JP4389752B2 - Image recording device - Google Patents

Description

  The present invention relates to an image recording apparatus, and more particularly to an image recording apparatus that records an image on a recording medium conveyed by an endless belt.

An image recording apparatus that ejects ink onto a recording medium such as paper, film, and cloth and records an image on the recording medium includes, for example, an endless belt for supporting and conveying the recording medium, and an endless belt There is a system in which a recording medium is conveyed by at least two rollers that stretch the belt. When one of the two rollers is rotationally driven, the endless belt and the other roller are rotated following the rotation, whereby the recording medium on the endless belt is conveyed. Here, as the conveyance of the recording medium proceeds, the endless belt is displaced in a direction orthogonal to the conveyance direction, and thus the deviation needs to be corrected. For example, Patent Document 1 describes a method of correcting a deviation of an endless belt by tilting a driving roller of two rollers. Further, in Patent Document 2, the electrostatic adsorption force is applied to the endless belt by a charging roller to electrostatically attract the recording medium onto the belt, and the electrostatic adsorption is stabilized by removing dirt on the belt. A system for preventing the recording medium from floating on the belt and reducing the deviation is described.
Japanese Patent Laid-Open No. 5-24704 JP 2004-217373 A

Here, according to the experiments of the present inventors, endless belt misalignment correction is not always performed stably, and in some cases, wrinkles may occur in the belt due to increased friction between the endless belt and the roller. confirmed. If wrinkles occur, the wrinkles also form irregularities on the recording medium on the endless belt, changing the relative distance from the recording head, the angle, and the like, resulting in an adverse effect on image quality. In particular, when the recording medium is attracted to the endless belt by electrostatic attraction as in Patent Document 2, wrinkles are likely to occur due to the friction between the charging roller and the endless belt and the electrostatic attraction action. There is a risk of adversely affecting the effects.
Furthermore, if the wavy surface of the endless belt is large, the endless belt may come into contact with the recording head and cause a failure of the recording head.

  SUMMARY OF THE INVENTION An object of the present invention is to reduce the amount of wrinkles and the amount of waviness that occur at the time of correcting a deviation of an endless belt, thereby stabilizing the image quality and preventing a print head failure.

An image recording apparatus according to the invention of claim 1
An endless belt that conveys while supporting the recording medium;
A recording head for recording an image by discharging ink to a recording medium supported by the endless belt;
A plurality of rollers that convey the recording medium on the endless belt by stretching and rotating the endless belt;
By moving one end portion of at least one roller relative to one end portion of the other rollers among the plurality of rollers, the tension on the endless belt is changed, and the endless belt is moved in the rotational direction. A belt moving unit that moves in a direction orthogonal to the
A deviation detection sensor for detecting a deviation direction of the endless belt;
An electrostatic force generator for generating an electrostatic adsorption force with respect to the recording medium on the endless belt;
A control unit that controls the recording head and the belt moving unit based on a detection result of the deviation detection sensor;
The recording head is a serial type recording head that ejects ink while scanning in a direction orthogonal to the conveyance direction of the recording medium,
The controller is configured to move the endless belt based on the detection result of the deviation detection sensor while the recording head is positioned outside the recording area and while the recording medium is being conveyed. The belt moving unit is controlled so as to complete the correction operation.

  According to the first aspect of the present invention, since the shift correction operation is completed while the recording medium is being conveyed, one end of at least one of the plurality of rollers is connected to one end of the other roller. When moving relative to the endless belt, the endless belt always rotates. That is, the endless belt moves in a direction orthogonal to the rotation direction while rotating. As a result, the load generated between the endless belt and the roller is reduced, so that the endless belt misalignment correction is performed smoothly. As a result, the amount of wrinkles and undulations generated during the endless belt misalignment correction is reduced. It becomes possible to reduce. If the amount of wrinkles and the amount of waviness can be reduced in this way, the image quality can be stabilized, and further, the failure of the recording head can be prevented.

Here, as described above, even if the amount of wrinkles and undulations generated in the endless belt is reduced, the generation amount and undulations are not zero. There is a risk of wrinkles. If an image is recorded with a wrinkle on the recording medium, the image quality becomes unstable. However, as in the first aspect of the invention, if the misalignment correction operation is completed while the recording head is located outside the recording area, an image is recorded on the recording medium during the misalignment correction operation. Therefore, the image quality can be stabilized. In particular, since no vibration due to the deviation correction operation occurs during image recording, the vibration does not adversely affect the image quality, and as a result, the image quality can be further stabilized.

When an electrostatic force is applied to the recording medium by the electrostatic force generation unit and the endless belt, and the recording medium is attracted to the endless belt, wrinkles are likely to occur because the frictional force increases although the conveyance performance is improved. However, even if the electrostatic attraction force is applied to the recording medium as in the first aspect of the invention, the amount of wrinkles and the amount of waviness are reduced, so that the adverse effect on the image quality can be suppressed. Can be stabilized.

  According to the present invention, since the load generated between the endless belt and the roller is reduced, the endless belt misalignment correction is performed smoothly. As a result, the amount of wrinkles generated during the endless belt misalignment correction is reduced. The amount of undulation can be reduced. If the amount of wrinkles and the amount of waviness can be reduced in this way, the image quality can be stabilized, and further, the failure of the recording head can be prevented.

  FIG. 1 is a side view showing a main configuration of an image recording apparatus according to the present embodiment, and FIG. 2 is a top view. As shown in FIGS. 1 and 2, the image recording apparatus 1 has an endless belt 2 that supports the recording medium P on its surface in a direction perpendicular to the conveyance direction C of the recording medium P (left and right direction in FIG. 2). It is arranged to extend along. Below the portion of the endless belt 2 that supports the recording medium P, there is provided an electrostatic force generator 40 that generates an electrostatic adsorption force with respect to the recording medium P on the endless belt 2. The electrostatic force generator 40 has a plurality of counter electrodes (not shown) in which negative electrodes and positive electrodes are alternately arranged in a comb-teeth shape, and by applying a DC voltage to the counter electrodes, The electrostatic force generator 40 and the endless belt 2 apply an electrostatic attraction force to the recording medium P. Above the endless belt 2, a recording head 30 that ejects ink and records an image on the recording medium P supported by the endless belt 2 is disposed. The recording head 30 is mounted on a carriage (not shown) that scans in a direction orthogonal to the conveyance direction C. That is, the recording head 30 is a serial recording head that ejects ink while scanning in a direction orthogonal to the conveyance direction C.

  In addition, the image recording apparatus 1 includes a drive roller 3 that is driven to rotate, a rotatable driven roller 4, and a tension roller that applies a predetermined tension to the endless belt 2. 31 is provided. The drive roller 3 is disposed so as to extend along a direction (left-right direction in FIG. 2) orthogonal to the rotation direction of the endless belt 2. Further, the driven roller 4 is disposed so as to be substantially parallel to the driving roller 3 on the upstream side in the conveying direction C of the driving roller 3. The tension roller 31 is disposed so as to be substantially parallel to the drive roller 3 below and approximately in the middle between the drive roller 3 and the driven roller 4. Both ends of the driving roller 3, the driven roller 4, and the tension roller 31 are supported by bearings (not shown), but the bearings supporting the both ends of the driving roller 3 and the right end of the driven roller 4 do not move. The bearing that supports the left end of the driven roller 4 is moved along the conveyance direction C, although it is fixed at a predetermined position. Hereinafter, the bearing that supports the left end portion of the driven roller 4 is referred to as a moving bearing.

  A deviation detection sensor 6 for detecting whether or not the left end portion 21 of the endless belt 2 is at the reference position is provided below the left end portion 21 of the endless belt 2 in order to detect the deviation direction of the endless belt 2. It has been. A pair of limit sensors 5 and 7 for detecting whether or not the endless belt 2 is in a range where it can be normally operated are provided on both sides of the deviation detection sensor 6. The deviation detection sensor 6 and the limit sensors 5 and 7 are optical binary sensors. The binary sensor outputs two types of signals, and outputs different signals when the endless belt 2 is present at the opposite position and when the endless belt 2 is not present. Here, both end portions of the endless belt 2 are slightly wavy and formed in a non-linear shape even when cut in a straight line. For this reason, when the endless belt 2 rotates with the end portion facing the binary sensor, the binary sensor detects the waviness of the end portion and repeatedly outputs different signals.

  FIG. 3 is a block diagram illustrating a main control unit of the image recording apparatus 1. As shown in FIG. 3, the image recording apparatus 1 is provided with a control unit 10 that controls each drive unit. The control unit 10 includes a conveying motor 11 that rotationally drives the driving roller 3, a scanning motor 32 that scans the carriage, a bearing motor 12 that moves the moving bearing, and various instructions such as an image recording start instruction. Are input, the monitor 14 for notifying the operator of various information, the storage unit 15, the displacement detection sensor 6, the limit sensors 5, 7, and the recording head 30 are electrically connected. ing. In addition to the above, each drive unit of the image recording apparatus 1 is connected to the control unit 10.

  Here, when the bearing motor 12 moves the moving bearing, the tension with respect to the endless belt 2 is changed, and as a result, the endless belt 2 moves in the left-right direction. That is, the bearing motor 12 and the moving bearing are the belt moving unit according to the present invention.

Examples of the control data stored in the storage unit 15 include the movement range of the moving bearing and the basic movement amount.
The moving range is a range in which the driven roller 4 can be tilted with reference to a position where the driven roller 4 is parallel to the driving roller 3 as shown in FIG. For example, if the upstream side in the transport direction C is “−” and the downstream side is “+”, the driven roller 4 can be tilted in the range of −B to + B. The moving range of the moving bearing is determined based on the + B range.

  The basic movement amount of the moving bearing is a value obtained by multiplying the minimum movement amount by which the endless belt 2 can be moved in the left-right direction when the driven roller 4 is tilted by a predetermined value. For example, if the driving roller 3 and the driven roller 4 are parallel, the tension acting on the endless belt 2 is substantially uniform in the left-right direction. Therefore, if no external load is applied, the endless belt 2 moves in the left-right direction. It is hard to slip. However, when the moving bearing is moved by the minimum amount of movement and the driven roller 4 is tilted, the tension acting on the endless belt 2 becomes non-uniform in the left-right direction, and the endless belt 2 moves in the left-right direction. It becomes like this. For example, when the minimum movement amount is A, when the movement bearing is moved by -A, the driven roller 4 is inclined as indicated by the one-dot chain line portion D in FIG. Thereby, since the tension with respect to the right end part of the endless belt 2 becomes smaller than the tension with respect to the left end part, the endless belt 2 moves toward the right (arrow E). On the other hand, when the moving bearing is moved by + A, the driven roller 4 tilts as indicated by the alternate long and short dash line F. Thereby, the tension with respect to the right end of the endless belt 2 becomes larger than the tension with respect to the left end, so that the endless belt 2 moves toward the left (arrow G). It should be noted that the minimum moving amount magnification can be set within a range where the basic moving amount does not exceed the moving range.

  The control unit 10 controls various devices according to a control program and control data written in the storage unit 15. For example, the control unit 10 performs a deviation correction operation for moving the endless belt 2 based on the detection result of the deviation detection sensor 6. Specifically, the control unit 10 controls the belt moving unit based on the basic moving amount, the minimum moving amount, the magnification and the moving range in order to complete the above-described misalignment correction operation while the recording medium P is being conveyed. It is supposed to be. As the deviation correction operation, for example, the endless belt 2 is moved in the direction opposite to the direction of deviation of the endless belt 2 detected by the deviation detection sensor 6, or the endless belt 2 is switched by switching to the same direction as the direction of deviation. The endless belt 2 may be moved or moved in the same direction as the displacement direction. In the present embodiment, however, the endless belt 2 is detected in a direction opposite to the displacement direction detected by the displacement detection sensor 6. The case where the endless belt 2 is moved is illustrated.

  Next, the operation of the image recording apparatus 1 of the present embodiment will be described.

  When an image recording start instruction is input to the input unit 13 by the operator, the control unit 10 controls the transport motor 11 to transport the recording medium P intermittently. During the intermittent conveyance, the control unit 10 controls the scanning motor 32 and the recording head 30 to eject ink from the recording head 30 to the recording medium P while scanning the carriage in accordance with the timing at which the recording medium P stops. I am letting. By repeating this operation, an image is recorded on the recording medium P.

  Here, during the conveyance of the recording medium P during the intermittent conveyance, the control unit 10 controls the belt moving unit while controlling the scanning motor 32 to retract the carriage and the recording head 30 out of the recording area. The deviation of the endless belt 2 is corrected by executing the deviation correction operation. FIG. 4 is a flowchart of the deviation correction operation. When the misalignment correction operation is started as shown in FIG. 4, the control unit 10 detects the misalignment direction of the endless belt 2 by the misalignment detection sensor 6 (step S1). As described above, both end portions of the endless belt 2 are slightly waved and formed in a non-linear shape. Therefore, if there is no deviation, the deviation detection sensor 6 outputs an ON / OFF signal while switching, FIG. If it is shifted to the left, an ON signal is output, and if it is shifted to the right, an OFF signal is output. That is, the control unit 10 recognizes the deviation direction of the endless belt 2 based on the output signal of the deviation detection sensor 6.

  In step S <b> 2, the control unit 10 determines whether or not the endless belt deviation correction is completed within the conveyance time, assuming that the driven roller 4 is inclined based on the basic movement amount. The conveyance time is a time required for one conveyance when the recording medium P is intermittently conveyed while repeating conveyance and stoppage, and is calculated by the control unit 10 based on the image data of the recorded image collection. The control unit 10 determines whether the deviation correction of the endless belt 2 is completed within the conveyance time from the conveyance time and the preset basic movement amount, assuming that the driven roller 4 is tilted by the basic movement amount. If it is determined that it is possible, the process proceeds to step S4. If it is determined that it is not possible, the process proceeds to step S3.

  In step S3, the control unit 10 reduces the magnification with respect to the minimum movement amount, and resets the basic movement amount so that the deviation correction of the endless belt 2 is completed within the conveyance time. In addition, when the deviation correction of the endless belt 2 is not completely completed by one conveyance, the deviation correction may be completed by a plurality of conveyances.

  In step S4, the control unit 10 controls the bearing motor 12 and the conveyance motor 11 to rotate the driving roller 3 while tilting the driven roller 4, thereby correcting the deviation while rotating the endless belt 2 and recording medium. P is transported. That is, the deviation correction operation of the endless belt 2 is completed while the image is not recorded and the recording medium P is being conveyed, as shown in FIG.

  As described above, according to the image recording apparatus 1 of the present embodiment, the displacement correction operation is completed while the recording medium P is being conveyed. Therefore, among the driving roller 3, the driven roller 4, and the tension roller 31, When one end of the driven roller 4 moves relative to one end of the driving roller 3, the endless belt 2 is always in a rotating state. That is, the endless belt 2 moves in a direction orthogonal to the rotation direction while rotating. Thereby, since the load generated between the endless belt 2 and each roller is reduced, the deviation correction of the endless belt 2 is performed smoothly. As a result, the amount of wrinkles generated at the time of deviation correction of the endless belt 2 is generated. And the amount of undulation can be reduced. If the amount of wrinkles generated and the amount of waviness can be reduced in this way, the image quality can be stabilized, and further, the failure of the recording head can be prevented.

  Here, even if the amount of wrinkles and the amount of waviness generated in the endless belt 2 are reduced, the amount of wrinkles and the amount of waviness is not zero. May also occur. If an image is recorded in a state where the recording medium P is wrinkled, the image quality becomes unstable. However, as described above, if the displacement correction operation is completed while the recording head 30 is located outside the recording area, an image is not recorded on the recording medium P during the displacement correction operation. In addition, the image quality can be stabilized.

  When electrostatic force is applied to the endless belt 2 by the electrostatic force generator 40 and the recording medium is attracted onto the endless belt 2, wrinkles are likely to occur due to the electrostatic attraction action of the endless belt 2. With such a configuration, even if an electrostatic attraction force is applied to the endless belt 2, the amount of wrinkles and the amount of waviness is reduced, so that adverse effects on image quality can be suppressed, and image quality can be stabilized. Can be realized.

It is needless to say that the present invention is not limited to the above embodiment and can be modified as appropriate.
For example, in the present embodiment, the case where the endless belt 2 is stretched and the roller to be rotated is composed of the driving roller 3, the driven roller 4, and the tension roller 31 is illustrated, but there are two or four or more rollers. May be. Even in these cases, if the belt moving unit moves one end of at least one of the plurality of rollers relative to one end of the other roller, the tension on the endless belt 2 can be changed. The endless belt 2 can be moved in the left-right direction.

1 is a side view illustrating a schematic configuration of an image recording apparatus according to an embodiment. FIG. 2 is a top view illustrating a schematic configuration of the image recording apparatus in FIG. 1. FIG. 2 is a block diagram illustrating a main control configuration of the image recording apparatus in FIG. 1. 3 is a flowchart showing a deviation correction operation performed in the image recording apparatus of FIG. 1. FIG. 5 is a timing chart showing timing at which the misalignment correction operation of FIG. 4 is performed.

Explanation of symbols

1 Image Recording Device 3 Drive Roller
4 Followed roller (roller)
6 Deviation detection sensor 10 Control unit 12 Motor for bearing (belt moving unit)
DESCRIPTION OF SYMBOLS 15 Memory | storage part 30 Recording head 40 Electrostatic force generation part 31 Tension roller (roller)
P Recording medium

Claims (1)

An endless belt that conveys while supporting the recording medium;
A recording head for recording an image by discharging ink to a recording medium supported by the endless belt;
A plurality of rollers that convey the recording medium on the endless belt by stretching and rotating the endless belt;
By moving one end of at least one roller relative to one end of the other roller among the plurality of rollers, the tension on the endless belt is changed, and the endless belt is moved in the rotational direction. A belt moving unit that moves in a direction orthogonal to the
A deviation detection sensor for detecting a deviation direction of the endless belt;
An electrostatic force generator for generating an electrostatic adsorption force with respect to the recording medium on the endless belt;
A control unit for controlling the recording head and the belt moving unit based on a detection result of the deviation detection sensor,
The recording head is a serial type recording head that ejects ink while scanning in a direction orthogonal to the conveyance direction of the recording medium,
The controller is configured to move the endless belt based on a detection result of the deviation detection sensor while the recording head is positioned outside the recording area and while the recording medium is being conveyed. An image recording apparatus, wherein the belt moving unit is controlled to complete a correction operation.

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