JP7775346B2 - Gap adjustment mechanism and image forming apparatus - Google Patents

Description

The present invention relates to a gap adjustment mechanism for an image forming device such as a copying machine, printer, or facsimile machine that uses an electrophotographic or electrostatic recording method, or a multifunction device that has multiple functions among these, and to an image forming device equipped with the same.

Conventional image forming devices using electrophotography and other technologies include direct transfer devices, in which a toner image formed on an image carrier is directly transferred to a transfer material such as paper, and intermediate transfer devices, 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 devices use a transfer member that contacts the image carrier to form a transfer nip, and the toner image on the image carrier is transferred to the transfer material as it passes through the transfer nip. Intermediate transfer image forming devices use 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 to the intermediate transfer belt at the primary transfer nip. A secondary transfer member that contacts the intermediate transfer belt's tension roller via the intermediate transfer belt to form a secondary transfer nip is also used, and the toner image on the intermediate transfer belt is secondarily transferred to the transfer material as it passes through the secondary transfer nip. Rotatable rollers and 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).

The transfer nip is formed when the image carrier or intermediate transfer belt and the transfer member are 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 when shipping an image forming apparatus, the elastic material that makes up the transfer member may undergo plastic deformation due to heat or other factors. If the elastic material that makes up the transfer member undergoes plastic deformation, the transfer nip may no longer receive sufficient contact pressure, potentially resulting in poor transfer. Furthermore, in image forming devices that use an intermediate transfer method, 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, which can lead to poor transfer.

In response to this, Patent Document 1 discloses a gap adjustment mechanism that, for example, ships an image forming apparatus with the secondary transfer member separated from the intermediate transfer belt, and automatically brings 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 the opposing member moves in the axial direction of the rotating shaft in conjunction with the rotational movement of the rotating shaft, changing the gap between the rotating shaft and the opposing member.

JP 2016-114649 A

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 secondary transfer member losing their separation state and coming into contact with each other. For this reason, it may be necessary to use more extensive packaging to reduce shipping shock so that the separation state can be maintained even during the anticipated shipping of the image forming device.

The 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 changing due to external forces such as impacts during logistics.

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

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 disposed opposite the rotating shaft, and the above-described gap adjustment mechanism of the present invention.

This invention makes it possible to prevent the gap between the rotating shaft and the opposing member, which is adjusted by the gap adjustment mechanism, from changing due to external forces such as impacts during logistics.

FIG. 1 is a schematic perspective view of an image forming apparatus. FIG. 1 is a schematic cross-sectional view of an image forming apparatus. FIG. 2 is a schematic cross-sectional view of an image forming unit. FIG. 4 is a side view illustrating a support structure for a drive roller and a secondary transfer roller. FIG. 10 is a perspective view illustrating components of a gap adjustment mechanism of a comparative example. 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. 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. 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. 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. FIG. 2 is a perspective view of a force applying member that constitutes the gap adjusting mechanism of the first embodiment. 4A and 4B are side views and a cross-sectional view for explaining the operation of the gap adjustment mechanism of the first embodiment. 4A and 4B are side views and a cross-sectional view for explaining the operation of the gap adjustment mechanism of the first embodiment. 4A and 4B are side views and a cross-sectional view for explaining the operation of the gap adjustment mechanism of the first embodiment. 10A and 10B 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. FIG. 14( c ) is an enlarged view of a portion of FIG. FIG. 10 is a perspective view showing a comparison of the force applying members of a comparative example and Example 1. 10A and 10B are a side view and a cross-sectional view for explaining a gap adjustment mechanism of a second embodiment. FIG. 11 is a perspective view of a regulating member and a force applying member that constitute a gap adjusting mechanism according to a third embodiment. 11A and 11B are side views and a cross-sectional view for explaining the operation of the gap adjustment mechanism of the third embodiment.

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

[Example 1]
1. Configuration of Image Forming Apparatus Fig. 1 is a schematic perspective view of the exterior of an image forming apparatus 100 according to 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 according to this embodiment.

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 has four image forming units PY, PM, PC, and PK, which form images using toner of the respective colors: 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 equipped with a process cartridge 108Y, 108M, 108C, or 108K that is detachable from the main body 110 of the image forming apparatus 100. The process cartridges 108Y, 108M, 108C, or 108K can be removed from or installed in the main body 110 with the door 111 provided on 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.

The four image forming units PY, PM, PC, and PK are arranged in a row at regular intervals. In this embodiment, the configuration of each image forming unit PY, PM, PC, and PK is essentially the same, except for the different colors of toner contained in the developing device 104, which will be described later. Elements with 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.

With regard to the image forming apparatus 100 and its components, the right side of the page in FIG. 2 (the side where the door 111 is located) is referred to as the "front (front) side," and the left side (opposite the front side) is referred to as the "rear (back) side." Furthermore, 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 the driving force is input in the direction of the rotational axis 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 of the photosensitive drum 101 and the drive roller 172. The direction from the rear side to the front side of the device body 110 is referred to as the "X direction," the direction from the non-drive side toward 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 device body 110, which is perpendicular to the X and Y directions, is referred to as the "Z direction." Additionally, the direction opposite the X direction (or +X direction), the direction opposite the Y direction (or +Y direction), and the direction opposite the Z direction (or +Z direction) are also referred to as the "-X direction," "-Y direction," and "-Z direction," respectively. It is assumed that image forming device 100 will be used while positioned so that the X direction and Y direction are both approximately horizontal. Furthermore, with regard to image forming device 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 just directly above or directly below, and also includes the above and below of a horizontal plane passing through the element or position of interest.

The four image forming units PY, PM, PC, and PK are arranged in a row, approximately horizontally, on the bottom surface of the device main body 110. The image forming units 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 rotational drive 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.

An intermediate transfer unit 107 is provided below each process cartridge 108. The intermediate transfer unit 107 is composed of an intermediate transfer belt 171, four primary transfer rollers 106Y, 106M, 106C, and 106K, tension rollers 172, 173, and 174 for the intermediate transfer belt 171, a toner charging brush 175, and a frame 176. The intermediate transfer belt 171 is an intermediate transfer body composed 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. The drive roller 172 receives driving force from a belt drive unit (not shown) provided in the device main body 110, and rotates in the clockwise direction in FIG. 2. As a result, the intermediate transfer belt 171 receives a driving force from the drive roller 172 and rotates (circularly moves) in the direction of arrow R2 (clockwise) in Figures 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 unit N2, which will be described later. The toner charging brush 175 charges the toner on the intermediate transfer belt 171 so that it can be collected by the cleaning device 105 of the process cartridge 108.

On the inner surface 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 respective photosensitive drums 101Y, 101M, 101C, and 101K. The primary transfer rollers 106 extend along the Y direction and contact the inner 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 a primary transfer portion (primary transfer nip) N1 where the photosensitive drums 101 and the intermediate transfer belt 171 come into contact. In this embodiment, each primary transfer roller 106 is positioned offset from the position of the respective primary transfer portion N1 where the respective photosensitive drums 101 and the intermediate transfer belt 171 come into contact. More specifically, in this embodiment, each primary transfer roller 106 is positioned downstream of 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 positioned upstream of 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.

A secondary transfer roller 109, a roller-type secondary transfer member serving as a secondary transfer means, is disposed on the outer peripheral surface of the intermediate transfer belt 171, facing the drive roller 172 across the intermediate transfer belt 171. The secondary transfer roller 109 extends along the Y direction and contacts the outer peripheral 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 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.

Upstream of the secondary transfer unit N2 in the transport direction of the transfer material S, there are provided a feeding device 120 as a feeding means, a pair of registration rollers 112 as a transport means, and the like. The feeding device 120 is composed of a cassette 51 as a transfer material storage unit that stores the transfer material S, and a feeding roller 52 as a feeding member that feeds the transfer material S from the cassette 51. Further, downstream of the secondary transfer unit N2 in the movement direction of the transfer material S, there are provided a fixing device 113 as a fixing means, a pair of discharge rollers 114 as a discharge transport means, and the like. Furthermore, a tray 115 as a stacking unit is provided on the top surface of the device main body 110.

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, and a memory (not shown) as a storage means in which various control information is stored. The controller controls the transport of the transfer material S, controls the driving of the intermediate transfer belt 171 and each image forming station P, and controls image formation.

2. Image Forming Operation Next, the image forming operation of the image forming apparatus 100 of this embodiment will be described.

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

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 the charging roller 102, a roller-type charging member that serves as a charging means. The charging roller 102 is positioned 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.

The surface of the charged photosensitive drum 101 is scanned and exposed by the exposure device 103, which serves as an exposure means, in accordance with image information, forming an electrostatic latent image (electrostatic image) on the photosensitive drum 101. The exposure device 103 outputs laser light corresponding to the image information received by the controller. The laser light output from the exposure device 103 passes through an exposure window in the 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 for the image components of the colors corresponding to each image forming section PY, PM, PC, and PK.

The electrostatic latent image formed on the photosensitive drum 101 is developed (visualized) by the developing device 104, which serves as a developing means, by supplying toner as 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 composed of a developing roller 141, which serves as a developer carrier (developing member), and a developing container 142 that contains toner. The developing device 104 carries toner from the developing container 142 on the developing roller 141 and transports it to the 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 single-component developer (toner) as the developer. Furthermore, 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 development devices 104 of each image forming unit PY, PM, PC, and PK contain toner of each color: yellow, magenta, cyan, and black, respectively.

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

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 the transfer material S, which is sandwiched and transported between the intermediate transfer belt 171 and the secondary transfer roller 109. During 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). Alternatively, a secondary transfer voltage of the same polarity as the normal charging polarity of the toner may be applied to the 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 overhead projector sheets, is stored in a cassette 121. The transfer material S stored in the cassette 121 is fed from the cassette 121 by a feed roller 122 or the like at a predetermined timing. After the transfer material S has been corrected for skew by the registration roller 112, it is transported toward the secondary transfer unit N2 in time with the toner image on the intermediate transfer belt 171.

The transfer material S, onto which the toner image has been transferred at the secondary transfer section N2, is transported to the fixing device 113. The fixing device 113 applies heat and pressure to the transfer material S bearing the unfixed toner image, melting (mixing colors) the toner image and fixing it onto the transfer material S. The transfer material S with the fixed toner image is then ejected from the device main body 110 by a pair of ejection rollers 114 or the like, and loaded onto a tray 115.

In addition, toner remaining on the photosensitive drum 101 after primary transfer (primary transfer residual toner) is removed and collected from the photosensitive drum 101 by a cleaning device 105 serving as a cleaning means. The cleaning device 105 is composed of a cleaning blade 151 as a cleaning member positioned in contact with the surface of the photosensitive drum 101, a cleaning container 152 that contains toner removed from the surface of the photosensitive drum 101, and other components. The cleaning device 105 uses the cleaning blade 151 to scrape primary transfer residual toner from the surface of the rotating photosensitive drum 101 and collects it in a cleaning container 152. In addition, deposits such as toner remaining on the intermediate transfer belt 171 after 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) 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 unit 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 adhering matter from the intermediate transfer belt 171 using a cleaning member such as a cleaning blade may be provided as the belt cleaning means.

3. Supporting Structure of the Drive Roller and Secondary Transfer Roller Next, the supporting structure of the drive roller 172 and the secondary transfer roller 109 will be described.

Figure 4 is a side view of the vicinity of the drive roller 172 and secondary transfer roller 109 as viewed in the -Z direction (the intermediate transfer belt 171 is not shown). Figure 4(a) shows a state in which the secondary transfer roller 109 is in contact with the intermediate transfer belt 171 and drive roller 172 (also referred to here simply as the "contact state"). Figure 4(b) shows a state in which the secondary transfer roller 109 is spaced apart from the intermediate transfer belt 171 and drive roller 172 (also referred to here simply as the "spaced apart state"). During image formation, the secondary transfer roller 109 is in contact with the intermediate transfer belt 171 and drive roller 172 as shown in Figure 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 drive roller 172 as shown in Figure 4(b).

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 composed of 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 direction of its rotation axis, 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 on a frame 176 of the intermediate transfer unit 107. The secondary transfer roller 109 is positioned 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 composed of 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 apparatus 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 formed of a compression coil spring and serves as a biasing member for biasing the opposing member. 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 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 to be able to move linearly in the -X direction against the biasing force of the secondary transfer spring 5. In addition, 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 direction of its rotation axis.

In the image formation state (contact state) shown in FIG. 4(a), the secondary transfer bearing 4 is biased by the secondary transfer spring 5, 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 wrapped around the drive roller 172, forming the secondary transfer nip N2. In the image formation state, 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.

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 drive roller 172. As described in detail below, 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 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 factors such as 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.

4. Separation Structure of Secondary Transfer Roller Next, the separation structure (gap adjustment mechanism) of the secondary transfer roller 109 will be described.

<Configuration of gap adjustment mechanism of 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.

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 of the secondary transfer roller 109 in the direction of the rotation axis. The configuration of the components at both ends is essentially the same (substantially symmetrical with respect to a plane that passes through the center of the secondary transfer roller 109 in the direction of the rotation axis and is perpendicular to the rotation axis). Therefore, the following description will focus on the configuration on the drive side.

Figure 5 is an exploded perspective view illustrating the components of the gap adjustment mechanism 10 of the comparative example. In Figure 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. Figure 6 is a diagram illustrating the gap adjustment mechanism 10 in the separated state (the state at the time of shipment of the image forming apparatus 100). Figure 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, viewed in the -Z direction. Figure 6(b) is a cross-sectional view taken along A-A in Figure 6(a) (showing a cross-section perpendicular to the rotational axis of the drive roller 172). Figure 6(c) is a cross-sectional view taken along B-B in Figure 6(a) (showing a cross-section perpendicular to the rotational axis of the drive roller 172). Figure 7 is a similar view to Figure 6 to illustrate the gap adjustment mechanism 10 in the process of transitioning from the separated state (Figure 6) to the abutting state (Figure 8). FIG. 8 is a diagram similar to FIG. 6, illustrating the gap adjustment mechanism 10 in a contact state (state during image formation). The intermediate transfer belt 171 is omitted from 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."

A regulating member 2 is disposed on the rotating 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 (regulating the distance between the rotating shaft 1 and the secondary transfer bearing 4). The regulating member 2 is an annular member, and its inner peripheral surface 24 contacts the outer peripheral surface 33 of the force application member 3, which will be described later. The regulating member 2 is attached to the force application member 3 so as to be rotatable in the rotational direction of the drive roller 172 and movable in translation along the rotational axis of the drive roller 172. The regulating member 2 has a force receiving portion 21 adjacent to the inner peripheral surface 24 that contacts the outer peripheral surface 33 of the force application member 3, and which contacts the force application portion 31 of the force application member 3, which will be described later. The force receiving portion 21 is configured as a surface (inclined surface) that extends obliquely relative to the rotational direction of the drive roller 172 and the rotational axis of the drive roller 172. The regulating member 2 also has a groove 22 (an engagement recess constituting a guide portion) on its outer surface 23, which is in contact with the secondary transfer bearing 4, and which can engage with a protrusion 42 (described later) of the secondary transfer bearing 4. The regulating member 2 is disposed concentrically with the rotation axis 1 of the drive roller 172.

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 has a force application portion 31 on its outer peripheral surface 33, which contacts the inner peripheral surface 24 of the regulating member 2, that contacts the force receiving portion 21 of the regulating member 2. The force application portion 31 is composed of a protrusion provided on the outer peripheral surface 33 of the force application member 3 so as to protrude radially from the drive roller 172. The force application member 3 is arranged concentrically with the rotation axis 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 application member 3.

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 of the drive roller 172 in the direction of its rotational axis. In other words, a rotating shaft 1 is provided at one end of the drive roller 172 in the direction of its rotational axis. The force applying member 3 is provided so that the outer peripheral surface of this rotating shaft 1 contacts (substantially mates with) the inner peripheral surface 32 of the force applying member 3. The regulating member 2 is then provided outside the force applying member 3 so that the outer peripheral surface 33 of the force applying member 3 contacts (substantially mates with) the inner peripheral surface 24 of the regulating member 2. The rotating shaft 1, force applying member 3, and regulating member 2 of the drive roller 172 are configured concentrically.

In this example, the core 6 that constitutes the roller portion 172a of the drive roller 172 is composed of a three-arrow pipe, and a rotating shaft (shaft member) 1 is fixed to both ends of this core 6 in the direction of the rotational 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 that are provided radially connecting the inner tube portion 61 and the outer tube portion 62. The force applying member 3 has a rotation stopper portion 35 on its end surface 34 that faces the roller portion 172a of the drive roller 172 in the direction of the rotational axis of the drive roller 172. The rotation stopper portion 35 is provided to protrude in the direction of the rotational axis of the drive roller 172 so as to enter the inside of the roller portion 172a of the drive roller 172. The rotation stopper portion 35 is composed 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 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 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 with the first rotation stop end 35a abutting 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 with the second rotation stop end 35b also abutting against the second abutment portion 63b of the drive roller 172. Therefore, in the comparative example, the force application member 3 is configured to rotate substantially integrally with the drive roller 172.

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 42 (an engaging protrusion constituting a guide portion) that protrudes toward the drive roller 172 and can engage with the groove portion 22 of the regulating member 2 (Figure 6(c)).

The regulating member 2, force applying member 3, and secondary transfer bearing 4 are made of synthetic resin, and the core 6 of the drive roller 172 is made of metal (this is also the case in this embodiment, which will be described later).

<Contact Operation of Gap Adjustment Mechanism of 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 comparative example, which is changed from the state at the time of shipment to the state during image formation, will be described with reference to FIGS.

Figure 6 shows the state of the image forming apparatus 100 at the time of shipment, with the secondary transfer roller 109 separated from the intermediate transfer belt 171 and the drive roller 172. As shown in Figure 6(a), the regulating member 2 is provided with a sloped force receiving portion 21. 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 movable in translation along the rotation axis 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 Figure 6(b), the force applying member 3 is in a state in which the first rotation stop end 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 image forming apparatus 100 is shipped, 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 abutting against the first abutment portion 63a of the drive roller 172. Note that in this example, as described above, before the image forming apparatus 100 is shipped, the second rotation stop end 35b of the force applying member 3 also abuts against 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.

Figure 7 shows a state during contact operation in which the drive roller 172 has rotated in direction C from the state shown in Figure 6 as the image forming apparatus 100 begins to operate. As shown in Figure 7(b), as the drive roller 172 rotates in direction C, the force application member 3 rotates in conjunction with it in direction C. As shown in Figure 7(c), as the drive roller 172 and force application member 3 rotate in direction C, the regulating member 2 also rotates in conjunction with it in direction C. The regulating member 2 rotates in conjunction with the force application member 3 due to, for example, the force application portion 31 of the force application member 3 contacting the force receiving portion 21 (or friction at other contact points between the regulating member 2 and the force application member 3). The protrusion 42 of the secondary transfer bearing 4 then engages with the groove 22 of the regulating member 2. When the drive roller 172 continues to rotate with these two engaged, rotation of the regulating member 2 in direction C 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 direction C (movement in the X direction in Figure 7(a)), the regulating member 2 translates in direction Y (from the center toward the end in the direction of the rotation axis of the drive roller 172).

Figure 8 shows the state during image formation in which the drive roller 172 has further rotated in the C direction from the state shown in Figure 7, and the secondary transfer roller 109 has come into contact with the intermediate transfer belt 171 and drive roller 172. As shown in Figure 8(a), the regulating member 2 further translates in the Y direction from the state shown in Figure 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 Figures 8(a) and (b), the secondary transfer roller 109 transitions to a contact state in which it comes into contact with the intermediate transfer belt 171 and drive roller 172.

After the regulating member 2 disengages from the secondary transfer bearing 4, it continues to rotate in conjunction with the drive roller 172 due to the force application portion 31 of the force application member 3 contacting the force receiving portion 21 (or friction at other contact points between the regulating member 2 and the force application member 3). To change from a contact state to a 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, to position the regulating member 2 in contact with the secondary transfer bearing 4.

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 arranged opposite it, thereby adjusting the gap (separation, abutment) between the secondary transfer roller 109 and the intermediate transfer belt 171. The gap adjustment mechanism 10 is composed of 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, which rotates in conjunction with the drive roller 172.

When the secondary transfer roller 109, intermediate transfer belt 171, and drive roller 172 are shifted from a separated state to a contact state, the regulating member 2 first rotates around the rotational axis of the drive roller 172, along 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 surface 23 of the regulating member 2, to engage (substantially mate) with the groove 22 formed on the outer surface 23 of the regulating member 2 and extending in the direction of the rotational axis of the drive roller 172. As a result, the rotation of the regulating member 2 is restricted, 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 groove 22 function as anti-rotation mechanisms that restrict the rotation of the regulating member 2 around the rotational axis of the drive roller 172. As a result, the regulating member 2 restricts rotation of the drive roller 172 around its rotation axis while allowing movement in the direction of the drive roller's rotation axis.

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 direction of the rotational axis 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 direction of the rotational axis of the drive roller 172. As a result, the regulating member 2 moves in the direction of the rotational axis of the drive roller 172, from the center toward the outside of the direction of the rotational axis 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 rotational axis 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. When the image forming apparatus 100 starts operating, the restricting 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 biasing force of the secondary transfer spring 5 changes from the first position; specifically, it moves to a position (second position) where it is not sandwiched between the rotation shaft 1 of the drive roller 172 and the secondary transfer bearing 4 and does not exert a force against the biasing force of the secondary transfer spring 5.

<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.

As shown in Figure 9(c), it is conceivable that the secondary transfer bearing 4 will be subjected to a shipping impact in the -Z direction while the protrusion 42 of the secondary transfer bearing 4 is 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.

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 application member 3 abuts against the first abutment portion 63a of the drive roller 172. Therefore, in response to the -Z direction force from the secondary transfer bearing 4, the force application member 3 has no degree of freedom to rotate (move) in the -C direction. Furthermore, because the drive roller 172 is connected to a drive source (not shown), it has no degree of freedom to rotate in the -C direction (nor in the C direction). Therefore, the regulating member 2, which receives a -Z direction force from the secondary transfer bearing 4, rotates in the -C direction (the -X direction in FIG. 9A) relative to the force application member 3 and drive roller 172, which have no degree of freedom to rotate in the -C direction. Furthermore, because the regulating member 2 is provided with a sloped force receiving portion 21, the force applying portion 31 of the force applying member 3 slides along the force receiving portion 21 as the regulating member 2 rotates, 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 abuts against the intermediate transfer belt 171 and the drive roller 172.

If the image forming device 100 transitions from a separated state to a contact state during transportation, the elastic body of the secondary transfer roller 109 and the intermediate transfer belt 171 may undergo plastic deformation due to the effects of heat during transportation of the image forming device 100. This may lead to image defects after the image forming device 100 arrives at its destination. Therefore, it may be necessary to use more extensive packaging to reduce logistics shocks and maintain the separated state even during anticipated transportation conditions of the image forming device 100.

<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 (the 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 A-A 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 B-B 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 (the 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.

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 application portion 31 is composed of a protrusion provided on the outer peripheral surface 33 of the force application member 3 so as to protrude radially from the drive roller 172. The force application member 3 is arranged concentrically with the rotation axis 1 of the drive roller 172 and the regulating member 2.

In this embodiment, as described above, the core 6 constituting the roller portion 172a of the drive roller 172 is constructed of a three-arrow pipe, and the rotary shaft (shaft member) 1 is fixed to the end of the core 6 in the direction of the rotational axis of the drive roller 172. The force applying member 3 has a rotation stopper 35 on its end surface 34 that faces the roller portion 172a of the drive roller 172 in the direction of the rotational axis of the drive roller 172. The rotation stopper 35 protrudes in the direction of the rotational axis of the drive roller 172 so as to enter the inside of the roller portion 172a of the drive roller 172. This rotation stopper 35 is constructed of a substantially arc-shaped rib (rib-shaped portion). The first rotation stopper end (rotational force receiving portion) 35a, which is the rear end of the rotation stopper 35 in direction C, can abut against the 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 direction C, 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. In the configuration of this embodiment, the extension angle of the rotation stopper 35 is smaller than that of the configuration of the comparative example (Ra > Rb). In the comparative example, the extension angle Ra of the rotation stopper 35 is approximately the same as the angle between the roller ribs 63 of the drive roller 172 (the angle in the rotation direction of the drive roller 172 between the side surfaces of adjacent roller ribs 63 centered on the rotation axis of the drive roller 172). In the present example, the extension angle Rb of the rotation stopper 35 is smaller than the angle between the roller ribs 63 of the drive roller 172.

In this embodiment, the force application member 3 further includes a flexible (elastically deformable) restricting and biasing portion 36 on the end face 34 facing the roller portion 172a of the drive roller 172 in the direction of the drive roller's rotation axis. In this embodiment, the restricting and biasing portion 36 restricts the relative position (relative phase) of the force application member 3 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 biasing 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 biasing portion 36 protrudes in the direction of the drive roller's rotation axis so as to enter inside the roller portion 172a of the drive roller 172. The restricting and biasing portion 36 includes a flexible, plate-shaped base portion 36b, one end of which is connected to the end face 34, and a restricting action portion 36a, which is provided at the other end of the base portion 36b. The base 36b is configured to be deformable in the direction along the rotational direction of the drive roller 172. The restricting portion 36a is also configured to be able to come into contact with the biasing portion 63c formed on the side of the roller rib portion 63 of the drive roller 172. In this embodiment, the restricting portion 36a is configured to be able to come into contact with the biasing portion 63c formed on the side of a roller rib portion 63 other than the two roller ribs 63 adjacent to the first rotation stop end 35a and the second rotation stop end 35b.

When the first rotation stop end 35a abuts against the abutment portion 63a of the drive roller 172, the force application member 3 can rotate in direction C in conjunction with the drive roller 172. At this time, the flexible restricting and biasing portion 36 abuts against the bias receiving portion 63c of the drive roller 172 and elastically deforms so as to tilt in direction C. Furthermore, when the drive roller 172 stops rotating, the restricting and biasing portion 36 abuts against the bias receiving portion 36c of the drive roller 172, thereby restricting the stopping position of the force application member 3 relative to the drive roller 172 in the rotational direction of the drive roller 172. Furthermore, when elastically deformed as described above, the restricting and biasing portion 36 uses its elastic restoring force to bias the force application member 3 to rotate relative to the drive roller 172 in a direction returning to the stopping position. As a result, in this embodiment, when the drive roller 172 stops rotating, the force application member 3 has a gap (idle region E) between the abutment portion 63a of the drive roller 172 and the first rotation stop end portion 35a of the force application member 3 in the rotation direction of the drive roller 172. The operation of the gap adjustment mechanism 10 in this embodiment will be described in detail later.

In this embodiment, the force applying member 3 further has a flexible (elastically deformable) second restricting urging portion 37 on the 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 second restricting urging portion 37 regulates the relative position (relative phase) of the force applying member 3 to the drive roller 172 in the direction of rotation of the drive roller 172 when the drive roller 172 stops rotating. The second restricting 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 restricting urging portion 37 is provided adjacent to the restricting urging portion (first restricting urging portion) 36 and has a configuration corresponding to the restricting urging portion 36. That is, the second restricting and biasing portion 37 has a flexible, plate-shaped base 37b with one end connected to the end surface 34 and a restricting action portion 37a provided at the other end of the base 37b. The base 37b is configured to be deformable in the direction of rotation of the drive roller 172. The restricting action portion 37a is configured to be able to abut against a second biasing receiving portion 63d formed on the side surface of the roller rib portion 63 of the drive roller 172. In this embodiment, the restricting action portion 37a of the second restricting and biasing portion 37 is configured to be able to abut against the second biasing 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 restricting action portion 36a of the restricting and biasing portion 36. However, the present invention is not limited to this configuration, and the second restricting and biasing portion 37 may not be provided. The function of the second restricting and biasing portion 37 will be described later.

<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) of the image forming apparatus 100 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.

Figure 11 shows the state of the image forming apparatus 100 at the time of shipment, with the secondary transfer roller 109 separated from the intermediate transfer belt 171 and the drive roller 172. As shown in Figure 11(a), the regulating member 2 is provided with a sloped force receiving portion 21. 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 movable in translation along the rotation axis 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 Figure 11(b), in this embodiment, prior to shipment of the image forming apparatus 100, the force applying member 3 is stopped with the first rotation stop end 35a preceding the abutment portion 63a of the drive roller 172 in direction C due to the regulating bias portion 36 contacting the bias 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 abutment portion 63a of the drive roller 172 and the first rotation stop end portion 35a of the force application member 3. For example, before shipment 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 restricting and urging portion 36 of the force application member 3 coming into contact with the urging 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 restricting and urging portion 36 and the second restricting and urging portion 37 are in contact with the urging receiving portion 63c and the second urging receiving portion 63d of the drive roller 172, respectively, before shipment of the image forming apparatus 100. In other words, the restricting and urging portion 36 and the second restricting and urging portion 37 may sandwich the roller rib portion 63 of the drive roller 172, thereby regulating 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 Figure 11(c), the secondary transfer bearing 4 is in a state where the protrusion 42 abuts against the outer circumferential surface 23 of the regulating member 2.

Figure 12 shows a state during contact operation in which the drive roller 172 rotates in direction C from the state shown in Figure 11 as the image forming apparatus 100 begins to operate. 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 direction C in conjunction with the rotation of the drive roller 172 in direction C. Furthermore, as the drive roller 172 and force applying member 3 rotate in direction C, the regulating member 2 also rotates in conjunction with the rotation of the drive roller 172 and force applying member 3 in 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 points between the regulating member 2 and the force applying member 3), etc. Then, as shown in Figure 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. Subsequently, 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 direction C (movement in the X direction in Figure 12(a)), the regulation member 2 begins to translate in direction Y (from the center toward the end in the direction of the rotation axis of the drive roller 172).

Figure 13 shows the state during image formation in which, after passing through the state in Figure 12, the regulating member 2 begins to move translationally as described above, and then the drive roller 172 further rotates in direction C, causing the secondary transfer roller 109 to abut against the intermediate transfer belt 171 and drive roller 172. As shown in Figure 13(a), as the regulating member 2 moves translationally in the Y direction from the state in Figure 12, the secondary transfer bearing 4, which was supported by the regulating member 2 and whose position in the X direction was regulated, falls between the regulating member 2 and the force application 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 Figures 13(a) and (b), the secondary transfer roller 109 transitions to a contact state in which it abuts against the intermediate transfer belt 171 and drive roller 172. Furthermore, as shown in Figure 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, where it stops.

After the regulating member 2 disengages from the secondary transfer bearing 4, it continues to rotate in conjunction with the drive roller 172 due to the force application portion 31 of the force application member 3 contacting the force receiving portion 21 (or friction at other contact points between the regulating member 2 and the force application member 3). To switch from a contact state to a separated state, for example, the force application member 3 is positioned at a position where the 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, until the regulating member 2 is positioned to contact the secondary transfer bearing 4.

<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.

As shown in Figure 14(c), it is conceivable that the secondary transfer bearing 4 will be subjected to a shipping impact in the -Z direction while the protrusion 42 of the secondary transfer bearing 4 is engaged with the groove 22 of the regulating member 2. In this case, as mentioned 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.

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. As shown in FIG. 14(b), in this embodiment, unlike the configuration of the comparative example, the force applying member 3 is configured such that the regulating biasing portion 36 contacts the bias receiving portion 63c of the drive roller 172 and the first rotation stop end 35a precedes the abutment portion 63a of the drive roller 172 in the C direction. This creates an idling region E, which is a gap 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 35a of the force applying member 3. Therefore, in response to a force in the -Z direction from the secondary transfer bearing 4, the force applying member 3 has a degree of freedom of rotation (movement) in the -C direction equivalent to the idling region E. As with the configuration of the comparative example, the drive roller 172 is connected to a drive source (not shown) and therefore does not have the freedom to rotate in the -C direction (and C direction).

Therefore, even if a logistics impact in the -Z direction rotates the force application member 3 in the -C 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 contact between the force application portion 31 and the force receiving portion 21 of the regulating member 2 (or friction at other contact points between the force application member 3 and the regulating member 2). Furthermore, 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 logistics impact. Therefore, even if a logistics impact is received, the first rotation stop end 35a of the force application member 3 abuts against the abutment portion 63a of the drive roller 172, preventing translational movement of the regulating member 2 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 separation 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 the contact 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 the contact state due to impact during transportation.

As mentioned above, the idling region E can be set appropriately taking into consideration factors such as the amount of rotation of the force application member 3 due to logistics impact. 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 approximately 10 degrees or more and 45 degrees or less, and more preferably approximately 15 degrees or more and 30 degrees or less.

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 shaped to dig into the regulating member 2 in a direction that stops the rotation of the drive roller 172 in the C direction. In other words, the protrusion 42 is formed so as to protrude toward the drive roller 172, tilted 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 digs into the regulating member 2 (groove 22), more easily causing the regulating member 2 to rotate in the -C direction. Therefore, as described above, by providing the idling region E in consideration of a 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.

On the other hand, it is also possible 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 at both ends of the drive roller 172 in the rotational axis direction, a single regulating member 2 and force applying member 3 can be provided with force receiving portions and force applying portions for both ends. 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 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 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 the 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 biasing force 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 biasing force 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 to rotate relative to the drive roller 172 in a direction returning to the stop position by its elastic restoring force. 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 can be achieved as when the secondary transfer bearing 4 rotates the regulating member 2 in the -C direction.

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 to have small rotational resistance between the drive roller 172 and the force application member 3. From this perspective, it is desirable to have a small diameter at the contact point between the drive roller 172 and the force application member 3 in the direction of the rotation axis of the drive roller 172. 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 opposite 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 that surrounds 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 to form 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 application member 3 can be reduced.

As such, in this embodiment, in the image forming apparatus 100, the gap adjustment mechanism 10 that adjusts the gap 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 gap 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 rotational 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. In addition, the position regulating unit 36 regulates the position of the force-applying member 3 in the specified 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 specified rotational direction when the force-applying member 3 rotates in the specified rotational direction in conjunction with the rotation of the rotating body 172 in the specified 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 specified 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 (abutment 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 restricts the position of the force application member 3 in the predetermined rotation direction when the rotating body 172 stops rotating, and is configured 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. Furthermore, in this embodiment, the rotating body 172 has a roller portion 172a and a rotating shaft 1 that protrudes from the end of the roller portion 172a in the direction of the rotation axis, and the force application 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.

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 is 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 is 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 so as to cause 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 on the restricting member 2 and extending in the rotation axis direction, and a protrusion 42 provided on 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. 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, forming 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.

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

[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.

In this embodiment, the configuration of the force application member 3 in the gap adjustment mechanism 10 differs from that in Example 1.

Figure 17 is a diagram illustrating 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). Figure 17(a) is a side view of the vicinity of the drive side ends of the drive roller 172 and secondary transfer roller 109 as viewed in the -Z direction. Figure 17(b) is a cross-sectional view taken along line A-A in Figure 17(a) (showing a cross section perpendicular to the rotational axis direction of the drive roller 172).

As shown in FIG. 17(b), in this embodiment, the gap adjustment mechanism 10 includes an elastically deformable restricting and biasing member 7 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 this 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 rotational direction of the drive roller 172 when the drive roller 172 stops rotating. The restricting and biasing member 7 is composed 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 abutment 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 rotational direction of the drive roller 172. The rear end 71 of the restricting and biasing member 7 in the C direction contacts the pressing portion 63e of the drive roller 172, and the front end 72 of the restricting and biasing member 7 in the C direction contacts the first rotation stopper end 35a of the force applying member 3. The force applying member 3 is configured so that the first rotation stopper end 35a of the force applying member 3 leads the pressing portion 63e of the drive roller 172 in the C direction due to the restricting and biasing member 7.

Even with this configuration, it is possible to provide an idling region E similar to that in Example 1, preventing disengagement between the regulating member 2 and the secondary transfer bearing 4 even when subjected to a physical distribution shock. Furthermore, by using a regulating and biasing member 7 that is separate 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 rotational position of the force-applying member 3, depending on the hardness of the sponge or rubber that makes it up.

When the secondary transfer roller 109, intermediate transfer belt 171, and drive roller 172 are shifted 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, causing the force applying member 3 to rotate. In other words, in this embodiment, the first rotation stop end 35a receives a force from the pressing portion 63e via the regulating and biasing member 7 that rotates the force applying member 3. This causes the regulating member 2 to translate in the direction of the rotation axis of the drive roller 172, similar to embodiment 1.

In this manner, in this embodiment, the force application 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 application member 3 in a predetermined rotational direction of the rotating body 172, the rotating body 172 has a rotational force application portion (pressing portion) 63e that applies a force that rotates the force application member 3 in the predetermined rotational direction to the rotational force receiving portion 35a, and the position restriction portion (restriction biasing member) 7 is composed of an elastic member that is arranged so as to be sandwiched between the rotational force application portion 63e and the rotational force receiving portion 35a in the predetermined rotational direction. 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 63e in the predetermined rotation direction, and the position restriction portion 7 transmits the force that rotates the force application member 3 in the predetermined rotation direction from the rotational force application portion 63e to the rotational force receiving portion 35a in a state where it is compressed and elastically deformed between the rotational force application portion 63e and the rotational force receiving portion 35a as the rotating body 172 rotates in the predetermined rotation direction.

In order to provide an idling region F similar to that described in Example 1, a second restrictive biasing 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 biasing portion 37 provided in the force application member 3 in Example 1. This second restrictive biasing member may have a configuration similar to the biasing member 7 described above. The second restrictive biasing member is disposed between the second pressing portion 63f, which corresponds to the second abutting portion 63b of the drive roller 172 in Example 1, and the second rotation stopper end portion 35b of the force application member 3, in the rotation direction of the drive roller 172.

[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.

In this embodiment, the configuration of the regulating member 2 and the force applying member 3 in the gap adjustment mechanism 10 differs from that in Example 1.

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

18 and 19(b), in this embodiment, a restricting biasing portion 26 corresponding to the restricting biasing portion 36 provided on the force application member 3 in Example 1 is provided on the restricting member 2. Also, in this embodiment, a biasing receiving portion 39a corresponding to the biasing 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 biasing portion 26 provided on the restricting member 2 has a flexible plate-shaped base 26b and a restricting action portion 26a provided on the end of the base 26b facing the force application member 3. The base 26b is configured to be deformable in a direction along the rotational direction of the drive roller 172. Also, the restricting action portion 26a is able to abut against the biasing 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.

In this embodiment, as shown in FIG. 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 direction C (idling area G) relative to the force receiving portion 21 of the regulation member 2 when the regulation biasing portion 26 comes into contact with the bias receiving portion 39a. In other words, in this embodiment, before the image forming apparatus 100 is shipped, the force application member 3 is stopped with the force receiving portion 21 of the regulation member 2 ahead of the force application portion 31 of the force application member 3 in direction C.

In this embodiment, as shown in FIG. 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.

As a result, when the secondary transfer bearing 4 receives a logistics shock in the -Z direction, the regulating member 2 is able to rotate in the -C direction within the range of the above-mentioned rotational freedom (idling region G) due to the deformation of 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 translate in the Y direction relative to the force application member 3. Therefore, even if the secondary transfer bearing 4 receives a logistics shock 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.

Even with this configuration, an idling area G is provided that acts in the same way as the idling area E in Example 1, preventing the regulating member 2 from disengaging from the secondary transfer bearing 4 even when subjected to a shipping shock. This makes it possible to stably maintain the separation between the secondary transfer roller 109 and the intermediate transfer belt 171 and drive roller 172.

In this embodiment, the force application 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 application member 3 in a predetermined rotational direction of the rotating body 172, and a biasing receiving portion 39a that abuts against the position restricting portion (restrictive biasing portion) 26. The rotating body 172 has a rotational force application portion (abutting portion) 63a that applies a force to the rotational force receiving portion 35a that rotates the force application member 3 in the predetermined rotational direction. The position restricting portion 26 is provided on the restricting member 2, and the biasing receiving portion By abutting against 39a, the relative position of the force application member 3 with respect to the regulating member 2 in the predetermined rotational direction when the rotating body 172 stops rotating is restricted to a position where the force receiving portion 21 precedes the force application portion 31 in the predetermined rotational direction, and the position restriction portion 2 abuts against the bias receiving portion 39a between the time when the rotating body 172 starts rotating in the predetermined rotational direction and the time when the force application portion 31 abuts against the force receiving portion 21, and is elastically deformed in conjunction with the rotation of the rotating body 172 in the predetermined rotational direction. Furthermore, in this embodiment, the rotational force receiving portion 35a abuts against the rotational force application portion 63a when the rotating body 172 stops rotating.

As shown in Figures 18 and 19(b), a second restrictive biasing portion 27 corresponding to the second restrictive biasing portion 37 provided on the force application member 3 in Example 1 may be provided on the regulation member 2. In this case, a second biasing receiving portion 39b corresponding to the second biasing receiving portion 63d provided on the drive roller 172 in Example 1 is provided on the force application member 3. This makes it possible to obtain the same effect as that provided by the second restrictive biasing portion 37 in Example 1.

[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.

In the above-described embodiment, the gap adjustment mechanism adjusts the gap between the rotating shaft of the drive roller that tensions the intermediate transfer belt and the secondary transfer bearing as an opposing member. However, the present invention is not limited to this configuration. The gap adjustment mechanism may also adjust the gap between other rotating shafts and opposing members. For example, the gap adjustment mechanism may adjust the gap between the rotating 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 rotating 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 rotating shaft of an image carrier (such as a photosensitive drum) and a support member that supports a charging member (such as a charging roller). Additionally, for example, the gap adjustment mechanism may adjust the gap between the rotation shaft of the image carrier (such as a photosensitive drum) and a support member that supports the developing member (such as a developing roller).

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

In the above-described embodiment, the rotational force applying portion and the biasing force receiving portion were each formed on the side surfaces of the roller rib portion of the three-pointed arrow tube that constitutes the core metal of the roller, but this is not limited to this and may also be, for example, a protrusion provided on the end surface of the roller portion of the roller.

In the above-described embodiment, the groove of the regulating member and the protrusion of the opposing member are described as being disengaged when the image forming device is shipped. However, the groove of the regulating member and the protrusion of the opposing member may be engaged when the image forming device is shipped. Even in this case, the present invention can prevent the gap between the rotating shaft and the opposing member from changing due to shocks during shipping, etc.

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 that is attached to the rotation shaft of the second rotating body, separate from the support member that rotatably supports the second rotating body (such as the secondary transfer roller) that faces the rotating body.

In the above-described embodiment, the regulating member is attached to the rotating shaft by being attached to the outer circumferential surface of the force-applying member, but this is not limited to this; the regulating member may also be attached directly to the outer circumferential surface of the rotating shaft.

1 Rotating shaft 2 Regulating member 3 Force applying member 4 Secondary transfer bearing (opposing member)
5 Secondary transfer spring (urging member)
6 Core metal 21 Force receiving portion 31 Force applying portion 35 Rotation stopping portion 35a First rotation stopping end portion (rotational force receiving portion)
36 Restriction biasing portion (position restriction portion)
63a: abutment portion (rotational force imparting portion)
63c: Force receiving portion 100: Image forming apparatus 109: Secondary transfer roller 171: Intermediate transfer belt 172: Drive roller

Claims (20)

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. 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. 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. 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. The gap adjustment mechanism described in claim 4, characterized in that the rotational force receiving portion abuts against the rotational force applying portion when the rotation of the rotating body is stopped. 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. 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 comes into contact with 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. 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. the first position is a position where the regulating member is sandwiched between the rotation shaft and the opposing member,
2. The distance 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. 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. 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. The gap adjustment mechanism described in claim 1 further comprises a guide portion that restricts movement of the restricting member so as to cause relative movement between the restricting member and the force application member, and guides the restricting member from the first position to the second position. 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. 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. The gap adjustment mechanism described in claim 1, characterized in that the first position is closer to the center of the rotating body in the direction of the rotation axis than the second position. The gap adjustment mechanism described in claim 1, characterized in that the regulating member and the force applying member are respectively provided on both end sides of the rotating body in the direction of the rotation axis. The gap adjustment mechanism described in claim 1, characterized in that the opposing member is a support member that rotatably supports the second rotating body and is movable toward and away from the rotation axis. 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. The gap adjustment mechanism described in claim 18, characterized in that the second rotating body is spaced apart from the belt when the regulating member is in the first position. 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: