JP2011043725A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent misalignment of an image due to velocity fluctuations of a transfer belt that occur by impacts upon passing an entrance of a recessed part provided in a transfer roller. <P>SOLUTION: The image forming apparatus includes: an image carrier 10 carrying an image; a transfer belt 40 onto which an image carried by the image carrier 10 is transferred; and a transfer roller 61 which has a recessed part 605 on the circumference face in the axial direction and includes a transfer material gripping part 610 arranged in the recessed part 605, for gripping a transfer material, and which transfers an image preliminarily transferred onto the transfer belt 40 onto a transfer material at a transfer nip formed by the contact with the transfer belt 40. The circumference length of a virtual circumference face of the recessed part 605 corresponding to the circumference face of the transfer roller 61 is larger than the width of the transfer nip in the conveyance direction of the transfer material and is larger than the distance of the transfer belt 40 between the transfer position of the transfer belt 40 where an image on the image carrier 10 is transferred and the position of the transfer nip. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention develops a latent image formed on a photosensitive member by developing with a liquid developer composed of toner and carrier, further transfers the developer thereby to a medium such as recording paper, and further on the transferred medium. The present invention relates to an image forming apparatus and an image forming method for forming an image by fusing and fixing a toner image.

  Various wet image forming apparatuses that develop a latent image using a high-viscosity liquid developer in which a toner composed of a solid component is dispersed in a liquid solvent and visualize the electrostatic latent image have been proposed. The developer used in this wet image forming apparatus suspends solids (toner particles) in a highly viscous organic solvent (carrier liquid) having electrical insulation properties such as silicon oil, mineral oil, and edible oil. The toner particles are extremely fine with a particle diameter of around 1 μm. By using such fine toner particles, the wet image forming apparatus can achieve higher image quality than a dry image forming apparatus using powder toner particles having a particle diameter of about 7 μm.

  As an image forming apparatus using such a liquid developer, for example, in Patent Document 1, an electrostatic latent image is formed on a drum 10 having a photoconductive surface 12 by an image device 16 such as a laser scanner. Subsequently, an image device is described in which the electrostatic latent image is developed with a liquid toner containing charged toner particles and a carrier liquid, and the developed image is printed on a substrate 44.

  In this image apparatus, the base material 44 is passed through a transfer portion formed by the intermediate transfer member 40 and the stamp roller 42, and the developed image is transferred onto the base material 44 on the intermediate transfer member 40. In particular, a gripper 76 is mounted on the stamping roller 42, grips the front end portion of the substrate 44 sent to the stamping roller 42, and transfers the substrate 44 after the image on the intermediate transfer member 40 is transferred. The image to be transferred to the substrate 44 is positioned by releasing the.

Special Table 2000-508280

  As described above, in the image device described in Patent Document 1, the base material 44 is positioned by the gripper 76 mounted on the stamping roller 42. FIG. 1 and FIG. As can be seen from the above, this gripper 76 is provided on the surface layer of the stamping roller 42 and has a small and simple mechanism so as not to hinder the rotation of the intermediate transfer member 40 and the pressing roller 42. I can only do it.

  With such a small gripper 76, it is not possible to secure a sufficient grip allowance for gripping the base material 44 and to grip the base material 44 with sufficient force. In such a case, there is a high possibility that the base material 44 will drop off from the gripper 76 during the transfer, which not only causes printing failure but also contaminates the inside of the device due to the dropped base material 44 remaining in the device. This may cause malfunctions. Further, the gripper 76 having such a simple mechanism cannot accurately grip the front end portion of the base material 44, which causes printing misalignment.

In order to solve such a problem, the inside of the concave portion is provided along the axis of the transfer roller, and the transfer material gripping portion is provided in the concave portion, so that the transfer material gripping portion can be increased in size and complicated. A mechanism can also be adopted, and the transfer material can be firmly held at an accurate position.

  However, when such a transfer roller having a relatively large concave portion on the surface is employed, a new problem may occur. When transferring to the transfer material with the transfer roller and transfer belt, the vibration generated by the impact when the recess provided on the transfer roller separates from the transfer belt becomes the speed fluctuation of the transfer belt, and as a result, from the image carrier Deviation occurs in the image during the primary transfer to the transfer belt. In particular, in a black developer containing carbon black or iron oxide as a component, such a shift in the transferred image becomes visually noticeable in a halftone or an outline portion of the image, which causes deterioration of the image. .

  In order to solve such a problem, the image forming apparatus of the present invention has an image carrier that carries an image, a transfer belt to which the image carried on the image carrier is transferred, and a recess in the axial direction of the peripheral surface. A transfer material gripping portion for gripping the transfer material in the recess, and an image transferred to the transfer belt is transferred to the transfer material at a transfer nip formed by contact with the transfer belt. A peripheral length of the virtual peripheral surface of the recess corresponding to the peripheral surface of the transfer roller is larger than a width of the transfer nip portion in the transfer material conveyance direction, It is characterized by being larger than the distance of the transfer belt between the transfer position of the transfer belt to which the image is transferred and the position of the transfer nip portion.

  As described above, when the circumferential length of the virtual peripheral surface of the recess is larger than the width of the transfer nip portion in the transfer material conveyance direction, that is, the transfer belt that has been rotating in contact with the transfer roller is provided on the transfer roller. In a configuration in which the image bearing member is once separated from the transfer roller when facing the recessed portion, the distance of the transfer belt between the transfer position of the transfer belt to which the image on the image carrier is transferred and the position of the transfer nip portion is determined. This also makes it possible to transfer the image from the image carrier to the transfer belt while avoiding the speed fluctuation of the transfer belt that occurs when the transfer roller moves away from the transfer belt. A shift can be prevented.

  Furthermore, the image forming apparatus of the present invention has a second image carrier that carries an image, and the image carried on the second image carrier is transferred to the transfer belt and the second image carrier. The image carried on the image carrier is transferred to the transfer belt on which the image carried on the image carrier is transferred.

  In this way, the present invention is also applied to a color image forming apparatus having a plurality of image carriers, and it is possible to prevent image shift due to speed fluctuation of the transfer belt.

  Further, in the image forming apparatus of the present invention, the image carried on the image carrier is an image developed with a liquid developer having a toner and a carrier liquid, and the toner contains carbon black or iron oxide. To do.

  As described above, by adopting the configuration of the present invention for an image carrier using a black developer containing carbon black or iron oxide as a component, it is possible to develop an image with respect to a developer whose image shift is visually noticeable. It is possible to suppress the deviation and improve the image quality.

  Further, the image forming apparatus of the present invention includes a speed control unit that controls the moving speed of the transfer belt, and the speed control unit that controls the moving speed of the transfer belt, and then the image carried on the image carrier. And a controller for starting transfer to the transfer belt.

By providing a speed control unit that controls the speed of the transfer belt in this way, it is possible to control the amount of fluctuation in the speed fluctuation of the transfer belt that occurs when the transfer roller is separated from the transfer belt and to stabilize it at an early stage. Therefore, it is possible to prevent the image transferred from the image carrier to the transfer belt from being displaced.

  Furthermore, the image forming apparatus of the present invention includes a contact member disposed in the axial direction of the concave portion of the transfer roller, a tension roller that contacts the transfer roller via the transfer belt, and a tension roller And a support member disposed in the axial direction and in contact with the contact member.

  When the support member provided on the tension roller for stretching the transfer belt and the contact member provided at the position corresponding to the opening of the transfer roller are provided, the recess is separated from the transfer. In this case, the support member and the contact member are in contact with each other, so that vibration at the time of separation can be suppressed.

  Also, the image forming method of the present invention transfers an image carried on an image carrier onto a transfer belt, and applies the image transferred onto the transfer belt to the transfer belt and a transfer roller having a concave portion on a peripheral surface. The transfer roller is moved to the transfer nip formed by the contact, and is disposed in the recess by the transfer roller having a circumference of a virtual peripheral surface corresponding to the peripheral surface of the transfer roller of the recess different from the moving distance of the image. The image is transferred to a transfer material held by the transferred transfer material holding portion.

  In this way, the transfer roller is made different by making the circumference of the virtual peripheral surface of the recess provided in the transfer roller different from the distance that the image transferred to the transfer belt by the image carrier moves to the transfer nip. It is possible to transfer the image from the image carrier to the transfer belt while avoiding the speed fluctuation of the transfer belt that occurs when separating from the transfer belt, and it is possible to prevent the image from being shifted due to the speed fluctuation of the transfer belt. .

1 is a diagram illustrating main components constituting an image forming apparatus according to an embodiment of the present invention. It is a perspective view of a secondary transfer roller used in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an operation of a transfer material gripping portion of a secondary transfer roller used in an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a diagram illustrating an operation of a transfer material transport unit used in the image forming apparatus according to the embodiment of the present invention. FIG. 2 is a diagram illustrating an outline of a control block in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an operation of a secondary transfer unit in the image forming apparatus according to the embodiment of the present invention. FIG. 6 is a diagram illustrating an operation of a secondary transfer unit in the image forming apparatus according to the embodiment of the present invention. FIG. 4 is a diagram illustrating details of a secondary transfer roller in the image forming apparatus according to the embodiment of the present invention. It is a figure which shows the mode of separation of the secondary transfer roller and transfer belt which concern on embodiment of this invention. FIG. 6 is a diagram illustrating a state of speed fluctuation of the transfer belt when the secondary transfer roller is separated from the transfer belt. It is a figure explaining the various distances in the image forming apparatus which concerns on embodiment of this invention. FIG. 3 is a diagram illustrating an arrangement of various configurations in an image forming apparatus according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a state of speed fluctuation of the transfer belt when the secondary transfer roller is separated from the transfer belt. FIG. 6 is a diagram illustrating a state of speed fluctuation of the transfer belt when the secondary transfer roller is separated from the transfer belt.

  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 embodiment of the present invention. The developing devices 30Y, 30M, 30C, and 30K are arranged in the lower part of the image forming apparatus with respect to the image forming units of the respective colors arranged in the central part of the image forming apparatus, and the transfer belt 40, the secondary transfer unit (secondary transfer unit The configuration of the transfer unit 60, the fixing unit 90, and the like is disposed in the upper part of the image forming apparatus. In particular, since the fixing unit 90 is laid out above the transfer belt 40, the installation area of the entire image forming apparatus can be suppressed. As described above, in the present exemplary embodiment, a transfer material such as paper that has undergone secondary transfer by the secondary transfer unit 60 is transported to the fixing unit 90 while being sucked by the transfer material transport device 230 and the suction devices 210 and 270. Such a layout can be realized because of the configuration.

  Developing devices (“developing units” in the present invention) 30Y, 30M, 30C, and 30K are photosensitive members 10Y, 10M, 10C, and 10K, and corona chargers 11Y, 11M, 11C, and 11K to form an image using toner. And exposure units 12Y, 12M, 12C, 12K, etc., such as LED arrays. The photoreceptors 10Y, 10M, 10C, and 10K are uniformly charged by the corona chargers 11Y, 11M, 11C, and 11K, and input by the exposure units 12Y, 12M, 12C, and 12K (the “exposure unit” in the present invention). Exposure is performed based on the image signal thus formed, and latent images are formed on the charged photoconductors 10Y, 10M, 10C, and 10K.

  The developing devices 30Y, 30M, 30C, and 30K generally include liquid developers of respective colors including the developing rollers 20Y, 20M, 20C, and 20K, yellow (Y), magenta (M), cyan (C), and black (K). Developer containers (reservoirs) 31Y, 31M, 31C, 31K to be stored, and application rollers for applying liquid developers of these colors from the developer containers 31Y, 31M, 31C, 31K to the developing rollers 20Y, 20M, 20C, 20K. The anilox rollers 32Y, 32M, 32C, 32K and the like are provided, and the latent images formed on the photoreceptors (“image carrier” in the present invention) 10Y, 10M, 10C, 10K are developed with liquid developers of respective colors.

  The transfer belt 40 is an endless belt, is stretched around a drive roller 41 and a tension roller 42, and is in contact with the photoreceptors 10Y, 10M, 10C, and 10K by the primary transfer units 50Y, 50M, 50C, and 50K. 41 is rotationally driven. The primary transfer portions 50Y, 50M, 50C, and 50K are arranged such that the primary transfer backup rollers 51Y, 51M, 51C, and 51K face each other with the transfer belt 40 sandwiched between the photoconductors 10Y, 10M, 10C, and 10K. The developed toner image of each color on the photoreceptors 10Y, 10M, 10C, and 10K is sequentially transferred onto the transfer belt 40 with the contact position with 10M, 10C, and 10K as the transfer position, and a full-color toner image is transferred. Form.

  In the secondary transfer unit 60, a secondary transfer roller 61 is disposed opposite to the belt driving roller 41 with the transfer belt 40 interposed therebetween, and a cleaning device including a secondary transfer roller cleaning blade 62 is disposed. Then, at a transfer position where the secondary transfer roller 61 is disposed, transfer of a single-color toner image or a full-color toner image formed on the transfer belt 40 through a transfer material transport path L is performed. Transfer to material.

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

  The tension roller 42 stretches the transfer belt 40 together with the belt drive roller 41 and the like, and a cleaning device including a transfer belt cleaning blade 49 is disposed in contact with the tension roller 42 of the transfer belt 40 where the tension belt 42 is stretched. The remaining toner and carrier on the transfer belt 40 are cleaned. The driving force for driving the transfer belt 40 can be given to the tension roller 42 and the belt driving roller 41 can be used as a simple belt stretching roller.

  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 101, 101 ′ and the transfer material guide 102, and a single color toner development image or a full color toner development image formed on the transfer belt 40 is obtained. Transfer to transfer material. As described above, the transfer material subjected to the secondary transfer is further conveyed to the fixing unit 90 by the transfer material conveying means centering on the transfer material conveying device 230. The fixing unit 90 includes a heating roller 91 and a pressure roller 92 urged to the heating roller 91 side with a predetermined pressure. A transfer material is inserted between the nips, and the transfer material is placed 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 image forming unit and the developing device will be described. Since the configurations of the image forming unit and the developing device for each color are the same, the following description will be made based on the yellow (Y) image forming unit and the developing device.

  The image forming unit includes a corona charger 11Y, an exposure unit 12Y (“exposure unit” in the present invention), a developing roller 20Y of the developing device 30Y, and a first photosensitive member squeeze roller 13Y along the rotation direction of the outer periphery of the photosensitive member 10Y. The second-stage photosensitive member squeeze roller 13Y ′, the primary transfer unit 50Y, the neutralization unit (not shown), and the photosensitive member cleaning blade 18Y are arranged upstream of the configuration arranged in the subsequent stage. Defined.

  On the downstream side of the primary transfer portion 50Y, the photoconductor cleaning blade 18Y that is in contact with the photoconductor 10Y cleans the liquid developer rich in carrier components on the photoconductor 10Y.

  A cleaning blade 21Y, an anilox roller 32Y, and a compaction corona generator 22Y are arranged on the outer periphery of the developing roller 20Y in the developing device 30Y. A regulating blade 33Y that adjusts the amount of liquid developer supplied to the developing roller 20Y is in contact with the anilox roller 32Y. An auger 34Y is accommodated in the liquid developer container 31Y. Further, a primary transfer backup roller 51Y of the primary transfer portion is disposed at a position facing the photoconductor 10Y so as to sandwich the transfer belt 40.

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

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 includes a photoconductor 10Y from the corona charger 11Y.
On the downstream side in the rotation direction, light is irradiated onto the photoconductor 10Y charged by the corona charger 11Y to form a latent image on the photoconductor 10Y. Note that, from the beginning to the end of the image forming process, the configuration of the rollers and the like arranged in the preceding stage is defined to be upstream from the configuration of the rollers and the like arranged in the subsequent stage.

  The developing device 30Y includes a compaction corona generator 22Y that performs a compaction action, 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%.

  Further, 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, an auger 34Y for feeding the liquid developer to the anilox roller 32Y while stirring and conveying the liquid developer, a compaction corona generator 22Y for bringing the liquid developer carried on the developing roller 20Y into a compacted state, and a developing roller 20Y A developing roller cleaning blade 21Y for cleaning is provided.

  The liquid developer contained in the developer container 31Y is a low-concentration (about 1 to 2 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. Viscoelasticity at a shear rate of 1000 (1 / s) at 25 ° C. with a high viscosity (HAAKE RheoStress RS600) added with a dispersant and having a toner solid content concentration of about 20%. 30 to 300 mPa · s Liquid developer.

  The anilox roller 32Y functions as an application roller that supplies and applies a liquid developer to the developing roller 20Y. The anilox roller 32Y is a cylindrical member, and is a roller having a concave and convex surface formed by grooves engraved in a fine and uniform spiral shape on the surface so as to easily carry a developer on the surface. The anilox roller 32Y supplies the liquid developer from the developer container 31Y to the developing roller 20Y. During the operation of the apparatus, as shown in FIG. 1, the auger 34Y rotates counterclockwise to supply the liquid developer to the anilox roller 32Y, and the anilox roller 32Y rotates counterclockwise to supply liquid to the developing roller 20Y. Apply developer.

The regulating blade 33Y is a metal blade having a thickness of about 200 μm, is placed on the surface of the anilox roller 32Y, regulates the film thickness and amount of the liquid developer carried and conveyed by the anilox roller 32Y, and the developing roller 20Y. The amount of the liquid developer supplied to is adjusted.

  The developing roller cleaning blade 21Y is made of rubber or the like that contacts the surface of the developing roller 20Y. The developing roller 20Y is disposed downstream of the developing nip portion where the developing roller 20Y contacts the photoreceptor 10Y in the rotation direction of the developing roller 20Y. The liquid developer remaining on the roller 20Y is scraped off and removed.

  The compaction corona generator 22Y is an electric field applying means for increasing the charging bias on the surface of the developing roller 20Y. An electric field is applied from the compaction corona generator 22Y to the developing roller 20Y at the compaction site by the compaction corona generator 22Y. The The electric field applying means for compaction may use a compaction roller or the like instead of the corona discharge of the corona discharger shown in FIG.

  The developer carried on the developing roller 20Y and compacted is developed corresponding to the latent image on the photoconductor 10Y by applying a predetermined electric field at the developing nip portion where the developing roller 20Y contacts the photoconductor 10Y.

  The developer remaining after development is scraped off and removed by the developing roller cleaning blade 21Y and dropped into the collecting section in the developer container 31Y to be reused. The carrier and toner that are reused in this way are not in a mixed color state.

  The photosensitive member squeeze device disposed upstream of the primary transfer is disposed downstream of the developing roller 20Y so as to face the photosensitive member 10Y, and collects excess carrier of the toner image developed on the photosensitive member 10Y. is there. This photoconductor squeeze device is composed of a first photoconductor squeeze roller 13Y and a second photoconductor squeeze roller 13Y ′ made of an elastic roller member that slides in contact with the photoconductor 10Y, and is developed on the photoconductor 10Y. It has a function of collecting excess carrier and originally unnecessary fog toner from the toner image and increasing the toner particle ratio in the visible image (toner image). A predetermined bias voltage is applied to the photoconductor squeeze rollers 13Y and 13Y '.

  The surface of the photoreceptor 10Y that has passed through the squeeze device including the first photoreceptor squeeze roller 13Y and the second photoreceptor squeeze roller 13Y 'enters the primary transfer unit 50Y. In the primary transfer portion 50Y, the developer image developed on the photoreceptor 10Y is transferred to the transfer belt 40 by the primary transfer backup roller 51Y. In the primary transfer portion, the toner image on the photoreceptor 10Y is transferred to the transfer belt 40 side by the action of the transfer bias applied to the primary transfer backup roller 51Y. Here, the photoconductor 10Y and the transfer belt 40 are configured to move at a constant speed, and the driving load of rotation and movement is reduced, and the disturbance effect on the visible toner image of the photoconductor 10Y is suppressed.

  In the developing devices 30M, 30C, and 30K, magenta (M), cyan (C), and black (K) toners are respectively formed on the photoreceptors 10M, 10C, and 10K by a process similar to the developing process of the developing device 30Y. Each image is formed. The transfer belt 40 passes through the nip of the primary transfer portion 50 for each color of yellow (Y), magenta (M), cyan (C), and black (K), and a developer (development image) on the photoreceptor of each color. Are transferred, color-superposed, and enter the nip portion of the secondary transfer unit 60.

  The transfer belt 40 that has passed through the secondary transfer unit 60 circulates again to receive the transfer image at the primary transfer unit 50, but on the upstream side where the primary transfer unit 50 is executed, the transfer belt 40 is a transfer belt cleaning blade. 49 or the like is performed for cleaning.

  The transfer belt 40 has a three-layer structure in which an elastic intermediate layer of polyurethane is provided on a polyimide base layer, and a PFA surface layer is provided thereon. The transfer belt 40 is stretched by a belt driving roller 41 and a tension roller 42, and is used so that a toner image is transferred on the PFA surface layer side.

  Next, the secondary transfer roller 61 (“transfer roller” in the present invention) used in the image forming apparatus according to the present embodiment will be described in more detail. FIG. 2 is a perspective view of a secondary transfer roller used in the image forming apparatus according to the embodiment of the present invention, and FIG. 3 is a drawing of a transfer material of the secondary transfer roller used in the image forming apparatus according to the embodiment of the present invention. It is a figure which shows operation | movement of a part. 2 and 3, reference numeral 601 denotes a roller base material, 602 denotes a roller shaft portion, 605 denotes a concave portion, 607 denotes an elastic member, 610 denotes a transfer material gripping portion, 611 denotes a gripping member, 612 denotes a gripping member receiving portion, and 640 denotes a transfer. A material peeling member 650 indicates a contact member.

  Roller shaft portions 602 are provided at both ends of the roller base material 601 of the secondary transfer roller 61, and are attached to the apparatus main body side so as to be rotatable about the roller shaft portions 602. Further, the roller base material 601 is provided with a concave portion 605 extending in the axial direction, and a transfer material gripping portion 610 is provided in the concave portion 605. The transfer material gripping part 610 is a mechanism for gripping or releasing the transfer material.

  The roller base 601 other than the recess 605 is provided with an elastic member 607 that supports the transfer material. The elastic member 607 is fixed to the roller base material 601 by a fixing portion provided in the recess 605. The elastic member 607 is composed of a semiconductive elastic rubber layer having an electrical resistance component, and passes through a secondary transfer nip in the secondary transfer unit 60 in a state where a transfer material is wound around the elastic member 607. Sometimes, the toner image is transferred from the transfer belt 40 to the transfer material.

  By winding the elastic member 607 around the transfer roller 40 in this way, it is possible to secure a wide width of the secondary transfer nip formed by the transfer roller 61 and the transfer belt 40 and to increase transfer efficiency. Further, since the fixing portion for fixing the elastic member 607 is disposed in the concave portion 605 of the transfer roller 61, there is no need to fix the elastic member 607 on the surface of the transfer roller 61, and the surface of the transfer roller 61 is uniform. It is possible to form a flexible elastic layer and improve the quality during transfer.

  The transfer material gripping portion 610 is roughly composed of a pair of gripping members 611 and gripping member receiving portions 612 that are discretely provided in the roller axial direction, and a plurality of transfers that are appropriately arranged between the pair in the roller axial direction. The material peeling member 640 is comprised. All the gripping members 611 are configured to be movable, and operate to sandwich the transfer material with the gripping member receiving portion 612 to grip the transfer material or between the gripping member receiving portion 612. The transfer material can be released by operating at intervals. Further, all the transfer material peeling members 640 operate so as to push out the transfer material held by the holding member 611 and the holding member receiving portion 612 in a direction away from the secondary transfer roller 61 side.

  Two contact members 650 are provided at both ends of the roller shaft portion 602 of the secondary transfer roller 61. The contact member 650 has a structure in which a concave portion 605 is provided in the secondary transfer roller 61 when viewed from the roller axial direction and has a contact surface in a region corresponding to the open region. The position between the secondary transfer roller 61 and the belt drive roller 41 is regulated by the surface coming into contact with a support member described later.

  The operation of the transfer material grip 610 will be described in more detail with reference to FIG. FIG. 3 is a diagram of each configuration of the transfer material gripping portion 610 schematically shown from the axial direction. 3A, FIG. 3B, FIG. 3C, and FIG. 3D show the states of the transfer material gripping portion 610 in the secondary transfer roller 61 of FIG. 6 schematically shows an operation state that the transfer material gripping part 610 takes when the transfer material gripping part 610 of the secondary transfer roller 61 comes to the position marked as C or D.

  FIG. 3A shows a state where the secondary transfer roller 61 is rotating without gripping the transfer material by the transfer material gripping portion 610. At this time, the gripping member 611 and the transfer material peeling member 640 are configured to fit within the outermost periphery when the secondary transfer roller 61 is viewed as a cylinder. This shows a state when the transfer material gripping portion 610 exists in the range of A in FIG. 1 during the rotation process of the secondary transfer roller 61.

3B, the gripping member 611 moves in the direction (a) to form a predetermined space with the gripping member receiving portion 612, and the transfer material S entering the space is gripped by the gripping member 611 and the gripping member 611. It is a figure which shows the state which is preparing to clamp with the member receiving part 612. FIG. In the rotation process of the secondary transfer roller 61, the transfer material gripping portion 610 comes to the position B in FIG. 1 and enters along the transfer material guide 102 along with the rotation of the gate rollers 101 and 101 ′. The state which is preparing the holding | grip of a transfer material is shown.

  FIG. 3C shows a state in which the transfer material S that has entered the space is sandwiched between the gripping member receiving portion 612 as the gripping member 611 moves in the (a ′) direction. At this time, the transfer material S gripped at one end by the transfer material gripping portion 610 is wound around the roller base material 601 of the secondary transfer roller 61 as the secondary transfer roller 61 rotates. As described above, since the transfer material S is held and fixed by the transfer material holding portion 610 before the transfer material enters the secondary transfer nip, the transfer material S to which the toner image is transferred can be positioned accurately. . In the rotation process of the secondary transfer roller 61, when the transfer material gripping portion 610 is located in the range C in FIG. 1, the state shown in FIG. 3C is maintained.

  3D, the gripping member 611 moves in the direction (a) to form a predetermined space with the gripping member receiving portion 612 to release the transfer material S, and the transfer material peeling member 640 has (b). It shows a state where the transfer material S is pushed in the direction away from the secondary transfer roller 61 by moving in the direction. In this operation state, in the rotation process of the secondary transfer roller 61, the transfer material gripping portion 610 comes to the position D in FIG. 1 and the transfer material S on which the toner image is transferred through the secondary transfer nip is moved to the next. This is for delivery to the transfer material transport process.

  As described above, the transfer material gripping unit 610 grips the transfer material S before the transfer material S is inserted between the secondary transfer nips of the transfer belt 40 and the secondary transfer roller 61, and It operates to release the gripped transfer material S after it is inserted between the secondary transfer nips with the transfer roller 61. The transfer material S that has passed through the secondary transfer nip reliably separates the transfer material S from the secondary transfer roller 61 when the transfer material gripping portion 610 operates as shown in FIG. It can be reliably guided to the material transport process. In general, in an image forming process using a liquid developer, the transfer material S on which the toner image is transferred at the secondary transfer nip is attached to either the secondary transfer roller 61 or the transfer belt 40. Although peeling may be difficult, the transfer material S can be reliably peeled from each component by the operation of FIG.

  The transfer material S released by the transfer material gripping part 610 as described above is then transported to the transfer unit 90, and a transport means for performing this transport will be described. FIG. 4 is a diagram for explaining the operation of the transfer material transport unit used in the image forming apparatus according to the embodiment of the present invention. In FIG. 4, 210 is a first suction device, 211 is a housing portion, 212 is a suction surface, 215 is an airflow generating portion, 230 is a transfer material transport device, 231 is a housing portion, 232 is a suction surface, and 233 is a partition member. 235 is an air flow generation unit, 250 is a transfer material conveyance member, 251 is a transfer material conveyance member drive roller, 252 and 253 are transfer material conveyance member stretching rollers, 270 is a second suction device, 271 is a housing unit, and 272 is The suction surface, 275 is an airflow generation unit, 400 is a blower, 401 is a housing unit, 402 is an opening, and 405 is an airflow generation unit.

The first suction device 210 has a casing 211 to which an airflow generator 215 such as a sirocco fan is attached. The airflow generator 215 causes the outside of the casing 211 to be removed from the space R1 in the casing 211. The exhaust can be performed. The lower surface side of the housing 211 is a suction surface 212 having a plurality of ventilation holes on one surface. The first suction device 210 operates the air flow generation unit 215 to generate the suction force as shown in A by performing the exhaust as shown by a outside the casing unit 211. By this suction force, the transfer material S onto which the toner image has been transferred is held on the suction surface 212 against gravity. The suction force is such that the transfer material S is held on the suction surface 212, but the transfer material S is prevented from advancing against the force by which the transfer material S is pushed out from the secondary transfer nip. is not.

  The transfer material transport device 230 is generally configured by a housing portion 231 to which an airflow generating portion 235 such as a sirocco fan is attached, a transfer material transport member 250 disposed around the housing portion 231, and the like. In the transfer material transport device 230, the airflow generation unit 235 can exhaust air from the space R <b> 2 in the housing unit 231 to the outside of the housing unit 231.

  The lower surface side of the housing portion 231 is a suction surface 232 having a plurality of air holes provided on one surface. Along with the exhaust operation b of the airflow generation portion 235, the suction surface 232 has a suction force as shown at B. appear. At this time, due to the action of the partition wall member 233 provided in the housing portion 231, exhaust is performed relatively evenly from the space R <b> 2 in the housing portion 231, and the suction force on the suction surface 232 is also uneven depending on the location. To prevent this from occurring.

  The transfer material transport member 250 disposed around the casing 231 is an endless belt provided with a plurality of air holes (not shown) penetrating from one main surface to the other main surface. The transfer material conveying member driving roller 251 for applying a driving force to the transfer material and the transfer material conveying member stretching rollers 252 and 253 are stretched. The transfer material conveyance member 250 moves in the direction of the arrow in the figure as the transfer material conveyance member drive roller 251 rotates. This movement speed is substantially the same as the speed of the image forming process. The axial length of the transfer material conveyance member 250 (the width of the transfer material conveyance member 250) is configured to be longer than the width of the transfer material having the maximum width that can be handled by the image forming apparatus.

  The suction force on the suction surface 232 of the housing portion 231 also acts from the vent hole of the transfer material transport member 250, so that the transfer material S to which the toner image has been transferred is transported by the transfer material transport member 250 against gravity. While being held on the surface P, it is transported on the transport surface P as the transfer material transport member 250 is moved by the driving force of the transfer material transport member driving roller 251. An area between the transfer material conveyance member stretching roller 252 and the transfer material conveyance member driving roller 251 of the transfer material conveyance member 250 is used as a conveyance surface P for conveying the transfer material S.

  The second suction device 270 includes a housing part 271 to which an airflow generation unit 275 such as a sirocco fan is attached. By this airflow generation unit 275, the outside of the housing part 271 is separated from the space R3 in the housing part 271. To exhaust. The lower surface side of the housing portion 271 is a suction surface 272 having a plurality of air holes provided on one surface, and a suction force as shown in C is obtained by the exhaust operation c of the air flow generation unit 275 of the second suction device 270. Can be generated. With this suction force, the transfer material S onto which the toner image has been transferred is held on the suction surface 272 against gravity. This suction force is such that the transfer material S is held on the suction surface 272, but is not so great as to prevent the transfer material S from being conveyed against the force accompanying the transfer material S being conveyed.

  The transfer material conveyance means including the first suction device 210, the transfer material conveyance device 230, the second suction device 270, and the like conveys the transfer material with the surface on which the toner image of the transfer material is transferred vertically below.

The blower 400 is for discharging air into the space between the transfer belt 40 and the secondary transfer roller 61 near the outlet of the secondary transfer nip. Air is sent into a space R4 in 401. The casing 401 is provided with an opening 402 extending in the axial direction of the rollers, and the air sent into the casing 401 due to the airflow generation operation d of the airflow generator 405 is the opening 402. To D as shown in FIG. The air discharge force at this time is adjusted so that the transfer material S to which the toner image is transferred does not sag against gravity and the transfer material S does not flutter with the force of air.

  Next, the operation of the transfer material transport unit in the present embodiment configured as described above will be described. FIG. 4 shows the state in which the transfer material S is delivered from the secondary transfer nip of the secondary transfer unit 60 to the conveying means immediately after the transfer material S conveyance direction tip (SO) is discharged, that is, from the secondary transfer unit 60 side. It shows the state immediately after As shown in the figure, the transfer material S is held on the suction surface 212 without falling by the suction force A of the suction surface 212 generated in accordance with the operation a of the air flow generation unit 215, while falling from the secondary transfer unit 60 side. It is conveyed so as to slide on the suction surface 212 by the force of the feeding operation.

  Under the force of the feeding operation from the secondary transfer unit 60 side, the leading end portion in the transport direction of the transfer material S transported while sliding on the suction surface 212 of the first suction device 210 reaches the transfer material transport device 230 side. Then, the transfer material S is held by the suction force B on the transport surface P of the transfer material transport member 250 and advances along the transport surface P toward the fixing unit 90 as the transfer material transport member 250 moves. .

  The transfer material S transported on the transport surface P of the transfer material transport device 230 passes through the suction surface 272 of the second suction device 270 and passes between the fixing nip formed by the heating roller 91 and the pressure roller 92 in the fixing unit 90. Enter. The transfer material S that has passed through the fixing nip is fused with a toner image to become a permanent visible image.

  Next, control of the image forming apparatus according to the present invention will be described. FIG. 5 is a diagram showing an outline of a control block in the image forming apparatus according to the embodiment of the present invention. In FIG. 5, reference numeral 140 denotes an image formation controller unit, 141 denotes a toner amount calculation unit, 145 denotes a transfer material type information storage unit, 146 denotes a temperature sensor, 147 denotes a humidity sensor, 150 denotes a main control unit, 151, 153, 157, 158. Denotes an air volume control unit, 160 denotes a secondary transfer roller control unit, and 170 denotes a developing device control unit.

  The main control unit 150 is a main controller for performing each control of the image forming apparatus according to the present invention. As such a main control unit 150, a general-purpose information processing apparatus including a CPU, a RAM, a ROM, and the like is used, and a program for causing the CPU to execute an operation of outputting a command to a predetermined block based on input predetermined information Can be realized by storing in advance in the ROM.

  The image forming controller unit 140 controls exposure in the exposure units 12Y, 12M, 12C, and 12K based on the image signal input to the image forming apparatus. The image forming controller unit 140 further includes: A toner amount calculation unit 141 that calculates the amount of toner used that is expected from the exposure amount and exposure timing when performing image formation is provided. With such a toner amount calculation unit 141, the amount of toner transferred to the entire transfer material S can be predicted. Data relating to the toner amount calculated by the toner amount calculation unit 141 is transmitted to the main control unit 150, and the main control unit 150 side receiving the data appropriately outputs a control command based on the data.

The air volume control units 151, 153, 157, and 158 include an airflow generation unit 215 of the first suction device 210, an airflow generation unit 235 of the transfer material transport device 230, an airflow generation unit 275 of the second suction device 270, and the air blower 400. The air volume at the time of air flow generation in the air flow generation unit 405 is controlled. More specifically, the air volume control unit is a controller that performs speed control of a motor provided in a fan as each air flow generation unit. The main control unit 150 outputs control commands to these air volume control units 151, 153, 157, and 158 to control the air flow generated by the respective air flow generation units. This makes it possible to freely control the suction force with respect to the transfer material or the amount of discharge air with respect to the transfer material.

  The secondary transfer roller control unit 160 is based on the control command from the main control unit 150, the rotational peripheral speed of the secondary transfer roller 61, the operation timing of the gripping member 611 in the transfer material gripping unit 610, and the transfer material peeling member 640. Control the operation timing of the. Such a secondary transfer roller control unit 160 can freely change the timing at which the transfer material gripping unit 610 grips the transfer material or the timing at which the transfer material is released.

  The belt drive roller controller 161 controls the rotational peripheral speed of the belt drive roller 41 based on a control command from the main controller 150. This rotational peripheral speed is equal to the moving speed of the transfer belt 40 wound around the belt drive roller 41. Further, when the speed fluctuation of the belt driving roller 41 is detected, the rotational torque of the belt driving roller 41 is controlled to be kept constant by adjusting the driving torque of the belt driving roller 41. By stabilizing the moving speed of the transfer belt 40, it is possible to improve the quality of an image to be formed.

  Next, a predetermined pressure is applied at the secondary transfer nip in the secondary transfer portion (secondary transfer unit) 60 composed of the secondary transfer roller 61 provided with the recess 605 for accommodating the transfer material gripping portion 610. A structure for regulating the position between the secondary transfer roller 61 and the belt driving roller 41 will be described. 6 and 7 are diagrams for explaining the operation of the secondary transfer unit 60 in the image forming apparatus according to the embodiment of the present invention. In any of the drawings, (A) is a view of the secondary transfer unit 60 as viewed from the side of the apparatus, and (B) is a diagram showing a schematic cross section of the secondary transfer unit 60. FIG. 6 and 7, 650 is a contact member, 670 is a rotation support shaft portion, 671 is a frame member, 672 is an urging member, 689 is a roller shaft portion of the belt driving roller 41, and 690 is a support member. ing.

  In the secondary transfer unit 60, the roller shaft portion 602 of the secondary transfer roller 61 is rotatably attached to the frame member 671 at both ends thereof. Further, the frame member 671 is rotatable about the rotation support shaft portion 670 and is urged by the urging member 672 in the direction of the arrow in the figure. With such a structure, the secondary transfer roller 61 is biased toward the belt driving roller 41 so that a predetermined pressure can be applied to the secondary transfer nip between the belt driving roller 41 and the secondary transfer roller 61. It has become. By such transfer pressure and transfer bias in the secondary transfer nip, the toner particles on the transfer belt 40 are efficiently transferred to the transfer material side in the secondary transfer nip.

  Two contact members 650 are provided at both ends of the roller shaft portion 602 of the secondary transfer roller 61. Two support members 690 are provided at both ends of the roller shaft portion 689 of the belt driving roller 41 so as to correspond to the contact member 650. As shown in FIGS. 6 and 7B, the contact member 650 and the support member 690 are arranged so that their positions in the axial direction are aligned.

  FIG. 8 shows configurations of the contact member and the support member according to the embodiment of the present invention. The contact member 650 has a shape as shown in the figure, and is provided with a contact surface 663 whose distance from the rotation center O of the secondary transfer roller 61 is R2. On both sides of the contact surface 663, a first delivery surface 661 for suppressing an impact when starting to contact the support member 690 with the belt driving roller 41 and an impact when separating from the non-contact member 690 are suppressed. A second delivery surface 662 is formed.

The contact surface 663 is provided corresponding to a region (contact region C3) where the concave portion 605 is opened in the secondary transfer roller 61 when viewed from the roller axial direction. When the concave portion 605 is disposed so as to face the belt driving roller 41 (or the transfer belt 40) in accordance with the operation of the apparatus, the contact surface 663 (contact region C3) is connected to the support member 690 on the belt driving roller 41 side. By the contact, the support member 690 receives the urging pressure of the secondary transfer roller 61, and the distance and the positional relationship between the secondary transfer roller 61 and the belt driving roller 41 are maintained.

  In this embodiment, the sum of the radius R1 of the secondary transfer roller and the radius r1 of the belt driving roller 41 is substantially equal to the sum of the radius R2 at the contact surface 663 of the contact member 650 and the radius r2 of the support member 690. It is set to be. With such a configuration, even when the concave portion 605 of the secondary transfer roller 61 is opposed to the belt driving roller 41, the contact member 650 and the support member 690 are in contact with each other, and the virtual circumference that connects both ends of the concave portion 605 is exactly the same. As in the case where the peripheral length B of the surface is provided, the positional relationship between the secondary transfer roller 61 and the belt driving roller 41 can be maintained.

  The support member 690 is a member having an outer periphery whose distance from the roller rotation center O ′ of the belt driving roller 41 is r2, and the contact surface is lubricated in order to suppress resistance at the time of contact with the contact member 690. A sliding portion such as a bearing that is rotated is provided. As each roller rotates, the secondary transfer roller 61 and the belt drive roller 41 receive the load of the secondary transfer roller 61 that is in contact with the contact surface 663 of the contact member 650 and biased by the biasing member 672. The distance and the positional relationship between them are maintained.

  The secondary transfer unit 60 repeats the state shown in FIG. 6 → the state shown in FIG. 7 → as the rollers rotate. FIG. 6 shows a state where the recess 605 does not face the belt driving roller 41 (or the transfer belt 40). At this time, the urging force from the urging member 672 is applied to the secondary transfer nip, a predetermined transfer pressure is ensured, and further, between the secondary transfer roller 61 and the belt driving roller 41. An appropriate transfer bias is applied, and the toner particles on the transfer belt 40 are transferred to the transfer material side at the secondary transfer nip. In this state, the abutting member 650 and the support member 690 are completely separated from each other, and position restriction by them is not working.

  FIG. 7 shows a state where the concave portion 605 faces the belt driving roller 41 (or the transfer belt 40). At this time, the contact surface 663 (contact region C3) of the contact member 650 is in contact with the support member 690, and the biasing pressure of the secondary transfer roller 61 biased by the biasing member 672 is supported. The member 690 receives and the distance and positional relationship between the secondary transfer roller 61 and the belt drive roller 41 are maintained.

  According to the present embodiment described above, the secondary transfer roller 61 is urged toward the belt drive roller 41, but the shaft portion of the secondary transfer roller 61 has the contact member 650, and the belt drive roller 41. Since the support member 690 is disposed on the shaft portion of the second transfer roller 61, the secondary transfer roller 61 can apply a predetermined pressure to the transfer nip when the recess 605 is not in contact with the transfer belt 40, and the recess 605. When the roller is opposed to the transfer belt, the positional relationship between the secondary transfer roller 61 and the belt driving roller 41 can be maintained.

In this embodiment, the contact member is provided on the secondary transfer roller 61 side and the support member 690 is provided on the belt drive roller 41 side as described above, so that the secondary transfer roller 61 having the recess 605 is rotated. It is possible to suppress vibration. However, the impact generated when the secondary transfer roller 61 is separated from the transfer belt 40 at one end of the recess 605 and when the secondary transfer roller 61 and the transfer belt 40 contact at the other end of the recess is completely It is difficult to remove, and the tension applied to the transfer belt 40 is different between the state where the secondary transfer roller 61 and the transfer belt 40 are in contact with each other and the state where the transfer belt 40 is separated. As described above, a change in impact or tension on the transfer belt 40 reveals a fluctuation in the speed of the transfer belt 40.

  FIGS. 9 and 10 are diagrams for explaining such a change in the state of the transfer belt 40, and FIG. 9 is a diagram illustrating a state in which the secondary transfer roller 61 is separated from the transfer belt 40. FIG. FIG. 10 is a diagram showing how the speed of the transfer belt 40 fluctuates.

  FIGS. 9A and 9B are views showing the state of rotation of the secondary transfer roller 61. In the drawing, the secondary transfer roller 61 rotates clockwise. In the secondary transfer roller having the concave portion 605, the state where the secondary transfer roller 61 and the transfer belt 40 are in contact with each other as shown in FIG. 9A is separated from the state shown in FIG. 9B. When changing, the transfer belt 40 is released from the secondary transfer roller 61, whereby the tension applied to the transfer belt 40 changes, and as a result, the speed fluctuation of the transfer belt 40 occurs. FIG. 10 is a diagram showing how the transfer belt 40 fluctuates in speed, and shows how the transfer belt 40 fluctuates when the transfer belt 40 is separated from the secondary transfer roller 61. In this measurement example, the abutting member 650 in the secondary transfer roller 61 and the support member 690 in the belt driving roller 41 described with reference to FIGS. 6 and 7 are not provided for later comparison, and in FIG. The belt drive roller controller 161 described is not controlled at the time of speed fluctuation.

  As shown in FIG. 10, the transfer belt 40 that has been moving at a constant speed is separated from the secondary transfer roller 61, so that the fluctuation that attenuates after the movement speed instantaneously increases is repeated several times. Return to a constant speed. Such a change in the speed of the transfer belt 40 causes a shift in the image being transferred between the photoconductor 10 and the transfer belt 40, thereby deteriorating the image to be formed. In the present embodiment, the concave portion provided in the secondary transfer roller 61 so that the image being transferred is not shifted due to the speed fluctuation of the transfer belt 40 when the transfer belt 40 is separated from the secondary transfer roller 61. The circumferential length of the virtual peripheral surface 605 is larger than the distance of the transfer belt 40 between the transfer position of the photoconductor 10 and the secondary transfer position (nip portion) of the secondary transfer roller 61. is there.

  Further, as a precondition for that, that is, as a condition that the secondary transfer roller 61 is separated from the transfer belt 40 at the position of the recess 605 when the secondary transfer roller 61 rotates, the circumference of the virtual peripheral surface of the recess 605 is secondary. The width of the secondary transfer nip formed when the transfer roller 61 and the transfer belt 40 contact each other is larger than the width in the transfer material conveyance direction.

  By adopting such a configuration, it is possible to transfer the image from the photoconductor 10K to the transfer belt 40 while avoiding the speed fluctuation of the transfer belt 40 that occurs when the concave portion 605 is made large. Further, since an image can be formed from the end of the transfer material gripped by the transfer material gripping portion 610, it is possible to reduce the margin of the transfer material.

  An embodiment of such an image forming apparatus will be described with reference to FIG. This figure is an enlarged view of a part of the image forming apparatus. In particular, the arrangement of the photoconductor 10K and the secondary transfer roller 61 is shown. In the present embodiment, the condition is that the nip width formed when the secondary transfer roller 61 and the transfer belt 40 come into contact with each other is smaller than the concave portion 605 of the secondary transfer roller 61. Under such conditions, a period in which the transfer belt 40 is separated from the secondary transfer roller 61 is generated, and as a result, a speed fluctuation of the transfer belt 40 that is a subject of the present invention occurs.

Here, a method for measuring the nip width formed by the contact between the secondary transfer roller 61 and the transfer belt 40 will be described. First, the two-component curing for mold forming is performed on the portion of the secondary transfer roller 61 where the nip is formed. The mold silicone rubber is applied, and the silicone rubber is cured in a state where a nip portion is formed by the belt driving roller 41 and the secondary transfer roller 61. In the present embodiment, an injection type exafine (manufactured by GC Corporation) was used as the two-component curable silicone rubber. Subsequently, the cured silicone rubber is taken out from the nip portion, and the width of the nip forming portion (the portion where the silicon rubber is thinned) is measured using a caliper.

  The precondition is that the circumferential length B of the virtual circumferential surface of the concave portion 605 of the secondary transfer roller 61 is larger than the nip width measured in this way. In the image forming apparatus shown in FIG. 11, the nip width is sufficiently small, and the layout satisfies this precondition.

  The circumferential length B of the virtual circumferential surface of the concave portion 605 of the secondary transfer roller 61 is an image from the transfer belt 40 to the secondary transfer roller 61 from the transfer position where the photoconductor 10K transfers the image to the transfer belt 40. It is assumed that the distance is larger than the moving distance F of the transfer belt 40 to the transfer position. By adopting such a configuration, image transfer from the photoconductor 10 to the transfer belt 40 is started after the speed fluctuation of the transfer belt 40 generated when the secondary transfer roller 61 and the transfer belt 40 are separated from each other. Therefore, it is possible to prevent the image from being shifted from the transferred image. Furthermore, since the concave portion 605 is larger than the moving distance F, the image can be transferred from the end of the transfer material gripped by the transfer material gripping portion 610, and the margin of the transfer material can be minimized. It becomes.

  FIG. 11 shows the moving distance F of the transfer belt 40 from the transfer position at which the photoconductor 10K transfers an image to the transfer belt 40 to the image transfer position from the transfer belt 40 to the secondary transfer roller 61. ing. Since the secondary transfer roller 61 and the transfer belt 40 and the photosensitive member 10K and the transfer belt 40 are in contact with each other with a nip width, the moving distance F of the transfer belt 40 has a margin corresponding to the nip width. It is preferable to design.

  Further, as shown in FIG. 11, the relationship between the moving distance F of the transfer belt 40 and the peripheral length B of the virtual peripheral surface of the recess 605 is applied to the photoconductor 10K that develops the latent image with a black developer. It is preferred that The black developer is required to contain carbon black or iron oxide as its component. By applying the distance relationship of the present invention to the black developer in which the image shift is conspicuous as described above, it is possible to suppress image deterioration more effectively.

  FIG. 12 is a diagram for explaining the relationship of distance in the entire image forming apparatus. In this image forming apparatus, the distances A between adjacent photoconductors 10 are arranged to be equal to each other, each distance A is set to 220 [mm], and the circumference B of the virtual peripheral surface of the recess 605 is set to 100. Designed as [mm]. The peripheral length E of the secondary transfer roller 61 is 500 [mm].

  In FIG. 10, the contact belt 650 in the secondary transfer roller 61 and the support member 690 in the belt drive roller 41 are not provided, and the transfer belt when the belt drive roller control unit 161 does not perform control at the time of speed fluctuation. Although the state of the speed variation of 40 has been described, the speed variation of the transfer belt 40 is suppressed by using the contact member 650 and the support member 690 or by controlling the speed variation by the belt drive roller control unit 161. It becomes possible to do.

  In FIG. 13, a contact member 650 is provided on the transfer roller 61 side and a support member 690 is provided on the belt drive roller 41 side. When the transfer roller 61 is separated from the transfer belt 40, the contact member 650 and the support member 690 are contacted. FIG. 6 is a diagram showing how the speed of the transfer belt 40 fluctuates when the configuration to be adopted is adopted. The broken line shows the speed fluctuation of the transfer belt 40 shown in FIG. 10. By providing the contact member 650 and the support member 690, the amplitude of the speed fluctuation amount compared to the speed fluctuation of the broken line. And the time required for the transfer belt 40 to return to a predetermined speed can be shortened.

  FIG. 14 is a diagram showing the state of speed fluctuation when the belt drive roller controller 161 performs speed control on the belt drive roller 41. As in FIG. 13, the broken line indicates the speed fluctuation of the transfer belt shown in FIG. When the belt driving roller control unit 161 detects that the speed fluctuation has occurred in the belt driving roller 41, the belt driving roller control unit 161 controls the belt driving roller 41 to return to a constant speed. As described above, even when the belt drive roller control unit 161 is used, the amplitude of the speed fluctuation amount is reduced, and the time required to return to the predetermined speed can be shortened, so that the transfer belt 40 can be driven stably. Become.

  The embodiment of the present invention has been described above. According to the present invention, when the concave portion 605 for arranging the transfer material gripping portion 610 is provided in the secondary transfer roller 61, the transfer belt 40 is subjected to the secondary transfer. When a transfer deviation that occurs due to the separation from the roller 61 occurs, the transfer of the image from the photoconductor 10K to the transfer belt 40 can be avoided, the image deviation is prevented, and the image is formed by the image forming apparatus. Image quality can be improved.

  Note that although various embodiments have been described in this specification, embodiments configured by appropriately combining the configurations of the respective embodiments are also included in the scope of the present invention.

10Y, 10M, 10C, 10K ... photosensitive member (image carrier), 11Y, 11M, 11C, 11K ... corona charger, 12Y, 12M, 12C, 12K ... exposure unit, 13Y, 13M, 13C, 13K ... first photosensitive Body squeeze roller, 13Y ', 13M', 13C ', 13K' ... Second photoreceptor squeeze roller, 14Y, 14Y ', 14M, 14M', 14C, 14C ', 14K, 14K', ... Photoconductor squeeze roller cleaning blade , 18Y, 18M, 18C, 18K ... Photoconductor cleaning blade, 20Y, 20M, 20C, 20K ... Developing roller, 21Y, 21M, 21C, 21K ... Developing roller cleaning blade, 22Y, 22M, 22C, 22K ... Compact corona generator , 30Y, 30M, 30C, 30K ... developing device, 31Y 31M, 31C, 31K ... developer container, 32Y, 32M, 32C, 32K ... anilox roller, 33Y, 33M, 33C, 33K ... regulating blade, 34Y, 34M, 34C, 34K ... auger (supply roller), 40 ... transfer belt 41 ... belt drive roller, 42 ... tension roller, 49 ... transfer belt cleaning blade, 50Y, 50M, 50C, 50K ... primary transfer part, 51Y, 51M, 51C, 51K ... primary transfer backup roller, 60 ... secondary Transfer unit 61... Secondary transfer roller 62. Secondary transfer roller cleaning blade 74... (Cleaning) blade holding member 85. Secondary transfer unit collection and storage unit 90. Fixing unit 91. Heating roller 92. Pressure roller, 101, 101 '... gate roller, DESCRIPTION OF SYMBOLS 02 ... Transfer material guide, 140 ... Image formation controller part, 141 ... Toner amount calculation part, 145 ... Transfer material type information storage part, 146 ... Temperature sensor, 147 ... Humidity sensor, 150 ... Main control part, 151, 153, 157 158 ... Air volume control unit, 160 ... Secondary transfer roller control unit, 210 ... First suction device, 211 ... Housing part, 212 ... Suction surface, 215 ... Airflow generation part, 230 ... Transfer material transport device, 231 ... Housing Body part, 232 ... Suction surface, 233 ... Partition member, 235 ... Airflow generating part, 250 ... Transfer material conveying member, 251 ... Transfer material conveying member drive roller, 252, 253 ... Transfer material conveying member stretching roller, 270 ... First 2 suction device, 271 ... housing part, 272 ... suction surface, 275 ... air flow generation part, 400 ... air blower, 401 ... housing part, 402 ... opening, 405 ... air flow generation part, 601 ... b Roller base material, 602... Roller shaft, 605. Recess, 607. Elastic member, 610. Transfer material gripping part, 611. Holding member, 612. Holding member receiving part, 640 ... Transfer material peeling member, 650. 663... Contact surface, 670... Rotating support shaft portion, 671... Frame member, 672.

Claims (6)

An image carrier for carrying an image;
A transfer belt onto which the image carried on the image carrier is transferred;
A transfer nip having a recess in the axial direction of the peripheral surface, and a transfer material gripping part for gripping the transfer material is provided in the recess, and an image transferred to the transfer belt is formed by contact with the transfer belt A transfer roller for transferring to the transfer material at a portion,
The circumferential length of the virtual circumferential surface of the recess corresponding to the circumferential surface of the transfer roller is larger than the width of the transfer nip portion in the transfer material conveyance direction, and the transfer belt onto which the image on the image carrier is transferred. An image forming apparatus, wherein the distance is larger than a distance of the transfer belt between a transfer position and a position of the transfer nip portion. A second image carrier for carrying an image;
The image carried on the second image carrier is transferred to the transfer belt, and the image carried on the second image carrier is carried on the transfer belt onto which the image has been transferred. The image forming apparatus according to claim 1, wherein an image is transferred. The image carried on the image carrier is an image developed with a liquid developer having toner and carrier liquid,
The image forming apparatus according to claim 1, wherein the toner contains carbon black or iron oxide. A speed controller for controlling the moving speed of the transfer belt;
4. The control unit according to claim 1, further comprising: a control unit configured to start transfer of the image carried on the image carrier to the transfer belt after controlling the moving speed of the transfer belt by the speed control unit. The image forming apparatus according to claim 1. A contact member disposed in the axial direction of the recess of the transfer roller;
A stretching roller that contacts the transfer roller via the transfer belt;
5. The image forming apparatus according to claim 1, further comprising a support member that is disposed in an axial direction of the stretching roller and that abuts against the abutting member. 6. Transfer the image carried on the image carrier onto the transfer belt,
The image transferred to the transfer belt is moved to a transfer nip formed by contact between the transfer belt and a transfer roller having a recess on the peripheral surface,
The transfer material gripped by the transfer material gripping portion disposed in the recess by the transfer roller having a peripheral length of a virtual peripheral surface corresponding to the peripheral surface of the transfer roller of the recess different from the moving distance of the image An image forming method, wherein the image is transferred to a surface.

Images