JP5483017B2 - Belt device and image forming apparatus - Google Patents

Description

  The present invention relates to a belt device and an image forming apparatus including the belt device.

  In an image forming apparatus such as a copying machine, a printer, a facsimile, or a complex machine of these, a plurality of photosensitive drums as an image carrier that carries an image on a surface, and a plurality of image forming units that perform image forming processing on the photosensitive drum. A so-called tandem type that is arranged side by side is known. In this tandem type image forming apparatus, an image on each photosensitive drum is sequentially transferred to an intermediate transfer belt used as an intermediate transfer body by a primary transfer device, and then an image on the intermediate transfer belt is transferred to a secondary transfer device. There are an intermediate transfer type that batch-transfers images onto transfer paper such as a sheet, and a direct transfer type that directly transfers images on each photosensitive drum sequentially onto transfer paper conveyed by a transfer belt by a transfer device. .

  Further, in an image forming apparatus provided with a belt such as the intermediate transfer belt or the conveyor belt, in order to prevent permanent deformation of the belt due to the same portion of the belt coming into contact with the photosensitive drum for a long time, In order to suppress wear of the color photosensitive drum and the color developing device at the time of forming a monochrome image, the belt is separated from the color photosensitive drum. Some are configured to be spaced apart.

  2. Description of the Related Art Conventionally, as a belt contacting / separating mechanism for bringing a belt into and out of a photosensitive drum, for example, a roller that supports the belt can be moved toward and away from the photosensitive drum by a rotatable rotating member (arm) What was comprised is disclosed (refer patent document 1 or 2).

FIG. 18 is a diagram schematically showing the conventional belt contact / separation mechanism.
In the configuration shown in FIG. 18, one end 400 a of a rotatable arm-shaped rotation member 400 is attached to the roller 300 that supports the belt 200, and the other end 400 b of the rotation member 400 has an urging member. The coil spring 500 is in contact. Further, a moving member 600 capable of reciprocating in the horizontal direction is disposed on the other end 400 b side of the rotating member 400.

  When the belt 200 is separated from the photosensitive drum 100, the moving member 600 is moved in the direction of the arrow A in the figure against the urging force of the coil spring 500, and the rotating member 400 is moved counterclockwise by the moving member 600 in the figure. Rotate around. As a result, the roller 300 moves in a direction away from the photosensitive drum 100, and the belt 200 is separated from the photosensitive drum 100. When the belt 200 is brought into contact with the photosensitive drum 100, the moving member 600 is moved in the direction indicated by the arrow B in the figure. As a result, the rotating member 400 is rotated in the clockwise direction in the drawing by the urging force of the coil spring 500, and the roller 300 moves in a direction approaching the photosensitive drum 100, so that the belt 200 is moved to the photosensitive drum 100. Make contact.

  However, as shown in FIG. 19, the contact / separation mechanism of the belt causes the contact surface of the rotating member 400 to be inclined with respect to the coil spring 500 as the rotating member 400 rotates. Will bend. As a result, there is a problem that the posture of the coil spring 500 becomes unstable or abnormal noise is generated when the coil spring 500 comes into contact with a peripheral member. In the worst case, the coil spring 500 is caught by the peripheral members and the rotating member 400 cannot be urged, and the belt 200 cannot contact the photosensitive drum 100, and there is a risk of image failure.

  Therefore, in view of such circumstances, the present invention intends to provide a belt device capable of preventing problems such as abnormal noise caused by bending of a biasing member, and an image forming apparatus including the belt device. .

  The invention of claim 1 is configured to be rotatable between a belt member, a belt support member that supports the belt member, and a first position and a second position for moving the belt support member. And a biasing member that abuts on the pivoting member and biases the pivoting member toward the first position. The pivoting member includes the first position. A first abutting surface with which the urging member abuts when disposed at a second position, and a second abutting surface with which the urging member abuts when disposed at the second position. is there.

  When the rotation member is rotated between the first position and the second position, the biasing member may be brought into contact with a different surface (first contact surface or second contact surface). Therefore, the inclination of the first contact surface and the second contact surface with respect to the urging member can be reduced as compared with the conventional case. Thereby, the bending of the urging member accompanying the rotation of the rotating member can be suppressed, and the generation of noise due to the urging member contacting the peripheral member can be prevented. Further, by suppressing the deflection of the biasing member and stabilizing the posture, it is possible to prevent a problem that the biasing member is caught by the peripheral member and does not function.

  According to a second aspect of the present invention, in the belt device according to the first aspect, the rotation angle at which the rotation member rotates between the first position and the second position is set to the first contact. This is set to the same angle as the angle formed between the contact surface and the second contact surface.

  By setting the angle formed by the first contact surface and the second contact surface to the same angle as the rotation angle at which the rotation member rotates between the first position and the second position, In any case where the rotating member is disposed at either the first position or the second position, the inclination of the first contact surface and the second contact surface with respect to the biasing member can be reduced. Become. Thereby, it becomes possible to suppress the said malfunction by the biasing member bending more highly.

  The invention of claim 3 is the belt device according to claim 1 or 2, wherein both the first contact surface and the second contact surface are in contact with the biasing member, The urging member is disposed so as to be orthogonal to the urging direction of the urging member.

  Both the first contact surface and the second contact surface are disposed so as to be orthogonal to the biasing direction of the biasing member while being in contact with the biasing member. Since the bending of the urging member can be eliminated, the above-described problem caused by the bending of the urging member can be suppressed to a higher degree.

  According to a fourth aspect of the present invention, in the belt device according to any one of the first to third aspects, the first contact surface and the first contact surface are bent by bending a surface of the rotating member with which the biasing member contacts. A second contact surface is formed.

  Thereby, the first contact surface and the second contact surface can be formed with a simple configuration.

  According to a fifth aspect of the present invention, in the belt device according to the fourth aspect, a bent portion between the first contact surface and the second contact surface is formed in a curved surface shape.

  By forming a bent portion between the first contact surface and the second contact surface into a curved surface, the space between the first contact surface and the second contact surface of the biasing member Can be moved smoothly. As a result, the rotating member can be smoothly rotated.

  According to a sixth aspect of the present invention, in the belt device according to any one of the first to fifth aspects, the urging member is constituted by a coil spring, and the coil member is inserted into the coil spring by the rotating member. Protrusions that hold the spring are provided.

  Thus, by inserting a convex part in a coil spring, a coil spring can be hold | maintained by a convex part and the shift | offset | difference and detachment | leave of a coil spring with respect to the contact surface of a rotation member can be prevented.

  The invention of claim 7 is the belt device according to claim 6, wherein the angle formed by both side surfaces of the convex portion in a cross section obtained by cutting the convex portion by a plane orthogonal to the rotational axis of the rotational member is The rotation member is set to the same angle as the rotation angle at which the rotation member rotates between the first position and the second position.

  In the cross section, by setting the angle formed by the both side surfaces of the convex portion to the same angle as the rotation angle at which the rotation member rotates between the first position and the second position, When it rotates, it can avoid that the internal peripheral surface of a coil spring is pressed by a convex part. Thereby, it can prevent that a coil spring curves by press of a convex part.

  According to an eighth aspect of the present invention, there is provided a belt device according to any one of the first to seventh aspects, wherein a third contact disposed between the first contact surface and the second contact surface is provided. A contact member having a contact surface is provided so as to be rotatable about a rotation axis that is parallel to the rotation axis of the rotation member.

  In this case, even if the rotation member rotates, the third contact surface and the biasing member of the contact member are maintained in a state of being orthogonal to each other or in a state close thereto. For this reason, even if the surface on which the urging member abuts is switched between the first abutment surface and the second abutment surface as the rotation member rotates, the urging member is always in the first position. 3 is held in contact with the contact surface 3. Thereby, the receiving area with respect to the biasing member can be ensured, and the posture of the biasing member can be further stabilized.

  The invention according to claim 9 is the belt device according to claim 8, wherein the third contact surface is provided with a convex portion that is inserted into the coil spring as the biasing member and holds the coil spring. The outer diameter of the convex portion is formed larger than the inner diameter of the coil spring, and the convex portion is press-fitted into the coil spring.

  By press-fitting the convex portion into the coil spring, the bending of the coil spring accompanying the rotation of the rotation member can be more stably suppressed. In addition, when the protrusion is press-fitted into the coil spring and the contact member and the coil spring are set as subassemblies, they can be integrally assembled to the rotating member, and productivity is improved. Further, as described above, even when the rotating member rotates, the third contact surface and the coil spring are maintained in a state of being orthogonal to each other or close to each other. Even if they are integrally attached, problems such as bending of the coil spring do not occur.

  According to a tenth aspect of the present invention, in the belt device according to the eighth or ninth aspect, the length of the third abutting surface in a direction orthogonal to the rotation axis of the abutting member is used as the biasing member. It is formed larger than the outer diameter of the coil spring.

  Thereby, a large contact surface of the coil spring can be secured, and the posture of the coil spring can be further stabilized.

  The invention of claim 11 is the belt device according to any one of claims 8 to 10, wherein the rotation shaft of the contact member includes the first contact surface and the second contact surface. It is arrange | positioned in the position between.

  In this case, when the rotating member is disposed at the first position, the urging member contacts the first contact surface and the third contact surface, and the rotating member is disposed at the second position. Then, the biasing member comes into contact with the second contact surface and the third contact surface. Thereby, even if it is a case where a rotation member is arrange | positioned in any of a 1st position and a 2nd position, the receiving area with respect to a biasing member can be ensured, and the attitude | position of a biasing member is stabilized more. It becomes possible.

  A twelfth aspect of the invention is the belt device according to any one of the eighth to eleventh aspects, wherein the rotating member is provided with a notch portion formed larger than the contact member, and the inside of the notch portion is provided. The abutting member is disposed on the surface.

  By accommodating the abutting member in the notch, the size of the rotating member does not increase even if the abutting member is provided, so that the apparatus can be downsized.

  According to a thirteenth aspect of the present invention, in the belt device according to the twelfth aspect, a gap of less than 5 mm is provided between both end portions of the abutting member in a direction perpendicular to the rotation axis and the notch portions facing each other. Is provided.

  By providing a gap of less than 5 mm between both end portions of the contact member in the direction orthogonal to the rotation axis and the notch portions facing them, interference between the contact member and the notch portion is prevented. A smooth rotation of the contact member can be ensured, and an increase in the size of the apparatus can be prevented.

  According to a fourteenth aspect of the present invention, in the belt device according to any one of the eighth to thirteenth aspects, the rotating member is provided with a receiving portion that directly receives and supports the rotating shaft of the abutting member. is there.

  By providing the receiving portion that directly receives the rotation shaft of the contact member, the contact member can be supported without adding new components, and the number of components can be reduced.

  According to a fifteenth aspect of the present invention, in the belt device according to the fourteenth aspect, the receiving portion has an opening for inserting the rotating shaft of the abutting member, and the biasing member serves as the opening. It arrange | positions so that it may open to the surface side contact | abutted to the said rotation member.

  Thus, by arranging the opening of the receiving portion, the contact member can be easily attached to the receiving portion. Further, after the attachment, the contact member is urged by the urging member in the direction opposite to the opening of the receiving portion, so that the contact member can be prevented from falling off the receiving portion.

  According to a sixteenth aspect of the present invention, in the belt device according to any one of the first to fifteenth aspects, the belt member is an intermediate transfer belt to which an image on an image carrier is transferred, and the belt support member. Is a transfer member for transferring an image on the image carrier onto the intermediate transfer belt, and the transfer member is configured to contact and separate from the image carrier by the rotating member. .

  By applying the configuration of the present invention to the belt device of the indirect transfer system including the intermediate transfer belt, it is possible to suppress the deflection of the biasing member accompanying the rotation of the rotating member, as described above. Generation of abnormal noise due to contact with peripheral members can be prevented. In addition, by suppressing the deflection of the urging member and stabilizing the posture, there is no possibility of image failure caused by the urging member being caught by the peripheral member, and the reliability is improved.

  According to a seventeenth aspect of the present invention, in the belt device according to the first to fifteenth aspects, the belt member is a conveyance belt that carries and conveys a sheet-like recording medium, and the belt support member is the conveyance belt. As a transfer member for transferring an image on the image carrier to the upper recording medium, the transfer member is configured to be brought into contact with and separated from the image carrier by the rotating member.

  By applying the configuration of the present invention to the belt device of the direct transfer system including the conveyance belt, similarly to the above, it is possible to suppress the bending of the urging member accompanying the rotation of the rotating member, and the urging member Generation of abnormal noise due to contact with peripheral members can be prevented. In addition, by suppressing the deflection of the urging member and stabilizing the posture, there is no possibility of image failure caused by the urging member being caught by the peripheral member, and the reliability is improved.

  An eighteenth aspect of the invention is an image forming apparatus including the belt device according to any one of the first to seventeenth aspects.

  Since the image forming apparatus includes the belt device according to any one of claims 1 to 17, the above-described effect by these belt devices can be obtained.

  According to the present invention, since the bending of the urging member can be suppressed, it is possible to prevent the generation of noise due to the urging member contacting the peripheral member. Further, by suppressing the deflection of the biasing member and stabilizing the posture, it is possible to prevent a problem that the biasing member is caught by the peripheral member and does not function, and the reliability is improved.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a perspective view of a transfer device mounted on the image forming apparatus. FIG. 3 is a diagram illustrating a state where an intermediate transfer belt included in the transfer device is in contact with a photosensitive drum of each color. FIG. 2 is a diagram illustrating a state in which an intermediate transfer belt included in the transfer device is separated from a color photosensitive drum. It is an enlarged view which shows the structure which concerns on 1st Embodiment of the rotation member which the said transfer apparatus has. It is a figure which shows the state which has arrange | positioned the said rotation member in the 1st position. It is a figure which shows the state which has arrange | positioned the said rotation member in the 2nd position. It is an enlarged view which shows the structure of 2nd Embodiment of the said rotation member. It is a perspective view of the convex part provided in the said rotation member. It is an enlarged view which shows the structure of 3rd Embodiment of the said rotation member. It is an enlarged view which shows the structure of 4th Embodiment of the said rotation member. It is an enlarged view which shows the structure of 4th Embodiment of the said rotation member. It is a figure which shows the state which has arrange | positioned the said rotation member in the 1st position. It is a figure which shows the state which has arrange | positioned the said rotation member in the 2nd position. It is an enlarged view which shows the structure of 5th Embodiment of the said rotation member. It is an enlarged view which shows the structure of 6th Embodiment of the said rotation member. 1 is a diagram illustrating an example of a direct transfer type image forming apparatus. It is the figure which represented the conventional contact / separation mechanism of the belt typically. It is a figure which shows the state which the contact surface of the rotation member inclined with respect to the coil spring.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.
The image forming apparatus shown in FIG. 1 includes four process units 1Y, 1M, 1C, and 1Bk as image forming units. Each process unit 1Y, 1M, 1C, 1Bk is configured to be detachable from the image forming apparatus main body 50. The process units 1Y, 1M, 1C, and 1Bk have the same configuration except that they contain toners of different colors of yellow, magenta, cyan, and black corresponding to the color separation components of the color image.

  Specifically, each of the process units 1Y, 1M, 1C, and 1Bk serves as a photosensitive drum 2 as an electrostatic latent image carrier (or image carrier) and a charging unit that charges the surface of the photosensitive drum 2. A charging roller 3, a developing roller 4 as a developing unit that visualizes an electrostatic latent image on the photosensitive drum 2, a cleaning blade 5 as a cleaning unit that cleans the surface of the photosensitive drum 2, and the like are provided. . In FIG. 1, only the photosensitive drum 2, the charging roller 3, the developing roller 4, and the cleaning blade 5 included in the yellow process unit 1 </ b> Y are denoted by reference numerals. Is omitted.

  In FIG. 1, an exposure device 6 as an exposure means for exposing the surface of the photosensitive drum 2 is disposed above each process unit 1Y, 1M, 1C, 1Bk. On the other hand, a transfer device 7 is disposed below the process units 1Y, 1M, 1C, and 1Bk. The transfer device 7 has an intermediate transfer belt 8 constituted by an endless belt member as a transfer body. The intermediate transfer belt 8 is stretched over and supported by a plurality of rollers 9, 10 and 11 as belt support members. In the present embodiment, the roller 9 disposed at the right end of the intermediate transfer belt 8 in the drawing functions as a driving roller, and the roller 10 disposed at the left end in the drawing functions as a tension roller. The driving roller 9 is configured so as to obtain a driving force from a driving means (not shown) and rotationally drive it counterclockwise in the figure. By the rotation of the driving roller 9, the intermediate transfer belt 8 is moved in the direction of the arrow in the figure. It can be rotated. The tension roller 10 is urged toward the intermediate transfer belt 8 by an urging means (not shown), whereby a predetermined tension is applied to the intermediate transfer belt 8.

  Four rollers 11 disposed at positions facing the respective photosensitive drums 2 are primary transfer rollers as transfer members for primarily transferring an image on the photosensitive drum 2 to the intermediate transfer belt 8. A primary transfer nip as a transfer portion is formed at a position where the intermediate transfer belt 8 is sandwiched between each primary transfer roller 11 and each photosensitive drum 2. A secondary transfer roller 12 as a transfer member for secondary transfer of the image on the intermediate transfer belt 8 to the recording paper is disposed at a position facing the drive roller 9. A secondary transfer nip as a transfer portion is formed at a position where the intermediate transfer belt 8 is sandwiched between the secondary transfer roller 12 and the driving roller 9.

  A belt cleaning device 13 for cleaning the surface of the intermediate transfer belt 8 is disposed on the outer peripheral surface of the intermediate transfer belt 8 on the right end side in the drawing. A waste toner transfer hose (not shown) is attached from the belt cleaning device 13, and the tip of the toner transfer hose is connected to an inlet portion of a waste toner container 14 disposed below the transfer device 7.

  A lower part of the image forming apparatus main body 50 is provided with a paper feed tray 15 that stores recording paper P as a sheet-like recording medium, a paper feed roller 16 that carries the recording paper P out of the paper feed tray 15, and the like. On the other hand, a pair of paper discharge rollers 17 for discharging the recording paper to the outside and a paper discharge tray 18 for stocking the discharged recording paper are disposed on the upper portion of the image forming apparatus main body 50. .

  In the image forming apparatus main body 50, a conveyance path R for guiding recording paper from the lower paper feed tray 15 to the upper paper discharge tray 18 is formed. A pair of registration rollers 19 is disposed on the conveyance path R in the middle from the paper feed roller 16 to the secondary transfer roller 12. In addition, a fixing device 20 for fixing an image on the recording paper is provided on the way from the secondary transfer roller 12 to the paper discharge roller 17. The fixing device 20 includes a fixing roller 21 as a fixing member that is heated by a heat source, and a pressure roller 22 as a pressure member that presses the fixing roller 21. A fixing nip as a fixing unit is formed at a position where the fixing roller 21 and the pressure roller 22 are in pressure contact with each other.

The basic operation of the image forming apparatus will be described below with reference to FIG.
When the image forming operation is started, the photosensitive drums 2 of the process units 1Y, 1M, 1C, and 1Bk are rotationally driven clockwise by a driving device (not shown), and the surface of each photosensitive drum 2 is charged with the charging roller 3. Are uniformly charged to a predetermined polarity. The surface of each charged photoconductive drum 2 is irradiated with laser light from the exposure device 6 to form an electrostatic latent image on the surface of each photoconductive drum 2. At this time, the image information to be exposed on each photosensitive drum 2 is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. As the electrostatic latent image formed on the photosensitive drum 2 is supplied with toner by the developing rollers 4, the electrostatic latent image is visualized (visualized) as a toner image.

  By driving the drive roller 9 counterclockwise in the figure, the intermediate transfer belt 8 is driven to rotate in the direction indicated by the arrow in the figure. Further, a constant voltage or a constant current controlled voltage having a polarity opposite to the toner charging polarity is applied to each primary transfer roller 11. Thereby, a transfer electric field is formed at the primary transfer nip between each primary transfer roller 11 and each photosensitive drum 2. The toner images of the respective colors formed on the photosensitive drums 2 of the process units 1Y, 1M, 1C, and 1Bk are sequentially superimposed and transferred onto the intermediate transfer belt 8 by the transfer electric field formed in the primary transfer nip. Is done. Thus, the intermediate transfer belt 8 carries a full-color toner image on its surface. After the transfer of the toner image, the toner remaining on the surface of each photosensitive drum 2 is removed by the cleaning blade 5. Next, the surface of the photosensitive drum 2 is subjected to a static elimination action by a static eliminator (not shown), and the surface potential is initialized to prepare for the next image formation.

  When the image forming operation is started, the sheet feeding roller 16 starts rotating, and the recording sheet P stored in the sheet feeding tray 15 is sent out to the transport path R by the sheet feeding roller 16. The recording paper P sent out to the transport path R is temporarily stopped by the registration roller 19. Thereafter, the driving of the registration roller 19 is resumed, and the recording paper P is sent to the secondary transfer nip between the secondary transfer roller 12 and the drive roller 9 in synchronization with the toner image on the intermediate transfer belt 8. . At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 8 is applied to the secondary transfer roller 12, thereby forming a transfer electric field in the secondary transfer nip. When the recording paper P and the toner image on the intermediate transfer belt 8 reach the secondary transfer nip, the toner image on the intermediate transfer belt 8 is transferred onto the recording paper P by the transfer electric field formed in the secondary transfer nip. Are collectively transferred. Further, the toner remaining on the intermediate transfer belt 8 after the transfer is removed by the belt cleaning device 13, and the removed toner is conveyed to the waste toner container 14 and collected. The recording paper P to which the toner image has been transferred is conveyed to the fixing unit 20, and the recording paper P is heated and pressed by the fixing roller 21 and the pressure roller 22 to fix the toner image. Thereafter, the recording paper P is discharged to the paper discharge tray 18 by the paper discharge roller 17.

  The above description is an image forming operation when a full-color image is formed on a recording sheet. A single color image is formed using any one of the four process units 1Y, 1M, 1C, and 1Bk. Two or three process units may be used to form a two or three color image.

  Further, in the image forming apparatus of the present embodiment, when a monochrome image is formed using the black photosensitive drum 2, the intermediate transfer belt 8 is separated from the photosensitive drum 2 of a color other than black. doing. The belt contact / separation mechanism in the image forming apparatus will be described below.

FIG. 2 is a perspective view of the transfer device 7.
The three primary transfer rollers 11 shown in FIG. 2 are primary transfer rollers 11 disposed to face a photosensitive drum of a color other than black. Here, the primary transfer rollers 11 face the black photosensitive drum. 11 is omitted. As shown in FIG. 2, a rotatable member 23 is provided at the end of each color primary transfer roller 11. The rotating member 23 is formed in a substantially L-shaped arm shape, and its upper end 23 a is attached to the end of the primary transfer roller 11. On the other hand, a coil spring 24 as an urging means for urging the rotation member 23 is in contact with the lower end 23 b of each rotation member 23. The end of the coil spring 24 opposite to the end in contact with the rotating member 23 is positioned in contact with a receiving surface (not shown) provided in the image forming apparatus main body. In this case, the coil spring 24 is disposed in a compressed state, and the lower end 23b of the rotating member 23 is urged to the left in the drawing by the coil spring 24.

  In addition, a movable member 25 that can move in the horizontal direction is disposed over the position where each of the rotating members 23 is disposed. The moving member 25 has three contact portions 25 a that contact the lower end 23 b of each rotating member 23. Each contact portion 25a is in contact with the surface opposite to the contact surface with which the coil spring 24 of the rotating member 23 is in contact. An eccentric cam 26 attached to the rotary shaft 27 is disposed on the right end side of the moving member 25 in the drawing. The eccentric cam 26 is in contact with a receiving portion 25 b provided on the moving member 25, and the rotating shaft 27 to which the eccentric cam 26 is attached is inserted through a horizontal long hole 25 c formed in the moving member 25. The rotating shaft 27 is configured to rotate by receiving a driving force from a driving means (not shown).

  In FIG. 2, the rotating member 23, the coil spring 24, the moving member 25, and the eccentric cam 26 are disposed on one end side (the end side on the near side in the drawing) of the primary transfer roller 11. Although illustrated, they are similarly disposed on the other end side of the primary transfer roller 11.

Hereinafter, the belt contact / separation operation will be described with reference to FIGS. 3 and 4.
In the state shown in FIG. 3, the intermediate transfer belt 8 is in contact with the black photosensitive drum 2Bk and the color photosensitive drums 2Y, 2M, and 2C. When the eccentric cam 26 is rotated 180 degrees in this state, as shown in FIG. 4, the receiving portion 25b is pushed to the right side of the drawing by the eccentric cam 26, and the moving member 25 moves to the right side of the drawing. Along with the movement of the moving member 25, the lower end of each rotating member 23 is pushed to the right side in the figure by each abutting portion 25a, and each rotating member 23 rotates counterclockwise in the figure. As a result, the primary transfer rollers 11 move in the direction away from the color photosensitive drums 2Y, 2M, and 2C (downward in the drawing), and the intermediate transfer belt 8 is moved to the color photosensitive drums 2Y, 2M, and 2C. Separated from 2C.

  Next, when the intermediate transfer belt 8 is brought into contact with the color photosensitive drums 2Y, 2M, and 2C, the eccentric cam 26 is rotated 180 degrees from the state shown in FIG. Then, the abutting portion 25a of the moving member 25 and the lower end 23b of each rotating member 23 are pushed by the urging force of the coil spring 24 and moved to the left side of the figure. Rotate around. As the rotating member 23 rotates, each primary transfer roller 11 moves in a direction approaching the color photosensitive drums 2Y, 2M, and 2C (upward in the drawing), and the intermediate transfer belt 8 is moved. Are in contact with the color photosensitive drums 2Y, 2M, and 2C (see FIG. 3).

FIG. 5 is an enlarged view of one of the rotating members 23, and is a diagram illustrating a configuration according to the first embodiment of the present invention.
As shown in FIG. 5, the lower end 23 b side of the rotating member 23 is bent, and the rotating member 23 is a first contact disposed on the surface facing the coil spring 24 at different angles. It has a contact surface X and a second contact surface Y. In the present embodiment, the angle β formed by the first contact surface X and the second contact surface Y is a rotation by which the rotation member 23 rotates between the first position and the second position. It is set to be the same as the angle α. FIG. 5 shows a state where the rotation angle α and the angle β between the contact surfaces X and Y are set to 15 ° as an example.

  Further, in the present embodiment, the first contact surface X is in a state in which the rotating member 23 is disposed at the first position indicated by a solid line in the drawing (the primary transfer roller 11 passes through the intermediate transfer belt 8 and the photosensitive drum). 2 is in contact with the urging direction Z of the coil spring 24. On the other hand, the second contact surface Y is a state in which the rotating member 23 is disposed at the second position indicated by a two-dot chain line in the figure (a state where the primary transfer roller 11 is separated from the photosensitive drum 2). Thus, the coil spring 24 is disposed so as to be orthogonal to the urging direction Z of the coil spring 24.

FIG. 6 is a diagram illustrating a state in which the rotating member 23 is disposed at the first position. FIG. 7 is a view showing a state in which the rotating member 23 is disposed at the second position.
As shown in FIG. 6, when the rotating member 23 is disposed at the first position, the coil spring 24 contacts the first contact surface X of the rotating member 23. On the other hand, as shown in FIG. 7, when the rotating member 23 is disposed at the second position, the coil spring 24 comes into contact with the second contact surface Y of the rotating member 23. As described above, when the position is changed by rotating the rotating member 23, the coil spring 24 comes into contact with different surfaces of the rotating member 23.

FIG. 8 is an enlarged view showing the configuration of the rotating member 23 according to the second embodiment.
In this embodiment, the convex part 28 inserted in the coil spring 24 is provided in the surface which the coil spring 24 of the rotation member 23 opposes. As shown in FIG. 9, the convex part 28 which concerns on this embodiment is formed in the cone shape. Thus, since the convex part 28 is formed in the taper shape which becomes thin toward the front-end | tip, it becomes easy to insert the convex part 28 in the coil spring 24, and an assembly property improves. For example, when the convex portion 28 is injection-molded with a resin material, the convex portion 28 can be formed in a tapered shape by increasing the draft from the mold.

  The convex portion 28 and the rotating member 23 may be integrally formed. When these are configured integrally, the number of parts is reduced, so that the cost can be reduced. Moreover, you may comprise the convex part 28 and the rotation member 23 by another body. In the case where these are configured separately, by attaching the convex portion 28 to the rotating member 23 via a double-sided adhesive tape, the mounting operation can be easily performed, and an inexpensive and space-saving device can be obtained. Further, by making these separate, the convex portion 28 and the rotating member 23 can be molded from different materials. For example, when it is desired to improve the strength and wear resistance of the convex portion 28 with respect to the contact with the coil spring 24 and to suppress the wear of the convex portion 28 due to the contact with the coil spring 24, a metal material may be used only for the convex portion 28. it can. As this metal material, a SUS material is desirable. Further, when it is desired to ensure the slidability of the convex portion 28 with respect to the coil spring 24, the convex portion 28 is made of a resin material having slidability, and the rotating member 23 is made of a material that is inexpensive and has good moldability. Is also possible.

  Further, in the cross section obtained by cutting the convex portion 28 along a plane orthogonal to the rotational axis Q of the rotating member 23 (a plane parallel to the paper surface of FIG. 8), the angle γ formed by both side surfaces of the convex portion 28 is 23 is set to be the same as the rotation angle α that rotates between the first position and the second position. In addition, in FIG. 8, the state set to 15 degrees is shown as an example of rotation angle (alpha) and angle (gamma) which the side surface of the convex part 28 comprises.

  The configuration of the second embodiment of the rotating member 23 has been described above. However, the configuration other than the above-described configuration is the same as that of the embodiment shown in FIGS.

FIG. 10 is an enlarged view showing the configuration of the third embodiment of the rotating member 23.
In the present embodiment, the bent portion U between the first contact surface X and the second contact surface Y of the rotating member 23 is formed in a curved surface shape. Other than that, it is comprised similarly to the said embodiment.

  As described above, in the conventional configuration, since the coil spring is always in contact with the same surface of the rotating member, the contact surface of the rotating member is inclined with respect to the coil spring with the rotation. (See FIGS. 18 and 19). On the other hand, in the configuration according to the embodiment of the present invention, the rotating member 23 has the first contact surface X and the second contact surface Y arranged at different angles. When the position is changed by rotating the rotating member 23, the coil spring 24 can be brought into contact with a different surface (the first contact surface X or the second contact surface Y) (FIG. 6 and FIG. 6). (See FIG. 7). Thereby, the inclination of each contact surface X and Y with respect to the coil spring 24 can be reduced as compared with the prior art. As a result, the bending of the coil spring 24 accompanying the rotation of the rotating member 23 can be suppressed, and the generation of noise due to the coil spring 24 coming into contact with the peripheral member can be prevented. Further, by suppressing the bending of the coil spring 24 and stabilizing the posture, there is no possibility of image defects caused by the coil spring 24 being caught by the peripheral members, and the reliability is improved.

  Further, as in the above-described embodiment, the angle β formed by the first contact surface X and the second contact surface Y is set to the same angle as the rotation angle α of the rotation member 23, thereby enabling rotation. Even when the moving member 23 is disposed at either the first position or the second position, the inclination of the contact surfaces X and Y with respect to the coil spring 24 can be reduced. Further, when both the first contact surface X and the second contact surface Y are in contact with the coil spring 24 and are arranged so as to be orthogonal to the biasing direction Z, the coil The bending of the spring 24 can be eliminated. As a result, problems such as abnormal noise and image defects due to the bending of the coil spring 24 can be suppressed to a higher degree, and an image forming apparatus with higher reliability can be provided.

  Moreover, in 2nd Embodiment shown in FIG. 8, since the convex part 28 is provided in the rotation member 23, the edge part of the coil spring 24 can be hold | maintained by the convex part 28, and the rotation member 23 of FIG. It is possible to prevent displacement and detachment of the coil spring 24 from the contact surface. Further, the presence of the convex portion 28 has an advantage that the rotating member 23 and the coil spring 24 can be easily assembled at the time of manufacture. Furthermore, by setting the angle γ formed by the both side surfaces of the convex portion 28 provided on the rotating member 23 to the same angle as the rotating angle α of the rotating member 23, when the rotating member 23 rotates, It is possible to avoid pressing of the inner peripheral surface of the coil spring 24 by the convex portion 28. Thereby, it can prevent that the coil spring 24 curves by the press of the convex part 28, and the generation | occurrence | production of the noise by the coil spring 24 contacting a peripheral member like the above, or the coil spring 24 is caught by a peripheral member. It is possible to prevent image defects and the like caused by this.

  Further, when the bent portion U between the first contact surface X and the second contact surface Y is formed in a curved surface as in the third embodiment shown in FIG. Since it can be smoothly moved between the first contact surface X and the second contact surface Y, the rotation member 23 can be rotated smoothly.

FIG. 11 and FIG. 12 show the configuration of the fourth embodiment of the rotating member 23.
As shown in FIG. 11, also in this embodiment, the lower end 23b side of the rotating member 23 is bent and formed on the surface facing the coil spring 24 at different angles. A contact surface X and a second contact surface Y are provided. Furthermore, in this embodiment, the contact member 32 having the third contact surface V is provided across the first contact surface X and the second contact surface Y. Specifically, a rectangular notch 33 is formed in the region of the first contact surface X and the second contact surface Y, and a rectangular contact member 32 is disposed in the notch 33. ing. The contact member 32 is rotatably supported by a rotation shaft 34 provided between the first contact surface X and the second contact surface Y (or a bent portion). The rotating shaft 34 of the contact member 32 is disposed so as to be parallel to a rotating shaft (not shown) of the rotating member 23.

  As shown in FIG. 12, the rotation shaft 34 of the contact member 32 is provided between the first contact surface X and the second contact surface Y (or the bent portion) of the rotation member 23. It is directly received and supported by a U-shaped groove-shaped receiving portion 35. As described above, by providing the receiving portion 35 that directly receives the rotation shaft 34 of the contact member 32, the contact member 32 can be supported without adding new components, and the number of components can be reduced. Further, in the present embodiment, the opening of the receiving portion 35 for inserting the rotating shaft 34 into the receiving portion 35 is disposed so as to open on the surface side where the coil spring 24 contacts the rotating member 23. ing. Thus, by arranging the opening of the receiving portion 35, the contact member 32 can be easily attached to the receiving portion 35. Further, after the attachment, the contact member 32 is urged by the coil spring 24 in the direction opposite to the opening of the receiving portion 35, so that the contact member 32 can be prevented from falling off the receiving portion 35.

  As described above, in this embodiment, the contact member 32 is accommodated in the notch 33, so that the size of the rotating member 23 does not increase even if the contact member 32 is provided. Can be planned. However, the notch 33 must be formed larger than the contact member 32 so as not to interfere with the contact member 32 and prevent the rotation. On the other hand, if the notch 33 is formed too large, the rotating member 23 becomes large, resulting in an increase in the size of the apparatus main body. Therefore, care must be taken in setting the size. Specifically, in FIG. 11, the lengths from the rotation center line of the contact member 32 to both end portions of the notch 33 in the direction orthogonal thereto are denoted as K1 and K2, and the rotation center line of the contact member 32 When the length from the contact member 32 to both ends in the direction orthogonal to L1 and L2 is L1, it is desirable that L1 <K1 <L1 + 5 [mm] and L2 <K2 <L2 + 5 [mm]. . In other words, it is preferable that a gap of less than 5 mm is provided between both end portions of the contact member 32 in the direction orthogonal to the rotation axis and the notch portion 33 facing them. In this way, by setting the size of the notch 33, it is possible to prevent the contact member 32 and the notch 33 from interfering with each other to ensure smooth rotation of the contact member 32 and to increase the size of the apparatus. Can also be prevented.

  As shown in FIG. 11, the entire length L3 of the third contact surface V in the direction orthogonal to the rotation axis of the contact member 32 is formed to be larger than the outer diameter D1 of the coil spring 24. It is desirable. Thereby, a large contact surface of the coil spring 24 can be ensured, and the posture of the coil spring 24 can be further stabilized.

  The configuration of the fourth embodiment of the present invention has been described above, but the configuration other than the above-described configuration is the same as the configuration of the first embodiment of the present invention shown in FIG.

Hereinafter, the operation of the fourth embodiment will be described with reference to FIGS. 13 and 14.
First, as shown in FIG. 13, when the rotating member 23 is disposed at the first position (the state shown in FIG. 6), the coil spring 24 is connected to the first contact surface X of the rotating member 23. It is in a state of being in contact with the third contact surface V. Then, as shown in FIG. 14, when the rotating member 23 is rotated to reach the second position (the state shown in FIG. 7), the coil spring 24 has the first contact surface X. And come into contact with the second contact surface Y. Further, since the contact member 32 is configured to be rotatable with respect to the rotation member 23, the third contact surface V of the contact member 32 and the coil spring even when the rotation member 23 rotates. 24 is maintained in a state orthogonal to each other or in a state close thereto. For this reason, even if the rotation member 23 rotates, the coil spring 24 is held in contact with the third contact surface V. Thereafter, when the rotating member 23 is disposed again at the first position shown in FIG. 13, the coil spring 24 is held in contact with the third contact surface V while being held in the second contact. It is separated from the surface Y and contacts the first contact surface X. Thereafter, the same operation is repeated each time the rotating member 23 rotates.

  Thus, in this embodiment, since the contact member 32 is configured to be rotatable with respect to the rotation member 23, the rotation member 23 rotates between the first position and the second position. The coil spring 24 always has the third contact surface even when the contact surface of the coil spring 24 switches between the first contact surface X and the second contact surface Y as it moves. It is held in contact with V.

FIG. 15 is an enlarged view showing the configuration of the fifth embodiment of the rotating member 23.
As in the fourth embodiment, the rotating member 23 according to the present embodiment is provided with a rotatable contact member 32 having a third contact surface V. Furthermore, in the present embodiment, a convex portion 28 that is inserted into the coil spring 24 is provided on the third contact surface V. Thus, similarly to the embodiment shown in FIG. 8, the end portion of the coil spring 24 can be held by the convex portion 28, and the displacement and detachment of the coil spring 24 from the contact surface of the rotating member 23 are prevented. It becomes possible. Further, since the convex portion 28 is provided, the rotating member 23 and the coil spring 24 can be easily assembled at the time of manufacture. Furthermore, as shown in FIG. 15, the convex portion 28 is formed into a tapered shape that becomes narrower toward the tip, so that the convex portion 28 can be easily inserted into the coil spring 24. Further, similarly to the above, the convex portion 28 may be formed in a tapered shape by giving a large draft to the mold for molding the convex portion 28 with resin.

FIG. 16 is an enlarged view showing the configuration of the rotating member 23 according to the sixth embodiment.
The embodiment shown in FIG. 16 differs from the embodiment shown in FIG. 15 only in the shape of the convex portion 28. In FIG. 16, the outer diameter D <b> 3 of the convex portion 28 is formed larger than the inner diameter D <b> 2 of the coil spring 24, and the convex portion 28 is press-fitted into the coil spring 24. In this way, by press-fitting the convex portion 28 into the coil spring 24, it is possible to more stably suppress the bending of the coil spring 24 accompanying the rotation of the rotation member 23. Further, at the time of manufacture, the projecting portion 28 is press-fitted into the coil spring 24, and the contact member 32 and the coil spring 24 are set as subassemblies, so that they can be assembled integrally with the rotating member 23, and productivity is improved. improves. Moreover, in this embodiment, even if the rotation member 23 rotates, the third contact surface V and the coil spring 24 are maintained in a state of being orthogonal to each other or in a state close thereto. Even if the coil spring 24 is integrally attached, problems such as bending of the coil spring 24 do not occur.

  In addition, the convex part 28 in embodiment shown in FIG.15 and FIG.16 may be comprised integrally with the contact member 32, and can also be comprised separately. When the convex portion 28 and the contact member 32 are integrally formed, the number of parts is reduced, and thus the cost can be reduced. Moreover, when the convex part 28 and the contact member 32 are comprised separately, by attaching the convex part 28 with respect to the contact member 32 via a double-sided adhesive tape, attachment work can be performed easily and at low cost. It becomes a space-saving device. Moreover, by making these separate, it becomes possible to mold the convex portion 28 and the rotating member 23 or the contact member 32 with different materials. For example, when it is desired to improve the strength and wear resistance of the convex portion 28 against the contact of the coil spring 24, a metal material can be used only for the convex portion 28. In this case, a SUS material is desirable as the metal material. When it is desired to ensure the slidability of the convex portion 28 with respect to the coil spring 24, the convex portion 28 is made of a resin material having slidability, and the rotating member 23 and the contact member 32 are inexpensive and have good moldability. It can also be made of a material.

  As described above, also in the embodiment having the third contact surface V shown in FIGS. 11 to 16, the coil spring 24 is moved to a different surface (first contact) as the rotation member 23 rotates. Since the contact surface X or the second contact surface Y) can be brought into contact with each other, the inclination of the contact surfaces X and Y with respect to the coil spring 24 can be reduced as compared with the conventional case. Thereby, bending of the coil spring 24 accompanying rotation of the rotation member 23 can be suppressed, and generation | occurrence | production of the noise by the coil spring 24 contacting a peripheral member can be prevented. Further, by suppressing the bending of the coil spring 24 and stabilizing the posture, there is no possibility of image defects caused by the coil spring 24 being caught by the peripheral members, and the reliability is improved.

  Furthermore, in the embodiment shown in FIGS. 11 to 16, since the rotatable contact member 32 having the third contact surface V is provided, the coil is rotated as the rotating member 23 rotates. Even when the contact surface of the spring 24 is switched between the first contact surface X and the second contact surface Y, the coil spring 24 is always in contact with the third contact surface V. Held in. Thereby, the receiving area with respect to the coil spring 24 can be ensured, and the posture of the coil spring 24 can be further stabilized. In addition, when the coil spring 24 is used as a power feeding path or a ground path, it is possible to secure stable conduction by securing a receiving area for the coil spring 24 and stabilizing the posture of the coil spring 24. .

  The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention. For example, in the above-described embodiment of the present invention, only the color transfer roller 11 is configured to be contactable / separable, but all the transfer rollers 11 including black may be configured to be contactable / separable. .

  Further, the image forming apparatus shown in FIG. 17 includes a plurality of photosensitive drums 2, a paper feed tray 15 containing recording paper P, and a transport belt that carries and transports the recording paper P supplied from the paper feed tray 15. 30 and a direct transfer type image forming apparatus provided with a plurality of transfer rollers 31 as transfer members for sequentially transferring the images on the photosensitive drums 2 to the recording paper P on the conveying belt 30. The configuration of the present invention is applied to such a direct transfer type image forming apparatus so that any or all of the plurality of transfer rollers 31 are brought into contact with and separated from the photosensitive drum 2. It is also possible to do. Note that a transfer member other than a roller shape (such as a blade shape or a brush shape) may be applied to the transfer member that contacts or separates from the conveyance belt or the intermediate transfer belt. The configuration of the present invention can also be applied to other copiers, printers, facsimiles, or multifunction peripherals thereof.

2 Photosensitive drum (image carrier)
8 Intermediate transfer belt (belt member)
11 Primary transfer roller (belt support member)
23 Rotating member 24 Coil spring (biasing member)
25 Moving member 28 Protruding portion 30 Conveying belt (belt member)
31 Transfer roller (belt support member)
32 Contact member 33 Notch portion 34 Rotating shaft 35 Receiving portion D1 Coil spring outer diameter D2 Coil spring inner diameter D3 Convex outer diameter K1 From the pivot center line of the contact member to one end of the notch Length K2 Length from the rotation center line of the contact member to the other end of the notch L1 Length from the rotation center line of the contact member to one end of the contact member L2 Rotation of the contact member Length from the center line to the other end of the abutting member L3 Overall length of the third abutting surface V Third abutting surface X First abutting surface Y Second abutting surface Z Biasing Direction α Rotation angle β Angle formed by the first contact surface and the second contact surface γ Angle formed by both side surfaces of the convex portion

JP 2007-78754 A JP 2008-216969A

Claims (18)

A belt member, a belt support member that supports the belt member, a rotation member configured to be rotatable between a first position and a second position to move the belt support member; A belt device including a biasing member that abuts on the rotation member and biases the rotation member to the first position;
The rotating member has a first abutting surface against which the urging member abuts when disposed at the first position, and the urging member when the urging member is disposed at the second position. A belt device having a second abutting surface in contact therewith.   The angle formed between the first contact surface and the second contact surface is the same as the rotation angle at which the rotating member rotates between the first position and the second position. The belt device according to claim 1, which is set as follows.   Both the first contact surface and the second contact surface are disposed so as to be orthogonal to the urging direction of the urging member in a state of being in contact with the urging member. The belt device according to claim 1 or 2.   4. The belt device according to claim 1, wherein a surface of the rotating member on which the urging member abuts is bent to form the first abutting surface and the second abutting surface. 5.   The belt device according to claim 4, wherein a bent portion between the first contact surface and the second contact surface is formed in a curved surface shape.   The belt device according to any one of claims 1 to 5, wherein the biasing member is configured by a coil spring, and a convex portion that is inserted into the coil spring and holds the coil spring is provided on the rotating member. .   In a cross section obtained by cutting the convex portion along a plane orthogonal to the rotational axis of the rotating member, an angle formed by both side surfaces of the convex portion is defined by the first position and the second position. The belt device according to claim 6, wherein the belt device is set to the same angle as a rotation angle that rotates between the two.   A rotating shaft that is parallel to the rotating shaft of the rotating member, and has a contacting member having a third contacting surface disposed across the first contacting surface and the second contacting surface. The belt device according to any one of claims 1 to 7, wherein the belt device is provided so as to be rotatable around the center.   The third contact surface is provided with a convex portion that is inserted into the coil spring as the urging member and holds the coil spring, and the outer diameter of the convex portion is larger than the inner diameter of the coil spring. The belt device according to claim 8, wherein the convex portion is configured to be press-fitted into the coil spring.   The belt according to claim 8 or 9, wherein a length of the third contact surface in a direction orthogonal to the rotation axis of the contact member is formed to be larger than an outer diameter of a coil spring as the biasing member. apparatus.   The belt device according to any one of claims 8 to 10, wherein the rotation shaft of the contact member is disposed at a position between the first contact surface and the second contact surface.   The belt device according to any one of claims 8 to 11, wherein the rotating member is provided with a notch portion formed to be larger than the contact member, and the contact member is disposed in the notch portion. .   The belt device according to claim 12, wherein a gap of less than 5 mm is provided between both end portions of the contact member in a direction orthogonal to the rotation axis and the notch portions facing each other.   The belt device according to any one of claims 8 to 13, wherein a receiving portion that directly receives and supports the rotation shaft of the contact member is provided on the rotation member.   The receiving portion has an opening for inserting the rotating shaft of the abutting member, and the opening is arranged so that the biasing member opens on the surface side where the urging member contacts the rotating member. The belt device according to claim 14.   The belt member is an intermediate transfer belt to which an image on the image carrier is transferred, and the belt support member is a transfer member for transferring the image on the image carrier onto the intermediate transfer belt, The belt device according to any one of claims 1 to 15, wherein the transfer member is configured to be brought into contact with and separated from the image carrier by the rotating member.   The belt member is a conveyance belt that carries and conveys a sheet-like recording medium, and the belt support member is a transfer member that transfers an image on the image carrier to a recording medium on the conveyance belt. The belt device according to claim 1, wherein the transfer member is configured to be brought into contact with and separated from the image carrier by the rotating member.   An image forming apparatus comprising the belt device according to claim 1.

Images