JP2017128024A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording device which can suppress or prevent skew of a recording medium while reducing a possibility of giving damage to the recording medium with a simple configuration.SOLUTION: An ink jet printer includes: a winding shaft 5 around which a recording sheet K before printing is wound and which is freely rotatable; a winding motor 6 which is connected to the winding shaft 5 and rotates the winding shaft 5 in a direction of winding the recording sheet K; and a control device 7 which controls the rotation operation of the winding motor 6 and the operation of a roller drive unit 3, respectively. The control device 7 is configured to execute skew correction processing of rewinding the recording sheet K backward by controlling the winding motor 6 after feeding the recording sheet K frontward by a prescribed amount by a grid roller 1 by controlling the roller drive unit 3 in a state where the winding motor 6 is stopped.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an ink jet recording apparatus that performs printing on a recording medium.

  2. Description of the Related Art Conventionally, there is known an ink jet printer that performs printing using a recording medium wound in a roll shape around a feeding roller (also referred to as a feeding roller) (see, for example, Patent Document 1).

  In such an ink jet printer, a recording medium is set on a platen by a user before printing. At this time, when the recording medium is not properly set, when the recording medium is sent out, the recording medium is skewed. If printing is performed on a skewed recording medium, the image is distorted and the print quality is degraded. Further, when the skew of the recording medium deteriorates, the recording medium may be wrinkled. Therefore, in order to suppress skewing and wrinkling of the recording medium, in the ink jet printer of Patent Document 1, a tension roller is provided in the recording medium conveyance path, and the recording medium is pressed by the tension roller, thereby the recording medium There has been proposed a configuration in which tension is applied to the.

JP 2011-11889 A

  However, the conventional ink jet printer has a problem that the configuration becomes large by providing a tension roller or the like. Moreover, since tension is applied to the recording medium, the recording medium may be damaged.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an inkjet capable of suppressing or preventing skew of a recording medium with a simple configuration while reducing the possibility of damaging the recording medium. It is to provide a type recording device.

  An ink jet recording apparatus according to the present invention includes a platen that supports a sheet-like recording medium that is conveyed forward during printing, a recording medium conveyance unit that conveys the recording medium forward by driving a roller, and the printing medium before printing. A take-up shaft that is wound around a recording medium and rotatable, a take-up motor that is connected to the take-up shaft and rotates the take-up shaft in a direction in which the record medium is taken up, and the take-up motor And a control device for controlling the rotation operation of the recording medium and the operation of the recording medium conveyance unit, respectively, and the control device controls the recording medium conveyance unit while the winding motor is stopped. After feeding the medium forward by a predetermined amount, skew correction processing is performed to rewind the recording medium backward by controlling the winding motor.

  According to the ink jet recording apparatus of the present invention, the recording medium is fed forward by a predetermined amount by the recording medium transport unit. Then, the recording medium is rewound backward by controlling the winding motor. By executing such skew correction processing, in a state where the recording medium is properly arranged, that is, in the roll-shaped recording medium wound around the take-up shaft, no slack occurs on one end side of the recording medium. It becomes a state. This suppresses or prevents the recording medium from skewing when the recording medium after the skew correction processing is conveyed during printing. Specifically, the reason why the recording medium is skewed is that a slack is produced on one end side of the recording medium in the roll-shaped recording medium wound around the winding shaft. When the recording medium in such a slack state is fed forward by a predetermined amount, when the recording medium is rewound rearward, the other side of the recording medium, that is, the portion of the recording medium on which the slack has not occurred However, a phenomenon occurs in which the film is rewound before the one end side where the slack is generated. This is considered to be because a larger back tension (that is, a tension acting toward the rear) is generated in the portion on the other end side of the recording medium than in the portion on the one end side. As a result, the slack is eliminated, and the recording medium can be corrected to a properly arranged state. As a result, the skew of the recording medium can be suppressed or prevented. Further, since no tension is applied to the recording medium using a member such as a tension roller, the possibility of damaging the recording medium can be reduced. As described above, it is possible to suppress or prevent the skew of the recording medium while reducing the possibility of damaging the recording medium with a simple configuration without using a large component such as a tension roller.

  According to the present invention, it is possible to provide an ink jet recording apparatus that can suppress or prevent skew of a recording medium with a simple configuration while reducing the possibility of damaging the recording medium.

1 is a perspective view of an inkjet printer according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a state in which recording paper is set in the ink jet printer according to the embodiment of the present invention. FIG. 3 is a diagram illustrating a state in which recording paper is fed out in the ink jet printer according to the embodiment of the present invention. FIG. 4 is a diagram illustrating a state where the recording paper is rewound in the ink jet printer according to the embodiment of the present invention. It is a top view of the skew detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the slack of the recording paper used with the inkjet printer which concerns on one Embodiment of this invention. (A) is a top view of the rocking | fluctuation mechanism which concerns on other embodiment of this invention, (b) is a side view of a rocking | fluctuation mechanism.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The ink jet recording apparatus according to the present embodiment is an ink jet printer 100 that performs printing on a recording paper K as a recording medium. In this specification, a direction in which an ink head 107 to be described later moves is appropriately referred to as a “main scanning direction”. The main scanning direction corresponds to the width direction of the recording paper K. A direction perpendicular to the main scanning direction is appropriately referred to as a “sub-scanning direction”. The symbol Y in the drawing represents the main scanning direction. In the present embodiment, the main scanning direction Y is the left-right direction. A symbol X in the drawing indicates a sub-scanning direction. In the present embodiment, the sub-scanning direction X is the front-rear direction. In the following description, left, right, top, and bottom mean left, right, top, and bottom as viewed from an operator in front of the inkjet printer 100, respectively. Further, the direction approaching the worker from the inkjet printer 100 is defined as the front, and the direction away from the worker is defined as the rear. In FIG. 1, symbols F, Re, L, R, U, and D represent front, rear, left, right, upper, and lower, respectively. However, these are only directions for convenience of explanation, and do not limit the installation mode of the inkjet printer 100 according to the present embodiment. The recording medium may be another sheet-like recording medium, such as a resin sheet. The recording medium is not limited to a flexible sheet, and may be a hard recording medium such as a glass substrate.

  As shown in FIG. 1, the ink jet printer 100 according to this embodiment includes a main body 101, side parts 102 and 103, a platen 104, leg parts 105 and 106, and an ink head 107. . The main body 101 is a housing extending in the left-right direction. The platen 104 is provided inside the main body 101 and supports the recording paper K during printing. A side part 102 of the housing is attached to the left part of the main body 101. A side part 103 is attached to the right part of the main body part 101. The platen 104 includes an apron guide 104a that is curved downward and forward. Legs 105 and 106 that support the main body 101 are attached to the lower part of the main body 101. The leg portion 106 is located on the right side of the leg portion 105. The recording paper K is conveyed forward on the platen 104. The ink jet printer 100 may include an irradiation device that irradiates ultraviolet rays in addition to the ink head 107. The ink jet 100 may include a cutting head that cuts the recording medium.

  The ink head 107 is disposed inside the main body 101. The ink head 107 is disposed above the platen 104. Although not shown, the ink head 107 includes a plurality of nozzles opened downward, and ejects ink from these nozzles. The type of ink is not limited at all, and ink that cures when irradiated with ultraviolet rays (so-called UV ink), solvent ink, or the like may be used. The ink head 107 is held by a carriage 108 provided behind the ink head 107. The carriage 108 is engaged with a guide rail 109 extending in the left-right direction. The carriage 108 is configured to move leftward or rightward. As the carriage 108 moves, the ink head 107 also moves to the left or right. The ink head 107 ejects ink while moving left and right.

  The ink jet printer 100 includes a cylindrical grid roller 1 as an example of a transport device that transports the recording paper K. The grid roller 1 extends in the main scanning direction Y. The grid roller 1 is provided on the platen 104. The grid roller 1 is embedded in the platen 104. The upper part of the grid roller 1 is exposed from the platen 104. The grid roller 1 supports the recording paper K from below during printing. The grid roller 1 is driven by a roller driving unit 3 (see FIG. 2). The roller driving unit 3 is, for example, a motor. The grid roller 1 conveys the recording paper K forward. A plurality of pinch rollers 2 are arranged above the grid roller 1. The pinch rollers 2 are juxtaposed in the left-right direction at a predetermined interval. The pinch roller 2 is disposed to face the grid roller 1. The pinch roller 2 is connected to a lift drive unit 4 (see FIG. 2) that lifts and lowers the pinch roller 2. The raising / lowering drive part 4 is a motor, for example. The pinch roller 2 is configured to be movable up and down. When the pinch roller 2 moves downward, the recording paper K is sandwiched between the pinch roller 2 and the grid roller 1. By rotating the grid roller 1 with the recording sheet K sandwiched between the pinch roller 2 and the grid roller 1, the recording sheet K is conveyed forward.

  As shown in FIG. 2, a rotatable take-up shaft 5 for supplying the recording paper K is provided behind the platen 104. The recording paper K before printing is wound around the winding shaft 5 in a roll shape. When the grid roller 1 conveys the recording paper K forward, the recording paper K is sent out from the take-up shaft 5. Here, in the present embodiment, a winding motor 6 is connected to the winding shaft 5. The take-up shaft 5 rotates in the direction in which the recording paper K is rewound by the take-up motor 6. The take-up shaft 5 is perpendicular to the direction in which the recording paper K is rewound. Strictly speaking, the “vertical” of the take-up shaft 5 is not only perpendicular to the rear direction Re, which is the direction in which the recording paper K is rewound, but also the side in the main scanning direction Y and the sub-scanning direction. It is also required to be perpendicular to the vertical direction (that is, the directions of the signs U and D), which is the direction perpendicular to the plane formed by the sides of X. Actually, the inkjet printer 100 is finely adjusted so that the winding shaft 5 is perpendicular to the vertical direction when the machine body is installed. In the present embodiment, it is assumed that adjustment for making the winding shaft 5 perpendicular to the vertical direction is ideally performed. The moving direction of the recording paper rewound by the take-up shaft 5 is the reverse direction, that is, the moving direction of the recording paper K moving forward by the pinch roller 2 and the grid roller 1 described above. The rewinding of the recording paper K by the take-up shaft 5 will be described later.

  As shown in FIG. 2, a skew correction assisting unit 10 that assists the skew correction operation of the recording paper K on the platen 104 when the recording paper K is rewound is provided above the platen 104. In the present embodiment, the ball roller 8 and the elevation drive unit 9 are employed as the skew correction auxiliary unit 10. The ball roller 8 includes a spherical ball portion 8a that contacts the recording paper K from above, and a main body portion 8b that covers the upper portion of the ball portion 8a and rotatably supports the ball portion 8a. The raising / lowering drive part 9 raises / lowers the ball roller 8. The raising / lowering drive part 9 is a motor, for example. Two ball rollers 8 are provided side by side in the front-rear direction and two side by side in the left-right direction. In the present embodiment, a total of four ball rollers 8 are provided. The ball roller 8 is configured to be lowered by the elevating drive unit 9 so that the ball portion 8a contacts the recording paper K from above when the recording paper K to be described later is rewound. The ball roller 8 lowered by the elevating drive unit 9 enables the recording paper K to move in the front-rear and left-right directions while pressing the recording paper K on the platen 104 with a predetermined force. Note that the ball roller 8 and the lifting drive unit 9 may be omitted. In this case, the skew correction of the recording paper K is performed in a state where the pinch roller 2 is lifted above the grid roller 1 by the lift drive unit 4. A paper sensor 11 is provided in front of the ball roller 8 and below the apron guide 104 a of the platen 104. The paper sensor 11 detects the presence or absence of the recording paper K. The paper sensor 11 is an ultrasonic sensor, for example. Note that a sensor other than the ultrasonic sensor may be used as the paper sensor 11.

  The ink jet printer 100 (see FIG. 1) includes a control device 7. The control device 7 is configured by a computer. Although not shown, the control device 7 includes a central processing unit (CPU) and a ROM, a RAM, and the like that store programs executed by the central processing unit. The control device 7 controls the operation of the roller drive unit 3, the operation of the take-up motor 6, and the operations of the elevating drive units 4 and 9.

  Next, skew correction processing for correcting the skew of the recording paper K will be described. Prior to starting printing in the inkjet printer 100, the recording paper K is placed on the platen 104 by the operator. At this time, the pinch roller 2 and the ball roller 8 are arranged above the platen 104 so as not to contact the recording paper K, respectively. The platen 104 is provided with a mark (not shown) for positioning the recording paper K. The mark is provided at the right end of the upper surface of the platen 104, for example. The operator sets the recording sheet K so that the right end of the front end Kf of the recording sheet K matches the mark. Note that the position of the mark for positioning the recording paper K when the recording paper K is set is not particularly limited, and may be provided at the left end of the upper surface of the platen 104. As shown in FIG. 2, the operator sets the recording paper K so that the front end Kf of the recording paper K is disposed at a position on the apron guide 104 a of the platen 104 and at a position P1 behind the paper sensor 11. . Here, when the recording paper K is set in accordance with the mark as described above, a slack T may occur at the right end of the recording paper K wound around the winding shaft 5 as shown in FIG. . The slack T at the right end refers to a portion that floats from the outermost surface without contacting the outermost surface of the recording paper K that is wound around the winding shaft 5. When the recording paper K having such a slack T is conveyed, the recording paper K is skewed. That is, such slack T causes the recording paper K to skew. Therefore, in the present embodiment, the following skew correction processing is performed.

  From the state of FIG. 2, first, as shown in FIG. 3, the pinch roller 2 is lowered to a position where the pinch roller 2 comes into contact with the recording paper K by the lift drive unit 4. Then, the grid roller 1 is rotated by the roller driving unit 3 while the winding motor 6 is stopped, and the recording paper K is fed forward by a predetermined amount as shown in FIG. In this case, the recording paper K is sent to a position P2 where the front end Kf of the recording paper K is ahead of the paper sensor 11. The ball roller 8 is on standby so as not to contact the recording paper K.

  Next, as shown in FIG. 4, the pinch roller 2 is moved upward by the lift drive unit 4 and retracted, and the ball roller 8 is lowered to a position where it contacts the recording paper K by the lift drive unit 9. In this state, the take-up motor 5 rotates the take-up shaft 5 (counterclockwise in FIG. 4) to rewind the recording paper K backward. In this case, the recording paper K is rewound to a position P3 where the front edge Kf of the recording paper K is detected by the paper sensor 11. At this time, the recording paper K is rewound while the upper surface of the recording paper K is in contact with the ball portion 8 a of the ball roller 8. When the recording paper K is rewound backward in this way, as shown in FIG. 6, the portion on the left end Kl side of the recording paper K is rewound before the portion on the right end Kr side where the slackness T occurs. Phenomenon occurs. This is because it is considered that a larger back tension (that is, a tension acting toward the rear) is generated in the portion on the left end Kl side of the recording paper K than in the portion on the right end Kr side. When the back tension generated at the left end Kl side portion of the recording paper K is applied to the recording paper K, the recording paper K gradually moves to the left while moving in the winding direction when it is wound around the winding shaft 5. Start moving. As a result, the slackness T is eliminated, and the recording paper K can be corrected to a properly arranged state. Note that when the recording paper K is rewound, the recording paper K only needs to be detected by the paper sensor 11, and the paper sensor 11 detects the portion of the recording paper K behind the front end Kf of the recording paper K. You may rewind to.

  Here, when the recording paper K is fed forward as shown in FIG. 3 described above, it is detected whether or not the recording paper K is skewed. As shown in FIG. 5, the carriage 108 is provided with a skew detection device 12 that detects the skew of the recording paper K. The skew detection device 12 is, for example, an optical sensor. However, the skew detection device 12 is not particularly limited to an optical sensor, and other sensors may be used. When skew detection is performed, first, the position of the right end Kfr of the front end Kf of the recording paper K is detected by the skew detection device 12. Next, after feeding the recording sheet K by a certain amount G1, the skew detection device 12 detects the position of the right end Kr of the recording sheet K. The skew amount G2 per unit feed amount is detected based on the difference between the two detection results. Note that the left end of the recording sheet K may be detected when the skew feeding is detected. When the skew amount G2 detected by the skew detection device 12 is not 0, that is, when the slack T (see FIG. 6) is generated, the skew correction process described above may be executed.

  As described above, according to the present embodiment, the recording paper K is fed forward by a predetermined amount by the grid roller 1. Thereafter, the recording paper K is rewound backward by controlling the winding motor 6. By executing such skew correction processing, the recording paper K is properly arranged, that is, in the roll-shaped recording paper K wound around the take-up shaft 5, the recording paper K is slackened to one end side. T is not generated. This suppresses or prevents the recording paper K from skewing when the recording paper K after the skew correction processing is conveyed during printing. Specifically, the recording paper K is skewed because a slack T occurs on one end side of the recording paper K in the roll-shaped recording paper K wound around the take-up shaft 5. After the recording paper K in a state where the slack T is generated in this way is fed forward by a predetermined amount, when the recording paper K is rewound backward, the other end side of the recording paper K, that is, the side where the slack T is not generated. This causes a phenomenon that the portion of the recording paper K is rewound before the portion on one end where the slackness T occurs. This is presumably because a larger back tension (that is, a tension acting toward the rear) is generated in the portion on the other end side of the recording paper K than in the portion on the one end side. As a result, the slackness T is eliminated, and the recording paper K can be corrected to a properly arranged state. As a result, it is possible to suppress or prevent the skew of the recording sheet K after the skew correction process. Further, since no tension is applied to the recording paper K using a member such as a tension roller, the possibility of damaging the recording paper K can be reduced. As described above, it is possible to suppress or prevent the skew of the recording sheet K while reducing the possibility of damaging the recording sheet K with a simple configuration without using a large component such as a tension roller.

  Further, according to the present embodiment, the skew correction process is executed when the skew detection amount of the recording paper K is detected by the skew detection device 12. As a result, when the recording paper K is not skewed, it is not necessary to execute the skew correction process, and therefore the recording paper K can be transported quickly.

  Further, according to the present embodiment, when the recording paper K is rewound, the pressing of the recording paper K by the pinch roller 2 is released, and the frictional force of the platen 104 against the recording paper K is caused by the skew correction auxiliary unit 10. Reduced. Thereby, it is possible to reduce the load on the recording paper K when the recording paper K is rewound. Thereby, it is possible to avoid the recording paper K from being wrinkled or damaged during rewinding.

  Further, according to the present embodiment, when the recording paper K is rewound, the pressing of the recording paper K by the pinch roller 2 is released, and the recording paper K is skewed while moving in the winding direction. Start moving gradually in the direction that the condition disappears. Thereby, it is possible to avoid the recording paper K from being wrinkled or damaged during rewinding.

  Further, according to the present embodiment, during the skew correction process, the recording paper K is sent from the position P1 behind the paper sensor 11 to the position P2 ahead of the paper sensor 11. For this reason, the paper sensor 11 can detect whether or not the recording paper K has been reliably fed forward.

  Further, according to the present embodiment, during the skew correction process, the recording paper K sent to the position P2 ahead of the paper sensor 11 is rewound to at least the position P3 detected by the paper sensor 11. ing. Accordingly, when printing is started after the skew correction is completed, it is not necessary to send out the recording paper K again to the position detected by the paper sensor 11, and the recording paper K can be conveyed quickly.

  The embodiment of the present invention has been described above. However, the above-described embodiments are merely examples, and the present invention can be implemented in various other forms as follows.

  A rocking mechanism 16 for rocking the recording paper K as described below may be added to the configuration of the above embodiment. As shown in FIGS. 7A and 7B, the swing mechanism 16 extends in the main scanning direction Y, and freely rotates to swing the recording paper K up and down by contacting the recording paper K from below. The cam 13, a rotating shaft 14 provided on the cam 13, and a swinging motor 15 connected to the rotating shaft 14 are provided. The platen 104 is provided with a rectangular hole 104b extending in the main scanning direction Y. The cam 13 is provided so that at least a part of the cam 13 protrudes upward from the hole 104 b of the platen 104 depending on the rotation angle. In such a configuration, the control device 7 (see FIG. 2) rotates the cam 13 by driving the swing motor 15 when the recording paper K is rewound. By rotating the cam 13 when the recording paper K is rewound, the recording paper K is swung up and down. As a result, the slack T of the recording paper K is easily eliminated, and it is easy to correct the recording paper K to a properly disposed state. That is, skew correction can be promoted.

  Moreover, in the said embodiment, although the ball roller 8 and the raising / lowering drive part 9 were used as the skew correction auxiliary | assistant part 10, it is not limited to this. For example, an air supply mechanism may be employed as the skew correction auxiliary unit 10. In this case, when the recording paper K is rewound, air is supplied from above to the recording paper K by the air supply mechanism to assist the rewinding of the recording paper K.

  In the above-described embodiment, the skew correction process is executed when the skew amount G2 detected by the skew detection device 12 is not 0, in other words, when the slack T occurs in the recording paper K. However, the present invention is not limited to this. The skew correction process may be executed even when the skew amount G2 detected by the skew detection device 12 is zero. Thereby, the reliability can be further improved.

  In the above embodiment, the recording paper K is rewound to the position P3 where the front edge Kf of the recording paper K is detected by the paper sensor 11. However, the present invention is not limited to this. You may make it rewind to the position which is not detected by the paper sensor 11. FIG.

  Moreover, in the said embodiment, although the cam 13 was used as the rocking | fluctuation mechanism 16, it is not limited to this. You may comprise so that the air for rocking the recording paper K may be supplied with respect to the recording paper K from the lower part of the platen 104 through the hole 104b.

DESCRIPTION OF SYMBOLS 1 Grid roller 2 Pinch roller 3 Roller drive part 4 Lift drive part (1st lift drive part)
DESCRIPTION OF SYMBOLS 5 Winding shaft 6 Winding motor 7 Control apparatus 8 Ball roller 8a Ball part 8b Main body part 9 Lifting drive part (2nd lifting drive part)
10 Skew correction auxiliary section 11 Paper sensor (sensor)
12 Skew detection device 13 Cam 14 Rotating shaft 15 Oscillating motor 16 Oscillating mechanism 100 Inkjet printer 104 Platen 104a Apron guide 104b Hole 107 Ink head 108 Carriage K Recording paper X Sub-scanning direction Y Main scanning direction

Claims (9)

A platen that supports a sheet-like recording medium conveyed forward during printing;
A recording medium transport unit that transports the recording medium forward by driving a roller;
The recording medium before printing is wound, and a rotatable winding shaft;
A winding motor connected to the winding shaft and rotating the winding shaft in a direction in which the recording medium is wound;
A control device for controlling the rotation operation of the winding motor and the operation of the recording medium transport unit, respectively,
The control device controls the recording medium conveying unit while the winding motor is stopped to feed the recording medium forward by a predetermined amount, and then controls the winding motor to control the recording medium. An ink jet recording apparatus configured to execute a skew correction process for rewinding a medium backward. An ink head for ejecting ink onto the recording medium on the platen;
A carriage for holding the ink head;
A skew detection device that is provided in the carriage and detects a skew amount per unit feed amount of the recording medium,
2. The ink jet recording apparatus according to claim 1, wherein the control device is configured to execute the skew correction processing when the skew amount detected by the skew detection device is not zero.   The recording medium transport unit includes a grid roller that is provided on the platen and supports the recording medium from below, and a pinch roller that faces the grid roller through the recording medium and is pressed against the recording medium. The ink jet recording apparatus according to claim 1, comprising the ink jet recording apparatus. The pinch roller is configured to be movable up and down,
A first raising / lowering driving part for raising and lowering the pinch roller;
A skew correction assisting unit for assisting a skew correction operation of the recording medium when the recording medium is rewound,
The control device is configured to release the pressing of the pinch roller against the recording medium by raising the pinch roller by the first elevating drive unit when the recording medium is rewound. 4. An ink jet recording apparatus according to item 3. The skew feeding correction assisting portion includes a ball roller having a ball portion that comes into contact with the recording medium from above and a main body portion that rotatably supports the ball portion, a second lifting drive portion that lifts and lowers the ball roller, Including
5. The control device is configured to lower the ball roller by the second elevating drive unit so that the ball unit comes into contact with the recording medium from above when the recording medium is rewound. 2. An ink jet recording apparatus according to 1. The platen includes an apron guide that is curved downward and forward.
A sensor provided in front of the ball roller and below the apron guide for detecting the presence or absence of the recording medium;
The ink jet recording apparatus according to claim 5, wherein the control device is configured to send the recording medium from a position behind the sensor to a position ahead of the sensor.   The ink jet recording apparatus according to claim 6, wherein the control device is configured to rewind the recording medium from a position ahead of the sensor to at least a position detected by the sensor. A rotatable cam that extends in the main scanning direction and swings the recording medium in the vertical direction by contacting the recording medium from below, a rotating shaft provided on the cam, and a swing connected to the rotating shaft. A swing mechanism having a motor for driving,
The ink jet recording according to any one of claims 1 to 7, wherein the control device is configured to rotate the cam by driving the swing motor when the recording medium is rewound. apparatus. The platen is provided with a rectangular hole extending in the main scanning direction,
The ink jet recording apparatus according to claim 8, wherein the cam of the swing mechanism is provided so that at least a part of the cam protrudes upward from the hole depending on a rotation angle.

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