JP2005283881A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus in which a transfer roller unit can be attached to a transfer position without damaging the transfer roller unit. <P>SOLUTION: In process cartridge guide grooves 61, on both facing walls in a passage 2b, transfer roller guide grooves 65 are formed which are further deepened toward the outside direction in the width direction of the guide grooves 61. These transfer roller guide grooves 65 are formed to incline downward from an opening part 2c toward an upper position of the transfer position X , bent directly downward toward the transfer position X from the upper position and are formed to be the same width over the whole length. Then, the transfer guide grooves 65 are set so that the transfer roller 26 is supported by having each end part 26c of a roller shaft 26a inserted in an orthogonal state to the direction of insertion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus in which a transfer roller unit for transferring a toner image formed on an image carrier to a recording medium is detachably mounted.

Some image forming apparatuses have a configuration in which a process cartridge that is integrally provided with a transfer roller and an image carrier can be attached to and detached from the apparatus body. There is a configuration in which the roller can be attached to and detached from the apparatus body as a transfer roller unit separate from the process cartridge and can be replaced independently.
Here, when the transfer roller unit is mounted on the apparatus main body, it is usually necessary to insert the transfer roller unit into an inside from an opening formed in the apparatus main body and mount it at a predetermined transfer position located on the inner side. Transfer rollers are generally weak in mechanical strength, and scratches, fingerprints, etc. on the surface may affect the transfer performance, leading to degradation in image formation quality. It is necessary to insert the transfer roller unit to the transfer position so that the parts do not come into contact with each other.

In the following Patent Document 1, there is provided a configuration in which a transfer guide that supports the transfer roller is provided, and the state of the transfer guide is changed to displace the transfer roller between a state where it is installed on the transfer bearing and a state where it is detached from the transfer bearing. It is disclosed.
JP 2001-201960 A

  However, in the configuration of Patent Document 1, it is necessary to operate the transfer guide on the back side where the visibility near the transfer position is poor. After all, when the transfer roller unit is inserted to the back side, there is another surface on the surface. There arises a problem that the internal parts of the contact.

  The present invention has been completed based on the above circumstances, and an object thereof is to provide an image forming apparatus that can be mounted at a transfer position without damaging the transfer roller unit.

  As means for achieving the above object, an image forming apparatus according to the invention of claim 1 includes a transfer roller unit for transferring a toner image formed on an image carrier to a recording medium, and an opening. The transfer roller unit inserted into the opening through the opening includes an apparatus main body mounted at a transfer position at which the toner image can be transferred to a recording medium, and the opening in the apparatus main body. Each of the opposing walls of the passage path through which the transfer roller unit passes from the side to the transfer position engages with an end of the transfer roller unit, and the transfer roller unit is moved from the opening side to the transfer position. A guide engaging portion capable of guiding is formed.

<Glossary>
In the present invention, the “image carrier” includes not only a photosensitive drum (photosensitive member) but also an intermediate transfer member.
The “image forming apparatus” includes not only a copying machine such as a laser printer but also a facsimile machine and a multifunction machine having a printer function and a scanner function.
The “transfer roller unit” may be a transfer roller unit including not only the transfer roller alone but also the transfer roller and a holder for rotatably holding the transfer roller at both ends.
“End of transfer roller unit” means the end of the transfer roller shaft when the transfer roller unit is a single transfer roller, the end of the holder when the transfer roller unit is the transfer roller unit, or the holder It may be a protruding portion (including the end portion of the shaft body of the transfer roller) protruding from the end surface.
The “guide engaging portion” includes, for example, a guide groove or a step portion that can be engaged with the end portion of the transfer roller unit.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the transfer roller unit is guided while the axial direction of the transfer roller is orthogonal to the insertion direction from the opening, and the transfer is performed. It is mounted at a position.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the guide engaging portion is inclined downward from the opening side toward the transfer position. To do.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the guide of the transfer roller unit is provided between an end of the transfer roller unit and the guide engaging portion. In the process, a dropout prevention mechanism is provided for maintaining the engaged state between the end portion and each guide engaging portion.

  According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the guide engaging portion includes a guide groove or a guide step portion that engages with a tip portion of an end portion of the transfer roller unit. The drop-off prevention mechanism is in contact with the guide groove or the peripheral wall of the guide step portion of the opposing wall, and an angle formed by the longitudinal direction of the transfer roller unit and the guide direction of the transfer roller unit by the guide engaging portion. It is the structure which provided the regulating member which regulates within the predetermined range at the edge part of the said transfer roller unit, respectively.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the apparatus main body has a process cartridge having the image carrier inserted therein from the opening. The transfer roller unit mounted at the transfer position is configured to be mounted at an image forming position where the transfer roller and the image carrier can come into contact with each other, and the guide engaging portion is formed only at the end of the transfer roller unit. In addition, it is configured to engage with the end portion of the process cartridge and guide the process cartridge from the opening side to the image forming position.
<Glossary>
The “end of the process cartridge” includes, for example, an end of a frame of the process cartridge, an end of a rotating shaft such as an image carrier and a developing roller that respectively protrude from the end surface of the frame.

  According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the apparatus main body has a process cartridge having the image carrier inserted therein from the opening. The transfer roller unit mounted at the transfer position is configured to be mounted at an image forming position where the transfer roller and the image carrier can come into contact with each other. Each of the opposite walls of the path is formed with a guide engaging portion for a process cartridge that engages with an end portion of the process cartridge and can guide the process cartridge from the opening side to the image forming position. A configuration in which the guide engaging portion for the transfer roller unit cannot be engaged with the end portion of the process cartridge, and / or the guide engagement for the process cartridge There, characterized in that an end portion and engageable non structure of the transfer roller unit.

<Glossary>
The “non-engageable configuration” includes, for example, the following configuration.
(A) The length between both ends of the transfer roller unit is different from the length between both ends of the process cartridge, and the separation distance of the guide engaging portion for the transfer roller unit and the guide engagement for the process cartridge correspond to each. The structure where the separation distance of a part differs.
(B) The engagement shape and size of the end portion of the transfer roller unit and the guide engagement portion for the transfer roller unit and the engagement shape and size of the end portion of the process cartridge and the guide engagement portion for the process cartridge are mutually Different configuration.
Further, the “guide engaging portion for the process cartridge” includes, for example, a guide groove or a step portion that can be engaged with the end portion of the process cartridge.

  According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the guide engaging portion for the process cartridge is inclined downward from the opening side toward the image forming position. And

  According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the sixth to eighth aspects, the axial direction of the image carrier of the process cartridge is orthogonal to the insertion direction from the opening. It is guided in a state and is mounted at the image forming position.

  According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the sixth to ninth aspects, the transfer roller unit is inserted into the transfer roller unit from behind in the guide process of the process cartridge. A part of the process cartridge is configured to be in contact with the process cartridge.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first to tenth aspects, the transfer roller unit is a single transfer roller, and the end portion is a roller shaft body of the single transfer roller. It is an end part.

<Invention of Claims 1 and 2>
According to this configuration, since the transfer roller unit is guided from the opening to the transfer position by the guide engaging portion that engages with each end portion thereof, the transfer roller unit is replaced when the transfer roller unit is exchanged. It is possible to regulate contact with other components inside the apparatus main body.

<Invention of Claim 3>
According to this configuration, since the guide engaging portion is inclined downward from the opening side toward the transfer position, each end of the transfer roller unit is engaged with the opening side of the guide engaging portion. Then, the transfer roller unit is guided to the transfer position by its own weight, and the convenience of the replacement work is further enhanced.

<Invention of Claim 4>
According to this configuration, in the guiding process of the transfer roller unit, the drop prevention mechanism is provided to maintain the engagement state between each end portion and each guide engaging portion. It is possible to easily guide while maintaining the posture that can be mounted at the position.

<Invention of Claim 5>
According to this configuration, the regulating member is provided at each end of the transfer roller unit, and in the guiding process, the transfer roller unit is moved in the longitudinal direction by the contact between the regulating member and the peripheral wall of the guide groove or the guide stepped portion. Guide is performed while the angle between the direction (the axial direction of the transfer roller) and the guide direction of the transfer roller unit by the guide engaging portion is regulated within a predetermined range.
As described above, with this configuration, the restriction member is provided at each end of the transfer roller unit, and the transfer roller is guided in a state of being tilted by a predetermined range or more. Can be prevented from falling off from the guide engaging portion.

<Inventions of Claims 6 and 9>
According to this configuration, the guide engaging portion engages with not only the transfer roller unit but also the end of the process cartridge, and can guide the process cartridge from the opening side to the image forming position. In other words, the transfer roller unit and the process cartridge are guided to the respective mounting positions (transfer position, image forming position) by a common guide engaging portion, so that the transfer roller unit and the process cartridge are separately guided. Compared to the configuration in which the engaging portion is provided, the space for forming the guide engaging portion can be saved.

<Inventions of Claims 7 and 9>
According to this configuration, the guide engaging portion for the transfer roller unit cannot be engaged with the end of the process cartridge, and / or the guide engaging portion for the process cartridge is engaged with the end of the transfer roller unit. The configuration is impossible. Accordingly, it is possible to prevent the transfer roller unit or the process cartridge from being engaged with the guide engaging portion different from the dedicated guide engaging portion and mounted at the mounting position.
Normally, since the transfer roller unit is attached to the apparatus main body before the process cartridge, at least the guide engaging portion for the process cartridge may be configured so that it cannot be engaged with the end portion of the transfer roller unit. desirable.

<Invention of Claim 8>
According to this configuration, since the guide engaging portion for the process cartridge is inclined downward from the opening side toward the image forming position, the end portion of the process cartridge is engaged with the opening side of the guide engaging portion. If combined, the process cartridge is guided to the image forming position by its own weight, and the convenience of the replacement work is further increased.

<Invention of Claim 10>
According to this configuration, for example, even when the transfer roller unit remains in the middle of the passage path from the opening side to the transfer position, the transfer roller unit is pushed by the process cartridge inserted later and transferred. You can guide to the position. Therefore, the transfer roller unit can be reliably guided to the transfer position even when the guide engaging portion is formed horizontally from the opening side to the transfer position or inclined upward.

<Invention of Claim 11>
When the transfer roller unit is a single transfer roller without a holder, the entire roller surface of the transfer roller is exposed to the outside, and the operator's hand touches the roller surface or contacts other parts inside the device body. Is more likely to do. Therefore, it is particularly useful to apply the above inventions to such a configuration.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
1. Configuration of the Present Embodiment FIG. 1 is a side sectional view of an essential part showing an embodiment of a laser printer as an image forming apparatus of the present invention. In FIG. 1, a laser printer 1 includes a feeder unit 4 for feeding a sheet 3 as a recording medium in a main body casing 2 and an image formation for forming a predetermined image on the fed sheet 3. Unit 5 etc. are provided.

  Here, in this embodiment, as will be described later, the process cartridge 12 and the transfer roller 26 are separated from each other, and these are the apparatus main body 1a of the laser printer 1 (the above-mentioned process of the configuration of the laser printer 1). The configuration in which the cartridge 12 and the transfer roller 26 are removed can be attached to and detached from each other independently. In addition, an opening / closing door 2a is provided on one side of the main casing 2 (the right side in FIG. 1) so as to be rotatable around the lower end (see FIGS. 1 and 3). When the opening / closing door 2a is opened, a passage 2b is formed to allow the process cartridge 12 and the transfer roller 26 to be inserted to a transfer position X and an image forming position Y described later. The opening end of the passage 2b corresponds to the opening of the present invention (hereinafter referred to as “opening 2c”).

(1) Configuration of Feeder Unit The feeder unit 4 includes a paper feed tray 43 that is detachably attached to the bottom of the main body casing 2, a paper pressing plate 6 provided in the paper feed tray 43, and a paper feed tray. The sheet feeding roller 7 and the sheet feeding pad 8 are provided above one end of the sheet 43, and the registration roller 9 is provided downstream of the sheet feeding roller 7 in the conveyance direction of the sheet 3.

  The sheet pressing plate 6 can stack the sheets 3 in a stacked manner, and is supported so that the end far from the sheet feeding roller 7 can swing, and the near end rotates in the vertical direction. It is made possible and is urged upward by a spring (not shown) from the back side. Therefore, the sheet pressing plate 6 is rotated downward against the urging force of the spring with the end portion far from the sheet feeding roller 7 as a fulcrum as the amount of stacked sheets 3 increases. The paper feed roller 7 and the paper feed pad 8 are arranged to face each other, and the paper feed pad 8 is pressed toward the paper feed roller 7 by a spring 10 provided on the back side of the paper feed pad 8. .

  The uppermost sheet 3 on the sheet pressing plate 6 is pressed toward the sheet feeding roller 7 by a spring (not shown) from the back side of the sheet pressing plate 6, and the sheet feeding roller 7 and the sheet feeding are rotated by the rotation of the sheet feeding roller 7. After being sandwiched between the pads 8, the sheets are fed one by one. The fed paper 3 is sent to a registration roller 9 by a paper feed roller 7. The registration roller 9 is composed of two rollers, a driving roller 44 provided on the main body casing 2 side and a driven roller 45 provided on the process cartridge 12 side, which will be described later. 3 is sandwiched between the driving roller 44 and the driven roller 45, and is sent to the image forming unit 5 after a predetermined registration.

(2) Configuration of Image Forming Unit The image forming unit 5 includes a scanner unit 11, a process cartridge 12, a transfer roller 26, a fixing unit 13, and the like.
(A) Configuration of Scanner Unit The scanner unit 11 is provided in the upper part of the main body casing 2 and has a laser light emitting unit (not shown), a polygon mirror 14 that is rotationally driven, lenses 15 and 16, and reflecting mirrors 17 and 18. , 19, and the like, and a laser beam based on predetermined image data emitted from the laser light emitting unit, as indicated by a chain line, a polygon mirror 14, a lens 15, reflecting mirrors 17 and 18, a lens 16, and a reflecting mirror 19. Are passed or reflected in this order to irradiate the surface of a photosensitive drum 21 (the “image carrier” of the present invention) of the process cartridge 12 to be described later by high-speed scanning.

(B) Configuration of Process Cartridge Next, the process cartridge 12 will be described with reference to FIG. As shown in the figure, the process cartridge 12 does not include the transfer roller 26, and the transfer roller 26 is separated from the process cartridge 12 as the transfer roller 26. That is, the transfer roller 26 can be attached to and detached from the apparatus main body 1a independently of the process cartridge 12.

  FIG. 2 is an enlarged side sectional view showing the process cartridge 12. In the figure, a process cartridge 12 is disposed below the scanner unit 11 and is detachably mounted on the main body casing 2, and a photosensitive drum 21, a developing cartridge 36, and a scorotron charger 25. Etc. The developing cartridge 36 is detachably attached to the drum cartridge 20 and includes a developing roller 22, a layer thickness regulating blade 23, a supply roller 24, a toner box 27, and the like.

  The toner box 27 is filled with a positively charged non-magnetic one-component toner as a developer. Examples of the toner include polymerizable monomers such as styrene monomers such as styrene, and acrylic monomers such as acrylic acid, alkyl (C1 to C4) acrylate, and alkyl (C1 to C4) methacrylate. Polymerized toners obtained by copolymerization by a known polymerization method such as suspension polymerization are used. Such a polymerized toner is spherical and has very good fluidity. Such a toner is blended with a colorant such as carbon black, wax, and the like, and an additive such as silica is added to improve fluidity. The particle diameter is about 6 to 10 μm.

  The toner in the toner box 27 is agitated by an agitator 29 supported by a rotating shaft 28 provided at the center of the toner box 27 and discharged from a toner supply port 30 opened at a side portion of the toner box 27. . Note that a toner remaining amount detection window (not shown) is provided on the side wall of the toner box 27 and is cleaned by a cleaner 39 supported by the rotary shaft 28.

  A supply roller 24 is disposed at a side position of the toner supply port 30 so as to be rotatable in the direction of the arrow (counterclockwise), and the developing roller 22 faces the supply roller 24 in the direction of the arrow ( It is arranged to be rotatable counterclockwise. The supply roller 24 and the developing roller 22 are in contact with each other in a state where each of them is compressed to some extent.

  The supply roller 24 has a metal roller shaft covered with a roller made of a conductive foam material. The developing roller 22 has a metal roller shaft covered with a roller made of a conductive rubber material. More specifically, the roller portion of the developing roller 22 has a urethane rubber or silicone rubber coating layer containing fluorine on the surface of a roller body made of conductive urethane rubber or silicone rubber containing carbon fine particles. It is covered. A predetermined developing bias is applied to the developing roller 22 with respect to the photosensitive drum 21.

  In addition, a layer thickness regulating blade 23 is disposed in the vicinity of the developing roller 22. The layer thickness regulating blade 23 includes a blade body 37 made of a metal leaf spring material, and a pressing portion 38 having a semicircular cross section made of an insulating silicone rubber provided at the tip of the blade body 37. The end of the blade body 37 opposite to the pressing portion 38 is supported by the developing cartridge 36 near the developing roller 22, and the pressing portion 38 is pressed against the developing roller 22 by the elastic force of the blade body 37. It is configured as follows.

  The toner discharged from the toner supply port 30 is supplied to the developing roller 22 by the rotation of the supplying roller 24. At this time, the toner is positively frictionally charged between the supplying roller 24 and the developing roller 22, and further developed. As the developing roller 22 rotates, the toner supplied onto the roller 22 enters between the pressing portion 38 of the layer thickness regulating blade 23 and the developing roller 22, where the toner is more sufficiently frictionally charged and constant. It is carried on the developing roller 22 as a thin layer.

  The photosensitive drum 21 is disposed at a side position of the developing roller 22 so as to be rotatable in the arrow direction (clockwise) in a state of facing the developing roller 22 with a predetermined interval. The photosensitive drum 21 is formed of a positively chargeable photosensitive layer having a drum body grounded and a surface portion made of polycarbonate or the like.

  The scorotron charger 25 is disposed above the photosensitive drum 21 at a predetermined interval so as not to contact the photosensitive drum 21. The scorotron charger 25 is a positively charged scorotron charger that generates corona discharge from a charging wire such as tungsten, and is configured to uniformly charge the surface of the photosensitive drum 21 to a positive polarity. ing.

  The surface of the photosensitive drum 21 is uniformly positively charged by the scorotron charger 25 and then exposed by high-speed scanning of the laser beam from the scanner unit 11 to form an electrostatic latent image based on predetermined image data. Is done. Next, the electrostatic latent image formed on the surface of the photosensitive drum 21 when the positively charged toner carried on the developing roller 22 comes into contact with the photosensitive drum 21 by the rotation of the developing roller 22. That is, the surface of the photosensitive drum 21 that is uniformly positively charged is supplied to a portion of the photosensitive drum 21 that is exposed to a laser beam and the potential of which is lowered, and is selectively carried to be visualized. Development (formation of a toner image) is achieved.

  A brush support plate 51 that extends obliquely upward is integrally formed from the front lower end of the drum cartridge 20. A cleaning brush 52 is provided on the brush support plate 51. The cleaning brush 52 includes a brush holder 53 and a brush 54. The brush holder 53 is provided between the brush support plates 51, and the brush 54 is provided on the brush holder 53 so as to face the photosensitive drum 21. The brush 54 is made of a conductive member, and is applied with a bias voltage from a high voltage power supply circuit (not shown) provided in the apparatus main body 1a to remove paper dust adhering to the photosensitive drum 21.

(C) Configuration of Transfer Roller Next, the transfer roller 26 will be described. The transfer roller 26 is configured by covering a metal roller shaft 26a with a roller 26b made of a conductive rubber material, leaving both ends thereof. In the present embodiment, the pair of ends 26c and 26c of the roller shaft 26a protruding from the end surface of the roller 26b of the transfer roller 26 (the “end portion of the transfer roller unit” of the present invention) plays a role of preventing dropping. The annular members 40, 40 (see FIGS. 4 and 5) are fitted. The annular members 40 will be described in detail later. A predetermined transfer bias is applied to the transfer roller 26 with respect to the photosensitive drum 21. Therefore, the visible image carried on the photosensitive drum 21 is transferred to the sheet 3 while the sheet 3 passes between the photosensitive drum 21 and the transfer roller 26.

(D) Configuration of Fixing Unit As shown in FIG. 1, the fixing unit 13 is disposed on the downstream side of the process cartridge 12, and includes a heating roller 32, a pressing roller 31 pressed against the heating roller 32, and these heating rollers 32. And a conveyance roller pair 33 provided on the downstream side of the pressing roller 31. The heating roller 32 is made of a metal and has a halogen lamp for heating, and the toner transferred onto the paper 3 in the process cartridge 12 is passed while the paper 3 passes between the heating roller 32 and the pressing roller 31. Then, the sheet 3 is transported to the paper discharge path 56 by the transport roller 33. The paper 3 sent to the paper discharge path 56 is sent to the paper discharge roller 34 and is discharged onto the paper discharge tray 35 by the paper discharge roller 34.

  In the laser printer 1, the toner remaining on the photosensitive drum 21 after being transferred onto the sheet 3 by the transfer roller 26 is recovered by the developing roller 22, and the residual toner is recovered by a so-called cleanerless system. . If the toner remaining on the photosensitive drum 21 is collected by such a cleaner-less method, there is no need to provide a cleaning device such as a blade or a waste toner storage unit, so that the configuration of the device is simplified, the size is reduced, and the cost is reduced. Can be achieved.

(3) Configuration for Guiding Transfer Roller and Process Cartridge As shown in FIGS. 1 and 3, when the opening / closing door 2a of the apparatus main body 1a is opened, it is conveyed from the feeder unit 4 to the lower back side of the passage 2b. The conveyance path 57 for the incoming paper 3 is exposed. Hereinafter, the direction from the opening / closing door 2a (opening 2c) toward the back side of the passage 2b (the direction from the right side to the left side in the figure) will be described as the front of the insertion direction.

In the present embodiment, the process cartridge 12 is inserted through the opening 2c in a state where the axial direction (longitudinal direction) of the photosensitive drum 21 is orthogonal to the insertion direction and is mounted at the image forming position Y. It has become. Here, the image forming position Y refers to a position where the photosensitive drum 21 faces and contacts the transfer roller 26 mounted at the transfer position X, which will be described below, with the conveyance path 57 interposed therebetween.
On the other hand, the transfer roller 26 is configured to be inserted from the opening 2c and mounted at the transfer position X in a state where the axial direction (longitudinal direction) of the transfer roller 26 is also orthogonal to the insertion direction. Here, the transfer position X refers to a position where the transfer roller 26 is opposed to and in contact with the photosensitive drum 21 of the process cartridge 12 mounted at the image forming position Y with the conveyance path 57 interposed therebetween.

(A) Configuration for guiding a process cartridge In each of a pair of opposing walls (only the opposing wall 60 on the right side is shown in FIG. 3) facing each other in the width direction of the passage 2b (the depth direction in FIG. 3), A process cartridge guide groove 61 that is recessed outward in the width direction is formed. The process cartridge guide groove 61 extends so as to gradually become narrower from the opening 2c toward the front side in the insertion direction. In the process cartridge 12 inserted from the opening 2c, for example, the end of the roller shaft 21a of the photosensitive drum 21 protruding from both side surfaces thereof is guided by the process cartridge guide groove 61, and as shown in FIG. The position Y is positioned and held.

  Note that three electrodes 62 connected to, for example, a high-voltage power source (not shown) provided on the apparatus main body 1a side are exposed at a front portion of the process cartridge guide groove 61 in the right facing wall 60 of the passage 2b. ing. These are connected to an electrode (not shown) connected to the cleaning brush 52 protruding from the right side surface of the process cartridge 12 and the grid electrode of the scorotron charger 25 with the process cartridge 12 mounted at the image forming position Y. An electrode (not shown) and an electrode (not shown) connected to the charging wire of the scorotron charger 25 are elastically contacted, respectively, and serve to apply a bias voltage to the cleaning brush 52 and the scorotron charger 25.

(B) Configuration for guiding the transfer roller The transfer path X below the transport path 57 of the paper 3 (the position below the photosensitive drum 21 of the process cartridge 12 mounted at the image forming position Y) is in the transport path. An accommodation groove 63 extending so as to cross 57 is formed. The transfer roller 26 guided by the transfer roller guide groove 65 described below is rotatably mounted with its end portion 26c being supported by a bearing portion 64 in the accommodation groove 63.

  Also, as shown in FIG. 3, the transfer roller guide groove 65 further recessed outward in the width direction in the process cartridge guide groove 61 on both opposing walls 60 of the passage 2b (see “ Guide engaging portions (for the transfer roller unit) ”) are formed. The transfer roller guide groove 65 is inclined downward from the opening 2c toward the upper position of the transfer position X, bent downward from the upper position toward the transfer position X, and has the same width over the entire length. It is formed to become. 4 and 5, the transfer roller guide groove 65 is set so that the end 26c of the roller shaft 26a is inserted and supported in a state where the transfer roller 26 is orthogonal to the insertion direction. Yes.

  In the present embodiment, the lower peripheral portion 2e connected to the lower surface of the transfer roller guide groove 65 is located on the side wall of the opening 2c, rather than the upper portion 2d connected to the upper surface of the transfer roller guide groove 65. It has a stepped shape protruding toward the opening 2c. Therefore, there is an advantage that the operation of placing the end portion 26c of the transfer roller 26 so as to be inserted into the guide groove 65 for the transfer roller is easy.

(C) Annular Member In the present embodiment, a pair of annular members 40 and 40 (the “regulatory member” of the present invention) disposed on the end 26c of the roller shaft 26a of the transfer roller 26 are provided. In the annular member 40, a large-diameter portion 41 and a small-diameter portion 42 having different outer diameters are integrally formed concentrically and fitted with a predetermined clearance to the roller shaft 26a of the transfer roller 26. It has an annular shape with a possible inner diameter.

2. As shown in FIG. 4, first, the end 26c of the roller shaft 26a of the transfer roller 26 is inserted into the guide groove 65 for the transfer roller. It mounts on the edge part 26c by the side of the opening part 2c. At this time, each annular member 40 is positioned between the end surface of the roller 26 b of the transfer roller 26 and the upper and lower peripheral wall surfaces of the transfer roller guide groove 65 when the transfer roller 26 is placed in the transfer roller guide groove 65. And it is made to penetrate so that the large diameter part 41 may be located in the said surrounding wall surface side. When the hand is released, the transfer roller 26 moves downward along the inclination of the transfer roller guide groove 65 by its own weight (in the direction of the white arrow in FIG. 4). Then, the end of the roller shaft 26a is guided to the transfer position X by the transfer roller guide groove 65 (see FIG. 3).

Here, in the process of guiding the transfer roller 26, there is a possibility that the axial direction of the transfer roller 26 is guided in a state where it is inclined with respect to the direction orthogonal to the insertion direction. However, in the present embodiment, even if the transfer roller 26 is about to tilt due to the annular member 40 serving as a drop-off preventing mechanism, the large diameter portion 41 of the annular member 40 and the peripheral wall surface of the transfer roller guide groove 65 contact each other. It is regulated and can be guided to the transfer position X while maintaining a posture in a direction substantially orthogonal to the insertion direction.
Thereafter, the process cartridge 12 is mounted from the opening 2c. As a result, the photosensitive drum 21 and the transfer roller 26 positioned below the photosensitive drum 21 come into contact with each other while being pressed by the weight of the process cartridge 12.

3. Effects of this embodiment (1) According to this embodiment, the transfer roller 26 is guided from the opening 2c to the transfer position X by the transfer roller guide groove 65 that engages with each end portion 26c. When the transfer roller 26 is exchanged, the transfer roller 26 can be restricted from contacting other parts (such as the scanner unit 11) inside the apparatus main body 1a.
(2) Since the transfer roller guide groove 65 is inclined downward from the opening 2c side toward the transfer position X, each end 26c of the transfer roller 26 is opened to the transfer roller guide groove 65. When engaged on the 2c side, the transfer roller is guided to the transfer position X by its own weight, and the convenience of replacement work is further enhanced.

(3) Further, in the guiding process of the transfer roller 26, annular members 40, 40 are provided for maintaining the engagement state between the end portions 26c and the transfer roller guide grooves 65. 26 can be easily guided while maintaining the posture capable of being mounted at the transfer position X.
(4) In this embodiment, the transfer roller unit is not provided with a holder or the like, and the entire surface of the roller 26b of the transfer roller 26 is exposed to the outside. By applying the present invention, the surface of the roller 26b It is possible to perform the mounting operation while preventing the operator's hand from touching or coming into contact with other components inside the apparatus main body 1a.

<Embodiment 2>
6 and 7 show a second embodiment (corresponding to the inventions of claims 6 and 10). The difference from the above-described embodiment is that the process cartridge 12 is also guided by the transfer roller guide groove 65 and that a pushing portion 70 for pushing the transfer roller 26 into the process cartridge 12 is provided. The other points are the same as those of the first embodiment. Therefore, the same reference numerals as those in the first embodiment are given and the redundant description is omitted, and only different points will be described next.

1. In this embodiment, the total length of the roller shaft 21a of the photosensitive drum 21 of the process cartridge 12 is designed to be substantially the same as the total length of the roller shaft 26a of the transfer roller 26, as shown in FIGS. As described above, the end 21b of the photosensitive drum 21 protruding from the side surface of the process cartridge 12 (the “end of the process cartridge” of the present invention) is also engaged and guided in the transfer roller guide groove 65 described above. It has become.
Further, in the present embodiment, as shown in FIG. 6, a pair of push-in portions 70 protruding downward are provided at both ends of the front end portion of the process cartridge 12. As shown in FIG. 7, the pair of pressing portions 70 can come into contact with the portion of the end portion 26 c of the transfer roller 26 inserted previously between the roller 26 b and the opposing wall 60 from behind. It is arranged in the position.

2. Effects of the Present Embodiment According to the present embodiment, the transfer roller guide groove 65 engages not only with the transfer roller 26 but also with the end portion 21b of the process cartridge 12 so that the process cartridge 12 is positioned at the image forming position from the opening 2c side. It is configured to guide to Y. Therefore, the space for forming the guide engaging portion can be saved compared to the configuration in which the transfer engaging roller 26 and the process cartridge 12 are provided with separate guide engaging portions.
Further, for example, even when the previously inserted transfer roller 26 remains in the middle of the passage 2b from the opening 2c to the transfer position X, the pushing portion 70 of the process cartridge 12 to be inserted later, The transfer roller 26 is pushed by 70 and can be guided to the transfer position X. Accordingly, even if the transfer roller guide groove 65 is formed horizontally from the opening 2c side to the transfer position X, or is inclined upward toward the front in the insertion direction, the transfer roller 26 is moved. It is possible to reliably guide to the transfer position X.

<Embodiment 3>
FIG. 8 shows a third embodiment (corresponding to the invention of claim 7). The difference from the above embodiment is that a guide groove dedicated to the process cartridge 12 is provided separately from the transfer roller guide groove, and the other points are the same as in the first embodiment. Therefore, the same reference numerals as those in the first embodiment are given and the redundant description is omitted, and only different points will be described next.

1. Configuration of this Embodiment As shown in FIG. 8, a transfer roller guide groove 91 for guiding the transfer roller 26 and a process cartridge guide groove for guiding the process cartridge 12 thereon are formed on the opposing wall 60. 92 are formed. The transfer roller guide groove 91 has a larger inclination angle near the upper position of the transfer position X from the opening 2c, reaches the upper position, bends directly from the upper position toward the transfer position X, and It is formed to have the same width over the entire length.

On the other hand, the process cartridge guide groove 92 is configured to be engaged with the end portion 21 b of the photosensitive drum 21. Further, the process cartridge guide groove 92 is inclined downward from the opening 2c toward the upper position of the image forming position Y where the photosensitive drum 21 and the transfer roller 26 are opposed to each other, and from the upper position to the image forming position Y. Further, in the present embodiment, as shown in FIG. 8, the diameter d1 of the roller shaft 26a of the transfer roller 26 is set to be photosensitive. It is larger than the diameter d2 of the roller shaft 21a of the drum 21. The width d4 of the process cartridge guide groove 92 is designed to be larger than the diameter d2 of the roller shaft 21a of the photosensitive drum 21 and smaller than the diameter d1 of the roller shaft 26a of the transfer roller 26. On the other hand, the width d3 of the transfer roller guide groove 91 is designed to be wider than the diameter d1 of the roller shaft 26a of the transfer roller 26. That is, normally, the transfer roller 26 inserted first cannot be inserted into the process cartridge guide groove 92.

2. Effects of this Embodiment In this embodiment, dedicated guide grooves 91 and 92 are formed in the transfer roller 26 and the process cartridge 12, respectively. Normally, the transfer roller 26 that is inserted first cannot be inserted into the process cartridge guide groove 92, so that the transfer roller 26 may be erroneously inserted into the process cartridge guide groove 92. Can be prevented.

<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 transfer roller unit is a single transfer roller including only the transfer roller 26. However, the present invention is not limited to this, and the transfer roller and a holder for rotatably holding the transfer roller at both ends are provided. It may be a transfer roller unit. However, when the transfer roller is a single unit, the entire roller surface of the transfer roller is exposed to the outside, and there is a high possibility that the operator's hand touches the roller surface or contacts other parts inside the apparatus main body. Therefore, it is particularly useful to apply the above inventions to such a configuration. Further, since only the transfer roller alone needs to be replaced, the replacement cost can be reduced when the transfer roller unit having the holder is replaced.

  (2) As a drop-off prevention mechanism, for example, the one shown in FIG. That is, a guide groove 101 is further formed in the receiving surface 100 that receives the end portion 26c of the transfer roller 26 in the guide groove 65 for the transfer roller, and the peripheral portion of the large diameter portion 41 of the annular member 40 is inserted and guided therein. Even the configuration is included in the configuration of claim 4 of the present invention. Note that the guide groove is also formed on the upper surface (not shown) of the transfer roller guide groove 65 facing the receiving surface 100, and the upper and lower portions of the annular member 40 are engaged and guided by the upper surface and the upper surface. It may be.

  (3) Furthermore, another configuration shown in FIG. That is, the transfer roller unit is configured to include the transfer roller 26 and the holder 102 that rotatably holds the both end portions 26c thereof, and the protruding portions 103 (engagement) projecting in an L shape from each end surface of the holder 102. A structure may be adopted in which the leading end of the joint protrusion is inserted into the guide groove 101 of the receiving surface 100 and guided.

  (4) Even if what corresponds to the push-in portion 70 of the second embodiment is applied to the first and third embodiments, the same effect as that of the second embodiment can be obtained.

1 is a side sectional view of a main part of a laser printer according to Embodiment 1 of the present invention. Side cross-sectional view showing enlarged process cartridge Cross-sectional side view of the main part of the laser printer with the transfer roller and process cartridge removed Simplified view of the engagement state between the end of the transfer roller and the guide groove for the transfer roller as viewed from above the passage. Simplified view of the engagement state between the end of the transfer roller and the guide groove for the transfer roller as viewed from the opening side of the apparatus body Sectional side sectional view of the main part of the laser printer according to the second embodiment Simplified view of the engagement state between the transfer roller and process cartridge end and the transfer roller guide groove from above the passage Cross-sectional side view of main parts of a laser printer according to Embodiment 3 Simplified view from the opening side showing deformation of the drop-off prevention mechanism (1) Simplified view seen from the opening side showing deformation of the drop-off prevention mechanism (2)

Explanation of symbols

1. Laser printer (image forming device)
DESCRIPTION OF SYMBOLS 1a ... Apparatus main body 2b ... Passage path 2c ... Opening part 3 ... Paper (recording medium)
12 ... Process cartridge 21 ... Photosensitive drum (image carrier)
21b ... end (end of process cartridge)
26: transfer roller 26c: end (end of transfer roller)
40 ... annular member (regulator member)
57 ... conveying path 60 ... opposing wall 65, 91 ... guide groove for transfer roller (guide engaging portion for transfer roller unit)
70 ... Press-in portion 92 ... Process cartridge guide groove (guide engagement portion for process cartridge)
X: Transfer position Y: Image formation position

Claims (11)

A transfer roller unit for transferring a toner image formed on the image carrier to a recording medium;
The transfer roller unit that has an opening and is inserted into the recording medium from the opening includes an apparatus main body that is mounted at a transfer position where the toner image can be transferred to a recording medium.
Each of the opposing walls of the passage path through which the transfer roller unit passes from the opening side to the transfer position inside the apparatus main body is engaged with an end of the transfer roller unit, and the transfer roller unit is An image forming apparatus, characterized in that a guide engaging portion capable of guiding from the opening side to the transfer position is formed. The image forming apparatus according to claim 1, wherein the transfer roller unit is mounted at the transfer position while being guided in a state in which an axial direction of the transfer roller is orthogonal to an insertion direction from the opening. apparatus. The image forming apparatus according to claim 1, wherein the guide engaging portion is inclined downward from the opening side toward the transfer position. A drop prevention between the end portion of the transfer roller unit and the guide engagement portion for maintaining the engagement state between the end portion and each guide engagement portion in the guide process of the transfer roller unit. The image forming apparatus according to claim 1, further comprising a mechanism. The guide engaging portion is constituted by a guide groove or a guide step portion that engages with a tip portion of an end portion of the transfer roller unit,
The drop-off prevention mechanism abuts against the guide groove or the peripheral wall of the guide step portion of the facing wall, and the longitudinal direction of the transfer roller unit and the guide direction of the transfer roller unit by the guide engaging portion are formed. The image forming apparatus according to claim 4, wherein a regulating member that regulates an angle within a predetermined range is provided at each end of the transfer roller unit. The apparatus main body has an image formation in which a process cartridge having the image carrier is inserted into the opening through the opening, and the transfer roller of the transfer roller unit mounted at the transfer position can contact the image carrier. It is configured to be attached to the position,
The guide engaging portion is configured to engage not only the end portion of the transfer roller unit but also the end portion of the process cartridge, and guide the process cartridge from the opening side to the image forming position. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The apparatus main body has an image formation in which a process cartridge having the image carrier is inserted into the opening through the opening, and the transfer roller of the transfer roller unit mounted at the transfer position can contact the image carrier. It is configured to be attached to the position,
In addition to the guide engaging portion for the transfer roller unit, each of the opposing walls of the passageway engages with an end portion of the process cartridge, and the process cartridge is moved from the opening side to the image forming position. And a guide engaging portion for a process cartridge capable of being guided is formed,
The guide engaging portion for the transfer roller unit cannot be engaged with the end of the process cartridge, and / or the guide engaging portion for the process cartridge cannot be engaged with the end of the transfer roller unit. 6. The image forming apparatus according to claim 1, wherein the image forming apparatus has a configuration. 8. The image forming apparatus according to claim 7, wherein the guide engaging portion for the process cartridge is inclined downward from the opening side toward the image forming position. 9. The process cartridge is mounted at the image forming position by being guided in a state in which an axial direction of an image carrier is orthogonal to an insertion direction from the opening. The image forming apparatus according to any one of the above. 7. The process cartridge according to claim 6, wherein a part of the process cartridge can contact the transfer roller unit from the rear in the insertion direction of the transfer roller unit in the process of guiding the process cartridge. Item 12. The image forming apparatus according to Item 9. 11. The image forming apparatus according to claim 1, wherein the transfer roller unit is a single transfer roller, and the end portion is an end portion of a roller shaft body of the single transfer roller.

Images