JP2024011832A - Belt device, transfer device, and image forming apparatus - Google Patents

Abstract

To reduce a force applied to a transmission unit that transmits a driving force to a holding member.SOLUTION: A transfer device 20 comprises: an intermediate transfer belt 2 that travels in circle; a holding member 101 that holds down the intermediate transfer belt 2; and a transmission unit that transmits a driving force to the holding member 101. The holding member 101 is provided to be able to reciprocate between a holding attitude where it holds down the intermediate transfer belt 2 and a retreat attitude where it retreats from the intermediate transfer belt 2. The transmission unit transmits the driving force to the holding member 101, and thereby the holding member 101 is changed to the retreat attitude. The holding member 101 is changed by its own weight to a side of the holding attitude.SELECTED DRAWING: Figure 6

Description

The present invention relates to a belt device, a transfer device, and an image forming apparatus equipped with the transfer device.

BACKGROUND ART Belt members such as intermediate transfer belts may warp toward the outer circumference due to an increase in temperature at the ends in the width direction of the belt, indoor humidity, or the like.

On the other hand, by providing a pressing member that presses the belt member from the outer peripheral surface side, warping of the belt can be improved.

For example, the image forming apparatus disclosed in Patent Document 1 (Japanese Patent No. 6,394,151) is provided with a pressing member that presses an end of a belt member. The holding member is attached to a rotating holding member. A contact/separation mechanism that brings each primary transfer roller toward and away from the photoreceptor rotates the holding member, so that the pressing member can be brought into contact with and away from the belt member.

However, in the image forming apparatus of Patent Document 1, a mechanism for bringing each primary transfer roller into contact with and away from the photoreceptor and a mechanism for bringing a belt presser into contact with and away from a belt member are linked together. Therefore, in order to operate the belt presser, all the primary transfer rollers must be moved away from the photoreceptor, and a large force is required to move the belt presser toward and away from the photoreceptor. For this reason, each member of the transmission section that transmits the driving force to the belt holder is likely to be damaged, and these members need to have a certain amount of strength to prevent damage. For this reason, there are problems in that the design of each member of the transmission section is restricted and the cost increases.

An object of the present invention is to reduce the force applied to a transmission section that transmits driving force to a holding member.

In order to solve the above problems, the present invention provides a belt device including a belt member that runs around the belt member, a pressing member that presses the belt member, and a transmission section that transmits a driving force to the pressing member, The pressing member is provided so as to be able to reciprocate between a pressing position in which it presses the belt member and a retracted position in which it retracts from the belt member, and when the transmission section transmits a driving force to the pressing member, the pressing member The holding position is changed to the retracted position, and the holding member changes its position to the holding position due to its own weight.

According to the present invention, it is possible to reduce the force applied to the transmission section that transmits the driving force to the pressing member.

1 is a schematic configuration diagram of an image forming apparatus. FIG. 3 is a perspective view of the transfer device. FIG. 3 is a perspective view showing the configuration of a transmission section that transmits a driving force to a holding member, and is a diagram showing a state of a retracted posture. It is a perspective view which shows the structure of the transmission part which transmits a driving force to a holding|suppressing member, and is a figure which shows the state of the holding|suppressing posture. FIG. 3 is a perspective view showing the configuration around the holding member. It is a figure which shows the structure of a holding member's periphery, and is a figure which shows the state of a retracted attitude|position. It is a figure which shows the structure of the holding member periphery, and is a figure which shows the state of a holding|pressing posture. FIG. 7 is a front view in a retracted state with the release lever removed. FIG. 7 is a front view in a pressed state with the release lever removed. FIG. 3 is a perspective view showing the lever fixing shaft and first to fourth link members. FIG. 3 is an exploded perspective view of the first to fourth link members. FIG. 7 is a front view of the first to fifth link members in a retracted state, showing operations of the first to fifth link members. FIG. 7 is a front view showing the operation of the first to fifth link members, in the middle of transition from the retracted state to the pressed state. FIG. 7 is a front view of the first to fifth link members in a pressed state, showing the operations thereof. FIG. 3 is a rear view showing the configuration around the downstreammost primary transfer section in a retracted state. FIG. 7 is a rear view showing the configuration around the downstreammost primary transfer section in a pressed state. FIG. 3 is a perspective view showing the second axis and its peripheral configuration. FIG. 18 is a perspective view of the shaft portions forming the second shaft separated from FIG. 17; It is a figure which shows the separated state of the center side shaft part and the end side shaft part of one side. It is a figure which shows the separated state of the center side shaft part and the other end side shaft part. It is a figure which shows a 1st cam and a cam follower. FIG. 2 is a schematic configuration diagram of the transfer device, in which (a) the primary transfer parts are in contact with each other, and (b) the primary transfer parts are all separated from each other. It is a perspective view showing a cam member. FIG. 3 is a perspective view of the cam member and its surrounding structure as viewed from the back side. FIG. 3 is a diagram showing a configuration in which the most downstream primary transfer section approaches and separates from the intermediate transfer belt, as seen from the back side of the image forming apparatus, and shows a "separated" state. FIG. 3 is a plan view showing the configuration around the first arm and the second arm. FIG. 2 is a perspective view showing the configuration of a second arm and its surroundings. FIG. 3 is a perspective view of the configuration of the second arm and its surroundings, viewed from the back side. FIG. 3 is a plan view showing the arrangement of a detection sensor and a sensor bracket when they come into contact with each other. FIG. 7 is a plan view showing how the second sensor bracket is positioned in a “separated” state. It is a figure which shows the structure of the release lever vicinity, and is a front view of the state where the lever part is arrange|positioned in the retracted position. It is a figure which shows the structure around a release lever, and is a front view of the state where the lever part is arrange|positioned in the holding position. FIG. 3 is a plan view showing a structure in which the central primary transfer unit and the most upstream primary transfer section approach and separate from the intermediate transfer belt.

Embodiments according to the present invention will be described below with reference to the drawings. In each figure, the same or corresponding parts are denoted by the same reference numerals, and repeated explanations thereof will be simplified or omitted as appropriate.

FIG. 1 is a diagram showing the configuration of an image forming apparatus 1 according to an embodiment of the present invention. An image forming apparatus 1 shown in FIG. 1 is a color printer having a tandem configuration in which a plurality of photoreceptors serving as latent image carriers are arranged side by side. Each photoreceptor can form a toner image of a color corresponding to color separation using toner as a developer supplied from a developing device. After the toner images formed on each photoconductor are superimposed and transferred to a transfer belt, the superimposed images are transferred all at once to a sheet such as recording paper, thereby forming a multicolor image on the sheet. In the present invention, the image forming apparatus is not limited to a color printer, but also includes a color copying machine, a facsimile machine, a printing machine, and the like.

In FIG. 1, the image forming apparatus 1 includes an image forming section 1A disposed near the center in the vertical direction, a paper feed section 1B below the image forming section 1A, and an original document mounting table 1C1 above the image forming section 1A. Scanning units 1C are arranged respectively. An intermediate transfer belt 2 is arranged in the image forming section 1A. The intermediate transfer belt 2 has a horizontally extending surface. A configuration is provided above the intermediate transfer belt 2 for forming an image of colors complementary to the color separation colors.

One embodiment of the belt member of the present invention is a transfer belt for transferring an image. The intermediate transfer belt 2 of this embodiment is an example of this transfer belt. However, the example of the belt member of the present invention is not limited to the intermediate transfer belt 2 as an intermediate transfer body. For example, the belt member of the present invention may be a conveyor belt that conveys a recording medium and forms a transfer nip with the photoreceptor.

The image forming section 1A is provided with a plurality of PCDUs (Photo Conductor Development Units) that are latent image carrier units. Each of the PCDUs 10K, 10C, 10M, 10Y, and 10T can form an image using complementary color toners (yellow, magenta, cyan, and black) and a glossy image using transparent toner. Each of the PCDUs 10K, 10C, 10M, 10Y, and 10T has a photoreceptor 3K, 3C, 3M, 3Y, and 3T (transparent toner) as a latent image carrier capable of carrying an image along the stretched surface of the intermediate transfer belt 2. juxtaposed. In the following description, if the content is common to all photoconductors, the photoconductor is indicated by the reference numeral 3. Moreover, PCDU10K, 10C, 10M, 10Y, and 10T are also called PCDU10. The PCDU 10 includes at least a photoreceptor 3, and in this embodiment, a developing device and the like.

Each of the photoreceptors 3K, 3C, 3M, 3Y, and 3T is composed of a drum that can rotate in the same direction (counterclockwise in FIG. 1). A charging device, a writing device 5, a developing device 6, a primary transfer roller 7 as a primary transfer member, and a cleaning device are arranged. (shown).

The transfer device 20 as a belt device includes an intermediate transfer belt 2, a plurality of primary transfer rollers 7 as transfer members (for convenience, only the primary transfer roller 7T is shown with a reference numeral), and a plurality of rollers 2A to 2C. Equipped with.

Toner images from the PCDU 10 including each photoreceptor 3 are sequentially transferred to the intermediate transfer belt 2 . The intermediate transfer belt 2 is wound around a plurality of rollers 2A to 2C and a plurality of rollers not numbered in FIG. 1, and can travel in the direction of the arrow in FIG. The rollers 2A and 2B stretch the intermediate transfer belt 2 on both sides of the outer side in the running direction of the intermediate transfer belt 2 at opposing positions facing each photoreceptor 3 of the intermediate transfer belt 2. The secondary transfer opposing roller 2C faces the secondary transfer device 9 with the intermediate transfer belt 2 in between.

The secondary transfer device 9 has a secondary transfer roller 9A. The secondary transfer roller 9A forms a secondary transfer nip with the secondary transfer opposing roller 2C with the intermediate transfer belt 2 in between. A secondary transfer bias having the same polarity as the toner is applied to the secondary transfer opposing roller 2C, while the secondary transfer roller 9A is grounded. As a result, a secondary transfer electric field is formed in the secondary transfer nip that electrostatically moves the multicolor toner image on the intermediate transfer belt 2 from the belt side toward the secondary transfer roller 9A side. This secondary transfer nip transfers a multicolor toner image onto the sheet conveyed to the secondary transfer nip.

Paper as a recording medium is fed to the secondary transfer position from the paper feed section 1B. The paper feed section 1B includes a plurality of paper feed cassettes 1B1 and a plurality of transport rollers 1B2. The plurality of conveyance rollers 1B2 are arranged on a conveyance path for sheets fed out from the paper feed cassette 1B1.

The writing device 5 irradiates the photoreceptors 3K, 3C, 3M, 3Y, and 3T with writing light to form electrostatic latent images on the photoreceptors 3K, 3C, 3M, 3Y, and 3T according to image information. This image information is obtained by scanning the original on the original mounting table 1C1 included in the original scanning unit 1C, or from image information output from a computer.

The document scanning section 1C is equipped with a scanner 1C2 and an automatic document feeder 1C3. The scanner 1C2 exposes and scans the original on the original placing table 1C1. The automatic document feeder 1C3 is arranged on the upper surface of the document placement table 1C1. The automatic document feeder 1C3 has a configuration capable of reversing the document fed onto the document placement table 1C1, and is capable of scanning both the front and back sides of the document.

The electrostatic latent image formed on the photoreceptor 3 by the writing device 5 is processed into a visible image by a developing device 6 (indicated by reference numeral 6T for convenience in FIG. 1), and is primarily transferred to the intermediate transfer belt 2. Ru. When the toner images of each color are superimposed and transferred onto the intermediate transfer belt 2, the toner images of the respective colors are secondarily transferred all at once onto a sheet of paper by the secondary transfer device 9.

The unfixed image carried on the surface of the paper subjected to the secondary transfer is fixed by the fixing device 11 . The fixing device 11 includes a belt fixing structure including a fixing belt heated by a heating roller and a pressure roller opposing and abutting the fixing belt. By providing a contact area, that is, a nip area, between the fixing belt and the pressure roller, the heating area for the paper can be expanded compared to the structure of the heat roller fixing system.

The conveyance direction of the paper that has passed through the fixing device 11 is switched by a conveyance path switching claw arranged at the rear of the fixing device 11. Specifically, the conveyance direction is selected by the conveyance path switching claw between the conveyance path toward the paper discharge section 13 and the reverse conveyance path RP.

In the image forming apparatus 1 having the above configuration, the uniformly charged photoreceptor 3 is exposed to light by scanning the original placed on the original placing table 1C1 or by using image information from a computer. After the electrostatic latent image is processed into a visible image by the developing device 6, the toner image is primarily transferred onto the intermediate transfer belt 2. The above PCDU 10, writing device 5, transfer device 20, secondary transfer device 9, fixing device 11, etc. constitute an image forming section that forms an image.

In the case of a single color image, the toner image transferred to the intermediate transfer belt 2 is directly transferred onto the paper fed out from the paper feed section 1B, and in the case of a multicolor image, the primary transfer is repeated and the toner image is superimposed. and then secondary transfer is performed on the paper all at once. After the unfixed image is fixed on the paper after the secondary transfer by the fixing device 11, the paper is fed to the paper discharge section 13 or reversed and fed again to the secondary transfer position.

In FIG. 1, the intermediate transfer belt 2 is composed of a single layer or multiple layers of PVDF (vinyldene fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), etc. Constructed by dispersing conductive material such as carbon black. The volume resistivity of the intermediate transfer belt 2 is adjusted to be in the range of 10 ⁸ to 10 ¹² Ωcm, and the surface resistivity is adjusted to be in the range of 10 ⁹ to 10 ¹³ Ωcm. Note that a release layer may be coated on the surface of the intermediate transfer belt 2 if necessary. Materials used for the coating include ETFE (ethylene-tetrafluoroethylene copolymer), PTFE (polytetrafluoroethylene), PVDF (vinyldene fluoride), PEA (perfluoroalkoxy fluororesin), and FEP (tetrafluoroethylene). Fluororesins such as ethylene fluoride-propylene hexafluoride copolymer) and PVF (vinyl fluoride) can be used, but are not limited thereto. The intermediate transfer belt 2 can be manufactured by a casting method, a centrifugal molding method, etc., and its surface may be polished if necessary. If the volume resistivity of the intermediate transfer belt 2 exceeds the above-mentioned range, the bias required for transfer will increase, which is undesirable because it will lead to an increase in power supply cost. Further, the charging potential of the intermediate transfer belt 2 becomes high during the transfer process, the transfer paper peeling process, etc., and self-discharge becomes difficult, so it becomes necessary to provide a neutralizing means. In addition, if the volume resistivity and surface resistivity are below the above range, the charge potential decays quickly, which is advantageous for eliminating static electricity by self-discharge, but since the current flows in the surface direction during transfer, toner scattering may occur. It ends up. Therefore, the volume resistivity and surface resistivity of the intermediate transfer belt 2 in this embodiment are preferably within the above ranges. The volume resistivity and surface resistivity were measured by connecting an HRS probe (inner electrode diameter 5.9 mm, ring electrode inner diameter 11 mm) to a high resistance resistivity meter (manufactured by Mitsubishi Chemical Corporation: Hiresta IP), and measuring the intermediate transfer belt 2. A voltage of 100 V (surface resistivity is 500 V) was applied to the front and back surfaces of the substrate, and the measured value 10 seconds later was used.

The intermediate transfer belt 2 is wound around at least a pair of rollers 2A and 2B, and a secondary transfer opposing roller 2C provided at a secondary transfer position, so that the drive roller 2A is set to rotate clockwise. The intermediate transfer belt 2 can be moved in the direction of the arrow shown inside the intermediate transfer belt 2 in FIG. The transfer surface of the belt moving between rollers 2A and 2B faces photoreceptors 3K, 3Y, 3C, 3M, and 3T of each image forming unit. At a position facing each photoconductor with the intermediate transfer belt 2 in between, there is a primary transfer roller 7 (in FIG. 1, a primary transfer roller 7 is used for special toner), which corresponds to a transfer member for electrostatically transferring the visible image on the photoconductor. 7T) are arranged respectively.

The primary transfer roller 7 used in this embodiment is one in which a foamed resin agent is applied to a metal core (iron, SUS, AI, etc.). The wall thickness of the foamed resin agent is 2 mm to 10 mm. Note that a known blade-like or brush-like member can also be used as the transfer member.

In this embodiment, in addition to the toner used for full-color image formation, white toner is used for the purpose of forming a white base on the image. In addition, a transparent toner may be used to improve the glossiness and transferability of the image, and a light cyan toner, light magenta toner, etc. may be selected to increase the color gamut. In order to create a colored metallic color such as red copper or bronze, metallic toner such as gold toner or silver toner may be used as a base.

By the way, in a rotating belt member such as the intermediate transfer belt 2, the widthwise ends of the belt may move toward the outer circumferential side due to temperature rise and humidity at the ends of the belt in the width direction, elongation of the stretched belt, etc. It will warp. On the other hand, in the present embodiment, a pressing member is provided that presses the widthwise end side of the intermediate transfer belt 2 from the outer circumferential side. Hereinafter, this holding member and a mechanism for changing the posture of the holding member will be explained.

As shown in FIG. 2, the inner cover 20A, which is a part of the transfer frame, is provided with a release lever 71 as an operating member. The release lever 71 has a lever portion 71a as an operating portion. Further, the transfer device 20 includes a plurality of pressing members 101. The pressing member 101 can press the outer circumferential surface of the intermediate transfer belt 2 on the widthwise end side thereof. In this embodiment, presser members 101A to 101D are arranged at two locations on both sides of the intermediate transfer belt 2 in its running direction.

The configuration having such a pressing member 101 is particularly suitable for application to a belt member having an elastic layer and having a plurality of layers made of different materials. Since each layer of such a belt member has a different coefficient of expansion with respect to temperature and humidity, the end portions in the width direction of the belt member tend to warp, and by providing the above-mentioned pressing member, the warp of the belt member can be effectively corrected. The intermediate transfer belt 2 of this embodiment has a plurality of layers including an elastic layer on the photoreceptor side and a base layer on the primary transfer roller side.

The pressing member 101 can reciprocate between a pressing position in which it comes into contact with the surface of the intermediate transfer belt 2 and presses the end of the belt, and a retracted position in which it is retracted from the intermediate transfer belt 2 . For example, during image formation, the holding member 101 takes a retracted position, and during maintenance, the holding member 101 takes a holding position to correct warping of the end portion of the intermediate transfer belt 2.

The attitude of the intermediate transfer belt 2 can be changed by the operator rotating the lever portion 71a. Specifically, when the lever portion 71a is in the position shown in FIG. 3, the pressing member 101 is in the retracted position, and when the lever portion 71a is rotated in the position shown in FIG. 4, the pressing member 101 is in the pressing position. Hereinafter, the position of the lever portion 71a in FIG. 3 will also be referred to as the retracted position where the pressing member 101 is in the retracted position, and the position of the lever portion 71a in FIG. 4 will also be referred to as the pressing position where the pressing member 101 is in the pressing position. Further, a state in which the pressing member 101 is placed in the retracted position is also referred to as a retracted state, and a state in which the holding member 101 is placed in the pressed position is also referred to as a pressed state.

The operating force of the lever portion 71a is transmitted to the fourth link member 76 shown in FIG. 3 via the first link member, the second link member, and the third link member.

One end of the fourth link member 76 is connected to the other end of the fifth link member 77. One end of the second shaft 102 is inserted into the fifth link member 77, and the fifth link member 77 rotates around the second shaft 102. The operating force of the lever portion 71a is transmitted to the fifth link member 77 via the fourth link member 76, and the fifth link member 77 rotates around the second shaft 102. That is, the second shaft 102 is rotated by the operating force of the lever portion 71a. First cams 82 are provided on both sides of the second shaft 102 in the axial direction.

As shown in FIG. 5, the first cam 82 provided on the second shaft 102 contacts the cam follower 83. The slide mechanism 105 is interlocked with the cam follower 83. The slide mechanism 105 has a pin 105a inserted into the hole 101d of the holding member 101.

The holding member 101 has a holding part 101a and a holding part 101b. The holding part 101b holds the pressing part 101a. The holding portion 101b is molded from a resin material. The holding portion 101a includes a support portion 101a1 and a felt member 101a2 as an abutting portion. The support portion 101a1 supports the felt member 101a2. The felt member 101a2 is a portion that comes into contact with the surface of the intermediate transfer belt 2. By bringing the felt member 101a2 into contact with the intermediate transfer belt 2, damage to the surface of the intermediate transfer belt 2 can be prevented. Furthermore, since the support portion 101a1 is not a portion that slides on the intermediate transfer belt 2, it is molded from a resin material with emphasis on strength.

Next, how the posture of the holding member 101 changes due to the rotation of the first cam 82 will be explained using FIGS. 6 and 7. 6 is a diagram showing the holding member 101 in the retracted position, and FIG. 7 is a diagram showing the holding member 101 in the holding position.

As shown in FIG. 6, the holding member 101 rotates around a fulcrum portion 101e provided on the holding portion 101b. Due to this rotation, the holding member 101 reciprocates between the retracted position and the holding position. In the retracted position of FIG. 6, the pin 105a of the slide mechanism 105 is arranged on the right end side of the hole 101d of the holding member 101 in FIG. This restricts the counterclockwise rotation of the holding member 101 about the fulcrum portion 101e, and the holding member 101 is placed in the retracted position.

As the first cam 82 rotates from FIG. 6 to FIG. 7, it presses the cam follower 83 to the left in FIG. 6, and the cam follower 83 and the slide mechanism 105 interlocked therewith move to the left in FIG. As a result, the pin 105a moves to the left in FIG. 6 within the hole 101d. As a result, the force of the pin 105a that restricts the counterclockwise rotation of the holding member 101 is released, and the holding member 101 rotates in the counterclockwise direction in FIG. 6 due to its own weight. As a result, as shown in FIG. 7, the holding member 101 changes from the retracted position to the holding position and comes into contact with the intermediate transfer belt 2.

Conversely, as the first cam 82 rotates from FIG. 7 to FIG. 6, the slide mechanism 105 is pushed by the first cam 82 and moves to the right in FIG. As a result, the pin 105a presses the presser member 101 (transmits driving force to the presser member 101), and rotates the presser member 101 clockwise. As a result, the holding member 101 returns to the retracted position. The holding member 101 maintains the retracted position due to its own weight and regulation by the pin 105a.

Next, FIG. 8 shows the first to third link members that are provided between the lever portion 71a and the fourth link member 76 shown in FIG. 3 and transmit the operating force of the lever portion 71a to the fourth link member 76 side. , will be explained using FIG. 8 and 9 are diagrams with the inner cover and operating lever removed, FIG. 8 is a diagram with the pressing member 101 in the retracted position, and FIG. 9 is a diagram with the pressing member 101 in the pressing position.

A lever fixing shaft 71b, which is a rotating shaft of the lever portion 71a shown in FIG. 3, is shown in FIG. The first link member 73 is attached to the transfer frame via a lever fixing shaft 71b. The lever fixing shaft 71b is a rotating shaft that rotates by the operator's operating force on the lever portion 71a. The first link member 73 rotates around the lever fixed shaft 71b. The lever fixing shaft 71b is one aspect of the first shaft of the present invention.

The first link member 73 is connected to a second link member and a third link member, which will be described later, at a connecting portion 73a. Further, in the first link member 73, one end of a spring 78 is attached to a mounting portion 73b. The other end of the spring 78 is fixed to the transfer frame.

Due to the tensile force of the spring 78, the first link member 73 receives a force that causes it to rotate clockwise in FIG. 8 about the lever fixing shaft 71b. This tensile force places the lever portion 71a in the retracted position shown in FIG. 3. On the other hand, when the operator rotates the lever portion 71a of the release lever 71 from FIG. 3 to FIG. 4, the first link member 73 rotates counterclockwise against the tensile force of the spring 78, and as shown in FIG. placed in position. In this way, the spring 78 is a biasing member that biases the first link member 73 in the direction of the rotational phase in the retracted position.

The rotational force of the first link member 73 is transmitted to the fifth link member 77 via a second link member, a third link member, and a fourth link member 76, which will be described later. As a result, as shown in FIG. 8→FIG. 9, the fourth link member 76 moves to the left in FIG. 9, and the fifth link member 77 rotates clockwise in FIG. 9 about the second shaft 102. As a result, the holding member 101 changes its posture as described above. Furthermore, regulating members 72C and 72 are attached to the fourth link member 76, and change their postures in conjunction with the fourth link member 76.

Next, the second link member, the third link member, and the first link member 73 and fourth link member 76 connected thereto will be explained using FIGS. 10 and 11. 10 is a perspective view of FIG. 9 with the regulating member 72T removed, and FIG. 11 is an exploded perspective view of each link member.

As shown in FIGS. 10 and 11, the connecting portion 73a of the first link member 73 is inserted into holes provided in one end 74a of the second link member 74 and one end 75a of the third link member 75, respectively. Thereby, the first link member 73, the second link member 74, and the third link member 75 are connected. An E-ring is interposed between one end 74a of the second link member 74 and one end 75a of the third link member 75 to reduce the contact area between the one end 74a and the one end 75a.

The insertion portion 74b, which is the other end of the second link member 74, is inserted into the hole 76a of the fourth link member 76, and the second link member 74 is connected to the fourth link member 76. Further, the insertion portion 75b, which is the other end of the third link member 75, is inserted into the elongated hole 76b of the fourth link member 76, and the insertion portion 75b is provided so as to be relatively movable within the elongated hole 76b. The first link member 73 has an insertion hole 73c into which the lever fixing shaft 71b is inserted. As shown in FIG. 10, between the first link member 73 and the lever fixed shaft 71b, between the connecting portion 73a and the third link member 75, between the insertion portion 75b and the fourth link member 76, and the insertion portion 74b. E-rings are also interposed between and the fourth link member 76, respectively.

Next, as the first link member 73 rotates about the lever fixed shaft 71b, rotational force is transmitted to the fourth link member 76 via the second link member 74 and the third link member 75, and the rotational force is transmitted to the fourth link member 76. How 76 moves in the left-right direction shown in FIG. 8 will be explained using FIGS. 12 to 14. FIG. 12 is a diagram of the retracted state, FIG. 13 is a diagram of the transition from the retracted state to the pressed state, and FIG. 14 is a diagram of the pressed state. Note that in FIGS. 13 and 14, for convenience, the E-ring interposed between the insertion portion 75b and the fourth link member 76 is not shown.

In FIGS. 12 to 14, the lever fixing shaft 71b and the second shaft 102 are fixed to the transfer frame, and their positions do not change.

As shown in FIG. 12→FIG. 13, when the first link member 73 rotates counterclockwise around the lever fixing shaft 71b, the second link member 74 and the third link member connected to the first link member 73 at the connecting portion 73a The link member 75 changes its position in conjunction with the first link member 73. As the second link member 74 and the third link member 75 move, the fourth link member 76 connected to the second link member 74 at the insertion portion 74b moves in the left-right direction in FIG. Link member 77 rotates around second axis 102 .

The position to which the fourth link member 76 moves is determined by inserting the insertion portion 75b of the third link member 75 into the long hole 76b of the fourth link member 76. That is, the lever fixed shaft 71b and the second shaft 102 are fixed to the transfer frame, and the positions of the second link member 74 and the fourth link member 76, which are arranged between these two points, are respectively variable. Therefore, simply by connecting the second link member 74 and the fourth link member 76, the position of the fourth link member 76 cannot be determined with respect to a change in position due to rotation of the first link member 73. However, since the movement range of the insertion portion 75b, which is the other end of the third link member 75, is restricted within the elongated hole 76b of the fourth link member 76, the relative relationship between the third link member 75 and the fourth link member 76 is Location is regulated. Thereby, the positions of the first link member 73 and the fourth link member 76 can be made to correspond one-to-one, and the fourth link member 76 can be moved to a predetermined position with respect to the rotation of the first link member 73. be able to. Note that in the retracted position shown in FIG. 12, the insertion portion 75b of the third link member 75 is disposed at one end of the elongated hole 76b of the fourth link member 76, and the fourth link member 76 is positioned in the left direction in FIG. It is regulated to prevent further movement. Further, in the pressed state position shown in FIG. 14, the insertion portion 75b is disposed at the other end of the elongated hole 76b, and the fourth link member 76 is restricted from moving further to the right in FIG.

The first link member 73 rotates counterclockwise as shown in FIG. 12 and moves to the pressed state position shown in FIG. do. On the other hand, since a clockwise force is applied to the first link member 73 by the spring 78, when the operating force is released at a position other than the pressed state, the first link member 73 automatically returns to the retracted state shown in FIG. do.

On the other hand, in the pressed state shown in FIG. 14, the first link member 73 is fixed at that position. Therefore, even if the operator releases the operating force on the lever part 71a in the holding state, the lever part 71a and the first link member 73 do not return to the retracted state position. The fixing mechanism for fixing the lever portion 71a and the first link member 73 in the pressed position will be described with reference to FIGS. 15 and 16. 15 and 16 are views of the transfer device from the back side of the image forming apparatus, with FIG. 15 showing the retracted state and FIG. 16 showing the pressed state.

As shown in FIG. 15, one end of a spring 79 is connected to the front slider 32, which is a mechanism for bringing the primary transfer roller 7T into and out of contact with each other. The other end of the spring 79 is fixed to the transfer frame and urges the front slider 32 to the left in FIG. A cam follower 81 is attached to the front slider 32.

A cam 80 as a fixing member is attached to the lever fixing shaft 71b, which is the rotation axis of the release lever. In the retracted state shown in FIG. 15, the cam 80 is out of contact with the cam follower 81. On the other hand, in the pressed state shown in FIG. 16, the cam 80 is rotated by operating the release lever, so that the cam 80 comes into contact with the cam follower 81. The cam follower 81 provided on the front slider 32 is biased toward the left in FIG. 16 . When the cam follower 81 comes into contact with the cam 80, the position of the cam 80, that is, the rotational phase of the lever fixing shaft 71b is fixed. As a result, the lever portion 71a of the release lever 71 is fixed in the pressed position.

As described above, by configuring the lever portion 71a to automatically return to the retracted position at positions other than the pressing position, the lever portion 71a is placed in either the pressing position or the retracted position, and is placed in a halfway position between them. You can prevent this from happening. Therefore, the holding member 101 (see FIG. 6) can be placed in either the holding position or the retracted position.

To summarize each of the above operations, first, the holding member 101 is placed in the retracted position shown in FIG. 6 by rotating the first cam 82 to a predetermined phase by the tensile force of the spring 78 shown in FIG. That is, spring 78 (see FIG. 12) → first link member 73 → second link member 74 (third link member 75) → fourth link member 76 → fifth link member 77 → second shaft 102 → first cam The tensile force of the spring 78 is transmitted in the order of 82 (see FIG. 6). The rotation of the first cam 82 causes the cam follower 83 and the slide mechanism 105 to move. The pin 105a of the slide mechanism 105 moves to the right in FIG. 7 within the hole 101d, and the holding member 101 rotates clockwise to be placed in the retracted position. The second link member 74, the third link member 75, the fourth link member 76, and the fifth link member 77 transmit driving force between the first link member 73, the first cam 82, and the second shaft 102. This is another link member for transmission.

On the other hand, when the operator rotates the lever portion 71a from FIG. 3 to FIG. 4, the first link member 73 rotates, and a force is applied in the opposite direction to the slide mechanism 105 in the same order as described above. As a result, the pin 105a of the slide mechanism 105 moves to the left in FIG. 6 within the hole 101d. As a result, the holding member 101 becomes rotatable counterclockwise, and the holding member 101 rotates counterclockwise as shown in FIGS. 6 to 7 due to its own weight, and the holding member 101 is placed in the holding position.

In this manner, the present embodiment is configured such that the holding member 101 changes its posture to the holding posture side due to its own weight. Therefore, in order to move the holding member 101 toward the holding position, it is not necessary to apply force such as the spring force of a spring. Therefore, the force acting on each member constituting the above-mentioned transmission section that transmits the driving force to the pressing member 101 can be reduced. Therefore, the force applied to each member constituting the transmission section can be reduced, and damage to these members can be suppressed. Alternatively, the strength of these members can be made relatively small by forming them from materials with low strength, thereby increasing the degree of freedom in design and reducing costs. The transmission section is a section that transmits a driving force to the pressing member 101 to change the position to the retracted position, and includes the first link member 73, the second link member 74, the third link member 75, the fourth link member 76, and the fifth link member 74. It includes a link member 77, a second shaft 102, a first cam 82, a cam follower 83, a slide mechanism 105, and the like.

Furthermore, when the lever portion 71a is placed in the pressed position shown in FIG. 4, the tensile force of the spring 79 is transmitted to the cam 80 via the cam follower 81 as shown in FIG. 16, and the rotational phase of the lever fixing shaft 71b is fixed. Ru. As a result, the slide mechanism 105 is held in the position shown in FIG. 7, and the pressing member 101 maintains the pressing posture by its own weight. That is, by simply fixing the rotational phase of the lever fixing shaft 71b, the pressing member 101 can maintain its pressing posture by its own weight. Therefore, similarly to when the holding member 101 is changed from the retracted position to the holding position, the force acting on each member constituting the transmission section can be reduced.

As described above, in this embodiment, the force acting on each member constituting the transmission section can be reduced when changing from the retracted posture to the pressing posture and when maintaining the pressing posture. For example, the first cam 82 is only subjected to a sliding load with respect to the cam follower 83 due to rotation, a force exerted by the own weight of the pressing member 101, and a reaction force due to the pressing member 101 pushing the intermediate transfer belt.

Next, the procedure for disassembling and removing the second shaft 102 will be explained using FIGS. 17 to 20. In the following description, among the first cams 82 provided on both sides of the second shaft 102 in the axial direction, the first cam 82 on one side will be referred to as a first cam 82A, and the first cam 82 on the other side will be referred to as a first cam 82B. shall be.

As shown in FIG. 17, the central shaft portion 1021 constituting the second shaft 102 is screwed to the end shaft portions on both sides in the axial direction via first cams 82A and 82B, respectively. . The second shaft 102 is configured by connecting a center shaft portion 1021 and end shaft portions 1022 (see FIG. 19) and 1023 (see FIG. 20) via first cams 82A and 82B.

When disassembling the second shaft 102 to remove it from the transfer device, first remove the screws 107 and 108. By removing the screw 107, the first cam 82A and the central shaft portion 1021 are separated. By removing the screw 108, the first cam 82B and the end-side shaft portion 1022 are separated. Then, by moving the first cam 82B in the direction of arrow C, the state shown in FIG. 18 is achieved. Thereby, the central shaft portion 1021 becomes removable. In other words, as shown in FIG. 19, by moving the first cam 82B in the direction of arrow C, the center shaft portion 1021 and one end shaft portion 1022, which were connected via the first cam 82B in FIG. are separated. Further, as shown in FIG. 20, on the other axial side, the other axial end of the central shaft portion 1021 is inserted into the cylindrical portion 821 of the first cam 82A. In the state shown in FIG. 17, the center shaft portion 1021 and the other end shaft portion 1023 are connected by the screw 107 via the first cam 82A. Therefore, by removing the screw 107, the central shaft portion 1021 and the other end shaft portion 1023 are separated. From the state shown in FIG. 18, the center side shaft portion 1021 can be removed by pushing the center side shaft portion 1021 and the first cam 82B in an oblique direction and pulling out the center side shaft portion 1021 from the cylindrical portion of the first cam 82A. can.

In this embodiment, since the force applied to the second shaft 102 and the first cams 82A, 82B is small when maintaining the holding posture, the central shaft portion 1021 and the end shaft portions 1022, 1023 are It can be easily installed using screws. Therefore, as described above, it is possible to easily disassemble the second shaft 102 and remove the central shaft portion 1021. This facilitates replacement and maintenance of parts inside the image forming apparatus that are located further back than the second shaft 102.

Further, the first cam 82 has a cylindrical portion 821 into which the second shaft 102 is inserted and a cam portion 822, as shown in FIG. That is, the first cam 82 also serves as a connecting portion for connecting the cam portion 822 that transmits the driving force and the plurality of shaft portions 1021, 1022, and 1023 that constitute the second shaft 102. This allows the number of parts to be reduced.

Next, a mechanism for limiting the rotation range of the release lever 71 to the range from the retracted position in FIG. 3 to the pressed position in FIG. 4 will be described using FIG. 21.

The rotation range of the release lever 71 is limited by the rotation range of the fifth link member 77 shown in FIG. 12 being restricted, and the movement range of the insertion portion 76c being restricted within the elongated hole 75b. The rotation range of the fifth link member 77 is restricted by restricting the rotation range of the first cam 82 coaxial with the fifth link member 77. In other words, the rotation range of the first cam 82 is limited to the range from the retracted position shown in FIG. 6 to the pressed position shown in FIG.

As shown in FIG. 21, the cam follower 83 has a first abutted surface 83a as a first abutted part that is in contact with the first cam 82, and a second abutted surface 83a as a second abutted part. It has a contact surface 83b. The first cam 82 also has a first contact portion 82a that contacts a first contact surface 83a, and a second contact portion 82b that contacts a second contact surface 83b. In FIG. 6, the first contact portion 82a contacts the second contact surface 83b to regulate the position of the cam follower 83, and in FIG. 7, the first contact portion 82a contacts the first contact surface 83a. This restricts the position of the cam follower 83.

In this way, by arranging the contact surfaces of the cam followers 83 on both sides of the first cam 82, the first cam 82 can contact the cam followers 83 and slide even when the first cam 82 rotates in any direction. Mechanism 105 can be moved. Therefore, there is no need for the first cam 82 to always slide in contact with the cam follower 83, and there is no need to provide a spring or the like.

The distance B2 between the first abutted surface 83a and the second abutted surface 83b is set smaller than the distance B1 between the first abutted part 82a and the second abutted part 82a. Thereby, the rotation range of the first cam 82 can be restricted as described above. Note that the distance B1 between the first contact portion 82a and the second contact portion 82a is defined as the distance B1 between the first contact portion 82a and the second contact portion 82a passing through the center of the second axis 102 on a plane perpendicular to the second axis 102. This is the maximum distance between the second contact portions 82a.

Further, in this embodiment, the primary transfer roller provided in the transfer device is configured to be able to move in a direction away from the photoreceptor. The primary transfer roller can be separated from the photoreceptor in conjunction with the operation of changing the posture of the pressing member by operating the lever portion 71a. A mechanism for separating the primary transfer roller from the photoreceptor will be explained.

As shown in FIG. 22(a), a special color transfer nip NT is formed between the primary transfer roller 7T and the photoreceptor 3T via the intermediate transfer belt 2. The primary transfer roller 7C forms a cyan transfer nip NC between the primary transfer roller 7C and the photoreceptor 3C via the intermediate transfer belt 2. The primary transfer roller 7M forms a magenta transfer nip NM with the photoreceptor 3M via the intermediate transfer belt 2. The primary transfer roller 7Y forms a yellow transfer nip NY between the primary transfer roller 7Y and the photoreceptor 3Y via the intermediate transfer belt 2. A black transfer nip NK is formed between the primary transfer roller 7K and the photoreceptor 3K via the intermediate transfer belt 2.

The transfer device 20 includes the most upstream primary transfer section 201 disposed at the most upstream side in the running direction of the intermediate transfer belt 2, the most downstream primary transfer section 203 disposed at the most downstream side, and the most upstream primary transfer section 201. The central primary transfer unit 202 includes a plurality of primary transfer parts disposed between the central primary transfer unit 202 and the most downstream primary transfer part 203 . In this embodiment, the most upstream primary transfer unit 201 transfers a black toner image using a black transfer nip NK, and the central primary transfer unit 202 transfers a cyan toner image, magenta The most downstream primary transfer unit 203 transfers the special color toner image and the yellow toner image onto the intermediate transfer belt 2 using the special color transfer nip NT. In the following description, the upstream side or downstream side of the intermediate transfer belt 2 in the running direction will also be simply referred to as the upstream side or downstream side.

In the traveling direction of the intermediate transfer belt 2, a driven roller 21A as a tension member and a detection sensor 22 as a detection mechanism are provided between the primary transfer roller 7C and the primary transfer roller 7T. The driven roller 21A stretches the intermediate transfer belt 2. The detection sensor 22 detects the scale on the intermediate transfer belt 2 and detects the running speed of the intermediate transfer belt 2. By controlling the speed of the intermediate transfer belt 2 based on this detection result, it is possible to suppress positional deviation of the toner images of each color transferred to the intermediate transfer belt 2.

In FIG. 22(a), the primary transfer roller 7K provided in the most upstream primary transfer section 201 is the most upstream primary transfer member, and the primary transfer rollers 7Y, 7M, and 7C provided in the central primary transfer unit 202 are the central primary transfer members. The primary transfer roller 7T provided in the most downstream primary transfer section 203 is the most downstream primary transfer member. The running direction of the intermediate transfer belt 2 is the direction shown by arrow A in FIG. 22(a). Further, each of the primary transfer rollers 7K, 7Y, 7M, and 7C on the upstream side of the primary transfer roller 7T is also an upstream primary transfer member.

In this embodiment, the most upstream primary transfer section 201 can transfer the special color, and the most downstream primary transfer section 203 can also transfer the special color. This makes it possible to transfer special color toners in the required order.

In the running direction of the intermediate transfer belt 2, a driven roller 21A as a second tension roller and a detection sensor 22 as a detection mechanism are provided between the primary transfer roller 7C and the primary transfer roller 7T. The driven roller 21A stretches the intermediate transfer belt 2. The detection sensor 22 detects the scale on the intermediate transfer belt 2 and detects the running speed of the intermediate transfer belt 2. By controlling the speed of the intermediate transfer belt 2 based on this detection result, it is possible to suppress positional deviation of the toner images of each color transferred to the intermediate transfer belt 2.

In the transfer device 20 of this embodiment, each primary transfer roller 7 contacts or separates from the photoreceptor 3 via the intermediate transfer belt 2 depending on the mode during image formation. For example, as shown in FIG. 22(b), all the primary transfer rollers 7T can be separated from the photoreceptor 3T. FIG. 22(b) is an example, and the contact and separation states of the primary transfer rollers 7 of the most upstream primary transfer section 201, the central primary transfer unit 202, and the most downstream primary transfer section 203 can be switched.

In conjunction with the movement of the most downstream primary transfer roller 7T toward and away from the photoreceptor 3T, the driven roller 21A and the driven roller 33A, which serve as tensioning members for stretching the intermediate transfer belt 2, and the detection sensor 22 also move in the vertical direction in FIG. It moves in the direction of approaching and separating from the photoreceptor 3. The first contact/separation mechanism for bringing these members into contact/separation will be described below with reference to FIGS. 15 and 23 to 30. Although FIG. 15 is a diagram in the above-mentioned retracted state, it is also a diagram in which the primary transfer roller 7T is in the "contact" state. Note that although the following description shows a case where a special color toner image is transferred in the most downstream primary transfer section 203, a black toner image may also be transferred.

As shown in FIG. 15, a primary transfer roller 7T is provided at one end of the rotating member 34. As shown in FIG. The rotating member 34 is rotatably provided around a rotational fulcrum 34a. The rotating member 34 has a hole 34b at the end opposite to the side where the primary transfer roller 7T is provided. A pin 32b provided on the front slider 32 is inserted into the hole 34b. The spring 35 is fixed to the casing of the image forming apparatus, and urges the rotating member 34 to rotate clockwise in FIG. 15 about the rotational fulcrum 34a. Due to the biasing force of the spring 35, the primary transfer roller 7T is in contact with the intermediate transfer belt 2. Further, a driven roller 33A, which is one of the tensioning members for stretching the intermediate transfer belt 2, is provided at one end of the rotating member 33. The rotating member 33 is rotatably provided around a rotational fulcrum 33a. The rotating member 33 has a hole 33b at the end opposite to the side where the driven roller 33A is provided. An insertion portion 32a provided on the front slider 32 is inserted into the hole 33b. The insertion portion 32a is constructed by press-fitting a ball bearing into a shaft portion fixed to the front slider 32. Furthermore, the driven roller 21A is provided at one end of the rotating member 21. The rotating member 21 is rotatably provided around a rotational fulcrum 21a. The rotating member 21 receives a force from the spring 39 that causes it to rotate clockwise around the rotational fulcrum 21a.

The first contact/separation mechanism 91 is provided with a cam member 31 to which the driving force of the motor is transmitted. As shown in FIG. 23, the cam member 31 includes a cam 31A and a cam 31B, and is rotatably provided around a rotating shaft 31a. The cam 31B is a ball bearing having an outer ring, and is eccentric with respect to the rotating shaft 31a.

The cam 31A has a small diameter part, a medium diameter part, and a large diameter part each having a different diameter of 120 degrees. As shown in FIG. 24, the cam 31A contacts a cam follower 36 made of a ball bearing. The front slider 32 can be moved in the left-right direction in FIG. 15 by changing the surface of the cam 31A that contacts the cam follower 36 by rotating the cam 31A.

FIG. 25 is a diagram of the "separated" state in which the primary transfer roller 7T is separated from the photoreceptor.
The rotation of the cam 31A causes the front slider 32 to move to the right in FIG. 15, resulting in a "separated" state. In other words, when the front slider 32 moves rightward as shown in FIG. 15 → FIG. , the rotating members 33, 34, and 21 rotate counterclockwise, respectively. As a result, the driven roller 33A, the primary transfer roller 7T, and the driven roller 21A move downward in FIG. 25, which is the direction away from the photoreceptor. As the driven rollers 33A and 21A move, the tension position of the intermediate transfer belt 2 stretched between these rollers moves downward in FIG. 25.

Further, as the front slider 32 moves from FIG. 15 to FIG. 25, the detection sensor 22 moves downward in FIG. 25. Thereby, the detection sensor 22 can be moved in accordance with the stretched position of the intermediate transfer belt 2. A mechanism for moving this detection sensor 22 will be described below.

As shown in FIGS. 24 and 26, the first arm 37 grips the cam 31B at two locations: gripping portions 37c1 and 37c2. The rotation of the cam 31B causes the first arm 37 to rotate about the rotation fulcrum 37a. As the front slider 32 moves from FIG. 15 to FIG. 25, the first arm 37 rotates clockwise in FIG. 26 about the rotation fulcrum 37a.

As shown in FIG. 24, a thrust stopper member 60 is attached to the first arm 37 as a regulating member and a stopper member. The thrust stopper member 60 can regulate the direction of relative movement of the first arm 37 with respect to the cam 31B by regulating the position of the outer peripheral surface of the cam 31B by the regulating portion 60b. In other words, it is possible to prevent the first arm 37 from moving in a direction other than the direction along the outer peripheral surface of the cam 31B, for example, in a sliding direction with respect to the cam 31B.

FIG. 27 is a front perspective view of the periphery of the first arm 37 and the second arm 38. FIG. 28 is a perspective view of the back side of the first arm 37 and the second arm 38.

As shown in FIG. 27, the second arm 38 as the second link member has another elongated hole 38a and another elongated hole 38b at both ends thereof. One end 37b of the first arm 37 is inserted into another long hole 38a. As shown in FIG. 28, one end 37b of the first arm 37 has a bearing 40. As shown in FIG. The bearing 40 is provided so as to be relatively movable within the other elongated hole 38a. The bearing 40 is another insertion part for the other elongated hole 38a.

As shown in FIG. 27, a bearing 41 is inserted into the long hole 38b. The bearing 41 is fixed to a first sensor bracket 43 as a holding member by a step screw 42. The bearing 41 is provided so as to be movable within the elongated hole 38b. The bearing 41 is an insertion portion into the elongated hole 38b.

The rotation of the cam member 31 moves the front slider 32 from the state shown in FIG. 15 to the right side in FIG. 15 to bring the most downstream primary transfer section 203 into the "separated" state, thereby rotating the cam 31B and moving the first arm 37 rotates clockwise around a rotational fulcrum 37a. As a result, one end 37b of the first arm 37 moves downward in FIG. 15. As a result, as shown in FIG. 25, the one end 37b moves to one end of the other elongated hole 38a and comes into contact with the wall portion forming the other elongated hole 38a, and the second arm 38 is pulled toward the lower left in FIG. . As a result, the bearing 41 moves relatively to one end of the elongated hole 38b and comes into contact with a wall portion forming the elongated hole 38b. Then, the second arm 38 pulls the first sensor bracket 43 toward the lower left in FIG. 25.

FIG. 29 is a diagram showing the configuration around the first sensor bracket 43 and the detection sensor 22, and is a diagram with the rotating member 21 removed from FIG. 15 and the like. In FIG. 29, the detection sensor 22 and the second sensor bracket 44 are illustrated in a simplified manner for convenience.

As shown in FIG. 29, the first sensor bracket 43 is rotatably provided around a rotation fulcrum 43a. The first sensor bracket 43 receives a force from a spring 45 fixed to the casing of the image forming apparatus in a direction that causes it to rotate counterclockwise in FIG. 29 about a rotational fulcrum 43a. Further, a regulation bracket 63 is fixed to the first sensor bracket 43. The pin 32d of the front slider 32 is inserted into the hole 63a of the regulation bracket 63. In the "contact" state shown in FIG. 15, the pin 32d comes into contact with the wall forming the hole 63a, so that the front slider 32 moves clockwise in FIG. Adds rotational force.

A second sensor bracket 44 is fixed to the first sensor bracket 43 via a stud 43b provided on the first sensor bracket 43. The second sensor bracket 44 holds the detection sensor 22. The second sensor bracket 44 has a hook 44a to which one end of the spring 62 (see FIG. 15) is attached, a first contact portion 44b, and a second contact portion 44c.

In the "contact" state shown in FIG. 15, the second sensor bracket 44 is biased by the spring 62 and moves in a clockwise direction around the rotation fulcrum 43a, and the first contact part 44b It is positioned at a position where it comes into contact with a stud 64 provided in the housing of the forming device.

In addition, in the "separated" state of FIG. 25, the pin 32d moves to the right, so that the force with which the pin 32d presses the regulation bracket 63 to the left in FIG. 29 is released, as shown in FIG. As described above, when the second arm 38 pulls the first sensor bracket 43 toward the lower left in FIG. 29, the first sensor bracket 43 rotates clockwise in FIG. 29 about the rotational fulcrum 43a. As a result, the second sensor bracket 44 fixed to the first sensor bracket 43 via the stud 43b moves upward in FIG. 29, and the detection sensor 22 also moves upward in FIG. 29. At this time, as shown in FIG. 30, the second sensor bracket 44 is positioned at a position where the second contact portion 44c of the second sensor bracket 44 abuts against the positioning portion 21b of the rotating member 21. That is, upward movement of the second sensor bracket 44 and the detection sensor 22 in FIG. 29 is restricted, and the detection sensor 22 is positioned.

As described above, in this embodiment, by moving the front slider 32 to the right in FIG. 25 from FIG. 15 to FIG. 25, the primary transfer roller 7T, driven roller 21A, driven roller 33A, and detection sensor 22 are activated. Move in the direction away from the photoreceptor.

Although the above explanation shows the case where the front slider 32 is moved by the driving force of the motor, the front slider 32 can also be moved to the right in FIG. 25 by operating force on the lever portion 71a. The movement of the front slider 32 by operating the lever portion 71a will be explained.

By moving the lever portion 71a from the retracted position to the holding position as shown in FIGS. 3 to 4 described above, the lever fixing shaft 71b, which is the rotation fulcrum of the lever portion 71a, rotates as shown in FIGS. 15 to 16. In the middle of this, the cam 80 comes into contact with a cam follower 81 attached to the front slider 32, and moves the front slider 32 to the right side as shown in FIG. 15→FIG. 16 via the cam follower 81. As a result, as in the case where the cam member 31 is rotated by the motor and moved from the "contact" state to the "separated" state as shown in FIG. 15→FIG. 15, the primary transfer roller 7T, the driven roller 21A, the driven roller 33A, and the detection sensor 22 can each be moved in a direction away from the photoreceptor.

In this embodiment, in conjunction with the operation of changing the holding member 101 to the holding position, the tensioning member that stretches the primary transfer roller and the intermediate transfer belt can be moved in the direction away from the photoreceptor. . Thereby, the number of work procedures during maintenance can be reduced.

The cam 80, which is the fixing member of this embodiment, only needs to come into contact with the cam follower 81 in a predetermined area where it changes from the holding position and the retracted position to the holding position, and it is not necessary to have a cam surface in the entire circumferential direction. Moreover, if the holding member 101 is only to be held in the holding position, the fixing member should just be able to abut the cam follower 81 in the holding position phase and fix the lever fixing shaft 71b in the holding position phase. In this case, the fixing member does not necessarily have to have a cam shape as in this embodiment, for example, it can be a protrusion extending in a specific circumferential direction of the lever fixing shaft 71b.

By the way, the PCDU 10 (see FIG. 1) provided in the image forming apparatus 1 is detachably provided to the main body of the image forming apparatus 1. A regulating member that regulates the movement of the PCDU 10 in the removal direction is provided in the transfer device 20. This regulating member will be explained below.

As shown in FIG. 31, the PCDU 10 is arranged above the transfer device 20. By moving the PCDU 10 in a direction perpendicular to the paper plane of FIG. 31, the PCDU 10 can be attached to and detached from the main body of the image forming apparatus.

The detection sensor 22 provided in the transfer device 20 is arranged at a position where it interferes with the PCDU 10 during the removal operation of the PCDU 10. Therefore, when attaching or detaching the PCDU 10, the detection sensor 22 is separated from the PCDU 10. The detection sensor 22 is thus provided in the transfer device 20 and is a part that moves toward and away from the PCDU 10 . Note that the direction of moving away from the PCDU 10 is the arrow D1 direction in FIG. 31, and the direction of approaching the PCDU 10 is the arrow D2 direction of FIG.

The transfer device 20 has a regulating member 72 . The regulating member 72 in FIG. 31 is provided at a position that interferes with the PCDU 10 during the removal operation of the PCDU 10. That is, it is arranged at a position overlapping with the PCDU 10 on the plane of FIG. 31, which is a plane perpendicular to the direction in which the PCDU 10 is removed. By interfering with the PCDU 10, the regulating member 72 regulates the movement of the PCDU 10 toward the front in the paper of FIG. 31, which is the removal direction from the image forming apparatus.

The regulating member 72 abuts on the PCDU 10 at a position before the position where the PCDU 10 abuts the detection sensor 22 in the removal direction, and regulates the removal of the PCDU 10 . Although FIG. 31 shows a case where the restriction member 72 is provided in the PCDUs 10T and 10C, the restriction member 72 may be provided in any position of the five PCDUs 10 described above.

By rotating the release lever 71 from FIG. 31 to FIG. 32, the detection sensor 22 can be moved in the direction away from the photoreceptor, as described above. Thereby, as shown in FIG. 32, the detection sensor 22 can be placed at a position where it does not interfere with the PCDU 10 during the removal operation of the PCDU 10. Further, by rotating the release lever 71 from FIG. 31 to FIG. 32, the regulating member 72 can be placed in a position where it does not interfere with the PCDU 10 during the removal operation of the PCDU 10. Note that the position of the release lever 71 in FIG. 31 is the position in which the pressing member 101 shown in FIG. 3 and the like described above is in the retracted position, and the position in FIG. 32 is the position in which the pressing member 101 is in the pressing position.

Next, how the regulating member 72 changes its posture in conjunction with the operation of the release lever 71 will be described.

As described above, the operator can rotate the release lever 71 from the position shown in FIG. 3 to the position shown in FIG. 4 by operating the release lever 71. Thereby, the holding member 101 can be moved from the retracted position to the holding position. Further, by rotating the release lever 71 from the retracted position shown in FIG. 31 to the pressed position shown in FIG. 32, the regulating member 72 can be rotated. As described above, the rotation of the release lever 71 causes the first link member 73 to rotate counterclockwise around the lever fixing shaft 71b as shown in FIGS. 8 to 9. This rotational force is transmitted to the fourth link member 76 via the second link member 74 and the third link member 75, and the fourth link member 76 moves to the left in FIG.

The regulating members 72C and 72T have one end attached to the fourth link member 76. Therefore, as the fourth link member 76 moves from FIG. 8 to FIG. 9, the regulating members 72C and 72T change their postures.

A long hole 72a is provided in the regulating members 72C and 72T. Shafts 84 and 85 fixed to the transfer frame are inserted into the long holes 72a, respectively. The postures of the regulating members 72C and 72T are regulated within a range in which the shaft 84 or 85 can move relatively within the elongated hole 72a. Due to this regulation, the regulation members 72C and 72T reciprocate in the posture shown in FIG. 8 or 9 as the fourth link member 76 moves. In other words, it moves back and forth between a position where it interferes with the PCDU 10 in FIG. 31 and a position where it does not interfere with the PCDU in FIG. 32.

As described above, in this embodiment, by operating the release lever 71, the restriction on movement of the PCDU in the removal direction by the restriction member 72 can be canceled. That is, in this embodiment, the operation of the release lever 71 releases the restriction of the restriction member 72, moves the pressing member 101 (see FIG. 3) from the retracted position to the pressing position, and moves the primary transfer roller 7 and the detection sensor 22 (see FIG. 22). ) can be simultaneously moved in the direction away from the photoreceptor 3. In other words, the PCDU 10 can be removed from the main body of the image forming apparatus 1 by simultaneously releasing the restriction of the restriction member 72, moving the pressing member 101 to the pressing position, and moving the detection sensor 22 in the direction away from the photoreceptor 3. It can be a state. Since these operations can be performed only by operating the release lever 71, the operation of removing the PCDU 10 from the main body of the image forming apparatus 1 can be simplified. Further, it is possible to prevent the removal operation of the PCDU 10 from starting in a state where a specific member is not moved, such as by neglecting to release the restriction of the restriction member 72. However, these operations do not necessarily need to be linked.

In the above description, the primary transfer roller 7T of the most downstream primary transfer portion moves away from the photoreceptor in conjunction with the pressing member 101, but any other primary transfer roller may move away from the photoreceptor. .

Next, a second contact/separation mechanism 92 as a second moving mechanism that brings the primary transfer rollers 7C, 7M, 7Y provided in the central primary transfer unit 202 into contact with and separate from the intermediate transfer belt 2; A third contact/separation mechanism 93 as a third moving mechanism that brings the primary transfer roller 7K provided in the transfer section 201 into contact with/separates from it will be described with reference to FIG. 33.

As shown in FIG. 33, the second contact/separation mechanism 92 includes rotating members 46 to 48, a cam 51, and a cam follower 52. The third contact/separation mechanism 93 includes a rotating member 49, a cam 53, and a cam follower 54. The second contact/separation mechanism 92 includes a motor as a drive source for rotating the cam 51, and the third contact/separation mechanism 93 includes a motor as a drive source for rotating the cam 53.

Rotating members 46, 47, 48, and 49 are provided rotatably about rotational supports 46a, 47a, 48a, and 49a. A primary transfer roller 7C is provided at one end of the rotating member 46. A primary transfer roller 7M is provided at one end of the rotating member 47. A primary transfer roller 7Y is provided at one end of the rotating member 48. A primary transfer roller 7K is provided at one end of the rotating member 49. Each of the rotating members 46 to 49 is urged by a spring to rotate clockwise in FIG. 33, and each primary transfer roller 7 is brought into contact with the photoreceptor via the intermediate transfer belt 2.

The rotation of the cam 51 causes the cam follower 52 to rotate, and the front slider 50 of the most upstream primary transfer section 201 moves to the right in FIG. 33. As a result, the ends of the rotating members 46 to 48 on the side opposite to the side on which the primary transfer roller 7 is provided are pressed, and each of the rotating members 46 to 48 rotates counterclockwise in FIG. 33 against the biasing force of the spring. do. As a result, each primary transfer roller 7C, 7M, 7Y is separated from each photoreceptor. Further, the rotation of the cam 53 causes the cam follower 54 to rotate, and presses the end of the rotating member 49 on the side opposite to the side on which the primary transfer roller 7K is provided. As a result, the rotating member 49 rotates counterclockwise in FIG. 33 against the biasing force of the spring, and the primary transfer roller 7K separates from the photoreceptor. As described above, the primary transfer roller 7K of the most upstream primary transfer section 201 and each of the primary transfer rollers 7C, 7M, and 7Y of the central primary transfer unit 202 independently approach and separate from each photoreceptor.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various changes can be made without departing from the gist of the present invention.

In the above description, the operation member is provided in the transfer device, but it may also be provided in an appropriate position within the image forming device, such as in the casing of the image forming device.

In addition to paper P (plain paper), recording media include cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheets, plastic films, prepregs, copper foil, etc. included.

Aspects of the present invention are, for example, as follows.
<1>
a belt member that runs around;
a pressing member that presses the belt member;
A belt device comprising: a transmission section that transmits a driving force to the pressing member,
The pressing member is provided so as to be able to reciprocate between a pressing position in which the belt member is pressed and a retracted position in which the pressing member is retracted from the belt member,
The transmission section transmits a driving force to the pressing member, so that the pressing member is changed to the retracted position,
The belt device is characterized in that the holding member changes its posture to the holding position side due to its own weight. <2>
a first shaft that transmits driving force to the transmission section by its own rotation;
The belt device according to <1>, further comprising a fixing member provided on the first shaft and fixing the phase of the first shaft by applying force to the first shaft in the holding position. 3>
The transmission section is
a first link member having the first axis as a rotation axis;
a first cam that transmits a driving force to the pressing member by rotation of the first cam;
one or more other link members that transmit driving force between the first link member and the first cam;
<4> The belt device according to <2>, further comprising a biasing member that biases the first link member in a direction of a rotational phase of the first link member in the retracted position.
The belt device according to <2> or <3>, comprising an operating member fixed to the first shaft,
<5> The belt device is capable of rotating the first shaft by operating the operating member.
The belt device according to any one of <1> to <4>, wherein the belt member has at least an elastic layer and is composed of a plurality of layers made of different materials. <6>
The second shaft is constituted by a plurality of shaft parts,
<7> The belt device according to <3>, or <4> according to <3>, or <5> according to <3>, wherein the plurality of shaft parts are connected via the first cam. ＞
The transmission section is
a second shaft to which the first cam is provided and a driving force is transmitted from the other link member;
The belt device according to <3>, or <4> according to <3>, or <5> according to <3>, or <6>, having a cam follower that swings by rotation of the first cam. There it is,
The cam follower has a first abutted part and a second abutted part that abut the first cam in the retracted attitude or the pressed attitude,
The first cam is a belt device disposed between the first abutted part and the second abutted part <8>
The first cam has a first contact portion and a second contact portion that contact the first contact portion and the second contact portion,
The belt device according to <7>, wherein the distance between the first abutted part and the second abutted part is smaller than the distance between the first abutted part and the second abutted part. ＞
A transfer device including the belt device according to any one of <1> to <8>.
<10>
The transfer device according to <9>, comprising a transfer member,
In the transfer device, the first shaft rotates in a direction in which the holding member changes from the retracted position to the holding position, thereby moving the transfer member in a direction away from the latent image carrier.
<11>
An image forming apparatus including the transfer device described in <9> or <10>.

1 Image forming device 2 Intermediate transfer belt (belt member or intermediate transfer body)
3 Photoreceptor (latent image carrier)
7 Primary transfer roller (primary transfer member)
20 Transfer device (belt device)
20A inner cover (transfer frame)
22 Detection sensor (contact/separation part)
71 Release lever (operating member)
71a Lever part (operation part)
71b Lever fixed shaft (first shaft)
73 First link member 74 Second link member (other link member)
75 Third link member (other link member)
76 Fourth link member (other link member)
77 Fifth link member (other link member)
78 Spring (biasing member)
80 Cam (fixed member)
82 First cam 83 Cam follower 101 Holding member 102 Second shaft 1021 Center side shaft part (shaft part forming the second shaft)
1022, 1023 End-side shaft portion (shaft portion constituting the second shaft)

Patent No. 6394151

Claims (11)

a belt member that runs around;
a pressing member that presses the belt member;
A belt device comprising: a transmission section that transmits a driving force to the pressing member,
The pressing member is provided so as to be able to reciprocate between a pressing position in which the belt member is pressed and a retracted position in which the pressing member is retracted from the belt member,
The transmission section transmits a driving force to the pressing member, so that the pressing member is changed to the retracted position,
The belt device is characterized in that the holding member changes its posture to the holding position due to its own weight. a first shaft that transmits driving force to the transmission section by its own rotation;
The belt device according to claim 1, further comprising a fixing member provided on the first shaft and fixing the phase of the first shaft by applying force to the first shaft in the holding position. The transmission section is
a first link member having the first axis as a rotation axis;
a first cam that transmits a driving force to the pressing member by rotation of the first cam;
one or more other link members that transmit driving force between the first link member and the first cam;
The belt device according to claim 2, further comprising a biasing member that biases the first link member in a direction of a rotational phase of the first link member in the retracted position. The belt device according to claim 2, further comprising an operating member fixed to the first shaft,
A belt device capable of rotating the first shaft by operating the operating member. The belt device according to claim 1, wherein the belt member has at least an elastic layer and is composed of a plurality of layers made of different materials. The second shaft is constituted by a plurality of shaft parts,
The belt device according to claim 3, wherein the plurality of shaft portions are connected via the first cam. The transmission section is
a second shaft to which the first cam is provided and a driving force is transmitted from the other link member;
4. The belt device according to claim 3, further comprising a cam follower that swings due to rotation of the first cam,
The cam follower has a first abutted part and a second abutted part that abut the first cam in the retracted attitude or the pressed attitude,
A belt device in which the first cam is arranged between the first abutted part and the second abutted part. The first cam has a first contact portion and a second contact portion that contact the first contact portion and the second contact portion,
The belt device according to claim 7, wherein a distance between the first abutted part and the second abutted part is smaller than a distance between the first abutted part and the second abutted part. A transfer device comprising the belt device according to any one of claims 1 to 8. The transfer device according to claim 9, comprising a transfer member,
A transfer device in which the first shaft rotates in a direction in which the pressing member changes from the retracted position to the pressing position, thereby moving the transfer member in a direction away from the latent image carrier. An image forming apparatus comprising the transfer device according to claim 9.

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