JP2018177393A - Conveyance device and inkjet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conveyance device capable of more precisely detecting floating of a sheet member, and to provide an inkjet recording device thereof.SOLUTION: The conveyance device comprises a drive part for peripherally moving a belt-like member of which a sheet member is placed on an outer periphery surface through a predetermined circulating path; a light emission part; a light reception part for detecting emission light traveling in an optical path extending in a direction crossing a moving direction along a plane through which a surface of the sheet member placed on the belt-like member passes, across both ends of the belt-like member in a width direction, out of light emitted from the light emission part; detection means for detecting floating from the outer periphery surface o the sheet member via change in an incidence state to the light reception part of the emission light; and an energizing part for energizing the belt-like member in a direction of suppressing warpage onto an outer peripheral surface side at a predetermined position in a circulating path in such a manner that the warpage in the belt-like member of which the warpage is generated on the outer peripheral surface side is suppressed within a range of not interrupting the optical path of the emission light.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a transport apparatus and an inkjet recording apparatus.

  Conventionally, ink is ejected from a nozzle provided on the ink ejection surface of an ink ejection unit to a sheet member such as paper or resin conveyed by a conveyance device, and the ink is landed in a desired pattern. There is an inkjet recording device that records an image. As a conveyance device in the inkjet recording apparatus, a belt-like member such as a conveyance belt on which a sheet member is placed on the outer peripheral surface is bridged by a plurality of conveyance rollers, and the belt rotates around the belt-like member by a predetermined circulation path A device for transporting a sheet member by moving is widely used.

  In such a conveying device, the contact range of the strip-shaped member with respect to the transport roller may be shifted in the axial direction of the transport roller, and the belt-shaped member may be unevenly distributed in the width direction. On the other hand, it is known that the uneven distribution of the belt-like member is corrected by applying tension to the belt-like member so as to make different tensions at both ends in the width direction of the belt-like member by inclining any of the transport rollers. It is done.

  In an inkjet recording apparatus using the above-described transport apparatus having a strip-shaped member, when the sheet member being transported is lifted from the outer peripheral surface of the strip-shaped member, various operations performed on the sheet member on the outer peripheral surface are properly performed. It will not be possible. For example, when the ink is discharged from the ink discharge unit to the sheet member which has risen, an error occurs in the landing position of the ink on the sheet member. In addition, when the sheet member lifted up from the outer peripheral surface and the ink discharge surface of the ink discharge portion come in contact with each other, the ink discharge surface may be contaminated and the normal ink discharge can not be performed.

  On the other hand, in the transport device, the surface of the sheet member placed on the belt-like member extends between the light-emitting part that emits light and the light emitted from the light-emitting part across the widthwise end of the belt-like member. There is a technique of detecting the floating of the sheet member by changing the incident state of the outgoing light to the light receiving part, which detects the outgoing light traveling along the light path extending along the passing surface, and detecting the change of the incident state of the outgoing light to the light receiving part. 1).

JP, 2016-190700, A

  However, in the above-described transport apparatus, the strip-shaped member may warp to the outer peripheral surface side due to the application of tension for correcting the uneven distribution of the strip-shaped member. When floating is detected on the recording medium placed on the belt-like member in the warped state as described above, if the warpage becomes larger than the detection range of the emitted light, the emitted light from the light emitting unit There is a problem that the light path is blocked by the belt-like member, and the floating of the sheet member can not be accurately detected.

  An object of the present invention is to provide a transport apparatus and an inkjet recording apparatus capable of detecting the floating of a sheet member more accurately.

In order to achieve the above object, the invention of a transport apparatus according to claim 1 is:
A conveying device for conveying a sheet member, wherein
A belt-like member on which the sheet member is placed on the outer peripheral surface;
A drive unit for moving the belt-like member around in a predetermined route;
A light emitting unit,
Of the light emitted from the light emitting portion, the surface of the sheet member placed on the belt-like member extends between both ends of the belt-like member in the width direction orthogonal to the moving direction of the belt-like member moving around. A light receiving unit that detects emitted light traveling along an optical path extending in a direction intersecting the moving direction along a passing surface;
A detection unit configured to detect floating of the sheet member placed on the belt-like member from the outer peripheral surface by a change in the incident state of the emitted light to the light receiving unit;
The outer periphery at a predetermined position in the circulation path so that the warpage in the band-shaped member in which the outer peripheral surface side is warped in the width direction is suppressed within a range not blocking the light path of the emitted light An urging portion that urges the strip-shaped member in a direction to suppress the warping to the surface side;
It is characterized by having.

The invention according to claim 2 is the transfer apparatus according to claim 1;
The biasing unit biases the band-shaped member in a range including the position of the optical path of the outgoing light in the movement direction.

The invention according to claim 3 is the transfer apparatus according to claim 1 or 2, wherein
The biasing portion is characterized by including a pressing member that presses the strip-shaped member from the outer peripheral surface side.

The invention according to claim 4 is the transfer apparatus according to claim 2;
The biasing unit includes a pressing member configured to press the belt-like member from the outer peripheral surface side,
The pressing member is a member having a light shielding property provided with a light passing portion for passing the emitted light.
The light receiving unit is characterized in that the emitted light which has passed through the light passing unit is detected.

The invention described in claim 5 is the transfer apparatus according to claim 4 in which
The pressing member is a member that contacts the outer peripheral surface of the strip-shaped member and rotates in accordance with the circumferential movement of the strip-shaped member.
The pressing member may be provided with a plurality of the light passing portions that allow the emitted light to pass at different timings according to the rotation of the pressing member.

The invention according to claim 6 is the transfer apparatus according to claim 2 in which
The biasing portion has a light transmitting pressing member for pressing the strip-shaped member from the outer peripheral surface side,
The light receiving unit is characterized in that the emitted light transmitted through the pressing member is detected.

The invention according to claim 7 is the transfer device according to claim 1 or 2;
The urging unit is characterized in that the belt-like member is urged by attracting the belt-like member from the inner peripheral surface side of the belt-like member to exert a force.

The invention according to claim 8 is the transfer apparatus according to any one of claims 1 to 7,
The strip-shaped member is spanned and provided with a plurality of transport rollers for circumferentially moving the strip-shaped member in accordance with the rotation operation.
The drive unit causes the strip member to circulate by rotating at least one of the plurality of transport rollers.
The conveyance device is configured to rotate the rotation shaft of the rotational movement of at least a portion of the plurality of conveyance rollers so as to make the tension at both ends of the belt-like member in the width direction different in the belt-like member moving around. It is characterized in that it comprises a tension adjustment unit that inclines in the width direction.

The invention according to claim 9 is the transfer apparatus according to any one of claims 1 to 8;
The light receiving unit detects a plurality of emitted lights which are emitted from the light emitting unit and traveled through a plurality of the optical paths which are different in distance from the outer peripheral surface of the strip-shaped member,
The detection means detects the ascent according to a change in the incident state of the outgoing light which has traveled a predetermined one of the plurality of optical paths according to the thickness of the sheet member placed on the outer peripheral surface. And
The biasing unit biases the strip-shaped member such that the warp of the strip-shaped member is suppressed within a range not blocking the one optical path.

The invention according to claim 10 is the transfer device according to any one of claims 1 to 8,
A first movement drive unit for moving the light emitting unit and the light receiving unit in a direction in which the distance from the outer peripheral surface of the strip-shaped member changes;
When the detection of the floating is performed by the detection unit, the distance from the outer peripheral surface of the optical path of the emitted light is a predetermined distance according to the thickness of the sheet member placed on the outer peripheral surface. First movement control means for moving the light emitting unit and the light receiving unit by the first movement driving unit;
It is characterized by having.

The invention according to claim 11 is the transfer device according to any one of claims 1 to 10,
The belt-like member is a steel belt.

In order to achieve the above object, the invention of the inkjet recording apparatus according to claim 12 is:
The transport apparatus according to any one of claims 1 to 11,
An ink discharge unit that discharges ink to a sheet member placed on the outer peripheral surface of the belt-like member;
It is characterized by having.

The invention described in claim 13 is the inkjet recording apparatus according to claim 12.
The ink discharge unit discharges the ink on the downstream side of the position of the light path of the emitted light in the conveyance direction of the sheet member by the conveyance device.

The invention according to claim 14 is the inkjet recording apparatus according to claim 13.
A second movement drive unit for moving the ink discharge unit in a direction in which the distance between the ink discharge surface on which the ink is discharged and the outer peripheral surface of the strip-shaped member changes;
Moving the ink discharge unit to a retracted position where the ink discharge surface and the sheet member on which the lift has occurred are not in contact by the second movement driving unit when the floating is detected by the detection unit; 2 movement control means,
Equipped with
The light emitting unit and the light receiving unit are position ranges in which the distance between the ink ejection unit and the light path of the emitted light in the conveyance direction is equal to or longer than a predetermined distance on the upstream side with respect to the ink ejection unit in the conveyance direction. Placed inside
The predetermined distance is a product of a maximum time required for the movement of the ink ejection unit to the retracted position by the second movement driving unit and a movement speed of the circumferential movement of the belt-like member. .

  According to the present invention, there is an effect that floating of the sheet member can be detected more accurately.

FIG. 1 is a view showing a schematic configuration of an inkjet recording apparatus. FIG. 2 is a block diagram showing the main functional configuration of the inkjet recording apparatus. It is a schematic diagram which shows the structure of a medium detection part and an urging | biasing part. It is a figure explaining height adjustment of a head unit, and selection of outgoing radiation light for detection. It is a figure explaining the other method of adjusting the height of emitted light. It is a figure explaining the uneven distribution of a conveyance belt, and its amendment method. It is a figure which shows the other example of the shape of the wheel of an urging | biasing part, and an arrangement position. It is a schematic diagram which shows the structure of the urging | biasing part in the modification 1. FIG. FIG. 13 is a schematic view showing a configuration of a biasing unit in Modification 2;

  Hereinafter, an embodiment according to a transport apparatus and an inkjet recording apparatus of the present invention will be described based on the drawings.

<Configuration of Inkjet Recording Apparatus>
FIG. 1 is a view showing a schematic configuration of an inkjet recording apparatus 1 according to a first embodiment of the present invention.
The inkjet recording apparatus 1 includes a recording medium supply unit 10, an image recording unit 20, a recording medium discharge unit 30, and a control unit 40 (FIG. 2) (detection means, first movement control means, second movement control means ) Etc.

The recording medium supply unit 10 includes a placement tray 11, a medium delivery roller 12, and the like.
The placement tray 11 is a plate-like member on which sheet-like recording media P (sheet members) such as sheets, thick paper, corrugated board material and resin plate can be placed one on top of the other. The recording medium P is sent to the image recording unit 20 in order. The placement tray 11 is movable in the vertical direction, and is held at a position where the uppermost recording medium P is sent to the image recording unit 20 according to the total weight of the placed recording medium P and the like. The recording medium P is not limited to a short medium such as a sheet, but may be a long medium such as roll paper which is unwound and supplied from a roll.
The medium delivery roller 12 is a rotatable roller that holds the recording medium P from above and below, and delivers the recording medium P placed on the top of the placement tray 11 in the horizontal direction here. The medium delivery roller 12 is attached with a guide member for aligning the recording medium P at a predetermined position in the width direction perpendicular to the conveyance direction (left direction in FIG. 1) of the recording medium P. The recording medium P is sent to the image recording unit 20 in a state in which the direction alignment is performed.
A heating unit for heating the recording medium P to a predetermined temperature, a surface treatment unit for reforming the surface of the recording medium P into a state in which the ink is easily fixed, and the like, between the recording medium supply unit 10 and the image recording unit 20 May be provided.

The image recording unit 20 discharges ink onto the recording medium P delivered from the recording medium supply unit 10 to record an image. Further, the image recording unit 20 sends the recording medium P on which the image is recorded to the recording medium discharge unit 30.
The image recording unit 20 includes a conveyance unit 21 having a conveyance belt 211 (strip-like member), a driving roller 212, a driven roller 213, a tension roller 214, and a biasing unit 215, a support suction unit 22, a pressing roller 23, and ink. It includes one or more (here, four) head units 24 (ink ejection units) to be ejected, a medium detection unit 25 that detects floating of the recording medium P, and the like. The drive roller 212, the driven roller 213, and the tension roller 214 in the transport unit 21 all constitute a transport roller.

The conveyance belt 211 of the conveyance unit 21 is an endless (annular) belt-like member that is stretched around the drive roller 212, the driven roller 213, and the tension roller 214, and a steel belt is used here. The steel belt can be made of, for example, stainless steel such as SUS304 and SUS631 with a thickness of about 0.3 mm, an aluminum alloy, or the like. Further, in the conveyance belt 211, holes 211a (FIG. 3) having the same opening shape are formed at equal intervals by penetrating between the outer circumferential surface and the inner circumferential surface of the conveyance belt 211, and the predetermined aperture ratio ( For example, it is provided so as to be 20%, and air can pass through.
The conveyance belt 211 is driven to rotate by the drive roller 212 being driven by the conveyance motor 561 (FIG. 2) (drive unit) attached to the drive roller 212, and the drive roller 212 is driven according to the rotation operation. The roller 213 and the tension roller 214 are circularly moved around. The conveyance unit 21 moves the recording medium P placed on the conveyance belt 211 in the conveyance direction in the conveyance section from the driven roller 213 to the drive roller 212 by the circulation movement operation of the conveyance belt 211, thereby the head unit Let the ink reach the area by 24.

  The tension roller 214 is one of the conveyance rollers, and is a member for applying tension with a predetermined distribution to the conveyance belt 211 in the width direction so that uneven distribution of the conveyance belt 211 described later is corrected. The tension roller 214 is provided so that the rotation axis can be inclined with respect to the width direction, and the rotation axis is inclined by the operation of the conveyance roller inclination drive unit 57 (FIG. 2). Give tension.

  The biasing portion 215 biases the side end portion 211E (FIG. 3B) within a predetermined near range from both ends in the width direction of the conveyance belt 211 toward the inner circumferential surface side of the conveyance belt 211. As described above, when the side edge portion 211E of the conveyance belt 211 is urged by the urging unit 215, and the conveyance belt 211 is warped to the outer peripheral surface side, the recording medium by the medium detection unit 25 described later The light used for float detection of P is not blocked by the transport belt 211. The configuration of the biasing unit 215 will be described in detail later.

  The support suction unit 22 is provided along the inner peripheral surface of the conveyance belt 211, and supports the conveyance belt 211 which slides on the support suction unit 22 and circulates on a flat surface (support surface). In addition, the support suction unit 22 sucks air from the inner peripheral surface side of the conveyance belt 211 through the hole portion 211 a provided in the conveyance belt 211 by the suction fan 511 (FIG. 2), whereby the support suction unit 22 is disposed on the conveyance belt 211. The recording medium P is attracted onto the outer peripheral surface (the mounting surface of the recording medium P) of the transport belt 211.

  The pressure roller 23 is a roller rotatably provided at a position facing the driven roller 213 with the conveyance belt 211 interposed therebetween, and from the outer peripheral surface of the conveyance belt 211 of the recording medium P delivered from the recording medium supply unit 10. In particular, the sheet is pressed (pressed) against the conveying belt 211 with an appropriate pressure and guided along the conveying belt 211 so that curling (rolling up) of the tip end portion is suppressed and suction is more reliably performed. .

  The head unit 24 has a configuration in which recording heads 241 (FIG. 2) that discharge ink are arranged on a surface (ink discharge surface) that faces the outer peripheral surface of the transport belt 211. The head unit 24 ejects the ink from the nozzle opening provided in the recording head 241 on the ink ejection surface at an appropriate timing according to the circumferential movement of the transport belt 211 on which the recording medium P is placed. The image is recorded by landing on the top. In the inkjet recording apparatus 1 of the present embodiment, four head units 24 respectively corresponding to four color inks of yellow (Y), magenta (M), cyan (C), and black (K) are in the conveyance direction of the recording medium P. From the upstream side, they are arranged in the order of Y, M, C, and K in a predetermined interval.

  The head unit 24 is provided with a nozzle opening in a range covering the recordable width of the image on the recording medium P in the width direction orthogonal to the transport direction. The position of the head unit 24 is fixed at the time of recording an image, and the ink is sequentially discharged at predetermined intervals (intervals in the transport direction) at different positions in the transport direction according to the transport of the recording medium P. Record images by single pass method.

The head unit 24 is provided movably in the direction of distance perpendicular to the outer peripheral surface of the transport belt 211. Thus, by adjusting the position of the head unit 24 in the distance direction according to the thickness of the recording medium P to be recorded, the distance between the ink ejection surface of the head unit and the recording medium P can be made constant. Can. In addition, when the medium detection unit 25 detects the floating of the recording medium P, the head unit 24 can be raised and retracted to the retracted position where the ink ejection surface and the recording medium P do not contact.
The configuration of the mechanism for moving the head unit 24 in the distance direction is not particularly limited, but in the present embodiment, a head unit lift motor 531 (stepping motor or servomotor) along a column extending in the distance direction (FIG. The head unit 24 is fixed to a raising and lowering member that moves up and down according to the operation of the (second movement driving unit).
A configuration for fixing these inks on the downstream side of the landing range of the ink from the head unit 24 to the recording medium P, for example, a drying unit for drying a solvent component, and a reaction-solidified UV curable ink An ultraviolet irradiation unit or the like may be further provided.

  Before the recording medium P is conveyed to a position where the recording medium P faces the head unit 24 (the medium detection unit 25 lifts the outer circumference of the recording medium P which is placed on the outer circumference of the conveyance belt 211 and conveyed, That is, detection is performed upstream of the head unit 24 in the transport direction. The medium detection unit 25 includes a light emitting unit 251 (FIG. 3) and a surface through which the surface of the recording medium P placed on the conveyance belt 211 passes in the above-described conveyance section among the light emitted from the light emission unit 251. And a light receiving unit 252 for detecting the emitted light which has traveled a predetermined light path L (traveling path). The detection result of the emitted light by the light receiving unit 252 is output to the control unit 40. Based on the detection result, the control unit 40 can detect the floating based on the change in the incident state of the emitted light on the light receiving unit 252 according to the floating from the outer peripheral surface of the recording medium P. The medium detection unit 25 can also detect the foreign matter when there is a foreign matter having a height blocking the emitted light on the recording medium P. The configuration and operation of the medium detection unit 25 will be described in detail later.

  The recording medium discharge unit 30 holds and holds the recording medium P delivered from the image recording unit 20 until it is taken out by the user. The recording medium discharge unit 30 includes a discharge tray 31 and a guide roller 32. The recording medium P sent from the image recording unit 20 is vertically held by the guide roller 32, conveyed, and placed on the discharge tray 31.

FIG. 2 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1.
The inkjet recording apparatus 1 includes a control unit 40, a support suction unit 22 having a suction control unit 51 and a suction fan 511, a head unit 24 having a head control unit 52 and a recording head 241, and a head unit elevation control unit 53. A head unit lifting motor 531, a medium detection control unit 54, a medium detecting unit 25 having a light emitting unit 251 and a light receiving unit 252, a detecting unit lifting control unit 55, and a detecting unit lifting motor 551 (first movement drive unit) And a conveyance control unit 56, a conveyance motor 561, a conveyance roller inclination drive unit 57 (tension adjustment unit), an input / output interface 58, a bus 59, and the like. Among them, the suction control unit 51, the head control unit 52, the head unit elevation control unit 53, the medium detection control unit 54, the detection unit elevation control unit 55, and the conveyance control unit 56 use the respective hardware configurations of the control unit 40 together. Alternatively, a dedicated CPU, memory or logic circuit may be provided separately. Further, in the inkjet recording apparatus 1 according to the present embodiment, the transport unit 21, the medium detection unit 25, the control unit 40, the detection unit elevation control unit 55, the detection unit elevation motor 551, the conveyance control unit 56, the conveyance motor 561, and the conveyance roller inclination. The drive unit 57 constitutes a conveyance device.

  The control unit 40 includes a CPU 41 (Central Processing Unit), a RAM 42 (Random Access Memory), a ROM 43 (Read Only Memory), and a storage unit 44.

  The CPU 41 reads various control programs and setting data stored in the ROM 43, stores the read control programs and setting data in the RAM 42, executes the program, and performs various arithmetic processing. The CPU 41 also controls the overall operation of the inkjet recording apparatus 1.

  The RAM 42 provides a working memory space to the CPU 41 and stores temporary data. The RAM 42 may include non-volatile memory.

  The ROM 43 stores various control programs executed by the CPU 41, setting data, and the like. Note that instead of the ROM 43, a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

  The storage unit 44 stores a print job (image recording command) input from the external device 2 through the input / output interface 58 and image data of an image to be recorded according to the print job. For example, a hard disk drive (HDD) may be used as the storage unit 44, and a dynamic random access memory (DRAM) may be used in combination.

  The suction control unit 51 causes the suction fan 511 of the support suction unit 22 to rotate at a rotation speed corresponding to the control signal from the control unit 40.

  The head control unit 52 causes the nozzles of the recording head 241 to eject ink by outputting the image data to the head driving unit in the recording head 241 at an appropriate timing according to the control signal from the control unit 40.

  The head unit elevation control unit 53 operates the head unit elevation motor 531 in accordance with the control signal from the control unit 40 to move the head unit 24 in the distance direction.

  The medium detection control unit 54 causes the light emitting unit 251 to emit light in response to the control signal from the control unit 40, and receives the light reception signal from the light receiving unit 252, and relates to the detection result of the emitted light from the light emission unit 251. A signal is output to the control unit 40.

  The detection unit elevation control unit 55 operates the detection unit elevation motor 551 according to the control signal from the control unit 40 to move the light emitting unit 251 and the light reception unit 252 in the medium detection unit 25 in the distance direction.

  The conveyance control unit 56 separately controls the operation of the conveyance motor 561 attached to each of the medium delivery roller 12, the drive roller 212, and the guide roller 32 based on the control signal supplied from the control unit 40 to control each roller. The recording medium P is transported at an appropriate speed by rotating it.

  Based on the control signal supplied from the control unit 40, the conveyance roller inclination drive unit 57 performs a driving operation of inclining the rotation axis of the tension roller 214 in the predetermined direction with respect to the width direction.

  The input / output interface 58 mediates transmission and reception of data between the external device 2 and the control unit 40. The input / output interface 58 is formed of, for example, various serial interfaces, any of various parallel interfaces, or a combination thereof.

  The bus 59 is a path for transmitting and receiving signals between the control unit 40 and other components.

  The external device 2 is, for example, a personal computer, and supplies a print job, image data, and the like to the control unit 40 via the input / output interface 58.

<Configuration and Operation of Medium Detection Unit>
Next, the configuration and operation of the medium detection unit 25 in the image recording unit 20 will be described.
FIG. 3 is a schematic view showing the configuration of the medium detection unit 25 and the urging unit 215. As shown in FIG.
FIG. 3A is a plan view of a portion of the image recording unit 20 provided with the medium detection unit 25 and the urging unit 215 as viewed from above the outer peripheral surface of the conveyance belt 211 (from the positive direction of the distance). is there.
FIG.3 (b) is a figure which shows a cross section perpendicular | vertical to the conveyance direction in the AA in FIG. 3 (a).
FIG. 3C is a view of the medium detection unit 25 and the urging unit 215 as viewed from the side (from the negative direction in the width direction).

As shown in FIG. 3A, the medium detection unit 25 has a light emitting unit 251 disposed on the negative side in the width direction relative to the outer peripheral surface of the transport belt 211 and a width direction than the outer peripheral surface of the transport belt 211. And a light receiving unit 252 disposed to face the light emitting unit 251 on the negative direction side.
The light emitting unit 251 emits light having high directivity and traveling along a linear optical path, for example, laser light, from the light emitting element 2511. The optical path L of the light emitted from the light emitting unit 251 is a path along the outer peripheral surface extending in the width direction across the both ends of the transport belt 211 in the width direction in the transport section of the recording medium P. Further, as shown in FIGS. 3B and 3C, the light emitting unit 251 is provided with a plurality of (four in this case) light emitting elements 2511 at equal intervals along the distance direction. The plurality of light emitting elements 2511 emit a plurality of emitted lights traveling along a plurality of optical paths L parallel to each other in the distance direction at equal intervals. In FIG. 3B, only one optical path L among the plurality of optical paths L is drawn by a broken line in order to avoid difficulty in viewing.
In the light receiving unit 252, a plurality of (here, four) light receiving elements 2521 that receive emitted light from the plurality of light emitting elements 2511 of the light emitting unit 251 and detect the intensity of the emitted light are a plurality of light emitting elements 2511 It is provided corresponding to
The number and the arrangement interval of the light emitting elements 2511 in the light emitting unit 251, and the number and the arrangement interval of the light receiving elements 2521 in the light receiving unit 252 are not limited to the above. In addition, the light path L of the emitted light is not limited to a path parallel to the width direction, and may extend in another direction intersecting the transport direction. Alternatively, a light blocking member provided with a slit may be disposed on the front surface of the light emitting element 2511 of the light emitting unit 251 to block light scattered from the light emitting element 2511 in a direction other than the light path L.

When the recording medium P placed and conveyed on the outer peripheral surface of the conveyance belt 211 is floating from the outer peripheral surface, the height of the floating height from the outer peripheral surface among the light emitted from the plurality of light emitting elements 2511 The light traveling along the optical path L within the range is blocked by the recording medium P, and the detection value by the light receiving element 2521 that detects the light changes. The floating of the recording medium P from the outer peripheral surface of the conveyance belt 211 is detected based on the change of the detection value (that is, the change of the incident state to the light receiving unit 252).
More specifically, among the plurality of emitted lights described above, one emitted light is selected in advance as the light to be detected, such that the distance d2 in the distance direction from the surface of the recording medium P satisfies the predetermined distance condition, The detection value of the emitted light of the detection target is used for detection of floating. Here, the predetermined distance condition may be that the distance from the surface of the recording medium P to the optical path L is equal to or less than a predetermined reference distance and the optical path L farthest from the surface of the recording medium P. . The reference distance is set to a value smaller than the distance d1 by providing a predetermined safety zone with respect to the distance d1 in the distance direction between the surface of the recording medium P and the ink ejection surface 24a of the head unit 24. In the present embodiment, the distance d1 is about 1 mm, and the reference distance is set to 0.5 mm with a safety margin of 0.5 mm for the distance d1.

  In the inkjet recording apparatus 1 of the present embodiment, the height of the head unit 24 is set so that the distance from the surface of the recording medium P to the ink ejection surface 24a is constant at the distance d1 regardless of the thickness of the recording medium P being conveyed. Is adjusted. Further, in accordance with the adjustment of the height of the head unit 24, the emitted light of the detection target used for the detection of the floating of the recording medium P is changed. The thickness of the recording medium P may be acquired from the detection result of the height of the surface of the recording medium P by a contact sensor or a distance sensor (not shown), or acquired based on the type of the recording medium P designated by the print job. It may be done.

  FIG. 4 is a diagram for explaining the height adjustment of the head unit 24 and the selection of the emitted light to be detected. Hereinafter, the four light emitting elements 2511 in the light emitting unit 251 will be referred to as light emitting elements 2511 a to 2511 d in order from the closest distance from the outer circumferential surface of the conveyance belt 211.

FIG. 4A shows an example in which the recording medium P having a thickness equal to or less than a predetermined standard value is conveyed. In this case, the light emitted from the light emitting element 2511 a provided at the lowermost position in the light emitting unit 251 satisfies the above distance condition, and the light is selected as the light to be detected.
FIG. 4B shows an example in which the recording medium P having a thickness larger than the standard value described above is transported. In this case, the head unit elevating motor 531 operates under the control of the head unit elevating control unit 53, whereby the distance between the ink discharge surface 24a and the surface of the recording medium P becomes the distance d1. Move up to the position. Further, in this example, the light emitted from the light emitting element 2511 b provided second from the bottom in the light emitting unit 251 satisfies the above distance condition, and the light is selected as the light to be detected.
In the present embodiment, the light emitting elements 2511 and the light receiving elements 2521 are arranged to a position higher than the ink ejection surface 24 a when the head unit 24 is disposed at the highest position where ink ejection to the recording medium P is possible. There is. As a result, regardless of the position at which the head unit 24 discharges ink, it is possible to perform floating detection by selecting emitted light of an appropriate height as a detection target.

  When the medium detection unit 25 detects floating of the recording medium P, as shown in FIG. 4C, the head unit elevation motor 531 operates according to the control by the head unit elevation control unit 53. The position of the head unit 24 moves upward to a predetermined retraction position where the distance between the ink ejection surface 24 a and the outer peripheral surface of the transport belt 211 is the distance d3. Here, the distance d3 is set larger than the height (the distance from the outer peripheral surface) at which the rising of the recording medium P is restricted by a pressing member (not shown). Therefore, the retracted position is a position at which the ink ejection surface 24 a does not contact the recording medium P in which the floating occurs.

  In the present embodiment, after the medium detection unit 25 detects the floating of the recording medium P, the head unit 24 moves to the retracted position before the floating detection portion moves to the position facing the head unit 24. To complete, the positions of the light emitting unit 251 and the light receiving unit 252 of the medium detection unit 25 (more specifically, the distance d4 in the transport direction between the head unit 24 and the light emitting element 2511 and the light receiving element 2521) are determined. ing. That is, the light emitting unit 251 and the light receiving unit 252 are disposed at positions as close as possible to the head unit 24 within a position range that is separated from the head unit 24 by a predetermined distance or more upstream in the transport direction. However, the time required to move from the position closest to the outer peripheral surface of the transport belt 211 to the retracted position (that is, the maximum time required for the head unit 24 to move to the retracted position) It is determined by the product of

The configuration for changing the height of the emitted light to be detected is not limited to that shown in FIG.
For example, as shown in FIGS. 5A and 5B, the distance from the outer peripheral surface of the optical path L of the emitted light corresponds to the increase in the thickness of the recording medium P mounted on the outer peripheral surface. The light emitting unit 251 and the light receiving unit 252 of the medium detection unit 25 may be moved in the distance direction so as to increase gradually. The movement of the light emitting unit 251 and the light receiving unit 252 in the distance direction is performed by the operation of the detection unit elevation motor 551 according to the control by the detection unit elevation control unit 55. In this case, the number of light emitting elements 2511 provided in the light emitting unit 251 and the number of light receiving elements 2521 provided in the light receiving unit 252 can be reduced according to the movable range of the light emitting unit 251 and the light receiving unit 252. . For example, one light emitting element 2511 and one light receiving element 2521 may be provided, and the light emitting unit 251 and the light receiving unit 252 may be moved in the distance direction such that the height of the emitted light is an appropriate height according to the recording medium P. be able to.

<Correction of uneven distribution of conveyance belt>
Here, correction of uneven distribution of the conveyance belt 211 will be described.
In the transport belt 211 that is looped and moved across the drive roller 212, the driven roller 213, and the tension roller 214, the distribution of the force that the transport belt 211 receives from each of the transport rollers is uneven due to, for example, the width direction. The contact range of the conveyance belt 211 in the conveyance roller may be shifted in the axial direction of the conveyance roller, which may cause a problem that the conveyance belt 211 is unevenly distributed in the width direction. This uneven distribution is also called meandering of the transport belt 211.

FIG. 6 is a view for explaining the uneven distribution of the transport belt 211 and the correction method thereof. In FIG. 6, the periphery of the tension roller 214 in the transport belt 211 is shown.
FIG. 6A shows an example in which the position of the conveyance belt 211 in the width direction is shifted, and the conveyance belt 211 is unevenly distributed on the side of one end 214 a of the tension roller 214 in the width direction. .

  When correcting such uneven distribution of the transport belt 211, the end portion 214a of the tension roller 214 is directed to the outside of the circumferential path of the transport belt 211 so that the tension at both ends in the width direction of the transport belt 211 is different. Urge (press or pull). In the present embodiment, as shown by the graph in the lower part of FIG. 6A, the distribution of tension in the width direction is such that the tension at the one end 214 a of the tension roller 214 becomes the highest. The end portion 214 a of the tension roller 214 is biased. The biasing can be performed by an operation of tilting the rotation shaft of the tension roller 214 with respect to the width direction by the transport roller tilt drive unit 57 under the control of the control unit 40.

As described above, as shown in FIG. 6B, by making the tension at both ends of the conveyance belt 211 different in the width direction, the contact range of the conveyance belt 211 at the tension roller 214 is different from that at the other side of the tension roller 214. In order to move toward the end 214b, uneven distribution of the transport belt 211 is corrected.
The correction of the uneven distribution of the conveyance belt 211 may be performed by inclining the conveyance rollers other than the tension roller 214, that is, the rotation shafts of the driving roller 212 and the driven roller 213. Further, the direction in which the transport roller is biased may be any direction as long as it is directed to the outside of the circulation path.

  In such a correction of uneven distribution of the transport belt 211, a larger tension is applied to the transport belt 211, that is, a force in the direction of increasing the circumferential length of the transport belt 211 is applied closer to the end in the width direction of the transport belt 211. For this reason, in the conveyance belt 211, the curvature to the outer peripheral surface side may arise in the width direction by application of the tension in correction | amendment of uneven distribution of the conveyance belt 211. As shown in FIG. The warp of the conveyance belt 211 is particularly likely to occur at the side end portion 211E within a predetermined proximity range from the end in the width direction. In addition, such a warp particularly occurs in the conveyance belt 211 configured by a member having plasticity, that is, a member having a property that remains distorted even if the external force is removed according to the external force as in the steel belt of the present embodiment. Cheap.

<Configuration and Operation of Actuating Section>
Next, the configuration and operation of the biasing unit 215 in the transport unit 21 of the image recording unit 20 will be described with reference to FIG.

As described above, when the transport belt 211 is circulated while the side end portion 211E (FIG. 3B) of the transport belt 211 is warped toward the outer peripheral surface side, the light paths L (a plurality of In the optical path L, the side end portion 211E of the transport belt 211 blocks the optical path L of the outgoing light selected as the detection target, and the floating of the recording medium P can not be accurately detected. Problems arise.
Therefore, in the present embodiment, the side end 211E is located at a predetermined position in the conveyance section of the recording medium P so that the warpage of the side end 211E is suppressed within the range not blocking the optical path L of the outgoing light. An urging portion 215 is provided which urges in a direction in which the warpage toward the outer peripheral surface side is suppressed (that is, toward the inner peripheral surface side of the transport belt 211).

  As shown in FIGS. 3 (a) to 3 (c), the biasing unit 215 is provided with a wheel 215a (pressing member) rotating about a shaft 215b, and a shaft 215b, and the shaft 215b and a support suction unit And a fixing portion 215c fixed to the side surface of the support suction portion 22 of the transport unit 21 so that the positional relationship with the position 22 is fixed. The fixing portion 215c may be fixed to another gantry, a housing, or the like in which the relative position to the support suction portion 22 is fixed.

  The wheel 215a of the biasing portion 215 is in contact with the outer peripheral surface of the conveyance belt 211 from the upper side and is urged toward the inner peripheral surface within the range of the side end portion 211E in the width direction, and friction with the outer peripheral surface. The force rotates according to the circumferential movement of the transport belt 211. The wheel 215a is preferably provided at such a height that it does not contact the outer peripheral surface of the conveyance belt 211 when the side end portion 211E of the conveyance belt 211 is not warped. If the height of the emitted light from the outer peripheral surface is extremely low and it is desired to suppress the warpage of the side end 211E as much as possible, the height at which the outer end face contacts the outer peripheral surface regardless of the warpage of the side end 211E as necessary. It may be provided.

  The two urging portions 215 are provided on both sides in the width direction of the conveyance belt 211. The two urging units 215 provided on the light emitting unit 251 side of the conveyance belt 211 are provided at two places sandwiching the optical path L in the conveyance direction in the vicinity of the optical path L of the light emitted from the light emission unit 251. Similarly, the two urging units 215 provided on the light receiving unit 252 side of the conveyance belt 211 are provided at two places sandwiching the light passage L in the conveyance direction in the vicinity of the light passage L of the outgoing light entering the light receiving unit 252 It is done. In addition, in each urging unit 215, the wheel 215a, the shaft 215b, and the fixing unit 215c are all provided at positions that do not block the optical path L of the emitted light.

The shape and arrangement position of the wheel 215a of the biasing portion 215 are not limited to the above.
For example, as shown in FIG. 7A, slits S (light passing portions) extending along the radial direction of the wheel 215a and passing light are provided in the wheel 215a, and they differ from each other according to the rotation of the wheel 215a The urging unit 215 may be disposed at a position where the light emitted from the light emitting unit 251 passes through the slit S at the timing. In this case, the floating detection may be performed based on the detection value of the outgoing light by the light receiving unit 252 within a period in which the outgoing light passes through the slit S. The slit S may be a light passage hole penetrating the wheel 215a as shown in FIG. 7A, or may be a notch provided from the outer periphery of the wheel 215a toward the center.
Further, as shown in FIG. 7B, the wheel 215a is made of a light transmitting member, and the urging portion 215 is disposed at a position where the light emitted from the light emitting portion 251 passes through the wheel 215a. May be

(Modification 1)
Then, the modification 1 of the said embodiment is demonstrated. The present modification is different from the above embodiment in the configuration of the biasing unit 215. Below, the difference with the said embodiment is demonstrated.

FIG. 8 is a schematic view showing the configuration of the urging unit 215 in the present modification.
FIG. 8A is a plan view of the portion of the image recording unit 20 provided with the medium detection unit 25 and the urging unit 215 as viewed from above the outer peripheral surface of the conveyance belt 211.
FIG. 8 (b) is a view showing a cross section perpendicular to the transport direction at line B-B in FIG. 8 (a).

The biasing portion 215 of this modification is formed of a bowl-shaped guide member 215 d (pressing member). The guide member 215d extends in the width direction to a position where the guide member 215d is fixed to the side surface of the support suction portion 22 and extends in the distance direction, and the upper end of the first portion is broken in the width direction. And the existing second part. The guide member 215d abuts the outer peripheral surface of the side end portion 211E of the conveyance belt 211 at the lower surface of the second portion, and biases the side end portion 211E where the warpage occurs to the inner peripheral surface side. Further, the guide member 215d is provided at a position overlapping the light path L of the light emitted from the light emitting unit 251 in the transport direction, and the height of the second portion is set to be lower than the height of the light path L. ing. Also by the biasing portion 215 having the configuration of the present modification as described above, the side end portion 211E of the transport belt 211 can be biased to suppress the warp without blocking the light path L of the emitted light.
The configuration and arrangement of the guide member 215d are not limited to the above as long as the side end portion 211E of the conveyance belt 211 can be biased so as not to block the optical path L of the emitted light. For example, the guide member 215d may be formed of a light transmitting member, and the guide member 215d (biasing portion 215) may be disposed at a position where the light emitted from the light emitting unit 251 transmits the guide member 215d.

(Modification 2)
Then, the modification 2 of the said embodiment is demonstrated. The present modification is different from the above embodiment in the configuration of the biasing unit 215. Below, the difference with the said embodiment is demonstrated.

FIG. 9 is a schematic view showing the configuration of the biasing unit 215 in the present modification.
FIG. 9A is a plan view of the portion of the image recording unit 20 provided with the medium detection unit 25 and the urging unit 215 as viewed from above the outer peripheral surface of the conveyance belt 211.
FIG.9 (b) is a figure which shows a cross section perpendicular | vertical to the conveyance direction in the CC line in FIG. 9 (a).

  In the present modification, the transport belt 211 is formed of a magnetic substance attracted by a magnet. Further, the biasing portion 215 of this modification covers the magnet 215 e embedded in the portion of the support surface of the support suction portion 22 facing the inner peripheral surface of the side end portion 211 E of the transport belt 211 and the magnet 215 e And the coating layer 215f. The coating layer 215 f is provided for causing the circumferentially moving transport belt 211 to slide smoothly on the biasing portion 215, and is configured by a member having a small coefficient of friction with the transport belt 211. The magnet 215 e and the coating layer 215 f are provided at positions overlapping the light path L of the light emitted from the light emitting unit 251 in the transport direction.

  The biasing portion 215 of this modification attracts the side end portion 211E of the magnetic material conveyance belt 211 from the inner peripheral surface side by the magnet 215e and exerts a force on the side end portion 211E. Energize to the circumferential side. Also by the biasing portion 215 having the configuration of the present modification as described above, the side end portion 211E of the transport belt 211 can be biased to suppress the warp without blocking the light path L of the emitted light. In particular, since all the components are located on the inner peripheral surface side of the conveyance belt 211 in the urging unit 215 of this modification, there is no concern that the light emitted from the light emitting unit 251 is blocked by the urging unit 215. In addition, since the outer peripheral surface of the conveyance belt 211 is not directly pressed, the occurrence of a defect in which the outer peripheral surface is twisted or damaged by the pressure is suppressed.

As described above, the conveyance device according to the above embodiment includes the conveyance belt 211 on which the recording medium P is placed on the outer peripheral surface, the conveyance motor 561 that circumferentially moves the conveyance belt 211 along the predetermined circulation path, and the light emitting unit A recording medium P placed on the transport belt 211 across the both ends of the transport belt 211 in the width direction orthogonal to the moving direction of the transport belt 211 moving among the light emitted from the light emitting unit 251 and the light emitting unit 251. The light receiving unit 252 detects the emitted light traveling along the optical path extending in the direction intersecting the moving direction along the surface through which the surface of the light passes, and the change in the incident state of the emitted light to the light receiving unit 252 The control unit 40 as a detection unit that detects the floating of the recording medium P placed on the outer peripheral surface, and the conveyance belt 211 in which the outer peripheral surface is warped in the width direction The biasing portion biases the transport belt 211 in a direction to suppress the warpage toward the outer peripheral surface at a predetermined position in the circulation path so that the warpage is suppressed within the range not blocking the light path L of the emitted light 215 is provided.
According to such a configuration, it is possible to prevent the optical path of the light emitted from the light emitting unit 251 from being blocked by the conveyance belt 211 when the conveyance belt 211 warped to the outer peripheral surface side is moved circumferentially. As a result, it is possible to suppress the occurrence of the problem that the floating of the recording medium P is erroneously detected due to the blocking of the emitted light by the conveyance belt 211. Therefore, according to the present embodiment, the floating of the recording medium can be detected more accurately.

  Further, the biasing unit 215 biases the transport belt 211 in a range including the position of the light path L of the outgoing light in the transport direction. As a result, the transport belt 211 can be deformed so that the transport belt 211 does not block the light path L of the emitted light more reliably.

  Further, the urging unit 215 includes a wheel 215a (in the first modification, a guide member 215d) as a pressing member for pressing the conveyance belt 211 from the outer peripheral surface side. By pressing the transport belt 211 from the outer peripheral surface side in this manner, the transport belt 211 can be reliably deformed to the inner peripheral surface side so that the transport belt 211 does not block the optical path L of the emitted light.

  The wheel 215a is a member having a light shielding property provided with a slit S for passing the emitted light, and the light receiving unit 252 detects the emitted light which has passed through the slit S provided in the pressing member. As described above, by providing the slits S in the wheel 215a to allow the emitted light to pass, it is possible to improve the degree of freedom concerning the shape and the arrangement position of the wheel 215a. Therefore, for example, since the wheel 215a can be disposed at the position of the light path L of the outgoing light in the carrying direction, the carrying belt 211 can be deformed so as not to block the light path L of the outgoing light more reliably. .

  The wheel 215a is a member that abuts on the outer circumferential surface of the conveyance belt 211 and rotates according to the circumferential movement of the conveyance belt 211, and the wheel 215a exits at different timings according to the rotation of the wheel 215a. A plurality of slits S are provided for transmitting the emitted light respectively. According to such a configuration, when the wheel 215a is disposed at a position that falls on the optical path L of the outgoing light, the outgoing light passes through the slit S every predetermined period, so that the light reception at the timing when the outgoing light passes through the slit S The floating of the recording medium P can be detected based on the detection result of the outgoing light by the unit 252.

  In addition, the wheel 215a is light transmissive, and the light receiving unit 252 detects the emitted light transmitted through the wheel 215a. Also with such a configuration, the wheel 215a can be disposed at the position of the optical path L of the outgoing light in the transport direction. Thereby, the conveyance belt 211 can be deformed so that the conveyance belt 211 does not intercept the light path L of the emitted light.

  Further, the urging unit 215 having the magnet 215e in the second modification urges the conveyance belt 211 by attracting the conveyance belt 211 from the inner peripheral surface side and exerting a force. According to such a configuration, since the biasing portion 215 can be provided on the inner peripheral surface side of the transport belt 211, the optical path L of the emitted light along the outer peripheral surface of the transport belt 211 is blocked by the biasing portion 215. Can be suppressed. Further, since the outer peripheral surface of the transport belt 211 is not directly pressed, it is possible to suppress the occurrence of a defect in which the outer peripheral surface is twisted or damaged by the pressure.

  Further, the conveyance device of the present embodiment includes a drive roller 212, a driven roller 213, and a tension roller 214, which move the conveyance belt 211 in a circulating manner according to the rotation operation when the conveyance belt 211 is stretched. The rotation of the drive roller 212 causes the conveyor belt 211 to rotate, and the conveyor causes the conveyor belt 211 to move in a circumferential direction so that the tension at the opposite ends of the conveyor belt 211 in the width direction becomes different. The conveyance roller inclination drive part 57 which inclines the rotation axis of the rotation operation in the direction of the width is provided. According to such a configuration, when the uneven distribution of the conveyance belt 211 occurs, the uneven distribution can be easily corrected and the conveyance belt 211 can be circulated along an appropriate path. Further, when the transport belt 211 is warped to the outer peripheral surface side due to the correction of uneven distribution, the optical path of the light emitted from the light emitting unit 251 is transported by urging the transport belt 211 to the inner peripheral surface side by the biasing unit 215 It is possible to suppress the occurrence of a defect blocked by the belt 211.

  Further, the light receiving unit 252 detects a plurality of emitted light beams emitted from the light emitting unit 251 and traveled through a plurality of light paths L different in distance from the outer peripheral surface of the transport belt 211. The control unit 40 detects a plurality of light paths L Among the above, floating is detected by a change in the incident state of the outgoing light which has traveled through a predetermined optical path L according to the thickness of the recording medium P placed on the outer peripheral surface (detection means). In this case, the conveyor belt 211 is biased such that the warp of the conveyor belt 211 is suppressed within the range not blocking the one optical path. Thus, without adjusting the heights of the light emitting unit 251 and the light receiving unit 252, that is, the height of the light path L of the emitted light, the floating of the recording medium P is detected at an appropriate height corresponding to the thickness of the recording medium P. can do.

  Further, the conveyance device of the present embodiment includes a detection unit elevating motor 551 that moves the light emitting unit 251 and the light receiving unit 252 in the direction in which the distance from the outer peripheral surface of the conveyance belt 211 changes. When detection of floating by 25 is performed, the detection unit is moved up and down so that the distance from the outer peripheral surface of the optical path L of the emitted light is a predetermined distance according to the thickness of the recording medium P mounted on the outer peripheral surface. The light emitting unit 251 and the light receiving unit 252 are moved by the motor 551 (first movement control means). According to such a configuration, it is possible to perform floating detection at an appropriate height with respect to the recording media P with different thicknesses by using less emitted light. Therefore, the configurations of the light emitting unit 251 and the light receiving unit 252 can be simplified.

  Further, a steel belt is used for the transport belt 211. In such a configuration, since the transport belt 211 has plasticity, warpage is particularly likely to occur. However, by biasing the transport belt 211 by the biasing unit 215, the optical path of the light emitted from the light emitting unit 251 is the transport belt 211. It is possible to effectively suppress the occurrence of the obstruction problem.

  In addition, the inkjet recording apparatus of the present embodiment includes the above-described conveyance device, and a head unit 24 that discharges ink to the recording medium P placed on the outer circumferential surface of the conveyance belt 211. According to such a configuration, the floating of the recording medium P can be accurately detected, and various operations performed on the recording medium P on the outer peripheral surface can not be appropriately performed due to the floating of the recording medium P Can be suppressed.

  In addition, the head unit 24 discharges the ink on the downstream side of the position of the light path L of the emitted light in the transport direction. According to such a configuration, by taking measures such as retraction of the head unit 24 and stop of conveyance according to the detection of the floating, the landing position of the ink on the recording medium P is shifted due to the floating of the recording medium P, and the image quality is improved. Or the ink discharge surface 24a of the head unit 24 comes in contact with the floating recording medium P, and the occurrence of a problem that the ink discharge surface 24a is soiled and the normal ink discharge can not be performed can be suppressed. .

  The ink jet recording apparatus 1 further includes a head unit raising and lowering motor 531 for moving the head unit 24 in the direction in which the distance between the ink ejection surface 24 a and the outer peripheral surface of the transport belt 211 changes. The head unit lift motor 531 moves the head unit 24 to a retracted position where the ink ejection surface 24a does not contact the recording medium P where the floating has occurred (second And the light-emitting unit 251 and the light-receiving unit 252, the distance between the head unit 24 and the light path L of the outgoing light in the carrying direction becomes a predetermined distance or more on the upstream side of the head unit 24 in the carrying direction. It is disposed within the position range, and the predetermined distance is determined by the head unit lifting motor 531. A maximum time required to move to the retracted position of the unit 24, which is the product of the moving speed in the circulation of the conveyance belt 211. According to such a configuration, when floating of the recording medium P is detected during conveyance of the recording medium P, the head unit can be reliably made before the raised recording medium P contacts the ink ejection surface 24 a of the head unit 24. 24 can be retracted to the retraction position. As a result, it is possible to reliably suppress the occurrence of the problem that the ink discharge surface 24a is stained by the floating recording medium P and the normal ink discharge can not be performed.

The present invention is not limited to the above embodiment and each modification, and various modifications are possible.
For example, in the above-described embodiment and the modifications, the example in which only the side end portion 211E of the conveyance belt 211 is along the outer peripheral surface side has been described, but the present invention is not limited thereto. For example, the present invention is applied to a conveyance device that conveys the recording medium P by the conveyance belt 211 that is warped to the vicinity of the center in the width direction, such as when the entire conveyance belt 211 follows an arch in the width direction. May be Further, the position in the width direction in which the conveyance belt 211 is urged by the urging unit 215 is not limited to the range of the side end 211 E as long as the warpage toward the outer peripheral surface of the conveyance belt 211 can be suppressed. It may be a position closer to the center in the width direction than 211E.

  In the embodiment and the modifications described above, when the medium detection unit 25 detects lifting, the head unit 24 is retracted upward to avoid contact between the recording medium P and the ink ejection surface 24 a. As described above, instead of this, the circumferential movement of the transport belt 211 may be stopped when the floating is detected. In this case, the light emitting unit 251 and the light receiving unit 252 of the medium detecting unit 25 move the head by such a distance that the movement of the recording medium P can be stopped before reaching the position where the floating detection point faces the head unit 24. Preferably, it is provided upstream of the unit 24.

In the embodiment and the modifications described above, the medium detection unit 25 performs float detection on the upstream side of the head unit 24 in the transport direction, but the position where the medium detection unit 25 is provided is not limited thereto. .
For example, when a long recording medium such as roll paper is adsorbed to the outer peripheral surface of the conveyance belt 211 and conveyed, and peeled off at the downstream side of the head unit 24, the medium on the downstream side of the head unit 24 in the conveyance direction The peeling state of the recording medium may be detected by detecting the floating of the recording medium P by providing the detection unit 25 and the urging unit 215.
Further, in the ink jet recording apparatus, the recording medium P is conveyed while being delivered among the plurality of conveyance belts, and the recording medium P on each of the conveyance belts performs different processing mutually, any conveyance belt among the plurality of conveyance belts The medium detection unit 25 and the urging unit 215 may be provided correspondingly to the detection of the floating of the recording medium P.

  In each of the above embodiments, the single-pass type inkjet recording apparatus 1 has been described as an example, but the present invention may be applied to an inkjet recording apparatus that performs recording of an image while scanning a recording head.

  Although some embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, but includes the scope of the invention described in the claims and the equivalents thereof. .

Reference Signs List 1 inkjet recording apparatus 10 recording medium supply unit 20 image recording unit 21 conveyance unit 211 conveyance belt 211 E side end portion 211 a hole portion 212 drive roller 213 driven roller 214 tension roller 215 urging portion 215 a wheel 215 b shaft 215 c fixed portion 215 d guide member 215 e Magnet 215f Coating layer 22 Support suction unit 23 Press roller 24 Head unit 24a Ink ejection surface 25 Medium detection unit 251 Light emitting unit 2511 Light emitting unit 252 Light receiving unit 2521 Light receiving unit 30 Recording medium discharge unit 40 Control unit 53 Head unit elevation control unit 531 Head Unit lifting motor 54 Medium detection control unit 55 Detection unit lifting control unit 551 Detection unit lifting motor 56 Transport control unit 561 Transport motor 57 Transport roller inclination drive unit L Optical path P Recording medium S Slip

Claims (14)

A conveying device for conveying a sheet member, wherein
A belt-like member on which the sheet member is placed on the outer peripheral surface;
A drive unit for moving the belt-like member around in a predetermined route;
A light emitting unit,
Of the light emitted from the light emitting portion, the surface of the sheet member placed on the belt-like member extends between both ends of the belt-like member in the width direction orthogonal to the moving direction of the belt-like member moving around. A light receiving unit that detects emitted light traveling along an optical path extending in a direction intersecting the moving direction along a passing surface;
A detection unit configured to detect floating of the sheet member placed on the belt-like member from the outer peripheral surface by a change in the incident state of the emitted light to the light receiving unit;
The outer periphery at a predetermined position in the circulation path so that the warpage in the band-shaped member in which the outer peripheral surface side is warped in the width direction is suppressed within a range not blocking the light path of the emitted light An urging portion that urges the strip-shaped member in a direction to suppress the warping to the surface side;
A transport apparatus comprising:   The transport device according to claim 1, wherein the biasing unit biases the band-shaped member in a range including the position of the light path of the outgoing light in the movement direction.   The conveyance device according to claim 1, wherein the biasing unit includes a pressing member configured to press the band-shaped member from the outer peripheral surface side. The biasing unit includes a pressing member configured to press the belt-like member from the outer peripheral surface side,
The pressing member is a member having a light shielding property provided with a light passing portion for passing the emitted light.
The conveyance device according to claim 2, wherein the light receiving unit detects the emitted light that has passed through the light passing unit. The pressing member is a member that contacts the outer peripheral surface of the strip-shaped member and rotates in accordance with the circumferential movement of the strip-shaped member.
The conveyance device according to claim 4, wherein the pressing member is provided with a plurality of the light passing portions that allow the emitted light to pass at different timings according to the rotation of the pressing member. The biasing portion has a light transmitting pressing member for pressing the strip-shaped member from the outer peripheral surface side,
The conveyance device according to claim 2, wherein the light receiving unit detects the outgoing light transmitted through the pressing member.   The transport device according to claim 1, wherein the biasing unit biases the strip-shaped member by attracting the strip-shaped member from an inner peripheral surface side of the strip-shaped member to exert a force. The strip-shaped member is spanned and provided with a plurality of transport rollers for circumferentially moving the strip-shaped member in accordance with the rotation operation.
The drive unit causes the strip member to circulate by rotating at least one of the plurality of transport rollers.
The conveyance device is configured to rotate the rotation shaft of the rotational movement of at least a portion of the plurality of conveyance rollers so as to make the tension at both ends of the belt-like member in the width direction different in the belt-like member moving around. The conveyance control device according to any one of claims 1 to 7, further comprising: a tension adjustment unit configured to incline with respect to the width direction. The light receiving unit detects a plurality of emitted lights which are emitted from the light emitting unit and traveled through a plurality of the optical paths which are different in distance from the outer peripheral surface of the strip-shaped member,
The detection means detects the ascent according to a change in the incident state of the outgoing light which has traveled a predetermined one of the plurality of optical paths according to the thickness of the sheet member placed on the outer peripheral surface. And
The said biasing part biases the said strip-shaped member so that the curvature of the said strip-shaped member may be suppressed in the range which does not interrupt the said 1st optical path. The conveyance apparatus as described in. A first movement drive unit for moving the light emitting unit and the light receiving unit in a direction in which the distance from the outer peripheral surface of the strip-shaped member changes;
When the detection of the floating is performed by the detection unit, the distance from the outer peripheral surface of the optical path of the emitted light is a predetermined distance according to the thickness of the sheet member placed on the outer peripheral surface. First movement control means for moving the light emitting unit and the light receiving unit by the first movement driving unit;
The transport apparatus according to any one of claims 1 to 8, comprising:   The transport device according to any one of claims 1 to 10, wherein the belt-like member is a steel belt. The transport apparatus according to any one of claims 1 to 11,
An ink discharge unit that discharges ink to a sheet member placed on the outer peripheral surface of the belt-like member;
An inkjet recording apparatus comprising:   The ink jet recording apparatus according to claim 12, wherein the ink discharge unit discharges the ink downstream of the position of the light path of the emitted light in the conveyance direction of the sheet member by the conveyance device. A second movement drive unit for moving the ink discharge unit in a direction in which the distance between the ink discharge surface on which the ink is discharged and the outer peripheral surface of the strip-shaped member changes;
Moving the ink discharge unit to a retracted position where the ink discharge surface and the sheet member on which the lift has occurred are not in contact by the second movement driving unit when the floating is detected by the detection unit; 2 movement control means,
Equipped with
The light emitting unit and the light receiving unit are position ranges in which the distance between the ink ejection unit and the light path of the emitted light in the conveyance direction is equal to or longer than a predetermined distance on the upstream side with respect to the ink ejection unit in the conveyance direction. Placed inside
The predetermined distance is a product of a maximum time required for the movement of the ink ejection unit to the retraction position by the second movement driving unit and a movement speed of the belt-like member in the circumferential movement. The inkjet recording device according to claim 13.

Images