JP2005172993A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably ground an intermediate transfer body relative to the main body of an image forming apparatus despite the openable structure of the intermediate transfer body. <P>SOLUTION: A contact at which the intermediate transfer body is grounded to the main body of the image forming apparatus is provided in the part where the intermediate transfer body is positioned to the position of image formation. When moving from the position of the image formation to an attached/detached position, the intermediate transfer body moves rotating around the part where the intermediate transfer body is positioned to the position of the image formation. When the intermediate transfer body moves from the attached/detached position to the position of the image formation or when it moves from the position of the image formation to the attached/detached position, the surface of the contact of the intermediate transfer body is wiped accompanying the rotating motion of the intermediate transfer body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus using an electrophotographic system, and relates to an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  FIG. 8 schematically shows an example of a conventional color image forming apparatus using an electrophotographic process, in this example, a color laser printer (see, for example, Patent Document 1).

  This color laser printer includes a process cartridge 2 serving as four image forming portions of yellow 2Y, magenta 2M, cyan 2C and black 2Bk, and an image carrier 21 (electrophotographic photosensitive member) in each process cartridge 2. This is a four-drum type (in-line) printer that obtains a full-color print image by continuously and continuously transferring the image formed on the intermediate transfer member 35, which is a second image carrier.

  At this time, if the process cartridges 2 are arranged so as to be stacked in the vertical direction, the installation area can be reduced, the merit of saving the office space is great, and it is an effective means for personalizing the color laser printer. .

  Further, the intermediate transfer body 35 is attached to the opening / closing cover 11 side of the printer, and by opening the opening / closing cover 11 and further opening the intermediate transfer body 35, the process cartridge 2 can be accessed. Can be done.

Japanese Patent Application Laid-Open No. 08-160839

  However, although the user operability is significantly improved by opening the intermediate transfer member and replacing the process cartridge or performing JAM processing, the contact failure to ground the intermediate transfer member to the image forming apparatus main body is durable. And the potential problem of compromising the reliability of the original function of the image forming apparatus.

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of stably grounding the intermediate transfer body to the main body of the image forming apparatus even if the intermediate transfer body configuration is openable.

  In order to achieve the above object, according to a first aspect of the present invention, at least one process cartridge including an electrophotographic photosensitive member detachably attached to an image forming apparatus main body is disposed, and an image on the electrophotographic photosensitive member is arranged. An intermediate transfer member for temporarily carrying a plurality of images before transferring the image onto a transfer material and transferring the images to the transfer material at once, the process cartridge and the intermediate transfer member having two positions, an image forming position and an attaching / detaching position. In the image forming apparatus, the process cartridge and the intermediate transfer body are freely movable between the image forming position and the attachment / detachment position, and the intermediate transfer body is attached to the image forming apparatus main body at the image forming position. It has a positioning part to be positioned, and has a contact point for grounding the intermediate transfer body to the image forming apparatus main body at the positioning part of the intermediate transfer body.

  According to a second aspect of the invention, in the first aspect of the invention, the intermediate transfer member has a rotation center that moves while rotating when moving from the image forming position to the attachment / detachment position, and the rotation center is the intermediate position. It is a positioning part of a transfer body.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the intermediate transfer member moves from the attachment / detachment position to the image formation position or from the image formation position to the attachment / detachment position. The intermediate transfer member contact surface is slid by the rotational movement of the intermediate transfer member, and the intermediate transfer member contact surface is scraped out.

  According to the present invention, the intermediate transfer body can be stably grounded to the image forming apparatus main body by providing the contact point for grounding the intermediate transfer body to the image forming apparatus main body at the positioning portion of the intermediate transfer body.

  Further, according to the present invention, when the intermediate transfer member moves from the image forming position to the attachment / detachment position, the intermediate transfer member has a rotation center that moves while rotating, the rotation center is a positioning portion of the intermediate transfer member, and the intermediate transfer member is attached / detached. When moving from the position to the image forming position, or moving from the image forming position to the attachment / detachment position, the intermediate transfer body contact surface is slid by the rotational movement of the intermediate transfer body, and the surface of the intermediate transfer body contact surface is scraped. In addition, the intermediate transfer member can be grounded to the image forming apparatus main body.

[Overall Description of Image Forming Apparatus]
First, the overall configuration of the color image forming apparatus will be outlined.

  FIG. 7 is an explanatory diagram of the overall configuration of a laser printer which is an embodiment of a color image forming apparatus.

  The color laser printer is developed and multiple-transferred in an image forming unit and an image forming unit composed of process cartridges 2Y, 2M, 2C, and 2Bk having an image carrier 21 that rotates at a constant speed for each color of Y, M, C, and Bk. And an intermediate transfer member 35 that holds the color image and further performs secondary transfer onto the transfer material P fed from the feeding unit. The transfer material P on which the color image is transferred is conveyed to the fixing unit 50 to fix the color image on the transfer material P, and is discharged onto a discharge tray 56 on the upper surface of the apparatus by discharge roller groups 53, 54, and 55. The four color process cartridges 2 are configured to be detachable from the printer main body.

Next, the configuration of each part of the image forming apparatus will be sequentially described in detail.
[Image carrier]
An image carrier (photosensitive drum) 21 (21Y, 21M, 21C, 21Bk) is integrally formed with a developer container 24 (24Y, 24M, 24C, 24Bk), and this process cartridge 2 (2Y, 2M, 2C). , 2Bk) is detachably supported with respect to the printer main body, and is configured such that the unit can be easily replaced according to the life of the image carrier 21. The image carrier (photosensitive drum) 21 according to this embodiment is configured by coating an organic photoconductor layer on the outside of an aluminum cylinder, and is rotatably supported by a container 24 of the image carrier 21. Further, by transmitting a driving force of a driving motor (not shown) to one end on the rear side in the drawing, the image carrier 21 is rotated counterclockwise in the drawing according to an image forming operation.
[Charging means]
The charging means 23 (23Y, 23M, 23C, 23Bk) uses a roller charging method, and charges the applied voltage uniformly on the surface of the image carrier 21 by a charging roller.
[Exposure means]
The image carrier 21 is exposed from the scanner unit 1 (1Y, 1M, 1C, 1Bk). When the image signal is applied to the laser diode, the laser diode irradiates the polygon mirror 13 (13Y, 13M, 13C, 13Bk) with the image light 12 (12Y, 12M, 12C, 12Bk) corresponding to the image signal. The polygon mirror 13 is rotated at a high speed by a scanner motor (not shown), and selectively exposes the surface of the image carrier 21 on which the image light 12 reflected by the polygon mirror 13 is rotated at a constant speed. An electrostatic latent image is formed on the body 21.
[Development means]
The developing means is composed of four process cartridges 2 that can develop each color of yellow, magenta, cyan, and black in order to visualize the electrostatic latent image. Each of the four color process cartridges 2 faces the image carrier 21 and is disposed at a position where the development sleeve 22 (22Y, 22M, 22C, 22Bk) contacts the image carrier 21 while rotating. A visible image is formed on each color toner 21.
[Intermediate transfer member]
The intermediate transfer member 35 rotates in the clockwise direction in synchronization with the outer peripheral speed of the image carrier 21 in order to multiplex-transfer the toner image on the image carrier 21 visualized by each developing device 2 during the color image forming operation. The toner image formed on the image carrier 21 is transferred to a primary transfer portion T1 (T1Y, T1M, T1C, T1Bk) which is a contact point with a primary transfer roller 34 (34Y, 34M, 34C, 34Bk) to which a voltage is applied. Multiple transfer is performed on the intermediate transfer member 35. The intermediate transfer member 35 that has undergone multiple transfer sandwiches and conveys the transfer material P by the secondary transfer roller 51 to which a voltage is applied in the secondary transfer portion T <b> 2, thereby conveying each color toner image on the intermediate transfer member 35 to the transfer material 2. Simultaneous multiple transfer.

  The intermediate transfer member (intermediate transfer belt) 35 according to this embodiment is formed of a seamless belt, and is stretched around three axes of a drive roller 31, a secondary transfer counter roller 32, and a tension roller 33. Both ends are loaded with springs, and even if the peripheral length of the intermediate transfer belt 35 changes due to temperature and humidity in the main body or changes with time, the amount of change can be absorbed.

  Guide ribs (not shown) are attached to the entire circumference of the inner side edge of the intermediate transfer member 35 with an adhesive. Further, a flange (not shown) made of resin is disposed at one end of the tension roller 33, and a guide rib (not shown) and a flange (not shown) are connected to the traveling direction of the intermediate transfer body 35. It restricts the movement in the orthogonal direction (hereinafter referred to as “shift”).

The intermediate transfer member 35 is supported by the image forming apparatus main body with the driving roller 31 as a fulcrum, and transmits the driving force of a driving motor (not shown) to one end on the rear side of the driving roller 31 to form the image on the intermediate transfer member 31. It is made to rotate clockwise according to operation | movement.
[Paper Feeder]
The sheet feeding unit feeds the transfer material P to the image forming unit, and includes a cassette 7 storing a plurality of transfer materials P, a sheet feeding roller 41, a separation pad 42, a sheet feeding guide 43, and a registration roller pair 44. Consists mainly of. At the time of image formation, the paper feed roller 41 is driven and rotated according to the image forming operation, and the transfer material P in the cassette 4 is separated and fed one by one, guided by the guide plate 43, and registered via the transport roller. 44. During the image forming operation, the registration roller 44 performs a non-rotating operation for causing the transfer material P to stand still and a rotating operation for conveying the transfer material P toward the intermediate transfer body 35 in a predetermined sequence, and is the next step. The image and the transfer material P are aligned in the transfer process.
[Secondary transfer section]
The secondary transfer portion is composed of a secondary transfer roller 51. The secondary transfer roller 51 has a metal shaft wound with a medium-resistance foamed elastic body, is movable in the vertical direction in the figure, and has a drive. The secondary transfer roller 51 is pressed against the intermediate transfer body 35 with a predetermined pressure via the transfer material P in accordance with the timing of transferring the color image to the transfer material P. At this time, a bias is simultaneously applied to the secondary transfer roller 51, and the toner image on the intermediate transfer body 35 is secondarily transferred to the transfer material P. Here, since the intermediate transfer body 35 and the secondary transfer roller 51 are respectively driven, the transfer material P sandwiched between the two is simultaneously subjected to the transfer process and at the same speed in the left direction in the figure. It is conveyed and conveyed toward the fixing device 50 as the next process by the conveyance belt 52.
[Fixing part]
The fixing unit 50 heats and fixes the toner image formed on the transfer material P via the intermediate transfer body 35 with the toner image formed by the developing means, and is a ceramic for applying heat to the transfer material P. The film guide unit 61 includes a heater 63 and a pressure roller 62 that presses the transfer material P against the film guide unit 61. That is, the transfer material P holding the toner image is conveyed by the film guide unit 61 and the pressure roller 62, and the toner is fixed to the transfer material P by applying heat and pressure.
[Image forming operation]
Next, an operation when image formation is performed by the apparatus configured as described above will be described.

  First, the sheet feeding roller 41 shown in FIG. 4 is rotated to separate one transfer material P in the sheet feeding cassette 7 and conveyed to the registration roller 44.

  On the other hand, the image carrier 21 and the intermediate transfer member 35 rotate in the direction indicated by the arrow at a predetermined outer peripheral speed V (hereinafter referred to as process speed).

  The image carrier 21 whose surface is uniformly charged by the charging means 23 is subjected to laser 12 exposure to form an image.

1: Yellow Image Formation A yellow image is formed on the image carrier 21Y by irradiating the laser image 12Y of the yellow image with the scanner unit 1Y. Simultaneously with the formation of the latent image, the yellow developing unit 22Y is driven to apply a voltage having the same polarity as the charged polarity of the image carrier 21Y so that the yellow toner adheres to the latent image on the image carrier 21Y. Perform yellow development. At the same time, the yellow toner image on the image carrier 21 is primarily transferred onto the outer periphery of the intermediate transfer member 35 at the first transfer position T1Y downstream of the developing unit. At this time, primary transfer is performed by applying a voltage having a reverse characteristic to that of the yellow toner to the intermediate transfer member 35.

2: Formation of Magenta Image Next, the scanner unit 1M starts laser 12M irradiation of the magenta image so that the leading edge of the yellow image on the outer periphery of the intermediate transfer member 35 is coincident with the latent image on the image carrier 21M. The magenta toner image is developed on the image, and the magenta toner image on the image carrier 21M is transferred onto the intermediate transfer member 35 at the first transfer position T1M.

3: Cyan Image Formation Next, the laser image 12C irradiation of the cyan image is started by the scanner unit 1C so that the outer peripheral yellow of the intermediate transfer member 35 and the leading edge of the magenta image coincide with each other, and on the image carrier 21C in the same manner as magenta. Then, the cyan toner image is developed on the latent image, and the cyan toner image on the image carrier 21C is transferred onto the intermediate transfer member 35 at the first transfer position T1C so as to be superimposed on the yellow and magenta toner images.

4: Formation of Black Image Next, irradiation of the laser 12Bk of the black image is started by the scanner unit 1B so that the leading ends of the yellow / magenta / cyan image on the outer periphery of the intermediate transfer member 35 coincide with each other. The black toner image is developed on the latent image on 21Bk, and the black toner image on the image carrier 21Bk is further transferred onto the intermediate transfer member 35 at the first transfer position T1Bk.

  The latent image formation and development and toner transfer to the intermediate transfer member 35 are performed at the primary transfer positions T1Y, T1M, T1C, and T1Bk in the order of yellow, magenta, cyan, and black, and the surface of the intermediate transfer member 35 is yellow. A full-color image composed of four types of toners, magenta, cyan, and black is formed.

  Before the transfer of the black toner to the intermediate transfer body 35 is completed, that is, before the front end of the image of the intermediate transfer body 35 that has formed the full color image after the primary transfer of the fourth color black toner reaches the secondary transfer portion T2. In addition, the transfer material P that has been waiting by the registration roller 44 is started to be transported at the same timing. At the time of image formation of each color on the four-color intermediate transfer member 35, the secondary transfer roller 51, which is waiting in the downward direction and is not in contact with the intermediate transfer member 35, is simultaneously moved upward by a cam (not shown). Then, the transfer material P is brought into pressure contact with the secondary transfer portion T2 of the intermediate transfer body 35, and simultaneously, a full-color image on the intermediate transfer body 35 is transferred to the transfer material P by applying a bias having reverse characteristics to the toner to the secondary transfer roller 51. Transfer all four colors at once. The transfer material P that has passed through the secondary transfer portion T2 is peeled off from the intermediate transfer body 35, conveyed to the fixing portion 50, and after toner fixing, the transfer material P is placed on the discharge tray 56 at the upper part of the main body via the discharge roller pairs 53, 54, and 55. The image is discharged with the image surface facing downward, and the image forming operation ends.

  FIG. 6 is a schematic sectional view of the main body of the image forming apparatus that best represents the opening / closing operation of the opening / closing cover, the process cartridge, and the intermediate transfer member in the present invention.

  As shown in FIG. 6, the opening / closing cover 11 of the main body has a rotation center 11a on the lower front side of the color image forming apparatus.

  The intermediate transfer member 35 is attached to the opening / closing cover 11 side of the printer. Reference numeral 3 denotes a cartridge holding member that integrally holds the process cartridges 2Y, 2M, 2C, and 2Bk. The pivot point 3 a of the cartridge holding member 3 is provided above the apparatus, and forms a link mechanism by the cartridge holding member connecting rod 16 and the opening / closing cover connecting rod 17 and is connected to the opening / closing cover 11.

  When the open / close cover 11 is closed, the cartridge holding member 3 is pushed in by the open / close cover connecting rod 17 and the cartridge holding member connecting rod 16 connected to the open / close cover 11 and is held by the mounting holding member 18 and the holding spring 19. It has become. At that time, each process cartridge 2 is positioned by pressing a bearing of the process cartridge 2 into a positioning hole (not shown) provided in the image forming apparatus main body. As described above, the positioning of the process cartridge 2 is performed on the image forming apparatus main body side separately from the cartridge holding member 3, so that the cartridge holding member 3 functions only as a rough guide for the process cartridge 2. Since it is good, the operator may perform rough operations even when the process cartridge 2 is mounted.

  Next, when opening the opening / closing cover 11, the opening / closing cover connecting rod 17 rotates counterclockwise around the connecting point 11 b with the opening / closing cover 11, and accordingly, the cartridge holding member connecting rod 16 is also connected to the cartridge holding member 3. It rotates counterclockwise around the point 3b.

  Further, when the opening / closing cover 11 is opened, the cartridge holding member 3 starts to rotate around the pivot point 3a from the time when the opening / closing cover connecting rod 17 and the cartridge holding member connecting rod 16 become straight, and opens to the fully open position. Further, since the drive of the process cartridge is released by a drive release mechanism of the process cartridge 2 (not shown) that is linked separately from the movement of the opening / closing cover 11, the process cartridge 2 can be moved in conjunction with the movement of the opening / closing door.

  As described above, in conjunction with the opening operation of the opening / closing cover 11, the intermediate transfer body 35 is separated from the process cartridge 2, and the process cartridge 2 is moved so that it can be attached and detached.

  Next, FIG. 1 shows a schematic cross-sectional view of the positioning configuration of the intermediate transfer member at the image forming position that best represents the configuration of the present invention. 2 to 4 are schematic sectional views showing a process in which the intermediate transfer member moves from the image forming position to the attaching / detaching position, and FIG. 5 is a detailed view of the contact portion in FIG.

  In FIG. 1, the intermediate transfer member 35 is provided with a driving roller holding member provided on the image forming apparatus main body side by a driving roller 35b for driving the intermediate transfer member 35 by an urging means SP provided on the opening / closing cover (not shown). 38, the positioning portion 35a on the intermediate transfer member side is fitted to the positioning portion 36 on the image forming apparatus main body side, and is positioned at a position facing the process cartridges 2Y, 2M, 2C, 2Bk.

  Reference numeral 37 denotes a contact for grounding the intermediate transfer body 35 to the image forming apparatus main body, and is attached to the positioning portion 36 on the image forming apparatus main body side. Further, the intermediate transfer member side positioning portion 35 a is formed of a conductive member, and conduction in the intermediate transfer member 35 is concentrated on the intermediate transfer member side positioning portion 35 a, and the intermediate transfer member side positioning portion 35 a is in pressure contact with the contact 37. Thus, the intermediate transfer member 35 is grounded to the image forming apparatus main body.

  When moving from the image forming position shown in FIG. 1 to the attachment / detachment position (FIG. 4), first, as shown in FIG. 2, when the opening / closing cover is pulled (not shown), the intermediate transfer body 35 is positioned on the intermediate transfer body side. Remains the center of rotation while being fitted to the positioning portion 36 on the image forming apparatus main body side, and the drive of the intermediate transfer member 35 is released. At this time, as shown in FIG. 5, the surface of the contact 37 slides with the positioning portion 35a on the intermediate transfer body side by the rotational movement of the positioning portion 35a on the intermediate transfer body side. Even if the toner falls or an oxide film is formed, it can be scraped off and always kept in a clear state. Therefore, even if the durability of the image forming apparatus main body progresses, the intermediate transfer member 35 can be stably grounded to the image forming apparatus main body.

  Further, when the opening / closing cover is opened, as shown in FIG. 3, the intermediate transfer member 35 releases the fitting between the positioning portion 35a on the intermediate transfer member side and the positioning portion 36 on the image forming apparatus main body side. It moves to the attachment / detachment position shown in FIG.

  On the other hand, when the intermediate transfer body 35 moves from the attachment / detachment position to the image forming position, the reverse movement occurs, and after the positioning section 35a on the intermediate transfer body side is fitted with the positioning section 36 on the image forming apparatus main body side, As in the case of moving from the image forming position to the attaching / detaching position, the intermediate transfer member 35 rotates and moves while the positioning portion 35a on the intermediate transfer member side is fitted to the positioning portion 36 on the image forming apparatus main body side. Wiping.

  With the above configuration, the contact can be wiped twice by opening and closing the open / close cover once, and the reliability of the contact of the intermediate transfer member can be further improved.

  The present invention can be applied to an image forming apparatus such as a copying machine, a printer, and a facsimile apparatus using an electrophotographic system.

FIG. 3 is a schematic cross-sectional view of an intermediate transfer body positioning configuration at an image forming position according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view illustrating a process of moving an intermediate transfer member and a process cartridge according to an embodiment of the present invention from an image forming position to an attaching / detaching position. FIG. 4 is a schematic cross-sectional view illustrating a process of moving an intermediate transfer member and a process cartridge according to an embodiment of the present invention from an image forming position to an attaching / detaching position. FIG. 4 is a schematic cross-sectional view illustrating a process of moving an intermediate transfer member and a process cartridge according to an embodiment of the present invention from an image forming position to an attaching / detaching position. FIG. 4 is a schematic cross-sectional view illustrating a process of moving an intermediate transfer member and a process cartridge according to an embodiment of the present invention from an image forming position to an attaching / detaching position. FIG. 5 is a schematic cross-sectional view relating to an opening / closing operation of an opening / closing cover of the image forming apparatus according to the embodiment of the present invention. 1 is a schematic cross-sectional view of an image forming apparatus main body according to an embodiment of the present invention. It is a schematic sectional drawing of the conventional image forming apparatus main body.

Explanation of symbols

2 Process cartridge 3 Process cartridge holding member 3a Center of rotation of process cartridge holding member 16 Cartridge holding member connecting rod 17 Opening / closing door connecting rod 18 Mounting holding member 19 Holding spring 35 Intermediate transfer member (intermediate transfer belt)
35a Positioning portion on the intermediate transfer member side 35b Driving roller 36 Positioning portion on the image forming apparatus main body side 37 Contact point 38 Driving roller holding member

Claims (3)

At least one process cartridge including an electrophotographic photosensitive member that is detachably attached to the image forming apparatus main body is disposed, and a plurality of images are temporarily carried before the image on the electrophotographic photosensitive member is transferred to a transfer material. And an intermediate transfer member for batch transfer to a transfer material, the process cartridge and the intermediate transfer member have two positions, an image forming position and an attachment / detachment position, and the process cartridge and the intermediate transfer member are In an image forming apparatus that is freely movable between an image forming position and the attaching / detaching position,
The intermediate transfer body has a positioning portion that is positioned on the image forming apparatus main body at an image forming position, and has a contact point that grounds the intermediate transfer body to the image forming apparatus main body at the positioning portion of the intermediate transfer body. Image forming apparatus.   2. The intermediate transfer member has a rotation center that moves while rotating when the intermediate transfer member moves from an image forming position to an attachment / detachment position, and the rotation center is a positioning portion of the intermediate transfer member. Image forming apparatus.   When the intermediate transfer member moves from the attachment / detachment position to the image formation position, or moves from the image formation position to the attachment / detachment position, the intermediate transfer member slides on the contact surface of the intermediate transfer member by the rotational movement of the intermediate transfer member. The image forming apparatus according to claim 1, wherein the contact surface of the intermediate transfer member is scraped.

Images