JP4385820B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

2. Description of the Related Art Conventionally, there has been provided an image forming apparatus such as a laser printer in which a transfer roller is detachably attached to an apparatus main body. The transfer roller is usually mounted in the main body of the image forming apparatus while being rotatably held by a bearing. However, the transfer roller needs to be detachable in order to cope with maintenance and replacement.
JP 2002-89547 A

  By the way, as a structure of the bearing portion that rotatably holds the transfer roller, a configuration that can hold the shaft member in a wider range in the circumferential direction is desirable, and if the shaft member is configured not to be detached in the direction orthogonal to the axial direction, The bearing configuration can stably hold the shaft member. However, when such a configuration is used, when the transfer roller is removed from the bearing portion, the transfer roller cannot be removed by being relatively displaced in the direction perpendicular to the axial direction with respect to the bearing portion. In order to perform well, a special structure must be provided, and the configuration may be complicated.

  In Patent Document 1, the transfer roller is rotatably held by a bearing portion, and the transfer roller is mounted on the apparatus main body portion by engaging the bearing portion and a hook portion that can be flexibly deformed. In this configuration, the transfer roller and the bearing portion can be integrally detached from the apparatus main body portion by releasing the engaged state between the bearing portion and the hook portion. However, in the configuration in which the transfer roller and the bearing unit are integrally detached from the apparatus main body unit, even when it is desired to perform maintenance or replacement of only the transfer roller, the bearing unit must be removed integrally. The object becomes larger and more complicated. In addition, if a mechanism that allows the bearing portion to be attached / detached is provided, the attachment / detachment mechanism may become large and complicated, or may become difficult to operate.

  The present invention has been made based on the above circumstances, and an object thereof is to provide a configuration in which a transfer roller is stably held by a bearing portion and the transfer roller can be easily attached and detached. To do.

As means for achieving the above object, the invention of claim 1 is directed to an image carrier that carries a visible image formed by developing an electrostatic latent image with a developer, and the image carrier. A transfer roller having a roller portion disposed opposite to the shaft member that holds the roller portion, and a pair of bearing portions that support both end portions of the shaft member, and the transfer roller includes: In the image forming apparatus mounted on the apparatus main body, at least one of the pair of bearings includes a movable bearing configured to be movable, and the movable bearing may include the entire circumferential direction of the shaft member or an engagement shape capable portion surrounding a portion, and a support position in which the shaped portion is in irremovably said shaft member engaged with the shaft member in a direction intersecting the axial direction of the transfer roller, the The shape part comes off the shaft member and Characterized in that it is moved capable of changing the member to the disengaged position to allow detachment to the crossing direction.

  The “image carrier” referred to in the claims only needs to have a structure for carrying a visible image, and includes not only a photosensitive drum (photosensitive member) but also an intermediate transfer member. In addition, the “apparatus main body” is a part configured by removing at least the transfer roller from the entire image forming apparatus. The “image forming apparatus” is not limited to a configuration capable of forming an image, and 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. Further, as described above, the “apparatus main body” is a part configured by removing at least the transfer roller from the entire image forming apparatus. However, in the configuration in which a process cartridge is used as in the sixteenth aspect, It is a portion formed by removing both the transfer roller and the process cartridge from the entire forming apparatus.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the moving bearing portion includes a hole portion that supports the shaft member in the entire circumferential direction.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the position opposite to the image carrier side with respect to the shaft member is lower than the moving bearing portion. A support portion that receives the shaft member that has not come into contact with the shaft member when the moving bearing portion is in the support position and has come down from the moving bearing portion when the moving bearing portion moves to the disengagement position. Is provided.

  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 opening end portion of the movable bearing portion on the side where the shaft member is inserted, and the shaft member. A chamfered portion is formed in at least one of the end portions on the side to be inserted into the moving bearing portion.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the moving bearing portion is configured to be slidable in the axial direction.

  According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect of the present invention, the holding base that holds the moving bearing portion, the supporting base that is supported by the holding base, and the moving bearing portion that is biased toward the image bearing side. And a bearing unit comprising the moving bearing portion, the urging member, and the holding base is configured to be slidable in the axial direction.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, when the urging direction by the urging means is a height direction, the shaft member is inserted into and removed from the movable bearing portion. A height setting section is provided for setting the height of the moving bearing section so that the height of the moving bearing section differs between the support position and the disengagement position.

  According to an eighth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, when the moving bearing portion is in the support position, the moving bearing portion is pushed out toward the image carrier. The shaft that has been released from the moving bearing portion and is released from the moving bearing portion when the moving bearing portion is displaced from the support position to the disengagement position. The member is supported by the pressing means.

  According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect, when the pressing direction by the pressing unit is a height direction, the shaft member is inserted into and removed from the movable bearing portion. The moving bearing portion slides in the axial direction in a state where the height is constant between the support position and the separation position.

  A tenth aspect of the present invention is the image forming apparatus according to any one of the first to ninth aspects, wherein the sheet is sandwiched between the transfer roller and the image carrier, and the sheet is rotated by the rotation of the image carrier. The transfer roller rotates in conjunction with the movement of the sheet by a frictional force generated between the transfer roller and the sheet.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, the shaft member of the transfer roller is a gear for transmitting power from the outside to the transfer roller. A member is provided, and the gear member is provided between the pair of bearing portions in the axial direction.

  According to a twelfth aspect of the present invention, in the image forming apparatus according to the eleventh aspect, the gear member is disposed only on one end side of the shaft member, and the gear member is provided among the pair of bearing portions. Only the side bearing portion is configured as the moving bearing portion.

  According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the first to twelfth aspects, only one of the pair of bearing portions serves as the moving bearing portion, and the other of the pair of bearing portions. An electrode portion for applying a voltage to the shaft member is connected on the bearing portion side.

  According to a fourteenth aspect of the present invention, in the image forming apparatus according to any one of the first to thirteenth aspects, only one of the pair of bearing portions is the moving bearing portion, and the other bearing portion. Is configured to be displaceable so that the insertion direction of the shaft member is changed.

  According to a fifteenth aspect of the present invention, in the image forming apparatus according to any one of the first to fourteenth aspects, the image forming apparatus directs a sheet supplied from one end side in the longitudinal direction of the sheet feeding cassette toward the other end side. The first direction changing portion that changes the direction and sends it to the transfer roller side disposed above the sheet feeding cassette, and changes the direction of the sheet that has passed through the transfer roller toward the one end side, and And a second direction changing section that feeds the sheet discharge section disposed above the transfer roller.

  According to a sixteenth aspect of the present invention, there is provided the image forming apparatus according to any one of the first to fifteenth aspects, wherein the process cartridge includes at least the image carrier and is configured to be detachable from the apparatus main body. The apparatus main body is formed with an accommodating portion for accommodating the process cartridge, and an opening communicating with the accommodating portion is formed on one end side of the apparatus main body, via the opening The process cartridge is attachable and detachable, and the transfer roller is configured to be exposed to the accommodating portion side in a state where the process cartridge is detached from the apparatus main body portion, and to the accommodating portion side in the exposed state. The apparatus is detached from the apparatus main body by detaching.

  According to a seventeenth aspect of the present invention, in the image forming apparatus according to the sixteenth aspect, the transfer roller is detached from the main assembly of the apparatus in a direction substantially perpendicular to the axial direction to be separated from the storage section. Features.

  According to an eighteenth aspect of the present invention, in the image forming apparatus according to the sixteenth aspect, a direction in which the process cartridge is removed from the housing portion is a direction substantially perpendicular to the axial direction.

<Invention of Claim 1>
If it does in this way, it will become the structure by which a transfer roller is stably hold | maintained at a bearing part, and it becomes a structure which can attach or detach a transfer roller easily.

<Invention of Claim 2>
According to this configuration, since the shaft member can be supported over the entire circumferential direction by the hole portion, a bearing configuration capable of rotating the transfer roller more stably is obtained.

<Invention of Claim 3>
According to this configuration, when the moving bearing portion moves from the support position to the disengagement position, the transfer roller can be prevented from falling by the support portion, so that the user can easily access when replacing the transfer roller. It becomes.

<Invention of Claim 4>
If it does in this way, since a shaft member will be guided in a movement bearing part by a chamfering part, it will become the composition which can perform operation which inserts a shaft member in a movement bearing part smoothly.

<Invention of Claim 5>
In this way, the transfer roller can be configured so as not to be detached from the bearing portion in a direction intersecting the axial direction, while the transfer roller can be easily attached to and detached from the bearing portion.

<Invention of Claim 6>
If it does in this way, it becomes a suitable composition which can slide a movement bearing part and can urge a movement bearing part to the image carrier side in a support position.

<Invention of Claim 7>
If it does in this way, when inserting and detaching a shaft member to and from a moving bearing part, it can be set as appropriate height in a support state and a separation state, respectively.

<Invention of Claim 8>
In this way, it is possible to attach / detach the shaft member to / from the moving bearing portion by sliding the moving bearing portion without sliding the pressing means while taking the configuration in which the moving bearing portion is pushed to the image carrier side. There is no need to provide a special mechanism for sliding, and the number of parts can be reduced.

<Invention of Claim 9>
In this way, since the moving bearing part moves at a constant height, the movement is smooth, and the height is constant between the support position and the separating position. Thereafter, when the shaft member is again inserted into the bearing portion, the insertion is easily performed.

<Invention of Claim 10>
According to this configuration, it is possible to simplify the configuration by omitting a power transmission member such as a gear member.

<Invention of Claim 11>
If it does in this way, it will become the composition which can slide a moving bearing part without trouble, providing a gear member.

<Invention of Claim 12>
If the moving bearing portion is arranged only on one side in this way, the attachment / detachment mechanism can be simplified, and the gear member is interposed between the moving bearing portion and the roller portion. Therefore, it is possible to prevent the roller portion from being shocked or damaged.

<Invention of Claim 13>
By doing so, the bias voltage can be stably applied.

<Invention of Claim 14>
If it does in this way, it can change an insertion direction so that it may become a suitable direction which is easy to insert a shaft member in the other side, and it will become the composition which makes it easier to insert a shaft member when attaching a transfer roller.

<Invention of Claim 15>
According to this configuration, the apparatus can be reduced in size, and on the other hand, the transfer roller can be easily detached by operating the slide member. Therefore, it becomes difficult to remove the transfer roller due to the downsizing of the apparatus. This is an effective configuration.

<Invention of Claim 16>
If it does in this way, it becomes the composition which can attach and detach a transfer roller using a storage part which stores a process cartridge.

<Invention of Claim 17>
Thus, if it is set as the structure which makes it detach | leave by displacing in the direction orthogonal to an axial direction, it will become a structure which can detach | leave easily without accompanying a large operation.

<Invention of Claim 18>
By doing so, the process cartridge can be easily mounted on the apparatus main body.

<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 as a recording medium in a main body casing 2, an image forming unit 5 for forming a predetermined image on the fed sheet, and the like. It has.

(1) Configuration of Feeder Unit The feeder unit 4 includes a paper feed cassette 43 that is detachably attached to the bottom of the main body casing 2, a paper pressing plate 6 provided in the paper feed cassette 43, and a paper feed cassette. The paper feed roller 7 and the paper feed pad 8 provided above one end of the paper 43, the transport roller 59 provided on the downstream side in the paper transport direction with respect to the paper feed roller 7, and the paper with respect to the transport roller 59 And a registration roller 9 provided on the downstream side in the conveying direction.

  The sheet pressing plate 6 can stack sheets in a stacked manner, and an end far from the sheet feeding roller 7 is supported so as to be swingable, and a near end is rotatable in the vertical direction. Moreover, it is urged | biased upwards by the spring which is not shown in figure 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 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 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 pad are rotated by the rotation of the sheet feeding roller 7. After being sandwiched between 8, the paper is fed one by one. The fed sheet is guided by the guide unit 61 so as to be folded back to the side opposite to the fed sheet side, and further fed to the registration roller 9 by the conveying roller 59. 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 unit 12 side to be described later. These rollers are sandwiched between the driving roller 44 and the driven roller 45 and are sent to the image forming unit 5 after a predetermined registration. In this embodiment, the guide part 61 and the conveyance roller 59 correspond to a first direction changing part. As a result, the direction of the sheet fed from one end side (front side) in the longitudinal direction of the sheet feed cassette 43 is changed toward the other end side (rear side) and sent to the transfer roller 26 side.

  The feeder unit 4 further includes a manual feed tray 57 and a paper feed roller 58 for feeding sheets stacked on the manual feed tray 57. The feeder unit 4 is stacked on the manual feed tray 57. The paper to be fed can be sent to the transport roller 59 by the paper feed roller 58.

(2) Configuration of Image Forming Unit The image forming unit 5 includes a scanner unit 11, a process unit 12 as a process cartridge referred to in the claims, a fixing unit 13, and the like.

(A) Configuration of Scanner Unit The scanner unit 11 is provided in the upper part in the main body casing 2, and includes a laser light emitting unit (not shown), a polygon mirror 14 that is driven to rotate, lenses 15 and 16, and reflecting mirrors 17 and 18. , 19, and the like, and a polygon beam 14, a lens 15, reflecting mirrors 17 and 18, a lens 16, and a reflecting mirror 19, as indicated by a chain line, a laser beam based on predetermined image data emitted from the laser emitting section. Are passed or reflected in this order to irradiate the surface of the photosensitive drum 21 of the process unit 12 described later by high-speed scanning. In the present embodiment, the photosensitive drum 21 corresponds to an image carrier in the claims.

(B) Configuration of Process Unit Next, the process unit 12 will be described with reference to FIG.
FIG. 2 is an enlarged side sectional view showing the process unit 12. In the figure, a process unit 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 40 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 is achieved.

(C) Configuration of Transfer Roller As shown in FIG. 4, the transfer roller 26 according to the present embodiment is configured to be mounted on the apparatus main body 1a and faces the photosensitive drum 21 corresponding to an image carrier. The roller part 26a arrange | positioned by this and the shaft member 26b which hold | maintains this roller part 26a are comprised. On the other hand, on the apparatus main body 1a side, in order to hold the transfer roller 26, a pair of bearing portions 80, 80 for supporting both end portions 90, 90 of the shaft member 26b are provided. One of the pair of bearing portions 80, 80 is configured as a movable bearing portion 83 configured to be movable. The moving bearing 83 is moved and changed between a support position for supporting the shaft member 26b so that it cannot be detached in a direction crossing the axial direction (Z-axis direction) of the transfer roller 26, and a separation position for removing the shaft member 26b. It is configured to be possible.

  The moving bearing portion 83 is configured to be slidable in the axial direction of the shaft member 26b. From the state where the shaft member 26b is held by the moving bearing portion 83, until the holding state is completely released as shown in FIG. That is, it slides (until the shaft member 26b is completely removed from the hole 83a). In the present embodiment, as shown in FIG. 5, a holding base 85 that holds the moving bearing portion 83, and a spring member that is supported by the holding base 85 and biases the moving bearing portion 83 toward the photosensitive drum 21. 87 (the spring member 87 corresponds to the biasing member). A bearing unit 81 including a moving bearing portion 83, a spring member 87, and a holding base 85 is configured to be slidable in the axial direction of the shaft member 26b. As shown in FIGS. 10A and 10B, the bearing unit 81 is engaged with a protrusion 85 d provided on the holding base 85 and one end of a spring member 87 formed of a compression coil spring, so that the moving bearing portion 83 is engaged. The provided protrusion 83d and the other end of the spring member 87 are engaged with each other. With this configuration, the moving bearing 83 is urged away from the holding base 85. FIG. 10A is an exploded view of the bearing unit 81 viewed from the side, and FIG. 10B is a view of the moving bearing portion 83 and the holding base 85 viewed from the front.

  As shown in FIGS. 5 and 6, the moving bearing portion 83 includes a hole portion 83 a that supports the shaft member 26 b over the entire circumferential direction, and the side on which the shaft member 26 b is inserted in the moving bearing portion 83. A chamfered portion 83c is formed at the opening end of the. The chamfered portion 83c may be formed in a flat shape or may be formed in a round shape (in the example of FIGS. 5 and 6, it is formed in a flat shape). Further, a chamfered portion may be formed at an end portion (that is, a tip portion) of the shaft member 26b on the side to be inserted into the moving bearing portion 83, instead of the opening end portion on the side where the shaft member 26b is inserted in the moving bearing portion 83. In addition, the chamfered portion may be formed at both the opening end portion of the moving bearing portion 83 on the side where the shaft member 26b is inserted and the end portion of the shaft member 26b on the side where the shaft member 26b is inserted.

  The shaft member 26b of the transfer roller 26 is provided with a gear member 92 for transmitting power from the outside to the transfer roller 26. A pair of bearing portions 80, 80 are provided in the axial direction of the shaft member 26b. A gear member 92 is provided between (the fixed bearing portion 82 and the moving bearing portion 83). The gear member 92 is disposed only on one end side of the shaft member 26 b, and only the bearing portion 80 on the side where the gear member 92 is provided is configured as the moving bearing portion 83 of the pair of bearing portions 80, 80. .

  In the present embodiment, as described above, only one of the pair of bearings 80, 80 is the moving bearing 83, but as shown in FIG. 5, the other bearing (fixed bearing) is used. On the side of the part 82), an electrode part 94 for applying a voltage to the shaft member 26b is connected. In this configuration, since the bearing portion 80 on the side where the electrode portion 94 is provided is configured as the fixed bearing portion 82 and does not move, the electrode portion 94 does not need to have a special structure corresponding to the movement, and the configuration is simplified. And a bias voltage can be stably applied.

  Further, as shown in FIG. 6, the shaft member 26b is supported at a position opposite to the photosensitive drum 21 side with respect to the shaft member 26b when the movable bearing portion 83 moves from the support position to the separation position. A supporting portion 95 is provided. In the state where the shaft member 26b is supported by the moving bearing portion 83, the support portion 95 is slightly below the shaft member 26b with a slight gap in this state so that the upper surface 95a does not contact the shaft member 26b. 6 and supports the transfer roller 26 that tends to drop downward in a state in which the shaft member 26b is removed from the moving bearing 83 as shown in FIG. According to this configuration, since the transfer roller 26 can be supported in a slightly submerged state, the transfer roller 26 does not drop significantly, and the transfer roller 26 can be effectively protected. Further, if the transfer roller and the support portion are always in contact with each other, an extra resistance is generated, but the support portion does not adversely affect the rotation of the transfer roller because there is a slight gap. Further, since the transfer roller 26 separated from the moving bearing portion 83 does not sink to the lower side, the transfer roller 26 can be easily accessed.

  In the present embodiment, the bearing unit 81 is configured to be slidable as described above. More specifically, as shown in FIGS. 7 to 9, as the bearing unit 81 slides, the moving bearing unit The height of 83 is changed. FIG. 7A is a conceptual perspective view for conceptually explaining the relationship between the bearing unit 81 and the height setting guide portion 97 (described later), and FIG. 7B is a diagram showing the height setting guide portion 97 as a two-dot chain line. It shows the inside. FIG. 8 is a front conceptual diagram illustrating the relationship, and FIG. 9 is a side conceptual diagram illustrating the relationship. In FIG. 8, the gear member 92 is not shown.

  As shown in FIGS. 7 to 9, when the biasing direction (Y-axis direction in FIG. 7) by the spring member 87 is the height direction, the shaft member 26b is inserted into and removed from the moving bearing portion 83. A height setting guide portion 97 for setting the height of the moving bearing portion 83 so that the height of the moving bearing portion 83 can be changed between the support position and the disengagement position. (Corresponding to a height setting section in the range). As shown in FIGS. 7A and 7B and FIG. 9, a pair of flange-like protruding portions 83b and 83b are formed in a part of the moving bearing portion 83, and above the protruding portions 83b and 83b. The pair of height setting guide portions 97 are opposed to each other in a form projecting in the front-rear direction and are configured along the axial direction (Z direction).

  As shown in FIG. 8, the moving bearing 83 is constantly in contact with the lower end 97a of the height setting guide 97 by the urging of the spring member 87, and in the axial direction (arrow direction) according to the operator's operation. Although it slides, since the height of the lower end part 97a of the height setting guide part 97 is changed according to the position of the axial direction, the height of the moving bearing part 83 is changed according to the height of the lower end part 97a. Changes. That is, in the support position or in the vicinity of the support position, the height of the hole 83a (see FIG. 5) in the moving bearing portion 83 becomes a height corresponding to the shaft member 26b, and gradually decreases as the distance from the support position increases. It is configured as follows. In FIG. 8, the alternate long and two short dashes line conceptually shows the position and configuration of the height setting guide portion 97 in correspondence with the moving bearing portion 83 and the like, and reference numerals 81 ′ and 83 ′ denote bearing units and moving bearings. The part has shown the state which left | separated to some extent from the support position.

In the present embodiment, the movement bearing portion 83 can be moved and changed between the support position and the disengagement position, but various configurations can be used for holding the movement bearing portion 83 at the support position. FIG. 11 shows an example thereof, (a) is a conceptual plan view, and (b) is a perspective conceptual diagram. In FIG. 11, a slide restricting member 99 is provided as a restraining means for restraining the displacement of the moving bearing 83 at the support position. The slide restricting member 99 is configured to be rotatable in a direction parallel to the axial direction, and is displaced between a restrained position as shown by a solid line in FIG. 11B and an unconstrained position as shown by a broken line. It is supposed to be. As shown in FIGS. 11A and 11B, the slide restricting member 99 is in contact with the end of the shaft member 26b and the moving bearing portion 83 in the restrained position, and the displacement of the moving bearing portion 83 is displaced in the axial direction. regulate. In order to keep the slide restricting member 99 from rotating at the restraining position, a rotation restricting member (for example, an engaging means (such as an engaging claw) for engaging the slide restricting member 99 and the bottom 72) is provided. Also good. Further, the method shown in FIG. 11 is merely an example for holding the position of the moving bearing portion 83, and other methods may be used as long as the moving bearing portion 83 can be held in position.

  In the present embodiment, as shown in FIG. 3, the apparatus main body 1a of the laser printer 1 is formed with an accommodating section 70 for accommodating the process unit 12, and at one end of the apparatus main body 1a. An opening 74 communicating with 70 is formed, and the process unit 12 is detachable through the opening 74. And the direction which removes the process unit 12 from the accommodating part 70 is made into the direction substantially orthogonal to the axial direction of the shaft member 26b. On the other hand, as shown in FIG. 3, the transfer roller 26 is configured to be exposed to the accommodating portion 70 side when the process unit 26 is detached from the apparatus main body 1a, and is separated to the accommodating portion 70 side in the exposed state. It is removed from the apparatus main body 1a. Specifically, it is detached from the bottom portion 72 of the apparatus main body 1a in the direction substantially orthogonal to the axial direction of the shaft member 26b, thereby separating to the accommodating portion 70 side.

(D) Configuration of Fixing Unit As shown in FIG. 1, the fixing unit 13 is disposed on the downstream side of the process unit 12, and includes a heating roller 32, a pressing roller 31 pressed against the heating roller 32, and these heating units. A pair of conveying rollers 33 provided on the downstream side of the roller 32 and the pressing roller 31 is provided. The heating roller 32 is made of metal and includes a halogen lamp for heating. The toner transferred on the paper in the process unit 12 is heated while the paper passes between the heating roller 32 and the pressing roller 31. After fixing, the paper is conveyed to the paper discharge path 56 by the conveyance roller 33. The sheet sent to the paper discharge path 56 is sent to a paper discharge roller 34 described later, and is discharged onto the paper discharge tray 35 by the paper discharge roller 34. In the present embodiment, the transport roller 33, the paper discharge path 56, and the paper discharge roller 34 correspond to a second direction changing portion referred to in the claims, and the sheet that has passed through the transfer roller 26 by these is the front side. The direction is changed so as to be directed to the paper discharge tray 35 (the paper discharge tray 35 corresponds to a paper discharge portion in the claims) side.

  In the laser printer 1, the toner remaining on the photosensitive drum 21 after being transferred onto the sheet by the transfer roller 26 is collected by the developing roller 22, and the remaining toner is collected 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 of Double-sided Image Forming Unit The laser printer 1 is provided with a reversal conveyance unit 52 as a double-sided image forming unit in order to form images on both sides of the paper. The reverse conveyance unit 52 includes a paper discharge roller 34, a reverse conveyance path 53, a flapper 54, and a reverse conveyance roller 55.

  The paper discharge roller 34 includes a pair of rollers and is configured to be able to switch between forward rotation and reverse rotation. As described above, the paper discharge roller 34 rotates in the forward direction when the paper is discharged onto the paper discharge tray 35, but rotates in the reverse direction when the paper is reversed. The reverse conveyance path 53 is provided along the vertical direction so that the paper can be conveyed from the paper discharge roller 34 to the reverse conveyance roller 55 disposed below the image forming unit 5. The end portion is disposed near the paper discharge roller 34, and the downstream end portion thereof is disposed near the reverse conveyance roller 55.

  The flapper 54 is swingably provided so as to face a branch portion between the paper discharge path 56 and the reverse conveyance path 53, and the paper is reversed by the paper discharge roller 34 by excitation or non-excitation of a solenoid (not shown). Is configured to be able to be switched from the direction toward the paper discharge path 56 to the direction toward the reverse conveyance path 53. The reverse conveyance roller 55 is located above the sheet feeding cassette 43, and its upstream end is disposed near the rear end of the reverse conveyance path 53, and its downstream end is the end of the registration roller 9. It is provided in a substantially horizontal direction so as to be disposed below.

  When forming images on both sides of the paper, the reversing conveyance unit 52 is operated as follows. That is, when a sheet with an image formed on one side is sent from the sheet discharge path 56 to the sheet discharge roller 34 by the transport roller 33, the sheet discharge roller 34 rotates forward with the sheet sandwiched therebetween. When the paper is once transported outward (discharge tray 35 side), most of the paper is sent to the outside, and the rear end of the paper is sandwiched between paper discharge rollers 34, the forward rotation is stopped. Next, the paper discharge roller 34 rotates in the reverse direction, and the flapper 54 switches the conveyance direction so that the paper is conveyed to the reverse conveyance path 53, and conveys the paper to the reverse conveyance path 53 in the reverse direction. To do. The flapper 54 is switched to the original state, that is, the state in which the paper fed from the transport roller 33 is sent to the paper discharge roller 34 when the transport of the paper is completed. Next, the sheet conveyed in the reverse direction to the reverse conveyance path 53 is conveyed to the reverse conveyance roller 55, reversed from the reverse conveyance roller 55 in the upward direction, and sent to the registration roller 9. The sheet conveyed to the registration roller 9 is turned upside down and again sent to the image forming unit 5 after a predetermined registration, whereby a predetermined image is formed on both sides of the sheet.

<Embodiment 2>
Next, Embodiment 2 will be described with reference to FIGS.
FIG. 12 conceptually illustrates the relationship between the transfer roller 26 and the moving bearing portion 183 in the second embodiment, and FIG. 13 illustrates the transfer roller 26, the pressing member 110, the moving bearing portion 183, and the guide groove 120. The positional relationship viewed from the front will be described for the support position (a) and the separation position (b). In this embodiment, when the moving bearing portion 183 is in the support position, a configuration is provided that includes pressing means 110 that presses the moving bearing portion 183 so as to push it toward the photosensitive drum 21 side. As shown in FIG. 12, when the moving bearing portion 183 is displaced from the support position to the disengaged position, the pressing of the moving bearing portion 183 by the pressing means 110 is released, and the shaft member 26 b detached from the moving bearing portion 183 is pressed by the pressing means 110. It has come to be supported by. The pressing means 110 is supported by a spring member 130 having one end fixed to the bottom portion 72. When the moving bearing portion 183 is at the support position as shown in FIG. It is configured to urge toward the photosensitive drum 21 side).

  When the pressing direction by the pressing means 110 (the Y-axis direction in the present embodiment) is the height direction, as shown in FIG. 13, when the shaft member 26b is inserted into and removed from the moving bearing portion 183, the moving bearing portion 183 slides in the axial direction with a constant height between the support position and the separation position. The guide groove 120 indicated by a two-dot chain line is a groove that is formed so as to extend in the axial direction, and is provided in a pair of front and rear to guide the overhanging portion 183b of the moving bearing portion 183. When the moving bearing portion 183 is moved from the support position as shown in FIG. 13A, the guide groove 120 guides the moving bearing portion 183 to have a substantially constant height.

<Embodiment 3>
Next, Embodiment 3 will be described with reference to FIG. FIG. 14 shows a configuration obtained by modifying FIG. 4, and illustrates the configuration of the bottom 72 of the accommodating portion according to the third embodiment. In FIG. 14, the point that the shaft member 26 b is not provided with a gear member is different from the other embodiments, and other points are the same. Description is omitted (particularly, the bearing unit 81 and the configuration in the vicinity thereof are the same as those in the first embodiment). In the present embodiment, the sheet is sandwiched between the transfer roller 26 and the photosensitive drum 21 and the sheet is moved by the rotation of the photosensitive drum 21. Further, the transfer roller 26 has friction generated between the sheet and the sheet. By force, it rotates in conjunction with the movement of the paper. That is, it is configured to be rotated by the action of the sheet conveyed by the rotation of the photosensitive drum 21.

<Embodiment 4>
Next, Embodiment 4 will be described with reference to FIGS. 15 and 16. FIG. 15 conceptually illustrates the transfer roller 26 and the pair of bearing portions 80 and 80 in the present embodiment. FIG. 16 is an explanatory diagram for explaining how to remove the transfer roller 26. In the present embodiment, only one of the pair of bearing portions 80, 80 is the moving bearing portion 83, and is configured to be displaceable between a support position for supporting the shaft member 26b and a disengagement position. The other bearing portion 182 is formed with a hole portion 182a capable of supporting the end portion 90 of the shaft member 26b (specifically, the end portion 90b opposite to the moving bearing portion 83) over the entire circumference. In the state where the shaft member 26b is supported by the bearing portion 182, the shaft member 26b is configured not to be detached from the bearing portion 182 in a direction intersecting the axial direction.

On the other hand, the bearing portion 182 (specifically, the entire bearing unit 180) is configured to be rotatable around the fulcrum portion 185a, and the bearing portion 182 is rotated by moving one of the bearing portions 83 to the disengagement position. As a result, the posture of the transfer roller 26 can be easily removed from the bearing portion 182 as shown in FIG. The other bearing portion 182 only needs to be rotatable, and the fulcrum portion 185a may or may not be connected to the bottom portion 72 (connected rotatably). In the present embodiment, the same bearing unit 81 as that of the first embodiment is provided on the moving bearing portion 83 side so as to be slidable in the axial direction, and a detailed description thereof will be omitted.

<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 the embodiment described above, the hole 83a is formed in the moving bearing 83, and the shaft member 26b is held by the hole 83a so as to surround the entire circumferential direction. However, the axial direction of the shaft member 26b is exemplified. If it is impossible to detach in the direction intersecting with the shaft member 26b, the shaft member 26b may be configured not to surround a part in the circumferential direction (for example, a configuration in which some slits are formed).
(2) In the above embodiment, the configuration in which the moving bearing portion is slid to the disengagement position is exemplified, but it may be disengaged without sliding. For example, as shown to Fig.17 (a), the structure which moves the moving bearing part 83 to the direction which cross | intersects the axial direction of the shaft member 26b, and may detach | leave may be sufficient. For example, in FIG. 17 (b), when the movement of the protruding portion 83b is restricted by the height restricting portion 72b at the support position while the moving bearing portion 83 slides away from the roller portion 26a, the opening is opened. The moving bearing 83 can be moved upward via the portion 72a. The shaft member 26b is not completely removed from the moving bearing portion 283 when it reaches the position of the opening 72a as shown in FIG. 17B, but the moving bearing portion 83 is also shown by the arrow in FIG. By moving (specifically, the entire bearing unit 81) upward, it can be completely removed. Such a configuration may be provided at both ends of the transfer roller 26, or one of them may be configured as described above, and the other end may be configured such that the bearing portion 80 can be rotated as in the fourth embodiment. Can be mentioned.

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 section of the main part of the laser printer with the process cartridge removed FIG. 1 is an enlarged view of a main part of the laser printer shown in FIG. Explanatory drawing explaining the relationship between a transfer roller and a bearing part The enlarged view which expands and shows the principal part of FIG. The perspective view explaining notionally the relationship between a bearing unit and a height setting guide part Front view conceptually explaining the relationship between the bearing unit and the height setting guide Side view conceptually explaining the relationship between the bearing unit and the height setting guide Exploded view showing exploded bearing unit 81 The figure which illustrates the holding method of a bearing unit Explanatory drawing explaining the principal part of the image forming apparatus of Embodiment 2. Explanatory drawing explaining attachment and detachment of the moving bearing part which concerns on Embodiment 2. FIG. The enlarged view which expands and shows the principal part of Embodiment 3. Explanatory drawing which illustrates notionally the principal part of the image forming apparatus of Embodiment 4. FIG. Explanatory drawing explaining the attachment or detachment mechanism of the transfer roller which concerns on Embodiment 4. FIG. The figure which illustrates the composition made to detach without depending on a slide

1. Laser printer (image forming device)
1a ... Device body 12 ... Process unit (process cartridge)
21. Photosensitive drum (image carrier)
26 ... Transfer roller 26a ... Roller part 26b ... Shaft member 35 ... Discharge tray (paper discharge part)
43 ... Paper feeding cassette 70 ... Accommodating section 74 ... Opening 97 ... Height setting guide (height setting section)

Claims (18)

An image carrier that carries a visible image formed by developing the electrostatic latent image with a developer;
A transfer roller comprising a roller portion disposed opposite to the image carrier, and a shaft member that holds the roller portion;
A pair of bearings that support both ends of the shaft member;
Have
The transfer roller is an image forming apparatus mounted on the apparatus main body,
At least one of the pair of bearing portions is composed of a movable bearing portion configured to be movable,
The moving bearing portion has a shape portion that can be engaged by surrounding the whole or a part of the shaft member in the circumferential direction, and the shape portion engages with the shaft member to place the shaft member in the axial direction of the transfer roller. The position is configured to be movable and changeable to a support position that makes it impossible to detach in the direction intersecting with and a detachment position that allows the shape part to come out of the shaft member and make the shaft member detachable in the intersecting direction. An image forming apparatus. The image forming apparatus according to claim 1, wherein the moving bearing portion includes a hole portion that supports the shaft member in the entire circumferential direction. The position opposite to the image carrier side with respect to the shaft member is lower than the moving bearing portion , and does not contact the shaft member when the moving bearing portion is in the support position, and the movement imaging, wherein the supporting portion for receiving said shaft member falls missing from the mobile bearing portion is provided in claim 1 or claim 2, wherein when the bearing unit is moved to the disengaged position apparatus. A chamfered portion is formed on at least one of an opening end portion on the side where the shaft member is inserted in the moving bearing portion and an end portion on the side where the shaft member is inserted into the moving bearing portion. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The image forming apparatus according to claim 1, wherein the moving bearing portion is configured to be slidable in the axial direction. A holding base for holding the moving bearing portion;
An urging member that is supported by the holding base and urges the moving bearing portion toward the image bearing side;
With
The image forming apparatus according to claim 5, wherein a bearing unit including the moving bearing portion, the urging member, and the holding base is configured to be slidable in the axial direction. When the urging direction by the urging means is the height direction, the height of the moving bearing portion when the shaft member is inserted and removed from the moving bearing portion is determined by the support position and the detaching position. The image forming apparatus according to claim 6, further comprising a height setting unit that sets the height of the moving bearing unit so as to be different. When the moving bearing portion is in the support position, the moving bearing portion includes a pressing unit that presses the moving bearing portion so as to push it toward the image carrier,
When the moving bearing portion is displaced from the support position to the disengaged position, the pressing of the moving bearing portion by the pressing means is released, and the shaft member detached from the moving bearing portion is supported by the pressing means. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. When the pressing direction by the pressing means is the height direction, when the shaft member is inserted into and removed from the moving bearing portion, the moving bearing portion has a height between the supporting position and the separating position. The image forming apparatus according to claim 8, wherein the image forming apparatus is slid in the axial direction in a state where is constant. A sheet is sandwiched between the transfer roller and the image carrier, and the sheet is moved by the rotation of the image carrier.
The image forming apparatus according to claim 1, wherein the transfer roller rotates in conjunction with the movement of the sheet by a frictional force generated between the transfer roller and the sheet. The shaft member of the transfer roller is provided with a gear member for transmitting power from the outside to the transfer roller, and the gear member is provided between the pair of bearing portions in the axial direction. The image forming apparatus according to claim 1, wherein the image forming apparatus is provided. The gear member is disposed only on one end side of the shaft member, and only the bearing portion on the side where the gear member is provided is configured as the moving bearing portion of the pair of bearing portions. The image forming apparatus according to claim 11. Of the pair of bearing portions, only one of the bearing portions is the moving bearing portion, and an electrode portion for applying a voltage to the shaft member is connected to the other bearing portion side. The image forming apparatus according to claim 1. Of the pair of bearing portions, only one of the bearing portions is the moving bearing portion, and the other bearing portion is configured to be displaceable so that the insertion direction of the shaft member is changed. The image forming apparatus according to any one of claims 1 to 13. The image forming apparatus changes the direction of a sheet supplied from one end side in the longitudinal direction of the sheet feeding cassette toward the other end side, and sends the sheet to the transfer roller side disposed above the sheet feeding cassette. A direction change part,
A second direction changing portion that changes the direction of the paper that has passed through the transfer roller toward the one end side and sends the paper to the paper discharge portion side disposed above the transfer roller;
15. The image forming apparatus according to claim 1, further comprising: A process cartridge that includes at least the image carrier and is configured to be detachable from the apparatus main body;
The apparatus main body is formed with an accommodating portion for accommodating the process cartridge, and an opening communicating with the accommodating portion is formed on one end side of the apparatus main body, and the process cartridge is interposed through the opening. Is detachable,
The transfer roller is configured to be exposed to the accommodating portion side in a state where the process cartridge is detached from the apparatus main body portion, and is detached from the apparatus main body portion by being separated to the accommodating portion side in the exposed state. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. 17. The image forming apparatus according to claim 16, wherein the transfer roller is detached from the apparatus main body in a direction substantially perpendicular to the axial direction to be separated from the storage unit. The image forming apparatus according to claim 16, wherein a direction in which the process cartridge is removed from the housing portion is a direction substantially orthogonal to the axial direction.

Images