JP2011164520A - Image forming apparatus and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent image disturbance and jam by appropriately controlling the posture of a transfer material released from a grip, in an image forming apparatus and image forming method in which a transfer material is passed through a transfer nip between a transfer roller and an image carrier belt. <P>SOLUTION: The image forming apparatus includes: the image carrier belt 31 carrying an image; the transfer roller 4 having a recess 41 on its periphery, rotated around a rotation shaft 4211, forming a transfer nip NP when the periphery of this roller, except the recess 41, contacts the image carrier belt 31 via a transfer material S, and having a gripping member 44 in the recess 41, which grips a transfer material S or releases it vertically below an imaginary horizontal plane including the center of the rotation shaft 4211 and perpendicular to the vertical direction; an air current generating portion 8 for blowing an air current against a transfer material S passed through the transfer nip NP; and a control portion for blowing an air current from the air current generating portion 8 against a transfer material S when the transfer material S is released from the gripping member 44. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus and an image forming method for passing a transfer material through a transfer nip between a transfer roller and an image carrier belt.

  As an image forming apparatus for transferring an image formed on an image carrier onto a transfer material, for example, there is one described in Patent Document 1. The apparatus described in Patent Document 1 is a so-called liquid development type image forming apparatus that visualizes an electrostatic latent image with a liquid developer containing toner particles and a carrier liquid. In this apparatus, a transfer material is gripped by a gripper (grip member) provided on a part of the peripheral surface of a pressure roller (corresponding to a transfer roller), and the transfer material is wound around the pressure roller so as to be a drum-shaped intermediate transfer body The image is transferred onto the transfer material by passing through the nip with the (image carrier). According to such a configuration, since the transfer material is passed through the nip while being mechanically gripped, there is no possibility of the transfer material sticking to the image carrier even if a strong transfer pressure is applied at the nip.

  On the other hand, in the liquid developing type image forming apparatus described in Patent Document 2, an image is transferred to a transfer material in a transfer nip formed by an intermediate transfer belt that carries an image and a transfer belt. At this time, the transfer material is peeled off from the intermediate transfer belt by blowing an air current to the transfer material sent from the transfer nip.

Japanese translation of PCT publication No. 2000-508280 (for example, FIG. 2A) JP2009-205131A (for example, FIG. 4)

  A configuration in which the transfer roller having the gripping member described in Patent Document 1 and the intermediate transfer belt described in Patent Document 2 are combined can be considered. In this case, the following problem may occur. In other words, in the configuration of Patent Document 2, the transfer nip is formed by bringing the belts into contact with each other. Therefore, the transfer material passing through the transfer nip is conveyed in a substantially flat state and is received by the rear belt conveyance device. Passed. On the other hand, in the transfer roller described in Patent Document 1, the transfer material is conveyed so as to be wound around the peripheral surface of the roller. Therefore, the posture of the transfer material follows the peripheral shape of the roller while being held by the holding member, but the posture is not necessarily maintained after the holding is released. For this reason, there is a possibility that the transfer material released from gripping hangs down and touches the surrounding members to disturb the transferred image, or to cause a jam due to poor conveyance.

  According to some aspects of the present invention, in the image forming apparatus and the image forming method in which the transfer material is passed through the transfer nip between the transfer roller and the image carrier belt, the above problem is solved and the grip is released. The present invention provides a technique that can appropriately control the posture of a transfer material to prevent image distortion and jamming.

  In one aspect of the image forming apparatus according to the present invention, in order to solve the above-described problem, an image carrier belt that carries an image, a circumferential surface having a concave portion, and rotating around a rotation axis, the circumferential surface different from the concave portion Is in contact with the image carrier belt via a transfer material to form a transfer nip, and grips the transfer material, or is below the virtual horizontal plane including the center of the rotation axis and perpendicular to the vertical direction. A transfer roller having a gripping member for releasing the transfer material disposed in the recess, an airflow generating portion for blowing an airflow to the transfer material that has passed through the transfer nip, and the transfer material when the transfer material is released from the gripping member And a control unit for blowing an air flow from the air flow generation unit.

  In the invention configured as described above, the posture can be maintained by causing the transfer material to follow the peripheral surface of the transfer roller by blowing the airflow onto the transfer material released from the grip. For this reason, there is no fear that the transfer material contacts peripheral members and disturbs the image, or a jam occurs due to poor conveyance. In particular, in a configuration in which the transfer material is released vertically below the virtual horizontal plane passing through the central axis of the transfer roller, it is highly possible that the released transfer material hangs down due to gravity. Therefore, it is possible to prevent the transfer material from drooping.

  In this invention, for example, the controller has a guide portion that guides the transfer material released from the gripping member, and the control unit removes the transfer material from the airflow generating portion while the transfer material moves to the guide portion after the transfer material is released. An air flow may be generated. In such a configuration, an air current is blown onto the transfer material and pressed against the peripheral surface of the transfer roller, whereby the transfer material can be transported by the rotation of the transfer roller and reliably fed into the guide portion.

  For example, the control unit may generate an air flow from the air flow generation unit while holding the transfer material with the holding member, or generate an air flow from the air flow generation unit after the holding member releases the transfer material. You may make it make it. In the configuration in which the airflow is generated before the transfer material is released, the airflow for controlling the posture of the transfer material is blown before the release of the grip, so that the posture control of the transfer material can be more reliably performed. it can. Further, in the configuration in which the airflow is generated after the transfer material is released, for example, the release by the gripping member is detected, or the airflow generation unit may be controlled using a control signal for release. Simple.

  Further, for example, a signal output unit that outputs a signal synchronized with the rotation of the transfer roller may be provided, and the control unit may control the generation of the airflow of the airflow generation unit based on the signal. Since the gripping and releasing by the gripping member are performed in synchronization with the rotation of the transfer roller, the timing of airflow generation can also be controlled based on a signal relating to the rotation phase of the transfer roller.

  In this case, for example, the controller may be configured to control the release of the transfer material from the gripping member based on the signal output from the signal output unit. In such a configuration, since the control unit manages the timing at which the gripping member releases the transfer material, it is possible to appropriately manage and execute the release of the transfer material and the generation of airflow.

  Further, for example, a transport unit that transports the transfer material released from the gripping member is provided, and the control unit is configured to control the flow rate of the airflow from the airflow generation unit at the transport unit after the transport unit starts transporting the transfer material. The flow rate may be smaller than the flow rate of the airflow from the airflow generation unit before the transfer material is started to be conveyed. Since the effect of maintaining the posture of the transfer material can be expected also by being transported to the transport unit, the flow rate of the air flow by the air flow generation unit can be reduced after the transport is started. In this case, the flow rate may be reduced and spraying may be continued, or the air flow may be stopped.

  According to another aspect of the image forming method of the present invention, in order to solve the above-described problem, a transfer material is gripped by a gripping member disposed in the recess of a transfer roller having a recess on a peripheral surface, and the gripping member An image carried on the image carrier belt is transferred to the gripped transfer material at a transfer nip formed by an image carrier belt and the transfer roller, and the transfer material on which the image is transferred is transferred to the transfer material. It is characterized in that it is released from the gripping member below the virtual horizontal plane including the rotation center of the transfer roller and perpendicular to the vertical direction, and the airflow from the airflow generator is blown onto the transfer material.

  According to another aspect of the image forming method of the present invention, in order to solve the above-described problem, a transfer material is gripped by a gripping member disposed in the recess of a transfer roller having a recess on a peripheral surface, and the gripping member An image carried on the image carrier belt is transferred to the gripped transfer material at a transfer nip formed by an image carrier belt and the transfer roller, and an air flow is generated on the transfer material onto which the image has been transferred. The transfer material is released from the gripping member below the virtual horizontal plane including the rotation center of the transfer roller and perpendicular to the vertical direction in a state where the airflow is blown from the section and the airflow is blown. It is said.

  These image forming methods are different in that the airflow is blown toward the transfer material after being released from the gripping member or the gripping is released while blowing the airflow. In any configuration, similar to the above-described invention of the image forming apparatus, it is possible to maintain the posture by blowing an air flow onto the released transfer material so that the transfer material follows the peripheral surface of the transfer roller. There is no risk of disturbing the image by contacting peripheral members or causing jamming due to poor conveyance.

1 is a diagram illustrating a first embodiment of an image forming apparatus according to the present invention. The block diagram which shows the electric constitution of the apparatus of FIG. The perspective view which shows the whole structure of a secondary transfer roller. The figure which shows the opening / closing mechanism of a holding part. FIG. 3 is a first diagram illustrating a relationship between a rotation phase of a secondary transfer roller and an opening / closing state of a gripping portion. FIG. 9 is a second diagram showing the relationship between the rotation phase of the secondary transfer roller and the open / close state of the gripping portion. The figure which shows the mode of the attitude | position control by a ventilation unit. The figure which looked at the secondary transfer roller and the ventilation unit from the upper part. The figure which shows the operation | movement sequence of a ventilation unit. FIG. 5 is a diagram illustrating a second embodiment of an image forming apparatus according to the present invention. The figure which shows the principal part of 3rd Embodiment of the image forming apparatus concerning this invention. The figure which shows the principal part of 4th Embodiment of the image forming apparatus concerning this invention.

  FIG. 1 is a diagram showing a first embodiment of an image forming apparatus according to the present invention. FIG. 2 is a block diagram showing an electrical configuration of the apparatus of FIG. The image forming apparatus 1 includes four image forming stations 2Y (for yellow), 2M (for magenta), 2C (for cyan), and 2K (for black) that form images of different colors. The image forming apparatus 1 includes a color mode in which four color toners of yellow (Y), magenta (M), cyan (C), and black (K) are superimposed to form a color image, and only black (K) toner. And a monochrome mode for forming a monochrome image using can be selectively executed. In this image forming apparatus, when an image forming instruction is given from an external device such as a host computer to a controller 10 having a CPU, a memory, etc., the controller 10 controls each part of the apparatus to execute a predetermined image forming operation, and copy An image corresponding to the image formation command is formed on a sheet-like transfer material S such as paper, transfer paper, paper, and an OHP transparent sheet.

  Each of the image forming stations 2Y, 2M, 2C, and 2K is provided with a photosensitive drum 21 on which a toner image of each color is formed. The photosensitive drums 21 are arranged such that the rotation axis thereof is parallel or substantially parallel to the main scanning direction (direction perpendicular to the paper surface of FIG. 1), and a predetermined speed is indicated in the direction of arrow D21 in FIG. Is driven to rotate.

  Around each photosensitive drum 21, a charger 22 that is a corona charger that charges the surface of the photosensitive drum 21 to a predetermined potential and an electrostatic latent image by exposing the surface of the photosensitive drum 21 according to an image signal. An exposure unit 23 that forms an image, a developing unit 24 that visualizes the electrostatic latent image as a toner image, a first squeeze portion 25, a second squeeze portion 26, and an intermediate portion between the toner image and the transfer unit 3. A primary transfer unit that performs primary transfer onto the transfer belt 31, a cleaning unit that cleans the surface of the photosensitive drum 21 after transfer, and a cleaner blade are arranged in the order of rotation D21 of the photosensitive drum 21 (in FIG. 1, (Clockwise).

  The charger 22 does not come into contact with the surface of the photosensitive drum 21, and a conventionally well-known and commonly used corona charger can be used as the charger 22. When a scorotron charger is used as the corona charger, a positive wire current flows through the charge wire of the scorotron charger and a direct current (DC) grid charging bias is applied to the grid. When the photosensitive drum 21 is charged by corona discharge by the charger 22, the surface potential of the photosensitive drum 21 is set to a substantially uniform potential.

  The exposure unit 23 exposes the surface of the photosensitive drum 21 with a light beam in accordance with an image signal given from an external device to form an electrostatic latent image corresponding to the image signal. The exposure unit 23 can be constituted by a light beam from a semiconductor laser that is scanned by a polygon mirror, or a line head in which light emitting elements are arranged in the main scanning direction.

  Toner is applied to the electrostatic latent image formed in this manner from a developing roller 241 provided in the developing unit 24, and the electrostatic latent image is developed with toner. In the developing unit 24 of the image forming apparatus 1, toner development is performed using a liquid developer in which toner is dispersed in a carrier liquid in an approximate weight ratio of about 20%. The liquid developer used in this embodiment is a low-concentration (1 to 2 wt%) and low-viscosity volatility that is generally used in the past, using Isopar (trademark: Exon) as a carrier liquid. It is not an ionic liquid developer but a non-volatile liquid developer having a high concentration and high viscosity and having non-volatility at room temperature. That is, the liquid developer in the present embodiment is obtained by dispersing solid particles having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a thermoplastic resin in a liquid solvent such as an organic solvent, silicon oil, mineral oil, or edible oil. High viscosity with a toner solid content concentration of about 20% (HAAKE RheoStress RS600 is used, and the viscoelasticity at a shear rate of 1000 (1 / S) at 25 ° C. is 30 to 300 mPa · s. Liquid developer.

  A first squeeze portion 25 is disposed on the downstream side of the developing position in the rotation direction D 21 of the photosensitive drum 21, and a second squeeze portion 26 is disposed on the downstream side of the first squeeze portion 25. The squeeze rollers 25 and 26 are respectively provided with squeeze rollers. Each squeeze roller comes into contact with the surface of the photosensitive drum 21 to remove excess carrier liquid and fog toner from the toner image. In the present embodiment, the excess carrier liquid and fog toner are removed by the two squeeze portions 25 and 26. However, the number and arrangement of the squeeze portions are not limited to this, for example, one squeeze portion. May be arranged.

  The toner image that has passed through the squeeze portions 25 and 26 is primarily transferred to the intermediate transfer belt 31 by the primary transfer unit. The intermediate transfer belt 31 is stretched around a pair of belt conveying rollers 32 and 33 that are disposed apart from each other, and is rotated in a predetermined direction D31 by roller driving by a belt driving motor M3. More specifically, the right roller 32 in FIG. 1 among these belt transport rollers 32 and 33 is a drive roller, and a belt drive motor M3 is mechanically connected to the drive roller 32. In the present embodiment, a driver 11 is provided to drive the belt drive motor M3, and a drive signal corresponding to a command pulse given from the controller 10 is output to the belt drive motor M3 for position control. As a result, the drive roller (belt transport roller) 32 rotates in the arrow direction D32 in FIG. 1 at a peripheral speed corresponding to the command pulse, and the surface of the intermediate transfer belt 31 rotates in the direction D31 at a constant speed.

  The primary transfer unit has a backup roller 271. The backup roller 271 is disposed opposite to the photosensitive drum 21 across the intermediate transfer belt 31 at the primary transfer position TR 1 to transfer the toner image on the photosensitive drum 21. Transfer to the intermediate transfer belt 31. Then, the transfer of the toner image is executed by the transfer unit of each color, so that the toner images of each color on the photosensitive drum 21 are sequentially superimposed on the intermediate transfer belt 31 to form a full color toner image.

  The toner image thus transferred to the intermediate transfer belt 31 is conveyed to the secondary transfer position TR2. At the secondary transfer position TR2, the secondary transfer roller 4 is disposed so as to face the intermediate transfer belt 31 wound around the driving roller 32 of the transfer unit 3. As shown in FIG. 2, the secondary transfer roller 4 is rotationally driven by the secondary transfer roller drive motor M4 and rotates in the arrow direction D4 in FIG. The secondary transfer roller drive motor M4 is driven and controlled by a drive signal output from the driver 12 in response to a command pulse from the controller 10. Then, at the secondary transfer position TR2, a single-color or multi-color toner image formed on the intermediate transfer belt 31 is transferred from the gate roller 51 (a pair of rollers 51a and 51b) along the transfer path PT. Secondary transferred to S. Between the gate roller 51 and the secondary transfer position TR2, a sheet guide 52 for feeding the transfer material S to the secondary transfer position TR2 without contacting the secondary transfer roller 4 or the intermediate transfer belt 31 is disposed. ing.

  A photosensor cam 91 for detecting the rotational phase of the secondary transfer roller 4 is disposed on the rotary shaft 421 of the secondary transfer roller 4. The photo sensor cam 91 is formed in a disk shape having a slit-shaped notch 911 in a part of the peripheral surface, and rotates with the rotation of the secondary transfer roller 4. On the other hand, a photo sensor 92 made of, for example, a photo interrupter is provided on the apparatus housing side. Each time the notch 911 of the photo sensor cam 91 passes the detection position by the photo sensor 92 with the rotation of the secondary transfer roller 4, the photo sensor 92 generates a synchronization signal synchronized with the rotation of the secondary transfer roller 4. Output. As a result, the rotational phase of the secondary transfer roller 4 is detected, and the controller 10 controls the operation timing of each part of the apparatus based on this synchronization signal.

  The transfer material S on which the toner image is secondarily transferred is sent from the secondary transfer roller 4 to the transport mechanism 6 along the transport path PT. In the transport mechanism 6, the first suction unit 61, the transfer material transport unit 62, and the second suction unit 63 are sequentially arranged along the transport path PT, and these cooperate to transport the transfer material S to the fixing unit 7. To do. At this time, the transfer material S is conveyed while the upper surface opposite to the image transfer surface is adsorbed in a posture in which the image transfer surface to which the toner image has been transferred from the intermediate transfer belt 31 is directed vertically downward. Transported). In FIG. 1, the white arrows attached to the first suction unit 61, the transfer material transport unit 62, and the second suction unit 63 indicate the direction of the airflow formed when these units are operated to suck the transfer material S. Is shown. This is the same in the following drawings.

  Whether or not the transfer material S exists in the vicinity of the suction surface 611 of the first suction portion disposed adjacent to the rear of the secondary transfer roller 4 in the transport direction of the transfer material S along the transport path PT. A sheet detection sensor 612 is provided for detecting the above. The output signal of the sheet detection sensor 612 is input to the controller 10.

  In addition, in order to reliably feed the transfer material S on which the toner image has been secondarily transferred to the first suction unit 61 and to prevent image fouling, in this embodiment, the secondary transfer position TR2 and the first suction unit 61 are used. The air blowing unit 8 is arranged so as to face the secondary transfer roller 4 between the two. In the blower unit 8, the gripping portion of the secondary transfer roller 4 is discharged by discharging the airflow from the opening 83 of the housing portion 82 generated by the operation of the blower fan 81 that generates the airflow, as indicated by the white arrow. An air current is blown between the front end portion of the transfer material S released from the grip 44 and the intermediate transfer belt 31, and the transfer material S is separated from the intermediate transfer belt 31.

  Further, the peeled transfer material S is pressed against the peripheral surface of the secondary transfer roller 4 by an air current blown to the image transfer surface of the transfer material S, and is conveyed by the rotation of the secondary transfer roller 4. Thus, the leading end portion of the transfer material S is fed toward the first suction portion 61. Further, when the rear end portion of the transfer material S is discharged from the secondary transfer position TR2 due to the air current blown to the transfer material S, the rear end portion touches the intermediate transfer belt 31 and the like, and the image is stained. Can be prevented.

  Further, a fixing unit 7 is disposed on the downstream side of the transport path PT, that is, on the side opposite to the secondary transfer roller 4 with respect to the transport mechanism 6 (the left hand side in FIG. 1), and is transferred to the transfer material S. Heat or pressure is applied to the toner image, and the toner image is fixed to the transfer material S.

  A cleaner blade 391 is in contact with the intermediate transfer belt 31 to which the toner image is secondarily transferred. More specifically, the cleaner blade 391 hits the roller 33 around which the intermediate transfer belt 31 is wound downstream of the secondary transfer position TR2 in the transport direction D31 of the intermediate transfer belt 31 via the intermediate transfer belt 31. It touches. The cleaner blade 391 removes residual deposits such as toner and carrier liquid remaining on the surface of the intermediate transfer belt 31 after the secondary transfer.

  Further, the apparatus 1 rotates the gate roller 51 as shown in FIG. 2 in addition to the bias generating section that generates a bias voltage supplied to each section of the apparatus, the secondary transfer roller 4 and the belt driving roller 32 described above. A motor M5 for driving the motor M5, a driver 13 for driving the motor M5, and various drive mechanisms for driving other parts of the apparatus. These operations are all controlled by the controller 10.

  In this embodiment, the toner image is formed by a wet development method in which a toner image is formed using a liquid developer. Therefore, the secondary transfer roller 4 having a grip portion is used so that a sufficient transfer pressure can be applied to the transfer material S while preventing the transfer material S from sticking to the intermediate transfer belt 31. Hereinafter, the structure of the secondary transfer roller 4 will be described in detail with reference to FIGS. 1 and 3 to 5.

  FIG. 3 is a perspective view showing the overall configuration of the secondary transfer roller. FIG. 4 is a view showing an opening / closing mechanism of the gripping portion. As shown in FIGS. 1 and 3, the secondary transfer roller 4 has a roller base 42 provided with a recess 41 formed by cutting out a part of the outer peripheral surface of a cylinder. The roller base material 42 is provided with a rotating shaft 421 extending in a direction orthogonal to the paper surface of FIG. The rotation shaft 421 is provided so as to be rotatable about an axis 4211 with respect to the support arm 40 pivotally supported by an apparatus housing (not shown). The support arm 40 is swingable about the support shaft 401 with respect to the apparatus housing, and is urged counterclockwise in FIG. 1 by urging means (not shown). Therefore, the secondary transfer roller 4 is urged in the direction of the arrow α and is pressed against the intermediate transfer belt 31 wound around the belt drive roller 32. As a result, the secondary transfer roller 4 is pressed against the intermediate transfer belt 31 with a predetermined load (for example, 60 kgf).

  Further, side plates 422 and 422 are attached to both ends of the rotating shaft 421, respectively. More specifically, each of these side plates 422 and 422 has a shape in which a notch 422a is provided on a disk-shaped metal plate. As shown in FIG. 3, the notches 422a and 422a are attached to the rotating shaft 421 while facing each other and separated by a distance slightly longer than the width of the elastic sheet. In this way, the roller base material 42 is formed which has a drum shape as a whole but has a recess 41 extending in parallel or substantially in parallel with the rotation shaft 421 on a part of the outer peripheral surface thereof.

  At both ends of the secondary transfer roller 4, support members 46 are attached to the outer surfaces of the side plates 422 so that they can rotate integrally with the roller base material 42. Further, the support member 46 is formed with a planar region 461 corresponding to the recess 41. The transfer roller side contact member 47 is attached to the flat area 461, respectively. In the abutting member 47, the base part 471 is attached to the support member 46, and the abutting part 472 extends from the base part 471 in the normal direction of the planar region 461, and the distal end portion of the abutting part 472 Extends to the opening side end of the recess 41. That is, when the contact member 47 is viewed from the direction of the rotation shaft 421, the contact member 47 closes the recess 41, and the peripheral end of the contact portion 472 is the peripheral surface of the secondary transfer roller 4 (elastic layer 43. The contact member 47 is provided so as to partially overlap with the contact member 47).

  In addition, bearings 322 (see FIG. 1) that are coaxial with the drive roller 32 and rotatable independently of the drive roller 32 are provided at both ends of the drive roller 32 around which the intermediate transfer belt 31 is wound. When the contact member 47 of the secondary transfer roller 4 faces the drive roller 32 side, the outer peripheral surface of the contact member 47 and the outer peripheral surface of the bearing 322 are in contact with each other.

  Further, an elastic sheet formed of an elastic material such as rubber or resin is wound around the outer peripheral surface of the roller base material 42, that is, the surface region excluding the region corresponding to the inside of the recess 41 on the surface of the metal plate. An elastic layer 43 is formed by the sheet. In this embodiment, the elastic sheet is not bonded to the secondary transfer roller 4 and can be exchanged in order to cope with deterioration over time such as wear and scratches on the elastic sheet (elastic layer 43). . More specifically, one end 431 of the elastic sheet is fixed to the side surface of the recess 41 by a pressing plate (not shown), while a plate 491 is attached to the other end 432 of the elastic sheet, The elastic sheet is stretched on the peripheral surface of the secondary transfer roller 4 without slack by engaging the plate 491 with the sheet stretcher 49 fixed to the bottom of the recess 41.

In this embodiment, the opening length (opening width) W41 of the recess 41 along the rotation direction D4 of the roller base material 42 is about 105 mm. When the elastic layer 43 formed in the region excluding the concave portion 41 on the outer peripheral surface of the secondary transfer roller 4 is in a position facing the intermediate transfer belt 31, the elastic layer 43 is pressed against the intermediate transfer belt 31 and the transfer nip NP. Is formed. The length (transfer nip width) Wnp of the transfer nip NP along the rotation direction D4 of the roller base material 42 is about 11 mm,
(Opening width W41 of the recess 41)> (transfer nip width Wnp at the transfer nip NP)
Have the relationship. Therefore, when the concave portion 41 of the secondary transfer roller 4 faces the intermediate transfer belt 31, the transfer nip temporarily disappears.

  The length of the elastic layer 43 along the rotation direction D4 of the roller base material 42 is set to about 495 mm, and this is the largest size of the transfer material S that can be used in the apparatus 1 is wound. It is something that can be done. That is, the length of the elastic layer 43 is determined to be longer than the length of the usable transfer material S that has the maximum length along the rotation direction D4 of the roller base material 42.

  A grip 44 for gripping the transfer material S is disposed inside the recess 41. The gripping portion 44 includes a gripper support member 441 erected on the outer peripheral surface of the roller base 42 from the inner bottom portion of the recess 41, and a gripper member 442 that is supported so as to be able to come into contact with and separate from the distal end portion of the gripper support member 441. And have. By the operation of the opening / closing mechanism 45 described below, the leading end of the gripper member 442 moves back and forth in the radial direction of the secondary transfer roller 4 and is separated from the leading end of the gripper support member 441 to prepare for gripping the transfer material S. While the gripping and releasing are performed, the transfer material S is gripped by the leading end of the gripper member 442 moving to the leading end of the gripper support member 441.

  As shown in FIGS. 3 and 4, the gripper member 442 is attached to a support shaft 451 of a crank arm 452 configured to be rotatable about a support shaft 451. A cam follower 453 is provided at the tip of the crank arm 452. Although the illustration of the urging member is omitted, the gripper member 442 is urged in a direction (a counterclockwise direction centering on the support shaft 451 in FIG. 4) in which a tip end portion thereof abuts on the gripper support member 441. ing. That is, in a state where no external force is applied, the grip portion 44 is maintained in a closed state. The support shaft 451, the crank arm 452, the cam follower 453, and the like constitute an open / close mechanism 45 integrally.

  On the other hand, a cam member 50 is fixed to the inner side surface of the apparatus housing (not shown) at positions near the axial ends of the secondary transfer roller 4 and the drive roller 32. The outer peripheral surface 500 of the cam member 50 is generally along a circular arc 50a having a radius R50 centered on the rotation center 4211 of the secondary transfer roller 4, but the projecting portions 501 and 502 that partially protrude in the outer peripheral direction. It has the provided shape. The outer peripheral surface of the cam member 50 having such an outer peripheral shape and the outer peripheral surface of the cam follower 453 provided in the opening / closing mechanism 45 are intermittently brought into contact with the rotation of the secondary transfer roller 4. As the cam follower 453 moves following the outer peripheral surface shape of the cam member 50, the crank arm 452 rotates, and the tip of the gripper member 442 opens and closes with respect to the gripper support member 441. That is, in this embodiment, the grip portion 44 automatically opens and closes according to the rotational phase of the secondary transfer roller 4.

  5 and 6 are diagrams illustrating the relationship between the rotation phase of the secondary transfer roller and the open / close state of the gripping portion. 5 and 6 schematically show changes in the open / closed state of the gripping portion 44 due to the rotation of the secondary transfer roller 4 and the state of gripping / release of the transfer material S associated therewith. In FIGS. 5 and 6, in order to clearly show the gripping mechanism, portions that are not related to the operation of the gripping portion, such as the contact member 47 and the sheet stretching portion 49, are omitted. As shown in FIG. 4, when the concave portion 41 of the secondary transfer roller 4 is at a position far away from the secondary transfer position TR2, the cam follower 453 is separated from the cam member 50, and the grip portion 44 is not shown. The closed state is maintained by the action of the biasing member.

  When the rotation of the secondary transfer roller 4 in the direction D4 proceeds, as shown in FIG. 5A, the recess 41 approaches the secondary transfer position TR2, and the cam follower 453 is formed on the outer peripheral surface 500 of the cam member 50. Start to abut. As the rotation further proceeds, as shown in FIG. 5B, the cam follower 453 rides on the first protrusion 501 of the outer peripheral surface 500 of the cam member 50, whereby the crank arm 452 rotates about the support shaft 451. The leading end of the gripper member 442 starts to be separated from the gripper support member 441. In the actual image forming operation, the gate roller 51 starts to be driven according to the rotation of the secondary transfer roller 4, and the transfer material S is conveyed toward the secondary transfer position TR2. Reference symbol Sh indicates the leading end of the transfer material S in the transfer material conveyance direction.

  As shown in FIG. 5C, when the rotation further proceeds and the concave portion 41 faces the secondary transfer position TR2, the nip is temporarily eliminated. The holding part 44 opens further and receives the leading end part Sh of the transfer material S conveyed by the gate roller 51. That is, the transfer material front end portion Sh is inserted between the opened gripper member 442 and the gripper support member 441. At this time, by causing the transfer material front end portion Sh to abut against the gripper member 442, the positional relationship between the rotational phase of the secondary transfer roller 4 and the transfer material front end portion Sh can be determined with high accuracy and reproducibility. it can. Further, the skew of the transfer material S can be corrected.

  After this state, the outer peripheral surface 500 of the cam member 50 has a shape that gradually recedes. For this reason, as the secondary transfer roller 4 further rotates, the opening of the grip portion 44 becomes smaller. Then, finally, as shown in FIG. 5D, the transfer material S is completely closed and the gripping of the transfer material S is completed. In this way, the transfer material S gripping the leading end portion Sh is fed to the secondary transfer position TR2.

  Subsequently, as shown in FIG. 6A, the recess 41 passes the secondary transfer position TR2, and the elastic layer 43 of the secondary transfer roller 4 comes into contact with the intermediate transfer belt 31 via the transfer material S. . That is, the transfer material S is sandwiched in the nip NP between the elastic layer 43 of the secondary transfer roller 4 and the intermediate transfer belt 31. At least until the transfer material front end portion Sh has passed through the nip NP, the gripping portion 44 continues to hold the transfer material front end portion Sh. This prevents the transfer material S from sticking to the intermediate transfer belt 31.

  At this time, that is, when the elastic layer 43 of the secondary transfer roller 4 comes into contact with the intermediate transfer belt 31 via the transfer material S and the transfer nip NP starts to be formed, the cutout portion 911 of the photosensor cam 91 is exposed to the photo. It is assumed that the positional relationship between the photo sensor cam 91 and the photo sensor 92 is set so as to pass the detection position by the sensor 92.

  When the rotation further proceeds, the cam follower 453 comes into contact with the second protrusion 502 on the outer periphery of the cam member 50 as shown in FIG. When the cam follower 453 rides on the protrusion 502, the grip 44 is opened again. Thus, after the transfer material front end Sh is released from the grip 44 as shown in FIG. 6C, the contact between the cam follower 453 and the cam member 50 is completed as shown in FIG. Part 44 is closed. The released transfer material S is fed rearward while being urged toward the secondary transfer roller by the transport mechanism 6 and the air blowing unit 8 (see FIG. 1), and therefore falls down toward the intermediate transfer belt 31. There is no.

  Thus, in this embodiment, as the secondary transfer roller 4 rotates, the contact state between the cam follower 453 on the secondary transfer roller 4 side and the cam member 50 on the apparatus housing side changes, and thereby the gripping portion 44 is opened and closed, and the transfer material S is gripped and released.

  Next, the posture control of the transfer material S in this embodiment will be described. As described above, in this embodiment, the posture of the transfer material S is controlled by blowing an airflow from the blower unit 8 to the transfer material S that has passed through the transfer nip NP. Hereinafter, the operation of the blower unit 8 will be described in more detail.

  FIG. 7 is a view showing a state of attitude control by the blower unit. FIG. 8 is a view of the secondary transfer roller and the air blowing unit as viewed from above. The blower unit 8 includes, for example, blower fans 81 and 81 serving as an air flow generation source, and housing parts 82 and 82 connected to the blower fan 81 and having an opening 83 at the other end. The airflow generated by the blower fan 81 passes through the inside of the housing 82 and blows out from the opening 83 and blows to the peripheral surface of the secondary transfer roller 4. More precisely, it is sent from the transfer nip NP along with the rotation of the secondary transfer roller 4 and sprayed onto the image transfer surface of the transfer material S conveyed along the peripheral surface of the secondary transfer roller 4. In this embodiment, two sets of the blower fan 81 and the casing 82 are arranged in the direction of the rotation axis 4211 of the secondary transfer roller 4 so that the airflow is uniform in the axial direction.

  Further, as shown in FIG. 8, the opening width W2 of the opening 83 of the blower unit 8 in the axial direction of the secondary transfer roller 4 has a plurality of grippers arranged in the recess 41 of the secondary transfer roller 4 in the axial direction. Of the members 442, the width W1 between the two gripper members 442a and 442b located on the outermost side in the axial direction is smaller. The width W1 between the gripper members 442a and 442b is set corresponding to the width of the transfer material S, and more specifically, is approximately the same as the width of the transfer material S. For example, for a Japanese Industrial Standard A3 size transfer material, the width W1 between the gripper members 442a and 442b can be set to 300 mm, and the opening width W2 of the opening 83 of the blower unit 8 can be set to about 320 mm. Further, the opening height of the opening 83 and the dimension of the opening 83 in the direction orthogonal to the plane of FIG. 8 can be set to about 15 mm, for example.

Therefore, the airflow blown out from the opening 83 and collided with the peripheral surface of the secondary transfer roller 4 flows smoothly so as to spread toward the outer side in the axial direction of the secondary transfer roller 4. For this reason, it is avoided that the transfer material S flutters due to the turbulence of the airflow. Here, as the blower fan 81, for example, a super silent blower manufactured by Nidec Servo Corporation can be used. Further, the air volume of each of the blower fans 81 and 81 can be set to, for example, 0.84 m ³ / min (wind speed conversion of about 6.3 m / sec).

  As described above, when passing through the transfer nip NP, the grip portion 44 releases the transfer material S and releases the transfer material S. In this embodiment, the transfer nip NP is formed vertically below the rotation shaft 4211 of the secondary transfer roller 4, and the transfer material S is conveyed from the transfer nip NP in the direction of ascending. The transport mechanism 6 transports the transfer material S while adsorbing the upper surface thereof. In such a configuration, the transfer material S that is released from the grip and has a free end at the leading end may hang down from the circumferential surface of the secondary transfer roller 4 due to gravity. In such a case, there is a possibility that the image transferred to the transfer material S is in contact with the blower unit 8 and is distorted, or the transfer material S once peeled off is stuck to the intermediate transfer belt 31 again. Further, the transfer force of the transfer material S obtained by being in close contact with the secondary transfer roller 4 is reduced, so that the transfer material S may stick to the intermediate transfer belt 31 from an intermediate portion in the transfer direction. is there.

  In this embodiment, since the airflow is blown from the blower unit 8 toward the peripheral surface of the secondary transfer roller 4, the transfer material S that has passed through the transfer nip NP is pressed against the peripheral surface of the secondary transfer roller 4. As a result, the transfer material S is prevented from sagging, and contact with the blower unit 8 and other peripheral members can be avoided. Further, since a sufficient conveying force is given by being in close contact with the peripheral surface of the secondary transfer roller 4, the transfer material S is surely sent to the subsequent conveyance mechanism 6 by the rotation of the secondary transfer roller 4.

  FIG. 9 is a diagram showing an operation sequence of the blower unit. In this embodiment, as shown in FIG. 9A, while the leading end portion Sh of the transfer material S passing through the transfer nip NP is gripped by the gripping portion 44, that is, gripping by the gripping portion 44 is released. Before that, the blowing of the airflow from the blower unit 8 is started. In this way, the transfer material S that has passed through the transfer nip NP is released in a state of being pressed against the peripheral surface of the secondary transfer roller 4 by the air current. For this reason, it is prevented that the transfer material S hangs away from the secondary transfer roller 4.

  Specifically, the operation is shown in the timing chart of FIG. As shown in FIG. 9A, the concave portion 41 of the secondary transfer roller 4 passes the secondary transfer position TR2, and the elastic layer 43 on the peripheral surface abuts against the intermediate transfer belt 31 via the transfer material S, thereby transferring the transfer nip. When NP formation starts, a synchronization signal is output from the photosensor 92 (time T11). The time at which the synchronization signal is output is not limited to the transfer nip formation start time, but is preferably the time at which the transfer material S is reliably gripped by the grip portion 44.

  When the synchronization signal is detected, the controller 10 outputs a drive signal for driving the blower fan 81 of the blower unit 8. As a result, the blower unit 8 is activated, and the blowing of airflow from the blower unit 8 toward the secondary transfer roller 4 is started. The air volume gradually increases with the start of fan driving, and reaches a substantially constant value at a certain time T12.

  As the rotation of the secondary transfer roller 4 proceeds, the gripper member 442 of the gripping portion 44 is rotated by the action of the opening / closing mechanism 45 and the cam member 50 and is released from the gripper support member 441, so that the transfer material S is released. (Time T13). Since the gripper member 442 gradually opens as the secondary transfer roller 4 rotates, it is difficult to uniquely specify the time when the transfer material S is released. For example, the gripper member 442 and the gripper support member 441 Can be defined as “the time when the transfer material S is released”.

  If the air current is continuously blown after the transfer material S is released, the posture of the transfer material S can be maintained. On the other hand, if the leading end portion Sh of the transfer material S reaches the transport mechanism 6, the transfer material S is thereafter transported by the transport mechanism 6, so that the transfer material S does not hang down. Therefore, after the transfer material S is transferred from the secondary transfer roller 4 to the transport mechanism 6, the airflow blowing may be weakened or stopped. Therefore, when the arrival of the transfer material S is detected by the sheet detection sensor 612 provided in the first suction unit 61 (time T14), the controller 10 turns off the drive signal to the blower fan 81. As a result, the amount of air blown gradually decreases and finally stops. In order to maintain the posture of the transfer material S along the peripheral surface of the secondary transfer roller 4 more reliably, the blowing may be continued in a state where the air volume is weakened.

  As described above, in this embodiment, the transfer material S that has passed through the transfer nip NP and has been released from the grip portion 44 has a peripheral surface of the secondary transfer roller 4 that is blown by the air blowing unit 8 before being released. Pressed against. For this reason, the transfer material S is separated from the peripheral surface of the secondary transfer roller 4 or hangs down and does not come into contact with the blower unit 8 or the like, while maintaining the posture along the peripheral surface of the secondary transfer roller 4. It will be sent to the transport mechanism 6.

  Note that the transfer material S released from the gripping portion 44 does not sag immediately, but its posture is maintained for a while by the so-called transfer material waist, that is, the ability of the transfer material to retain its shape. In this sense, from the viewpoint of preventing the transfer material from sagging, the airflow may be blown for a certain period after releasing the grip. Therefore, spraying may be started after the release of gripping. This is especially the case when a stiff transfer material is used, such as paper with a relatively large basis weight. The second embodiment of the image forming apparatus according to the present invention described below corresponds to such a concept.

  FIG. 10 is a diagram showing a second embodiment of the image forming apparatus according to the present invention. In this embodiment, as shown in FIG. 10A, the position of the photosensor 92 is different from that of the first embodiment. That is, the positional relationship between the photosensor 92 and the photosensor cam 91 is set so that the synchronization signal is output after the gripping portion 44 is released from the transfer material S that has passed through the transfer nip NP. Accordingly, the operation sequence of the blower unit 8 is changed to that shown in FIG. Except for this point, the other configurations are the same as those of the first embodiment described above. Therefore, here, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIG. 10B, in this embodiment, the gripping of the transfer material S by the gripping portion 44 is released at time T21, and then a synchronization signal is output from the photosensor 92 (time T22). When this synchronization signal is detected, the controller 10 gives a drive signal to the blower fan 81. Thereby, the blowing of the airflow from the blower unit 8 is started. Thereafter, the process is the same as in the first embodiment. When the sheet detection sensor 612 detects that the transfer material S has reached the first suction unit 61 (time T23), the drive signal to the blower fan 81 is stopped. End spraying.

  As described above, even when the airflow is started after the gripping of the transfer material S by the gripping portion 44 is released, the posture of the released transfer material S is controlled as in the first embodiment. It can be conveyed along the peripheral surface of the secondary transfer roller 4. Therefore, similarly to the first embodiment, the transfer material S is separated from the peripheral surface of the secondary transfer roller 4 or hangs down and does not come into contact with the blower unit 8 or the like, and is along the peripheral surface of the secondary transfer roller 4. It is possible to send the sheet to the subsequent transport mechanism 6 while maintaining the posture.

  More preferably, for the time T22 at which spraying is started, the time at which the leading end portion Sh of the transfer material S passes through the position where the airflow from the blower unit 8 is most strongly sprayed (whether it is gripped or released at this time). It's better to be slower than either). In this way, it is possible to prevent the air current from being blown between the transfer material S and the secondary transfer roller 4 to separate them.

  In the apparatus of the first and second embodiments described above, by providing the opening / closing mechanism 45 that rotates in synchronization with the rotation of the secondary transfer roller 4, the apparatus automatically grips according to the rotation phase of the secondary transfer roller 4. The portion 44 is opened and closed to grip and release the transfer material S. For this reason, it is necessary to rotate the secondary transfer roller 4 in order to cause the grip portion 44 to grip the transfer material S. On the other hand, in the third and fourth embodiments of the present invention described below, an open / close mechanism that operates independently of the rotation of the secondary transfer roller 4 is provided so that the transfer can be performed even when the secondary transfer roller 4 is stopped. The material S can be gripped and released. The apparatus configuration of the third and fourth embodiments is the same as that of the first embodiment except for the configuration of the gripping portion and the opening / closing mechanism provided on the secondary transfer roller, and the operation and Since the operation is the same, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

  FIG. 11 is a diagram showing a main part of a third embodiment of the image forming apparatus according to the present invention. More specifically, FIG. 11A is a diagram showing an opening / closing mechanism in the third embodiment, and FIG. 11B is a diagram showing an operation sequence in the third embodiment. As shown in FIG. 11 (a), in the opening / closing mechanism 45a of this embodiment, a crank arm 452 connected to the gripper member 442 of the grip portion 44 and rotatable about the support shaft 451 is an elliptical or eccentric disk. It is driven by a cylindrical rotating cam member 454a and a gripper opening / closing motor 455a that drives the rotating cam member 454a. More specifically, when the cam follower 453 disposed on the crank arm 452 is in contact with the outer peripheral surface of the rotating cam member 454a and the gripper opening / closing motor 455a rotates in response to a control signal from the controller 10, a dotted line As shown, the rotating cam member 454a connected to the motor rotates around the support shaft, and the cam follower 453 moves along the outer peripheral surface thereof. As a result, the crank arm 452 rotates around the support shaft 451 to open and close the grip portion 44.

  The operation sequence of the blower unit 8 in this configuration is as shown in FIG. That is, as in the first embodiment, the controller 10 receives the synchronization signal from the photosensor 92 at time T31 when the transfer material S is gripped by the gripping portion 44, and the controller 10 performs time T32 to time T33. Meanwhile, a drive signal is given to the gripper opening / closing motor 455a. During this time, the grip portion 44 is opened by the operation of the grip portion opening / closing motor 455a, and the grip of the transfer material S is released.

  Further, the controller 10 gives a driving signal for the blower fan 81 to the blower unit 8 almost simultaneously with giving a drive signal to the gripper opening / closing motor 455a. As a result, when the grip portion 44 releases the transfer material S by the operation of the grip portion opening / closing motor 455a, the air current is blown against the transfer material S. Therefore, also in this embodiment, similarly to the first embodiment, it is possible to send the transfer material S to the transport mechanism 6 while maintaining the posture of the transfer material S along the peripheral surface of the secondary transfer roller 4. . The operation after the transfer material S reaches the first suction portion 61 can be the same as in the first embodiment.

  In such a configuration, since the release operation by the gripping unit and the operation of the blower unit 8 are both performed by the drive signal from the controller 10, the timing can be managed more easily and accurately. .

  FIG. 12 is a view showing the main part of a fourth embodiment of the image forming apparatus according to the present invention. As shown in FIG. 12, in this embodiment, the rear end portion of the gripper member 442b provided on the grip portion 44b opposite to the front end portion for gripping the transfer material is extended, and the gripper member 442b is a support shaft. It is freely rotatable around 443b. The opening / closing mechanism 45b includes a spring 451b provided on the rear end side of the gripper member 442b and biasing the gripper member 442b in the closing direction, and a solenoid 452b provided on the front end side of the gripper member 442b. Yes. When the solenoid 452b is actuated according to the control signal from the controller 10, the tip of the gripper member 442b is pushed up against the urging force of the spring 451b, and the gripping part 44b is opened as shown by the dotted line.

  The operation of the blower unit 8 in this configuration is the same as that of the third embodiment except that the drive signal to the solenoid 452b is used instead of the drive signal to the gripper opening / closing motor, and the operation and effects thereof are also the third. It is the same as that of the embodiment.

  As described above, in each of the above embodiments, the secondary transfer roller 4 and the intermediate transfer belt 31 function as the “transfer roller” and the “image carrier belt” of the present invention, respectively. The controller 10 functions as a “control unit” of the present invention. Further, the grip portion 44 functions as a “grip member” of the present invention, while the blower unit 8 functions as an “airflow generation portion” of the present invention. Further, in these embodiments, the photo sensor 92 functions as the “signal output unit” of the present invention, and the transport mechanism 6 functions as the “transport unit” of the present invention. The first suction part 61 functions as a “guide part” of the present invention.

  The present invention is not limited to the above-described embodiment, and various modifications other than those described above can be made without departing from the spirit of the present invention. For example, in each of the above-described embodiments, after the leading end of the transfer material S reaches the transport mechanism 6, the blowing of the air current is weakened or stopped, but the posture of the transfer material S is more reliably controlled. Therefore, for example, the airflow may be continued until the rear end of the transfer material S reaches the transport mechanism 6. Further, the air volume may be changed step by step. Further, in each of the above embodiments, the sheet detection sensor 612 is provided in the first suction unit 61 that is closest to the secondary transfer roller 4 in the transport mechanism 6, but is not limited thereto, for example, the transfer material transport unit 62 or A sheet detection sensor may be provided in the second suction part 63. These sensors can also serve as jam detection sensors that are generally provided on the transport path PT for jam detection.

  Further, as described above, the waist strength varies depending on the type and properties of the transfer material, and the degree of sag after release of gripping also varies. Therefore, the amount of air to be blown may be changed depending on the type and properties of the transfer material.

  Further, for example, in each of the above embodiments, the photo sensor 92 outputs a synchronization signal when the elastic layer 43 on the peripheral surface starts to contact the intermediate transfer belt 31 by the rotation of the secondary transfer roller 4. However, the present invention is not limited to this, and various signals can be used as the “signal” of the present invention as long as the signals are synchronized with the rotation of the secondary transfer roller 4. Among these, in the configuration in which the output timing of the synchronization signal does not coincide with the grip / release timing by the grip portion 44, gripping or release is performed when a predetermined time elapses after the synchronization signal is output (determined by the device configuration). The operating sequence can be planned assuming that

  Further, each of the above embodiments is a so-called liquid development type image forming apparatus using a developer in which toner is dispersed in a liquid carrier, and the effect of the present invention is particularly remarkable. The target is not limited to that. That is, regardless of the development method, as illustrated in FIG. 1, the image carrier belt is brought into contact with the transfer roller having a concave portion on the peripheral surface and provided with a holding member for holding the transfer material in the concave portion. The present invention can be applied to all image forming apparatuses having such a structure.

  2C, 2K, 2M, 2Y ... image forming station, 4 ... secondary transfer roller (transfer roller), 6 ... transport mechanism (transport unit), 8 ... air blow unit (airflow generating unit), 10 ... controller (control unit), DESCRIPTION OF SYMBOLS 21 ... Photosensitive drum, 24 ... Developing unit, 31 ... Intermediate transfer belt (image carrier belt), 44, 44b ... Gripping part (gripping member), 45 ... Opening / closing mechanism, 45a, 45b ... Opening / closing mechanism, 61 ... First Suction part (guide part), 92 ... Photo sensor (signal output part), NP ... Transfer nip, S ... Transfer material

Claims (8)

An image carrier belt carrying an image;
The peripheral surface has a concave portion and rotates around a rotation axis, and a peripheral surface different from the concave portion is in contact with the image carrier belt via the transfer material to form a transfer nip and grip the transfer material, or A transfer roller in which the holding member that releases the transfer material below the virtual horizontal plane that includes the center of the rotation axis and is perpendicular to the vertical direction is disposed in the concave portion;
An airflow generating part that blows an airflow on the transfer material that has passed through the transfer nip; and
An image forming apparatus comprising: a control unit that blows an airflow from the airflow generation unit to the transfer material when the transfer material is released from the gripping member. A guide portion for guiding the transfer material released from the gripping member;
The image forming apparatus according to claim 1, wherein the control unit generates an air flow from the air flow generation unit while the transfer material moves to the guide unit after releasing the transfer material from the gripping member.   The image forming apparatus according to claim 1, wherein the control unit generates an airflow from the airflow generation unit when the transfer material is held by the holding member. A signal output unit that outputs a signal synchronized with the rotation of the transfer roller;
The image forming apparatus according to claim 1, wherein the control unit controls generation of an air flow of the air flow generation unit based on the signal.   The image forming apparatus according to claim 4, wherein the control unit controls release of the transfer material from the gripping member based on the signal output from the signal output unit. A transport unit that transports the transfer material released from the gripping member;
The controller controls the flow rate of the airflow from the airflow generation unit after the transfer unit starts transporting the transfer material, and the airflow generation unit before the transfer material starts to be transported by the transport unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is smaller than an air flow rate from the air flow. Grasping the transfer material with the gripping member disposed in the recess of the transfer roller having a recess on the peripheral surface,
The image carried on the image carrier belt is transferred to the transfer material held by the holding member at a transfer nip formed by the image carrier belt and the transfer roller,
The transfer material onto which the image has been transferred is released from the gripping member below the virtual horizontal plane that includes the rotation center of the transfer roller and is perpendicular to the vertical direction, and the airflow from the airflow generation unit is transferred to the transfer material. An image forming method characterized by spraying on a material. Grasping the transfer material with the gripping member disposed in the recess of the transfer roller having a recess on the peripheral surface,
The image carried on the image carrier belt is transferred to the transfer material held by the holding member at a transfer nip formed by the image carrier belt and the transfer roller,
Blowing an airflow from an airflow generation unit onto the transfer material onto which the image has been transferred,
An image forming method, wherein the transfer material is released from the gripping member below a virtual horizontal plane including a rotation center of the transfer roller and perpendicular to the vertical direction in a state where the airflow is blown.

Images