JP5782946B2 - Image forming apparatus and intermediate transfer assembly - Google Patents

Description

  The present invention relates to an image forming apparatus and an intermediate transfer assembly.

  2. Description of the Related Art Image forming apparatuses including an intermediate transfer belt that receives transfer of toner images from a plurality of image holding members that hold toner images and performs secondary transfer onto a recording medium are widely used. In this type of image forming apparatus, an image carrier that holds a toner image using black (K) toner is always in contact with the intermediate transfer belt. In contrast, an image carrier that holds a toner image using a color toner other than black (K) is brought into contact with an intermediate transfer belt in a color mode for forming a color image, and in an monochrome mode for forming a monochrome image. A configuration in which they are separated from each other is employed (Patent Documents 1 and 2).

  Japanese Patent Application Laid-Open No. H10-228561 discloses that the impact when switching from the monochrome mode to the color mode is suppressed.

JP 2000-371404 A Japanese Patent Laying-Open No. 2005-156776 JP 2009-0775350 A

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus capable of suppressing the impact sound when switching from the monochrome mode to the color mode and shortening the time until the start of image formation after switching to the color mode.

Claim 1
A plurality of image holders for receiving toner image formation while rotating and holding the toner image;
A toner image that passes through a moving path along the plurality of image carriers and circulates in contact with at least some of the plurality of image carriers and receives the transfer of the toner image held by the image carrier, and receives the toner image Is disposed at a position where the moving path is sandwiched between an intermediate transfer belt for secondary transfer of the toner to a recording medium and an image carrier, and the intermediate transfer belt passing through the moving path is pressed and retracted by pressing, A pressing member for bringing the intermediate transfer belt into contact with a portion of the plurality of image holding members to which the intermediate transfer belt comes in contact with and separating, and the pressing member in a direction for pressing the intermediate transfer belt against the pressing member. The pressing member is resisted against the urging force of the first urging member by being slidable in the direction along the first urging member and the plurality of image holding bodies and sliding in the first direction. In the opposite direction to the first direction A slide member that causes the pressing member to press the intermediate transfer belt by sliding in the second direction, a cam shaft that extends and rotates in a width direction that intersects the circulating movement direction of the intermediate transfer belt, and a slide member that is fixed to the cam shaft A cam member that slides the slide member according to the rotation of the cam shaft by interfering with the cam shaft, a braking member that receives the sliding of the cam shaft and brakes the rotation of the cam shaft, and biases the braking member to release the braking member An intermediate transfer assembly having a second urging member that controls the strength of braking by the toner, and a fixing device that fixes the toner image on the recording medium that has received the secondary transfer of the toner image from the intermediate transfer belt. An image forming apparatus characterized by the above.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the second urging member is a tension spring, and the intermediate transfer assembly is in a state after the slide member is slid in the first direction. The second urging member has a structure that extends when slid in the second direction.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the intermediate transfer assembly includes a pair of slide members disposed at positions separated from each other in the width direction, and each of the pair of slide members is disposed. And a pair of cam members that are fixed to the cam shaft at each position and simultaneously slide the pair of slide members in the first direction and the second direction, respectively, and one braking member is provided on the cam shaft. It is characterized by being attached only.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the intermediate transfer assembly is disposed at a position sandwiching the pair of slide members from both sides in the width direction so as to rotatably support both ends of the cam shaft. The brake member and the second urging member are arranged on the outer side in the width direction of one of the pair of support members.

According to a fifth aspect of the present invention, the toner image is formed while rotating and passes through a moving path along the plurality of image holding bodies for holding the toner image, and is in contact with at least a part of the plurality of image holding bodies. An intermediate transfer belt that circulates and receives the transfer of the toner image held by the image carrier, and secondarily transfers the toner image to a recording medium;
The intermediate transfer belt of the plurality of image carriers is disposed at a position sandwiching the movement path between the image carrier and the intermediate transfer belt passing through the movement path so as to press and retract freely. A pressing member that causes the intermediate transfer belt to contact a part of the image carrier that contacts and separates; a first biasing member that biases the pressing member in a direction in which the pressing member presses the intermediate transfer belt; The pressing member is retracted against the urging force of the first urging member by sliding in the first direction and sliding in the first direction, and is opposite to the first direction. The slide member is fixed to the cam shaft, a slide member that presses the intermediate transfer belt against the pressing member by a slide in the second direction, a cam shaft that extends and rotates in a width direction that intersects the circulating movement direction of the intermediate transfer belt, and Interference with the slide member A cam member that slides the slide member in response to the rotation, a braking member that brakes the rotation of the cam shaft in response to sliding of the cam shaft, and biasing the braking member to control the strength of braking by the braking member And a second biasing member.

  According to the image forming apparatus of the first aspect and the intermediate transfer assembly of the fifth aspect, compared with the case where the present configuration is not provided, the impact sound can be reduced and the time until the start of image formation after switching to the color mode can be reduced. It is done.

  According to the image forming apparatus of the second aspect, the switching time from the monochrome mode to the color mode is further shortened as compared with the case where this configuration is not provided.

  According to the image forming apparatus of the third aspect, the cost can be reduced.

  According to the image forming apparatus of the fourth aspect, it is possible to suppress adverse effects caused by the foreign matter generated by the braking member.

1 is a schematic configuration diagram of a copying machine as an example of an image forming apparatus. FIG. 4 is a schematic diagram of an intermediate transfer belt switching mechanism showing a relationship between a photoconductor and an intermediate transfer belt in a color mode. FIG. 4 is a schematic diagram of an intermediate transfer belt switching mechanism showing a relationship between a photoreceptor and an intermediate transfer belt in a monochrome mode. It is the top view which showed the slider and the rotation cam. It is the side view which showed the slider and the rotation cam. It is the figure which showed the 2nd example of the attachment method of the spring which determines the braking force of a brake.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic configuration diagram of a copying machine as an example of an image forming apparatus.

  The copier 100 includes a scanner 101 and a printer 102. The scanner 101 is an apparatus that reads an image from a document and generates image data. The scanner 101 is not different from the conventional scanner, and detailed description thereof is omitted.

  Image data generated by the scanner 101 is input to the control unit 10 of the printer 102. In the control unit 10, image data input from the scanner 101 is converted into image data for exposure light modulation in an exposure unit 26 described later.

  The printer 102 is provided with a paper discharge tray 11 on the top thereof for discharging the paper after the image is formed. A sheet feed stand 12 is disposed below the printer 102. The paper feed tray 12 accommodates sheets P before image formation in a stacked state. The paper feed tray 12 is configured to be freely drawn out for replenishing the paper P.

  The paper P is fed from the paper feed tray 12 by the pickup roll 13 and separated one by one by the separation roll 14, and the single paper P is moved upward in the direction of arrow A on the transport path 151 by the transport roll 15. Then, the waiting roll 16 adjusts the timing of the subsequent conveyance, and further conveys it upward. The conveyance of the sheet after the standby roll 16 will be described later.

  Four image forming engines 20Y, 20M, 20C, and 20K are arranged substantially at the center of the printer 102 in the vertical direction. These image forming engines 20Y, 20M, 20C, and 20K are apparatuses that form toner images using Y (yellow), M (magenta), C (cyan), and K (black) toners, respectively. It is. Since these four image forming engines 20Y, 20M, 20C, and 20K all have the same configuration, the image forming engine 20Y will be described here as an overview.

  The image forming engine 20Y includes a photoconductor 21Y that rotates in the direction indicated by an arrow B in FIG. 1, and a charger 22Y, a developing device 23Y, and a cleaner 24Y are disposed around the photoconductor 21Y. A transfer device 25Y is placed at a position where an intermediate transfer belt 31 described later is sandwiched between the photoreceptor 21Y.

  An exposure unit 26 is disposed below the four image forming engines 20Y, 20M, 20C, and 20K. Image data for exposure light modulation in the exposure unit 26 generated by the control unit 10 is input to the exposure unit 26. The exposure device 26 emits exposure light 261Y, 261M, 261C, and 261K corresponding to each of the image forming engines 20Y, 20M, 20C, and 20K, which is a light beam modulated based on the input image data. The The photosensitive members 21Y, 21M, 21C, and 21K constituting the image forming engines 20Y, 20M, 20C, and 20K are irradiated with the exposure lights 261Y, 261M, 261C, and 261K.

  Here, the photoreceptor 21 </ b> Y has a drum shape, holds charges by charging, discharges the charges by exposure, and holds an electrostatic latent image on the surface thereof. The photoreceptor 21Y corresponds to an example of an image carrier referred to in the present invention.

  The charger 22Y charges the surface of the photoreceptor 21Y to a certain charging potential.

  Further, the exposure device 26 emits exposure light 261Y modulated according to the input image data. After being charged by the charger 22Y, the photoreceptor 21Y is irradiated with the exposure light 261Y from the exposure device 26, and an electrostatic latent image is formed on the surface of the photoreceptor.

  The photoreceptor 21Y is irradiated with exposure light 261Y to form an electrostatic latent image on the surface thereof, and then developed by the developing unit 23Y. A toner image (yellow in this image forming engine 20Y is formed on the surface of the photoreceptor 21Y). (Y) toner image) is formed.

  An intermediate transfer unit 30 having an intermediate transfer belt 31 is provided on the four image forming engines 20Y, 20M, 20C, and 20K. The intermediate transfer unit 30 is an example of the intermediate transfer assembly of the present invention.

  The toner image formed on the photoreceptor 21Y by development by the developing unit 23Y is transferred onto the intermediate transfer belt 31 by the action of the transfer unit 25Y.

  The toner remaining on the photoreceptor 21Y after this transfer is removed from the photoreceptor 21Y by the cleaner 24Y.

  The intermediate transfer belt 31 is an endless belt that is looped around a plurality of rolls 32 and circulates in the direction of arrow C.

  The toner images of the respective color toners formed by the image forming engines 20Y, 20M, 20C, and 20K are sequentially transferred onto the intermediate transfer belt 31 so as to overlap each other and are transferred to the secondary transfer position where the secondary transfer device 41 is disposed. Be transported. In synchronization with this, the sheet that has been transported to the standby roll 16 is transported to the secondary transfer position, and the toner image on the intermediate transfer belt 31 is transported by the action of the secondary transfer unit 41. Transcribed above. The sheet that has received the transfer of the toner image is further conveyed, the toner image on the sheet is fixed on the sheet by pressurization and heating by the fixing device 50, and an image composed of the fixed toner image is formed on the sheet. Is done. The paper on which the image is formed is further conveyed and discharged onto the paper discharge tray 11.

  The intermediate transfer belt 31 after the toner image is transferred onto the paper by the secondary transfer device 41 further circulates, and the toner remaining on the surface is removed from the intermediate transfer belt 31 by the cleaner 42.

  Further, toner containers 43Y, 43M, 43C, and 43K that store toners of the respective colors are mounted above the intermediate transfer belt 31. The color toners stored in the toner containers 43Y, 43M, 43C, and 43K are consumed by the developing devices such as the developing device 23Y, which are respectively provided in the corresponding image forming engines 20Y, 20M, 20C, and 20K. Each developer is replenished accordingly.

  The control unit 10 controls the entire printer 102 in addition to converting image data input from the scanner 101 for exposure.

  Here, the copying machine 100 of the present embodiment has a color mode and a monochrome mode. The color mode is a mode in which a color image is formed using four image forming engines 20Y, 20M, 20C, and 20K. On the other hand, the monochrome mode is a mode in which a monochrome image is formed using only the image forming engine 20K that generates a toner image with black (K) toner among the four image forming engines 20Y, 20M, 20C, and 20K.

  In the color mode, the intermediate transfer belt 31 contacts all of the four photoconductors 21Y, 21M, 21C, and 21K provided in each of the four image forming engines 20Y, 20M, 20C, and 20K. On the other hand, in the monochrome mode, the intermediate transfer belt 31 uses black (K) toner of the four photosensitive members 21Y, 21M, 21C, and 21K to avoid unnecessary consumption of members that are not involved in image formation. Are in a retracted state apart from the three photoconductors 21Y, 21M, and 21C except for the photoconductor 21K for forming the.

  In the following, a contact / retraction switching mechanism of the intermediate transfer belt 31 accompanying switching between the color mode and the monochrome mode will be described.

  2 and 3 are schematic views of an intermediate transfer belt switching mechanism. FIG. 2 shows the state switched to the color mode, and FIG. 3 shows the state switched to the monochrome mode.

  Although the intermediate transfer belt 31 has been described as being wound around a plurality of rolls 32 in FIG. 1, the plurality of rolls 32 include a drive roll 321, two idler rolls 322, 323, a tension roll 324, and It is comprised with the opposing roll 325. The drive roll 321 is a roll that circulates and moves the intermediate transfer belt 31 in the direction of arrow C, and the tension roll 324 is a roll that brakes the posture of the intermediate transfer belt 31 by controlling the tension of the intermediate transfer belt 31. . The opposing roll 325 is a roll that faces the secondary transfer device 41 (see FIG. 1) and receives the pressing force of the secondary transfer device 41 pressed against the intermediate transfer belt 31.

  Inside the intermediate transfer belt 31, links 33Y, 33M, 33C, and 33K corresponding to the photoreceptors 21Y, 21M, 21C, and 21K are provided. These links 33Y, 33M, 33C, and 33K are supported by a frame (not shown) of the intermediate transfer unit 30 so as to be rotatable around the rotation shafts 331Y, 331M, 331C, and 331K, respectively.

  Further, the transfer units 25Y, 25M, 25C, and 25K are supported at the front ends of the links 33Y, 33M, 33C, and 33K, and the rear ends that sandwich the rotation shafts 331Y, 331M, 331C, and 331K are The springs 34Y, 34M, 34C, and 34K are urged against the frame of the intermediate transfer unit 30. These springs 34Y, 34M, 34C, 34K are all tension springs, and the transfer devices 25Y, 25M, 25C, 25K supported at the tips of the links 33Y, 33M, 33C, 33K are used as the intermediate transfer belt 31. It is energized in the direction of pressing.

  Further, a slider 35 is further provided inside the intermediate transfer belt 31. The slider 35 slides in a direction along the plurality of photoconductors 21Y, 21M, 21C, and 21K, and the remaining of the four links 33Y, 33M, 33C, and 33K except for the link 33K corresponding to black (K). The three links 33Y, 33M, and 33C are rotated around the rotation shafts 331Y, 331M, and 331C between the state shown in FIG. 2 and the state shown in FIG.

  The link 33K is biased by a spring 34K, and is maintained in a state in which the transfer device 25K at the tip thereof is rotated to push the intermediate transfer belt 31 from the inner side, regardless of the movement of the slider 35. As a result, the intermediate transfer belt 31 is in contact with the black (K) photoreceptor 21K regardless of the color mode or the monochrome mode.

  When switching from the monochrome mode to the color mode, the slider 35 slides in the direction of the arrow D shown in FIG. 2 (an example of the “second direction” in the present invention). Then, each link 33Y, 33M, 33C is released from the slider 35 and rotated by the urging force of each spring 34Y, 34M, 34C, and each transfer device 25Y, 25M, 25C at the tip of each link 33Y, 33M, 33C is in the middle. Pressed against the transfer belt 31. As a result, the intermediate transfer belt 31 comes into contact with the photoreceptors 21Y, 21M, and 21C. The slider 35 also moves the idler roll 322 via a cam mechanism (not shown). When the slider 35 moves to the position shown in FIG. 2 in the direction of arrow D, the idler roll 322 also moves to the position shown in FIG.

  On the other hand, at the time of switching from the color mode to the monochrome mode, the slider 35 slides in the direction of the arrow E shown in FIG. 3 (an example of “first direction” in the present invention), and the slider 35 has three links 33Y. , 33M, 33C are rotated to the state shown in FIG. 3 against the biasing force of the springs 34Y, 34M, 34C. Then, the transfer devices 25Y, 25M, and 25C at the tips of the links 33Y, 33M, and 33C stop pressing the intermediate transfer belt 31, and the intermediate transfer belt 31 is separated from the photoreceptors 21Y, 21M, and 21C. At this time, the idler roll 322 also moves to the position shown in FIG. 3 as the slider 35 slides in the direction of arrow E.

  2 and 3, a cam shaft 36 (not shown in FIGS. 2 and 3, see FIGS. 4 and 5) extends in the direction perpendicular to the paper surface. 361 is fixed. When the cam shaft 36 rotates, the slider 35 slides between the state shown in FIG. 2 and the state shown in FIG. 3 due to the interference between the rotary cam 361 and the slider 35. Further, a brake 37 is attached to the cam shaft 36, and the brake 37 is urged by a spring 39 between the cam 37. The magnitude of the braking force by the brake 37 is determined by the strength of the biasing force of the spring 39, and the stronger the biasing force, the stronger the braking force acts on the rotation of the cam shaft 36. Here, at the time of transition from the monochrome mode (FIG. 3) to the color mode (FIG. 2), the cam shaft rotates and the engagement of the rotary cam 361 with the slider 35 is loosened, and the slider 35 is linked to the links 33Y and 33M. , 33C is slid in the direction of the arrow D shown in FIG. 2 by the urging force of the springs 34Y, 34M, 34C urging 33C. For this reason, when the brake 37 is not provided, the links 33Y, 33M, and 33C rotate vigorously, the transfer units 25Y, 25M, and 25C strike the intermediate transfer belt 31 vigorously, and a large collision sound is generated.

  On the other hand, in the present embodiment, since the brake 37 and the spring 39 that determines the braking force of the brake 37 are provided, the transfer units 25Y, 25M, and 25C slowly hit the intermediate transfer belt 31, and the collision sound is softened.

  In the present embodiment, the links 33Y, 33M, and 33C correspond to an example of the pressing member according to the present invention, and the springs 34Y, 34M, and 34C correspond to an example of the first biasing member according to the present invention. The slider 35 corresponds to an example of a slide member according to the present invention, the cam shaft 36 (see FIGS. 4 and 5) corresponds to an example of a cam shaft according to the present invention, and the rotary cam 361 corresponds to an example of a cam member according to the present invention. To do. Further, the brake 37 corresponds to an example of a braking member according to the present invention, and the spring 39 corresponds to an example of a second urging member according to the present invention.

  In the following, the matters related to the sliding operation of the slider shown in FIGS. 2 and 3 will be further described with reference to schematic diagrams.

  4 and 5 are a plan view and a side view, respectively, showing the slider and the rotating cam. 4A and 5B, FIG. 4A shows a color mode, and FIG. 5B shows a monochrome mode. 4 and 5, the same reference numerals as those in FIGS. 2 and 3 are given to the same elements as those in the intermediate transfer unit 30 shown in FIGS.

  Although only one slider 35 shown in FIG. 4 is provided, two sliders 35 are actually provided, one on each side in the width direction of the intermediate transfer belt 31, and the configuration around the slider 35 is symmetrical with respect to the width direction. It is configured. However, the brake 37 and the spring 39 for urging the brake 37 are provided only on one side shown here. FIG. 4 shows a part of the frame 301 of the intermediate transfer unit 30 (see FIGS. 1 to 3). The frame 301 of the intermediate transfer unit 30 is arranged so as to sandwich the two sliders 35 on both sides in the width direction of the intermediate transfer belt 31 from the outside. The cam shaft 36 is rotatably supported by the frames 301 on both sides. Links 33Y, 33M, and 33C (see FIGS. 2 and 3; only the link 33C is shown in FIGS. 4 and 5) are also rotatably supported by the frame 301.

  When the slider 35 is in the color mode state shown in FIGS. 4A and 5A, when the cam shaft 36 is rotated by a motor (not shown), the rotating cam 361 pushes the slider 35 in the direction of arrow E. The slider 35 slides in the direction of the arrow E. Then, the cam shaft 36 receives a reaction force in the direction opposite to the direction of the arrow E via the rotary cam 361 by the slider 35. Here, the spring 39 that applies the urging force to the brake 37 is a fairly strong tension spring. Therefore, in the monochrome mode, as shown in FIG. 4B, the spring 39 of the cam shaft 36 is more than the rotary cam 361. The portion near the end urged by the bending is bent, and the spring 39 is contracted accordingly.

  In other words, the spring 39 changes from the state after the slider 35 slides in the direction of arrow E shown in FIGS. 4B and 5B (monochrome mode state) to FIGS. When it slides in the direction of the arrow D shown in (A) (at the time of transition to the color mode), it expands.

  As described above, the spring 39 determines the braking force of the brake 37, and the stronger the spring 39, the stronger the braking force acts on the rotation of the cam shaft 36. Therefore, when the slider 35 moves in the direction indicated by the arrow D along with the transition from the monochrome mode to the color mode, a stronger braking force can be obtained at the end of the movement than at the initial stage. That is, the transfer devices 25Y, 25M, and 25C at the tips of the links 33Y, 33M, and 33C move quickly from the state where they are moved away from the intermediate transfer belt 31 toward the intermediate transfer belt 31, and move quickly. , 25M, 25C push the intermediate transfer belt 31, and the intermediate transfer belt 31 moves slowly at the end when it hits the photoreceptors 21Y, 21M, 21C. Accordingly, both the speed of switching from the monochrome mode to the color mode and the reduction of the collision sound are compatible with each other at a higher level than when the spring 39 does not expand and contract.

  Further, as described above, a total of two sliders 35 are disposed on each side of the intermediate transfer belt 31. Correspondingly, the number of cam shafts 36 is one, but the rotating cams 361 are fixed at positions corresponding to the two sliders 35 of the cam shaft 36, respectively. On the other hand, only one brake 37 and one brake 37 are attached to this one camshaft 36, and only one spring 39 is provided correspondingly.

  Patent Document 3 described above discloses that a spring is attached to the slider. In this case, it is necessary to attach a spring to each of the two sliders. In the case of this embodiment, only one spring 39 is required, which contributes to cost reduction.

  In the case of this embodiment, the two sliders 35 provided on both sides of the intermediate transfer belt 31 are moved by one cam shaft. For this reason, in the case of this embodiment, regardless of whether the spring 39 is one or the brake 37 is disposed at each end of the cam shaft 36 and the two springs 39 are provided correspondingly. The slider 35 can be moved simultaneously. On the other hand, in Patent Document 3 described above, it is necessary to provide a spring for each of two sliders which are separate members, and the two sliders always move by the same amount of movement simultaneously due to variations in spring strength. However, the two sliders may move differently. If there is a difference between the movements of the two sliders, one end of the transfer unit will hit the intermediate transfer belt first and the other end will hit later in the width direction of the intermediate transfer belt. Then, there is a possibility that a force in the width direction is applied to the intermediate transfer belt and the intermediate transfer belt is shifted to the width direction. Even if the intermediate transfer belt is offset, it is adjusted to the correct position by, for example, the tension roll 324 shown in FIGS. 2 and 3 or a member corresponding thereto, but it takes time. That is, according to the configuration of the present embodiment, it is possible to quickly shift to the image forming operation after shifting from the monochrome mode to the color mode as compared with the configuration disclosed in Patent Document 3.

  Further, as shown in FIG. 4, the brake 37 is arranged outside the frame 301 of the intermediate transfer unit 30 (see FIGS. 1 to 3), so that it is compared with the case where it is arranged inside the frames 301 on both sides. Even if the brake 37 slides on the cam shaft 36 to generate foreign matter, the possibility that the foreign matter adversely affects the intermediate transfer belt 31 and other elements to cause image defects is reduced.

  FIG. 6 is a diagram showing a second example of how to attach a spring that determines the braking force of the brake. 6A and 6B respectively correspond to FIGS. 4A and 4B in the above-described embodiment. However, in FIG. 6, illustration of the arm 33 </ b> C, the transfer device 25 </ b> C, and the like shown in FIGS. 4 and 5 is omitted.

  In the example shown in FIG. 4, the spring 39 is suspended between the brake 37 and the shaft 38 fixed to the frame 301. On the other hand, in the example shown in FIG. 6, the spring 39 is hung between the brake 37 and the shaft 381. The shaft 381 is rotatably supported by both the frame 301 and the slider 35. In the case of this configuration, in the color mode state shown in FIG. 6A, compared to the monochrome mode state shown in FIG. In addition, the spring 39 can be expanded and contracted by the movement of the shaft 381. For this reason, when moving from the monochrome mode to the color mode, the slider 35 can be moved quickly at the beginning and slowly at the end so that the speed of the switching operation and the reduction of the collision sound can be achieved at a higher level. it can.

20Y, 20M, 20C, 20K Image forming engine 21Y, 21M, 21C, 21K Photoconductor 26 Exposure unit 30 Intermediate transfer unit 31 Intermediate transfer belt 33Y, 33M, 33C, 33K Link 34Y, 34M, 34C, 34K, 39 Spring 35 Slider 36 Cam shaft 37 Brake 38, 381 Shaft 41 Secondary transfer device 100 Copier 101 Scanner 102 Printer 301 Frame 322, 323 Idler roll 324 Tension roll 325 Opposing rolls 331Y, 331M, 331C, 331K Rotating shaft 361 Rotating cam

Claims (5)

A plurality of image holders for receiving toner image formation while rotating and holding the toner image;
The toner image transferred through the moving path along the plurality of image carriers and circulatingly moving in contact with at least a part of the plurality of image carriers is received by the image carrier, The intermediate transfer belt for secondary transfer of the toner image to the recording medium and the image holding member are disposed at positions where the movement path is sandwiched, and the intermediate transfer belt passing through the movement path can be pressed and retracted freely. A pressing member that brings the intermediate transfer belt into contact with a part of the plurality of image holding members to which the intermediate transfer belt contacts and separates by pressing, and the intermediate transfer belt is pressed against the pressing member. A first urging member that urges the pressing member in a direction to be moved, and a slide that is slidable in a direction along the plurality of image holding bodies and that is slid in the first direction, whereby the pressing member is moved to the first direction. Retreating against the biasing force of the biasing member, A slide member that causes the pressing member to press the intermediate transfer belt by sliding in a second direction opposite to the first direction, and extends and rotates in a width direction that intersects the circulating movement direction of the intermediate transfer belt. A cam shaft, a cam member fixed to the cam shaft and interfering with the slide member to slide the slide member according to the rotation of the cam shaft; An intermediate transfer assembly having a braking member for applying braking, and a second urging member for urging the braking member to control the strength of braking by the braking member; An image forming apparatus comprising: a fixing device that fixes the toner image on a recording medium that has undergone next transfer.   The second urging member is a tension spring, and the intermediate transfer assembly is moved when the slide member slides in the second direction from the state after the slide member slides in the first direction. The image forming apparatus according to claim 1, wherein the two urging members are extended. The intermediate transfer assembly is fixed to the camshaft at each position where the pair of slide members respectively disposed at positions separated from each other in the width direction, and at each position where the pair of slide members are disposed, A pair of cam members that simultaneously slide a pair of slide members in the first direction and the second direction,
The image forming apparatus according to claim 1, wherein only one braking member is attached to the camshaft. The intermediate transfer assembly has a pair of support members that are disposed at positions sandwiching the pair of slide members from both sides in the width direction and rotatably support both ends of the cam shaft,
The image forming apparatus according to claim 3, wherein the braking member and the second urging member are disposed on the outer side in the width direction of one of the pair of supporting members. The toner image is formed while rotating, passes through a moving path along a plurality of image holding bodies that hold the toner image, and circulates while contacting at least some of the plurality of image holding bodies. An intermediate transfer belt that receives the transfer of the toner image held by the image carrier and secondarily transfers the toner image to a recording medium;
The intermediate member of the plurality of image carriers is disposed at a position sandwiching the movement path between the image carrier and the intermediate transfer belt passing through the movement path so as to press and retract freely. A pressing member for bringing the intermediate transfer belt into contact with a part of the image carrier to which the transfer belt comes in contact with and away from, and
A first urging member that urges the pressing member in a direction to press the intermediate transfer belt against the pressing member;
The pressing member is retracted against the urging force of the first urging member by sliding in a first direction and slidable in a direction along the plurality of image holding members, A slide member that causes the pressing member to press the intermediate transfer belt by sliding in a second direction opposite to the direction;
A camshaft extending and rotating in a width direction intersecting with the circulating movement direction of the intermediate transfer belt;
A cam member that is fixed to the cam shaft and interferes with the slide member to slide the slide member in accordance with the rotation of the cam shaft;
A braking member that receives sliding of the cam shaft and brakes rotation of the cam shaft;
An intermediate transfer assembly comprising: a second urging member that urges the braking member to control the strength of braking by the braking member.

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