JP2017132151A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer which detects that an interval between a recording head and a recording medium becomes a prescribed value or less, controls the movement of a carriage, prevents contact between the recording medium and the recording head and continues recording.SOLUTION: A detection sensor 9 for detecting a recording medium is mounted on a carriage 1 mounted with a recording head. The detection sensor 9 is arranged at a prescribed distance from a platen 6 and detects the recording medium. When the recording medium is detected, the carriage 1 is raised, and recording is continued while preventing contact between the recording head and the recording medium. Discharge control of the recording head is changed in accordance with the raising of the carriage 1 and deterioration in the recording quality is prevented to continue recording.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an inkjet printer.

  2. Related Art Inkjet printers that record images by ejecting ink from an inkjet recording head onto a recording medium such as paper or a resin film are known. In an ink jet printer, a recording head is mounted on a carriage at a distance of several millimeters with respect to a recording medium, and the carriage is reciprocated in a direction intersecting the recording medium conveyance direction, for example, in a direction perpendicular to the recording medium. Ink is discharged while recording. The recording medium is conveyed by a conveying means. Conveyance is performed between the forward path and the backward path of reciprocating scanning, and a desired image is completed by alternately performing recording and conveyance.

  When there is abnormal conveyance such as when the recording medium is bent and conveyed, the recording head and the recording medium come into contact with each other. The contact between the recording medium and the recording head causes a problem that the carriage cannot run. Further, rubbing between the recording head and the recording medium and damage to the nozzles may cause problems such as ink non-ejection and ink flying bending. When the recording head fails, it is necessary to replace the recording head.

  For example, in Japanese Patent Laid-Open No. 2015-93437, when a paper jam is detected, conveyance of the recording paper is stopped, the recording head is moved away from the recording paper, and then recorded at a position where there is no recording paper. A technique for moving the head, releasing the nip of the recording paper, and removing the jammed recording paper is disclosed.

JP2015-93437A

  However, in the conventional technique, after the paper jam occurs, the recording paper is removed, so that it is necessary to print again to obtain a completed image. Therefore, there is a problem that a lot of waste occurs in the paper and ink. Moreover, it took time and wasted time. In particular, when image recording is nearing the end, or when a long image is recorded using a roll-shaped recording medium, waste is increased. That is, when there is a paper jam, the carriage is raised, moved to the retracted position, and then the paper is reworked, so that there is a problem that continuous printing cannot be performed.

  Provided is an ink jet printer that detects a paper jam sign before a paper jam occurs and, when the sign is detected, takes a jam avoidance measure to prevent paper jam and continue recording.

  An ink jet printer according to the present invention includes a recording head in which a plurality of nozzles are arranged and ejects ink from the nozzles toward a recording medium, a platen that supports the recording medium, a conveying unit that conveys the recording medium, A carriage mounted with a recording head and reciprocating in a scanning direction intersecting with the conveyance direction of the recording medium; a recording medium detection sensor for detecting lifting of the recording medium conveyed on the platen from the platen; Elevating means for moving the carriage in the direction of contact with and separating from the platen along the ink ejection direction of the recording head, and based on the detection result of the recording medium detection sensor, the carriage and the Control means for controlling the operation of the recording head, and an image on the recording medium supported by the platen. In the ink jet printer for recording, when the recording medium detection sensor detects the lifting of the recording medium from the platen, the control means controls the elevating means to move the carriage away from the platen by a predetermined amount. In addition, control is performed to change the ejection timing of the ink from the recording head in accordance with the amount of movement.

  According to the present invention, it is possible to continue recording while avoiding jamming. Further, it is possible to prevent waste of recording media and ink due to jamming. Even if there is some floating on the recording medium on the platen, recording can be continued and the risk of jamming can be reduced. Further, even when the recording medium is lifted up while being recorded halfway, it is possible to record with suitable image quality to the end without giving up recording.

FIG. 1 is a view from the side of the carriage. FIG. 2 is a block diagram of the ink jet printer. FIG. 3 is a diagram for explaining the lifting and lowering operation of the carriage. FIG. 4 is a diagram for explaining the ink ejection operation. FIG. 5 is an external view of the ink jet printer.

  Embodiments of the present invention will be described with reference to the drawings.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a view from the side of the carriage. The carriage 1 will be described with reference to this figure. A rail arranged along the platen 6 is movably fixed. In this figure, the rail is not shown, but the carriage 1 moves in the depth direction of the paper. The rails are arranged along the longitudinal direction of the ink jet printer, and the carriage 1 can move along the rails. The detection plate 3 is fixed to the side surface of the carriage 1. Although only one side will be described here, it is provided on both sides. When the detection plate 3 comes into contact with the recording medium, bending or distortion occurs, and this deformation is detected by the detection sensor 9 fixed to the detection plate 3. For example, these sensors include a piezoelectric element, generate electricity by being deformed, and output a signal. There is a paper guide 7 on the downstream side in the transport direction of the recording medium transported on the platen 6.

  The carriage 1 is provided with an elevating mechanism 2 that moves a surface of the carriage 1 facing the platen 6 in a direction in which the carriage 1 comes in contact with and separates from the platen 6. That is, the carriage 1 can be moved up and down along the ink ejection direction from the recording head. Thus, when the nozzle surface of the recording head fixed to the carriage 1 is at a position facing the platen 6, the interval between the nozzle surface and the platen 6 can be varied. Here, the direction approaching the platen 6 will be described as a downward direction, and the direction away from the platen 6 will be described as an upward direction.

  The lifting mechanism 2 can change the vertical distance between the carriage 1 and the platen 6 or the recording medium supported on the platen 6. A distance sensor 12 is provided for measuring the distance to the surface 10 of the platen 6. For example, the movement distance when the distance sensor 12 is moved up and down is measured using the position of the nozzle surface as a reference position, and the distance from the nozzle surface to the platen 6 or the recording medium can be obtained.

  Further, for example, the position of the edge 13 on the side facing the platen 6 of the detection plate 3 is set as the first reference position. The detection plate 3 is provided for detecting lifting of the recording medium such as irregularities caused by wrinkles or twists of the recording medium. First, the vertical distance from the edge 13 to the platen 6 or the recording medium without distortion is measured first. Further, the thickness of the recording medium can be acquired from the difference between the distance from the first reference position to the platen 6 and the distance from the first reference position to the recording medium.

  By scanning the carriage 1, the lifted state of the recording medium can be confirmed. When the detection plate 3 comes into contact with the recording medium, a signal is output from the detection sensor 9 fixed to the detection plate 3. This signal indicates that there is a protruding portion on the recording medium, that is, there is a lift. If no signal is output, it can be determined that the recording plate is not in contact with the detection plate 3. In this case, it can be seen that there is only unevenness smaller than the distance in the vertical direction to the recording medium initially measured.

  The height of the carriage 1 also affects the image quality. The distance between the nozzle surface of the recording head and the recording medium may or may not be too close, and it is necessary to set a suitable distance. It is necessary to raise and lower the carriage 1 to set a suitable distance. Furthermore, it is preferable that the edge 13 is closer to the platen 6 in the vertical direction than the nozzle surface so that the nozzle surface does not contact the recording medium. Although they may be the same, it is not preferable that the nozzle surface protrudes from the edge 13. The recording head may come into contact with the recording medium before detection.

  The guard 14 is a reinforced portion for protecting the carriage 1 when a jam occurs. A portion that cannot be detected is reinforced by the detection plate 3. The detection plate 3 needs at least a width corresponding to the recording head, preferably a width corresponding to the platen 6. The wiring 8 is an electrical wiring that connects each of the three detection sensors 9 and the control means. Wiring enters the carriage 1 and is connected to the control means. The recording medium detection sensor that detects the lifting of the recording medium includes a detection plate 3 and a detection sensor 9.

  A recording head and a nozzle surface are provided on the side of the carriage 1 facing the platen 6. In the figure, it is not shown because it is behind the detection plate 3.

  The detection plate 3 includes a plurality of slits 4, and a detection sensor 9 is disposed on each plate piece 5. When each plate piece 5 is distorted, the detection sensor 9 arranged corresponding to the plate piece 5 reacts. There is a fixed plate 11 near the end of the slit 4 that divides the detection plate 3, and the detection plate 3 and the detection sensor 9 are fixed to the carriage 1. As a result, detection can be performed for each plate piece 5.

  Also, the width of the plate is wider on the upstream side than the downstream side in the conveyance direction of the recording medium. The upstream side in the conveyance direction of the recording medium is close to the conveyance roller, so that irregularities that cause jamming occur. This is because it is easy to detect early, and the area without the recording head is widened. Further, the detection plate 3 is preferably a PET resin which is resistant to ink and has high workability and durability.

  Here, an example of three sensors has been described, but it is also possible to arrange one sensor with respect to the detection plate 3. By using a plurality of, for example, three sensors, if any one of them reacts, control such as stopping the carriage 1 can be performed. Depending on the position at which the sensor is arranged with respect to the detection plate 3, a time lag may occur, and a plurality of sensors are arranged to accelerate the reaction.

  The recording range 15 of the recording head is equal to the length of the nozzle row that ejects ink. The nozzles are arranged in a row along the conveyance direction of the recording medium. Recording can be performed with the width of the nozzle row. The detection plate 3 is arranged on the upstream side in the conveyance direction of the recording medium so as to be able to detect the position outside the recording range 15.

  FIG. 2 is a block diagram of the printer. The control means 20 is a control circuit including a CPU that executes processing operations such as calculation, control, determination, and setting. The control means 20 operates according to a control program stored in the ROM 21. The RAM 22 is used as a buffer for recording data, a work area for processing by the control means 20, and a memory for temporarily storing data. The carriage movement motor drive circuit 24 operates under the control of the control means 20 and drives a motor that moves the carriage 1. The carriage position detection sensor 25 is a sensor that detects the position of the carriage 1. The control means 20 acquires the output of the carriage position detection sensor 25, calculates it, and uses it for various controls. For example, the carriage position detection sensor 25 is configured to detect a scale of a linear scale arranged along a rail on which the carriage 1 is movably fixed with a linear sensor. The position of the carriage 1 can be calculated and acquired based on the sensor output. Based on this position, the carriage 1 can be controlled to move.

  The head drive circuit 26 is controlled by the control means 20. The recording head is operated via the head driving circuit 26. When a plurality of recording heads are mounted, the control unit 20 and the head driving circuit 26 can drive each recording head individually. The head drive circuit 26 generates ink ejection timing or non-ejection timing for each recording head based on information input from the control means 20 and drives the recording head. This timing is calculated based on the position of the carriage 1 acquired by the carriage position detection sensor 25. Ink ejection and non-ejection can be controlled corresponding to each nozzle. When ink is ejected, an on waveform is generated, and when ink is not ejected, an off waveform is generated and transferred to each recording head. The ejection timing is determined according to the position of the carriage 1.

  From the movement time of the carriage 1 and the position information acquired from the carriage position detection sensor 25, the movement speed of the carriage 1 can be calculated. Usually, ink is ejected while controlling the movement speed of the carriage 1 to be constant. By setting the ink ejection timing to a constant period, the interval between dots to be recorded can be made constant. The ejection timing is determined in advance so as to be optimal depending on the distance between the recording medium and the nozzle surface of the recording head. The relationship between the distance and the discharge timing is stored in the ROM 21 in advance, and the control unit 20 measures the distance as necessary, and determines the discharge timing using the relationship stored in the ROM 21 according to the measured distance. To do. The ROM 21 stores stepwise distances and ejection timing data corresponding to the distances in association with each other.

  The recording medium transport unit 27 operates under the control of the control unit 20. The recording medium transport unit 27 includes a transport roller and a motor that drives the transport roller. The recording medium is conveyed by operating the conveying roller.

  The recording medium detection sensor 29 includes the detection plate 3 and the detection sensor 9, detects an abnormal conveyance state such as the floating of the recording medium from the platen 6, and outputs it to the control means 20. The control means 20 performs various calculations and controls based on the detection results from the recording medium detection sensor 29.

  The distance sensor 12 is fixed to the carriage 1 and can measure a moving distance until the platen 6 comes into contact with the tip of a terminal that expands and contracts. Thereby, the distance from the reference position to the object can be measured. The distance sensor 12 operates under the control of the control means 20.

  The operation panel 23 operates under the control of the control means 20. The operation panel 23 is provided with an LCD panel, can perform various displays, and has a keyboard for input.

  The carriage lifting / lowering means 28 can move the carriage 1 in the contact / separation direction with respect to the platen 6. The carriage lifting / lowering means 28 operates under the control of the control means 20. The control means 20 can control the carriage lifting / lowering means 28 based on the distance to the object acquired by the distance sensor 12 to raise and lower the carriage 1 so that the distance between the carriage 1 and the platen 6 is set to a suitable distance. . That is, the interval between the nozzle surface and the platen 6 or the recording medium can be made suitable. By using the carriage lifting / lowering means 28, when the recording medium detection sensor 29 detects the floating of the recording medium, the control means 20 raises the carriage and prevents the recording medium and the recording head from coming into contact with each other. In addition, the ejection timing is varied according to the increased distance to prevent image quality deterioration.

  As the recording medium detection sensor 29, a sensor that contacts the recording medium is used, but a non-contact sensor can also be used. For example, the recording medium may be irradiated with light to detect reflected light that changes according to the distance.

  As described above, each function of the ink jet printer is controlled by the control of the control means 20.

  FIG. 3 is a diagram for explaining the lifting and lowering operation of the carriage. The horizontal axis 30 shows the position of the carriage, and the vertical axis 31 shows the height of the carriage. The positions A and B of the carriage 1 indicate the positions of the edges of the platen 6. A recording area 33 is between the position A and the position B. Position H and position I indicate the edge of the recording medium during recording. Recorded during this time. A position C indicates a position where the recording medium detection sensor 29 detects the recording medium. Position D and position E indicate the folding position of the carriage 1.

  An arrow 34 indicates an example of the traveling direction of the carriage 1. It is assumed that the recording medium and the detection plate 3 are in contact with each other at the position C and the recording medium is detected while the carriage 1 is moving in the arrow direction. As indicated by the line 32 indicating the height of the carriage, scanning at the time of detection is performed as it is, and after the carriage 1 passes the position B, the carriage 1 is raised from the height F to the height G.

  Thereafter, the carriage 1 turns back and performs the next scan. At this time, recording is performed with the ejection timing of the recording head corrected. When the carriage 1 is positioned on the recording medium, the carriage 1 is not moved up and down, and the carriage 1 is moved up and down after going out of the recording area 33.

  FIG. 4 is a diagram for explaining the ink ejection operation. The recording head 40 moves in the direction of the arrow 46. The first recording surface 41 is located closer to the recording head 40 than the second recording surface 42. This indicates that the relative distance between the recording head 40 and the recording medium changes when the carriage 1 is moved up and down. When ink is ejected from the recording head 40 at the same position, the ink lands at a position that differs by a positional deviation amount 45 due to a difference in distance to the recording surface. The difference in landing position affects the image quality. It is necessary to correct this difference. In accordance with a change in the distance from the recording head 40, that is, the nozzle surface, whether the ink ejection timing is advanced or delayed is obtained in advance from experiments or theoretical calculations, and a correction value is created. The ROM 21 stores the discharge timing correction value in association with the distance, and controls to discharge at the timing corrected during recording.

  For example, when the distance changes stepwise with respect to a standard distance, a correction value corresponding to the change is stored. The standard distance is set to 2.0 mm, and the 10-stage carriage 1 can be moved in 0.2 mm steps away from each other. The optimal discharge timing value is stored in the ROM 21 according to the 10-step distance in 0.2 mm steps. Keep it.

  As an example of the operation, when contact of a recording medium is detected, recording is performed as it is in the scanning. When the carriage 1 comes out of the recording area 33, the carriage 1 is first lifted from a standard distance to a position that is separated by a plurality of steps of two or more steps, for example, five steps. A correction value for the ejection timing is acquired from the ROM 21 according to the distance, and is recorded at the corrected ejection timing at the next scanning. This is because if the distance is not separated to some extent, the recording medium is contacted again in the next scanning.

  When further contact of the recording medium is detected in the next scanning, the carriage 1 is further moved up to a position separated by five steps, and a correction value of the ejection timing corresponding to the distance is acquired, and the corrected ejection timing is corrected in the next scanning. Record with.

  Recording is stopped when contact with the recording medium is detected even in a state where the distance is maximum. It is necessary to reset the recording medium.

  If the contact of the recording medium is not detected in the scanning after being raised, the one-step carriage 1 is lowered after the scanning. When the recording medium is detected in the scanning after the lowering, the recording medium is raised by one step after the scanning. Preferably it is raised by two steps. Since the gap between the contact portion of the recording medium and the recording head is equal to or less than one step interval, if it is increased by one step, it may be detected again due to device shake or the like, and it is necessary to give a little allowance.

  The lowering operation of the carriage 1 is not performed from the scanning immediately after the ascending operation, but in the scanning after the recording medium that was in the detection range at the time when the contact of the recording medium was detected was transported out of the detection range. It is preferred that This is because the recording medium is temporarily distorted and may be distorted. When the carriage 1 is lowered in the immediately following scan, the recording medium may be detected, and it can be avoided that the lifting process is frequently performed.

  The recording medium comes into contact with the recording head due to wrinkles generated on the recording medium, which causes jamming. When the lifting of the recording medium is detected, the position of the recording head is raised so as not to come into contact. If the height of the recording head changes, the landing position changes, which affects the image quality. By varying the ejection timing according to the height position of the recording head and correcting the landing position, the influence on the image quality can be suppressed. In addition, it is conceivable to correct the landing position by reducing the ink ejection speed from the recording head. However, if the ejection speed is changed, there is a problem that printing is not stable. Although it is conceivable to change the speed of the carriage, there is a problem that the recording speed becomes slow. It is most preferable to correct the discharge timing. Also, if the height is changed during carriage scanning, it is difficult to correct the ejection timing, and the processing load increases, and the image quality may be adversely affected. It is preferable to change the height before starting and further change the discharge timing.

FIG. 5 is a diagram illustrating an overview of the entire printer. The ink jet printer 50 records an image by discharging ink onto a recording medium adsorbed on the platen 6 while reciprocating the carriage 1 over the platen 6. The platen 6 is a flat plate, pores are formed in the plate, a suction chamber is arranged on the back side, air is drawn in, and the recording medium is adsorbed by the force and supported flat. A paper guide 7 is disposed in the conveyance direction of the recording medium on the platen 6 to heat the discharged recording medium and promote ink fixing. Further, a fan heater 51 is provided at a position facing the paper guide 7 and promotes fixing of ink by heating or blowing.
A plurality of conveying rollers 52 are positioned along the longitudinal direction of the platen 6 and convey the recording medium. The recording medium is conveyed while being supported by the platen 6 and the paper guide 7. Unevenness caused by distortion or bending of the recording medium can be detected, and control can be performed so that the recording head mounted on the carriage 1 does not contact the recording medium.

  The present invention can be applied to an ink jet printer.

DESCRIPTION OF SYMBOLS 1 Carriage 2 Elevating mechanism 3 Detection board 4 Slit 5 Plate piece 6 Platen 7 Paper guide 12 Distance sensor 13 Edge 20 Control means 25 Carriage position detection sensor 26 Head drive circuit 28 Carriage raising / lowering means 29 Recording medium detection sensor 50 Inkjet printer

Claims (4)

A plurality of nozzles, and a recording head that discharges ink from the nozzles toward a recording medium;
A platen that supports the recording medium;
Conveying means for conveying the recording medium;
A carriage mounted with the recording head and reciprocating in a scanning direction intersecting a conveying direction of the recording medium;
A recording medium detection sensor for detecting lifting of the recording medium conveyed on the platen from the platen;
Elevating means for moving the carriage in a direction in which the carriage moves toward and away from the platen along the ink ejection direction of the recording head;
Control means for controlling the operation of the carriage and the recording head based on the detection result of the recording medium detection sensor;
In an inkjet printer that records an image on the recording medium supported by the platen,
When the recording medium detection sensor detects lifting of the recording medium from the platen, the control means controls the elevating means to move the carriage a predetermined amount in a direction away from the platen, and further An inkjet printer that performs control to change the ejection timing of the ink from the recording head in accordance with the amount.   2. The ink jet printer according to claim 1, wherein the raising and lowering of the carriage by the raising and lowering means is performed in a state where the carriage moves outside the platen area and the reciprocating movement is stopped.   The movement of the carriage in the contact / separation direction by the lifting / lowering means is controlled in steps when the movement distance is controlled stepwise and the recording medium detection sensor detects the lifting of the recording medium from the platen. The inkjet printer according to claim 1, wherein the inkjet printer is moved in a direction away from the platen in two or more steps.   When the carriage is moved in a direction away from the platen in two or more steps and recording is continued, and the recording medium detection sensor does not detect the lifting of the recording medium from the platen, the carriage is The inkjet printer according to claim 3, wherein the inkjet printer is moved stepwise in a direction approaching the platen.

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