JP2010262050A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce faulty transfer by absorbing the speed variations of a transfer member. <P>SOLUTION: The image forming apparatus includes an image carrier drum which has a rotary shaft and on which an image is carried; a transfer roller 61 which has a rotary shaft 61a; a cylindrical base material 61b having a recess formed in the axial direction of the rotary shaft 61a; a transfer material grasping member disposed in the recess and grasping transfer material; an elastic transfer material supporting part 61c supporting the transfer material, and abuts on the image carrier drum and transfers an image carried on the image carrier drum to the transfer material; a first abutting member 70, which is disposed in the axial direction of the recess and supported on the rotary shaft 61a of the transfer roller 61; and a second abutting member 41c, which is supported on the rotary shaft of the image carrier drum via rolling bearing and abuts against the first abutting member 70. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus related to electrophotography.

  Conventionally, a transfer roller having an elastic layer as a transfer roller of an image forming apparatus has been disclosed (Patent Document 1). The image forming apparatus described in Patent Document 1 describes a shape that seems to be a recess, but does not mention its function.

Special Table 2000-508280

  Conventionally, when there is a recess in the secondary transfer roller, the transfer medium that forms the nip portion with the secondary transfer roller corresponds to the recess of the secondary transfer roller, or is in contact with a portion other than the recess The rotational load of the secondary transfer roller is different, and the rotation unevenness of the secondary transfer roller caused by the rotation is transmitted to the transfer medium, and the transfer image at the primary transfer portion and the latent image at the exposure position of the photosensitive member may be disturbed.

  In order to solve the above-described problem, an object of the present invention is to provide an image forming apparatus that absorbs fluctuations in the speed of a transfer member, thereby reducing transfer defects and forming an image satisfactorily.

  An image forming apparatus according to the present invention includes an image carrier drum having a rotation shaft, on which an image is carried, a rotation shaft, a cylindrical base material having a recess formed in an axial direction of the rotation shaft, and the recess. A transfer material holding member for holding the transfer material; and an elastic transfer material support portion for supporting the transfer material, wherein the image carried on the image carrier in contact with the image carrier drum is transferred to the transfer material. A transfer roller for transfer to the shaft, a first contact member disposed in the axial direction of the recess and supported by the rotation shaft of the transfer roller, and a rotation shaft of the image carrier drum via a rolling bearing. And a second abutting member that is supported and abutted against the first abutting member.

Further, the image forming apparatus of the present invention includes an image carrier belt on which an image is carried, a rotation shaft, a tension roller that stretches the image carrier belt, a rotation shaft, and an axial direction of the rotation shaft A cylindrical base material having a concave portion formed thereon, a transfer material gripping member disposed in the concave portion for gripping the transfer material, and an elastic transfer material support portion for supporting the transfer material, and the stretching roller and the image A transfer roller for contacting the image carrier belt by contacting with the carrier belt and transferring the image to the transfer material, and an axial direction of the recess, and supported by a rotation shaft of the transfer roller And a second contact member that is supported by a rotating shaft of the tension roller via a rolling bearing and that contacts the first contact member. And

  The image forming apparatus further includes a bias applying unit that applies a bias to the transfer roller.

  The rolling bearing is an insulating member.

  Further, the first contact member is provided with an elastic member at a contact portion with the second contact member.

  According to the present invention, in order to solve the above-described problems, it is possible to provide an image forming apparatus that absorbs fluctuations in the speed of the transfer member, thereby reducing transfer defects and forming an image satisfactorily.

1 is a diagram illustrating a first embodiment of an image forming apparatus. It is a figure which shows 2nd Embodiment of an image forming apparatus. It is a figure which shows 3rd Embodiment of an image forming apparatus. It is a figure which shows a secondary transfer roller. It is the figure which expanded a part of FIG. It is a figure which shows the state by which the transfer material is not supplied to the secondary transfer roller. It is a figure which shows the state which the gripper of a secondary transfer roller is going to hold | grip a transfer material. It is a figure which shows the state in which the gripper of a secondary transfer roller is holding the transfer material. It is a figure which shows the state which the gripper of a secondary transfer roller spaces apart, and the protrusion nail has protruded the transfer material. It is a figure which shows the rotating shaft and base material of a secondary transfer roller. It is a figure which shows the rubber sheet as an elastic member of a secondary transfer roller. It is sectional drawing which shows the structure which winds a rubber sheet around a secondary transfer roller. It is sectional drawing which shows the relationship between a secondary transfer roller, a belt drive roller, an intermediate transfer belt, and a contact member. It is a figure which shows the contact member and contact member support part of Example 1. FIG. It is a figure which shows the contact member and contact member support part of Example 2. FIG. It is a figure which shows the structure which applies a bias to a secondary transfer roller.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing main components constituting the image forming apparatus according to the first embodiment of the present invention. The developing devices 30Y, 30M, 30C, and 30K as the developing units are arranged below the image forming device, and the transfer unit, with respect to the intermediate transfer belt 40 as the image carrier belt arranged at the center of the image forming device. The secondary transfer unit 60, the fixing unit 90, and the like are arranged in the upper part of the image forming apparatus. In particular, since the fixing unit 90 is laid out above the intermediate transfer belt 40, the installation area of the entire image forming apparatus can be suppressed.

  Exposure units 12Y, 12M, and 12C such as corona chargers 11Y, 11M, 11C, and 11K, and LED arrays are formed around the photoreceptors 10Y, 10M, 10C, and 10K as latent image carriers in order to form an image with toner. , 12K, etc. The photoconductors 10Y, 10M, 10C, and 10K are uniformly charged by the corona chargers 11Y, 11M, 11C, and 11K, and the exposure units 12Y, 12M, 12C, and 12K perform exposure based on the input image signals. Then, electrostatic latent images are formed on the charged photoreceptors 10Y, 10M, 10C, and 10K.

  The developing devices 30Y, 30M, 30C, and 30K are roughly composed of developing rollers 20Y, 20M, 20C, and 20K as developer carriers, yellow (Y), magenta (M), cyan (C), and black (K). Developer containers (reservoirs) 31Y, 31M, 31C, 31K for storing the liquid developers of the respective colors, and the liquid developers of the respective colors from the developer containers 31Y, 31M, 31C, 31K to the developing rollers 20Y, 20M, 20C, 20K. An anilox roller 32Y, 32M, 32C, 32K or the like as a developer supply member that is a coating roller to be coated is provided, and electrostatic latent images formed on the photoreceptors 10Y, 10M, 10C, 10K by liquid developers of various colors are provided. develop.

  The primary transfer units 50Y, 50M, 50C, and 50K transfer images formed on the photoreceptors 10Y, 10M, 10C, and 10K to the photoreceptors 10Y, 10M, 10C, and 10K, and primary transfer rollers 51Y, 51M, 51C, and 51K. This is a portion to be transferred to the intermediate transfer belt 40 through the nip portion.

  The intermediate transfer belt 40 is a belt formed of a seamless elastic member such as rubber, and is stretched around a belt driving roller 41 and a tension roller 42 as stretch rollers, and the primary transfer portions 50Y, 50M, 50C, and 50K. Thus, the belt is driven to rotate by the belt driving roller 41 while contacting the photoconductors 10Y, 10M, 10C, and 10K. The primary transfer portions 50Y, 50M, 50C, and 50K are arranged such that the primary transfer rollers 51Y, 51M, 51C, and 51K are opposed to each other with the photoreceptors 10Y, 10M, 10C, and 10K and the intermediate transfer belt 40 interposed therebetween. The developed toner images of the respective colors on the photoreceptors 10Y, 10M, 10C, and 10K are sequentially superimposed and transferred onto the intermediate transfer belt 40 using the contact position with 10M, 10C, and 10K as a transfer position, and a full-color toner image is transferred. Form.

  The tension roller 42 stretches the intermediate transfer belt 40 together with the belt driving roller 41 and the like, and the cleaning portion including the transfer belt cleaning blade 45 is applied at a portion where the tension roller 42 is stretched on the tension roller 42 of the intermediate transfer belt 40. The remaining toner and carrier on the intermediate transfer belt 40 are cleaned in contact with each other.

  The secondary transfer unit 60 includes a secondary transfer roller 61 and a secondary transfer roller cleaning blade 85 as transfer members. A rotation shaft 61 a of the secondary transfer roller 61 is rotatably supported by the arm 62. The arm 62 rotates and swings about a rotation shaft 62a supported by the apparatus main body (not shown) and is urged in a direction α (counterclockwise in FIG. 1) indicated by an arrow by a spring (not shown). The secondary transfer roller 61 is pressed against the belt drive roller 41 via the intermediate transfer belt 40 by the biasing force of the spring. The secondary transfer roller 61 rotates in the direction indicated by the arrow as the belt driving roller 41 rotates, and a transfer bias is applied by the bias generator 110, whereby the toner image on the intermediate transfer belt 40 is transferred at the transfer nip. The image is transferred to a transfer material S such as paper, film, or cloth that is conveyed along the transfer material conveyance path L. The secondary transfer unit 60 includes a transfer roller cleaning blade 85 that cleans the secondary transfer roller 61.

  A first suction device 210, a transfer material transport device 230, and a second suction device 270 are sequentially arranged downstream of the secondary transfer unit 60 in the transfer material transport path L, and transport the transfer material S to the fixing unit 90. In the fixing unit 90, the single-color toner image or the full-color toner image transferred onto the transfer material S such as paper is fused and fixed to the transfer material S such as paper.

  The transfer material S is supplied to the image forming apparatus by a paper feeding device (not shown). The transfer material S set in such a sheet feeding device is sent to the transfer material conveyance path L one by one at a predetermined timing. In the transfer material conveyance path L, the transfer material S is conveyed to the secondary transfer position by the gate rollers 101, 101 ′ and the transfer material guide 102, and a single color toner development image or full color toner development formed on the intermediate transfer belt 40 is obtained. The image is transferred to the transfer material S.

  As described above, the transfer material S that has been secondarily transferred is further transported to the fixing unit 90 by the transfer material transport means centered on the transfer material transport device 230. The fixing unit 90 includes a heating roller 91 and a pressure roller 92 urged toward the heating roller 91 with a predetermined pressure. The transfer material S is inserted between the nips to transfer the transfer material S. The single-color toner image or full-color toner image transferred above is fused and fixed to a transfer material S such as paper.

  Here, the developing device will be described, but since the configuration of the peripheral portion of the photosensitive member for each color and the developing device are the same, the following description is based on the peripheral portion of the photosensitive member for yellow (Y) and the developing device.

  The peripheral portion of the photoconductor is along the rotation direction of the outer periphery of the photoconductor 10Y with the corona charger 11Y as a reference, the exposure unit 12Y, the developing roller 20Y of the developing device 30Y, the first photoconductor squeeze roller 13Y, and the second photoconductor. A squeeze roller 13Y ′, a primary transfer unit 50Y, a charge eliminating unit (not shown), and a photoreceptor cleaning blade 18Y are arranged. In the image forming process, it is defined that the configuration arranged in the earlier stage in the order of the corona charger 11Y to the photoreceptor cleaning blade 18Y is upstream from the configuration arranged in the subsequent stage.

  The photoconductor 10Y is a photoconductor drum formed of a cylindrical member having a photosensitive layer such as an amorphous silicon photoconductor formed on the outer peripheral surface, and rotates in a clockwise direction in FIG.

  The corona charger 11Y is disposed upstream of the nip portion between the photoconductor 10Y and the developing roller 20Y in the rotation direction of the photoconductor 10Y, and a voltage is applied from a power supply device (not shown) to corona-charge the photoconductor 10Y. The exposure unit 12Y is disposed downstream of the corona charger 11Y and upstream of the nip portion with the developing roller 20Y in the rotational direction of the photoreceptor 10Y, and emits light onto the photoreceptor 10Y charged by the corona charger 11Y. Irradiation forms a latent image on the photoreceptor 10Y.

  The developing device 30Y includes a developing roller 20Y that carries the liquid developer, an anilox roller 32Y that is a coating roller for applying the liquid developer to the developing roller 20Y, and a liquid developer amount that is applied to the developing roller 20Y. A regulating blade 33Y for regulating the liquid developer, an auger 34Y supplying the anilox roller 32Y while stirring and conveying the liquid developer, a compaction corona generator 22Y for bringing the liquid developer carried by the developing roller 20Y into a compacted state, and development A developing roller cleaning blade 21Y that cleans the roller 20Y, and a developer container 31Y that stores a liquid developer in a state where toner is dispersed in a carrier at a weight ratio of approximately 20%.

  The liquid developer contained in the developer container 31Y is a low-concentration (about 1 to 3 wt%) and low-viscosity volatile at room temperature using a conventionally used Isopar (trademark: exon) as a carrier. Is a non-volatile liquid developer having a high concentration and high viscosity and having non-volatility at room temperature. That is, in the liquid developer in the present invention, a solid having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a thermoplastic resin is introduced into a liquid solvent such as an organic solvent, silicon oil, mineral oil, or edible oil. High viscosity (HAAKE RheoStress RS600, which is added together with a dispersant and has a toner solid content concentration of about 15 to 25%, and has a viscoelasticity of 30 to 30 at a shear rate of 1000 (1 / s) at 25 ° C. (About 300 mPa · s).

  Note that the arrangement order of members such as the photoconductors and developing devices corresponding to the respective colors Y, M, C, and K is not limited to the example illustrated in FIG. 1 and can be arbitrarily set.

  FIG. 2 is a diagram showing main components constituting the image forming apparatus according to the second embodiment of the present invention. In the image forming apparatus according to the second embodiment, the nip portion between the belt driving roller 41 and the secondary transfer roller 61 of the image forming apparatus according to the first embodiment is a winding system.

  The intermediate transfer belt 40 of the second embodiment is stretched around a belt driving roller 41, a first tension roller 42, a second tension roller 43, and a third tension roller 44, and is formed by primary transfer units 50Y, 50M, 50C, and 50K. It is rotationally driven by a belt driving roller 41 while abutting on the photoreceptors 10Y, 10M, 10C, and 10K. The primary transfer portions 50Y, 50M, 50C, and 50K are arranged such that the primary transfer rollers 51Y, 51M, 51C, and 51K are opposed to each other with the photoreceptors 10Y, 10M, 10C, and 10K and the intermediate transfer belt 40 interposed therebetween. The developed toner images of the respective colors on the photoreceptors 10Y, 10M, 10C, and 10K are sequentially superimposed and transferred onto the intermediate transfer belt 40 using the contact position with 10M, 10C, and 10K as a transfer position, and a full-color toner image is transferred. Form.

  In the secondary transfer unit 60, a secondary transfer roller 61 is disposed to face the belt driving roller 41 with the intermediate transfer belt 40 interposed therebetween, and a cleaning device including a secondary transfer roller cleaning blade 85 is disposed. Then, at a transfer position where the secondary transfer roller 61 is disposed, a single color toner image or a full color toner image formed on the intermediate transfer belt 40 is conveyed on a transfer material conveyance path L such as paper, film, cloth, etc. Transfer to transfer material.

  The first tension roller 42 stretches the intermediate transfer belt 40 together with the belt drive roller 41 and the like, and is composed of a transfer belt cleaning blade 45 at a portion stretched on the first tension roller 42 of the intermediate transfer belt 40. A cleaning unit is in contact with and arranged to clean the remaining toner and carrier on the intermediate transfer belt 40.

  FIG. 3 is a diagram showing main components constituting the image forming apparatus according to the third embodiment of the present invention. The image forming apparatus of the third embodiment uses a first intermediate transfer drum 46YM, a second intermediate transfer drum 46CK, and a third intermediate transfer drum 48 as an image carrier drum.

  The first intermediate transfer drum 46YM, the second intermediate transfer drum 46CK, and the third intermediate transfer drum 48 have a seamless rubber layer formed on a main body portion made of conductive metal. The first intermediate transfer drum 46YM contacts the photoconductors 10Y and 10M, and the second intermediate transfer drum 46CK contacts the photoconductors 10C and 10K. The first intermediate transfer drum 46YM sequentially transfers the developed toner images on the photoconductors 10Y and 10M with the contact position with the photoconductors 10Y and 10M as the transfer position, and the second intermediate transfer drum 46CK The developed toner images on the photoconductors 10C and 10K are sequentially superimposed and transferred using the contact position with the photoconductors 10C and 10K as a transfer position to form toner images. The third intermediate transfer drum 48 transfers the toner image on the first intermediate transfer drum 46YM using the contact position with the first intermediate transfer drum 46YM as the transfer position, and transfers the contact position with the second intermediate transfer drum 46CK. As a position, the toner image on the second intermediate transfer drum 46CK is transferred. The toner image carried on the third intermediate transfer drum 48 is transferred by the transfer unit 60 to the transfer material S being conveyed. The transfer unit 60 includes a transfer roller 61 as a transfer member. The transfer roller 61 is the same as the secondary transfer roller used in the first embodiment and the second embodiment.

  Further, a first intermediate transfer drum cleaning blade 47YM that cleans the first intermediate transfer drum 46YM contacts the first intermediate transfer drum 46YM. The contact position of the first intermediate transfer drum cleaning blade 47YM is after contact with the third intermediate transfer drum 48 and before contact with the photoconductors 10Y and 10M. Similarly, a second intermediate transfer drum cleaning blade 47CK that cleans the second intermediate transfer drum 46CK contacts the second intermediate transfer drum 46CK. The contact position of the second intermediate transfer drum cleaning blade 47CK is after contact with the third intermediate transfer drum 48 and before contact with the photoreceptors 10C and 10K. Further, a third intermediate transfer drum cleaning blade 49 as a cleaning unit that cleans the third intermediate transfer drum 48 contacts the third intermediate transfer drum 48. The contact position of the third intermediate transfer drum cleaning blade 49 is after contact with the transfer roller 61 and before contact with the first intermediate transfer drum 46YM and the second intermediate transfer drum 46CK.

  Although not shown, as another embodiment different from FIGS. 1 to 3, the image bearing member 10 is used as an image bearing member, and the image is transferred from the photosensitive member 10 to the transfer roller 61. The first contact member 70 may be provided in contact with the photoconductor 10 and supported by the same shaft with the same diameter as the transfer roller 61.

  Next, the configuration of the secondary transfer roller 61 will be described. 4 is a view showing the secondary transfer roller 61, and FIG. 5 is an enlarged view of a part of the secondary transfer roller 61. As shown in FIG. 6 to 9 show a process of protruding from the process before the transfer material S is gripped by the secondary transfer roller 61. 6 is a view showing a state where the transfer material S is not gripped by the secondary transfer roller 61, FIG. 7 is a view showing a state where the gripper 64 of the secondary transfer roller 61 is about to grip the transfer material S, and FIG. FIG. 9 shows a state in which the gripper 64 of the secondary transfer roller 61 is gripping the transfer material S. FIG. 9 shows a state in which the gripper 64 of the secondary transfer roller 61 is separated and the protruding claw 79 protrudes the transfer material S. FIG.

  The secondary transfer roller 61 has a concave portion 63 as a concave portion or a transfer material gripping member storage portion. As shown in FIG. 4, the recess 63 extends in the axial direction of the secondary transfer roller 61. Further, the secondary transfer roller 61 has a rubber sheet 61c as a transfer material support portion wound around the outer peripheral surface of the arc portion of the base material 61b. A resistance layer is formed on the outer peripheral surface of the arc portion of the secondary transfer roller 61 by the rubber sheet 61c.

  Further, a gripper 64 as a transfer material gripping member of the present invention and a gripper support portion 65 as a transfer material gripping member receiving portion on which the gripper 64 is seated are disposed in the recess 63. As shown in FIGS. 4 and 5, the grippers 64 are arranged along the axial direction of the secondary transfer roller 61, and any number can be provided.

  Each gripper 64 is formed of the same shape and / or the same size from a thin strip of metal. As an example, the gripper 64 is formed by being bent into a crank shape. As shown in FIG. 6, one end portion of the gripper 64 is a fixed end portion 64 a fixed to the rotation shaft, and the other end portion of the gripper 64 is a gripping portion 64 b that is seated on and away from the gripper support portion 65. . The gripping portion 64b grips the leading end portion Sa of the transfer material S with the gripper support portion 65 interposed therebetween. Further, the gripper 64 has a stepped portion 64c formed between the fixed end portion 64a and the gripping portion 64b.

  The peripheral length of the secondary transfer roller 61 is the length of the transfer material S in the transfer material movement direction having the maximum length in the transfer material movement direction among the types of transfer materials S used in the image forming apparatus 1 of this example. It is set larger than this. More specifically, the peripheral length of the secondary transfer roller 61 excluding the width of the concave portion 63 in the rotation direction of the secondary transfer roller is set to be larger than the maximum length of the transfer material S in the transfer material moving direction. As a result, the toner image on the intermediate transfer belt 40 is reliably transferred to the transfer material S having the maximum length in the transfer material moving direction.

  Further, as shown in FIG. 4, the secondary transfer roller 61 is provided with first contact members 70 and 71 that rotate integrally with the rotation shaft. The first contact members 70 and 71 have arcuate outer peripheral surfaces 70 a and 71 a concentric with the secondary transfer roller 61. The first contact members 70 and 71 contact the belt drive roller 41 directly or indirectly when the concave portion 63 of the secondary transfer roller 61 faces the position of the pressing nip with the belt drive roller 41.

  As shown in FIG. 4, a number of gripper support portions 65 corresponding to the grippers 64 are arranged along the axial direction of the secondary transfer roller 61. As shown in FIG. 6, these gripper support portions 65 are provided on the side wall 63 a side of the rear concave portion 63 in the rotation direction of the secondary transfer roller 61 of the concave portion 63.

  A protruding claw 79 is disposed in the recess 63. As shown in FIGS. 4 and 5, the protruding claw 79 is disposed along the axial direction of the secondary transfer roller 61. Any number of protruding claws 79 can be provided. Further, a gripper support portion 65 is disposed between adjacent protruding claws 79. Each protruding claw 79 is formed in the same shape and / or the same size from a thin strip of metal flat plate. Although not shown, the protruding claws 79 are integrally connected by a connecting portion and formed in a comb shape.

  Next, an image forming operation will be described.

  In the same manner as a conventionally known image forming apparatus using a liquid developer and each color photoconductor is disposed, each of the photoconductors 10Y, 10M, 10C, and 10K is supplied with the corona chargers 11Y, 11M, and 11C. , 11K are uniformly charged. Next, electrostatic latent images are written on the photoconductors 10Y, 10M, 10C, and 10K by the exposure units 12Y, 12M, 12C, and 12K. Next, the electrostatic latent images on the photoconductors 10Y, 10M, 10C, and 10K are developed with the liquid developer by the developing devices 30Y, 30M, 30C, and 30K to form toner images.

  The toner images of the photoconductors 10Y, 10M, 10C, and 10K are transferred to the intermediate transfer belt 40 by the primary transfer portions 50Y, 50M, 50C, and 50K. The toner image carried on the intermediate transfer belt 40 is transferred to the transfer material S being conveyed by the secondary transfer unit 60.

  The transfer of the toner image to the transfer material S in the secondary transfer unit 60 will be described in more detail.

  When the intermediate transfer belt 40 starts rotating by the rotation of the belt driving roller 41, the secondary transfer roller 61 also rotates. At this time, as shown in FIG. 6, the grip portion 64 b of the gripper 64 is seated on the gripper support portion 65. Further, the protruding claw 79 is set at the retracted position.

  As the toner image carried on the intermediate transfer belt 40 approaches the secondary transfer portion 60, each gripper 64 starts to be separated from the gripper support portion 65.

  As shown in FIG. 7, the gripper 64 set at the release position approaches the supply position of the transfer material S by the rotation of the secondary transfer roller 61. On the other hand, the transfer material S is supplied toward the secondary transfer roller 61, and the toner image carried on the intermediate transfer belt 40 approaches the secondary transfer unit 60. The rotation of the belt driving roller 41 and the rotation of the secondary transfer roller 61 are synchronously controlled so that the toner image of the intermediate transfer belt 40 is transferred to a predetermined position of the transfer material S at the transfer nip portion. At this time, the peripheral speed of the secondary transfer roller 61 (that is, the moving speed of the gripper 64) is set smaller than the moving speed of the transfer material S. Accordingly, the leading end of the transfer material S enters between the gripper 64 and the gripper support portion 65 and comes into contact with the stepped portion 64 c of the gripper 64. Then, due to the speed difference between the peripheral speed of the secondary transfer roller 61 and the moving speed of the transfer material S, the leading edge of the transfer material S comes into contact with the corner of the stepped portion 64c and is positioned with respect to the gripper 64, and the transfer. The tip end portion Sa of the material S bends.

  Subsequently, a part of the transfer material S comes into contact with the outer peripheral surface of the secondary transfer roller 61 and is curved along the outer peripheral surface. Each gripper 64 starts to approach the gripper support portion 65. Then, as shown in FIG. 8, each gripper 64 is in a state in which the leading end portion Sa of the transfer material S is pressed against and gripped by the gripper support portion 65. In this way, the transfer material S is positioned with respect to the secondary transfer roller 61 and reliably moves toward the transfer nip as the secondary transfer roller 61 rotates. At this time, the protruding claw 79 is held at the retracted position.

  The toner image on the intermediate transfer belt 40 is transferred to the transfer material S at the transfer nip. When the grip portion 64a of the gripper 64 and the leading end portion Sa of the transfer material S pass through the transfer nip, the gripper 64 starts to move away from the claw seat 65 as shown in FIG. 9, and the leading end portion Sa of the transfer material S is moved. To be released. Next, with the further rotation of the secondary transfer roller 61, the protruding claw 79 is set to the protruding position.

  On the other hand, the leading end portion Sa of the transfer material S released from the gripping by the gripper 64 is lightly pressed against the secondary transfer roller 61 side by air blowing from a blower 400 described later, and the secondary transfer roller 61 is pushed by a protruding claw 79. It is pressed in the direction away from the outer peripheral surface 61g. Thus, the leading end portion Sa of the transfer material S is guided toward the transfer material conveying means. The transfer material S clamped at the nip portion between the belt driving roller 41 and the secondary transfer roller 61 moves to the transfer material conveying means by further rotation of the belt driving roller 41 and the secondary transfer roller 61. That is, the transfer end portion of the transfer material S is peeled off while the toner image on the intermediate transfer belt 40 is secondarily transferred to the transfer material S. In the case of the transfer material S having a small elastic restoring force and a weak waist, the air blowing of the blower 400 can be omitted.

  Next, the secondary transfer roller will be described in detail.

  FIG. 10 is a diagram showing a rotating shaft 61a of the secondary transfer roller 61 and a base material 61b as a cylindrical base material.

  The rotation shaft 61a and the base material 61b of the secondary transfer roller 61 are made of a conductive metal material. As shown in FIG. 10, the secondary transfer roller 61 includes a base 61b including a recess 63, a base 61ba having a cylindrical cylindrical portion 61ba1, and flanges 61bb provided at both ends of the base 61ba. And the rotating shaft 61a are integrally formed.

  Next, the rubber sheet 61c as a transfer material support portion wound around the secondary transfer roller 61 will be described. The rubber sheet 61c according to the present invention preferably has a single layer, two layer structure, or three layer structure.

  FIG. 11 is a view showing a three-layer rubber sheet of the secondary transfer roller. As shown in FIG. 11, a rubber sheet 61c having a three-layer structure wound around the secondary transfer roller 61 includes a base material layer 61c1 as a first layer, an elastic layer 61c2 as a second layer, and a third layer. It has a surface layer 61c3 as a layer. An arrow in the figure is a direction from the center of the secondary transfer roller 61 toward the outer periphery.

  The tensile elastic modulus of the base material layer 61c1 is preferably larger than the tensile elastic modulus of the elastic layer 61c2.

Moreover, it is preferable that the film thickness of the base material layer 61c1, the film thickness of the elastic layer 61c2, and the film thickness of the surface layer 61c3 satisfy the following formula (1).
t2>t1> t3 (1)
However, t1 is the film thickness of the base material layer 61c1, t2 is the film thickness of the elastic layer 61c2, and t3 is the film thickness of the surface layer 61c3.

  The single layer is formed of a single rubber layer consisting only of the elastic layer 61c2. The two-layer structure is one in which the surface layer 61c3 is not used in the three-layer structure.

  In addition, as a material of the base material layer 61c1, for example, polyimide or polyamideimide can be given. Examples of the material of the elastic layer 61c2 include urethane rubber, silicon rubber, fluorine rubber, butyl rubber, and acrylic rubber. Furthermore, examples of the material for the surface layer 61c3 include fluororubber and fluororesin.

  Next, a configuration for winding a rubber sheet around the secondary transfer roller 61 will be described. FIG. 12 is a cross-sectional view showing a configuration in which a rubber sheet is wound around the secondary transfer roller.

  The secondary transfer roller 61 has a recess 63. As shown in FIG. 12, the recess 63 extends in the direction of the rotation shaft 61 a of the secondary transfer roller 61. The secondary transfer roller 61 has a rubber sheet 61c wound around the outer peripheral surface of the arc portion of the base material 61b. A resistance layer is formed on the outer peripheral surface of the arc portion of the secondary transfer roller 61 by the rubber sheet 61c. The rubber sheet 61c is bonded and fixed to the base 61 only by having both end portions 61d and 61e fixed to the wall surfaces 61b1 and 61b2 in the recesses formed in the base 61b and the other portions are wound around. Not. For example, the plates 61h and 61j may be extended in the direction of the rotation shaft 61a on both ends 61d and 61e of the rubber sheet 61c, and fastened to the base 61b with screws 61k or screws. The plates 61h and 61j are respectively provided with convex portions 61h1 and 61j1, and the convex portions 61h1 and 61j1 are recessed into the rubber sheet 61c, so that the plates 61h and 61j are firmly fixed. The fixing of the both end portions 61d and 61e of the rubber sheet 61c to the recess 63 is not limited to this, and other methods may be used.

  Further, the image forming apparatus may be configured to transfer directly from the photoconductors 10Y, 10M, 10C, and 10K as image carriers to the transfer roller 61.

  As shown in FIG. 12, the secondary transfer roller 61 according to the present invention fixes both end portions 61d and 61e of the rubber sheet 61c to the wall surfaces 61b1 and 61b2 in the recesses formed in the base material 61b, and the other portions are It is only wrapped and not glued or fixed. Therefore, while the secondary transfer roller 61 forms the nip portion with the belt driving roller 41, the rubber sheet 61c may be distorted due to the accumulated stress due to the nip pressure. In addition, since the rubber sheet 61c has a multilayer structure, the hardness varies depending on the layer, and distortion is more likely to occur.

  Therefore, in the secondary transfer roller 61 according to the present invention, it is preferable that the opening width of the concave portion 63 of the secondary transfer roller 61 is larger than the nip width of the nip portion.

  In addition, when the belt driving roller 41 and the recess 63 face each other, the secondary transfer roller 61 must be accurately positioned with respect to the belt driving roller 41.

  Therefore, as shown in FIGS. 1, 2, and 3, the secondary transfer roller 61 is urged by a spring (not shown) in a direction in which it is pressed against the belt driving roller 41 or the third intermediate transfer drum 48, and FIG. It is preferable to form the first contact members 70 and 71 shown.

  Next, the first contact member 70 will be described. Although the first contact member 70 has been described here, the contact member 71 has the same configuration.

  The first abutting member 70 has an arcuate outer peripheral surface 70 a concentric with the circle of the outer shape line 61 f of the secondary transfer roller 61 shown in FIG. 12, and rotates integrally with the secondary transfer roller 61. With such a configuration, when the belt driving roller 41 moves from the contact with the secondary transfer roller 61 to the contact with the first contact member 70, and the second time from the contact with the first contact member 70. It is possible to reduce load fluctuations when moving to contact with the next transfer roller 61.

  Next, the relationship among the secondary transfer roller 61, the intermediate transfer belt 40, and the first contact member 70 will be described.

  FIG. 13 is a diagram illustrating the relationship among the secondary transfer roller 61, the belt driving roller 41, the intermediate transfer belt 40, and the first contact member 70. FIG. 13A is an axial sectional view showing the relationship between the secondary transfer roller 61, the belt driving roller 41, the intermediate transfer belt 40, and the first contact member 70, and FIG. 13B is a diagram of FIG. 13A. FIG. 13A is a cross-sectional view of FIG. 13A. As shown in FIG. 13A, the belt drive roller 41 includes a second contact member 41 c that is supported via a rolling bearing and contacts the support member 70. As shown in FIG. 13B, the second contact member 41c is formed integrally with the belt driving roller 41, and the diameter is twice the thickness of the intermediate transfer belt 40 and the diameter of the belt driving roller 41. It is a thing. As shown in FIG. 13B, the first contact members 70 and 71 are in contact with the second contact member 41c. With such a configuration, it is possible to improve the positioning accuracy of the second contact member 41 c of the belt driving roller 41.

  Next, the Example about the 1st contact member 70 and the 2nd contact member 41c is described. FIGS. 14 and 15 are views showing an embodiment of the first contact member 70 and the second contact member 41c.

  FIG. 14 is a diagram illustrating the first contact member and the second contact member according to the first embodiment. In the first embodiment, the first contact member 70 is formed separately from the shaft 61 a of the secondary transfer roller 61. By forming the first contact member 70 separately from the shaft 61a of the secondary transfer roller 61, it is possible to configure the first contact member 70 with members having different physical properties. Further, the second contact member 41 c is formed separately from the shaft 41 a of the belt driving roller 41. By forming the second contact member 41c separately from the shaft 41a of the belt drive roller 41, it is possible to configure the second contact member 41c with members having different physical properties.

  In the first embodiment, a second contact member 41c that receives the first contact member 70 is provided on a shaft 41a of a belt driving roller 41 as a transfer medium support member. Further, the first contact member 70 is provided in a part of the circumferential direction including a portion corresponding to the concave portion 63 when viewed from the axial direction. The outer diameter of the first contact member 70 is equal to or substantially equal to the outer diameter of the secondary transfer roller 61 when the secondary transfer nip is formed. By setting the outer peripheral diameter of the first contact member 70 to be equal to or substantially equal to the outer peripheral diameter of the secondary transfer roller 61 at the time of forming the secondary transfer nip, the concave portion 63 controls the speed of the outer peripheral portion of the rubber sheet 61c during printing. It becomes possible to make it equal or substantially equal to the speed when passing.

  Moreover, the 1st contact member 70 has the elastic part 70c as an elastic member in the outer periphery. The elastic part 70c is preferably made of the same material as the rubber sheet 61c of the secondary transfer roller 61. By using the same material, the friction coefficients coincide with each other, and the sliding friction can be made substantially constant. The thickness of the elastic portion 70c is preferably the same as or substantially the same as the rubber sheet 61c of the secondary transfer roller 61 when the secondary transfer nip is formed. By making the thicknesses the same or substantially the same, the deformation can be made the same or substantially the same.

  The diameter of the second contact member 41 c is obtained by adding twice the thickness of the intermediate transfer belt 40 and the diameter of the belt driving roller 41. Thus, providing the second contact member 41c is preferable because it is possible to reduce the speed fluctuation of the secondary transfer roller 61 from being transmitted to the belt driving roller 41, and to reduce the disturbance of the transfer image and the latent image.

  FIG. 15 is a diagram illustrating the first contact member and the second contact member according to the second embodiment. The second embodiment includes a contact member receiving portion support member 41d between the shaft 41a of the belt driving roller 41 of the first embodiment and the second contact member 41c. It is preferable that the contact member receiving portion support member 41d be configured to be able to support the axial direction of the belt drive roller 41 as well, because it can reduce backlash in the thrust direction.

  The secondary transfer roller 61 or the belt drive roller 41 preferably has a configuration in which a secondary transfer bias is applied as shown in FIG. FIG. 16 is a diagram illustrating a configuration in which a bias is applied to the secondary transfer roller. In the example illustrated in FIG. 16, the contact C is in contact with the circumferential portion 61 a 1 of the first shaft 61 a of the secondary transfer roller 61 so that a bias is applied from the power source. In addition, it is possible to reliably apply a bias with a simple configuration.

  By transferring with the secondary transfer bias, stable transfer can be performed. Also, transfer by the secondary transfer bias is preferable because contamination of the transfer medium due to melting of the toner in the secondary transfer portion can be suppressed as compared with the case of thermal transfer.

  When the transfer is performed by the secondary transfer bias, it is preferable that the contact member receiving portion support member 41d is formed of an insulating member. The insulating member is provided between the shaft 41a of the belt driving roller 41 and the second contact member 41c. Since the contact member receiving portion support member 41d formed by the above-described structure is provided, leakage is prevented when a bias is applied to the belt drive roller 41, which is preferable.

  10Y, 10M, 10C, 10K ... photosensitive members (image carrier, latent image carrier), 11Y, 11M, 11C, 11K ... corona charger, 12Y, 12M, 12C, 12K ... exposure unit, 13Y ... first photoconductor Squeeze roller, 13Y '... second photoconductor squeeze roller, 18Y ... photoconductor cleaning blade, 20Y, 20M, 20C, 20K ... developing roller (developer carrier), 21Y ... developing roller cleaning blade, 22Y ... compact corona generator , 30Y, 30M, 30C, 30K ... developing device (developing unit), 31Y, 31M, 31C, 31K ... developer container, 32Y, 32M, 32C, 32K ... anilox roller (developer supply member), 33Y ... regulator blade, 34Y ... auger, 40 ... intermediate transfer belt (image carrier belt), 41 ... bell Drive roller (stretching roller), 42 (first) tension roller, 43 ... second tension roller, 44 ... third tension roller, 45 ... intermediate transfer belt cleaning blade, 48 ... third intermediate transfer drum (image carrier) Drum), 50 ... primary transfer portion, 51 ... primary transfer roller, 60 ... secondary transfer portion / transfer portion (transfer portion), 61 ... secondary transfer roller (transfer roller), 61a ... rotating shaft, 61b ... base material, 61c ... Rubber sheet (elastic member) 63 ... recess, 64 ... gripper (transfer material gripping member), 70, 71 ... first contact member, 79 ... extruding claw (transfer material peeling portion), 85 ... secondary transfer roller blade , 90 ... fixing unit, 91 ... heating roller, 92 ... pressure roller, 110 ... bias generator, 210 ... first suction device, 230 ... transfer material transport device, 270 ... first Suction device, S ... transfer material

Claims (5)

An image carrier drum having a rotation axis and carrying an image;
A rotating shaft, a cylindrical substrate having a recess formed in the axial direction of the rotating shaft, a transfer material gripping member disposed in the recess for gripping the transfer material, and an elastic transfer material support for supporting the transfer material. A transfer roller that contacts the image carrier drum and transfers the image carried on the image carrier to the transfer material;
A first contact member disposed in the axial direction of the recess and supported by a rotation shaft of the transfer roller;
A second abutting member supported by a rotating shaft of the image carrier drum via a rolling bearing and abutting on the first abutting member;
An image forming apparatus comprising: An image carrier belt on which an image is carried;
A tension roller having a rotation axis and tensioning the image carrier belt;
A rotating shaft, a cylindrical substrate having a recess formed in the axial direction of the rotating shaft, a transfer material gripping member disposed in the recess for gripping the transfer material, and an elastic transfer material support for supporting the transfer material. A transfer roller that contacts the tension roller via the image carrier belt and transfers the image carried on the image carrier belt to the transfer material;
A first contact member disposed in the axial direction of the recess and supported by a rotation shaft of the transfer roller;
A second abutting member that is supported on a rotating shaft of the stretching roller via a rolling bearing, and that abuts on the first abutting member;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, further comprising a bias applying unit that applies a bias to the transfer roller.   The image forming apparatus according to claim 3, wherein the rolling bearing is an insulating member.   5. The image forming apparatus according to claim 1, wherein the first contact member is provided with an elastic member at a contact portion between the first contact member and the second contact member.

Images