Gap adjustment mechanism and image forming apparatus

Abstract

To prevent the interval between a rotation shaft and an opposing member adjusted by an interval adjustment mechanism from being changed by an external force such as an impact during distribution.SOLUTION: In an image forming apparatus 100, an interval adjustment mechanism 10 for adjusting the interval between a rotation shaft 1 of a rotating body 172 and an opposing member 4 arranged opposite to the rotation shaft 1, has an urging member 5, a regulation member 2 that regulates the interval, a force imparting member 3 including a force imparting unit 31 that applies, to the regulation member 2, a force by which the regulation member 2 moves, and a position regulation unit 36 that is elastically deformable and regulates the position of the force imparting member 3. The position regulation unit 36 regulates the position of the force imparting member 3 in a predetermined rotation direction of the rotating body 172 when the rotating body 172 stops rotating, and when the force imparting member 3 rotates in the predetermined rotation direction and the regulation member 2 moves from a first position to a second position, is elastically deformed along with the rotation of the rotating body 172 in a period from when the rotation of the rotating body 172 starts until when the movement of the regulation member 2 from the first position to the second position starts.SELECTED DRAWING: Figure 14

Description

[Technical Field]

[0001] The present invention relates to a gap adjustment mechanism in an image forming apparatus such as a copying machine, printer, facsimile machine, or multifunction machine that uses an electrophotographic or electrostatic recording method, or a multifunction machine that has multiple functions of these, and to an image forming apparatus equipped with the same. [Background technology]

[0002] Conventional image forming apparatuses using electrophotography or the like include direct transfer apparatuses in which a toner image formed on an image carrier is directly transferred to a transfer material such as paper, and intermediate transfer apparatuses in which a toner image formed on an image carrier is transferred to a transfer material via an intermediate transfer belt. Direct transfer image forming apparatuses include a transfer member that contacts the image carrier to form a transfer nip, and the toner image on the image carrier is transferred onto the transfer material passing through the transfer nip. Intermediate transfer image forming apparatuses include a primary transfer member that contacts the intermediate transfer belt with the image carrier to form a primary transfer nip, and the toner image on the image carrier is primarily transferred onto the intermediate transfer belt at the primary transfer nip. A secondary transfer member that contacts the tension roller of the intermediate transfer belt via the intermediate transfer belt to form a secondary transfer nip is also provided, and the toner image on the intermediate transfer belt is secondarily transferred onto the transfer material passing through the secondary transfer nip. Rotatable rollers or pad members are used as transfer members (transfer members, primary transfer members, secondary transfer members), and elastic materials are often used to ensure a wide transfer nip (transfer nip, primary transfer nip, secondary transfer nip).

[0003] The transfer nip is formed by the image carrier or intermediate transfer belt and the transfer member being pressed against each other. If the transfer member is left in contact with the image carrier or the like for a long period of time during transportation, such as during shipping of the image forming apparatus, the elastic body constituting the transfer member may undergo plastic deformation due to the effects of heat. If the elastic body constituting the transfer member undergoes plastic deformation, the transfer nip may not be sufficiently contacted, potentially resulting in transfer failure. Furthermore, in an intermediate transfer image forming apparatus, the plastic deformation of the intermediate transfer belt caused by the pressure of the transfer member can cause unevenness on the surface of the intermediate transfer belt, potentially resulting in transfer failure.

[0004] In response to this, Patent Document 1 discloses a gap adjustment mechanism that is configured, for example, to ship an image forming apparatus with a secondary transfer member spaced apart from an intermediate transfer belt, and automatically bring the secondary transfer member into contact with the intermediate transfer belt in conjunction with the operation of the image forming apparatus. In the gap adjustment mechanism described in Patent Document 1, a regulating member that regulates the gap between the rotating shaft and an opposing member is moved in the axial direction of the rotating shaft in conjunction with the rotational movement of the rotating shaft, thereby changing the gap between the rotating shaft and the opposing member. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-114649 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in a configuration in which the regulating member that regulates the gap between the rotating shaft and the opposing member moves in conjunction with the rotation of the rotating shaft as described above, there is a possibility that the regulating member may move accidentally if it is subjected to a shipping shock. This could result in, for example, the intermediate transfer belt and the secondary transfer member losing their spaced-apart state and coming into contact with each other. Therefore, it may be necessary to use a more extensive packaging method to reduce shipping shock so that the spaced-apart state can be maintained even during anticipated shipping conditions of the image forming apparatus.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to prevent the gap between the rotating shaft and the opposing member, which is adjusted by the gap adjustment mechanism, from being changed by an external force such as an impact during transportation. [Means for solving the problem]

[0008] The above object is achieved by the gap adjustment mechanism and image forming apparatus according to the present invention. In summary, according to one aspect of the present invention, in an image forming apparatus, a gap adjustment mechanism for adjusting a gap between a rotation shaft of a rotating body and an opposing member disposed opposite the rotation shaft includes: a biasing member for biasing the opposing member toward the rotation shaft; a restricting member for restricting the gap, the restricting member being movably attached to the rotation shaft; a force applying member attached to the rotation shaft rotatably in conjunction with rotation of the rotating body in a predetermined rotation direction, the force applying member having a force applying portion that applies a force to the restricting member to move the restricting member; and an elastically deformable position restricting portion for restricting the position of the force applying member, the restricting member being a force receiving portion that receives a force from the force applying member that rotates in conjunction with rotation of the rotating body in the predetermined rotation direction, the force receiving portion receiving a force including a component force acting in the rotation axis direction of the rotating body from the force applying portion due to relative movement between the restricting member and the force applying member. and is movable from a first position, at which the force applying member acts on the biasing force of the biasing member so that the gap becomes a predetermined gap, to a second position in the rotation axis direction that is different from the first position and at which the manner in which the biasing force is applied changes relative to the first position, by rotation of the force applying member in the predetermined rotation direction; and the position regulating unit regulates the position of the force applying member in the predetermined rotation direction when rotation of the rotating body stops, and is configured to be elastically deformed in conjunction with the rotation of the rotating body in the predetermined rotation direction when the force applying member rotates in the predetermined rotation direction in conjunction with the rotation of the rotating body in the predetermined rotation direction and the regulating member moves from the first position to the second position, during the period from when the rotating body starts to rotate in the predetermined rotation direction to when the regulating member starts to move from the first position to the second position.

[0009] According to another aspect of the present invention, there is provided an image forming apparatus comprising a rotating body having a rotating shaft, an opposing member arranged opposite the rotating shaft, and the above-mentioned gap adjustment mechanism of the present invention. [Effects of the Invention]

[0010] According to the present invention, it is possible to prevent the gap between the rotating shaft and the opposing member, which is adjusted by the gap adjustment mechanism, from being changed by an external force such as an impact during logistics. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic perspective view of an image forming apparatus. [Figure 2] FIG. 1 is a schematic cross-sectional view of an image forming apparatus. [Figure 3] FIG. 2 is a schematic cross-sectional view of an image forming unit. [Figure 4] FIG. 4 is a side view illustrating a support structure for a drive roller and a secondary transfer roller. [Figure 5] FIG. 10 is a perspective view illustrating components of a gap adjustment mechanism of a comparative example. [Figure 6] 10A and 10B are a side view and a cross-sectional view for explaining the operation of the gap adjustment mechanism of the comparative example. [Figure 7] 10A and 10B are a side view and a cross-sectional view for explaining the operation of the gap adjustment mechanism of the comparative example. [Figure 8] 10A and 10B are a side view and a cross-sectional view for explaining the operation of the gap adjustment mechanism of the comparative example. [Figure 9] 10A and 10B are a side view and a cross-sectional view for explaining the influence of a transport shock on a gap adjustment mechanism of a comparative example. [Figure 10] FIG. 2 is a perspective view of a force applying member that constitutes the gap adjusting mechanism of the first embodiment. [Figure 11] 4A and 4B are a side view and a cross-sectional view for explaining the operation of the gap adjusting mechanism of the first embodiment. [Figure 12] 4A and 4B are a side view and a cross-sectional view for explaining the operation of the gap adjusting mechanism of the first embodiment. [Figure 13] 4A and 4B are a side view and a cross-sectional view for explaining the operation of the gap adjusting mechanism of the first embodiment. [Figure 14] 4A and 4B are side views and a cross-sectional view for explaining the operation of the gap adjustment mechanism of the first embodiment against a transport shock. [Figure 15] FIG. 14(c) is an enlarged view of a part of FIG. [Figure 16] FIG. 10 is a perspective view showing a comparison of the force applying members of a comparative example and Example 1. [Figure 17] 10A and 10B are a side view and a cross-sectional view for explaining a gap adjusting mechanism of a second embodiment. [Figure 18] FIG. 11 is a perspective view of a regulating member and a force applying member that constitute the gap adjusting mechanism of the third embodiment. [Figure 19] 11A and 11B are a side view and a cross-sectional view for explaining the operation of the gap adjusting mechanism of the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] The gap adjustment mechanism and image forming apparatus according to the present invention will be described in detail below by way of example with reference to the drawings. The dimensions, materials, shapes, and relative positions of the components described in the following examples may be changed as appropriate depending on the configuration and various conditions of the apparatus to which the present invention is applied. In other words, the scope of the present invention is not limited to the following examples.

[0013] [Example 1] 1. Configuration of image forming device Fig. 1 is a schematic perspective view of the appearance of an image forming apparatus 100 of this embodiment. Fig. 2 is a schematic cross-sectional view (showing a cross section perpendicular to the direction of the rotation axis of a photosensitive drum 101, which will be described later) showing the internal configuration of the image forming apparatus 100 of this embodiment.

[0014] The image forming apparatus 100 of this embodiment is a tandem printer employing an intermediate transfer system capable of forming full-color images using electrophotography. The image forming apparatus 100 includes four image forming units PY, PM, PC, and PK, which form images using toner of each color: yellow (Y), magenta (M), cyan (C), and black (K). The image forming apparatus 100 also employs a process cartridge system, with each image forming unit PY, PM, PC, and PK being equipped with process cartridges 108Y, 108M, 108C, and 108K, respectively, that are detachably mounted in a main body 110 of the image forming apparatus 100. The process cartridges 108Y, 108M, 108C, and 108K can be removed from and installed in the main body 110 with a door 111 provided in the main body 110 open. In this embodiment, the apparatus main body 110 is the image forming apparatus 100 excluding the process cartridges 108Y, 108M, 108C, and 108K.

[0015] The four image forming units PY, PM, PC, and PK are arranged in a row at regular intervals. In this embodiment, the configurations of the image forming units PY, PM, PC, and PK are essentially the same, except that the color of toner contained in the developing device 104, which will be described later, is different. Elements having the same or corresponding functions or configurations provided for each color may be described collectively by omitting the Y, M, C, or K at the end of the reference numeral indicating that the element is for one of the colors. Figure 3 is a schematic cross-sectional view showing one representative image forming unit P.

[0016] Here, with regard to the image forming apparatus 100 and its components, the right side of the page in FIG. 2 (the side where the opening / closing door 111 is provided) is referred to as the "front (front) side," and the left side (opposite the front side) is referred to as the "rear (back) side." When viewing the image forming apparatus 100 from the front side, the right side is referred to as the "drive side," and the left side is referred to as the "non-drive side." The drive side is the end side to which driving force is input in the rotational axis direction of the photosensitive drum 101 and the drive roller 172, which will be described later. The linear direction connecting the drive side and the non-drive side is approximately parallel to the rotational axis direction of the photosensitive drum 101 and the drive roller 172. The direction from the rear side to the front side of the apparatus body 110 is referred to as the "X direction," the direction from the non-drive side to the drive side, which is perpendicular to the X direction, is referred to as the "Y direction," and the direction from the bottom to the top of the apparatus body 110, which is perpendicular to the X direction and the Y direction, is referred to as the "Z direction." Furthermore, the direction opposite to the X direction (or +X direction), the direction opposite to the Y direction (or +Y direction), and the direction opposite to the Z direction (or +Z direction) are also referred to as the "-X direction," the "-Y direction," and the "-Z direction," respectively. It is assumed that image forming apparatus 100 will be used while being disposed so that the X direction and the Y direction are both approximately horizontal. Furthermore, with respect to image forming apparatus 100 and its elements, the up and down direction refers to the up and down in the direction of gravity (vertical direction), but does not mean only directly above or directly below, but also includes the above and below of a horizontal plane passing through the element or position of interest.

[0017] The four image forming stations PY, PM, PC, and PK are arranged substantially horizontally on the bottom surface of the apparatus main body 110. The image forming stations P (PY, PM, PC, PK) are configured with electrophotographic process mechanisms such as photosensitive drums 101 (101Y, 101M, 101C, 101K), charging rollers 102 (102Y, 102M, 102C, 102K), exposure devices 103, developing devices 104 (104Y, 104M, 104C, 104K), and cleaning devices 105 (105Y, 105M, 105C, 105K). The photosensitive drum 101 is a movable (rotatable) drum-type (cylindrical) photosensitive member (electrophotographic photosensitive member) that serves as an image carrier. In this embodiment, the exposure device 103 is configured as a single unit that exposes the photosensitive drums 101Y, 101M, 101C, and 101K of the four image forming stations PY, PM, PC, and PK. However, an independent exposure device 103 may be provided for each image forming station P. In each image forming station P, the photosensitive drum 101, charging roller 102, developing device 104, and cleaning device 105 constitute a process cartridge 108. A cartridge drive transmission unit (not shown) provided in the apparatus main body 110 transmits a rotational driving force to each process cartridge 108 from a cartridge drive unit (not shown) provided in the apparatus main body 110. As a result, the photosensitive drum 101 of each process cartridge 108 is driven to rotate in the direction of arrow R1 (counterclockwise) in FIGS. 2 and 3. The exposure device 103 is provided above each process cartridge 108. The operation of each image forming station P will be described later.

[0018] An intermediate transfer unit 107 is provided below each process cartridge 108. The intermediate transfer unit 107 includes an intermediate transfer belt 171, four primary transfer rollers 106Y, 106M, 106C, and 106K, tension rollers 172, 173, and 174 for supporting the intermediate transfer belt 171, a toner charging brush 175, and a frame 176. The intermediate transfer belt 171 is an intermediate transfer member formed of a movable (rotatable) endless belt. The intermediate transfer belt 171 is stretched over and tensioned by a predetermined tension between a drive roller 172, a tension roller 17, and an assist roller 174, which serve as multiple tension rollers. A driving force is transmitted from a belt drive unit (not shown) provided in the apparatus main body 110 to the drive roller 172, causing it to rotate clockwise in FIG. 2. As a result, a driving force is transmitted from the drive roller 172 to the intermediate transfer belt 171, causing it to rotate (circularly move) in the direction of arrow R2 (clockwise direction) in FIGS. 2 and 3. The tension roller 173 applies a predetermined tension to the intermediate transfer belt 171. The assist roller 174 forms the surface of the intermediate transfer belt 171 that enters the secondary transfer portion N2, which will be described later. The toner charging brush 175 charges the toner on the intermediate transfer belt 171 so that the toner can be collected by the cleaning device 105 of the process cartridge 108.

[0019] On the inner circumferential surface side of the intermediate transfer belt 171, primary transfer rollers 106Y, 106M, 106C, and 106K, which are roller-type primary transfer members serving as primary transfer means, are arranged corresponding to the photosensitive drums 101Y, 101M, 101C, and 101K, respectively. The primary transfer rollers 106 extend along the Y direction and contact the inner circumferential surface of the intermediate transfer belt 171. The primary transfer rollers 106 urge (press) the intermediate transfer belt 171 toward the photosensitive drums 101, forming primary transfer portions (primary transfer nips) N1 where the photosensitive drums 101 and the intermediate transfer belt 171 come into contact. In this embodiment, each primary transfer roller 106 is arranged offset from the position of each primary transfer portion N1 where the photosensitive drums 101 and the intermediate transfer belt 171 come into contact. More specifically, in this embodiment, each primary transfer roller 106 is disposed at a position shifted downstream from the position of each primary transfer portion N1 in the movement direction of the intermediate transfer belt 171. Note that each primary transfer roller 106 may also be disposed at a position shifted upstream from the position of each primary transfer portion N1. The tension rollers other than the drive roller 172 and each primary transfer roller 106 are rotated in accordance with the rotation of the intermediate transfer belt 171.

[0020] On the outer circumferential surface side of the intermediate transfer belt 171, a secondary transfer roller 109, which is a roller-type secondary transfer member serving as a secondary transfer means, is disposed at a position facing the drive roller 172 with the intermediate transfer belt 171 interposed therebetween. The secondary transfer roller 109 extends along the Y direction and contacts the outer circumferential surface of the intermediate transfer belt 171. The secondary transfer roller 109 is urged (pressed) toward the drive roller 172 via the intermediate transfer belt 171, forming a secondary transfer portion (secondary transfer nip) N2 where the intermediate transfer belt 171 and the secondary transfer roller 109 come into contact. The drive roller 172 functions as a driving rotor that rotates the intermediate transfer belt 171 and also functions as an opposing electrode for the secondary transfer roller 109. The secondary transfer roller 109 is rotated in accordance with the rotation of the intermediate transfer belt 171.

[0021] A feeding device 120 as a feeding means, a pair of registration rollers 112 as a conveying means, and the like are provided upstream of the secondary transfer portion N2 in the conveying direction of the transfer material S. The feeding device 120 is configured to have a cassette 51 as a transfer material storage portion that stores the transfer material S, a feeding roller 52 as a feeding member that feeds the transfer material S from the cassette 51, and the like. Further, a fixing device 113 as a fixing means, a pair of discharge rollers 114 as a discharge conveying means, and the like are provided downstream of the secondary transfer portion N2 in the movement direction of the transfer material S. Further, a tray 115 as a stacking portion is provided on the top surface of the device main body 110.

[0022] The image forming apparatus 100 is also equipped with a controller (not shown) as a control means for controlling the operation of each part of the image forming apparatus 100, a memory (not shown) as a storage means in which various control information is stored, etc. The controller executes control related to the transport of the transfer material S, control related to the driving of the intermediate transfer belt 171 and each image forming part P, control related to image formation, etc.

[0023] 2. Image formation operation Next, the image forming operation of the image forming apparatus 100 of this embodiment will be described.

[0024] When a controller (not shown) provided in the apparatus main body 110 receives an image signal from an external device (not shown) such as a personal computer, it controls each unit of the image forming apparatus 100 to start an image forming operation. When the image forming operation starts, the photosensitive drum 101, the drive roller 172, etc. start rotating at a predetermined peripheral speed (process speed) by receiving a driving force transmitted from a driving source (not shown) of each drive unit.

[0025] The surface of the rotating photosensitive drum 101 is uniformly charged to the same polarity as the normal charging polarity of the toner (negative polarity in this embodiment) by a charging roller 102, which is a roller-type charging member serving as charging means. The charging roller 102 is disposed in contact with the surface of the photosensitive drum 101 and rotates in accordance with the rotation of the photosensitive drum 101. During charging, a predetermined charging voltage (charging bias) of the same polarity as the normal charging polarity of the toner is applied to the charging roller 102 by a charging power supply (high-voltage power supply) not shown.

[0026] The surface of the charged photosensitive drum 101 is scanned and exposed by an exposure device 103 serving as an exposure means in accordance with image information, and an electrostatic latent image (electrostatic image) is formed on the photosensitive drum 101. The exposure device 103 outputs laser light in accordance with the image information received by a controller. The laser light output from the exposure device 103 passes through an exposure window portion of a process cartridge 108 and is irradiated onto the surface of the photosensitive drum 101. The exposure device 103 scans and exposes each of the photosensitive drums 101Y, 101M, 101C, and 101K in accordance with image information of image components of colors corresponding to each of the image forming portions PY, PM, PC, and PK.

[0027] The electrostatic latent image formed on the photosensitive drum 101 is developed (visualized) by a developing device 104 as a developing means, which supplies toner as a developer, and a toner image (toner image, developer image) corresponding to the image information is formed on the photosensitive drum 101. The developing device 104 is configured to include a developing roller 141 as a developer carrier (developing member), a developing container 142 that contains toner, and the like. The developing device 104 carries toner in the developing container 142 on the developing roller 141, transports it to a position facing the photosensitive drum 101, and supplies toner from the developing roller 141 to the photosensitive drum 101 in accordance with the electrostatic latent image on the photosensitive drum 101. In this embodiment, the developing device 104 uses a non-magnetic one-component developer (toner) as a developer. In this embodiment, the developing roller 141 is brought into contact with the photosensitive drum 101 during development. During development, a predetermined development voltage (development bias) of the same polarity as the normal charging polarity of the toner is applied to the development roller 141 by a development power supply (high-voltage power supply) not shown. In this embodiment, toner charged with the same polarity as the charging polarity of the photosensitive drum 101 (negative in this embodiment) adheres to the exposed portion of the photosensitive drum 101, which has been uniformly charged and then exposed to light to reduce the absolute value of the potential (reverse development method). In this embodiment, the normal charging polarity of the toner, which is the main charging polarity of the toner during development, is negative. The developing devices 104 of the image forming units PY, PM, PC, and PK contain toner of each color: yellow, magenta, cyan, and black, respectively.

[0028] The toner images formed on the photosensitive drums 101 are transferred (primary transfer) by the action of the primary transfer rollers 106 at the primary transfer section N1 onto the rotating intermediate transfer belt 171, which serves as a transfer receiving body. During the primary transfer, a predetermined primary transfer voltage (primary transfer bias) of a polarity opposite to the normal charging polarity of the toner (positive polarity in this embodiment) is applied to the primary transfer rollers 106 by a primary transfer power supply (high-voltage power supply), not shown. For example, when forming a full-color image, the toner images of yellow, magenta, cyan, and black formed on each photosensitive drum 101 are transferred sequentially at each primary transfer section N1 onto the intermediate transfer belt 171 so as to be superimposed on top of each other. As a result, four-color toner images corresponding to the target color image are formed on the intermediate transfer belt 171.

[0029] The toner image formed on the intermediate transfer belt 171 is transferred (secondary transfer) by the action of the secondary transfer roller 109 at the secondary transfer section N2 onto a transfer material S, which is sandwiched and transported between the intermediate transfer belt 171 and the secondary transfer roller 109. During the secondary transfer (when the transfer material S passes through the secondary transfer section N2), a predetermined secondary transfer voltage (secondary transfer bias) of a polarity opposite to the normal charging polarity of the toner is applied to the secondary transfer roller 109 by a secondary transfer power supply (high-voltage power supply) not shown. The drive roller 172 is electrically grounded (connected to ground potential). Note that a secondary transfer voltage of the same polarity as the normal charging polarity of the toner may be applied to an inner roller corresponding to the drive roller 172 in this embodiment, and the outer roller corresponding to the secondary transfer roller 109 in this embodiment may be electrically grounded. The transfer material S (recording material, recording medium, sheet) such as paper or an OHP sheet is stored in a cassette 121. The transfer material S stored in the cassette 121 is fed from the cassette 121 at a predetermined timing by a feed roller 122 or the like. After the transfer material S has been corrected for skew by a registration roller 112, it is transported toward the secondary transfer portion N2 in synchronization with the toner image on the intermediate transfer belt 171.

[0030] The transfer material S onto which the toner image has been transferred at the secondary transfer portion N2 is conveyed to a fixing device 113. The fixing device 113 heats and pressurizes the transfer material S bearing the unfixed toner image, thereby melting (mixing colors) the toner image and fixing it onto the transfer material S. Thereafter, the transfer material S onto which the toner image has been fixed is discharged from the apparatus main body 110 by a pair of discharge rollers 114 or the like, and is stacked on a tray 115.

[0031] Furthermore, toner remaining on the photosensitive drum 101 after the primary transfer (primary transfer residual toner) is removed from the photosensitive drum 101 and collected by a cleaning device 105 serving as a cleaning means. The cleaning device 105 includes a cleaning blade 151 as a cleaning member arranged in contact with the surface of the photosensitive drum 101, and a cleaning container 152 that contains the toner removed from the surface of the photosensitive drum 101. The cleaning device 105 uses the cleaning blade 151 to scrape the primary transfer residual toner from the surface of the rotating photosensitive drum 101 and collects it in a cleaning container 152. Furthermore, deposits such as toner remaining on the intermediate transfer belt 171 after the secondary transfer (secondary transfer residual toner) are charged to a polarity opposite to the normal charging polarity of the toner by a toner charging brush 175 serving as a toner charging means (belt cleaning means). A predetermined toner charging voltage (toner charging bias) of a polarity opposite to the normal charging polarity of the toner is applied to the toner charging brush 175 by a toner charging power supply (high-voltage power supply) not shown. The secondary transfer residual toner charged by the toner charging brush 175 moves onto the photosensitive drum 101 by the action of the primary transfer voltage at the primary transfer portion N1, and is collected by the cleaning device 105. Note that the secondary transfer residual toner moves, for example, onto the yellow photosensitive drum 101Y, which is the most upstream in the rotation direction (surface movement direction) of the intermediate transfer belt 171, and is collected. Note that a belt cleaning device that removes and collects deposits from the intermediate transfer belt 171 using a cleaning member such as a cleaning blade may be provided as the belt cleaning means.

[0032] 3. Support structure for drive roller and secondary transfer roller Next, the supporting structure for the drive roller 172 and the secondary transfer roller 109 will be described.

[0033] FIG. 4 is a side view of the vicinity of the drive roller 172 and the secondary transfer roller 109 as viewed in the -Z direction (illustration of the intermediate transfer belt 171 is omitted). FIG. 4(a) shows a state in which the secondary transfer roller 109 is in contact with the intermediate transfer belt 171 and the drive roller 172 (also simply referred to as the "contact state" here). FIG. 4(b) shows a state in which the secondary transfer roller 109 is spaced apart from the intermediate transfer belt 171 and the drive roller 172 (also simply referred to as the "spaced state" here). During image formation, the secondary transfer roller 109 is in contact with the intermediate transfer belt 171 and the drive roller 172 as shown in FIG. 4(a). When the image forming apparatus 100 is shipped, the secondary transfer roller 109 is spaced apart from the intermediate transfer belt 171 and the drive roller 172 as shown in FIG. 4(b).

[0034] The drive roller 172, which is a rotating body, is driven to rotate clockwise in FIG. 2, rotating the intermediate transfer belt 171. The drive roller 172 is configured with a core and a rubber layer formed of elastic rubber around the core. The drive roller 172 is provided with a rotation shaft 1 at both ends in the rotation axis direction, protruding from a roller portion 172a formed of the core and rubber layer. The rotation shaft 1 of the drive roller 172 is rotatably supported by a bearing portion 177 provided in a frame 176 of the intermediate transfer unit 107. The secondary transfer roller 109 is disposed opposite the drive roller 172 across the intermediate transfer belt 171. The secondary transfer roller 109 is rotated in accordance with the rotation of the intermediate transfer belt 171. The secondary transfer roller 109 is configured with a core and a foam rubber layer formed of elastic conductive foam rubber around the core. The secondary transfer roller 109 is provided with a rotation shaft 109b at both ends in the direction of its rotation axis, protruding from the roller portion 109a. The rotation shaft 109b of the secondary transfer roller 109 is rotatably supported by a secondary transfer bearing 4 serving as a support member. The secondary transfer bearing 4 constitutes an opposing member that faces the rotation shaft 1 of the drive roller 172. The secondary transfer bearing 4 is supported by a secondary transfer frame 116 provided in the device main body 110 so as to be movable (linearly movable) in a direction toward (X direction) and a direction away (-X direction) from the rotation shaft 1 of the drive roller 172. The secondary transfer bearing 4 is biased toward the drive roller 172 (in the X direction) by a secondary transfer spring 5, which is a biasing member that serves as a biasing member for biasing an opposing member and is formed of a compression coil spring. One end of the secondary transfer spring 5 abuts against the secondary transfer bearing 4, and the other end is supported by the secondary transfer frame 116. The secondary transfer bearing 4 is configured so as to be able to move linearly in the X direction relative to the secondary transfer frame 116 due to the biasing force of the secondary transfer spring 5, and so as to be able to move linearly in the −X direction against the biasing force of the secondary transfer spring 5. Furthermore, a regulating member 2 and a force applying member 3 that constitute the gap adjustment mechanism 10 are provided coaxially with the drive roller 172 at both ends of the drive roller 172 in the rotational axis direction.

[0035] 4(a) during image formation (contact state), the secondary transfer bearing 4 is biased by the secondary transfer spring 5, thereby pressing the secondary transfer roller 109 against the drive roller 172 via the intermediate transfer belt 171. This pressure causes the secondary transfer roller 109 to be pressed against the intermediate transfer belt 171 wound around the drive roller 172, forming a secondary transfer nip N2. During image formation, the biasing force of the secondary transfer spring 5 is applied to the secondary transfer nip N2, and the gap adjustment mechanism 10 is configured so that the biasing force of the secondary transfer spring 5 is not applied to the regulating member 2 and the force applying member 3. As a result, the toner image on the intermediate transfer belt 171 is transferred onto the transfer material S passing through the secondary transfer nip N2.

[0036] On the other hand, in the shipping state (separated state) of the image forming apparatus 100 shown in FIG. 4(b), the gap adjustment mechanism 10 is configured so that the secondary transfer roller 109 supported by the secondary transfer bearing 4 is separated from the intermediate transfer belt 171 and the drive roller 172. As will be described in detail later, in the shipping state of the image forming apparatus 100, the secondary transfer bearing 4, biased by the secondary transfer spring 5, moves linearly in the −X direction relative to its position during image formation and is supported by a regulating member 2 provided on the rotation shaft 1 of the drive roller 172. This prevents the biasing force of the secondary transfer spring 5 from being applied to the secondary transfer roller 109 and the intermediate transfer belt 171, preventing plastic deformation of the elastic body of the secondary transfer roller 109 and the intermediate transfer belt 171 due to the influence of heat during transportation of the image forming apparatus 100. This prevents transfer defects due to insufficient contact pressure at the secondary transfer nip N2 or unevenness on the surface of the intermediate transfer belt 171 caused by such plastic deformation.

[0037] 4. Secondary transfer roller spacing configuration Next, the spacing structure (gap adjustment mechanism) of the secondary transfer roller 109 will be described.

[0038] <Configuration of the gap adjustment mechanism of the comparative example> First, to facilitate understanding of the gap adjusting mechanism of this embodiment, a gap adjusting mechanism of a comparative example will be described. In the comparative example, elements corresponding to those of this embodiment will be denoted by the same reference numerals.

[0039] The gap adjustment mechanism 10 of the comparative example and the gap adjustment mechanism 10 of this embodiment have their components provided at both ends in the rotational axis direction of the secondary transfer roller 109. The configurations of the components at both ends are substantially the same (substantially symmetrical with respect to a plane that passes through the center in the rotational axis direction of the secondary transfer roller 109 and is perpendicular to the rotational axis). Therefore, the following description will focus on the configuration on the drive side.

[0040] FIG. 5 is an exploded perspective view illustrating components of the gap adjustment mechanism 10 of the comparative example. In FIG. 5, only a portion of the drive-side end of the drive roller 172 is shown, cut along the XZ plane, to illustrate the internal configuration. FIG. 6 is a diagram illustrating the gap adjustment mechanism 10 in a separated state (the state of the image forming apparatus 100 at the time of shipment). FIG. 6(a) is a side view of the vicinity of the drive-side end of the drive roller 172 and the secondary transfer roller 109, as viewed in the -Z direction. FIG. 6(b) is a cross-sectional view taken along line AA in FIG. 6(a) (showing a cross-section perpendicular to the rotational axis of the drive roller 172). FIG. 6(c) is a cross-sectional view taken along line BB in FIG. 6(a) (showing a cross-section perpendicular to the rotational axis of the drive roller 172). FIG. 7 is a diagram similar to FIG. 6 illustrating the gap adjustment mechanism 10 in the middle of transitioning from the separated state (FIG. 6) to the contact state (FIG. 8). 8 is a view similar to FIG. 6 for explaining the gap adjustment mechanism 10 in a contact state (state during image formation). The intermediate transfer belt 171 is not shown in FIGS. 6, 7, and 8. The rotation direction of the drive roller 172 during image formation is also referred to as the "C direction," and the direction opposite to the C direction (or +C direction) is also referred to as the "-C direction."

[0041] A regulating member 2 is disposed on the rotation shaft 1 of the drive roller 172 to separate the drive roller (first rotating body) 172 from the secondary transfer roller (second rotating body) 109 (to regulate the distance between the rotation shaft 1 and the secondary transfer bearing 4). The regulating member 2 is an annular member, and its inner circumferential surface 24 comes into contact with an outer circumferential surface 33 of a force applying member 3 (described later). The regulating member 2 is attached to the force applying member 3 so as to be rotatable in the rotation direction of the drive roller 172 and movable in translation along the rotation axis direction of the drive roller 172. The regulating member 2 has a force receiving portion 21, which is adjacent to the inner circumferential surface 24 that comes into contact with the outer circumferential surface 33 of the force applying member 3 and comes into contact with a force applying portion 31 of the force applying member 3 (described later). The force receiving portion 21 is configured as a surface (inclined surface) that extends obliquely with respect to the rotation direction of the drive roller 172 and the rotation axis direction of the drive roller 172. The regulating member 2 also has a groove portion (an engaging recess portion constituting a guide portion) 22 that can engage with a protrusion portion 42 (described later) of the secondary transfer bearing 4 on an outer circumferential surface 23 that can come into contact with the secondary transfer bearing 4. The regulating member 2 is disposed concentrically with the rotation axis 1 of the drive roller 172.

[0042] Further, a force applying member 3 is disposed on the rotary shaft 1 of the drive roller 172. The force applying member 3 is rotatable in conjunction with the drive roller 172 and applies a force to move the regulating member 2. The force applying member 3 is an annular member, and its inner peripheral surface 32 contacts the outer peripheral surface of the rotary shaft 1 of the drive roller 172, and its outer peripheral surface 33 contacts the inner peripheral surface 24 of the regulating member 2. The force applying member 3 has a large-diameter portion on the roller portion 172a side of the drive roller 172 and a small-diameter portion on the end side of the rotary shaft 1 of the drive roller 172, and the outer peripheral surface 33 of the small-diameter portion contacts the inner peripheral surface 24 of the regulating member 2. The force applying member 3 has a force applying portion 31 on its outer peripheral surface 33, which contacts the inner peripheral surface 24 of the regulating member 2, and which contacts the force receiving portion 21 of the regulating member 2. The force applying portion 31 is configured as a protrusion provided on the outer peripheral surface 33 of the force applying member 3 so as to protrude radially from the drive roller 172. The force applying member 3 is disposed concentrically with the rotation shaft 1 of the drive roller 172 and the regulating member 2. The main difference between the configuration of the comparative example and the configuration of this embodiment is the configuration of the force applying member 3.

[0043] In this way, an annular force applying member 3 and an annular regulating member 2 are provided coaxially with the drive roller 172 at both ends in the rotational axis direction of the drive roller 172. In other words, a rotating shaft 1 is provided at one end of the drive roller 172 in the rotational axis direction. The force applying member 3 is provided so that the outer peripheral surface of this rotating shaft 1 and the inner peripheral surface 32 of the force applying member 3 come into contact (substantially mate). Then, the regulating member 2 is provided outside the force applying member 3 so that the outer peripheral surface 33 of the force applying member 3 and the inner peripheral surface 24 of the regulating member 2 come into contact (substantially mate). The rotating shaft 1, force applying member 3, and regulating member 2 of the drive roller 172 are configured concentrically.

[0044] In this example, the core 6 constituting the roller portion 172a of the drive roller 172 is made of a three-arrow pipe, and a rotary shaft (shaft member) 1 is fixed to both ends of this core 6 in the direction of the rotation axis of the drive roller 172 (this also applies to the present example described below). The core 6 has an inner tube portion 61, an outer tube portion 62, and three roller ribs 63 provided to radially connect the inner tube portion 61 and the outer tube portion 62. The force applying member 3 has a rotation stopper portion 35 on an end surface 34 facing the roller portion 172a of the drive roller 172 in the direction of the rotation axis of the drive roller 172. The rotation stopper portion 35 is provided to protrude in the direction of the rotation axis of the drive roller 172 so as to enter inside the roller portion 172a of the drive roller 172. The rotation stopper portion 35 is made of a substantially arc-shaped rib (rib-shaped portion). In the configuration of the comparative example, a first rotation stop end (rotational force receiving portion) 35a, which is the end on the rear end side in the C direction of the rotation stop portion 35, abuts against a first abutment portion (rotational force applying portion) 63a formed by the side surface of one of the roller ribs 63 of the drive roller 172. Also, in the configuration of the comparative example, a second rotation stop end 35b, which is the end on the front end side in the C direction of the rotation stop portion 35, abuts against a second abutment portion 63b formed by the side surface of another of the roller ribs 63 of the drive roller 172. And, in the configuration of the comparative example, the force applying member 3 is attached to the drive roller 172 in a state where the first rotation stop end 35a abuts against the first abutment portion 63a of the drive roller 172. Also, in the configuration of the comparative example, the force applying member 3 is attached to the drive roller 172 in a state where the second rotation stop end 35b also abuts against the second abutment portion 63b of the drive roller 172. Therefore, in the comparative example, the force applying member 3 is configured to rotate substantially integrally with the drive roller 172.

[0045] The secondary transfer bearing 4 also has a bearing portion 41 that rotatably supports the rotation shaft 109b of the secondary transfer roller 109, and a protrusion portion (engagement convex portion constituting a guide portion) 42 that protrudes toward the drive roller 172 and can engage with the groove portion 22 of the regulating member 2 (Figure 6(c)).

[0046] The regulating member 2, the force applying member 3 and the secondary transfer bearing 4 are made of synthetic resin, and the core metal 6 of the driving roller 172 is made of metal (this also applies to the present embodiment described later).

[0047] <Contact Operation of the Gap Adjustment Mechanism of the Comparative Example> As described above, the image forming apparatus 100 is shipped with the secondary transfer roller 109 separated from the intermediate transfer belt 171 and the drive roller 172. Then, the secondary transfer roller 109 automatically contacts the intermediate transfer belt 171 and the drive roller 172 in conjunction with the operation of the image forming apparatus 100. The contact operation (automatic contact operation) of the image forming apparatus 100 in the configuration of the comparative example from the state at the time of shipment to the state during image formation will be described with reference to FIGS. 6 to 8.

[0048] 6 shows the state of the image forming apparatus 100 at the time of shipment, in which the secondary transfer roller 109 is separated from the intermediate transfer belt 171 and the drive roller 172. As shown in FIG. 6(a), the regulating member 2 is provided with a force receiving portion 21 having an inclined surface. The regulating member 2 is attached to the force applying member 3 so as to be rotatable relative to the rotation direction of the drive roller 172 and to be able to translate along the rotation axis direction of the drive roller 172. The force applying member 3 is provided with a force applying portion 31 in contact with the force receiving portion 21 of the regulating member 2. Furthermore, as shown in FIG. 6(b), the force applying member 3 is in a state in which the first rotation stop end portion 35a abuts against the first abutment portion 63a of the drive roller 172 before the image forming apparatus 100 is shipped. For example, before the shipment of the image forming apparatus 100, the force applying member 3 rotates in the direction C in conjunction with the drive roller 172, resulting in the first rotation stop end 35a of the force applying member 3 coming into contact with the first abutment portion 63a of the drive roller 172. Note that in this example, as described above, before the shipment of the image forming apparatus 100, the second rotation stop end 35b of the force applying member 3 also comes into contact with the second abutment portion 63a of the drive roller 172. Furthermore, as shown in FIG. 6(c), the secondary transfer bearing 4 is in a state in which the protrusion 42 abuts against the outer circumferential surface 23 of the regulating member 2.

[0049] 7 shows a state during a contact operation in which the drive roller 172 has rotated in the direction C from the state shown in FIG. 6 as the image forming apparatus 100 starts operating. As shown in FIG. 7(b), as the drive roller 172 rotates in the direction C, the force application member 3 rotates in the direction C in conjunction with the rotation of the drive roller 172. As shown in FIG. 7(c), as the drive roller 172 and the force application member 3 rotate in the direction C in conjunction with the rotation of the drive roller 172 and the force application member 3 in the direction C, the regulating member 2 also rotates in the direction C in conjunction with the rotation of the drive roller 172 and the force application member 3. The regulating member 2 rotates in conjunction with the force application member 3 due to the force application portion 31 of the force application member 3 contacting the force receiving portion 21 (or friction at other contact portions between the regulating member 2 and the force application member 3), etc. Then, the protrusion 42 of the secondary transfer bearing 4 engages with the groove 22 of the regulating member 2. When the drive roller 172 continues to rotate with the two engaged, the rotation of the regulating member 2 in the C direction is restricted, and the inclined force receiving portion 21 of the regulating member 2 receives force from the force applying portion 31 of the force applying member 3 that comes into contact with it. As a result, as shown in Figure 7(a), in conjunction with the rotation of the force applying member 3 in the C direction (movement in the X direction in Figure 7(a)), the regulating member 2 translates in the Y direction (the direction from the center toward the end in the direction of the rotation axis of the drive roller 172).

[0050] 8 shows a state during image formation in which the drive roller 172 further rotates in the C direction from the state shown in FIG. 7 and the secondary transfer roller 109 comes into contact with the intermediate transfer belt 171 and the drive roller 172. As shown in FIG. 8(a), the regulating member 2 further translates in the Y direction from the state shown in FIG. 7, causing the secondary transfer bearing 4, which was supported by the regulating member 2 and whose position in the X direction was regulated, to fall between the regulating member 2 and the force applying member 3. In other words, the engagement between the regulating member 2 and the secondary transfer bearing 4 is released, and the position of the secondary transfer bearing 4 in the X direction is no longer regulated by the regulating member 2. As a result, as shown in FIGS. 8(a) and 8(b), the secondary transfer roller 109 transitions to a contact state in which it comes into contact with the intermediate transfer belt 171 and the drive roller 172.

[0051] After the regulating member 2 has disengaged from the secondary transfer bearing 4, the regulating member 2 continues to rotate in conjunction with the drive roller 172 due to the force application portion 31 of the force application member 3 coming into contact with the force receiving portion 21 (or friction at other contact portions between the regulating member 2 and the force application member 3). When changing from the contact state to the separated state, for example, the regulating member 2 is manually moved in the direction of the rotation axis of the drive roller 172, in the opposite direction to the contact operation described above, so that the regulating member 2 is positioned to come into contact with the secondary transfer bearing 4.

[0052] In this way, the gap adjustment mechanism 10 adjusts the gap (first gap, second gap) between the rotation shaft 1 of the drive roller 172 and the secondary transfer bearing (opposing member) 4 disposed opposite thereto, thereby adjusting the gap (separation, abutment) between the secondary transfer roller 109 and the intermediate transfer belt 171. The gap adjustment mechanism 10 is configured to include a secondary transfer spring 5 that urges the secondary transfer bearing 4 toward the rotation shaft 1 of the drive roller 172, a regulating member 2, and a force applying member 3. The force applying member 3 is attached to the outer peripheral surface of the rotation shaft 1 of the drive roller 172. The regulating member 2 is also attached movably on the outer peripheral surface 33 of the force applying member 3. The regulating member 2 is configured to receive a force that moves on the outer peripheral surface 33 of the force applying member 3 from the force applying member 3 that rotates in conjunction with the drive roller 172.

[0053] When the secondary transfer roller 109, the intermediate transfer belt 171, and the drive roller 172 are shifted from a separated state to a contact state, the regulating member 2 first rotates around the rotation axis of the drive roller 172 together with the force applying member 3, which rotates in conjunction with the drive roller 172. This rotation causes the regulating member 2 to move relative to the secondary transfer bearing 4. This relative movement causes the protrusion 42 of the secondary transfer bearing 4, which has been in sliding contact with the outer circumferential surface 23 of the regulating member 2, to engage (substantially mate) with the groove 22, which is formed on the outer circumferential surface 23 of the regulating member 2 and extends in the direction of the rotation axis of the drive roller 172. This restricts the rotation of the regulating member 2, and the regulating member 2 begins to move (rotate) relative to the force applying member 3, which rotates in conjunction with the drive roller 172. The protrusion 42 and the groove 22 function as anti-rotation portions that restrict the rotation of the regulating member 2 around the rotation axis of the drive roller 172. As a result, the regulating member 2 is allowed to move in the direction of the rotation axis of the drive roller 172, while regulating the rotation of the drive roller 172 around the rotation axis.

[0054] The regulating member 2 receives force from the force applying portion 31 of the force applying member 3 at the force receiving portion 21, and moves relative to the force applying member 3 in the rotational axis direction of the drive roller 172. This force receiving portion 21 is configured to receive a force from the force applying portion 31 of the force applying member 3, including a component force acting in the rotational axis direction of the drive roller 172. As a result, the regulating member 2 moves in the rotational axis direction of the drive roller 172, from the center toward the outside in the rotational axis direction of the drive roller 172, relative to the force applying member 3 and the secondary transfer bearing 4. When the image forming apparatus 100 is shipped, the regulating member 2 is in a position where it acts on the biasing force of the secondary transfer spring 5, specifically, in a position (first position) where it is sandwiched between the rotation shaft 1 of the drive roller 172 and the secondary transfer bearing 4 and exerts a force that resists the biasing force of the secondary transfer spring 5. Then, when operation of the image forming device 100 begins, the regulating member 2 moves in the direction of the rotation axis of the drive roller 172, causing it to move to a position where the way it acts against the spring force of the secondary transfer spring 5 changes compared to the first position, specifically, to a position (second position) where it is not sandwiched between the rotation axis 1 of the drive roller 172 and the secondary transfer bearing 4 and does not exert a force against the spring force of the secondary transfer spring 5.

[0055] <Effect of logistics impact on the gap adjustment mechanism of the comparative example> Next, a description will be given of the influence of a transport shock on the gap adjustment mechanism 10 of the comparative example. Fig. 9 is a view similar to Fig. 6 for explaining the influence of a transport shock on the gap adjustment mechanism 10 of the comparative example.

[0056] 9(c), it is conceivable that the secondary transfer bearing 4 will be subjected to a shipping impact in the -Z direction with the protrusion 42 of the secondary transfer bearing 4 engaged with the groove 22 of the regulating member 2. This would be an unfavorable condition in that the secondary transfer bearing 4 may rotate the regulating member 2 in the -C direction, releasing the separated state. It is also conceivable that the regulating member 2 may rotate due to the influence of vibrations during transportation of the image forming apparatus 100, causing the protrusion 42 of the secondary transfer bearing 4 to engage with the groove 22 of the regulating member 2.

[0057] When the protrusion 42 of the secondary transfer bearing 4 is engaged with the groove 22 of the regulating member 2 and the secondary transfer bearing 4 receives a force in the -Z direction, the force is transmitted to the regulating member 2 due to the engagement between the protrusion 42 and the groove 22. Here, as shown in FIG. 9B, the first rotation stop end 35a of the force applying member 3 is in a state of abutting against the first abutment portion 63a of the drive roller 172. Therefore, in response to the force in the -Z direction from the secondary transfer bearing 4, the force applying member 3 does not have a degree of freedom to rotate (move) in the -C direction. In addition, because the drive roller 172 is connected to a drive source (not shown), it does not have a degree of freedom to rotate in the -C direction (and the C direction). Therefore, the regulating member 2, which receives a force in the -Z direction from the secondary transfer bearing 4, rotates in the -C direction (the -X direction in FIG. 9A) relative to the force applying member 3 and the drive roller 172, which have no degree of freedom to rotate in the -C direction. Furthermore, since the regulating member 2 is provided with an inclined force receiving portion 21, the regulating member 2 rotates with the force applying portion 31 of the force applying member 3 sliding along the force receiving portion 21, causing the regulating member 2 to translate in the Y direction. As a result, the secondary transfer bearing 4, whose position in the X direction was restricted by the regulating member 2, may fall between the regulating member 2 and the force applying member 3, causing the secondary transfer roller 109 to enter a contact state in which it contacts the intermediate transfer belt 171 and the drive roller 172.

[0058] If the image forming apparatus 100 shifts from the separated state to the contact state during transportation, there is a possibility that plastic deformation will occur in the elastic body of the secondary transfer roller 109 and the intermediate transfer belt 171 due to the influence of heat during transportation of the image forming apparatus 100. This may lead to image defects after the image forming apparatus 100 arrives. Therefore, it may be necessary to use a more extensive packaging form to reduce physical distribution shock so that the separated state can be maintained even during anticipated transportation states of the image forming apparatus 100.

[0059] <Configuration of the gap adjustment mechanism of this embodiment> Next, the gap adjustment mechanism 10 of this embodiment will be described. FIG. 10 is a perspective view of the force application member 3 constituting the gap adjustment mechanism 10 of this embodiment. FIG. 11 is a diagram illustrating the gap adjustment mechanism 10 in a separated state (a state at the time of shipment of the image forming apparatus 100). FIG. 11(a) is a side view of the vicinity of the drive-side ends of the drive roller 172 and the secondary transfer roller 109 as viewed in the -Z direction. FIG. 11(b) is a cross-sectional view taken along line AA in FIG. 11(a) (showing a cross-section perpendicular to the rotational axis direction of the drive roller 172). FIG. 11(c) is a cross-sectional view taken along line BB in FIG. 11(a) (showing a cross-section perpendicular to the rotational axis direction of the drive roller 172). FIG. 12 is a diagram similar to FIG. 11 illustrating the gap adjustment mechanism 10 in the middle of transitioning from the separated state (FIG. 11) to the contact state (FIG. 13). FIG. 13 is a diagram similar to FIG. 11 illustrating the gap adjustment mechanism 10 in the contact state (a state during image formation). 11, 12, and 13, the intermediate transfer belt 171 is not shown. Note that the configuration of the gap adjustment mechanism 10 in this embodiment, excluding the force application member 3, is substantially the same as that of the gap adjustment mechanism 10 in the comparative example described above, and therefore the description thereof will be omitted as appropriate.

[0060] A force application member 3 is disposed on the rotation shaft 1 of the drive roller 172. The force application member 3 is rotatable in conjunction with the drive roller 172 and applies a force to move the regulating member 2. The force application member 3 is an annular member, and its inner peripheral surface 32 contacts the outer peripheral surface of the rotation shaft 1 of the drive roller 172, and its outer peripheral surface 33 contacts the inner peripheral surface 24 of the regulating member 2. The force application member 3 has a large-diameter portion on the roller portion 172a side of the drive roller 172 and a small-diameter portion on the end side of the rotation shaft 1 of the drive roller 172, and the outer peripheral surface 33 of the small-diameter portion contacts the inner peripheral surface 24 of the regulating member 2. The force application member 3 is attached to the rotation shaft 1 of the drive roller 172 so as to be rotatable in the rotation direction of the drive roller 172. The force application member 3 has a force application portion 31 on its outer peripheral surface 33, which contacts the inner peripheral surface 24 of the regulating member 2, and which contacts the force receiving portion 21 of the regulating member 2. The force applying portion 31 is configured as a protrusion provided on the outer peripheral surface 33 of the force applying member 3 so as to protrude in the radial direction of the drive roller 172. The force applying member 3 is disposed concentrically with the rotation axis 1 of the drive roller 172 and the regulating member 2.

[0061] In this embodiment, as described above, the core 6 constituting the roller portion 172a of the drive roller 172 is made of a three-arrow pipe, and the rotation shaft (shaft member) 1 is fixed to the end of the core 6 in the direction of the rotation axis of the drive roller 172. The force applying member 3 has a rotation stopper 35 on an end surface 34 that faces the roller portion 172a of the drive roller 172 in the direction of the rotation axis of the drive roller 172. The rotation stopper 35 is provided to protrude in the direction of the rotation axis of the drive roller 172 so as to enter inside the roller portion 172a of the drive roller 172. The rotation stopper 35 is made of a substantially arc-shaped rib (rib-shaped portion). A first rotation stopper end (rotational force receiving portion) 35a, which is the end on the rear end side of the rotation stopper 35 in the C direction, can abut against an abutment portion (rotational force applying portion) 63a formed by the side surface of one roller rib portion 63 of the drive roller 172. On the other hand, in this embodiment, the rotation stopper 35 is configured so that the second rotation stopper end 35b, which is the distal end in the C direction, does not abut against the side surface of the roller rib portion 63 of the drive roller 172. FIG. 16 is a perspective view comparing the force application member 3 constituting the gap adjustment mechanism 10 of the comparative example described above with the force application member 3 constituting the gap adjustment mechanism 10 of this embodiment, with FIG. 16(a) showing the configuration of the comparative example and FIG. 16(b) showing the configuration of this embodiment. The extension angle of the rib constituting the rotation stopper 35 of the force application member 3 in the configuration of the comparative example (the angle in the rotation direction of the drive roller 172 between the first rotation stopper end 35a and the second rotation stopper end 35b about the rotation axis of the drive roller 172) is defined as Ra. Furthermore, the extension angle of the rib constituting the rotation stopper 35 of the force application member 3 in the configuration of this embodiment is defined as Rb. The extension angle of the rotation stopper 35 in the configuration of this embodiment is smaller than that in the configuration of the comparative example (Ra > Rb). In the configuration of the comparative example, the extension angle Ra of the rotation stopper 35 is substantially the same as the angle between the roller rib portions 63 of the drive roller 172 (the angle in the rotation direction of the drive roller 172 between the side surfaces of adjacent roller rib portions 63 around the rotation axis of the drive roller 172). In the configuration of this embodiment, the extension angle Rb of the rotation stopper 35 is smaller than the angle between the roller rib portions 63 of the drive roller 172.

[0062] In this embodiment, the force application member 3 further includes a flexible (elastically deformable) restricting and urging portion 36 on an end face 34 facing the roller portion 172a of the drive roller 172 in the direction of the rotation axis of the drive roller 172. In this embodiment, the restricting and urging portion 36 restricts the relative position (relative phase) of the force application member 3 with respect to the drive roller 172 in the direction of rotation of the drive roller 172 when the drive roller 172 stops rotating. In other words, the restricting and urging portion 36 constitutes a position restricting means for restricting the position of the force application member 3 in the direction of rotation. The restricting and urging portion 36 is provided to protrude in the direction of the rotation axis of the drive roller 172 so as to enter inside the roller portion 172a of the drive roller 172. The restricting and urging portion 36 includes a flexible plate-shaped base portion 36b having one end connected to the end face 34 and a restricting action portion 36a provided at the other end of the base portion 36b. The base portion 36b is configured to be deformable in a direction along the rotation direction of the drive roller 172. The restricting action portion 36a is configured to be able to come into contact with an urging force receiving portion 63c formed on the side surface of the roller rib portion 63 of the drive roller 172. In this embodiment, the restricting action portion 36a is configured to be able to come into contact with an urging force receiving portion 63c formed on the side surface of a roller rib portion 63 other than the two roller rib portions 63 adjacent to the first rotation stop end portion 35a and the second rotation stop end portion 35b.

[0063] The force application member 3 can rotate in the direction C in conjunction with the drive roller 172 when the first rotation stop end 35a abuts against the abutment portion 63a of the drive roller 172. At this time, the flexible restricting and urging portion 36 abuts against the urging-receiving portion 63c of the drive roller 172 and elastically deforms so as to fall in the direction C. Furthermore, when the rotation of the drive roller 172 stops, the restricting and urging portion 36 abuts against the urging-receiving portion 36c of the drive roller 172, thereby restricting the stop position of the force application member 3 relative to the drive roller 172 in the rotation direction of the drive roller 172. Furthermore, when elastically deformed as described above, the restricting and urging portion 36 urges the force application member 3 to rotate relative to the drive roller 172 in a direction returning to the stop position by its elastic restoring force. As a result, in this embodiment, when the drive roller 172 stops rotating, the force applying member 3 is in a state where there is a gap (idle region E) in the rotation direction of the drive roller 172 between the abutment portion 63a of the drive roller 172 and the first rotation stop end portion 35a of the force applying member 3. The operation of the gap adjustment mechanism 10 of this embodiment will be described in detail later.

[0064] In this embodiment, the force applying member 3 further has a flexible (elastically deformable) second restrictive urging portion 37 on an end surface 34 facing the roller portion 172a of the drive roller 172 in the direction of the rotation axis of the drive roller 172. In this embodiment, the second restrictive urging portion 37 restricts the relative position (relative phase) of the force applying member 3 to the drive roller 172 in the rotation direction of the drive roller 172 when the drive roller 172 stops rotating. The second restrictive urging portion 37 is provided to protrude in the direction of the rotation axis of the drive roller 172 so as to enter inside the roller portion 172a of the drive roller 172. The second restrictive urging portion 37 is provided adjacent to the restrictive urging portion (first restrictive urging portion) 36 and has a configuration corresponding to the restrictive urging portion 36. That is, the second restrictive biasing portion 37 has a flexible, plate-shaped base portion 37b, one end of which is connected to the end surface 34, and a restrictive action portion 37a provided at the other end of the base portion 37b. The base portion 37b is configured to be deformable in the direction of rotation of the drive roller 172. The restrictive action portion 37a is configured to be able to abut against a second biasing force receiving portion 63d formed on a side surface of the roller rib portion 63 of the drive roller 172. In this embodiment, the restrictive action portion 37a of the second restrictive biasing portion 37 is configured to be able to abut against a second biasing force receiving portion 63d formed on the opposite side surface of the roller rib portion 63 of the drive roller 172, the same portion that abuts against the restrictive action portion 36a of the restrictive biasing portion 36. However, the present invention is not limited to this configuration, and the second restrictive biasing portion 37 may not be provided. The function of the second restrictive biasing portion 37 will be described later.

[0065] <Contact Operation of the Distance Adjusting Mechanism of the Present Embodiment> As described above, the image forming apparatus 100 is shipped with the secondary transfer roller 109 separated from the intermediate transfer belt 171 and the drive roller 172. Then, the secondary transfer roller 109 automatically contacts the intermediate transfer belt 171 and the drive roller 172 in conjunction with the operation of the image forming apparatus 100. The contact operation (automatic contact operation) in this embodiment, which changes the state of the image forming apparatus 100 from the state at the time of shipment to the state during image formation, will be described with reference to FIGS.

[0066] FIG. 11 shows the state of the image forming apparatus 100 at the time of shipment, in which the secondary transfer roller 109 is separated from the intermediate transfer belt 171 and the drive roller 172. As shown in FIG. 11(a), the regulating member 2 is provided with a force receiving portion 21 having a sloped surface. The regulating member 2 is attached to the force applying member 3 so as to be rotatable relative to the rotation direction of the drive roller 172 and to be able to translate along the rotation axis direction of the drive roller 172. The force applying member 3 is provided with a force applying portion 31 that contacts the force receiving portion 21 of the regulating member 2. Furthermore, as shown in FIG. 11(b), in this embodiment, before the image forming apparatus 100 is shipped, the force applying member 3 is stopped with the first rotation stop end portion 35a preceding the abutment portion 63a of the drive roller 172 in the direction C by the regulating biasing portion 36 contacting the biasing force receiving portion 63c of the drive roller 172. As a result, an idling region E, which is a gap in the rotation direction of the drive roller 172, is provided between the abutting portion 63a of the drive roller 172 and the first rotation stop end 35a of the force application member 3. For example, before shipping of the image forming apparatus 100, the force application member 3 rotates in the direction C in conjunction with the drive roller 172, resulting in the restrictive urging portion 36 of the force application member 3 coming into contact with the urging force receiving portion 63c of the drive roller 172. Note that, as will be described later, the force application member 3 may be in a state in which the restrictive urging portion 36 and the second restrictive urging portion 37 are in contact with the urging force receiving portion 63c and the second urging force receiving portion 63d of the drive roller 172, respectively, before shipping of the image forming apparatus 100. In other words, the restrictive urging portion 36 and the second restrictive urging portion 37 may sandwich the roller rib portion 63 of the drive roller 172, thereby restricting the stop position of the force application member 3 relative to the drive roller 172 in the rotation direction of the drive roller 172. Furthermore, as shown in FIG. 11(c), the secondary transfer bearing 4 is in a state where the protrusion 42 abuts on the outer circumferential surface 23 of the regulating member 2.

[0067] FIG. 12 shows a state during a contact operation in which the drive roller 172 rotates in the direction C from the state shown in FIG. 11 as the image forming apparatus 100 starts operating. Because the restricting and biasing portion 36 of the force applying member 3 is in contact with the bias receiving portion 63c of the drive roller 172, the force applying member 3 rotates in the direction C in conjunction with the rotation of the drive roller 172 in the direction C. Furthermore, as the drive roller 172 and the force applying member 3 rotate in the direction C, the regulating member 2 also rotates in conjunction with the rotation of the drive roller 172 and the force applying member 3 in the direction C. The regulating member 2 rotates in conjunction with the force applying member 3 due to the force applying portion 31 of the force applying member 3 contacting the force receiving portion 21 (or friction at other contact portions between the regulating member 2 and the force applying member 3), etc. Then, as shown in FIG. 12(c), the protrusion 42 of the secondary transfer bearing 4 engages with the groove 22 of the regulating member 2. As the drive roller 172 continues to rotate with the two engaged, the restricting and biasing portion 36 of the force application member 3, which is in contact with the bias receiving portion 63c of the drive roller 172, deforms, as shown in FIG. 12(b). As a result, the abutting portion 63a of the drive roller 172 approaches the first rotation stop end 35a of the force application member 3, reducing the idling region E. At this time, as shown in FIG. 12(a), the relative phase between the restricting member 2 and the force application member 3 is maintained, and the restricting member 2 does not translate in the Y direction. After that, as the drive roller 172 further rotates in the C direction, the first rotation stop end 35a of the force application member 3 abuts against the abutting portion 63a of the drive roller 172, and the force application member 3 begins to rotate in the C direction in conjunction with the rotation of the drive roller 172. As a result, similar to the state shown in FIG. 7 for the comparative example, the rotation of the restricting member 2 in the C direction is restricted, and the inclined force receiving portion 21 of the restricting member 2 receives force from the force application portion 31 of the force application member 3. As a result, in conjunction with the rotation of the force application member 3 in the C direction (movement in the X direction in Figure 12(a)), the regulating member 2 begins to move translationally in the Y direction (the direction from the center toward the end in the rotation axis direction of the drive roller 172).

[0068] 13 shows a state during image formation in which, after passing through the state shown in FIG. 12, the regulating member 2 begins to translate as described above, and then the drive roller 172 further rotates in the C direction, causing the secondary transfer roller 109 to come into contact with the intermediate transfer belt 171 and the drive roller 172. As shown in FIG. 13(a), as the regulating member 2 translates in the Y direction from the state shown in FIG. 12, the secondary transfer bearing 4, which was supported by the regulating member 2 and whose position in the X direction was restricted, falls between the regulating member 2 and the force applying member 3. In other words, the engagement between the regulating member 2 and the secondary transfer bearing 4 is released, and the position of the secondary transfer bearing 4 in the X direction is no longer restricted by the regulating member 2. As a result, as shown in FIGS. 13(a) and 13(b), the secondary transfer roller 109 transitions to a contact state in which it comes into contact with the intermediate transfer belt 171 and the drive roller 172. Furthermore, as shown in FIG. 13(b), as a result of the rotation prevention by the regulating member 2 being released, the force applying member 3 rotates in the -C direction relative to the drive roller 172 due to the biasing force of the regulating biasing portion 36, and returns to a state where the idling region E is provided and stops.

[0069] After the regulating member 2 has disengaged from the secondary transfer bearing 4, the regulating member 2 continues to rotate in conjunction with the drive roller 172 due to the force application portion 31 of the force application member 3 coming into contact with the force receiving portion 21 (or friction at other contact portions between the regulating member 2 and the force application member 3). When changing from a contact state to a separated state, for example, the force application member 3 is placed in a position where an idling region E is provided, and the regulating member 2 is manually moved in the direction of the rotation axis of the drive roller 172, in the opposite direction to the contact operation described above, so that the regulating member 2 is placed in a position where it comes into contact with the secondary transfer bearing 4.

[0070] <Operation of the gap adjustment mechanism of this embodiment against physical distribution shock> Next, the operation of the gap adjustment mechanism 10 of this embodiment when subjected to a shipping shock will be described. Figure 14 is a view similar to Figure 11 for explaining the operation of the gap adjustment mechanism 10 of this embodiment when subjected to a shipping shock.

[0071] 14(c), it is conceivable that the secondary transfer bearing 4 will be subjected to a shipping impact in the -Z direction with the protrusion 42 of the secondary transfer bearing 4 engaged with the groove 22 of the regulating member 2. In this case, as described above, it is an unfavorable condition in that there is a possibility that the secondary transfer bearing 4 will rotate the regulating member 2 in the -C direction, releasing the separated state. It is also conceivable that the regulating member 2 will rotate due to the influence of vibrations during transportation of the image forming apparatus 100, causing the protrusion 42 of the secondary transfer bearing 4 to engage with the groove 22 of the regulating member 2.

[0072] When the secondary transfer bearing 4 receives a force in the -Z direction with the protrusion 42 of the secondary transfer bearing 4 engaged with the groove 22 of the regulating member 2, the engagement between the protrusion 42 and the groove 22 transmits the force to the regulating member 2. Here, as shown in FIG. 14B , in this embodiment, unlike the configuration of the comparative example, the force applying member 3 is configured such that the regulating and biasing portion 36 contacts the bias-receiving portion 63c of the drive roller 172 and the first rotation stop end 35a precedes the abutting portion 63a of the drive roller 172 in the C direction. As a result, an idling region E, which is a gap in the rotation direction of the drive roller 172, is provided between the abutting portion 63a of the drive roller 172 and the first rotation stop end 35a of the force applying member 3. Therefore, in response to a force from the secondary transfer bearing 4 in the -Z direction, the force applying member 3 has a degree of freedom of rotation (movement) in the -C direction equivalent to the idling region E. As in the configuration of the comparative example, the drive roller 172 is connected to a drive source (not shown), and therefore does not have the degree of freedom to rotate in the −C direction (and the C direction).

[0073] Therefore, even if the force application member 3 rotates in the -C direction due to a logistics impact in the -Z direction, the force application member 3 and the regulating member 2 rotate integrally within the idling region E. The force application member 3 rotates integrally with the regulating member 2 due to the force application portion 31 contacting the force receiving portion 21 of the regulating member 2 (or friction at other contact portions between the force application member 3 and the regulating member 2). The regulating biasing portion 36 elastically deforms with a force weaker than the force applied to the regulating member 2 when translating the regulating member 2. The idling region E is configured with a margin for the amount of rotation of the force application member 3 due to the logistics impact. Therefore, even if the force application member 3 receives a logistics impact, the first rotation stop end 35a of the force application member 3 abuts against the abutment portion 63a of the drive roller 172, preventing the regulating member 2 from translating in the Y direction, as in the comparative example. As a result, the secondary transfer bearing 4, whose position in the X direction was restricted by the regulating member 2, does not fall between the regulating member 2 and the force application member 3, and the separated state is maintained. In other words, in a configuration in which the image forming device 100 is shipped in a separated state and transitions from the separated state to an abutted state in conjunction with the operation of the image forming device 100, it is possible to prevent the separated state from being accidentally released and transitioning to an abutted state due to impact during logistics.

[0074] As described above, the idling region E can be set appropriately taking into consideration the amount of rotation of the force application member 3 due to a logistics impact, etc. For example, the extension angle of the idling region E (the angle in the rotation direction of the drive roller 172 between the abutment portion 63a and the first rotation stop end portion 35a, centered on the rotation axis of the drive roller 172) is set to about 10 degrees or more and 45 degrees or less, more preferably about 15 degrees or more and 30 degrees or less.

[0075] Here, FIG. 15 is a partially enlarged view of FIG. 14(c). As shown in FIG. 15, in this embodiment, the protrusion 42 of the secondary transfer bearing 4 is formed in a shape that bites into the regulating member 2 in a direction that stops the rotation of the drive roller 172 in the C direction. That is, the protrusion 42 is formed so as to protrude toward the drive roller 172, inclined in the −C direction with respect to the normal direction of the circumscribing circle of the regulating member 2 at the position of the groove 22. Therefore, compared to when the secondary transfer bearing 4 is subjected to a logistics impact in the +Z direction, when the secondary transfer bearing 4 is subjected to a logistics impact in the −Z direction, the protrusion 42 bites into the regulating member 2 (groove 22), making it easier to rotate the regulating member 2 in the −C direction. Therefore, as described above, by providing the idling region E in consideration of the logistics impact in the −Z direction (rotation of the regulating member 2 in the −C direction), malfunction of the gap adjustment mechanism 10 can be effectively suppressed.

[0076] On the other hand, it is also conceivable that the secondary transfer bearing 4 receives a logistics impact in the +Z direction, causing the protrusion 42 to rotate the regulating member 2 in the +C direction. Here, for example, in order to use common components for the regulating member 2 and the force applying member 3 provided at both ends of the drive roller 172 in the rotational axis direction, a force receiving portion and a force applying portion for the both ends can be provided on a single regulating member 2 and force applying member 3. For example, the regulating member 2 can be provided with force receiving portions (with inclined surfaces inclined in opposite directions relative to the rotational direction) for the both ends, symmetrically with respect to a plane passing through the rotational axis of the drive roller 172 (see FIG. 5 ). Correspondingly, the force applying member 3 can be provided with force applying portions for the both ends, symmetrically with respect to a plane passing through the rotational axis of the drive roller 172 (not shown). In such a case, if the secondary transfer bearing 4 receives a logistics impact in the +Z direction and the protrusion 42 rotates the regulating member 2 in the +C direction, it is conceivable that the engagement between the regulating member 2 and the secondary transfer bearing 4 will be disengaged due to an action corresponding to that described above. 14(b), a second restrictive biasing portion 37 can be provided on the force application member 3 at a location facing the restrictive biasing portion 36 across the bias receiving portion 36c, thereby providing an idling region F. In this case, when the drive roller 172 stops rotating, the second restrictive biasing portion 37 abuts against the second bias receiving portion 36d of the drive roller 172, thereby restricting the stop position of the force application member 3 relative to the drive roller 172 in the rotation direction of the drive roller 172. Furthermore, when elastically deformed, the second restrictive biasing portion 37 urges the force application member 3 by its elastic restoring force to rotate the force application member 3 relative to the drive roller 172 in a direction returning to the stop position. As a result, when the drive roller 172 stops rotating, the force application member 3 is in a state where a gap (idling region F) is formed between the second rotation stop end portion 35b of the force application member 3 and the second abutment portion 63b of the drive roller 172 in the rotation direction of the drive roller 172. Therefore, even when the secondary transfer bearing 4 rotates the regulating member 2 in the +C direction due to a shipping impact, the same effect as when the secondary transfer bearing 4 rotates the regulating member 2 in the -C direction described above can be obtained.

[0077] As described above, in this embodiment, when a logistics impact is applied, the force application member 3 and the regulating member 2 rotate integrally with respect to the drive roller 172, preventing the transition from a separated state to a contact state. Therefore, it is desirable that the rotational resistance between the drive roller 172 and the force application member 3 be small. From this perspective, it is desirable that the diameter of the contact portion between the drive roller 172 and the force application member 3 in the direction of the rotation axis of the drive roller 172 be small. Therefore, as shown in FIG. 10 , in this embodiment, an end contact portion (inner annular surface) 38 that contacts the end face of the roller portion 172a of the drive roller 172 is provided on the side of the force application member 3 facing the end face of the roller portion 172a of the drive roller 172. The end contact portion 38 is provided so as to protrude toward the roller portion 172a of the drive roller 172, relative to the end face 34 on which the rotation stopper 35 and the regulating biasing portion 36 (and the second regulating biasing portion 37) of the force application member 3 are provided. The end contact portion 38 has an annular or arcuate shape so as to surround at least a portion of the outer circumferential surface of the rotary shaft 1 of the drive roller 172. The outer diameter of the end contact portion 38 is smaller than the outer diameter of the roller portion 172a of the drive roller 172. The inner diameter of the end contact portion 38 is approximately the same as the inner diameter of the inner circumferential surface 32 that contacts the rotary shaft 1 of the drive roller 172, and is formed so as to constitute the edge of the inner circumferential surface 32. By providing the end contact portion 38, the rotational resistance between the drive roller 172 and the force applying member 3 can be reduced.

[0078] As described above, in the image forming apparatus 100 of this embodiment, the distance adjustment mechanism 10 that adjusts the distance between the rotating shaft 1 of the rotating body (drive roller) 172 and the opposing member (secondary transfer bearing) 4 arranged opposite the rotating shaft 1 includes a biasing member (secondary transfer spring) 5 that biases the opposing member 4 toward the rotating shaft 1, a regulating member 2 that regulates the distance and is movably attached to the rotating shaft 1, a force applying member 3 that is rotatably attached to the rotating shaft 1 in conjunction with the rotation of the rotating body 172 in a predetermined rotation direction and has a force applying portion 31 that applies a force to the regulating member 2 to move it, and an elastically deformable position regulating portion (regulating biasing portion) 36 that regulates the position of the force applying member 3. The regulating member 2 is provided with a force receiving portion 21 that receives force from the force applying member 3 that rotates in the predetermined rotational direction in conjunction with the rotation of the rotating body 172 in the predetermined rotational direction, and is configured to receive a force including a component force acting from the force applying portion 31 in the rotational axis direction of the rotating body 172 due to relative movement between the regulating member 2 and the force applying member 3, and is movable from a first position where it acts on the biasing force of the biasing member 5 so that the distance becomes a predetermined distance due to rotation of the force applying member 3 in the predetermined rotational direction, to a second position different from the first position in the rotational axis direction where the way in which the biasing force acts on the biasing member 5 changes with respect to the first position. Furthermore, the position regulating unit 36 ​​regulates the position of the force-giving member 3 in the predetermined rotational direction when the rotation of the rotating body 172 stops, and is configured to be elastically deformed in accordance with the rotation of the rotating body 172 in the predetermined rotational direction when the force-giving member 3 rotates in the predetermined rotational direction in conjunction with the rotation of the rotating body 172 in the predetermined rotational direction and the regulating member 2 moves from the first position to the second position, from the time the rotating body 172 starts to rotate in the predetermined rotational direction to the time the regulating member 2 starts to move from the first position to the second position.In this embodiment, the force applying member 3 has a rotational force receiving portion (first rotation stop end portion) 35a that receives a force from the rotating body 172 to rotate the force applying member 3 in the predetermined rotational direction, and the rotating body 172 has a rotational force applying portion (butting portion) 63a that abuts against the rotational force receiving portion 35a to apply a force to the force applying member 3 to rotate the force applying member 3 in the predetermined rotational direction, and an urging force receiving portion 63c that abuts against the position restricting portion 36, and the position restricting portion 36 is provided on the force applying member 3 and abuts against the urging force receiving portion 63c. The position of the force application member 3 relative to the rotating body 172 in the predetermined rotation direction when the rotating body 172 stops rotating is restricted to a position where the rotational force receiving portion 35a precedes the rotational force application portion 63a in the predetermined rotation direction, and the position restriction portion 36 abuts against the biasing force receiving portion 63c between the time when the rotating body 172 starts rotating in the predetermined rotation direction and the time when the rotational force application portion 63a abuts against the rotational force receiving portion 35a, and is elastically deformed in accordance with the rotation of the rotating body 172 in the predetermined rotation direction. The gap adjustment mechanism 10 may also have an elastically deformable second position restriction portion 37 that restricts the position of the force application member 3. In this case, the second position restriction portion 37 is configured to restrict the position of the force application member 3 in the predetermined rotation direction when the rotating body 172 stops rotating, and to be elastically deformed in accordance with the rotation of the rotating body 172 in the opposite direction to the predetermined rotation direction when the rotating body 172 rotates in the opposite direction to the predetermined rotation direction. In addition, in this embodiment, the rotating body 172 has a roller portion 172a and a rotating shaft 1 protruding from the end of the roller portion 172a in the direction of the rotation axis, and the force-applying member 3 has a contact portion 38 that contacts the end face of the roller portion 172a in the direction of the rotation axis and has an outer diameter smaller than the outer diameter of the roller portion 172.

[0079] In this embodiment, the first position is a position where the regulating member 2 exerts a force against the biasing force so that the gap becomes a predetermined gap, and the second position is a position where the regulating member 2 does not exert a force against the biasing force. Furthermore, in this embodiment, the first position is a position where the regulating member 2 is sandwiched between the rotating shaft 1 and the opposing member 4, and the second position is a position where the regulating member 2 is not sandwiched between the rotating shaft 1 and the opposing member 4. Furthermore, in this embodiment, when the regulating member 2 is in the first position, the gap is regulated to a first gap, and when the regulating member 2 is in the second position, the gap becomes a second gap that is narrower than the first gap. Furthermore, in this embodiment, the force receiving portion 21 is a surface that extends obliquely with respect to the predetermined rotation direction and the rotation axis direction, and the force applying portion 31 is a protrusion that abuts against the surface. In this embodiment, the gap adjustment mechanism 10 includes a guide portion that restricts movement of the restricting member 2 to allow relative movement between the restricting member 2 and the force application member 3, and guides the restricting member 2 from the first position to the second position. In this embodiment, the guide portion is composed of a groove 22 provided in the restricting member 2 and extending in the rotation axis direction, and a protrusion 42 provided in the opposing member 4 and engageable with the groove 22. When the protrusion 42 engages with the groove 22, movement of the restricting member 2 in the rotation axis direction is permitted, while movement of the rotating body 172 around the rotation axis is restricted. In this embodiment, the restricting member 2 and the force application member 3 are each annular members, the force application member 3 is attached to the outer peripheral surface of the rotating shaft 1, and the restricting member 2 is attached to the outer peripheral surface of the force application member 3. In this embodiment, the first position is closer to the center of the rotating body 172 in the rotation axis direction than the second position. In this embodiment, the regulating member 2 and the force applying member 3 are provided on both end sides of the rotating body 172 in the direction of the rotation axis. In this embodiment, the opposing member 4 is a support member (secondary transfer bearing) that rotatably supports the second rotating body (secondary transfer roller) 109, and is provided so as to be movable toward and away from the rotating shaft 1.In this embodiment, the rotating body 172 is a roller (drive roller) that stretches the belt (intermediate transfer belt) 171 that carries the toner image, and the second rotating body 109 is a roller (secondary transfer roller) that contacts the rotating body 172 via the belt 171 when the regulating member 2 is in the second position, and forms a transfer section N2 for transferring the toner image from the belt 171 to the recording material S. In this embodiment, the second rotating body 109 is separated from the belt 171 when the regulating member 2 is in the first position.

[0080] As described above, according to this embodiment, it is possible to prevent the gap between the rotating shaft 1 and the secondary transfer bearing (opposing member) 4, which is adjusted by the gap adjustment mechanism 10, from being changed by external forces such as impacts during transportation. This makes it possible to stably maintain the gap between the secondary transfer roller 109 and the intermediate transfer belt 171 and the drive roller 172.

[0081] [Example 2] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are assigned the same reference numerals as those of embodiment 1, and detailed descriptions thereof will be omitted.

[0082] In this embodiment, the configuration of the force application member 3 in the distance adjustment mechanism 10 is different from that in the first embodiment.

[0083] 17A and 17B are diagrams for explaining the gap adjustment mechanism 10 in the separated state (the state at the time of shipment of the image forming apparatus 100) in this embodiment (the intermediate transfer belt 171 is not shown). FIG. 17A is a side view of the vicinity of the drive side end of the drive roller 172 and the secondary transfer roller 109 as viewed in the -Z direction. FIG. 17B is a cross-sectional view taken along line AA in FIG. 17A (showing a cross section perpendicular to the rotational axis direction of the drive roller 172).

[0084] As shown in FIG. 17(b), in the gap adjustment mechanism 10 of the present embodiment, an elastically deformable restricting and biasing member 7 is provided as a separate member from the force application member 3, instead of the restricting and biasing member 36 provided on the force application member 3 in the first embodiment. In the present embodiment, the restricting and biasing member 7 restricts the relative position (relative phase) of the force application member 3 with respect to the drive roller 172 in the rotation direction of the drive roller 172 when the drive roller 172 stops rotating. The restricting and biasing member 7 is made of an elastic member formed using an elastically deformable material (elastic body) such as sponge or rubber. The restricting and biasing member 7 is disposed between the pressing portion (rotational force application portion) 63e corresponding to the abutting portion 63a of the drive roller 172 in the first embodiment and the first rotation stop end portion (rotational force receiving portion) 35a of the force application member 3 in the rotation direction of the drive roller 172. An end 71 on the rear end side in the C direction of the regulating and biasing member 7 comes into contact with the pressing portion 63e of the drive roller 172, and an end 72 on the front end side in the C direction of the regulating and biasing member 7 comes into contact with the first rotation stop end 35a of the force applying member 3. The force applying member 3 is configured such that the first rotation stop end 35a of the force applying member 3 precedes the pressing portion 63e of the drive roller 172 in the C direction due to the regulating and biasing member 7.

[0085] Even with this configuration, it is possible to provide the same idling region E as in the first embodiment, and to prevent disengagement between the regulating member 2 and the secondary transfer bearing 4 even when subjected to a physical distribution shock. Furthermore, by using the regulating and biasing member 7 that is a separate member from the force applying member 3, it is possible to more flexibly adjust the biasing force and ease of deformation of the position regulating means that regulates the position of the force applying member 3 in the rotational direction, depending on the hardness of the sponge or rubber that constitutes it.

[0086] Here, when the secondary transfer roller 109, the intermediate transfer belt 171, and the drive roller 172 are changed from a separated state to a contact state, the pressing portion 63e of the drive roller 172 presses the regulating and biasing member 7 in a compressed state, thereby rotating the force applying member 3. That is, in this embodiment, the first rotation stop end portion 35a receives a force that rotates the force applying member 3 from the pressing portion 63e via the regulating and biasing member 7. This causes the regulating member 2 to translate in the direction of the rotation axis of the drive roller 172, similar to the first embodiment.

[0087] As described above, in this embodiment, the force applying member 3 has a rotational force receiving portion (first rotation stop end portion) 35a that receives a force from the rotating body 172 that rotates the force applying member 3 in a predetermined rotational direction of the rotating body 172, the rotating body 172 has a rotational force applying portion (pressing portion) 63e that applies a force that rotates the force applying member 3 in the predetermined rotational direction to the rotational force receiving portion 35a, and the position restricting portion (restrictive biasing member) 7 is made up of an elastic member that is arranged so as to be sandwiched between the rotational force applying portion 63e and the rotational force receiving portion 35a in the predetermined rotational direction. The position of the force applying member 3 relative to the rotating body 172 in the predetermined rotation direction when the rotating body 172 stops rotating is restricted to a position where the rotational force receiving portion 35a precedes the rotational force applying portion 63e in the predetermined rotation direction, and the position restricting portion 7 transmits the force that rotates the force applying member 3 in the predetermined rotation direction from the rotational force applying portion 63e to the rotational force receiving portion 35a in a state where it is compressed and elastically deformed between the rotational force applying portion 63e and the rotational force receiving portion 35a as the rotating body 172 rotates in the predetermined rotation direction.

[0088] In order to provide an idling region F similar to that described in the first embodiment, a second restrictive urging member (not shown) may be provided in the gap adjustment mechanism 10 as a separate member from the force application member 3, instead of the second restrictive urging portion 37 provided in the force application member 3 in the first embodiment. This second restrictive urging member may have a configuration similar to the force-limiting member 7. The second restrictive urging member is disposed between the second pressing portion 63f corresponding to the second abutting portion 63b of the drive roller 172 in the first embodiment and the second rotation stopper end portion 35b of the force application member 3 in the rotation direction of the drive roller 172.

[0089] [Example 3] Next, another embodiment of the present invention will be described. The basic configuration and operation of the image forming apparatus of this embodiment are the same as those of the image forming apparatus of embodiment 1. Therefore, in the image forming apparatus of this embodiment, elements having the same or corresponding functions or configurations as those of the image forming apparatus of embodiment 1 are assigned the same reference numerals as those of embodiment 1, and detailed descriptions thereof will be omitted.

[0090] In this embodiment, the configurations of the regulating member 2 and the force applying member 3 in the distance adjusting mechanism 10 are different from those in the first embodiment.

[0091] FIG. 18 is an exploded perspective view illustrating the regulating member 2 and the force applying member 3 of the gap adjustment mechanism 10 in this embodiment. FIG. 19 is a diagram illustrating the gap adjustment mechanism 10 in a separated state (the state of the image forming apparatus 100 at the time of shipment) (the intermediate transfer belt 171 is not shown). FIG. 19(a) is a side view of the vicinity of the drive side end of the drive roller 172 and the secondary transfer roller 109 as viewed in the -Z direction. FIG. 19(b) is a cross-sectional view taken along line AA in FIG. 19(a) (showing a cross-section perpendicular to the rotational axis of the drive roller 172). FIG. 19(c) is a cross-sectional view taken along line BB in FIG. 19(a) (showing a cross-section perpendicular to the rotational axis of the drive roller 172).

[0092] 18 and 19(b), in this embodiment, a restricting and biasing portion 26 corresponding to the restricting and biasing portion 36 provided on the force application member 3 in Example 1 is provided on the restricting member 2. Furthermore, in this embodiment, a biasing force receiving portion 39a corresponding to the biasing force receiving portion 63e provided on the drive roller 172 in Example 1 is provided on the force application member 3. Similar to that in Example 1, the restricting and biasing portion 26 provided on the restricting member 2 has a flexible plate-shaped base portion 26b and a restricting action portion 26a provided on the end of the base portion 26b on the force application member 3 side. The base portion 26b is configured to be deformable in a direction along the rotation direction of the drive roller 172. Furthermore, the restricting action portion 26a is able to come into contact with the biasing force receiving portion 39a provided on the force application member 3. In this embodiment, the restricting and biasing portion 26 restricts the relative position (relative phase) of the force applying member 3 to the restricting member 2 in the rotation direction of the drive roller 172 when the drive roller 172 stops rotating.

[0093] 19(a), the gap adjustment mechanism 10 is configured so that the force application portion 31 of the force application member 3 has a degree of freedom of rotation in the direction C (idling area G) relative to the force receiving portion 21 of the regulation member 2 when the regulation urging portion 26 comes into contact with the urging receiving portion 39a. That is, in this embodiment, before the image forming apparatus 100 is shipped, the force application member 3 is stopped in such a manner that the force receiving portion 21 of the regulation member 2 precedes the force application portion 31 of the force application member 3 in the direction C.

[0094] 19(b), the force application member 3 may be attached to the drive roller 172 with the first rotation stop end 35a abutting against the first abutment portion 63a. Similarly, the force application member 3 may be attached to the drive roller 172 with the second rotation stop end 35b abutting against the second abutment portion 63b. However, the force application member 3 may also be attached to the drive roller 172 with the first rotation stop end 35a and the second rotation stop end 35b not abutting against the first abutment portion 63a and the second abutment portion 63b, respectively.

[0095] As a result, when the secondary transfer bearing 4 receives a logistics impact in the -Z direction, the regulating member 2 is able to rotate in the -C direction within the range of the above-mentioned degree of freedom of rotation (idling region G) by deforming the regulating biasing portion 26. As a result, the regulating member 2 does not receive force from the force application member 3, and does not move translationally in the Y direction relative to the force application member 3. Therefore, even if the secondary transfer bearing 4 receives a logistics impact in the -Z direction, the secondary transfer bearing 4 does not fall between the regulating member 2 and the force application member 3, and the separated state is maintained.

[0096] Even with this configuration, an idling area G that acts similarly to the idling area E in the first embodiment is provided, and it is possible to prevent the regulating member 2 from disengaging from the secondary transfer bearing 4 even when subjected to a physical distribution shock. This makes it possible to stably maintain the separation state between the secondary transfer roller 109 and the intermediate transfer belt 171 and the drive roller 172.

[0097] As described above, in this embodiment, the force applying member 3 has a rotational force receiving portion (first rotation stop end portion) 35a that receives a force from the rotating body 172 that rotates the force applying member 3 in a predetermined rotation direction of the rotating body 172, and a biasing receiving portion 39a that abuts against the position restricting portion (restricting biasing portion) 26, the rotating body 172 has a rotational force applying portion (abutting portion) 63a that applies a force that rotates the force applying member 3 in the predetermined rotation direction to the rotational force receiving portion 35a, and the position restricting portion 26 is provided on the restricting member 2, and the biasing receiving portion 39a abuts against the position restricting portion 26. By abutting against 39a, the relative position of the force applying member 3 with respect to the regulating member 2 in the predetermined rotation direction when the rotation of the rotating body 172 stops is restricted to a position where the force receiving portion 21 precedes the force applying portion 31 in the predetermined rotation direction, and the position restricting portion 2 abuts against the biasing force receiving portion 39a during the period from when the rotating body 172 starts to rotate in the predetermined rotation direction until the force applying portion 31 abuts against the force receiving portion 21, and is elastically deformed in accordance with the rotation of the rotating body 172 in the predetermined rotation direction. Also, in this embodiment, the rotational force receiving portion 35a abuts against the rotational force applying portion 63a when the rotation of the rotating body 172 stops.

[0098] 18 and 19(b), a second restrictive urging portion 27 corresponding to the second restrictive urging portion 37 provided on the force applying member 3 in the first embodiment may be provided on the restricting member 2. In this case, a second urging force receiving portion 39b corresponding to the second urging force receiving portion 63d provided on the drive roller 172 in the first embodiment is provided on the force applying member 3. This makes it possible to obtain the same effect as that obtained by the second restrictive urging portion 37 in the first embodiment.

[0099] [others] Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-described embodiments.

[0100] In the above-described embodiment, the gap adjustment mechanism adjusts the gap between the rotation shaft of the drive roller that stretches the intermediate transfer belt and the secondary transfer bearing as an opposing member. However, the present invention is not limited to this embodiment. The gap adjustment mechanism may also adjust the gap between other rotation shafts and opposing members. For example, the gap adjustment mechanism may adjust the gap between the rotation shaft of an image carrier (such as a photosensitive drum) and a support member that supports a transfer member (such as a transfer roller) in a direct transfer image forming apparatus. Furthermore, the gap adjustment mechanism may adjust the gap between the rotation shaft of an image carrier (such as a photosensitive drum) and a support member that supports a primary transfer member (such as a primary transfer roller) in an intermediate transfer image forming apparatus. Furthermore, the gap adjustment mechanism may adjust the gap between the rotation shaft of an image carrier (such as a photosensitive drum) and a support member that supports a charging member (such as a charging roller). Furthermore, for example, the gap adjustment mechanism may be one that adjusts the gap between the rotation shaft of an image carrier (such as a photosensitive drum) and a support member that supports a developing member (such as a developing roller).

[0101] In the above-described embodiment, the gap adjustment mechanism adjusts the gap between the rotating shaft of the rotating body and the opposing member to change the state of contact or separation between the rotating body and the member that can contact it (the second rotating body), but the present invention is not limited to this.The gap adjustment mechanism may adjust the gap between the rotating shaft of the rotating body and the opposing member to change the contact pressure between the rotating body and the member that can contact it (the second rotating body) between a first contact and a second contact pressure that is smaller than the first contact pressure.

[0102] In the above-described embodiment, the rotational force imparting portion and the biasing receiving portion are respectively formed on the side surfaces of the roller rib portion of the three-arrow tube that constitutes the core metal of the roller, but are not limited to this and may be, for example, protrusions provided on the end surfaces of the roller portion of the roller.

[0103] In the above embodiment, the groove of the regulating member and the protrusion of the opposing member are in a disengaged state when the image forming apparatus is shipped, but the groove of the regulating member and the protrusion of the opposing member may be in an engaged state when the image forming apparatus is shipped. Even in this case, according to the present invention, it is possible to prevent the gap between the rotating shaft and the opposing member from changing due to shock during transportation, etc.

[0104] In the above-described embodiment, the opposing member is configured as a support member that rotatably supports the second rotating body (secondary transfer roller) that faces the rotating body, but the present invention is not limited to such a configuration. For example, the opposing member may be configured as a member attached to the rotation shaft of the second rotating body, separate from the support member that rotatably supports the second rotating body (secondary transfer roller, etc.) that faces the rotating body.

[0105] In the above-described embodiment, the regulating member is attached to the rotating shaft by being attached to the outer peripheral surface of the force-applying member, but this is not limited to this, and the regulating member may also be attached directly to the outer peripheral surface of the rotating shaft. [Explanation of symbols]

[0106] 1 Rotation axis 2. Regulatory elements 3 Force applying member 4 Secondary transfer bearing (opposing member) 5 Secondary transfer spring (biasing member) 6 Core 21 Force receiving part 31 Force applying section 35 Rotation stopper 35a First rotation stop end (rotational force receiving portion) 36 Restriction biasing portion (position restriction portion) 63a Abutment part (rotational force applying part) 63c Force receiving portion 100 Image forming device 109 Secondary transfer roller 171 Intermediate transfer belt 172 Drive roller

Claims

1. In an image forming apparatus, a gap adjustment mechanism for adjusting a gap between a rotation shaft of a rotating body and an opposing member disposed opposite the rotation shaft, a biasing member that biases the opposing member toward the rotation shaft; a restricting member that restricts the distance and is movably attached to the rotation shaft; a force applying member attached to the rotation shaft so as to be rotatable in conjunction with the rotation of the rotating body in a predetermined rotation direction, the force applying member including a force applying portion that applies a force to the regulating member to move the regulating member; an elastically deformable position restricting portion that restricts the position of the force applying member; and the regulating member is a force receiving portion that receives a force from the force applying member that rotates in the predetermined rotational direction in conjunction with the rotation of the rotating body in the predetermined rotational direction, and is configured to receive a force including a component force that acts from the force applying portion in the rotational axis direction of the rotating body due to relative movement between the regulating member and the force applying member, and is movable due to rotation of the force applying member in the predetermined rotational direction from a first position at which the regulating member applies a biasing force of the biasing member so that the gap becomes a predetermined gap, to a second position that is different from the first position in the rotational axis direction and where the manner in which the regulating member applies the biasing force changes relative to the first position, a position regulating unit configured to regulate the position of the force applying member in the predetermined rotation direction when the rotation of the rotating body is stopped, and to be elastically deformed in accordance with the rotation of the rotating body in the predetermined rotation direction during the period from when the rotating body starts to rotate in the predetermined rotation direction until when the regulating member starts to move from the first position to the second position when the force applying member rotates in the predetermined rotation direction in conjunction with the rotation of the rotating body in the predetermined rotation direction and the regulating member moves from the first position to the second position.

2. the force application member has a rotational force receiving portion that receives a force from the rotating body that rotates the force application member in the predetermined rotational direction, the rotating body has a rotational force applying portion that abuts against the rotational force receiving portion and applies a force to the force applying member that rotates the force applying member in the predetermined rotational direction, and a biasing force receiving portion that abuts against the position restricting portion, the position regulating portion is provided on the force applying member and abuts against the bias receiving portion, thereby regulating the relative position of the force applying member with respect to the rotating body in the predetermined rotation direction when the rotation of the rotating body is stopped to a position where the rotational force receiving portion precedes the rotational force applying portion in the predetermined rotation direction; The spacing adjustment mechanism described in claim 1, characterized in that the position regulating portion abuts against the bias receiving portion between the time when the rotating body starts to rotate in the predetermined rotation direction and the time when the rotational force applying portion abuts against the rotational force receiving portion, and is elastically deformed as the rotating body rotates in the predetermined rotation direction.

3. the force application member has a rotational force receiving portion that receives a force from the rotating body that rotates the force application member in the predetermined rotational direction, the rotating body has a rotational force applying portion that applies a force to the rotational force receiving portion to rotate the force applying member in the predetermined rotational direction, the position regulating portion is composed of an elastic member arranged so as to be sandwiched between the rotational force applying portion and the rotational force receiving portion in the predetermined rotation direction, and regulates the relative position of the force applying member with respect to the rotating body in the predetermined rotation direction when the rotation of the rotating body is stopped to a position where the rotational force receiving portion precedes the rotational force applying portion in the predetermined rotation direction; The spacing adjustment mechanism described in claim 1, characterized in that the position regulating portion transmits the force that rotates the force applying member in the predetermined rotational direction from the rotational force applying portion to the rotational force receiving portion in a state where it is compressed and elastically deformed between the rotational force applying portion and the rotational force receiving portion as the rotating body rotates in the predetermined rotational direction.

4. the force application member has a rotational force receiving portion that receives a force from the rotating body that rotates the force application member in the predetermined rotational direction, and an urging force receiving portion that abuts against the position regulating portion, the rotating body has a rotational force applying portion that applies a force to the rotational force receiving portion to rotate the force applying member in the predetermined rotational direction, the position regulating portion is provided on the regulating member, and by abutting against the bias receiving portion, regulates the relative position of the force applying member with respect to the regulating member in the predetermined rotation direction when the rotation of the rotating body is stopped to a position where the force receiving portion precedes the force applying portion in the predetermined rotation direction; The gap adjustment mechanism according to claim 1, characterized in that the position regulating portion abuts against the bias receiving portion between the time when the rotating body starts to rotate in the predetermined rotation direction and the time when the force applying portion abuts against the force receiving portion, and is elastically deformed in accordance with the rotation of the rotating body in the predetermined rotation direction.

5. 5. The gap adjusting mechanism according to claim 4, wherein the rotational force receiving portion abuts against the rotational force applying portion when the rotating body is stopped from rotating.

6. a second position restriction portion that is elastically deformable and restricts the position of the force application member; The gap adjustment mechanism according to claim 1, characterized in that the second position regulating portion regulates the position of the force applying member in the predetermined rotation direction when the rotation of the rotating body is stopped, and is configured to be elastically deformed in association with the rotation of the rotating body in the opposite direction to the predetermined rotation direction when the rotating body rotates in the opposite direction.

7. the rotating body has a roller portion and the rotation shaft protruding from an end of the roller portion in the direction of the rotation axis, 2. The gap adjustment mechanism according to claim 1, wherein the force application member has a contact portion that contacts an end face of the roller portion in the direction of the rotation axis and has an outer diameter smaller than an outer diameter of the roller portion.

8. the first position is a position where the regulating member exerts a force against the biasing force so that the gap becomes a predetermined gap, 2. The gap adjusting mechanism according to claim 1, wherein the second position is a position where the restricting member does not exert a force that resists the biasing force.

9. the first position is a position where the regulating member is sandwiched between the rotation shaft and the opposing member, 2. The gap adjusting mechanism according to claim 1, wherein the second position is a position where the restricting member is not sandwiched between the rotary shaft and the opposing member.

10. When the regulating member is in the first position, the gap is regulated to a first gap, 2. The gap adjusting mechanism according to claim 1, wherein when the restricting member is in the second position, the gap becomes a second gap that is narrower than the first gap.

11. the force receiving portion is a surface extending obliquely with respect to the predetermined rotation direction and the rotation axis direction, 2. The gap adjusting mechanism according to claim 1, wherein the force applying portion is a protrusion that abuts against the surface.

12. 2. The distance adjustment mechanism according to claim 1, further comprising a guide portion that restricts movement of the regulating member so that relative movement occurs between the regulating member and the force application member, and that guides the regulating member from the first position to the second position.

13. the guide portion is provided in the regulating member and includes a groove portion extending in the rotation axis direction, and a protrusion portion provided in the opposing member and engageable with the groove portion, The gap adjustment mechanism according to claim 12, characterized in that the restricting member restricts movement of the rotating body around the rotation axis while allowing movement in the direction of the rotation axis by engaging the protrusion with the groove.

14. the restricting member and the force applying member are each annular members, the force applying member is attached to an outer circumferential surface of the rotating shaft, 2. The gap adjusting mechanism according to claim 1, wherein the regulating member is attached to an outer peripheral surface of the force applying member.

15. 2. The gap adjustment mechanism according to claim 1, wherein the first position is closer to the center of the rotating body in the direction of the rotation axis than the second position.

16. 2. The gap adjusting mechanism according to claim 1, wherein the restricting member and the force applying member are provided on both end sides of the rotating body in the direction of the rotation axis, respectively.

17. 2. The gap adjustment mechanism according to claim 1, wherein the opposing member is a support member that rotatably supports the second rotating body and is provided so as to be movable toward and away from the rotation axis.

18. the rotating body is a roller around which a belt carrying a toner image is stretched, The gap adjustment mechanism according to claim 17, wherein the second rotating body is a roller that contacts the rotating body via the belt when the regulating member is in the second position, and forms a transfer section for transferring a toner image from the belt to a recording material.

19. 19. The gap adjustment mechanism according to claim 18, wherein the second rotating body is spaced apart from the belt when the regulating member is in the first position.

20. a rotating body having a rotation axis; an opposing member disposed opposite the rotation shaft; A gap adjustment mechanism according to any one of claims 1 to 19; An image forming apparatus comprising:

Images