JP2012013735A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus and an image forming method for satisfactorily forming an image by making a transfer roller and an image carrier belt stably contact with each other.SOLUTION: The image forming apparatus comprises: a latent image bearer 10; a developing unit 30 developing the latent image formed on the latent image bearer 10 with a liquid developer containing toner particles and carrier liquid; an image carrier belt 40 on which the image developed on the latent image bearer 10 in the developing unit 30 is transferred; a belt drive roller 41 around which the image carrier belt 40 is wound and which drives the image carrier belt 40; a stretching roller 42 imparting tension to the image carrier belt 40; and a second tension roller 43 imparting tension to the image carrier belt 40. The image forming apparatus is further provided with a transfer roller 61 on which a holding part 64 for holding a transfer material S in a recessed part 63 formed in the peripheral surface of the holding part 64 is disposed, and which contacts to the second tension roller 43 via the image carrier belt 40 and transfers the image carried by the image carrier belt 40 to the transfer material S.

Description

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

  Conventionally, there has been disclosed an image forming apparatus in which a transfer material is held and released by a holding member disposed in a recess of a transfer roller (Patent Document 1). However, the image forming apparatus described in Patent Document 1 switches between when the concave portion of the transfer roller faces the image carrier and when the region other than the concave portion of the transfer roller contacts the image carrier. There is no mention of impact or vibration in position.

  In addition, an image forming apparatus relating to a transfer unit that presses a transfer roller against an image carrier with a pressing member is disclosed (Patent Document 2).

JP-T-2006-513883 JP 2002-156839 A

  When a transfer roller having a recess as shown in Patent Document 1 is pressed against the image carrier by a pressing member as shown in Patent Document 2, when the recess of the transfer roller faces the image carrier, the transfer roller The impact or vibration at the switching position between when the region other than the concave portion abuts against the image carrier is increased, which may affect image formation and deteriorate the image.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and an image forming method for stably forming an image by bringing a transfer roller and an image carrier belt into contact with each other stably.

  The image forming apparatus of the present invention includes a latent image carrier on which a latent image is formed, a developing unit that develops the latent image formed on the latent image carrier with a liquid developer including toner particles and a carrier liquid, An image carrier belt on which the developed image is transferred to the latent image carrier in the developing unit, a belt driving roller that wraps the image carrier belt and drives the image carrier belt, and the belt drive A first tension roller that applies tension to the image carrier belt and a belt that is wound around the first tension roller are wound around the image carrier belt driven by a roller. And a second tension roller for applying tension to the image carrier belt, and a concave portion is formed on the peripheral surface, and a grip portion for gripping the transfer material is disposed in the concave portion. A transfer roller that contacts the second tension roller via the image carrier belt to form a transfer nip and transfers the image carried on the image carrier belt to the transfer material. It is characterized by that.

  The outer diameter of the peripheral surface of the transfer roller excluding the recess is larger than the outer diameter of the second tension roller.

  The image forming apparatus further includes a transfer roller driving unit that rotationally drives the transfer roller.

  Further, an elastic member is provided that presses the second tension roller against the transfer roller via the image carrier belt.

  In addition, a restricting portion that restricts a distance between the rotation center of the transfer roller and the rotation center of the second tension roller is provided.

  The restricting portion includes a cylindrical member disposed coaxially with the transfer roller at an axial end of the second tension roller, and an axial end of the transfer roller. An abutting member that abuts is provided.

  The image forming apparatus further includes a third tension roller that winds the image carrier belt that is wound around the second tension roller.

  Furthermore, in the image forming method of the present invention, a latent image is formed on the latent image carrier, the latent image formed on the latent image carrier is developed, a drive roller, a first tension roller, and a second A transfer roller that transfers an image developed on the latent image carrier onto an image carrier belt wound in the order of a tension roller, has a concave portion on the peripheral surface, and has a gripping portion that grips a transfer material in the concave portion. The transfer material is gripped by the grip portion, and the transfer material gripped by the grip portion is removed from the peripheral surface of the transfer roller excluding the recess and the second tension roller via the image carrier belt. The image transferred to the image carrier belt is transferred to the transfer material at a transfer nip formed in contact with the transfer material.

  According to the present invention, the first tension roller and the second tension roller absorb the shock and vibration that are generated when the transfer roller and the image carrier belt are brought into contact with or separated from each other, and are transmitted to the primary transfer. By preventing this, it is possible to improve image banding and form a good image. In addition, since the first tension roller and the third tension roller apply tension to the image carrier belt on both sides of the second tension roller, it is possible to further absorb impact and vibration.

  In addition, by fixing a large-diameter transfer roller to the frame member and moving and contacting a small-diameter second tension roller having a smaller inertia energy than the transfer roller, the vibration and impact of the transfer roller are suppressed, It is possible to stabilize the gripping and reduce the influence on the image forming unit.

  In addition, by using the transfer roller as an independent rotation drive roller and the second tension roller as a driven roller, it is possible to ensure drive consistency without interfering with each other.

  Further, by providing the cylindrical member and the contact member, the position between the transfer roller and the second tension roller is regulated, and the contact between the gripping member and the image carrier belt can be prevented.

1 is a diagram illustrating main components constituting an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the state which the outer periphery of the secondary transfer roller of 1st Embodiment and the secondary transfer part tension roller are contact | abutting. It is a figure which shows the state which the 1st boundary of the secondary transfer roller of 1st Embodiment and the secondary transfer part stretch roller are contact | abutting. It is a figure which shows the state which the recessed part of the secondary transfer roller of 1st Embodiment and the secondary transfer part stretch roller are facing. It is a figure which shows the state which the 2nd boundary of the secondary transfer roller of 1st Embodiment and the secondary transfer part stretch roller are contact | abutting. It is a figure which shows the state which the support member and contact member of 2nd Embodiment start contact | abutting. It is a figure which shows the state which the recessed part of the secondary transfer roller of 2nd Embodiment and the secondary transfer part stretching roller oppose, and the support member and the contact member are contacting. It is a figure which shows the state from which the support member and contact member of 2nd Embodiment finished contact | abutting, and separated. It is a figure which shows the state which the 1st boundary of the secondary transfer roller of 3rd Embodiment and the secondary transfer part stretch roller are contact | abutting. It is a figure which shows the state which the recessed part of the secondary transfer roller of 3rd Embodiment and the secondary transfer part tension roller are facing. It is a figure which shows the state which the 2nd boundary of the secondary transfer roller of 3rd Embodiment and the secondary transfer part stretch roller are contact | abutting.

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

  FIG. 1 is a diagram showing main components constituting an image forming apparatus according to an embodiment of the present invention. The developing devices 30Y, 30M, 30C, and 30K as the developing units are disposed below the vertical direction of the image forming device with respect to the intermediate transfer belt 40 as the image carrier belt disposed in the center of the image forming device. Configurations such as a secondary transfer unit 60 as a transfer unit and a fixing unit (not shown) are arranged above the image forming apparatus in the vertical direction.

  Around the photoreceptors 10Y, 10M, 10C, and 10K as latent image carriers on which the latent images are formed, corona chargers 11Y, 11M, 11C, and 11K as charging units and LEDs are formed to form an image with toner. Exposure units 12Y, 12M, 12C, 12K and the like as exposure units such as an array are provided. 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 intermediate transfer belt 40 is a belt formed of a seamless elastic member such as rubber. The intermediate transfer belt 40 is stretched around a belt driving roller 41, a tension roller 42, a first tension roller 44, and a second tension roller 43. The belt is driven to rotate by the belt driving roller 41 while contacting the photoreceptors 10Y, 10M, 10C, and 10K by the transfer units 50Y, 50M, 50C, and 50K. In the primary transfer portions 50Y, 50M, 50C, and 50K, the primary transfer rollers 51Y, 51M, 51C, and 51K are disposed opposite to each other with the photoreceptors 10Y, 10M, 10C, and 10K interposed between the intermediate transfer belt 40 and the photoreceptors 10Y, 10M, and 50K. Using the contact position with 10C, 10K as the transfer position, the developed toner images of the respective colors on the photoconductors 10Y, 10M, 10C, 10K are sequentially superimposed and transferred onto the intermediate transfer belt 40 to form a full-color toner image. To do.

  At the portion of the intermediate transfer belt 40 that is stretched by the stretching roller 42, a cleaning unit comprising a transfer belt cleaning blade 49 is brought into contact with and arranged to clean the remaining toner and carrier on the intermediate transfer belt 40. ing.

  The secondary transfer unit 60 includes a secondary transfer roller 61 as a transfer roller. The secondary transfer roller 61 rotates in the direction indicated by the arrow as the second tension roller 43 rotates, and a transfer bias is applied to transfer the toner image on the intermediate transfer belt 40 to the transfer material conveyance path L at the transfer nip. Transfer to a transfer material such as paper, film or cloth. The secondary transfer unit 60 includes a transfer roller cleaning blade 69 that cleans the secondary transfer roller 61.

  A transfer material transport unit (not shown) is arranged downstream of the secondary transfer unit 60 in the transfer material transport path L so as to transport the transfer material to a fixing unit (not shown). A single-color toner image or a full-color toner image transferred onto the transfer material is fused and fixed to a transfer material such as paper.

  The transfer material is supplied to the image forming apparatus by a paper feeding device (not shown). The transfer material 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 is conveyed to the secondary transfer position by the gate rollers 71 and 71 ′ as the transfer material sending member, and a single color toner image or a full color toner image formed on the intermediate transfer belt 40 is obtained. Transfer to transfer material.

  The transfer material that has been secondarily transferred is further transported to the fixing unit by the transfer material transport section as described above. The fixing unit is composed of a heating roller (not shown) and a pressure roller (not shown) urged toward the heating roller with a predetermined pressure, and a transfer material is inserted between the nips on the transfer material. The transferred single-color toner image or full-color toner image is fused and fixed to a transfer material 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 photoconductor 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.

  Next, the configuration of the secondary transfer unit 60 according to the first embodiment will be described. 2 to 5 are enlarged views of the vicinity of the secondary transfer portion 60 of the first embodiment. FIG. 2 is a diagram showing a state in which the outer periphery 61b of the secondary transfer roller 61 is in contact with the second tension roller 43. FIG. 3 is a diagram illustrating the first boundary 61c of the secondary transfer roller 61 and the second tension roller 43. FIG. 4 is a diagram showing a state of contact, FIG. 4 is a diagram showing a state where the concave portion 63 of the secondary transfer roller 61 and the second tension roller 43 are opposed, and FIG. 5 is a second boundary of the secondary transfer roller 61. It is a figure which shows the state which 61d and the 2nd tension roller 43 contact | abut.

  The secondary transfer roller 61 is supported by a first frame 101 as a frame member. Further, the photosensitive members 10Y, 10M, 10C, and 10K, the belt driving roller 41, the second tension roller 43, the first tension roller 44 and the gate rollers 71 and 71 ′, and developing devices 30Y, 30M, 30C, and 30K (not shown). The tension roller 42 is supported by a second frame 102 different from the first frame.

  The secondary transfer roller 61 has a recess 63 in a cylindrical main body. The recess 63 extends in the axial direction of the secondary transfer roller 61. In the recess 63, a gripper 64 as a gripping member and a gripper support portion 61a as a gripping member support portion on which the gripper 64 is seated are disposed. The gripper is configured by the gripper 64 and the gripper support 61a.

  The grippers 64 are arranged along the axial direction of the secondary transfer roller 61, and an arbitrary number of grippers 64 can be provided. Each gripper 64 is provided such that the gripping portion 64b is seated on the gripper support portion 61a by rotating with respect to the rotation shaft 64a. The gripper support portion 61 a is formed by processing the main body at the circumferential end portion on the rear side in the rotation direction of the concave portion 63 of the secondary transfer roller 61. In the present embodiment, the gripping portion 64b and the gripper support portion 61a are configured as flat surfaces, but may be curved surfaces. Note that the gripper support portion 61 a may be configured by a member different from the main body of the secondary transfer roller 61.

  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.

  A second tension roller 43 is disposed at a position opposite to the secondary transfer roller 61 via the intermediate transfer belt 40. The second tension roller 43 is urged toward the secondary transfer roller 61 by a second tension applying member 43a.

  Note that the secondary transfer roller 61 is formed to have a larger diameter than the second tension roller 43. By fixing the large-diameter secondary transfer roller 61 to the first frame 101 as a frame member and moving and bringing the small-diameter second tension roller 43 into contact, the inertial force at the time of contact can be reduced. It becomes possible. The secondary transfer roller 61 is driven to rotate by a drive motor as a transfer roller driving unit (not shown).

  A first tension roller 44 is disposed between the belt driving roller 41 and the second tension roller 43 and inside the intermediate transfer belt 40. The first tension roller 44 presses the intermediate transfer belt 40 from the inside to the outside by the first tension applying member 44a. Therefore, the intermediate transfer belt 40 is always tensioned from the inside to the outside.

  Next, detection of the rotational position of the secondary transfer roller 61 according to the present invention will be described.

  The secondary transfer roller 61 is provided with a detected portion 90 having a detected member 91 that is coaxially supported and rotated integrally with the secondary transfer roller 61, and a slit 92 formed in the detected member 91. .

  A rotation position detector 95 having a sensor support member 96 and a sensor 97 for detecting passage of the slit 92 is provided in a case (not shown) that supports the secondary transfer roller 61. The sensor 97 has a light emitting part and a light receiving part on both sides of the detected member 91, and the light receiving part receives light emitted by the light emitting part when the slit 92 passes between the light emitting part and the light receiving part. By doing so, the rotational position is detected.

  When the sensor 97 detects the slit 92, a control unit (not shown) controls the timing and starts exposure of the exposure unit 12 and conveyance of the transfer material by the gate rollers 71 and 71 '.

  Next, the operation timing of the rotational position detector 95 and the gate rollers 71 and 71 'according to the embodiment of the present invention will be described. In the embodiment according to the present invention, the timing is set so that the sensor 97 detects the slit 92 when the secondary transfer roller 61 and the intermediate transfer belt 40 are in contact with each other without the transfer material S interposed therebetween.

  When the secondary transfer roller 61 rotates and the sensor 97 detects the slit 92, the gate rollers 71 and 71 'are driven after a predetermined time by a signal transmitted from the control unit as shown in FIG. The gate rollers 71 and 71 ′ start rotating from a state in which the leading end S <b> 1 of the transfer material S is sandwiched, and start feeding the transfer material S.

  At this time, the second tension roller 43 is pressed to the secondary transfer roller 61 side by the second tension applying member 43a, but the outer periphery of the secondary transfer roller 61 other than the recess 63 is interposed via the intermediate transfer belt 40. Since the contact is made, the position does not move.

  The sensor 97 detects the slit 92 when the secondary transfer roller 61 and the intermediate transfer belt 40 are in contact with each other without the transfer material S interposed therebetween. As described above, since the sensor 97 is set to detect the slit 92 when the secondary transfer roller 61 and the intermediate transfer belt 40 are in contact with each other without the transfer material S interposed therebetween, the rotational position of the secondary transfer roller 61 is set. Is detected in a stable state, and it is possible to transfer well and form an image.

  Thereafter, the transfer material S is sent out by the gate rollers 71 and 71 ′ as shown in FIG. 3. Here, the secondary transfer roller 61 rotates, and the first boundary 61 c between the outer periphery 61 b of the secondary transfer roller 61 and the recess 63 is a position where the second tension roller 43 abuts.

  The second tension roller 43 is urged by the second tension applying member 43 a, but does not move when it is in contact with the outer periphery 61 b of the secondary transfer roller 61. However, when the second tension roller 43 is opposed to the concave portion 63 of the secondary transfer roller 61, the contact with the outer periphery 61b is lost, so that the second tension roller 43 passes through the first boundary 61c. The second tension applying member 43a tends to move toward the secondary transfer roller side. This moving force may cause an impact on the intermediate transfer belt 40 and generate vibration.

  Since the first tension roller 44 presses the intermediate transfer belt 40 from the inside to the outside by the first tension applying member 44a, the tension is always applied to the intermediate transfer belt 40 from the inside to the outside. Therefore, the impact when the second tension roller 43 passes the first boundary 61c can be reduced by the first tension roller 44, and the first tension roller 44 reduces the vibration of the intermediate transfer belt 40. be able to.

  The opened gripper 64 is preferably set in advance so as not to exceed the virtual outer peripheral diameter line of the outer periphery 61 b of the secondary transfer roller 61 in the recess 63. By setting in this way, it is possible to prevent the gripper 64 and the intermediate transfer belt 40 from contacting each other.

  Next, as shown in FIG. 4, the transfer material S is further fed by the gate rollers 71 and 71 ′, and the leading end S <b> 1 reaches the gripper 64 disposed in the recess 63. The gripper 64 rotates with respect to the rotation shaft 64a, and the gripping portion 64b is seated on the gripper support portion 61a, thereby holding the transfer material S therebetween.

  In this state, the second tension roller 43 faces the concave portion 63 of the secondary transfer roller 61 and does not come into contact with the outer periphery 61b. Therefore, the second tension roller 43 is biased by the second tension adding member 43a. To move to the secondary transfer roller. The first tension roller 44 presses the intermediate transfer belt 40 from the inside to the outside by the first tension applying member 44a. Therefore, tension is always applied to the intermediate transfer belt 40 from the inside to the outside, and the movement of the second tension roller 43 is reduced even when the second tension roller 43 faces the recess 63. Is possible.

  Thereafter, as shown in FIG. 5, the secondary transfer roller 61 further rotates, and the transfer material S is sent out by the gate rollers 71 and 71 ′. Here, the second boundary 61 d between the outer periphery 61 b of the secondary transfer roller 61 and the concave portion 63 is a position where the second tension roller 43 abuts.

  When the second tension roller 43 is opposed to the recess 63 of the secondary transfer roller 61, the second tension roller 43 does not come into contact with the outer periphery 61b. It is said. However, since the first tension roller 44 presses the intermediate transfer belt 40 from the inner side to the outer side by the first tension applying member 44a, the tension is always applied to the intermediate transfer belt 40 from the inner side to the outer side, and the second tension roller 44 The movement of the tension roller 43 is reduced.

  From this state, the second tension roller 43 is given a force that is pressed against the secondary transfer roller 61 against the urging force of the second tension applying member 43a when passing through the second boundary 61d. . This force may cause an impact and generate vibration in the intermediate transfer belt 40.

  Since the first tension roller 44 presses the intermediate transfer belt 40 from the inside to the outside by the first tension applying member 44a, the tension is always applied to the intermediate transfer belt 40 from the inside to the outside. Therefore, the impact when the second tension roller 43 passes through the second boundary 61d can be reduced by the first tension roller 44, and the first tension roller 44 reduces the vibration of the intermediate transfer belt 40. be able to.

  Thereafter, the image is transferred from the intermediate transfer belt 40 when the transfer material S passes through the nip portion between the secondary transfer roller 61 and the intermediate transfer belt 40. At this time, the gate rollers 71 and 71 'may continue to rotate.

  Next, the configuration of the secondary transfer unit 60 according to the second embodiment will be described. 6 to 8 are enlarged views of the vicinity of the secondary transfer unit 60 of the second embodiment. FIG. 6 is a diagram illustrating a state in which the contact member 66 and the cylindrical member 45 start to contact each other, and FIG. 7 illustrates a state in which the concave portion 63 of the secondary transfer roller 61 and the second tension roller 43 are opposed to each other. FIG. 8 is a diagram showing a state in which the member 45 is in contact with each other. FIG. 8 is a diagram showing a state in which the contact member 66 and the cylindrical member 45 are separated from each other after the contact.

  In the second embodiment, the contact member 66 is disposed on the axially outer side of the concave portion 63 of the secondary transfer roller 61, and the cylindrical member 45 that is in contact with the contact member 66 is disposed on the axially outer side of the second tension roller 43. Arrange. The cylindrical member 45 and the abutting member 66 constitute a restricting portion.

  The contact member 66 has an arc portion 66a that is concentric with the outer periphery 61b of the secondary transfer roller 61 and has a slightly larger diameter than the outer periphery 61b. The cylindrical member 45 is coaxial with the second tension roller 43 and has a smaller diameter than the second tension roller 43. In addition, the second tension roller 43 and the second tension roller 43 are biased toward the secondary transfer roller 61 by the second tension applying member 43a. The secondary transfer roller 61 and the second tension roller 43 are in contact with each other to regulate the center-to-center distance between the rotation center of the secondary transfer roller 61 and the rotation center of the second tension roller 43 to a predetermined distance.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  When the secondary transfer roller 61 rotates and the sensor 97 detects the slit 92, the gate rollers 71 and 71 'are driven after a predetermined time. The gate rollers 71 and 71 ′ start rotating from a state in which the leading end S <b> 1 of the transfer material S is sandwiched, and start to convey the transfer material S.

  Thereafter, when the secondary transfer roller 61 further rotates, the contact member 66 and the cylindrical member 45 contact each other as shown in FIG. The contact between the contact member 66 and the cylindrical member 45 is a state in which the outer periphery 61b of the secondary transfer roller 61 is in contact with the outer periphery of the second tension roller 43, specifically, the second tension roller 43. It is set so that the outer periphery starts in a state before facing the recess 63. That is, the arc portion 66 a of the contact member 66 is longer than the recess 63 in the circumferential direction of the secondary transfer roller 61, so that the contact member 66 and the outer periphery 61 b of the secondary transfer roller 61 are viewed from the axial direction. Are set to have overlapping parts.

  The radial length from the arc portion 66a of the contact member 66 to the outer periphery 61b of the secondary transfer roller 61 is the length from the outer periphery of the cylindrical member 45 to the outer periphery of the second tension roller 43, that is, the cylindrical member. It is equal to the difference in diameter between 45 and the second tension roller 43. Thereby, the swinging amount of the second tension roller 43 can be minimized, and the impact when the contact member 66 and the cylindrical member 45 come into contact with each other can be reduced. Even if vibration due to some impact occurs, the first tension roller 44 presses the intermediate transfer belt 40 from the inner side to the outer side by the first tension applying member 44a. As a result, tension is applied from the outside to the outside, and vibration can be reduced.

  Next, as shown in FIG. 7, the transfer material S is further conveyed by the gate rollers 71 and 71 ′, and the leading end S <b> 1 reaches the gripper 64 disposed in the recess 63. The gripper 64 rotates with respect to the rotation shaft 64a, and the gripping portion 64b is seated on the gripper support portion 61a, thereby holding the transfer material S therebetween.

  In this state, the second tension roller 43 is opposed to the concave portion 63 of the secondary transfer roller 61 and is not in contact with the outer periphery 61b. However, since the contact member 66 and the cylindrical member 45 are in contact with each other, the second tension roller 43 cannot move to the secondary transfer roller 61 side. Therefore, contact between the gripper 64 and the intermediate transfer belt 40 can be prevented.

  Thereafter, when the secondary transfer roller 61 further rotates, the contact member 66 and the cylindrical member 45 are separated as shown in FIG. The contact member 66 and the cylindrical member 45 are separated from each other when the outer periphery 61b of the secondary transfer roller 61 is in contact with the outer periphery of the second tension roller 43, specifically, the outer periphery of the second tension roller 43. Is set to start in a state after facing the recess 63. That is, the arc portion 66 a of the contact member 66 is longer than the recess 63 in the circumferential direction of the secondary transfer roller 61, so that the contact member 66 and the outer periphery 61 b of the secondary transfer roller 61 are viewed from the axial direction. Are set to have overlapping parts.

  Further, the impact when the abutting member 66 and the cylindrical member 45 are separated can be reduced in the same manner as when abutting.

  Next, the configuration of the secondary transfer unit 60 and the like according to the third embodiment will be described. 9 to 11 are enlarged views of the vicinity of the secondary transfer unit 60 of the third embodiment. FIG. 9 is a diagram illustrating a state where the first boundary 61c of the secondary transfer roller 61 and the second tension roller 43 are in contact with each other. FIG. 10 illustrates that the concave portion 63 of the secondary transfer roller 61 and the second tension roller 43 are in contact with each other. FIG. 11 is a diagram showing a state in which the second tension roller 43 is in contact with the second boundary 61 d of the secondary transfer roller 61.

  In the third embodiment, a first tension roller 44 is disposed between the second tension roller 43 and the belt drive roller 41, and the second tension roller 43 and the tension roller 42 shown in FIG. A third tension roller 46 is disposed between them.

  Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  As shown in FIG. 9, the first tension roller 44 presses the intermediate transfer belt 40 from the inner side to the outer side by the first tension applying member 44a, and the third tension roller 46 is pressed by the third tension adding member 46a. Since the belt 40 is pressed from the inside to the outside, tension is always applied to the intermediate transfer belt 40 from the inside to the outside. Therefore, the impact when the second tension roller 43 passes the first boundary 61c can be reduced by the first tension roller 44 and the third tension roller 46, and the first tension roller 44 and the third tension roller 44 can be reduced. The tension roller 46 can reduce the vibration of the intermediate transfer belt 40.

  Thereafter, as shown in FIG. 10, the secondary transfer roller 61 further rotates, and the transfer material S is conveyed by the gate rollers 71 and 71 '. Then, the second tension roller 43 is in a state of facing the concave portion 63 of the secondary transfer roller 61.

  Since the second tension roller 43 is not in contact with the outer periphery 61b in a state of facing the concave portion 63 of the secondary transfer roller 61, the secondary transfer roller 43 is biased by the urging force of the second tension adding member 43a as an elastic member. Trying to move to the side. However, the first tension roller 44 presses the intermediate transfer belt 40 from the inside to the outside by the first tension applying member 44a, and the third tension roller 46 pushes the intermediate transfer belt 40 from the inside to the outside by the third tension adding member 46a. Therefore, the intermediate transfer belt 40 is always tensioned from the inside to the outside, and the movement of the second tension roller 43 is reduced.

  Thereafter, as shown in FIG. 11, the secondary transfer roller 61 further rotates, and the transfer material S is conveyed by the gate rollers 71 and 71 '. Here, the second boundary 61 d between the outer periphery 61 b of the secondary transfer roller 61 and the concave portion 63 is a position where the second tension roller 43 abuts.

  The second tension roller 43 is given a force that is pressed against the secondary transfer roller 61 against the urging force of the second tension application member 43a when passing through the second boundary 61d. This force may cause an impact and generate vibration in the intermediate transfer belt 40.

  The first tension roller 44 and the third tension roller 46 press the intermediate transfer belt 40 from the inside to the outside by the first tension addition member 44a and the third tension addition member 46a. , Tension is always applied from the inside to the outside. Therefore, the impact when the second tension roller 43 passes through the first boundary 61d can be mitigated by the first tension roller 44 and the third tension roller 46, and the first tension roller 44 and the third tension roller 44 can be reduced. The tension roller 46 can reduce the vibration of the intermediate transfer belt 40.

  In addition, you may form embodiment which combined 2nd Embodiment and 3rd Embodiment.

  10Y, 10M, 10C, 10K ... photosensitive body (latent image carrier), 11Y, 11M, 11C, 11K ... corona charger, 12Y, 12M, 12C, 12K ... exposure unit, 13Y ... first photoconductor squeeze roller, 13Y '... second photosensitive member squeeze roller, 18Y ... photosensitive member 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 ... regulating blade, 34Y ... auger 40 ... Intermediate transfer belt (image carrier belt), 41 ... Belt drive low -42 ... tension roller, 43 ... second tension roller, 43a ... second tension applying member (elastic member), 44 ... first tension roller, 45 ... cylindrical member (regulator), 46 ... third Tension roller 49 ... Intermediate transfer belt cleaning blade 50 ... Primary transfer portion 51 ... Primary transfer roller 60 ... Secondary transfer portion (transfer portion) 61 ... Secondary transfer roller (transfer roller) 63 ... Recess portion 64 ... Gripper (gripping member), 66 ... Contact member (regulating part), 71, 71 '... Gate roller (feeding part), 90 ... Detected part, 91 ... Detected member, 92 ... Slit, 95 ... Detecting part, 96 ... sensor support part, 97 ... sensor, 101 ... first frame, 102 ... second frame, S ... transfer material

Claims (8)

A latent image carrier on which a latent image is formed;
A developing section for developing the latent image formed on the latent image carrier with a liquid developer containing toner particles and a carrier liquid;
An image carrier belt to which an image developed on the latent image carrier in the developing unit is transferred;
A belt drive roller for winding the image carrier belt and driving the image carrier belt;
A first tension roller that wraps the image carrier belt driven by the belt driving roller and applies tension to the image carrier belt;
A second tension roller that wraps the image carrier belt wound around the first tension roller and applies tension to the image carrier belt;
A concave portion is formed on the peripheral surface, a grip portion for gripping the transfer material is disposed in the concave portion, and a transfer nip is formed by contacting the second tension roller via the image carrier belt, A transfer roller for transferring the image carried on an image carrier belt to the transfer material;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein an outer diameter of a peripheral surface excluding the concave portion of the transfer roller is larger than an outer diameter of the second tension roller.   The image forming apparatus according to claim 1, further comprising a transfer roller driving unit that rotationally drives the transfer roller.   The image forming apparatus according to claim 1, further comprising an elastic member that presses the second tension roller against the transfer roller via the image carrier belt.   5. The image forming apparatus according to claim 1, further comprising a regulating portion that regulates a distance between a rotation center of the transfer roller and a rotation center of the second tension roller.   The restricting portion is disposed at the axial end portion of the second tension roller and coaxially with the transfer roller, and is disposed at the axial end portion of the transfer roller and contacts the cylindrical member. The image forming apparatus according to claim 5, further comprising a contact member.   The image forming apparatus according to claim 1, further comprising a third tension roller that winds the image carrier belt wound around the second tension roller. Forming a latent image on the latent image carrier,
Developing the latent image formed on the latent image carrier,
The image developed on the latent image carrier is transferred to an image carrier belt wound in the order of a driving roller, a first tension roller, and a second tension roller,
Holding the transfer material with the gripping portion of the transfer roller having a concave portion on the peripheral surface and having a gripping portion for gripping the transfer material in the concave portion,
The transfer material gripped by the gripping portion is transferred to the peripheral surface of the transfer roller excluding the concave portion and the transfer nip formed in contact with the second tension roller via the image carrier belt. An image forming method, wherein the image transferred to a carrier belt is transferred to the transfer material.

Images