process unit 90 can be easily removed. Further, if the drawing direction and the detaching direction of the process unit 90 are the same, the process unit 90 may be mistakenly pulled out when being pulled out. However, in this configuration, the drawing direction and the detaching direction of the process unit 90 are different. Therefore, it is possible to prevent the process unit 90 from being accidentally extracted.

  Further, when the process unit 90 is mounted on the main casing 2, the process unit 90 (first supported unit 54) is lowered by guiding the first supported unit 54 along the inclined surface 92 </ b> A of the guide unit 92. And it is pushed to the back side. Thereby, since the process part 90 is stably supported without turning over, the process part 90 can be mounted smoothly.

  Further, since the first supported portion 54, the guide portion 92, and the fulcrum portion 61 can be unlocked by rotating the front end side of the process portion 90 so as to be lifted, the process portion 90 can be easily removed from the main body casing 2. Can be removed.

  Furthermore, since a restricting portion 91 that restricts the guide portion 92 and the fulcrum portion 61 from entering is provided between the pair of supported portions 54 and 55, the pair of supported portions 54 is attached when the process portion 90 is attached or detached. , 55 is prevented from being caught between the guide portion 92 and the fulcrum portion 61, and the operation can be performed smoothly.

  Further, when the process unit 90 is mounted or detached, the fulcrum unit 61 is guided by the guide surface 91A provided in the regulating unit 91, so that the work can be performed smoothly.

<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, the present invention is applied to a direct transfer type laser printer that performs transfer from an image carrier (photosensitive drum) to a recording medium (paper). The present invention can also be applied to an intermediate transfer type laser printer that transfers to a recording medium via an intermediate transfer member (intermediate transfer belt or intermediate transfer drum).
(2) In each of the above embodiments, a printer using four color toners of yellow, magenta, cyan, and black is exemplified. However, the present invention is not limited to this. For example, a printer that uses two color toners of red and black, or six colors. The present invention can be applied to a toner using the above toner.

(3) In each of the above-described embodiments, only the developing cartridge (developing device) of the image forming unit is detachably held with respect to the frame of the process unit. However, according to the present invention, the image forming unit Other components (photosensitive drum, charger, etc.) may be detachable from the frame.
(4) In each of the above embodiments, a pair of upper and lower guide walls are provided on the left and right sides, and the guide surfaces provided on each of the guide walls face each other. However, according to the present invention, for example, the guide walls It is possible to provide only one on both the left and right sides, and use the upper and lower surfaces of the guide wall as guide surfaces, and a pair of supported parts provided on the process part (drawer part) side abut on the upper and lower guide surfaces. good.

(5) In each of the above embodiments, the fixing device is disposed so as to overlap the lower side with respect to the protruding portion protruding on the upper rear surface of the process portion (drawer portion). According to the invention, for example, the fixing device may be arranged so as to overlap the upper side of the protruding portion, or the fixing device may be arranged to overlap between the protruding portions protruding to the left and right sides. Also good.
(6) In the first and second embodiments, the front end and the rear end of the process unit are simultaneously lifted and separated from the transport belt as the process unit (drawer unit) is pulled out. According to the present invention, the front end and the rear end of the process unit may be lifted at different times. In this case, the operating force for lifting the process unit is higher than when both ends are lifted simultaneously. Can be reduced.

1 is a side sectional view showing a schematic configuration of a laser printer according to a first embodiment. Side sectional view showing a state where the front cover is opened Side sectional view showing the process part in the process of being pulled out Side sectional view showing a state in which the drawing operation of the process unit is restricted Side sectional view showing the process part in the middle of removal Sectional drawing which shows the state which open | released the front cover in the laser printer which concerns on Embodiment 2. Side sectional view showing the process part in the process of being pulled out Side sectional view showing a state in which the drawing operation of the process unit is restricted Side sectional view showing the process part in the middle of removal Sectional drawing which shows schematic structure of the laser printer which concerns on Embodiment 3. FIG. Side sectional view showing a state where the front cover is opened Side sectional view showing the process part in the process of being pulled out Side sectional view showing a state in which the drawing operation of the process unit is restricted Sectional drawing which shows the state which detached | separated the process part from the main body casing in the laser printer which concerns on Embodiment 4. Side sectional view showing a state where the fulcrum part is in contact with the regulating part Side sectional view showing a process in which the first supported part is guided by the guide part Side sectional view showing a process in which the first supported part is guided by the guide part Side sectional view showing a process in which the first supported part is guided by the guide part Side sectional view showing a state in which the process part is in the middle of withdrawal

1, 1A, 1B, 1C ... Laser printer (image forming apparatus)
2 ... Main body casing (device main body)
4. Paper (recording medium)
18 ... Conveying belts 25, 65, 70, 90 ... Process part (drawer part, process cartridge)
26... Image forming unit 43... Fixing device 50 and 77... Unit housing portion 53 and 79.
55, 81 ... second supported part (supported part)
56, 82 ... fulcrum receiving wall 56B ... guide surface (guide means)
58, 59, 71, 72 ... guide walls 58A, 59A, 71A ... guide surface 59B ... guide surface (guide means)
61 ... fulcrum (stopper)
66 ... supported portion 68 ... stopper 69 ... locking portion 72A ... guide surface (guide means, guide surface)
74 ... fulcrum portion 91 ... regulating portion 91A ... guide surface 92 ... guide portion (stopper)
92A ... Inclined surface

Claims (16)

An apparatus body having a guide wall;
A plurality of image forming units for forming an image on a recording medium;
A drawer portion provided so as to be capable of being pulled out along the guide wall in the pulling direction with respect to the apparatus main body;
A belt disposed below the drawer portion,
The drawer is
A unit housing portion housing the plurality of image forming units;
A protruding portion protruding upstream in the pull-out direction with respect to the unit accommodating portion;
A first supported portion;
Wherein in the pull-out direction than the first supported portion provided on the upper stream side, and a second supported portion provided on the projecting portion,
The guide wall is
A downwardly extending surface extending in the pull-out direction, the first guide surface with which the second supported portion abuts during the pull-out operation of the pull-out portion;
An upward surface provided so as to face the first guide surface in parallel with a predetermined interval, and the first supported portion comes into contact with the drawer during the drawer operation. A second guide surface that regulates tilting of the portion in the vertical direction;
An upward surface that is continuous with the downstream end of the second guide surface in the pull-out direction and is inclined upward toward the downstream end. When the pull-out portion is attached to the apparatus main body, the first supported portion An image forming apparatus comprising: a guide surface that contacts and guides the first supported portion so that the drawer portion is gradually separated from the belt as the drawer portion is pulled out.   2. The image forming apparatus according to claim 1, wherein the drawer part is configured to be detachable from the apparatus main body by moving the drawer part upward in the drawing direction in a state where the drawer part is pulled out from the apparatus main body. apparatus. A guide portion having an inclined surface rising to the downstream end that guides the first supported portion when the drawer portion is attached to the apparatus main body is formed at a downstream end position in the pull-out direction of the guide wall. The image forming apparatus according to claim 2.     A fixing device is disposed in the apparatus main body at a position that is upstream of the unit accommodating portion in the pulling direction and overlaps the protruding portion in a direction perpendicular to the pulling direction. The image forming apparatus according to any one of claims 1 to 3.     The at least one of the first supported portion and the second supported portion is composed of a rotating body that can rotate by contact with the first guide surface or the second guide surface. The image forming apparatus according to claim 4. The drawer portion includes a locking portion,
The said apparatus main body is provided with the stopper which controls the drawer | drawing-out operation | movement of the said drawer | drawing-out part by latching with the said latching | locking part at the time of the said drawer | drawing-out part pulling out. An image forming apparatus according to claim 1.   The image forming apparatus according to claim 6, wherein the drawer portion is detachable from the apparatus main body by releasing the engagement between the engagement portion and the stopper.     8. The image according to claim 7, wherein the pulling portion is configured to be able to release the locking between the locking portion and the stopper by rotating so as to lift the downstream end side in the pulling direction. Forming equipment.     The image forming apparatus according to claim 6, wherein the first supported portion or the second supported portion also serves as the locking portion.   10. A restricting portion for restricting entry of the stopper is provided between the first supported portion and the second supported portion. Image forming apparatus.   The image forming apparatus according to claim 10, wherein the restricting portion includes a guide surface that guides the stopper when the drawer portion is attached or detached. The drawer portion includes a fulcrum receiving wall extending along the drawer direction,
The image forming apparatus according to claim 1, wherein the apparatus main body includes a fulcrum portion that supports the drawer portion by placing the fulcrum receiving wall on an upper surface.   The image forming apparatus according to claim 12, wherein the fulcrum portion includes a rotating body that is rotatable by contact with the fulcrum receiving wall.   The image forming apparatus according to claim 12, wherein the fulcrum portion also serves as the stopper.   The image forming apparatus according to claim 12, wherein the fulcrum receiving wall is disposed between the first guide surface and the second guide surface.   The image forming apparatus according to claim 1, wherein the belt is a conveyance belt that conveys a recording medium to each of the image forming units.

Images