JP2018153960A - Liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a skew while restraining an increase in carrying load and/or deterioration in the carrying accuracy.SOLUTION: A carrying part 20 includes upstream roller pairs 21 arranged upstream of a carrying passage relative to a discharge part 30 and downstream roller pairs 22 arranged downstream of the carrying passage relative to the discharge part 30. Carrying force of the upstream roller pairs 21 is larger than carrying force of the downstream roller pairs 22. A carrying speed of a sheet 100 by the upstream roller pairs 21 is lower than a carrying speed of the sheet 100 by the downstream roller pairs 22. A surface roller 21a of the upstream roller pairs 21 includes four upstream spur rollers 21a1. A surface roller 22a of the downstream roller pairs 22 includes four downstream spur rollers 22a1. A rocking range in a carrying surface (a surface parallel to the axial direction and the carrying direction of the roller) relative to a rotary shaft 22a1x of the respective downstream spur rollers 22a1 is larger than a rocking range in the carrying surface relative to the rotary shaft 21a1x of the respective upstream spur rollers 21a1.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a liquid ejection apparatus including a conveyance unit that conveys a recording medium and an ejection unit that has a plurality of ejection ports that eject liquid to the recording medium.

  In Patent Document 1 (FIG. 2), a conveyance roller pair (upstream roller pair) disposed upstream of the conveyance path with respect to the recording head (ejection unit), and a downstream of the conveyance path with respect to the recording head. An image recording apparatus including a conveying device including a pair of paper discharge rollers (a pair of downstream rollers) is disclosed. The surface roller of the upstream roller pair is a pinch roller having no protrusion on the outer peripheral surface, whereas the surface roller of the downstream roller pair is a spur roller having one or more protrusions formed on the outer peripheral surface. By adopting a spur roller as the surface roller of the downstream roller pair, it is possible to suppress the transfer of the liquid landed on the surface of the recording medium to the surface roller.

JP 2011-245835 A

  By the way, when the recording medium is transported between the upstream roller pair and the downstream roller pair, the recording medium can be skewed. In order to prevent skewing, the holding force of the upstream roller pair (the holding force of the recording medium by the front roller and the back roller) is increased, and the front roller of the upstream roller pair is made of a material having a high friction coefficient such as rubber. For this reason, it is conceivable to increase the regulation force in the conveyance direction of the recording medium by the upstream roller pair.

  However, when the clamping force of the upstream roller pair is increased, the conveyance load is increased. In addition, when the front roller of the upstream roller pair is made of rubber, the rubber has high elasticity, so the front roller does not rotate smoothly, and the conveyance accuracy may deteriorate.

  An object of the present invention is to provide a liquid ejection apparatus capable of preventing skewing while suppressing an increase in transport load and deterioration in transport accuracy.

  A liquid ejection apparatus according to the present invention includes: a conveyance unit that conveys a recording medium along a conveyance path; and an ejection unit that has a plurality of ejection ports that eject liquid onto the surface of the recording medium conveyed by the conveyance unit. The transport unit includes an upstream roller pair disposed upstream of the transport path with respect to the discharge unit, and a downstream roller pair disposed downstream of the transport path with respect to the discharge unit, Each of the upstream roller pair and the downstream roller pair includes a front roller that contacts the front surface of the recording medium, and a back roller that contacts a back surface opposite to the front surface of the recording medium. The upstream roller is configured to convey the recording medium by applying a conveying force to the recording medium by rotating in opposite directions around the respective rotation axes while sandwiching the recording medium, and the upstream roller versus The conveyance force is larger than the conveyance force of the downstream roller pair, and the conveyance speed of the recording medium by the upstream roller pair is smaller than the conveyance speed of the recording medium by the downstream roller pair, and the surface of the upstream roller pair The roller includes a plurality of upstream spur rollers that are spur rollers having one or more protrusions formed on an outer peripheral surface, and the front roller of the downstream roller pair includes at least one downstream spur roller that is the spur roller, The swing range of the downstream spur roller in the transport plane parallel to the axial direction of the roller and the direction along the transport path with respect to the rotation shaft of the roller is the roller of each of the plurality of upstream spur rollers. Is larger than a swinging range in the transport plane with respect to the rotation shaft.

  According to the present invention, a plurality of upstream spur rollers are employed as the surface rollers of the upstream roller pair, and the swing range of the downstream spur roller that is the surface roller of the downstream roller pair is larger than the swing range of each upstream spur roller. To do. As a result, the protrusion of the upstream spur roller bites into the recording medium without increasing the clamping force of the upstream roller pair or the surface roller of the upstream roller pair is made of rubber, and the upstream roller pair conveys the recording medium. The direction is regulated (the downstream roller pair slips with respect to the recording medium), and skewing can be prevented. Therefore, since it is not necessary to increase the clamping force of the upstream roller pair, it is possible to suppress an increase in the conveyance load, and it is not necessary to configure the surface roller of the upstream roller pair with rubber, so that the conveyance accuracy is deteriorated. Can be suppressed. That is, skew can be prevented while suppressing an increase in transport load and deterioration in transport accuracy.

  Each of the plurality of upstream spur rollers may be supported by the rotation shaft of the roller such that a swing range in the transport surface with respect to the rotation shaft of the roller becomes zero. In this case, the swing range can be reduced with a relatively simple configuration.

  The liquid ejection apparatus according to the present invention may be configured such that each of the plurality of upstream spur rollers is opposed to the axial direction of the roller and is opposed to the axial direction, and each of the plurality of upstream spur rollers is disposed on the opposed wall. And a plurality of urging members that are urged toward the surface to come into contact with the opposing wall. If the upstream spur roller moves in the axial direction of the recording medium during conveyance, skewing may occur. On the other hand, according to the above configuration, the upstream spur roller is prevented from moving in the axial direction of the roller by biasing the upstream spur roller against the opposing wall by the biasing member and contacting the opposing wall. The problem of skewing can be suppressed.

  The conveying unit conveys the recording medium by aligning the axial center of the recording medium with the axial center of each of the upstream roller pair and the downstream roller pair, and the plurality of biasing members include Each of the plurality of upstream spur rollers may be biased in a direction away from the axial center. In this case, it is easy to maintain the flatness of the recording medium.

  The urging forces of the plurality of urging members may be the same. When the urging forces of the plurality of urging members are different from each other and it is necessary to attach the urging member having a predetermined urging force to a predetermined position, the mounting defect (attach each urging member to a position different from the predetermined position) May occur). On the other hand, according to the said structure, since the urging | biasing force of several urging | biasing members is mutually the same, the problem of attachment defect can be suppressed.

  In the plurality of urging members, the urging member disposed away from the center in the axial direction may have a larger urging force. In this case, wrinkles in the axial direction of the recording medium can be corrected.

  The plurality of biasing members may bias the plurality of upstream spur rollers in alternating directions along the axial direction of the plurality of upstream spur rollers. In this case, it is possible to cope with a conveyance form other than the center alignment.

  A groove is provided on the outer peripheral surface of the back roller of the upstream roller pair, and each of the plurality of upstream spur rollers has the protrusion facing the groove, and the protrusion is the back roller of the upstream roller pair. May be separated from the outer peripheral surface. When the protrusion of the upstream spur roller contacts the outer peripheral surface of the back roller of the upstream roller pair, the protrusion can be worn. On the other hand, according to the said structure, since the protrusion of an upstream spur roller is spaced apart from the outer peripheral surface of the back roller of an upstream roller pair, abrasion of a protrusion can be prevented. In addition, when the protrusion of the upstream spur roller contacts the outer peripheral surface of the back roller of the upstream roller pair, the recording medium is clamped at one point of contact between the protrusion and the outer peripheral surface of the back roller of the upstream roller pair for each upstream spur roller. Is done. On the other hand, according to the above configuration, for each upstream spur roller, the recording medium is sandwiched at three points: a protrusion and two edges that define grooves on the outer peripheral surface of the back roller of the upstream roller pair. The holding power of the recording medium is improved.

  The front roller of the upstream roller pair may further include a pinch roller having no protrusion formed on the outer peripheral surface. In this case, the conveying force of the upstream roller pair can be increased without increasing the number of upstream spur rollers, and the conveying accuracy can be improved.

  An outer diameter of the pinch roller may be larger than an outer diameter of each of the plurality of upstream spur rollers. When skew correction is performed in the upstream roller pair, if the leading edge of the recording medium comes into contact with the protrusion of the upstream spur roller, the protrusion may be damaged. On the other hand, according to the above configuration, when skew correction is performed in the upstream roller pair, the front end of the recording medium is suppressed from coming into contact with the protrusion of the upstream spur roller, and the protrusion can be prevented from being damaged.

  The pinch roller may be disposed upstream of the transport path with respect to the plurality of upstream spur rollers. According to the above configuration, when skew correction is performed in the upstream roller pair, the front end of the recording medium is suppressed from coming into contact with the protrusion of the upstream spur roller, and damage to the protrusion can be prevented.

  A plurality of the pinch rollers and the plurality of upstream spur rollers are alternately arranged along the axial direction of the upstream roller pair, and a recording medium formed by the back roller of the upstream roller pair of each of the plurality of pinch rollers The pinching force is larger than the pinching force of the recording medium by the back roller of the upstream roller pair of each of the plurality of upstream spur rollers, and the pinch rollers arranged near the center in the axial direction are arranged in the plurality of pinch rollers. The holding force of the plurality of upstream spur rollers may be smaller as the roller is larger, and the fluctuation range of the clamping force of the plurality of upstream spur rollers may be smaller than the fluctuation range of the clamping force of the plurality of pinch rollers. In this case, skew can be prevented more reliably.

  According to the present invention, it is possible to prevent skewing while suppressing an increase in conveyance load and deterioration in conveyance accuracy.

FIG. 2 is a cross-sectional view along the vertical direction showing the inside of the printer according to the first embodiment of the present invention. It is a fragmentary sectional view of the discharge part in the printer concerning a 1st embodiment of the present invention. FIG. 2 is a plan view illustrating a roller pair and a discharge unit of a conveyance unit in the printer according to the first embodiment of the present invention. FIG. 4 is a diagram of an upstream roller pair as seen from the direction of arrow IV in FIG. 3 in the printer according to the first embodiment of the present invention. It is a figure which shows the clamping force of the upstream spur roller and pinch roller which comprise the surface roller of an upstream roller pair. It is a figure corresponding to FIG. 4 of the upstream roller pair in the printer which concerns on 2nd Embodiment of this invention. It is a figure corresponding to FIG. 4 of the upstream roller pair in the printer which concerns on 3rd Embodiment of this invention. It is a figure corresponding to FIG. 4 of the upstream roller pair in the printer which concerns on 4th Embodiment of this invention.

<First Embodiment>
As shown in FIG. 1, the printer 1 according to the first embodiment of the present invention includes a paper feed tray 10 that can store and accommodate a plurality of sheets 100, and a plurality of sheets 100 that are accommodated in the sheet feed tray 10. Among them, a transport unit 20 that transports the uppermost sheet 100 along the transport path R, and a discharge unit that has a plurality of discharge ports 30x (see FIG. 2) that discharge ink onto the surface of the sheet 100 transported by the transport unit 20. 30, a platen 40 facing the ejection surface 30 a in which a plurality of ejection ports 30 x in the ejection unit 30 are opened, and a paper discharge tray 50 that receives the paper 100 conveyed by the conveyance unit 20. The paper 100 is transported from the paper feed tray 10 along the transport path R, and after ink is discharged onto the surface and recording is performed, the paper 100 is received by the paper discharge tray 50.

  As shown in FIG. 2, the discharge unit 30 includes a flow path unit 30m and an actuator unit 30n.

  The lower surface of the flow path unit 30m corresponds to the discharge surface 30a. Inside the flow path unit 30m, a common flow path 30y communicating with an ink tank (not shown) and an individual flow path 30z for each discharge port 30x are formed. The individual flow path 30z is a flow path from the outlet of the common flow path 30y to the discharge port 30x through the pressure chamber 30z1. A plurality of pressure chambers 30z1 are opened on the upper surface of the flow path unit 30m.

  The actuator unit 30n includes a diaphragm 30n1 disposed on the top surface of the flow path unit 30m so as to cover the plurality of pressure chambers 30z1, a piezoelectric layer 30n2 disposed on the top surface of the diaphragm 30n1, and a plurality of actuator units 30n2 on the top surface of the piezoelectric layer 30n2. And a plurality of individual electrodes 30n3 arranged to face each of the pressure chambers 30z1. A portion sandwiched between each individual electrode 30n3 and each pressure chamber 30z1 in the vibration plate 30n1 and the piezoelectric layer 30n2 functions as an individual unimorph actuator for each pressure chamber 30z1, and the voltage applied to each individual electrode 30n3 by the head driver 30d. It can be deformed independently according to the application of. By deforming the actuator so as to be convex toward the pressure chamber 30z1, the volume of the pressure chamber 30z1 is reduced, pressure is applied to the ink in the pressure chamber 30z1, and ink is ejected from the ejection port 30x.

  The ejection unit 30 is a line type, and ejects ink from each ejection port 30x while being fixed at a fixed position above the platen 40.

  The transport unit 20 is upstream of the transport path R with respect to the paper feed roller 11 disposed so as to be in contact with the uppermost paper 100 among the plurality of papers 100 accommodated in the paper feed tray 10 and the discharge unit 30. It includes an upstream roller pair 21 disposed, a downstream roller pair 22 disposed downstream of the transport path R with respect to the discharge unit 30, and a guide plate 20g that defines the transport path R.

  As shown in FIG. 3, the transport unit 20 is configured to transport the paper 100 with the axial center of the paper 100 aligned with the axial center O of each of the upstream roller pair 21 and the downstream roller pair 22. ing.

  The upstream roller pair 21 and the downstream roller pair 22 have front rollers 21 a and 22 a that contact the surface of the paper 100, and back rollers 21 b and 22 b that contact the back surface opposite to the front surface of the paper 100, respectively. The front rollers 21 a and 22 a and the back rollers 21 b and 22 b rotate in opposite directions around the respective rotation axes while sandwiching the paper 100, so that a transport force is applied to the paper 100 and the paper 100 is transported. It is configured.

  The conveying force of the upstream roller pair 21 is larger than the conveying force of the downstream roller pair 22. The conveying force is represented by the product of the friction coefficient of the outer peripheral surfaces of the front rollers 21a and 22a and the rear rollers 21b and 22b and the clamping force of the paper 100 by the front rollers 21a and 22a and the rear rollers 21b and 22b. Can do.

  The rotational speed of the upstream roller pair 21 is smaller than the rotational speed of the downstream roller pair 22. That is, the conveyance speed of the paper 100 by the upstream roller pair 21 is smaller than the conveyance speed of the paper 100 by the downstream roller pair 22.

  Both the back roller 21b of the upstream roller pair 21 and the back roller 22b of the downstream roller pair 22 are constituted by one roller that is long in the axial direction. The back rollers 21b and 22b can rotate around the rotation shafts 21bx and 22bx, respectively.

  The front roller 21a of the upstream roller pair 21 includes four upstream spur rollers 21a1 and five pinch rollers 21a2. The upstream spur roller 21 a 1 and the pinch roller 21 a 2 are alternately arranged at equal intervals along the axial direction of the upstream roller pair 21.

  The surface roller 22a of the downstream roller pair 22 includes four downstream spur rollers 22a1. The downstream spur rollers 22 a 1 are arranged at equal intervals along the axial direction of the downstream roller pair 22.

  The four upstream spur rollers 21a1 and the four downstream spur rollers 22a1 are spur rollers in which a large number of protrusions 21ap and 22ap are formed on the outer peripheral surface, respectively (see FIG. 1). Each of the five pinch rollers 21a2 is made of a high-hardness material (resin, metal, etc.) and has a circular cross section (no protrusions are formed on the outer peripheral surface).

  The four upstream spur rollers 21a1, the five pinch rollers 21a2, and the four downstream spur rollers 22a1 are supported by independent rotary shafts 21a1x, 21a2x, and 22a1x, respectively, and can rotate around the rotary shafts. The rotation shafts 21a1x, 21a2x, 22a1x are supported by the casing 1x of the printer 1 via springs (springs 21a1s, 21a2s, etc. in FIG. 4). The rotation shafts 21a1x, 21a2x, and 22a1x are inserted through the rollers 21a1, 21a2, and 22a1, respectively. The rollers 21a1, 21a2, and 22a1 are rotatable with respect to the rotation shafts 21a1x, 21a2x, and 22a1x.

  The upstream spur roller 21a1 is press-fitted into each rotating shaft 21a1x. That is, only a slight gap (that is, rotatable with respect to the rotating shaft 21a1x) is formed between the outer peripheral surface of the rotating shaft 21a1x and the inner peripheral surface of the upstream spur roller 21a1. Thereby, in the conveyance surface (surface parallel to the axial direction of the said roller and the direction along the conveyance path | route R (conveyance direction) with respect to the rotating shaft 21a1x of each upstream spur roller 21a1: The surface along the paper surface of FIG. The swing range is zero.

  The downstream spur roller 22a1 is swingably supported on each rotating shaft 22a1x. That is, a relatively large gap is formed between the outer peripheral surface of the rotating shaft 22a1x and the inner peripheral surface of the downstream spur roller 22a1 (see FIG. 3). Therefore, the swing range in the transport surface of each downstream spur roller 22a1 with respect to the rotation shaft 22a1x is larger than the swing range in the transport surface of each upstream spur roller 21a1 with respect to the rotation shaft 21a1x.

  The four upstream spur rollers 21a1 are disposed on the same axis. The five pinch rollers 21a2 are arranged on the same axis. The four downstream spur rollers 22a1 are disposed on the same axis. Each pinch roller 21a2 is disposed upstream of the transport path R with respect to each upstream spur roller 21a1 (see FIGS. 1 and 3).

  The four upstream spur rollers 21a1 have the same size and shape. The five pinch rollers 21a2 have the same size and shape. The four downstream spur rollers 22a1 have the same size and shape. The outer diameter of each pinch roller 21a2 is larger than the outer diameter of each upstream spur roller 21a1 (see FIGS. 1, 3, and 4).

  The back roller 21b is made of metal, and the outer peripheral surface is coated with a material having a high friction coefficient. On the outer peripheral surface of the back roller 21b, as shown in FIG. 4, grooves 21by are provided in portions facing the four upstream spur rollers 21a1, respectively. In each upstream spur roller 21a1, the protrusion 21ap faces the groove 21by, and the protrusion 21ap is separated from the outer peripheral surface of the back roller 21b.

  The four upstream spur rollers 21a1 and the five pinch rollers 21a2 are urged toward the back roller 21b by a pair of springs 21a1s and 21a2s, respectively. Each spring 21a1s, 21a2s has one end fixed to the housing 1x and the other end fixed to the rotation shafts 21a1x, 21a2x. The urging force of the springs 21a1s and 21a2s defines the holding force of the paper 100 by the rollers 21a1 and 21a2 and the back roller 21b. The pinching force of each pinch roller 21a2 is greater than the pinching force of each upstream spur roller 21a1.

  Of the five pinch rollers 21a2, the pinching rollers disposed closer to the axial center O have a larger clamping force. That is, the urging force of the spring 21a2s provided for the pinch roller 21a2 located at the center O in the axial direction is the largest, and is provided for the two pinch rollers 21a2 adjacent to both sides in the axial direction of the pinch roller 21a2. The urging force of the spring 21a2s is the second largest, and the urging force of the springs 21a2s provided to the two pinch rollers 21a2 located on both outer sides in the axial direction is the smallest.

  In the four upstream spur rollers 21a1, the gripping force is smaller as the upstream spur roller disposed near the center O in the axial direction. That is, the urging force of the spring 21a1s provided to the two upstream spur rollers 21a1 located closest to the axial center O is provided to the two upstream spur rollers 21a1 located on both outer sides in the axial direction. Smaller than the biasing force of the spring 21a1s.

  As shown in FIG. 5, the fluctuation range of the clamping force in the four upstream spur rollers 21a1 is smaller than the fluctuation range of the clamping force in the five pinch rollers 21a2.

  As described above, according to the present embodiment, a plurality of upstream spur rollers 21a1 are adopted as the front roller 21a of the upstream roller pair 21, and the downstream spur roller 22a1 that is the front roller 22a of the downstream roller pair 22 is swung. The moving range is made larger than the swinging range of each upstream spur roller 21a1 (see FIG. 3). As a result, the protrusion 21ap of the upstream spur roller 21a1 bites into the sheet 100 without increasing the clamping force of the upstream roller pair 21 or the surface roller 21a of the upstream roller pair 21 is made of rubber, and the upstream roller pair 21 21 regulates the conveyance direction of the paper 100 (the downstream roller pair 22 slips with respect to the paper 100), and skewing can be prevented. Therefore, since it is not necessary to increase the clamping force of the upstream roller pair 21, it is possible to suppress an increase in the conveyance load, and it is not necessary to configure the front roller 21a of the upstream roller pair 21 with rubber, so that the conveyance accuracy is high. Can be prevented. That is, skew can be prevented while suppressing an increase in transport load and deterioration in transport accuracy.

  Each of the plurality of upstream spur rollers 21a1 is supported by the rotation shaft 21a1x so that the swing range in the transport surface with respect to the rotation shaft 21a1x is zero (see FIG. 3). In this case, the swing range can be reduced with a relatively simple configuration.

  A groove 21by is provided on the outer peripheral surface of the back roller 21b (see FIG. 4). In each upstream spur roller 21a1, the protrusion 21ap faces the groove 21by, and the protrusion 21ap is separated from the outer peripheral surface of the back roller 21b. When the protrusion 21ap of the upstream spur roller 21a1 contacts the outer peripheral surface of the back roller 21b, the protrusion 21ap can be worn. On the other hand, according to the said structure, since protrusion 21ap of the upstream spur roller 21a1 is spaced apart from the outer peripheral surface of the back surface roller 21b, abrasion of protrusion 21ap can be prevented. Further, when the protrusion 21ap of the upstream spur roller 21a1 contacts the outer peripheral surface of the back roller 21b, the sheet 100 is held at one point of contact between the protrusion 21ap and the outer peripheral surface of the back roller 21b for each upstream spur roller 21a1. . On the other hand, according to the above configuration, the sheet 100 is clamped at three points of the protrusion 21ap and the two edges 21be that define the groove 21by on the outer peripheral surface of the back roller 21b for each upstream spur roller 21a1. In addition, the clamping force of the paper 100 is improved.

  The front roller 21a of the upstream roller pair 21 further includes a pinch roller 21a2 in which no protrusion is formed on the outer peripheral surface (see FIG. 3). In this case, the conveyance force of the upstream roller pair 21 can be increased without increasing the number of the upstream spur rollers 21a1, and the conveyance accuracy can be improved. The pinch roller 21a2 has a small regulation force in the conveyance direction, and the conveyance direction is regulated by the upstream spur roller 21a1. Therefore, the pinch roller 21a2 does not adversely affect the skew.

  The outer diameter of the pinch roller 21a2 is larger than the outer diameter of each upstream spur roller 21a1 (see FIG. 1). When skew correction is performed in the upstream roller pair 21, if the leading edge of the paper 100 abuts on the protrusion 21ap of the upstream spur roller 21a1, the protrusion 21ap may be damaged. On the other hand, according to the above configuration, when skew correction is performed in the upstream roller pair 21, the leading edge of the paper 100 is suppressed from coming into contact with the protrusion 21ap of the upstream spur roller 21a1, thereby preventing the protrusion 21ap from being damaged. be able to.

  The pinch roller 21a2 is disposed upstream of the transport path R with respect to each upstream spur roller 21a1 (see FIG. 1). According to the above configuration, when skew correction is performed in the upstream roller pair 21, it is possible to prevent the leading edge of the paper 100 from coming into contact with the protrusion 21ap of the upstream spur roller 21a1, and to prevent the protrusion 21ap from being damaged.

  Pinch rollers 21a2 and upstream spur rollers 21a1 are alternately arranged along the axial direction of the upstream roller pair 21 (see FIG. 4). The pinching force of each pinch roller 21a2 is greater than the pinching force of each upstream spur roller 21a1. Of the five pinch rollers, the pinching roller disposed closer to the axial center O has a larger clamping force. The fluctuation range of the clamping force in the four upstream spur rollers 21a1 is smaller than the fluctuation width of the clamping force in the five pinch rollers 21a2 (see FIG. 5). In this case, skew can be prevented more reliably.

Second Embodiment
The printer according to the second embodiment of the present invention is the same as the printer 1 according to the first embodiment except that the configuration of the upstream roller pair is different from that of the printer 1 according to the first embodiment.

  As shown in FIG. 6, in the upstream roller pair 221 of the second embodiment, the rotation shafts 21a1x of the four upstream spur rollers 21a1 and the rotation shafts 21a2x of the five pinch rollers 21a2 are supported by the support member 221x. The support member 221x is supported by the housing 1x, is movable in the vertical direction with respect to the housing 1x in accordance with the biasing force of the springs 21a1s and 21a2s, and the upstream roller pair 221 with respect to the housing 1x. It is impossible to move in the axial direction.

  The upstream spur roller 21a1 is not press-fitted into each rotating shaft 21a1x. That is, a relatively large gap is formed between the outer peripheral surface of the rotating shaft 21a1x and the inner peripheral surface of the upstream spur roller 21a1. The upstream spur roller 21a1 is urged toward the opposing wall 221xw of the support member 221x by the spring 221s wound around each rotating shaft 21a1x, and is in contact with the opposing wall 221xw. The opposing wall 221xw is a wall that faces each upstream spur roller 21a1 in the support member 221x in the axial direction of the roller, and is fixed in the axial direction of the roller.

  The four springs 221s urge each upstream spur roller 21a1 in a direction away from the center O in the axial direction. The urging forces of the four springs 221s are the same as each other.

  As described above, the printer according to the present embodiment is configured so that each of the four upstream spur rollers 21a1 faces the axial direction of the rollers, the opposing wall 221xw fixed in the axial direction, and the four upstream spur rollers 21a1. And four springs 221s that urge each of them toward the opposing wall 221xw to contact the opposing wall 221xw. If the upstream spur roller 21a1 moves in the axial direction of the roller during conveyance of the paper 100, skew may occur. On the other hand, according to the present embodiment, each upstream spur roller 21a1 is urged against the opposing wall 221xw by the spring 221s and brought into contact with the opposing wall 221xw, whereby the upstream spur roller 21a1 moves in the axial direction of the roller. This can prevent the problem of skew.

  The transport unit 20 transports the paper 100 with the axial center of the paper 100 aligned with the axial center O of each of the upstream roller pair 21 and the downstream roller pair 22, and the four springs 221s The upstream spur roller 21a1 is urged away from the axial center O. In this case, it is easy to maintain the flatness of the paper 100.

  The urging forces of the four springs 221s are the same as each other. When the urging forces of the four springs 221s are different from each other and it is necessary to attach the spring 221s having a predetermined urging force to a predetermined position, the mounting is insufficient (the springs 221s are attached to a position different from the predetermined position). Can occur. On the other hand, according to the said structure, since the urging | biasing force of the four springs 221s is mutually the same, the problem of attachment defect can be suppressed.

<Third Embodiment>
The printer according to the third embodiment of the present invention is the same as the printer according to the second embodiment except that the configuration of the upstream roller pair is different from the printer according to the second embodiment.

  As shown in FIG. 7, in the upstream roller pair 321 of the third embodiment, the two springs 321s located closest to the axial center O are more than the two springs 321s located on both outer sides in the axial direction. The biasing force is small. That is, in the four springs 321 s, the springs arranged away from the axial center O have a larger urging force.

  The urging forces of the two springs 321s located closest to the axial center O are the same, and the urging forces of the two springs 321s located on both outer sides in the axial direction are the same.

  As described above, according to the present embodiment, in the four springs 321 s, the springs arranged away from the axial center O have a larger urging force. In this case, wrinkles in the axial direction of the paper 100 can be corrected.

<Fourth embodiment>
The printer according to the fourth embodiment of the present invention is the same as the printer according to the second embodiment except that the configuration of the upstream roller pair is different from the printer according to the second embodiment.

  As shown in FIG. 8, in the upstream roller pair 421 of the fourth embodiment, of the four springs 421s, the two springs 421s positioned on both outer sides in the axial direction are not on the outer side in the axial direction but on the center in the axial direction. The upstream spur roller 21a1 is urged toward O. That is, the four springs 421s urge each upstream spur roller 21a1 in an alternating direction along the axial direction of the upstream spur roller 21a1. The urging forces of the four springs 421s are the same as each other.

  As described above, according to the present embodiment, the four springs 421s urge the upstream spur rollers 21a1 in alternating directions along the axial direction of the upstream spur roller 21a1. In this case, it is possible to cope with a conveyance form other than the center alignment.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and various design changes can be made as long as they are described in the claims.

<Modification>
-The number of upstream spur rollers should just be plural, and is not limited to four.
-The number of downstream spur rollers should just be one or more, and is not limited to four.
-The number of pinch rollers is not limited to five. The pinch roller may be omitted.
The pinch roller and the upstream spur roller may not be alternately arranged along the axial direction of the upstream roller pair.
-The outer diameter of a pinch roller may be the same as the outer diameter of an upstream spur roller, and may be smaller than the outer diameter of an upstream spur roller.
The pinch roller may be disposed at the same position in the transport direction as the upstream spur roller, or may be disposed downstream of the transport path with respect to the upstream spur roller.
-A pinch roller and an upstream spur roller may be arrange | positioned on the same axis line.
-A pinch roller and an upstream spur roller may be supported by one rotating shaft. Further, a plurality of pinch rollers may be supported on one rotating shaft. A plurality of upstream spur rollers may be supported on one rotating shaft. In these cases, a pair of springs for urging each roller toward the back roller may be provided at both ends of the one rotating shaft.
-A discharge part is not limited to a line type, A serial type may be sufficient.
The liquid ejected by the ejection unit is not limited to ink, and may be any liquid (for example, a treatment liquid that aggregates or deposits components in the ink).
The recording medium is not limited to paper, and may be any recordable medium (for example, cloth).
The present invention is not limited to a printer, but can be applied to a facsimile machine, a copier, a multifunction machine, and the like.

1 Printer (Liquid ejection device)
20 conveying section 21; 221; 321; 421 upstream roller pair 21a surface roller 21a1 upstream spur roller 21a1x rotating shaft 21ap protrusion 21a2 pinch roller 21a2x rotating shaft 21b back roller 21bx rotating shaft 21by groove 22 downstream roller pair 22a downstream roller wheel 22a surface roller wheel 22a 22a1x Rotating shaft 22ap Protrusion 22b Back roller 22bx Rotating shaft 30 Discharge unit 30x Discharge port 100 Paper (recording medium)
221x support member 221xw opposing wall 221s; 321s; 421s Spring (biasing member)
R Transport route

Claims (12)

A transport unit for transporting the recording medium along the transport path;
An ejection unit having a plurality of ejection ports for ejecting liquid onto the surface of the recording medium conveyed by the conveyance unit;
The transport unit includes an upstream roller pair disposed upstream of the transport path with respect to the discharge unit, and a downstream roller pair disposed downstream of the transport path with respect to the discharge unit,
Each of the upstream roller pair and the downstream roller pair includes a front roller that contacts the front surface of the recording medium, and a back roller that contacts a rear surface opposite to the front surface of the recording medium, The back roller and the back roller are configured to convey the recording medium by applying a conveying force to the recording medium by rotating in opposite directions around the respective rotation axes while sandwiching the recording medium.
The conveyance force of the upstream roller pair is greater than the conveyance force of the downstream roller pair, and the conveyance speed of the recording medium by the upstream roller pair is smaller than the conveyance speed of the recording medium by the downstream roller pair,
The front roller of the upstream roller pair includes a plurality of upstream spur rollers that are spur rollers having one or more protrusions formed on an outer peripheral surface, and the front roller of the downstream roller pair is a downstream spur roller that is the spur roller. Including at least one
The swing range of the downstream spur roller in the transport plane parallel to the axial direction of the roller and the direction along the transport path with respect to the rotation shaft of the roller is the speed of each of the plurality of upstream spur rollers. A liquid ejecting apparatus, wherein the roller is larger than a swinging range in the transport surface with respect to the rotation shaft.   The plurality of upstream spur rollers are each supported by the rotation shaft of the roller so that a swing range in the transport surface with respect to the rotation shaft of the roller becomes zero. The liquid discharge apparatus according to 1. Each of the plurality of upstream spur rollers facing the axial direction of the roller, and an opposing wall fixed in the axial direction;
The liquid ejecting apparatus according to claim 1, further comprising: a plurality of urging members that urge each of the plurality of upstream spur rollers toward the opposing wall to contact the opposing wall. . The conveying unit conveys the recording medium by aligning the axial center of the recording medium with the axial center of each of the upstream roller pair and the downstream roller pair,
The liquid ejecting apparatus according to claim 3, wherein each of the plurality of urging members urges the plurality of upstream spur rollers in a direction away from the axial center.   The liquid ejecting apparatus according to claim 4, wherein the urging forces of the plurality of urging members are the same.   5. The liquid ejecting apparatus according to claim 4, wherein in the plurality of urging members, the urging member disposed farther from the axial center has a larger urging force.   The liquid ejecting apparatus according to claim 3, wherein the plurality of urging members urge the plurality of upstream spur rollers in alternate directions along an axial direction of the plurality of upstream spur rollers. A groove is provided on the outer peripheral surface of the back roller of the upstream roller pair,
The plurality of upstream spur rollers each have the protrusion facing the groove, and the protrusion is separated from the outer peripheral surface of the back roller of the upstream roller pair. The liquid discharge apparatus according to any one of the above.   The liquid ejecting apparatus according to claim 1, wherein the front roller of the pair of upstream rollers further includes a pinch roller having no protrusion formed on an outer peripheral surface.   The liquid ejecting apparatus according to claim 9, wherein an outer diameter of the pinch roller is larger than an outer diameter of each of the plurality of upstream spur rollers.   The liquid ejecting apparatus according to claim 9, wherein the pinch roller is disposed upstream of the transport path with respect to the plurality of upstream spur rollers. A plurality of the pinch rollers and the plurality of upstream spur rollers are alternately arranged along the axial direction of the upstream roller pair,
The holding force of the recording medium by the back roller of the upstream roller pair of each of the plurality of pinch rollers is larger than the holding force of the recording medium by the back roller of the upstream roller pair of each of the plurality of upstream spur rollers. ,
In the plurality of pinch rollers, the pinching roller disposed closer to the center in the axial direction has a larger clamping force.
12. The liquid ejection according to claim 9, wherein a fluctuation range of the clamping force in the plurality of upstream spur rollers is smaller than a fluctuation range of the clamping force in the plurality of pinch rollers. apparatus.

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