JP2009069466A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress upsizing of an image forming apparatus with a simple structure, and also, to prevent a sheet conveying belt and an intermediate transfer belt from meandering and deviating with an easy operation, without deteriorating user's convenience. <P>SOLUTION: The circulating belt body 13 of an intermediate transfer belt or the like on which a developer image is transferred by a process cartridge, is prevented from being close to one side in a driving direction by engaging an abutting rib 13a disposed on the belt body 13 side with a grooved flange 15c having an annular groove disposed at the end part of a tension roller 15. Further, when the abutting rib 13a is separated from the grooved flange 15c to run on the tension roller 15, the rib 13a is effectively prevented from running on the tension roller 15 by pressing the rib 13a from above through the use of a roller member 91 (run-on preventing member). The belt is prevented from meandering and deviating without deteriorating user's convenience, and also, while minimizing the number of components. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus (hereinafter referred to as “image forming apparatus”) such as a copying machine, a printer, a facsimile machine, and a multifunctional multifunction machine, and transport using an endless belt provided in the image forming apparatus. The present invention relates to a belt or an intermediate transfer belt.

  In the case of an image forming apparatus using an electrophotographic process, particularly in the case of a color image forming apparatus, for example, Y (yellow), M (magenta), C (cyan), K on a recording material or a transfer material (hereinafter referred to as “sheet”). Each color toner image of (black) is transferred to obtain a color image. In the image forming unit, a latent image is formed for each color on the drum surface of the electrophotographic photosensitive drum as an image carrier. In a plurality of developing devices corresponding to each color, the latent image is referred to as a developer (hereinafter referred to as “toner”). ) To form a toner image. In this case, a method of obtaining a color image by directly transferring directly to a sheet conveyed by a conveyance belt is well known. Also known is a method in which a toner image is sequentially transferred to an intermediate transfer belt formed with an endless film material, and then the transferred toner images are collectively transferred onto a sheet to obtain a color image. ing.

  By the way, in both cases of the former sheet conveying belt and the latter intermediate transfer belt, an endless belt body is looped between a plurality of belt rollers including a driving roller and a driven roller, and is driven to circulate in the circumferential direction. Conventionally, the belt body that is being driven to drive meanders at a point that has been a problem, or may be driven to rotate around one side in the belt width direction. In order to prevent such deviation of the belt body, the present applicant has previously proposed a belt traveling device (see, for example, Patent Document 1).

  In the case of the belt traveling device disclosed in Patent Document 1, a protrusion (convex) -shaped abutting rib is provided on the inner peripheral side of the belt main body, and a concave groove with which the abutting rib engages is provided. A flange is provided on the rotation axis of the belt roller. A rib regulating member is provided on the outer peripheral side of the belt main body so as to regulate the deviation of the belt main body by the engagement of the concavo-convex portions and prevent the butting rib from riding on the grooved flange.

  On the other hand, in recent image forming apparatuses, a photosensitive drum as an image carrier and a developing device as a process means acting on the photosensitive drum are integrated into a cartridge so that it can be easily attached to and detached from the image forming apparatus. Process cartridges that can be used are often used.

JP 2004-45959 A

  The process cartridge is used over time and is taken in and out of the image forming apparatus for replacement of old and new. On the other hand, as described above, in the structure in which the abutting ribs and the regulating members for preventing the ribs are provided on the inner and outer peripheries of the belt main body to prevent the belt from being displaced, these abutting ribs etc. are obstructive when the process cartridge is replaced. It is necessary not to become.

  Therefore, the position where the abutment rib and the climbing prevention regulating member are provided on the belt body is regulated. That is, depending on the position where the regulating member is attached, there is a problem in that the positional accuracy with respect to the belt main body is lowered, and the abutting rib is easily dropped from the grooved flange. Further, when the process cartridge is taken out from the image forming apparatus, a structure is required in which the process cartridge is largely retracted to avoid interference with the belt body. For this reason, there is a problem that the operation by the user is complicated and the structure is complicated in order to restrict the position of the butting rib and the like and avoid interference, and the image forming apparatus is increased in size accordingly.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of effectively preventing meandering and shifting of a sheet conveying belt and an intermediate transfer belt without impairing the convenience of a user with a simple structure that can be prevented from increasing in size. Is to provide.

  In order to achieve the above object, a typical image forming apparatus according to the present invention includes an image carrier and a cartridge including a process unit acting on the image carrier, and an image formed by the cartridge is transferred to a recording material. An endless belt, a first engagement portion provided on the belt, and a first engagement portion that engages with the first engagement portion to regulate a belt shift in a direction perpendicular to the moving direction of the belt. In an image forming apparatus having two engaging portions and a restricting member for preventing the first engaging portion from being detached from the second engaging portion, the image forming apparatus is movable with respect to the apparatus main body, and the cartridge is It has a holding means for holding, and the regulating member is attached to the holding means.

  According to the image forming apparatus of the present invention, the first engagement portion is configured such that a belt main body such as an intermediate transfer belt to which a developed image is transferred by the cartridge is shifted to one side in the driving direction during circulation driving. And the second engagement part. Further, the first engaging portion is detached from the second engaging portion and tries to ride on the belt roller, but this is effectively prevented by pressing it from above with a regulating member. In addition, since the holding means for holding the cartridge ensures a high-precision positional relationship with the belt, providing a restriction member on the holding means guarantees high accuracy in the mounting position of the restriction member. Is done. Therefore, an effect that the first engaging portion can be reliably regulated by the highly accurate regulating member is obtained. Furthermore, with such a simple structure, the convenience of the user is not impaired, and the number of parts can be minimized, thereby preventing the belt from meandering and shifting.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of an image forming apparatus according to the invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a four-color full-color laser printer using an electrophotographic process as a specific example of the image forming apparatus of this embodiment. The apparatus main body 100 of the laser printer is used by being electrically and communicably connected to a host device which is an external device such as a personal computer, an image reading device, and a facsimile machine. The apparatus main body 100 receives operation signals based on various image information transmitted from the respective apparatuses, and transfers and records an image on a sheet P such as a transfer material that has been conveyed.

  Inside the apparatus main body 100, for example, four process cartridges PY, PM, PC, and PK corresponding to each color of Y (yellow), M (magenta), C (cyan), and K (black) are in tandem type with an in-line configuration. The structure is arranged horizontally. Each of these process cartridges provided with process means called “cartridge” in the present invention has the same structure except that the color of the toner to be accommodated is different.

  The process cartridge in this case incorporates an electrophotographic photosensitive drum (hereinafter simply referred to as “photosensitive drum”) 1 as a first image carrier. At least one of a charging device 2, a developing device 3 and a cleaning device 4 as process means acting on the photosensitive drum 1 is integrally incorporated in a cartridge frame 5 forming a cartridge frame to constitute a process cartridge. Yes. A contact-type charging roller is used for the charging device 2. The developing device 3 includes a developing roller 3a, and toner is accommodated in the developer container. As the cleaning device 4, a blade method for scraping and leveling toner can be applied.

  Therefore, the process cartridge PY stores Y toner in the developing device 3 and forms a Y toner image on the drum surface of the photosensitive drum 1. The process cartridge PM stores M-color toner in the developing device 3 and forms an M-color toner image on the drum surface of the photosensitive drum 1. The process cartridge PC stores C color toner in the developing device 3 and forms a C color toner image on the drum surface of the photosensitive drum 1. Then, the process cartridge PK stores K-color toner in the developing device 3 and forms a K-color toner image on the drum surface of the photosensitive drum.

  A laser scanner unit 11 is disposed above each process cartridge. The scanner unit 11 irradiates a laser beam L modulated in accordance with image information of each color output from a host computer or the like as an external device. The laser light L passes through an exposure through window 6 provided so as to penetrate the upper surface of the cartridge frame 5 of the process cartridge, and scans and exposes the drum surface of the photosensitive drum 1 inside the cartridge frame.

  In addition, as shown in FIG. 1, an intermediate transfer belt (endless-shaped belt) in which a flexible and dielectric film material or the like is formed endlessly as a second image carrier in the lower part of each process cartridge. A unit 12 mainly composed of a belt is disposed. The belt body 13 of the intermediate transfer belt unit 12 circulates between the belt rollers of the driving roller 14 and the driven roller 16 and the tension roller 15 that receive rotational power from the motor of the rotational driving source, and circulates in the circulation driving direction. The driving roller 14 and the driven roller 16 are disposed on the inner rear side of the apparatus main body 100. The tension roller 15 is disposed on the inner front side. The photosensitive drum 1 provided in each process cartridge has the lower surface of the drum surface in contact with the upper surface of the belt body 13. Four primary transfer rollers 17 are mounted on the inner peripheral side of the belt main body 13 at four positions at positions facing the respective photosensitive drums 1. The driving roller 14 is in contact with the secondary transfer roller 22 via the belt body 13.

  A sheet feeding unit 18 is disposed below the intermediate transfer belt unit 12. The paper feed unit 18 includes a paper feed tray 19, a paper feed roller 20, a separation pad 21, and the like. The paper feed tray 19 is detachable from the front side of the apparatus main body 100 (front loading type). Further, a fixing device 23 and a pair of paper discharge rollers 24 are arranged on the rear side of the apparatus main body 100 and a paper discharge tray 25 is arranged on the upper part of the apparatus main body 100. The fixing device 23 has a fixing film assembly 23a and a pressure roller 23b. The paper discharge roller pair 24 includes a paper discharge roller 24a and a paper discharge roller 24b.

  Each process cartridge is fixed and held in a pressed state by a pressing member 93 (see FIG. 3) described later at a fixed mounting position inside the apparatus main body 100. The drive input unit of each process cartridge is mechanically and electrically connected to the drive output unit provided on the apparatus main body 100 side, and the electrical contact provided on the process cartridge side drive input unit is connected to the power supply system on the apparatus main body 100 side. Thus, electrical conduction is achieved.

  With the above configuration, the image forming apparatus of the present embodiment operates as follows.

  When forming a full-color image, each photosensitive drum 1 provided in each of the process cartridges PY, PM, PC, and PK corresponding to Y, M, C, and K colors was controlled in the counterclockwise direction indicated by the arrow in FIG. Rotates at the set speed. The belt body 13 circulates at a traveling speed corresponding to the rotational speed of the photosensitive drum 1 in the clockwise direction indicated by the arrow (forward direction with respect to the drum rotation). Further, in each process cartridge in synchronism with the driving of the scanner unit 11, the charging device 2 applies a charging bias voltage uniformly to the drum surface of the photosensitive drum 1 with a predetermined polarity and potential at each control timing. Charged. Further, the scanner unit 11 scans and exposes the drum surface of each photosensitive drum 1 with a laser beam L that is modulated in accordance with image signals of Y, M, C, and K colors. In this way, an electrostatic latent image corresponding to the image signal is formed on the drum surface of each photosensitive drum 1 corresponding to Y, M, C, and K. The electrostatic latent image is developed with toner by the developing device 3 and visualized as a toner image.

  By the image formation using the electrophotographic process as described above, a Y toner image corresponding to the yellow component of the full color image is formed on the photosensitive drum 1 of the process cartridge PY, and the toner image is primarily transferred onto the belt body 13. Is done. Similarly, an M-color toner image corresponding to the magenta component of the full-color image is formed on the photosensitive drum 1 of the process cartridge PM, and the toner image is superimposed on the Y-color toner image already transferred on the belt body 13. Primary transfer. Also in the process cartridge PC, a C-color toner image corresponding to the cyan component of the full-color image is formed on the photosensitive drum 1, and the toner image has already been transferred onto the belt body 13. Is primarily transferred to the image. Finally, in the process cartridge PK, a K-color toner image corresponding to the black component of the full-color image is formed on the photosensitive drum 1, and the toner image is transferred onto the belt body 13 with the Y color + M color already transferred. Superimposed on the + C color toner image is primarily transferred. Thus, a four-color full-color unfixed toner image of Y color + M color + C color + K color is synthesized and formed on the belt body 13.

  Meanwhile, in each process cartridge, after the toner image is primarily transferred to the belt body 13, untransferred residual toner remaining on the drum surface of the photosensitive drum 1 is removed by the cleaning device 4.

  On the other hand, the sheet feeding roller 20 is driven to rotate at the control timing, and the sheet P stacked on the sheet feeding tray 19 is separated one by one in cooperation with the sheet feeding roller 20 and the separation pad 21. Be fed. The fed sheet P is fed to a secondary transfer nip portion between the secondary transfer roller 22 and the belt 13, and a four-color superimposed toner image on the belt main body 13 is transferred to one surface of the sheet P while being nipped and conveyed by the nip portion. Are collectively transferred in order.

  Subsequently, the sheet P is separated from the belt surface of the belt main body 13 and conveyed to the fixing device 23 where it is heated and pressurized at the fixing nip portion. As a result, the color mixture of each color toner image and permanent fixing to the sheet P are performed. After fixing, the sheet P is discharged onto the discharge tray 25 by the discharge roller pair 24 as a full-color image formed product.

  If the secondary transfer residual toner remains on the belt surface of the belt body 13 after the sheet P is separated, for example, the toner adheres electrostatically to the drum surface of the photosensitive drum 1 at the primary transfer portion of the process cartridge PY. It can be removed by the cleaning device 4.

  Next, FIG. 2 and FIG. 3 show a belt regulating mechanism which is a gist of the present embodiment and is provided in the intermediate transfer belt unit 12.

  The driving roller 14, the driven roller 16, and the tension roller 15 that wind the belt main body 13 are rotatably pivoted on the left and right belt holding frames 68R and 68L perpendicular to the sheet conveying direction via bearings 14a, 15a, and 16a. It is supported. When the driving roller 14 starts rotating upon receiving motor power, it rotates in the direction indicated by the arrow in FIG. The bearings 14a and 16a of the driving roller 14 and the driven roller 16 are positioned with high accuracy on the belt holding frames 68R and 68L on the left and right sides. The bearing 15a of the tension roller 15 is attached to the belt holding frames 68R and 68L so as to be slidable in the sheet conveying direction, that is, in a direction perpendicular to the roller rotation axis. The tension roller 15 together with the bearing 15a is urged by a tension spring 15b in a direction in which the belt body 13 is tensioned by tension.

  Therefore, at the one end side on the right side of the belt main body 13 in FIG. 2, an abutment rib (first engagement) for restricting the deviation of the belt toward one side, which is a direction orthogonal to the moving direction, on the endless inner circumferential surface. The joint portion 13a is formed in a convex shape in cross section, and constitutes a “belt regulating mechanism”.

  As is apparent from FIGS. 3A and 3B, a groove formed as an annular groove having a concave cross section at the end (one of the belt rollers) of the tension roller 15 at a position corresponding to the abutment rib 13a. A flange (second engagement portion) 15c is provided so as to be coaxial with the roller shaft. By engaging the abutment rib 13a provided protruding from the inner peripheral surface of the belt with the grooved flange 15c coupled to the end of the tension roller, the belt body 13 is restricted from moving to one side. Yes.

  Incidentally, although the belt body 13 is offset slightly, the accuracy of the distance between the roller shafts is very slight, the dimensional difference due to the difference in the circumferential length between the left and right ends of the belt, and the change in the belt thickness dimension. This is due to the occurrence of offset force depending on accuracy. There is also a problem of the next climb resulting from the deviation. That is, even when the abutting rib 13a protruding from the belt body 13 regulates the belt one side, the abutting rib 13a is shifted to the left or right unspecified direction by the grooved flange 15c. There is. When the shifting force is increased, the abutting rib 13a is detached from the grooved flange 15c and rides on the tension roller 15.

  As shown in FIGS. 3A and 3B, the abutment rib 13 a is a gist member of the present embodiment that forms a “belt regulating mechanism” together with the abutment rib 13 a, and the abutment rib 13 a rides on the tension roller 15. A roller member (regulating member) 91 is provided to prevent this.

  That is, the roller member 91 is rotated around the rotation axis of the tension roller 15 on the outer periphery of the belt body 13 near the upstream side where the abutment rib 13a is engaged with the grooved flange 15c and moves. It is provided parallel to the axis. The roller member 91 is rotatably supported by a roller bearing 92 and serves to suppress the swelling of the belt body 13, and is disposed on the upper portion of the intermediate transfer belt unit 13. The roller bearing 92 is used as a means for moving the process cartridge to the outside of the apparatus main body 100 at the time of replacement, and in the vertical direction on the right front part of the cartridge attaching / detaching holding tray (holding means) 35 shown in each figure of FIG. A slide is attached to be possible. The cartridge attaching / detaching holding tray 35 serves as a moving body in the attaching / detaching direction, which is also referred to as a guide portion or a guide member provided on the apparatus main body 100 side, in order to hold and attach the process cartridge when replacing the process cartridge. To do.

  Here, the cartridge attachment / detachment holding tray 35 will be described. As shown in FIG. 4, the cartridge attachment / detachment holding tray 35 has an outer frame portion formed of front and rear frames 35a and 35c and left and right frames 35d and 35e formed in a frame shape. In the illustrated example, the inside of the outer frame portion is divided into four substantially in the front-rear direction in the sheet conveying direction by three parallel partition plates 35f. That is, the first to fourth horizontally long small frame portions 35 (1) to 35 (4) are formed from the rear frame 35c to the front frame 35b of the outer frame portion 35d. Four process cartridge cartridges PY, PM, PC, and PK corresponding to Y, M, C, and K colors are held in each of the small frame portions 35 (1) to 35 (4).

  Further, the roller bearing 92 is provided on the front side of the tray on the right side of FIG. 4, and a pressing member 93 is attached to the front side of the left side so as to be slidable in the vertical direction of FIG. As apparent from FIG. 5, the roller bearing 92 is pressed and urged downward by a biasing member 92 b formed by a spring or the like provided on the cartridge mounting / removal holding tray 35. The abutting surface 92a of the roller bearing 92 is abutted against the right belt retaining frame 68R in a state where the cartridge mounting / removal retaining tray 35 is positioned at the position when the latent image is formed. The roller bearing 92 maintains a constant distance between the belt surface of the belt body 13 and the outer shape of the roller member 91. At the same time, the roller bearing 92 presses the belt holding frames 68R and 68L downward and holds the right belt holding frame 68R in the positioning portion of the inner stay provided in the apparatus main body 100. Similarly to the roller bearing 92, the pressing member 93 is pressed downward by a biasing member 93a by a spring or the like provided on the cartridge attaching / detaching holding tray 35, and when the image forming operation is performed, that is, the latent image is formed. Is abutted against the left belt holding frame 68L. Accordingly, the left belt holding frame 68L is pressed downward, and the belt holding frame 68L is held by the stay member of the inner plate.

  The Y, M, C, and K process cartridges are inserted from above into booth portions 35 (1) to 35 (4) that partition the inside of the cartridge mounting / removal holding tray 35. Each process cartridge is held in such a manner that the lower surfaces of the left and right flanges 56 (see FIG. 12) are received by the upper surfaces of the left and right frames 35d and 35e of the cartridge mounting / removal holding tray 35. That is, the cartridge mounting / removal holding tray 35 holds each process cartridge so that it can be taken out right above, and holds each process cartridge by moving it downward. The cartridge mounting / removal holding tray 35 holds each process cartridge in a rough state so as not to be cramped. This facilitates attachment / detachment workability when replacing each process cartridge.

  As shown in FIG. 6, the left and right frames 35d and 35e of the cartridge attaching / detaching holding tray 35 are fitted into and engaged with guide groove portions 34a formed in the front and rear directions on the inner side surfaces of the left and right tray holding frames 34L and 34R, respectively. ing. As a result, the cartridge mounting / removal holding tray 35 is supported between the left and right tray holding frames 34L and 34R, is slid by being guided by the guide groove 34a, and is horizontal in the front-rear direction with respect to the tray holding frames 34L and 34R. Slide movement is possible. FIG. 5 shows the engagement between the roller member 91 of the cartridge attaching / detaching holding tray 35 and its roller bearing 92. The cartridge attaching / detaching holding tray 35 is provided with a guide portion 35h, and the guide portion 35h is fitted into and engaged with a groove 92c provided in the roller bearing 92, whereby the roller bearing 92 is moved in the front-rear and left-right directions. And allows sliding only in the vertical direction.

  3 (a) and 3 (b), the roller member 91 of the cartridge attaching / detaching holding tray 35, the roller bearing 92, and the grooved flange 15c provided to be coupled to the end of the tension roller 15 are shown in FIG. It is shown from the front side of the main body 100. As shown in FIG. 3A, the abutting portion 91a of the roller support member 91 is in contact with the belt holding frames 68R and 68L of the intermediate transfer belt unit 12 during image formation. It is pressed by the biasing means 92b of the bearing 92. In this state, the distance l from the outer peripheral surface of the belt body 13 to the outer shape of the roller member 91 is set to be equal to or less than the thickness t of the rib 13b. Further, as shown in FIG. 3B, the pressing force Pk by which the biasing means 92 b presses and biases the roller bearing 92 causes the abutment rib 13 a to come out from the grooved flange 15 c of the tension roller 15 and ride on. It is larger than the force Pr. Therefore, even if a strong shifting force is generated in the belt main body 13, the abutment rib 13a does not come out of the grooved flange 15c, and the belt main body 13 can be protected from damage.

  In addition, in this embodiment, although the structure which provided the butting rib 13a which prevents that assuming that the belt main body 13 shifted | deviated to one side was shown, it is an example to the last. It is of course possible to provide such abutment ribs 13a on both sides of the belt, which is determined cost-effectively. When provided on both sides of the belt, only the roller member 91 and its roller bearing 92 need be provided instead of the pressing member 93 shown in FIG.

(When replacing process cartridge)
In each of the Y, M, C, and K process cartridges, the toner accommodated in the developing device 3 is consumed with the passage of time by image formation. When the toner is consumed to such an extent that it is difficult for a user who purchases a process cartridge to form a high-quality image, the commercial value of the cartridge is lost.

  Therefore, in that case, a means for detecting the remaining amount of toner in each process cartridge is provided, and various types of toner consumption are controlled by a control means such as a CPU (Central Processing Control Unit) based on a detection signal from the remaining toner amount detecting means. Control can be executed. For example, a detection value obtained by detecting the remaining amount of toner by a toner sensor is monitored by comparing with a threshold value as a design upper limit value. When the detection value of the remaining amount of toner exceeds a threshold value, a cartridge life warning or a life warning is transmitted to the user for recognition. Further, for a process cartridge in which the detected value of the remaining amount of toner is below the threshold value, a notice or a life warning indicating that the process cartridge has reached the end of its life is displayed on the display unit. The display prompts the user to prepare for the replacement of the process cartridge. Alternatively, the replacement of the process cartridge is urged to maintain the quality of the output image.

  As can be understood from the above description, in the image forming apparatus according to the present embodiment, the replacement of the process cartridge with the new one improves the convenience for the user. For this purpose, a cartridge mounting / removal holding tray 35 for pulling out the process cartridge from the apparatus main body 100 and taking it out is mounted as a carriage so that the replacement work can be performed from the front of the apparatus main body 100. As shown in FIGS. 1 and 7 and subsequent drawings, a cartridge for inserting and mounting a process cartridge in the apparatus main body 100 on the front side of the image forming apparatus, and a cartridge for pulling out and removing the process cartridge from the apparatus main body 100 A mounting opening 30 is provided.

  An opening door 31 is provided that moves in the opening and closing direction between a closed position and an open position of the cartridge mounting opening 30. The opening door 31 rotates in the opening / closing direction with respect to the apparatus main body 100 with the door hinge 32 shown in FIG. Further, the opening door 31 is pivoted up and down from the door hinge 32 so that the apparatus main body 100 is closed as shown in FIG. When the door hinge 32 is tilted toward the front side of the apparatus main body 100, the process cartridge can be taken out from the apparatus main body 100 as shown in FIG. Thereby, the cartridge mounting opening 30 is largely opened on the front side of the apparatus main body 100. The opening / closing operation of the door 31 is performed by hooking the finger hanging portion 31a.

  Further, as shown in FIG. 13, it has a main frame 81 that forms a skeleton of the apparatus main body 100. A pair of left and right tray holding frames 34L, 34R (moving means) 34L, 34R having a longitudinal direction in the front-rear direction are arranged such that the inner side of the left frame 81L faces the inner surface of the right frame 81R. A cartridge attaching / detaching holding tray 35 is held between the tray holding frames 34L and 34R so as to be slidable horizontally in the front-rear direction. The Y, M, C, and K process cartridges are held on the tray 35.

  In conjunction with the opening of the opening door 31, the tray holding frames 34L and 34R move by an amount (distance) set in the forward direction and the upward direction, as will be described later. By the movement, the tray holding frames 34L and 34R are pulled out to the positions where the front side portions protrude from the cartridge mounting opening 30 to the outside of the apparatus main body 100 by a set length as shown in FIG.

  In conjunction with the movement of the tray holding frames 34L and 34R, the following mechanical and electrical connection ON / OFF operations are performed on the apparatus main body 100 in each process cartridge. When the process cartridges are attached and detached, the drive input units are mechanically and electrically connected to ON / OFF to the drive output unit on the apparatus main body 100 side. Further, the pressing force of the pressing member for positioning and fixing each process cartridge is turned ON / OFF when the process cartridges are attached and detached. In addition, when the process cartridges are attached and detached, their electrical contacts are turned on / off to the power supply system on the apparatus main body 100 side to enter a power supply state or a power supply release state. Further, with the movement of the tray holding frames 34L and 34R, the positioning of the tray 35 that has been fixed so far is also released.

  In this state, the cartridge attaching / detaching holding tray 35, which is seen from the cartridge mounting opening 30 to the outside, is put on the handle portion 35a with a finger to open the drawer. The cartridge mounting / removal holding tray 35 is slid with respect to the tray holding frames 34L and 34R, pulled out horizontally, and pulled out to the state shown in FIG. The Y, M, C, and K color process cartridges PY, PM, PC, and PK held on the drawn cartridge attaching / detaching holding tray 35 are all pulled out from the cartridge mounting opening 30 to cover the upper surface of the cartridge. Open. The cartridge mounting / removal holding tray 35 that has been sufficiently ejected by the necessary amount is prevented from being further pulled out by a stopper (not shown). In such a pulled-out state, the cartridge attaching / detaching holding tray 35 is stably held by the tray holding frames 34L, 34R.

  In the cartridge mounting / removal holding tray 35, each process cartridge can be taken out right above, and each process cartridge is held so that it can be moved right below. Therefore, the used process cartridge to be replaced is lifted and removed from the cartridge mounting / removal holding tray 35 as shown by a two-dot chain line in FIG. Then, a new process cartridge is fitted into the cartridge attaching / detaching holding tray 35 from above.

  In that case, in a type of process cartridge having an openable drum cover (not shown) that protects the lower surface of the photosensitive drum 1, the cover is manually closed after being removed from the cartridge mounting / removal holding tray 35. Further, before the new process cartridge is placed on the cartridge mounting / removal holding tray 35, the cover is manually opened. Alternatively, the cover automatically closes in the process of lifting the process cartridge upward from the cartridge attaching / detaching holding tray 35 and removing it. On the contrary, the cover automatically opens in the process of being fitted onto the cartridge mounting / removal holding tray 35 from above.

  As can be seen from the above, the cartridge mounting / removal holding tray 35 is a moving body that moves along the conveyance direction of the sheet P. The cartridge mounting / removal holding tray 35 can carry the process cartridge from the cartridge mounting opening 30 to first to third positions which are two positions. The first position is between a drawing start position where the process cartridge can be taken out of the apparatus main body 100 and an insertion start position where the process cartridge can be attached to the inside of the apparatus main body 100 from the outside. The second position is a latent image forming position where an electrostatic latent image can be formed on the photosensitive drum 1 during image formation.

  That is, at the first position, before the cartridge mounting / removal holding tray 35 is moved to the drawing start position, it is moved upward from the insertion start position and is moved downward toward the insertion start position. In other words, the tray holding frames 34L and 34R are support members that movably support the cartridge attaching / detaching holding tray 35, and at the same time, a movable body that can position the cartridge attaching / detaching holding tray 35 at the first position and the second position. But there is. That is, in conjunction with the closing operation of the opening door 31, the tray holding frames 34L and 34R are retracted from the first position to the second position.

  The cartridge attaching / detaching holding tray 35 is pulled out to the position shown in FIG. 8, and the replacement of the old and new ones of the process cartridges held on the cartridge attaching / detaching holding tray 35 is completed. After the replacement, the cartridge mounting / removal holding tray 35 is sufficiently pushed in and moved to be housed in the apparatus main body 100 and brought into the state before drawing shown in FIG. 7, and then the opening door 31 is closed to return to the state shown in FIG. .

  In conjunction with the closing operation of the opening door 31, the tray holding frames 34L and 34R move by a set amount determined in the rearward and downward directions, whereby each process cartridge is moved to the mounting position and positioned. That is, in conjunction with the movement of the tray holding frames 34L and 34R, each process cartridge is pressed by a pressing member and held in a fixed state at a predetermined positioning portion, and the lower surface of the photosensitive drum 1 in each process cartridge is held. Contact is made at a predetermined position of the belt main body 13. In this way, the drive input portion of the process cartridge cartridge is mechanically and electrically connected to the drive output portion on the apparatus main body 100 side, and is connected to be electrically connected in a conductive state.

(Door and tray holding frame interlocking mechanism)
Here, an interlocking mechanism between the opening door 31 and the tray holding frames 34L and 34R is shown with reference to FIG. The door hinge 32 of the opening door 31 extends horizontally in the left-right direction of the apparatus main body 100. The left and right ends of the shaft are supported between the left and right frames 80L and 80R (see FIG. 13) constituting the main frame of the apparatus main body 100 so as to be rotatable. The opening door 31 is integrally coupled to the door hinge 32. The door hinge 32 rotates together with the opening / closing movement of the opening door 31. Further, connecting arms 37L and 37R are integrally coupled at the same phase near the left and right ends of the door hinge 32, respectively. A lateral shaft pin 37a is coupled to each of the left and right connecting arms 37L and 37R, and the lateral shaft pin 37a of the left connecting arm 37L is fitted into a vertically elongated hole 34b provided in the lower front portion of the left tray holding frame 34L. is doing. Further, the lateral shaft pin 37a of the right connecting arm 37R is fitted in a vertically long hole 34b provided in the lower front portion of the right tray holding frame 34R.

  As shown in FIGS. 9A to 9C, the door hinge 32 and the tray holding frames 34L and 34R are connected via connecting arms 37L and 37R, a lateral shaft pin 37a, and a vertically long hole 34b. . Accordingly, when the opening door 31 is opened and closed, a moving force in the front-rear direction acts on the left and right tray holding frames 34L and 34R. In the tray holding frames 34L and 34R, two pin shafts 34c which are raised and fixed at intervals in the front and rear directions are engaged with guide holes 36 provided in the left and right frames 80L and 80R constituting the main frame of the apparatus main body 100, respectively. I am letting. The tray holding frames 34L and 34R are supported by the left and right frames 80L and 80R, respectively, by the engagement of the pin shaft 34c and the guide hole 6 by the unevenness.

  The right tray holding frame 34R has the same shape as the left tray holding frame 34L, and the pin shaft 34c and the guide hole 36 are formed symmetrically with the left tray holding frame 34L. Therefore, the left and right tray holding frames 34L and 34R have a degree of freedom to move relative to the left and right frames 80L and 80R in the guide range by the guide holes 36, respectively.

  FIG. 10 is an enlarged view of the guide hole 36. Each of the guide holes 36 includes a first guide region 36a that is horizontal in the front-rear direction and a second guide region 36b that is inclined upward and is provided continuously in the pin shaft forward direction of the first guide region 36a. Moreover, it has the 3rd guide area | region 36c which receives and stably hold | maintains the pin axis | shaft 34c provided in a row at the top of the 2nd guide area | region 36b. The pin shaft 34c, that is, the left and right tray holding frames 34L and 34R is moved by the distance a1 in the horizontal direction by the first guide region 36a in conjunction with the opening operation of the door 31, and then obliquely upward (in the horizontal direction by the second guide region 36b. Move to distance a2 and distance b) in the vertical direction. Finally, the third guide region 36c moves by a distance a3 in the horizontal direction.

  Again, FIG. 9A shows a state in which the opening door 31 is completely closed by the apparatus main body 100. At this time, the left and right tray holding frames 34L and 34R are moved to the inner rear side of the apparatus main body 100 via the hinge shaft 32, the left and right connecting arms 37L and 37R, the lateral shaft pin 37a, and the vertically long hole 34b. The pin shaft 34 c is located at the rear end portion of the first guide region 36 a of the guide hole 36. Therefore, the left and right tray holding frames 34L and 34R are held at predetermined lowered positions (second positions) with respect to the left and right left frames 80L and 80R, respectively. Therefore, the cartridge attaching / detaching holding tray 35 held by the tray holding frames 34L, 34R is also held at a predetermined lowered position (second position: latent image forming position).

  Each process cartridge PY, PM, PC, PK held on the cartridge mounting / removal holding tray 35 is pressed by the pressing member 93 (see FIG. 1) at the upper left and right sides. As a result, as shown in FIG. 12, the lower surface portions (positioned portions) of the driving-side bearing portion 51 and the non-driving-side bearing portion 52 are positioned on the positioning portion provided on the stay member (inner plate) of the apparatus main body 100. Fixed. Each process cartridge is positioned and held at a predetermined position by the apparatus main body 100. In this state, the lower surface of the photosensitive drum 1 in each process cartridge is in contact with the upper surface of the upper belt portion of the intermediate transfer belt unit 12 in a predetermined and stable manner. In addition, the drum driving coupling and the developing driving coupling on the apparatus main body 100 side are fitted in the coupling fitting portions 53 and 54 of each process cartridge, respectively.

  Further, as shown in FIG. 11, the cartridge mounting / removal holding tray 35 is positioned at the lower end portion of the downward projecting portion 67 through a hole 69L provided in a belt holding member 68L which is a stationary member on the apparatus main body side. At this time, the abutting portion 92a of the roller bearing 92 abuts against the left belt holding frame 68L and is pressed downward with a predetermined force by the urging means 92b.

  Therefore, the distance between the roller member 91 supported by the roller bearing 92 and the belt body 13 is determined by the position of the left belt holding frame 68L, regardless of the position of the cartridge mounting / removal holding tray 35. For this reason, even if the vertical position of the cartridge mounting / removal holding tray 35 varies due to component accuracy or environmental fluctuation, the distance between the outer shape of the roller member 91 and the outer peripheral surface of the belt body 13 can be maintained with high accuracy. . The above effects are described as the effects of the present invention. “Since the holding means for holding the cartridge has a highly accurate positional relationship with the belt, a restriction member is provided on the holding means. The accuracy of the mounting position of the restricting member is also ensured to be high, so that the effect that the first engaging portion can be reliably restricted by the highly accurate restricting member is obtained.

  When the opening door 31 is opened from the state where the opening door 31 shown in FIG. 9B is partially opened to the door closing state shown in FIG. 9A, the left and right tray holding frames are interlocked. 34L and 34R are pulled forward in the apparatus main body. As a result, in FIG. 10, the tray shafts 34L and 34R are first guided by the first guide region 36a of the guide hole 36 in the pin shaft 34c and first moved in the horizontal direction forward by the distance a1 [FIG. 9 (b). ]. In the process of moving the tray holding frames 34L and 34R by the distance a1, the drum drive coupling and the development drive coupling for each process cartridge are released. Further, the positioning of each process cartridge by the pressing member 93 is also released. At this time, the lower end portion of the downward projecting portion 67 provided on the tray is inserted into the hole 69 provided on the stationary member 68L on the apparatus main body side so that the cartridge attaching / detaching holding tray 35 does not follow the movement of the tray holding frames 34L and 34R. Engaged and positioned.

  In conjunction with the opening operation of the opening door 31, the tray holding frames 34L and 34R are further pulled forward in the apparatus main body 100. Accordingly, the tray holding frames 34L and 34R move obliquely upward as the pin shaft 34c is guided by the second guide region 36b of the guide hole 36. In the process of moving the tray holding frames 34L and 34R obliquely upward, the electrical connection between the electrical contact 55 of each cartridge and the apparatus main body is released.

  Here, FIG. 11 shows the amount of the protrusion 67 entering the hole 69 as c, and the amount of ascending as the tray holding frames 34L and 34R holding the cartridge attaching / detaching holding tray 35 are moved upward as b. . When the tray holding frames 34L and 34R move obliquely upward, while the protrusions 67 of the cartridge mounting / removal holding tray 35 are engaged with the holes 69 (c> b), the protrusions 67 are connected to the tray holding frames 34L and 34L. Follow only the vertical movement of 34R. Then, in a state where the tray holding frames 34L and 34R are lifted to some extent (c ≦ b), the protruding portion 67 comes out of the hole 69. With such a configuration, the cartridge attaching / detaching holding tray 35 is horizontal when the drum lower surface of each cartridge PY / PM / PC / PK held by the cartridge attaching / detaching holding tray 35 is in contact with the belt body 13. Never move in the direction. Therefore, damage caused by rubbing between the photosensitive drum 1 and the belt main body 13 and generation of memory can be prevented.

  Further, as shown in FIG. 3A, when the roller bearing 92 moves downward by a distance d from the state of FIG. 9A, the claw portion 92d provided on the roller bearing 92 causes the cartridge mounting / removal holding tray 35 to move. It stops so as to hit against the roller bearing restricting portion 35h provided on the surface. For this reason, when the tray holding frames 34L and 34R are lifted to some extent (d ≦ b), the abutting portion 92a of the roller bearing 92 is separated from the belt holding frames 68R and 68L. Therefore, the roller bearing 92 can be easily moved in the horizontal direction together with the cartridge attaching / detaching holding tray 35 without sliding with the belt holding frames 68R and 68L.

  FIG. 9C shows a state in which the opening door 31 is fully opened. In this state, the tray holding frames 34L and 34R finish the oblique upward movement by the second guide region 36b, and the pin shaft 34c is positioned in the horizontal third guide region 36c. That is, the tray holding frames 34L and 34R move in the horizontal direction after moving obliquely upward. This is to stabilize the position of the process cartridge and the tray holding frames 34L and 34R in the height direction when the cartridge holding tray 35 is subsequently pulled out from the tray holding frames 34L and 34R and the cartridge is replaced. In addition, the tray holding frames 34L and 34R are prevented from moving back to their original positions.

  In the state shown in FIG. 9C, the protrusion 67 is removed from the hole 69L, and the positioning state of the cartridge mounting / removal holding tray 35 is released. Further, the abutting surface 92a of the roller bearing 92 is in a state of being separated from the belt holding frames 68R and 68L. Therefore, the cartridge attaching / detaching holding tray 35 can be freely slid horizontally in the front-rear direction with respect to the tray holding frames 34L, 34R.

  The protrusion 67 and the hole 69L restrict the cartridge mounting / removal holding tray 35, which is a moving body, from moving in a direction intersecting the direction in which the photosensitive drum 1 and the belt main body 13 contact each other at the mounting position in the apparatus main body. It is a movement control means. The movement restriction of the cartridge attaching / detaching holding tray 35 by the movement restricting means 67, 69L follows the movement of the direction component in which the photosensitive drum 1 and the belt main body 13 are in contact with the left and right tray holding frames 34L, 34R as the moving means. As a result, the cartridge attachment / detachment holding tray 35 follows and is released.

  The left and right tray holding frames 34L and 34R, which are moving bodies, are guided by the first guide region 36a and move in a direction intersecting the direction in which the photosensitive drum 1 and the belt main body 13 contact each other (first movement). The tray holding frames 34L and 34R are then guided to the first guide region 36a and have two directional components: a direction in which the photosensitive drum 1 and the belt main body 13 are in contact with each other, and a direction that intersects with the direction in which the contact is made. Move in an oblique direction (second movement). Thereafter, the tray holding frames 34L and 34R move in a direction intersecting with the direction in which the photosensitive drum 1 and the belt main body 13 contact each other (third movement). The tray holding frames 34L and 34R turn off the driving of the process cartridge in the first movement. Then, following the movement of the direction component in which the photosensitive drum 1 and the belt main body 13 contact each other, the movement restricting means 67 and 69L are released after the cartridge attaching / detaching holding tray 35 follows. Accordingly, the roller member 91 and the roller bearing 92 that prevent the butting rib 13a provided on the inner surface of the belt main body 13 from climbing away from the position that prevents the rib from abutting against the belt holding frames 68R and 68L. That is, when the cartridge is replaced, it moves together with the cartridge attaching / detaching holding tray 35 to a separation position where it can move out of the apparatus main body.

  As described above, the member that prevents the butting rib 13a provided on the belt main body 13 from climbing is retracted from the vicinity of the belt in accordance with the process cartridge replacement operation. Accordingly, even when a member for preventing the ride-up is arranged on the cartridge take-out path, it is not necessary to take out the cartridge while avoiding the ride-up preventing member. Therefore, the image forming apparatus main body can be downsized. Further, since the ride-up prevention member can be moved in accordance with the cartridge exchange operation that is normally performed, the cartridge exchange operation is complicated by the movement of the ride-up prevention member, and the convenience to the user is not impaired.

1 is a diagram illustrating a laser printer that is an embodiment of an image forming apparatus according to the present invention. FIG. FIG. 5 is a view showing the relationship between the intermediate transfer belt unit and the belt deviation regulating mechanism according to the present embodiment. (A), (b) is a diagram showing a belt deviation regulating mechanism for preventing the belt deviation regulating rib from being climbed by a rib running preventing member. The figure which shows the holding tray for cartridge attachment / detachment. The figure which expands and shows a belt deviation | shift regulation mechanism. The figure which shows the interlocking | linkage mechanism of an opening door and a tray holding frame. The figure which shows the laser printer of the state which opened the opening door. The figure which shows the state which pulled out the holding tray for cartridge attachment / detachment from the state of FIG. (A)-(c) is a figure explaining the movement of the tray holding member interlock | cooperated with opening rotation of a door. The figure which expands and shows a guide hole part. The figure which expands and shows the projection part and hole part as a tray movement control means. The figure which shows the external appearance of a process cartridge. The figure explaining a tray position control means.

Explanation of symbols

100 Image forming apparatus main body PY / PM / PC / PK Process cartridge 12 Intermediate transfer belt unit 13 Belt main body 13a Abutting rib (first engaging portion)
14 Driving roller 15 Tension roller 15a Grooved flange (second engaging portion)
16 driven roller 34L, 34R tray holding frame 35 cartridge holding tray 68L, 68R belt holding frame 91 roller member (regulating member)
92 Roller bearing

Claims (4)

A cartridge having an image carrier and process means acting on the image carrier, an endless belt for transferring an image formed by the cartridge to a recording material, and a first engagement provided on the belt A second engaging portion that engages with the first engaging portion to regulate a shift of the belt in a direction orthogonal to the moving direction of the belt, and the first engaging portion is the second engaging portion. An image forming apparatus having a restricting member for preventing separation from
An image forming apparatus comprising: holding means that is movable with respect to the apparatus main body and holds the cartridge; and the restricting member is attached to the holding means. When the first engaging portion is an abutting rib formed in a convex cross section and the second engaging portion is an annular groove formed in a concave cross section,
The restricting member that presses against the abutment rib that is guided by engaging with the annular groove from above and suppresses the ride is a roller member that is rotatably supported by a holding unit that holds the cartridge. The image forming apparatus according to claim 1.   The roller member is retracted to a first position where the abutment rib is pressed from above during image forming operation to prevent the roller member from climbing and to a position where it does not interfere when the roller member is pulled out from the image forming apparatus main body when the cartridge is replaced. The image forming apparatus according to claim 2, wherein the image forming apparatus is movable between a second position and a second position separated from each other.     A biasing member that presses and biases the roller member pivotally supported by the holding means toward the first position, and the roller member moves backward to the second position against the biasing member; The image forming apparatus according to claim 3.