JP2009046213A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of converging the speed of a rotor when a recording medium enters between the rotor with an image recorded thereon and rotated while holding the recording medium on its peripheral surface and a transfer roller or a press roller rotated while sandwiching the recording medium together with the rotor, to a target speed easily and within a short period of time in comparison with the conventional case. <P>SOLUTION: Distances between the rotating shafts of an intermediate transfer belt 14 and the transfer roller 34 are made different at an axial one end and an axial other end. This can be achieved by abutting a positioning member 32 on a bearing 16 mounted at the axial other end of the transfer roller 34 pressed to the side of the intermediate transfer belt 14 by a compression coil spring 18 and inclining the rotating shaft 34A of the transfer roller 34 to the rotating shaft 30A of a driven roller 20 brought into pressure contact with the transfer roller 34 through the intermediate transfer belt 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  When the recording medium enters the nip between the rotating member such as the image bearing member or intermediate transfer member and the roller such as the transfer roller, the rotating member undergoes a speed fluctuation due to an increase in load torque. Various configurations intended to do this have been proposed (see, for example, Patent Documents 1 to 3).

  In the configuration described in Patent Document 1, the load torque generated in the image carrier when entering the recording medium is reduced by providing a gap between the image carrier and the transfer roller. If the rise of the load torque at the time of entry is steep, a sufficient effect cannot be obtained.

  Further, in the configuration described in Patent Document 2, the recording medium is skewed between the image carrier and the transfer roller so as to enter the recording medium, thereby reducing the load torque generated in the image carrier when the recording medium enters. It is necessary to correct the image in accordance with the skew of the medium, and the image correction control becomes complicated.

Furthermore, in the configuration described in Patent Document 3, the load torque generated in the image carrier when the recording medium enters is reduced by cutting the leading end of the recording medium obliquely, but the leading end of the recording medium is cut obliquely. It's not easy to do.
JP 2002-229349 A Japanese Patent Laid-Open No. 10-153891 Japanese Patent Laid-Open No. 11-231429

  On the other hand, in an ink jet recording type image forming apparatus or the like, an angular velocity of a roller rotating a rotating body such as an intermediate transfer member or a conveyance belt is sensed by an encoder or the like, and the motor is feedback-controlled so as to reach a target speed. . However, in the case of high-speed printing, etc., when the rotating body that has entered the recording medium undergoes significant deceleration in a short time, it takes time to converge to the target speed due to overshoot, etc. Control may not be in time.

  In consideration of the above-mentioned fact, the present invention is arranged between a rotating body that rotates with an image formed or holding a recording medium on the peripheral surface, and a transfer roller or a pressing roller that rotates with the rotating body sandwiching the recording medium. An object of the present invention is to provide an image forming apparatus capable of converging the peripheral speed of a rotating body when a recording medium enters into a target speed more easily and in a shorter time than in the past.

  The image forming apparatus according to claim 1, wherein a rotating body on which an image is formed on a circumferential surface, and the recording medium is rotated together with the rotating body, and the image formed on the circumferential surface of the rotating body is used as a recording medium. A transfer roller for transferring, and a rotation axis distance regulating means for making the distance between the rotation axes of the rotating body and the transfer roller before sandwiching the recording medium different between one end side and the other end side in the axial direction. It is characterized by.

  In the image forming apparatus according to the first aspect, the peripheral surface of the rotating body and the transfer roller rotate with the recording medium interposed therebetween, whereby the image is transferred from the peripheral surface of the rotating body to the recording medium.

  Here, the distance between the rotating shafts of the rotating body and the transfer roller is regulated by the rotating shaft distance regulating means, and at the time before the recording medium is sandwiched, the distance between the rotating shafts of the rotating body and the transfer roller is The axial direction is different between one end side and the other end side. For this reason, a difference occurs in the timing at which the recording medium enters between the one end side and the other end side in the axial direction of the rotating body and the transfer roller. That is, the recording medium gradually enters between the rotating body and the transfer roller from one end side or the other end side in the axial direction to the opposite side. As a result, the rise of the load torque generated in the rotating body when the recording medium enters is moderate as compared with the case where the distance between the rotating shafts of the rotating body and the transfer roller is constant.

  Accordingly, the amount of deceleration with respect to the target peripheral speed of the rotating body at the time of entering the recording medium can be reduced compared with the case where the distance between the rotating shafts is constant, and thus compared with the case where the distance between the rotating shafts is constant, The peripheral speed of the rotating body when entering the recording medium can be converged to the target speed easily and in a short time.

  The image forming apparatus according to claim 2 is the image forming apparatus according to claim 1, further comprising a bearing that supports the transfer roller so as to be able to contact and separate from the rotating body, and the rotation. The inter-axis distance regulating means is disposed on the rotating body side from the biasing means for biasing the transfer roller toward the rotating body, on one end side or both end sides in the axial direction of the transfer roller, and on the rotating shaft of the transfer roller, A positioning member that presses the bearing against the urging unit and tilts the rotation shaft of the transfer roller with respect to the rotation shaft of the rotating body.

  In the image forming apparatus according to the second aspect, the transfer roller supported by the bearing so as to be able to contact and separate from the rotating body is urged toward the rotating body by the urging means. A positioning member is disposed on one end side or both end sides in the axial direction of the transfer roller and on the rotating body side of the rotation shaft of the transfer roller. Is inclined with respect to the rotation axis of the rotating body. Thereby, the distance between the rotating shafts of the rotating body and the transfer roller before sandwiching the recording medium is different between the one end side in the axial direction and the other end side.

  Here, when the recording medium is sandwiched between the rotating body and the transfer roller, the transfer roller is separated from the rotating body against the biasing force of the biasing means due to the thickness of the recording medium, The distance between the rotation axes with the transfer roller is uniform. Therefore, the transfer pressure between the rotating body and the transfer roller at the time of transfer is uniform from one end side to the other end side in the axial direction, thereby ensuring transfer performance.

  The image forming apparatus according to claim 3 is the image forming apparatus according to claim 1, wherein the distance between the rotation shafts is a rotation shaft between the rotating body and the transfer roller before the recording medium is sandwiched therebetween. The distance between the axial direction one end side and the other end side can be adjusted, and the drive means for causing the rotation axis distance regulating means to perform the adjusting operation, and the thickness of the recording medium increase. And a control means for controlling the drive means so that the difference amount increases with time.

  4. The image forming apparatus according to claim 3, wherein the difference between the rotational axis distances between the rotating body and the transfer roller before the recording medium is sandwiched between the one axial end side and the other axial end side is the rotational axis distance regulating means. Thus, the difference amount is increased or decreased by driving the inter-rotary axis distance regulating means by the driving means.

  Here, the drive means is controlled by the control means so that the difference amount increases as the thickness of the recording medium increases. As a result, the gap amount or the nip width and pressure between the rotator and the transfer roller can be set to values corresponding to the thickness of the recording medium, and the peripheral speed of the rotator when the recording medium enters can be further stabilized. It becomes possible.

  The image forming apparatus according to claim 4 is the image forming apparatus according to claim 3, wherein the image forming apparatus includes a bearing that supports the transfer roller so as to be in contact with and away from the rotating body. The inter-axis distance regulating means is disposed on the rotating body side from the biasing means for biasing the transfer roller toward the rotating body, on one end side or both end sides in the axial direction of the transfer roller, and on the rotating shaft of the transfer roller. The bearing is pressed by the urging unit, and the rotation shaft of the transfer roller is inclined with respect to the rotation shaft of the rotating body and is rotated by the driving unit, whereby the rotation shaft of the transfer roller is rotated. And a rotating cam that changes an inclination angle with respect to the rotation axis of the rotating body.

  In the image forming apparatus according to the fourth aspect, the transfer roller supported so as to be able to come into contact with and separate from the rotating body by the bearing is biased toward the rotating body by the biasing means. A rotating cam is disposed on one end side or both end sides in the axial direction of the transfer roller and on the rotating body side of the rotating shaft of the transfer roller. Is inclined with respect to the rotation axis of the rotating body. Thereby, the distance between the rotating shafts of the rotating body and the transfer roller before sandwiching the recording medium is different between the one end side in the axial direction and the other end side.

  Here, the rotation cam changes the inclination angle of the transfer roller with respect to the rotation axis of the rotating body by being rotated by the driving means. Thereby, the difference amount between the rotation axis and the transfer roller between the rotation axis and the one end side in the axial direction is adjusted.

  Further, the driving means is controlled by the control means so that the difference amount increases as the thickness of the recording medium increases. This makes it possible to set the gap amount between the rotator and the transfer roller or the nip width and pressure to an appropriate value according to the thickness of the recording medium. Can be further stabilized.

  The image forming apparatus according to claim 5, wherein a rotating body that holds and conveys a recording medium on a peripheral surface, an image forming unit that forms an image on the recording medium that is conveyed by the rotating body, and the recording medium The distance between the rotating shafts of the pressing roller, which presses the recording medium against the rotating body and presses the recording medium against the rotating body, and the rotating body and the pressing roller before sandwiching the recording medium is It is characterized by having a distance control means between the rotation axes which is different between one end side and the other end side in the direction.

  In the image forming apparatus according to the fifth aspect, the recording medium is pressed against the peripheral surface of the rotating body by rotating the peripheral surface of the rotating body and the pressing roller with the recording medium interposed therebetween. The rotating body holds and conveys the recording medium on its peripheral surface, and the image forming unit forms an image on the recording medium conveyed by the rotating body.

  Here, the distance between the rotating shafts of the rotating body and the pressing roller is regulated by the rotating shaft distance regulating means, and at the time before the recording medium is sandwiched, the distance between the rotating shafts of the rotating body and the pressing roller is The axial direction is different between one end side and the other end side. For this reason, a difference occurs in the timing at which the recording medium enters between the one end side and the other end side in the axial direction of the rotating body and the pressing roller. That is, the recording medium gradually enters between the rotating body and the pressing roller from one axial end side or the other end side to the opposite side. As a result, the rise of the load torque generated in the rotating body when the recording medium enters is moderate as compared with the case where the distance between the rotating shafts of the rotating body and the pressing roller is constant.

  Accordingly, the amount of deceleration with respect to the target peripheral speed of the rotating body at the time of entering the recording medium can be reduced compared with the case where the distance between the rotating shafts is constant, and thus compared with the case where the distance between the rotating shafts is constant, The peripheral speed of the rotating body when the recording medium enters can be converged to the target speed easily and in a short time.

  The image forming apparatus according to claim 6 is the image forming apparatus according to claim 5, wherein the distance between the rotation shafts restricting means biases the pressing roller toward the rotating body, and One end side or both end sides of the pressing roller in the axial direction and on the rotating body side of the rotating shaft of the pressing roller, abuts on the rotating shaft of the pressing roller or a bearing supporting the rotating shaft, and the rotating shaft of the pressing roller And a positioning member that tilts the rotating body with respect to the rotation axis of the rotating body.

  In the image forming apparatus according to the sixth aspect, the pressing roller supported by the bearing so as to be able to contact and separate from the rotating body is urged toward the rotating body by the urging means. A positioning member on which the bearing is pressed by the urging means is disposed at one or both ends in the axial direction of the pressing roller and on the rotating body side of the rotating shaft of the pressing roller, and the rotating shaft of the pressing roller is arranged by the positioning member. Is inclined with respect to the rotation axis of the rotating body. Thereby, the distance between the rotating shafts of the rotating body and the pressing roller before sandwiching the recording medium is different between the one end side in the axial direction and the other end side.

  Here, when the recording medium is sandwiched between the rotating body and the pressing roller, the pressing roller is separated from the rotating body against the biasing force of the biasing means due to the thickness of the recording medium. The distance between the rotating shafts with the pressing roller is uniform. Therefore, the transfer pressure between the rotating body and the pressing roller during transfer is uniform from one end side to the other end side in the axial direction, thereby ensuring pressing performance.

  The image forming apparatus according to claim 7 is the image forming apparatus according to claim 5, wherein the distance between the rotation shafts is a rotation shaft between the rotating body and the pressing roller before the recording medium is sandwiched therebetween. The distance between the axial direction one end side and the other end side can be adjusted, and the drive means for causing the rotation axis distance regulating means to perform the adjusting operation, and the thickness of the recording medium increase. And a control means for controlling the drive means so that the difference amount increases with time.

  In the image forming apparatus according to claim 7, the difference between the rotational axis distances between the rotating body and the pressing roller before the recording medium is sandwiched between the one end side and the other end side in the axial direction is the distance between the rotating shaft control means. Thus, the difference amount is increased or decreased by driving the inter-rotary axis distance regulating means by the driving means.

  Here, the drive means is controlled by the control means so that the difference amount increases as the thickness of the recording medium increases. This makes it possible to set the gap amount between the rotating body and the pressure roller or the nip width and pressure to an appropriate value according to the thickness of the recording medium. The peripheral speed can be further stabilized.

  The image forming apparatus according to claim 8 is the image forming apparatus according to claim 7, wherein the image forming apparatus includes a bearing that supports the pressing roller so as to be in contact with and away from the rotating body. The inter-axis distance restricting means is disposed on the rotating body side from the biasing means for biasing the pressing roller toward the rotating body, on one end side or both end sides in the axial direction of the pressing roller, and on the rotating shaft of the pressing roller. The bearing is pressed by the urging means, the rotation shaft of the pressing roller is inclined with respect to the rotation shaft of the rotating body, and rotated by the driving means, whereby the rotation shaft of the pressing roller is rotated. And a rotating cam that changes an inclination angle with respect to the rotation axis of the rotating body.

  In the image forming apparatus according to the eighth aspect, the pressing roller supported by the bearing so as to be able to contact and separate from the rotating body is urged toward the rotating body by the urging means. A rotating cam is disposed on one end side or both end sides in the axial direction of the pressing roller and on the rotating body side of the rotating shaft of the pressing roller so that the bearing is pressed by the urging means, and the rotating cam rotates the rotating shaft of the pressing roller. Is inclined with respect to the rotation axis of the rotating body. Thereby, the distance between the rotating shafts of the rotating body and the pressing roller before sandwiching the recording medium is different between the one end side in the axial direction and the other end side.

  Here, the rotating cam changes the inclination angle of the pressing roller with respect to the rotating shaft of the rotating body by being rotated by the driving means. Thereby, the difference amount of the distance between the rotating shafts of the rotating body and the pressing roller between the one end side and the other end side in the axial direction is adjusted.

  Further, the driving means is controlled by the control means so that the difference amount increases as the thickness of the recording medium increases. This makes it possible to set the gap amount between the rotating body and the pressure roller or the nip width and pressure to an appropriate value according to the thickness of the recording medium. The peripheral speed can be further stabilized.

  As described above, according to the present invention, the rotating body on which an image is formed or the recording medium is held by the peripheral surface and rotating, and the transfer roller or the pressing roller that rotates with the recording medium sandwiched between the rotating body. Thus, it is possible to provide an image forming apparatus capable of converging the peripheral speed of the rotating body when the recording medium enters into the target speed in a shorter time than in the conventional case.

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

  FIG. 1 shows an ink jet recording apparatus 10 according to a first embodiment of the present invention. The ink jet recording apparatus 10 includes ink jet recording heads (image forming means) 12Y, 12M, 12C, and 12K, and an intermediate transfer belt 14 stretched by a plurality of rollers such as a driving roller 22.

  The intermediate transfer belt 14 is stretched in a polygonal shape by a driving roller 22 and a driven roller 24 disposed substantially horizontally, and driven rollers 26, 27, 30, and 32 disposed below them. Here, the horizontal portion 14H stretched by the driving roller 22 and the driven roller 24 of the intermediate transfer belt 14 extends substantially horizontally in the width direction and the rotation direction, and the ink jet recording heads 12Y, 12M, 12C, 12K. Opposite to.

  The intermediate transfer belt 14 is rotated by the driving roller 22, and the driven rollers 24, 26, 27, 30, and 32 are rotated by following the rotating intermediate transfer belt 14.

  The driven roller 30 disposed at the bottom of the plurality of rollers that stretch the intermediate transfer belt 14 constitutes a transfer roller pair 36 together with the transfer roller 34. The transfer roller pair 36 is disposed in the transport path of the paper P as a recording medium. A transport roller pair 40 is disposed on the upstream side of the transfer roller pair 36 in the transport direction, and the transfer roller pair 36 is transported in the transport direction. A fixing roller pair 42 is disposed on the downstream side.

  The pair of transport rollers 40 includes a driven roller 52 and a drive roller 54 that face each other in the vertical direction across the transport path of the paper P. The fixing roller pair 42 includes a driven roller 56 and a driving roller 58 that face each other in the vertical direction across the conveyance path of the paper P. The drive roller 58 is a heating roller having a heat source such as a heater lamp.

  Here, the rotation shafts of the drive rollers 22, 54, 58 are connected to a motor (not shown) through a gear train (not shown), and the drive rollers 22, 54, 58 are driven by the motor. .

  As shown in FIG. 2B, the transfer roller 34 and the driven roller 30 constituting the transfer roller pair 36 sandwich the paper P and the intermediate transfer belt 14 (not shown) in a substantially parallel state, and the intermediate transfer belt 14 The ink image is transferred to the paper P. As shown in FIGS. 2A and 2B, both ends of the transfer roller 34 in the axial direction are provided with bearings 16 on side plates (not shown) erected on both ends in the axial direction of the rotation shaft 34 </ b> A of the transfer roller 34. It is supported. Here, the bearing 16 is attached to the side plate so as to be slidable in the radial direction of the driven roller 30 and in the direction in which the driven roller 30 is in contact with and separated from the driven roller 30 (the rotation shaft 30A).

  Further, a spring mounting portion 20 is provided on the opposite side of the driven roller 30 of the bearing 16, and a compression coil spring (elastic member) 28 as an urging means is interposed between the bearing 16 and the spring mounting portion 20. It is sandwiched in an elastically compressed state. That is, the bearing 16 and the transfer roller 34 are urged toward the driven roller 30 by the compression coil spring 28.

  Here, one axial end portion of the roller portion 34 </ b> B of the transfer roller 34 is in pressure contact with one axial end portion of the roller portion 30 </ b> B of the driven roller 30 via the intermediate transfer belt 14. On the other hand, the positioning member 32 is disposed on the other axial end side of the rotating shaft 34A and between the bearing 16 and the rotating shaft 30A, and the bearing 16 is pressed against the positioning member 32 by the compression coil spring 28. The positioning member 32 positions the bearing 16 on the other end side in the axial direction on the side farther from the driven roller 30 than the bearing 16 on the one end side in the axial direction.

  That is, as shown in FIGS. 3A to 3C, the rotation shaft 34A of the transfer roller 34 is inclined toward the side away from the one end side in the axial direction to the other end side with respect to the rotation shaft 30A of the driven roller 30. The distance L between the rotation axes of the intermediate transfer belt 14 (the driven roller 30) and the transfer roller 34 is different between the one end side and the other end side in the axial direction, and from the one end side in the axial direction to the other end side. It gradually expands toward

  The gap G on the other end side in the axial direction between the intermediate transfer belt 14 and the transfer roller 34 needs to be smaller than the thickness of the paper P. If this condition is satisfied, the intermediate transfer belt 14 and the transfer roller The entire width of the sheet P sandwiched between the intermediate transfer belt 14 and the intermediate transfer belt 14 and the transfer roller 34 is pressed from these.

  Next, the operation in this embodiment will be described.

  The paper P is transported to the transport roller pair 40 by a transport roller (not shown) disposed on the upstream side of the transport roller pair 40 in the transport direction, and enters the nip portion of the transport roller pair 40 that is pressed against each other. Then, the paper P is conveyed downstream by the frictional force generated between the driving roller 54 and the driven roller 52 and enters the nip portion of the transfer roller pair 36.

  On the other hand, the ink jet recording heads 12Y, 12M, 12C, and 12K start discharging ink droplets to the horizontal portion 14H of the intermediate transfer belt 14 before the leading edge of the paper P enters the nip portion of the pair of transfer rollers 36. An ink image is formed on the intermediate transfer belt 14.

  At the nip portion of the transfer roller pair 36, the paper P and the intermediate transfer belt 14 are pressurized by the transfer roller 34 and the driven roller 30, and the ink image on the intermediate transfer belt 14 is transferred to the paper P.

  The sheet P to which the ink image has been transferred is conveyed downstream by the frictional force generated between the transfer roller 34 and the intermediate transfer belt 14 and enters the nip portion of the fixing roller pair 42. At the nip portion of the fixing roller pair 42, the paper P to which the ink image has been transferred is heated under pressure by the driving roller 58 and the driven roller 56, whereby the ink image is fixed on the paper P. The paper P on which the ink image is fixed is conveyed downstream by the frictional force generated between the driving roller 58 and the driven roller 56, and is finally discharged out of the apparatus.

  In the following description, for the sake of convenience, the presence of the intermediate transfer belt 14 is omitted, but actually, the sheet P and the transfer roller 34 abut on the intermediate transfer belt 14 instead of the driven roller 30.

  As shown in FIGS. 4A and 4B, when the leading edge of the paper P enters between the rollers of the transfer roller pair 36, first, the driven roller 30 and the transfer roller 34 are upstream of the minimum gap point on the conveyance side. Collide with. After the collision, the leading edge of the paper P is sandwiched between the driven roller 30 and the transfer roller 34 to generate a (transient) load torque T (to exert a braking action) on the driven roller 30 and the transfer roller 34, and the driven roller 30. In addition, the peripheral speed of the transfer roller 34 is reduced (see the graph of FIG. 5).

  Note that X = 0 on the horizontal axis of the graph of FIG. 5 indicates a position on a straight line connecting the rotation axes of the driven roller 30 and the transfer roller 34, that is, the center position of the nip portion. The dotted line in the graph indicates the load torque T when the left-right difference in the distance between the rotation axes of the transfer roller 34 and the driven roller 30 is zero, that is, when the rotation axes of the transfer roller 34 and the driven roller 30 are parallel. The one-dot chain line and the solid line in the graph indicate the load torque T when the left-right difference in the distance between the rotation axes of the transfer roller 34 and the driven roller 30 is increased from zero.

  Here, as shown in FIGS. 6A and 6B, when the leading end of the sheet P collides with one end side in the axial direction of the driven roller 30 and the transfer roller 34 (see FIG. 6A), it On the other end side in the axial direction (see FIG. 6B) where the distance between the rotation axes (the gap between the rollers) is large, the leading edge of the paper P has not yet collided.

  That is, the distance between the rotation axes of the driven roller 30 and the transfer roller 34 (the inter-roller gap) gradually increases from one end side in the axial direction to the other end side. The collision with the transfer roller 34 occurs such that the driven roller 30 and the transfer roller 34 start from one end side in the axial direction and end at the other end side.

  Accordingly, it is possible to obtain the same effect as when the paper P is skewed with respect to the traveling direction and rushed between the driven roller 30 and the transfer roller 34. As shown in the graph of FIG. The rise of the load torque T generated at the time of the driven roller 30 and the transfer roller 34 can be made slower than when the distance between the rotation axes of the driven roller 30 (intermediate transfer belt 14) and the transfer roller 34 is constant.

  Therefore, the amount of deceleration with respect to the target peripheral speed of the intermediate transfer belt 14 when the paper P enters can be reduced as compared with the case where the distance between the rotation axes of the intermediate transfer belt 14 and the transfer roller 34 is made constant. Compared to this case, the peripheral speed of the intermediate transfer belt 14 when entering the paper P can be converged to the target speed in a short time.

  On the other hand, when the distance between the rotation axes of the intermediate transfer belt 14 and the transfer roller 34 is made uniform, the rising of the load torque T when the sheet P enters, as shown in the graph of FIG. As a result, the amount of deceleration of the intermediate transfer belt 14 when the sheet P enters is larger than that of the present embodiment.

  On the other hand, in the present embodiment, the rise of the load torque T at the time of entering the paper P depends on the setting of the difference amount between the one end side and the other end side in the axial direction of the gap between the intermediate transfer belt 14 and the transfer roller 34. Can be gradually reduced to an allowable level, and the amount of deceleration with respect to the target peripheral speed of the intermediate transfer belt 14 when the paper P enters can be reduced to the allowable level, so that the peripheral speed of the intermediate transfer belt 14 when the paper P enters is reduced. The target speed can be converged within the allowable time.

  Therefore, it is possible to suppress image quality deterioration such as color misregistration and color unevenness caused by fluctuations in the speed of the intermediate transfer belt 14 when the nip portion of the paper P enters, as compared with the comparative example. Further, in the present embodiment, the above-described effects can be obtained without performing complicated control such as image correction control in accordance with the skew of the paper P. Therefore, compared with the comparative example and the conventional example, The configuration can be simplified.

  In this embodiment, when the paper P is sandwiched between the intermediate transfer belt 14 and the transfer roller 34, the transfer roller 34 resists the urging force of the compression coil spring 28 due to the thickness of the paper P. Separated from the intermediate transfer belt 14 side, the distance between the rotation axes of the intermediate transfer belt 14 and the transfer roller 34 becomes uniform. Therefore, the transfer pressure between the intermediate transfer belt 14 and the transfer roller 34 at the time of transfer is uniform from one end side to the other end side in the axial direction, thereby ensuring transfer performance.

  In this embodiment, the gap between the intermediate transfer belt 14 and the transfer roller 34 is different between the one end side and the other end side in the axial direction. However, as shown in FIGS. The gap between the transfer belt 14 and the transfer roller 34 is uniform from one end side in the axial direction to the other end side, and the nip amount (width) between the intermediate transfer belt 14 and the transfer roller 34 is set to one end side in the axial direction. It is also possible to obtain the same effect as in the present embodiment by making it different from the other end side.

  In this embodiment, the gap is formed only on the other axial end side of the intermediate transfer belt 14 and the transfer roller 34 by installing the positioning member 32 only on the other axial end side of the transfer roller 34. Even if gaps having different sizes are formed on both ends of the intermediate transfer belt 14 and the transfer roller 34 in the axial direction by installing positioning members 32 having different protrusion amounts toward the 16 side on both ends in the axial direction of the transfer roller 34. Good.

  Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st Embodiment, and description is abbreviate | omitted.

  As shown in FIG. 9, in this embodiment, a rotating cam 38 is provided instead of the positioning member 32. The rotary cam 38 is an eccentric cam that is rotatably supported around a rotary shaft 38 </ b> A extending along the axial direction of the driven roller 30, and the bearing 16 is pressed against the peripheral surface by a compression coil spring 28. ing.

  Here, the rotation shaft 38 </ b> A is an output shaft of a motor (driving means) 44, and is rotated by the motor 44 to bring the bearing 16 into and out of contact with the rotation shaft 30 </ b> A of the driven roller 30. The motor 44 is controlled by a control unit (control means) 46. Information such as the thickness of the paper P input from an external device such as a personal computer or an operation panel 48 (hereinafter referred to as the operation panel 48 or the like) is transmitted to the control unit 46.

  When the thickness of the paper P is less than a predetermined value T1 (for example, in the case of thin paper), a motor is used to set the distance between the rotation axes of the intermediate transfer belt 14 and the transfer roller 34 at the other axial end to the predetermined value L1. The rotation phase of 44 is adjusted. When the thickness of the paper P is equal to or greater than the predetermined value T1 and smaller than the predetermined value T2 (for example, when the thickness of the paper P is a standard size (plain paper)), the axial direction between the intermediate transfer belt 14 and the transfer roller 34 The rotation phase of the motor 44 is adjusted so that the distance between the rotation axes on the other end side is a predetermined value L2 (> L1). Further, when the thickness of the paper P is equal to or greater than the predetermined value T2 (for example, in the case of thick paper), the distance between the rotation axes on the other axial end side of the intermediate transfer belt 14 and the transfer roller 34 is set to a predetermined value L3 (> L2), the rotational phase of the motor 44 is adjusted.

  The operation in this embodiment will be described.

  When the thickness of the sheet P input through the operation panel 48 or the like is less than the predetermined value T1, the distance between the rotation axes on the other axial end side of the intermediate transfer belt 14 and the transfer roller 34 is adjusted by adjusting the rotation phase of the motor 44. Is set to a predetermined value L1.

  When the thickness of the sheet P input from the operation panel 48 or the like is not less than the predetermined value T1 and less than the predetermined value T2, the other axial end of the intermediate transfer belt 14 and the transfer roller 34 is adjusted by adjusting the rotational phase of the motor 44. The distance between the rotation axes on the side is set to a predetermined value L2 that is wider than the case where the thickness of the paper P is less than the predetermined value T1.

  Further, when the thickness of the sheet P input through the operation panel 48 or the like is equal to or greater than the predetermined value T2, the rotation axis of the intermediate transfer belt 14 and the transfer roller 34 on the other axial end side is adjusted by adjusting the rotation phase of the motor 44. The distance is set to a predetermined value L3 that is wider than the case where the thickness of the paper P is equal to or greater than the predetermined value T1 and less than the predetermined value T2.

  Here, as the thickness (basis weight) of the sheet P increases, the contact position of the leading end of the sheet P with the driven roller 30 and the transfer roller 34 shifts greatly toward the upstream side in the transport direction. The contact angle and contact pressure between the driven roller 30 and the transfer roller 34 are increased, thereby increasing the load torque T (see FIG. 4).

  Therefore, in the present embodiment, as the thickness of the paper P increases, the difference between the rotation axis distance between the intermediate transfer belt 14 and the transfer roller 34 before the paper P is sandwiched between the one end side and the other end side in the axial direction. By increasing the amount, an increase in contact angle and contact pressure between the leading edge of the paper P and the driven roller 30 and the transfer roller 34 can be suppressed, and thus an increase in the load torque T (see FIG. 4) can be suppressed.

  Thus, for example, even when a thick sheet P such as a thick sheet is caused to enter between the intermediate transfer belt 14 and the transfer roller 34, the peripheral speed of the intermediate transfer belt 14 is converged to the set peripheral speed in a short time. Is possible.

  In the present embodiment, the conveyance speed of the paper P is variably controlled based on the thickness information of the paper P input by the user using the paper thickness input device such as the operation panel 48. For example, a displacement sensor, an ultrasonic sensor, or the like is used. Alternatively, the thickness of the paper P may be detected by the thickness sensor, and the rotational phase of the motor 44 may be adjusted based on the detection result.

  Next, a third embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the structure similar to 1st, 2nd embodiment, and description is abbreviate | omitted.

  As shown in FIG. 10, the inkjet recording apparatus 100 according to the present embodiment includes a conveyance belt 110 instead of the intermediate transfer belt 14 in the inkjet recording apparatuses 10 and 100 according to the first and second embodiments. In addition, a charging roller (pressing roller) 112 is pressed against the upper portion of the driving roller 22 via a conveying belt 110.

  The charging roller 112 is connected to a power source 113 and is driven while sandwiching the conveyance belt 110 and the paper P between the driving roller 22 and presses the paper P against the conveyance belt 110. At that time, since a predetermined potential difference is generated between the grounded driving roller 22 and the charging roller 112, the sheet P is charged and electrostatically adsorbed to the transport belt 110.

  Further, the conveyance roller pair 40 is disposed on the opposite side of the drive roller 22 and the charging roller 112 from the ink jet recording heads 12Y, 12M, 12C, and 12K, and the sheet P passes between the charging roller 112 and the conveyance belt 110. Transport.

  Here, as the support mechanism of the charging roller 112, the support mechanism of the transfer roller 34 in the first embodiment or the second embodiment is employed.

  Next, the operation in this embodiment will be described.

  The sheet P is plunged into the nip portion between the driving roller 22 and the charging roller 112 by the conveying roller pair 50. The sheet P is pressed against the conveyance belt 110 by the charging roller 112 and is electrostatically attracted to the conveyance belt 110 by being charged by the charging roller 112 and the driving roller 22.

  Then, the paper P is passed through the position facing the ink jet recording heads 12Y, 12M, 12C, and 12K by the transport belt 110 rotated by the driving roller 22, and at that time, the ink jet recording heads 12Y, 12M, 12C, and 12K are passed. Ink ejection is performed to form a full-color ink image on the paper P.

  The paper P on which the ink image is formed is peeled off from the transport belt 110 by a peeling member (not shown) on the driven roller 24, and then transported downstream by the transport roller (not shown), and finally the outside of the apparatus. Is discharged.

  Here, in this embodiment, the support mechanism for the transfer roller 34 in the first embodiment or the second embodiment is adopted as the support mechanism for the charging roller 112, so that the first embodiment or the second embodiment is different from the first embodiment. Similarly, it is possible to converge the speed fluctuation of the transport belt 110 when the paper P enters between the transport belt 110 and the charging roller 112 within an allowable time, and thus during ink image formation. Since the conveyance speed of the paper P can be stabilized, image quality deterioration such as color misregistration and color unevenness can be suppressed.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to the contractor. For example, in the present embodiment, the present invention has been described by taking an inkjet recording apparatus as an example, but the present invention can also be applied to a transfer roller pair, a fixing roller pair, and the like of an image forming apparatus using an electrophotographic system.

  In an ink jet recording type image forming apparatus that forms an image by ejecting ink to a recording medium on a rotating intermediate transfer belt or a rotating conveyance belt, a toner image is brought into contact with the intermediate transfer belt or the recording medium. As compared with the electrophotographic image forming apparatus to be transferred, the effect of applying the present invention is remarkable. Further, when a thick resin card such as a credit card is used as the recording medium, the effect of applying the present invention is remarkable.

  Next, a reference example will be described. In addition, the same code | symbol is attached | subjected to the structure similar to the above-mentioned 1st thru | or 3rd embodiment, and description is abbreviate | omitted.

  As shown in FIG. 11, an ink jet recording apparatus (image forming apparatus) 200 according to this reference example includes an intermediate transfer belt (rotating body) 14 on which an ink image (image) is formed on an outer peripheral surface (peripheral surface), And a transfer roller 34 that rotates with the intermediate transfer belt 14 sandwiching the paper P and transfers the ink image formed on the outer peripheral surface of the intermediate transfer belt 14 to the paper P. A sheet P having a tip shape with a width (in a direction perpendicular to the thickness direction) of the cross section viewed from the transport direction from the leading end side is narrowed between the intermediate transfer belt 14 and the transfer roller 34. It is characterized by being transported to.

  In addition, the inkjet recording apparatus 200 includes a paper cutter (first cutting unit) 202 that cuts the leading end of the paper P into a concavo-convex shape on the upstream side in the transport direction of the transfer roller 34.

  Further, the ink jet recording apparatus 200 has a paper cutter (second cutting means) 204 that cuts the leading edge of the paper P in a straight line on the downstream side in the transport direction of the transfer roller 34.

  As shown in FIG. 12, the paper cutter 202 includes a pair of rollers 206, and a cutting blade 208 having a zigzag-shaped blade portion formed on the peripheral surface of each roller 206 is disposed along the axial direction. It is installed. The pair of cutting blades 208 are disposed so as to overlap each other during one rotation of the pair of rollers 206, and the leading end portion of the paper P is set between the pair of rollers 206, and the pair of rollers 206 is arranged. By making one round, the leading edge of the paper P is cut into a zigzag shape.

  As shown in FIG. 13, by arranging the cutting blade 208 to be inclined with respect to the axial direction of the roller 206, it is possible to cut the paper P while it is being conveyed.

  Next, the operation of this reference example will be described.

  When the leading end of the paper P is transported to the pair of rollers 206, the transport of the paper P is stopped, and the paper cutter 202 (see FIG. 11) is operated, so that the leading edge of the paper P is cut into a zigzag shape. Is done. Then, as shown in FIG. 14, the conveyance of the paper P is resumed and conveyed between the intermediate transfer belt 14 and the transfer roller 34.

  At this time, the entry of the leading end of the sheet P between the intermediate transfer belt 14 and the transfer roller 34 starts from the top of the leading end (the pointed point toward the leading end) and is recessed toward the bottom (rear end). Ends with the root part).

  Accordingly, it is possible to obtain the same effect as the case where the paper P is skewed with respect to the traveling direction to enter between the intermediate transfer belt 14 and the transfer roller 34. As shown in the graph of FIG. The rise of the load torque T generated in the driven roller 30 and the transfer roller 34 at the time of rushing can be made gentle compared with the case where the leading end of the paper P is linear.

  Therefore, the amount of deceleration with respect to the target peripheral speed of the intermediate transfer belt 14 when the sheet P enters can be reduced as compared with the case where the leading end portion of the sheet P is linear, and therefore the sheet is compared with this case. The peripheral speed of the intermediate transfer belt 14 at the time of P entry can be converged to the target speed in a short time.

  The leading edge of the paper P that has passed between the intermediate transfer belt 14 and the transfer roller 34 is cut into a straight line by a paper cutter 204 (see FIG. 11). As a result, the leading edge of the paper P discharged out of the apparatus has a linear shape, so that the user does not feel uncomfortable.

  In addition to the zigzag shape shown in FIG. 15A, the leading end shape of the paper P includes a shape in which triangular convex portions are formed at predetermined intervals (see FIG. 15B), and a trapezoidal shape. A shape in which convex portions continue (see FIG. 15C), a shape in which semicircular convex portions continue (see FIG. 15D), a semicircular convex portion and a semicircular concave portion Other shapes such as alternately arranged shapes (see FIG. 15E) are also applicable.

1 is a side view showing an outline of an ink jet recording apparatus according to a first embodiment of the present invention. (A), (B) is a front view which shows the outline of the transfer part in the inkjet recording device shown in FIG. (A), (B) is a schematic front view which shows the state before and behind the paper rush of the transfer part shown in FIG. (A), (B) is a schematic side view which shows the state before and behind the paper rush of a transfer part. 3 is a graph showing a relationship between a load torque generated in an intermediate transfer belt when a sheet enters and a sheet moving distance in the transfer unit shown in FIG. (A) and (B) are side views showing an outline of a transfer portion in the ink jet recording apparatus according to the first embodiment of the present invention. 6 is a graph showing a relationship between a load torque generated in an intermediate transfer belt when a sheet enters and a sheet moving distance in an inkjet recording apparatus according to a comparative example. (A), (B) is a side view which shows the modification of the transfer part in the inkjet recording device which concerns on 1st Embodiment of this invention. (A), (B) is a front view which shows the outline of the transfer part in the inkjet recording device which concerns on 2nd Embodiment of this invention. It is a side view which shows the outline of the inkjet recording device which concerns on 3rd Embodiment of this invention. It is a side view which shows the outline of the inkjet recording device which concerns on a reference example. It is a perspective view which shows the transfer part in the inkjet recording device shown in FIG. It is a top view which shows the paper cutter with which the inkjet recording device shown in FIG. 12 is provided. It is a top view which shows the modification of the paper cutter shown in FIG. (A)-(E) are top views which show the front-end | tip shape of the paper conveyed in the inkjet recording device shown in FIG.

Explanation of symbols

10 Inkjet recording devices 12Y-K Inkjet recording head (image forming means)
14 Intermediate transfer belt (rotating body)
16 Bearing 28 Compression coil spring (biasing means)
30A Rotating shaft 32 Positioning member 34A Rotating shaft 34 Transfer roller 38 Rotating cam 44 Motor (driving means)
46 Control unit (control means)
100 Inkjet recording apparatus 110 Conveying belt (rotating body)
112 Charging roller (pressing roller)
P paper (recording medium)

Claims (8)

A rotating body on which an image is formed on the peripheral surface;
A transfer roller that rotates with the rotating body sandwiching a recording medium, and transfers an image formed on the peripheral surface of the rotating body to the recording medium;
A rotation axis distance regulating means for making the distance between the rotation axes of the rotating body and the transfer roller before sandwiching the recording medium different between one end side and the other end side in the axial direction;
An image forming apparatus comprising: It has a bearing that supports the transfer roller so as to be able to contact and separate from the rotating body,
The rotation axis distance regulating means is
Biasing means for biasing the transfer roller toward the rotating body;
The transfer roller is disposed on one or both ends in the axial direction and on the rotating body side of the rotating shaft of the transfer roller, the bearing is pressed by the urging means, and the rotating shaft of the transfer roller is connected to the rotating body of the rotating body. A positioning member that is inclined with respect to the rotation axis;
The image forming apparatus according to claim 1, further comprising: The rotation axis distance regulating means is configured to be able to adjust a difference amount between the rotation axis distance between the rotating body and the transfer roller before the recording medium is sandwiched between the one end side and the other end side in the axial direction. And
Driving means for causing the rotation axis distance regulating means to perform an adjustment operation;
Control means for controlling the drive means so that the difference amount increases as the thickness of the recording medium increases;
The image forming apparatus according to claim 1, further comprising: It has a bearing that supports the transfer roller so as to be able to contact and separate from the rotating body,
The rotation axis distance regulating means is
Biasing means for biasing the transfer roller toward the rotating body;
The transfer roller is disposed at one or both ends in the axial direction and on the rotating body side of the rotating shaft of the transfer roller, and the bearing is pressed by the urging means. A rotation cam that is inclined with respect to the rotation axis and is rotated by the driving means to change an inclination angle of the rotation axis of the transfer roller with respect to the rotation axis of the rotating body;
The image forming apparatus according to claim 3, further comprising: A rotating body that holds and conveys a recording medium on the peripheral surface;
Image forming means for forming an image on a recording medium conveyed by the rotating body;
A pressing roller that rotates in contact with the circumferential surface of the rotating body with the recording medium interposed therebetween, and presses the recording medium against the rotating body;
A rotation axis distance regulating means for making the distance between the rotation axes of the rotating body and the pressing roller before sandwiching the recording medium different between one end side and the other end side in the axial direction;
An image forming apparatus comprising: It has a bearing that supports the pressing roller so as to be able to contact and separate from the rotating body,
The rotation axis distance regulating means is
Urging means for urging the pressing roller toward the rotating body;
One end side or both end sides of the pressing roller in the axial direction and on the rotating body side of the rotating shaft of the pressing roller, the bearing is pressed by the biasing means, and the rotating shaft of the pressing roller is connected to the rotating body of the rotating body. A positioning member that is inclined with respect to the rotation axis;
The image forming apparatus according to claim 5, further comprising: The rotation axis distance regulating means is configured to be able to adjust a difference amount between the rotation axis distance between the rotating body and the pressing roller before the recording medium is sandwiched between the one end side and the other end side in the axial direction. And
Driving means for causing the rotation axis distance regulating means to perform an adjustment operation;
Control means for controlling the drive means so that the difference amount increases as the thickness of the recording medium increases;
The image forming apparatus according to claim 5, further comprising: It has a bearing that supports the pressing roller so as to be able to contact and separate from the rotating body,
The rotation axis distance regulating means is
Urging means for urging the pressing roller toward the rotating body;
The bearing is pressed by the urging means, arranged at one end side or both end sides in the axial direction of the pressing roller and on the rotating body side from the rotating shaft of the pressing roller, and the rotating shaft of the pressing roller is connected to the rotating body of the rotating body. A rotating cam that is inclined with respect to the rotating shaft and is rotated by the driving means to change an inclination angle of the rotating shaft of the pressing roller with respect to the rotating shaft of the rotating body;
The image forming apparatus according to claim 7, further comprising:

Images