JP2013250366A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of easily carrying out both of exchanging of an intermediate transfer belt or a secondary transfer roller and a jam processing.SOLUTION: An image forming apparatus includes: a body housing 2 having an opening 2A; a photoreceptor drum 61 arranged inside the body housing 2 and carrying a developer image; and an intermediate transfer unit 7. The intermediate transfer unit 7 integrally having an intermediate transfer belt 73 which is at least hung between a first roller 71 and a second roller 72 for transferring the developer image transferred from the photoreceptor drum 61 to paper and a secondary transfer roller 75 arranged to hold the intermediate transfer belt 73 between the first roller 71 integrally and they are composed to be attachable to/detachable from the body housing 2 through the opening 2A. The second transfer roller 75 is composed to be movable between a position of contact where contact is made with the intermediate transfer belt 73 and a separated position where the roller is separated from the intermediate transfer belt 73.

Description

  The present invention relates to an image forming apparatus having an intermediate transfer belt and a secondary transfer roller.

  2. Description of the Related Art Conventionally, an intermediate transfer type image forming apparatus including a transfer unit including an intermediate transfer belt formed of an endless belt and a secondary transfer roller that faces and contacts the intermediate transfer belt is known (see Patent Document 1). ). In the image forming apparatus of Patent Document 1, since the intermediate transfer belt is provided in the main body case and the secondary transfer roller is provided in a cover that can be opened and closed with respect to the main body case, the secondary transfer roller can be opened by opening the cover. Since it is separated from the intermediate transfer belt, it is possible to easily perform processing (jam processing) when a sheet is jammed between the intermediate transfer belt and the secondary transfer roller.

JP 2009-139495 A

  By the way, since the performance of the intermediate transfer belt and the secondary transfer roller deteriorates due to long-term use, a configuration that can be replaced in the same manner as a process cartridge is desired. However, in the conventional configuration, it is necessary to remove the intermediate transfer belt from the main body case and replace it with a new one, and further remove the secondary transfer roller from the cover and replace it with a new one. was there.

  The present invention has been made in view of the above background, and an object thereof is to provide an image forming apparatus capable of easily performing both replacement and jamming of an intermediate transfer belt and a secondary transfer roller.

In order to achieve the above object, an image forming apparatus of the present invention includes an apparatus main body having an opening, an image carrier disposed in the apparatus main body for carrying a developer image, and an intermediate transfer unit.
The intermediate transfer unit is bridged between at least the first roller and the second roller, and the intermediate transfer belt between the first roller and the intermediate transfer belt that transfers the developer image transferred from the image carrier to the recording sheet. It has a secondary transfer roller disposed so as to sandwich the belt, and is configured to be detachable from the apparatus main body through the opening.
The secondary transfer roller is configured to be movable between a contact position that contacts the intermediate transfer belt and a separation position that is separated from the intermediate transfer belt.

  According to this configuration, since the intermediate transfer belt and the secondary transfer roller can be integrally attached to and detached from the apparatus main body, compared with a configuration in which the intermediate transfer belt and the secondary transfer roller are individually replaced, The transfer belt and the secondary transfer roller can be easily replaced. In addition, when a sheet or the like is jammed between the intermediate transfer belt and the secondary transfer roller, the secondary transfer roller can be separated from the intermediate transfer belt, so that jam processing can be easily performed.

The image forming apparatus described above can be configured to include a cover that is movable between a closed position that covers the opening and an open position that exposes the opening with respect to the apparatus main body.
In this case, the secondary transfer roller can be configured to move from the contact position to the separation position in conjunction with the movement of the cover from the closed position to the open position.

  According to this, since the secondary transfer roller can be separated from the intermediate transfer belt at the same time by opening the cover, the operability during the jam processing can be improved.

  In the above-described image forming apparatus, the intermediate transfer unit or the cover may include a first biasing member that biases the secondary transfer roller toward the first roller at least when the cover is in the closed position.

  According to this, in the configuration in which the intermediate transfer unit has the first biasing member, the first biasing member and the secondary transfer roller are compared with the configuration in which the first biasing member is provided separately from the intermediate transfer unit. Since the positional accuracy can be improved, the secondary transfer roller at the contact position can be urged toward the first roller with high accuracy. Further, in the configuration in which the cover has the first urging member, since the pressure contact between the secondary transfer roller and the intermediate transfer belt can be released by opening the cover, the operability during the jam processing can be improved. .

In the above-described image forming apparatus, the first urging member can be provided in the intermediate transfer unit so as to release the urging of the secondary transfer roller when the cover is in the open position.
In this case, the cover may be configured to have a pressing portion that presses the first urging member so that the first urging member urges the secondary transfer roller when in the closed position.

  According to this, since the secondary transfer roller can be pressed against the intermediate transfer belt by closing the cover, the operability after the jam processing can be improved.

In the image forming apparatus described above, the intermediate transfer unit may include a roller guide member that supports the secondary transfer roller so as to be movable between the contact position and the separation position.
The roller guide member can be configured such that the end on the opposite side to the first roller side is positioned below the end on the first roller side in a state where the intermediate transfer unit is mounted on the apparatus main body. .
In this case, the secondary transfer roller can be configured to be movable to the separation position by its own weight along the roller guide member.

  According to this, since the secondary transfer roller can be automatically separated from the intermediate transfer belt when the cover is opened (or after the cover is opened), the operability during the jam processing can be improved. . Further, since a mechanism for separating the secondary transfer roller other than the roller guide member can be omitted, the configuration of the intermediate transfer unit and the image forming apparatus can be simplified and downsized.

In the image forming apparatus described above, the intermediate transfer unit may include a second urging member that urges the secondary transfer roller toward the separation position.
In this case, when the cover is in the closed position, the urging force of the second urging member is smaller than the urging force of the first urging member.

  According to this, when the cover is in the open position, the secondary transfer roller can be reliably separated from the intermediate transfer belt, so that jam processing can be easily performed. When the cover is in the closed position, the urging force of the second urging member is smaller than the urging force of the first urging member, so that the second urging member is intermediate between the secondary transfer roller by the first urging member. It does not interfere with the pressure contact with the transfer belt.

In the above-described image forming apparatus, the first urging member can be provided in the intermediate transfer unit.
In this case, the cover may have a roller moving mechanism that moves at least the secondary transfer roller at the contact position to the separation position when moving from the closed position to the open position.
As an example, when the first biasing member is provided so as to constantly bias the secondary transfer roller, the roller moving mechanism is engaged with the secondary transfer roller when moving the cover from the closed position to the open position. Thus, it is possible to include an engaging portion that moves the secondary transfer roller at the contact position to the separation position.

  According to this, since the secondary transfer roller can be separated from the intermediate transfer belt by opening the cover, the operability during the jam processing can be improved.

  In the image forming apparatus described above, the intermediate transfer unit may include a roller guide member that supports the secondary transfer roller so as to be movable between the contact position and the separation position.

  According to this, the secondary transfer roller can be smoothly moved by the roller guide member.

  In the above-described image forming apparatus, the roller guide member may be configured to extend in parallel to the direction connecting the rotation axis of the secondary transfer roller and the rotation axis of the first roller at the contact position.

  According to this, since the rotation shaft of the secondary transfer roller can be translated along the direction of approaching and separating from the rotation shaft of the first roller, the secondary transfer roller can be moved more smoothly. . Further, the secondary transfer roller at the contact position can be urged toward the first roller with high accuracy by the first urging member.

  In the image forming apparatus described above, the intermediate transfer unit may include a sheet guide member that guides the recording sheet between the intermediate transfer belt and the secondary transfer roller.

  According to this, compared with a configuration in which the sheet guide member is provided separately from the intermediate transfer unit, the positional accuracy between the nip portion between the intermediate transfer belt and the secondary transfer roller and the sheet guide member is improved. Can do. As a result, the recording sheet can be accurately guided between the intermediate transfer belt and the secondary transfer roller.

  In the image forming apparatus described above, the intermediate transfer unit may have a conductive member that suppresses peeling discharge when the recording sheet is separated from the intermediate transfer belt.

  According to this, as compared with the configuration in which the conductive member is provided separately from the intermediate transfer unit, the positional accuracy between the recording sheet carried out from between the intermediate transfer belt and the secondary transfer roller and the conductive member is improved. Can do. Thereby, peeling discharge can be suppressed effectively.

  According to the present invention, both the replacement of the intermediate transfer belt and the secondary transfer roller and the jam processing can be easily performed.

1 is a diagram illustrating a schematic configuration of a color printer as an example of an image forming apparatus. FIG. 2A is a perspective view of an intermediate transfer unit according to the first embodiment, and is a diagram illustrating a state where a secondary transfer roller is in a contact position, and a diagram illustrating a state where a secondary transfer roller is in a separated position. is there. FIG. 4 is a diagram illustrating a state when an intermediate transfer unit is attached to and detached from a main body housing. FIG. 4A is an enlarged view of the vicinity of the rear part of the intermediate transfer unit, and is a diagram illustrating a state where the rear cover is in a closed position, and a diagram illustrating a state where the rear cover is in an open position. FIG. 4 is an enlarged perspective view of the rear portion of the intermediate transfer unit, and is a diagram showing a state where the secondary transfer roller is in a contact position and a diagram showing a state where the secondary transfer roller is in a separated position. FIG. 7 is an enlarged view of the vicinity of the rear portion of the intermediate transfer unit during paper conveyance. FIG. 9A is an enlarged view of the vicinity of the rear portion of the intermediate transfer unit according to the second embodiment, and is a diagram illustrating a state where the rear cover is in a closed position, and a diagram illustrating a state where the rear cover is in an open position. FIG. 7A is an enlarged perspective view of the rear part of the intermediate transfer unit according to the second embodiment, and is a diagram illustrating a state where the secondary transfer roller is in a contact position and a diagram illustrating a state where the secondary transfer roller is in a separated position. b).

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, a schematic configuration of the color printer 1 as an example of an image forming apparatus will be described, and then a detailed configuration of a characteristic part (mainly, the intermediate transfer unit 7) of the present invention will be described. In the following description, the direction will be described with reference to the user who uses the color printer 1. That is, the right side in FIG. 1 is “front”, the left side is “rear”, the front side is “left”, and the back side is “right”. Also, the vertical direction in FIG.

<Schematic configuration of color printer>
As shown in FIG. 1, the color printer 1 includes a main body housing 2 as an example of an apparatus main body, a rear cover 21 as an example of a cover, a paper feeding unit 3 that supplies paper S, and a supplied paper S. It mainly includes an image forming unit 4 that forms an image. The main body housing 2 has an opening 2A provided at the rear and a paper discharge tray 22 provided at the top.

  The rear cover 21 is a cover that opens and closes the opening 2 </ b> A, and is provided at the rear portion of the main body housing 2. More specifically, the rear cover 21 rotates the upper portion about the lower rotation shaft 21A, thereby exposing the main body housing 2 to the closed position (see FIG. 1) covering the opening 2A and the opening 2A. It is provided so as to be movable between an open position (see FIG. 3).

  The paper feeding unit 3 is provided in the lower part of the main body housing 2, and feeds the paper S as an example of a recording sheet, and supplies the paper S from the paper feeding tray 31 to the image forming unit 4. A supply mechanism 32 is mainly provided. The sheets S in the sheet feed tray 31 are separated one by one by the supply mechanism 32 and supplied to the image forming unit 4.

  The image forming unit 4 mainly includes an exposure unit 5, four process units 6, an intermediate transfer unit 7, and a fixing unit 8.

  The exposure unit 5 is provided in the upper part of the main body housing 2 and includes a laser light source, a polygon mirror, a plurality of lenses, a plurality of reflecting mirrors, and the like (not shown). The laser light emitted from the laser light source based on the image data is reflected by a polygon mirror or a reflecting mirror or passes through a lens, and is scanned at high speed on the surface of each photosensitive drum 61 (see the chain line).

  The process unit 6 is arranged side by side between the paper feed tray 31 and the exposure unit 5 in the main body housing 2, and each includes a photosensitive drum 61 as an example of an image carrier and a charger 62. And a developing device 63. The developing device 63 includes a developing roller, a supply roller, a layer thickness regulating blade, a toner accommodating portion that accommodates toner (developer), and the like, in which reference numerals are omitted.

  The intermediate transfer unit 7 is disposed between the paper feed tray 31 and the process unit 6 in the main body housing 2, and includes a first roller 71, a second roller 72, an intermediate transfer belt 73, and four primary transfer units. It mainly has a roller 74 and a secondary transfer roller 75. The intermediate transfer belt 73 is stretched between the first roller 71 and the second roller 72, and the upper surface is disposed to face the four photosensitive drums 61. The primary transfer roller 74 is disposed opposite to the photosensitive drum 61 so as to sandwich the intermediate transfer belt 73 with the photosensitive drum 61, and the secondary transfer roller 75 is intermediately transferred with the first roller 71. The first roller 71 is disposed so as to sandwich the belt 73.

  The fixing unit 8 is provided above the secondary transfer roller 75 in the main body housing 2, and mainly includes a heating roller 81 and a pressure roller 82 that is disposed opposite to the heating roller 81 and presses the heating roller 81. doing.

  In such an image forming unit 4, the surface of the photosensitive drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser light from the exposure unit 5, so that the photosensitive drum 61 is exposed. An electrostatic latent image based on the image data is formed on the top. Then, toner is supplied from the developing device 63 to the surface of the photosensitive drum 61 on which the electrostatic latent image is formed, so that the electrostatic latent image is visualized and the toner image (development) is formed on the photosensitive drum 61. Agent image) is carried.

  The toner images carried on the respective photosensitive drums 61 are sequentially superimposed and transferred from the respective photosensitive drums 61 onto the intermediate transfer belt 73. Then, the sheet S conveyed from the sheet feeding unit 3 is conveyed between the intermediate transfer belt 73 and the secondary transfer roller 75, whereby the toner image on the intermediate transfer belt 73 is transferred to the sheet S. The sheet S on which the toner image has been transferred is conveyed between the heating roller 81 and the pressure roller 82 so that the toner image is thermally fixed, and then discharged from the main body housing 2 onto the discharge tray 22. .

<Detailed configuration of intermediate transfer unit>
As shown in FIG. 2A, the intermediate transfer unit 7 includes a pair of right and left as an example of the frame member 70 and the first urging member in addition to the intermediate transfer belt 73 and the secondary transfer roller 75 described above. Coil spring 76 (only one is shown), a torsion spring 77 as an example of a second urging member, a sheet guide member 78 (see FIG. 3), and a static elimination needle 79 (see FIG. 6) as an example of a conductive member. Have.

  The frame member 70 is a member that integrally supports the intermediate transfer belt 73, the secondary transfer roller 75, the springs 76, 77, and the like, and connects the pair of left and right side frames 70A and the front portions of the left and right side frames 70A. The connecting frame 70B is mainly included. As shown in FIG. 3, the first roller 71, the second roller 72, the primary transfer roller 74, and the secondary transfer roller 75 are supported rotatably with respect to the left and right side frames 70A, respectively.

  The frame member 70 is slidable substantially in the front-rear direction with respect to the main body housing 2 when the rear cover 21 is in the open position with the intermediate transfer belt 73 and the secondary transfer roller 75 integrally supported, and , And is detachably supported through the opening 2A. Accordingly, the intermediate transfer unit 7 is configured to be replaceable with respect to the main body housing 2. Although not described in detail, in this embodiment, the frame member 70 (intermediate transfer unit 7) is shown in FIG. 1 so that the intermediate transfer belt 73 does not rub against the surface of the photosensitive drum 61 when the frame member 70 is attached or detached. The intermediate transfer belt 73 is supported so as to slide forward and backward after moving downward from the state and separating the intermediate transfer belt 73 from the photosensitive drum 61.

  As shown in FIG. 4, a roller guide part 110 as an example of a roller guide member is provided at the rear part of each side frame 70A (only one is shown).

  The roller guide part 110 is mainly between a contact position (see (a)) where the secondary transfer roller 75 is in contact with the intermediate transfer belt 73 and a separation position (see (b)) which is separated from the intermediate transfer belt 73. It is a guide that is supported so as to be movable. More specifically, the roller guide portion 110 includes a pair of upper and lower guide walls 111 extending obliquely downward and rearward from the rear portion of the side frame 70A in a state (posture) in which the intermediate transfer unit 7 is attached to the main body housing 2. It is formed in a substantially U shape in a side view mainly including a rear wall 112 that connects rear end portions of the upper and lower guide walls 111.

  The upper and lower guide walls 111 support the bearing member 120 that rotatably supports the rotation shaft 75 </ b> A of the secondary transfer roller 75 so that the bearing member 120 can move in the direction toward or away from the first roller 71. Is movably supported between the contact position and the separation position. Since each guide wall 111 extends obliquely downward and rearward from the rear portion of the side frame 70A, an end portion (rear end portion) opposite to the first roller 71 side is on the first roller 71 side. It is located below the end (front end). The guide wall 111 (specifically, the surface that guides the bearing member 120) connects the rotation center of the rotation shaft 75A of the secondary transfer roller 75 at the contact position and the rotation center of the rotation shaft 71A of the first roller 71. It extends substantially parallel to the direction (see the chain line PL).

  In addition to the bearing member 120, a pressing member 130 is disposed in the roller guide portion 110 (between the upper and lower guide walls 111). The pressing member 130 has a substantially T shape in side view, and includes a plate-like support portion 131 that supports the rear end of the coil spring 76 and an extension portion 132 that extends substantially rearward from the rear surface of the support portion 131. It is comprised. In the pressing member 130, the support portion 131 is disposed between the upper and lower guide walls 111, and the extending portion 132 is inserted into a through hole 113 (see FIG. 5) provided in the rear wall 112 of the roller guide portion 110. Thus, like the bearing member 120, the bearing member 120 is supported so as to be movable in the direction of approaching or separating from the first roller 71.

  The coil spring 76 is disposed between the upper and lower guide walls 111 and between the support portion 131 of the pressing member 130 and the bearing member 120. Although details will be described later, the coil spring 76 of the present embodiment biases the secondary transfer roller 75 toward the first roller 71 by being compressed when the rear cover 21 shown in FIG. 4A is in the closed position. When the rear cover 21 shown in FIG. 4B is in the open position, it is provided in the intermediate transfer unit 7 so as to have a natural length (a fully extended state) and release the bias of the secondary transfer roller 75. .

  The roller guide portion 110, the bearing member 120, the pressing member 130, and the coil spring 76 described above are provided so as to be substantially bilaterally symmetric on the left and right sides of the secondary transfer roller 75, respectively. The left and right roller guide portions 110 also function as handles that are gripped by the user when the intermediate transfer unit 7 is attached to and detached from the main body housing 2.

  As shown in FIGS. 5A and 5B, one torsion spring 77 is provided on the right end side of the secondary transfer roller 75 (see also FIG. 2). More specifically, the torsion spring 77 constantly biases the bearing member 120 on the right side of the secondary transfer roller 75 toward substantially rearward (in the direction of the arrow in the drawing), thereby biasing the secondary transfer roller 75 toward the separated position. It is provided in the intermediate transfer unit 7 so as to urge. As shown in FIG. 5A, when the rear cover 21 is in the closed position, in other words, when the secondary transfer roller 75 is biased toward the first roller 71 (substantially forward) by the coil spring 76, the torsion spring 77 is set so that the biasing force is sufficiently smaller than the biasing force of the coil spring 76.

  As shown in FIG. 6, the seat guide member 78 is a pair of plate-like members provided so as to be spanned between the left and right side frames 70 </ b> A with a predetermined interval in the front-rear direction, and passes between them. The sheet S to be guided is guided between the intermediate transfer belt 73 and the secondary transfer roller 75. The sheet guide member 78 conveys the leading edge of the paper S supplied from the paper feeding unit 3 toward the intermediate transfer belt 73 (first roller 71). In other words, the leading edge of the paper S is first transferred to the intermediate transfer belt. 73 so as to be in contact with 73.

  As a result, the leading edge of the paper S supplied from the paper feeding unit 3 contacts the intermediate transfer belt 73 and then rotates between the intermediate transfer belt 73 and the secondary transfer roller 75 by the rotation of the intermediate transfer belt 73. Guided. Then, the toner on the intermediate transfer belt 73 is attracted to the sheet S by the potential difference between the sheet S conveyed so as to stick to the intermediate transfer belt 73 and the secondary transfer roller 75 to which a transfer bias is applied. The toner image on the intermediate transfer belt 73 is transferred onto the paper S.

  The static elimination needle 79 is a conductive needle-like member provided on the downstream side of the nip portion between the intermediate transfer belt 73 and the secondary transfer roller 75, and the tip (front end) thereof is the back surface (toner) of the paper S. It is disposed so as to face a surface on the opposite side to the surface on which the image is transferred with a predetermined interval. The static elimination needle 79 is connected to the ground, and the sheet S is separated from the intermediate transfer belt 73 by releasing static electricity accumulated on the sheet S carried out between the intermediate transfer belt 73 and the secondary transfer roller 75. Suppresses peeling discharge.

<Effects of color printer>
Next, the operation and effect of the color printer 1 according to the present embodiment will be described while explaining the operation of the color printer 1, mainly the operation when the rear cover 21 is opened and closed.

  As shown in FIG. 4A, when the rear cover 21 is in the closed position, the coil spring 76 is pushed between the bearing member 120 that rotatably supports the secondary transfer roller 75 and the support portion 131 of the pressing member 130. Since it is shrunk, the secondary transfer roller 75 in the contact position is urged toward the intermediate transfer belt 73 (first roller 71) via the bearing member 120 by returning to the original shape. As a result, the secondary transfer roller 75 and the intermediate transfer belt 73 are pressed against each other, so that the sheet S can be conveyed between the secondary transfer roller 75 and the intermediate transfer belt 73.

  As shown in FIG. 4B, when the rear cover 21 is opened, the restriction by the pressing portion 21B is released, so that the coil spring 76 returns to its original shape, and the support portion 131 (the pressing member 130) is moved. Push it back diagonally downward. Thereby, the protrusion amount of the extension part 132 from the rear wall 112 of the roller guide part 110 becomes large.

  When the coil spring 76 is fully extended (natural length), the secondary transfer roller 75 is interposed via the bearing member 120 so that the rear end portion of each guide wall 111 is positioned below the front end portion. And while pushing down the pressing member 130, it moves rearward and obliquely downward with its own weight. In other words, the secondary transfer roller 75 is self-weighted along the roller guide portion 110 in conjunction with the movement of the rear cover 21 from the closed position to the open position, and from the contact position shown in FIG. It moves to the separation position shown in (b).

  Here, in the present embodiment, since the roller guide portion 110 is provided on the frame member 70, the secondary transfer roller 75 can be smoothly moved from the contact position to the separation position. Particularly, in the roller guide portion 110 of the present embodiment, the guide wall 111 extends substantially parallel to the direction (chain line PL) connecting the rotation center of the secondary transfer roller 75 and the rotation center of the first roller 71. Since the rotary shaft 75A of the secondary transfer roller 75 can be translated along the direction of approaching and separating from the rotary shaft 71A of the first roller 71, the secondary transfer roller 75 can be moved more smoothly. it can.

  Further, as shown in FIGS. 5A and 5B, the intermediate transfer unit 7 has a torsion spring 77, so that the torsion spring 77 assists the movement of the secondary transfer roller 75 from the contact position to the separation position. be able to. Thus, when the rear cover 21 is in the open position, the secondary transfer roller 75 can be reliably separated from the intermediate transfer belt 73.

  If the paper S is jammed between the secondary transfer roller 75 and the intermediate transfer belt 73 after the rear cover 21 is opened, the jammed paper S is removed (jam processing is performed). In this embodiment, as shown in FIG. 4B, the secondary transfer roller 75 can be separated from the intermediate transfer belt 73, so that the pressure contact between the secondary transfer roller 75 and the intermediate transfer belt 73 is released. Thus, the jam processing can be easily performed.

  In the present embodiment, the secondary transfer roller 75 moves from the contact position to the separation position by its own weight along the roller guide portion 110 in conjunction with the movement of the rear cover 21 from the closed position to the open position. Thus, by opening the rear cover 21, the secondary transfer roller 75 can be separated from the intermediate transfer belt 73 simultaneously and automatically. Accordingly, it is possible to improve the operability at the time of jam processing as compared with a configuration that requires an operation for separating the secondary transfer roller from the intermediate transfer belt after the rear cover is opened.

  Further, in the present embodiment, the secondary transfer roller 75 is configured to be able to move to the separation position by its own weight along the roller guide portion 110. Therefore, basically, the secondary transfer roller other than the roller guide portion 110 is used. A mechanism for separating 75 is not necessary. As a result, it is possible to simplify the configuration of the intermediate transfer unit 7 and the color printer 1 and reduce the size thereof.

  On the other hand, when the intermediate transfer unit 7 is replaced after the rear cover 21 is in the open position, as shown in FIG. 3, the roller guide portion 110 that functions as a handle is gripped and pulled backward to reduce the performance. The intermediate transfer unit 7 is removed from the main body housing 2, and then a new intermediate transfer unit 7 is newly attached to the main body housing 2. In this embodiment, the intermediate transfer belt 73, the secondary transfer roller 75, and the like can be integrally attached to and detached from the main body housing 2 as one unit, so that the configuration is compared with a configuration in which the intermediate transfer belt and the secondary transfer roller are individually replaced. Thus, the intermediate transfer belt 73 and the secondary transfer roller 75 can be easily replaced.

  After the jam processing or after the new intermediate transfer unit 7 is attached to the main body housing 2, the rear cover 21 is closed. Then, as shown in FIG. 4B, first, the pressing portion 21B of the rear cover 21 comes into contact with the extending portion 132, and the rear cover 21 is further closed, so that the pressing portion 21B causes the extending portion 132 to move to the roller guide. It pushes into the part 110. As a result, the pressing member 130, the coil spring 76, and the bearing member 120 (secondary transfer roller 75) move forward and obliquely upward along the roller guide portion 110.

  Then, as shown in FIG. 4A, when the secondary transfer roller 75 comes into contact with the intermediate transfer belt 73 and reaches the contact position, the position of the bearing member 120 is regulated, so that the rear cover 21 is further closed. As a result, the coil spring 76 is compressed between the pressing member 130 and the bearing member 120. Then, when the rear cover 21 that has reached the closed position is locked in the closed position by a known locking mechanism (not shown), the coil spring 76 biases the secondary transfer roller 75 toward the first roller 71 via the bearing member 120. As a result, the secondary transfer roller 75 and the intermediate transfer belt 73 are brought into pressure contact again.

  When the rear cover 21 is in the closed position, the urging force of the torsion spring 77 shown in FIG. 5A is sufficiently smaller than the urging force of the left and right coil springs 76 (only one is shown). The press contact between the secondary transfer roller 75 and the intermediate transfer belt 73 is not hindered.

  In the present embodiment, since the roller guide portion 110 is provided, the secondary transfer roller 75 can be smoothly moved from the separated position to the contact position even when the rear cover 21 is moved from the open position to the closed position. Can be moved. Further, the guide wall 111 extends substantially parallel to the chain line PL shown in FIG. 4, and the coil spring 76 biases the rotation center of the secondary transfer roller 75 toward the rotation center of the first roller 71. Can do. As a result, it is difficult for the secondary transfer roller 75 to be acted upon by force that deviates up and down from the surface of the first roller 71 (intermediate transfer belt 73), so that the secondary transfer roller 75 can be urged with high accuracy. .

  In the present embodiment, the rear cover 21 has the pressing portion 21B that presses the coil spring 76 via the pressing member 130 so that the coil spring 76 biases the secondary transfer roller 75 when the rear cover 21 is in the closed position. Therefore, the secondary transfer roller 75 can be pressed against the intermediate transfer belt 73 simultaneously by closing the rear cover 21. Accordingly, the operability after the jam processing can be improved as compared with a configuration that requires an operation for pressing the secondary transfer roller against the intermediate transfer belt after the rear cover is closed.

  In the present embodiment, since the intermediate transfer unit 7 having the intermediate transfer belt 73 and the secondary transfer roller 75 integrally includes the coil spring 76, the coil spring 76 and the coil spring 76 are compared with the configuration in which the coil spring is provided separately. Position accuracy with the secondary transfer roller 75 can be improved. Thereby, the secondary transfer roller 75 in the contact position can be urged toward the intermediate transfer belt 73 (first roller 71) with high accuracy.

  Further, since the intermediate transfer unit 7 integrally includes the sheet guide member 78, the nip portion between the intermediate transfer belt 73 and the secondary transfer roller 75 is compared with a configuration in which the sheet guide member is provided separately. And the positional accuracy with respect to the sheet guide member 78 can be improved. Accordingly, the sheet S can be guided with high accuracy between the intermediate transfer belt 73 and the secondary transfer roller 75, and a good toner image can be transferred onto the sheet S.

  Further, since the intermediate transfer unit 7 integrally includes the static elimination needle 79, the sheet S that is carried out from between the intermediate transfer belt 73 and the secondary transfer roller 75 is compared with a configuration in which the static elimination needle is provided separately. And the positional accuracy with the front-end | tip of the static elimination needle 79 can be improved. Thereby, since peeling discharge can be suppressed effectively, the image quality fall resulting from peeling discharge can be suppressed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In the present embodiment, the same reference numerals are assigned to components that are substantially the same as those in the first embodiment, and the description thereof is omitted. In the drawings to be referred to, FIG. 7 is a view of the periphery of the right roller guide portion 110 viewed from the inside in the left-right direction, and FIG. 8 is a perspective view of the periphery of the left roller guide portion 110 viewed obliquely from the rear. It is.

  As shown in FIGS. 7A and 7B, the intermediate transfer unit 7 according to the present embodiment includes an intermediate transfer belt 73 spanned between a first roller 71 and a second roller (not shown), and a primary transfer. A roller 74, a secondary transfer roller 75, a frame member 70, a coil spring 76 as a first urging member, a sheet guide member 78, and a static elimination needle 79 are included. Incidentally, the intermediate transfer unit 7 of the present embodiment is not provided with the second urging member such as the torsion spring 77 of the first embodiment described above.

  As shown in FIGS. 7 and 8, the frame member 70 (each side frame 70A) has a pair of upper and lower guide walls 111, a rear wall 114 connecting the rear ends of the upper and lower guide walls 111, and upper and lower portions, respectively. The roller guide portion 110 mainly includes a guide wall 111 and a side wall 115 that connects the outer ends of the rear wall 114 in the left-right direction. The coil spring 76 and the bearing member 220 are provided between the upper and lower guide walls 111, respectively. Is arranged. The rear wall 114 is not provided with the through hole 113 unlike the rear wall 112 of the first embodiment described above, and the coil spring 76 is interposed between the rear wall 114 and the bearing member 220 via the bearing member 220. The secondary transfer roller 75 is always urged toward the first roller 71.

  As shown in FIGS. 8A and 8B, the bearing member 220 rotatably supports the rotating shaft 75 </ b> A (see FIG. 7) of the secondary transfer roller 75 and from a through hole 116 provided in the side wall 115. A bearing portion 221 disposed so as to protrude, an extending portion 222 extending downward from an end on the outer side in the left-right direction of the bearing portion 221, and an outer side from a lower portion of the outer surface in the left-right direction of the extending portion 222 It mainly has an engaged portion 223 that protrudes toward it.

  The through hole 116 of the side wall 115 is a long hole that is long in the direction of approaching and separating from the first roller 71, and the bearing member 220 (bearing portion 221) moves mainly along the through hole 116, The next transfer roller 75 is movable between a contact position shown in each drawing (a) and a separation position shown in each drawing (b).

  As shown in FIG. 7, the rear cover 21 of the present embodiment separates the secondary transfer roller 75 at the contact position when moving from the closed position shown by the solid line in FIG. 7A to the open position shown in FIG. It has a roller moving mechanism (engaging portion 210) that moves it to a position. Specifically, each of the engaging portions 210 is located at a position corresponding to the engaged portion 223 of the bearing member 220 in the left-right direction on the front surface of the rear cover 21 when the rear cover 21 is in the closed position. It protrudes toward The engaging portion 210 is provided at the front end so as to connect the inclined surface 211 inclined obliquely from the upper rear to the lower front, and the rear end of the inclined surface 211 and the front surface of the rear cover 21. And a restricting surface 212 extending mainly.

  In the present embodiment, since the coil spring 76 constantly biases the secondary transfer roller 75, the secondary transfer roller 75 is moved to the intermediate transfer belt 73 when the rear cover 21 indicated by a solid line in FIG. It is in pressure contact. 7A, when the rear cover 21 is opened, first, the inclined surface 211 of the engaging portion 210 comes into contact with the engaged portion 223 of the bearing member 220.

  When the rear cover 21 is further opened, the engaged portion 223 is pushed substantially rearward by the inclined surface 211, and the bearing portion 221 (bearing member 220) moves along the through hole 116 against the urging force of the coil spring 76. The secondary transfer roller 75 moves from the contact position to the separation position by moving obliquely downward. Then, as shown in FIG. 7B, when the rear cover 21 is in the open position, the regulating surface 212 is engaged with the secondary transfer roller 75 via the engaged portion 223, so that the bearing member 220 is moved. Thus, the secondary transfer roller 75 is regulated to the separated position, and the pressure contact between the secondary transfer roller 75 and the intermediate transfer belt 73 (first roller 71) is maintained.

  As described above, also in the present embodiment, by opening the rear cover 21, the secondary transfer roller 75 can be separated from the intermediate transfer belt 73 without performing other operations, so that the operability during the jam processing is improved. Can be made.

  On the other hand, if the rear cover 21 is closed after jamming or the like, the bearing portion 221 (bearing member 220) is forced by the biasing force of the coil spring 76 when the engagement portion 210 and the engaged portion 223 are disengaged. It moves forward and obliquely upward along the through hole 116. As a result, the secondary transfer roller 75 moves from the separated position to the contact position, and is again brought into pressure contact with the intermediate transfer belt 73 by the biasing force of the coil spring 76.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. About a concrete structure, it can change suitably in the range which does not deviate from the meaning of this invention.

  In the above embodiment, the coil spring 76 (first biasing member) is provided in the intermediate transfer unit 7, but the present invention is not limited to this, and may be provided in a cover, for example. As described above, in the configuration in which the cover has the first biasing member that biases the secondary transfer roller toward the first roller, the pressure contact between the secondary transfer roller and the intermediate transfer belt is released by opening the cover. Therefore, the operability at the time of jam processing can be improved.

  In the embodiment, the coil spring 76 (compression coil spring) is exemplified as the first urging member, and the torsion spring 77 is exemplified as the second urging member. However, any member that can perform the same function may be used. It is not limited to the type of biasing member. For example, the first urging member may be a tension coil spring or the like, and the second urging member may be an elastically deformable member such as a sponge.

  In the embodiment, the secondary transfer roller 75 is configured to move from the contact position to the separated position in conjunction with the rear cover 21 (cover) moving from the closed position to the open position. It is not limited to this. For example, the secondary transfer roller may be configured to move from the contact position to the separated position by operating a separately provided lever or the like when the cover is in the open position (after opening the cover). .

  In the embodiment, the roller guide portion 110 as the roller guide member is provided on the frame (frame member 70) of the intermediate transfer unit 7. However, the present invention is not limited to this, for example, the frame of the intermediate transfer unit. It may be configured as a separate part. Further, the specific configuration of the roller guide portion 110 (roller guide member) shown in the above embodiment is an example, and the present invention is not limited to the configuration of the above embodiment. For example, in the above-described embodiment, the guide wall 111 (surface that guides the bearing member 120) extends substantially parallel to the direction connecting the rotation shaft 75 </ b> A of the secondary transfer roller 75 and the rotation shaft 71 </ b> A of the first roller 71. However, the present invention is not limited to this. For example, at least a part of the guide surface may be curved. Further, for example, when the secondary transfer roller is supported so as to be swingable between the contact position and the separation position, the roller guide member may not be provided.

  In the second embodiment, the engaging portion 210 is exemplified as the roller moving mechanism. The roller moving mechanism (engaging portion 210) is configured to simply move the secondary transfer roller at the contact position to the separated position when the rear cover 21 is moved from the closed position to the open position. It is not limited to this. For example, the roller moving mechanism can be configured by combining the engaging portion 210 of the second embodiment and the pressing portion 21B of the first embodiment. In this case, when the cover is moved from the closed position to the open position, the secondary transfer roller at the contact position can be moved to the separated position by the engaging portion 210, and the cover is moved from the open position to the closed position. Sometimes, the secondary transfer roller in the separated position can be moved to the contact position by the pressing portion 21B.

  In the above embodiment, the sheet guide member 78 and the static elimination needle 79 (conductive member) are provided in the intermediate transfer unit 7, but the present invention is not limited to this, and may be provided in the apparatus main body, for example. Moreover, in the said embodiment, although the needle-shaped static elimination needle 79 was illustrated as an electroconductive member which suppresses peeling discharge, if the member can fulfill | perform the same function, the shape etc. will not be specifically limited. Absent. The same applies to the sheet guide member.

  In the said embodiment, although the rear cover 21 was illustrated as a cover, this invention is not limited to this. For example, when the intermediate transfer unit is configured to be detachable through an opening provided in the front portion of the apparatus main body, the cover may be a front cover. In addition, when a part of the intermediate transfer unit mounted on the apparatus main body constitutes a part of the outer wall of the apparatus main body, a cover for opening and closing the opening may be omitted.

  In the above-described embodiment, the intermediate transfer belt 73 is stretched between two rollers (the first roller 71 and the second roller 72). However, the present invention is not limited to this. It may be stretched over three or more rollers.

  In the above-described embodiment, the color printer 1 (printer) is exemplified as the image forming apparatus. However, the present invention is not limited to this. For example, the image forming apparatus is a copying machine or a multifunction machine including a document reading device such as a flat bed scanner. Also good. In the embodiment, the paper S such as plain paper or postcard is exemplified as the recording sheet. However, the present invention is not limited to this, and may be, for example, an OHP sheet.

DESCRIPTION OF SYMBOLS 1 Color printer 2 Main body housing | casing 2A Opening 7 Intermediate transfer unit 21 Rear cover 21B Press part 61 Photosensitive drum 71 1st roller 72 2nd roller 73 Intermediate transfer belt 75 Secondary transfer roller 76 Coil spring 77 Torsion spring 78 Sheet guide member 79 Static elimination Needle 110 Roller guide portion 111 Guide wall 112 Rear wall 113 Through hole 120 Bearing member 130 Press member 131 Support portion 132 Extension portion S Paper

Claims (12)

An apparatus body having an opening;
An image carrier disposed in the apparatus main body and carrying a developer image;
An intermediate transfer belt that is stretched between at least the first roller and the second roller and transfers the developer image transferred from the image carrier to a recording sheet, and the intermediate transfer belt between the first roller and the intermediate transfer belt. An intermediate transfer unit integrally having a secondary transfer roller disposed so as to be sandwiched therebetween,
The intermediate transfer unit is configured to be detachable from the apparatus main body through the opening.
The image forming apparatus, wherein the secondary transfer roller is configured to be movable between a contact position that contacts the intermediate transfer belt and a separation position that is separated from the intermediate transfer belt. A cover provided on the apparatus main body so as to be movable between a closed position covering the opening and an open position exposing the opening;
The image forming apparatus according to claim 1, wherein the secondary transfer roller is configured to move from a contact position to a separation position in conjunction with the movement of the cover from a closed position to an open position. apparatus.   3. The intermediate transfer unit or the cover includes a first urging member that urges the secondary transfer roller toward the first roller at least when the cover is in a closed position. The image forming apparatus described. The first urging member is provided in the intermediate transfer unit so as to release the urging of the secondary transfer roller when the cover is in the open position.
The said cover has a press part which presses the said 1st urging | biasing member so that the said 1st urging | biasing member urges | biases the said secondary transfer roller when it is a closed position. The image forming apparatus described. The intermediate transfer unit has a roller guide member that supports the secondary transfer roller so as to be movable between a contact position and a separation position;
In the state where the intermediate transfer unit is mounted on the apparatus main body, the roller guide member has an end portion on the opposite side to the first roller side located below the end portion on the first roller side,
5. The image forming apparatus according to claim 3, wherein the secondary transfer roller is configured to be movable to a separation position under its own weight along the roller guide member. The intermediate transfer unit has a second urging member that urges the secondary transfer roller toward the separation position,
6. The image forming apparatus according to claim 4, wherein when the cover is in a closed position, an urging force of the second urging member is smaller than an urging force of the first urging member. The first biasing member is provided in the intermediate transfer unit,
The image forming apparatus according to claim 3, wherein the cover includes a roller moving mechanism that moves at least the secondary transfer roller at the contact position to the separated position when moving from the closed position to the open position. . The first biasing member is provided to constantly bias the secondary transfer roller,
The roller moving mechanism includes an engaging portion that engages with the secondary transfer roller to move the secondary transfer roller at the contact position to the separated position when the cover is moved from the closed position to the open position. The image forming apparatus according to claim 7.   7. The intermediate transfer unit includes a roller guide member that supports the secondary transfer roller so as to be movable between a contact position and a separation position. The image forming apparatus according to claim 1.   10. The roller guide member according to claim 5, wherein the roller guide member extends parallel to a direction connecting the rotation shaft of the secondary transfer roller and the rotation shaft of the first roller at a contact position. The image forming apparatus described.   11. The intermediate transfer unit according to claim 1, further comprising a sheet guide member that guides a recording sheet between the intermediate transfer belt and the secondary transfer roller. The image forming apparatus described.   The image forming apparatus according to claim 1, wherein the intermediate transfer unit includes a conductive member that suppresses peeling discharge when the recording sheet is separated from the intermediate transfer belt.

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