JP2013223978A - Printing apparatus and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a printing time.SOLUTION: A printing apparatus includes: a conveying mechanism to convey a medium in a conveying direction; a carriage including nozzles for ejecting liquid to be movable back and forth in a moving direction perpendicular to the conveying direction; and a control unit to alternately perform an ejecting operation of ejecting the liquid from the nozzles while moving the carriage in the moving direction based on a speed profile including a constant speed range and an acceleration/deceleration range, and a conveying operation of controlling the conveying mechanism to convey the medium in the conveying direction in intervals between the ejecting operations, then, print an image on the medium. The printing apparatus includes an acceleration/deceleration range printing mode of ejecting the liquid from the nozzles in the acceleration/deceleration range. When changing the moving direction of the carriage, the control unit determines whether an acceleration/deceleration range non-printing time in which the liquid is not ejected from the nozzles in the acceleration/deceleration range is equal to or shorter than a medium conveying time by the conveying operation, and when it is determined that the acceleration/deceleration range non-printing time is shorter than the conveying time, makes the moving distance of the carriage longer so that the acceleration/deceleration range non-printing time may become equal to or longer than the conveying time.

Description

  The present invention relates to a printing apparatus and a printing method.

  An image is printed on the medium by alternately repeating a discharge operation for discharging liquid from the nozzle to the medium while moving the carriage having the nozzle in the movement direction, and a transport operation for transporting the medium in the transport direction between the discharge operations. A printing apparatus is known. In such a printing apparatus, the carriage is normally driven based on a speed profile having an acceleration area, a constant speed area, and a deceleration area (hereinafter, the acceleration area and the deceleration area are also referred to as acceleration / deceleration areas). Also known is a printing apparatus having an acceleration / deceleration printing mode in which printing is performed by discharging liquid from the nozzles of a carriage even in this acceleration / deceleration region (see, for example, Patent Document 1).

JP 2004-58543 A

In the printing apparatus as described above, when the carriage moves in the moving direction, the discharge operation ends (the ink discharge ends), and the transport operation starts. When the transport operation ends, the next discharge operation The printing time can be shortened by starting the process (starting ink ejection).
However, when the acceleration / deceleration printing mode is executed, there is a problem that it may be difficult to shorten the printing time if the time for carrying the carrying operation (carrying time) is long.
Accordingly, an object of the present invention is to shorten printing time (improve throughput).

  A main invention for achieving the above object includes a transport mechanism that transports a medium in a transport direction, a nozzle that discharges a liquid, a carriage that can reciprocate in a moving direction that intersects the transport direction, and a constant speed region. And a discharge operation for discharging the liquid from the nozzle while moving the carriage in the moving direction based on a speed profile having an acceleration / deceleration region, and controlling the transport mechanism between the discharge operations to control the medium. And a control unit that alternately executes a transport operation for transporting in the transport direction and prints an image on the medium, wherein the acceleration / deceleration printing discharges the liquid from the nozzles in the acceleration / deceleration region. Mode, and the control unit is in the acceleration / deceleration area when the carriage movement direction is switched, and the acceleration / deceleration non-printing time during which the liquid is not discharged from the nozzle , It is determined whether it is less than the transport time of the medium by the transport operation, and if it is determined that the acceleration / deceleration non-printing time is less than the transport time, the acceleration / deceleration non-printing time is The printing apparatus is characterized in that the moving distance of the carriage is increased so as to be more than time.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

FIG. 2 is a diagram for describing an internal configuration of a printer according to the present embodiment. FIG. 2 is a side view for explaining the printer 10 in the present embodiment. It is a figure for demonstrating the signal output by the linear encoder 50. FIG. 3 is a block diagram illustrating a configuration of a portion that controls driving of a CR motor 22 in a control unit 100. FIG. 4 is a diagram illustrating an example of a speed profile of a carriage 21. FIG. 6A and 6B are explanatory diagrams of ink landing positions in the constant speed region and the acceleration / deceleration region. It is explanatory drawing about the timing of discharge operation and conveyance operation in a comparative example. It is explanatory drawing about the timing of discharge operation and conveyance operation in this embodiment. FIG. 10 is a flowchart showing processing for optimizing the movement distance of the carriage 21.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

Based on a speed profile having a transport mechanism that transports a medium in a transport direction, a carriage that has a nozzle that discharges liquid, and that can reciprocate in a moving direction that intersects the transport direction, and a constant speed region and an acceleration / deceleration region. A discharge operation for discharging the liquid from the nozzle while moving the carriage in the movement direction and a transfer operation for controlling the transfer mechanism between the discharge operations to transfer the medium in the transfer direction are alternately performed. A control unit that executes and prints an image on the medium, and has an acceleration / deceleration printing mode in which the liquid is ejected from the nozzle in the acceleration / deceleration region, and the control unit includes: When the carriage movement direction is switched, the acceleration / deceleration non-printing time that is in the acceleration / deceleration area and does not discharge the liquid from the nozzles is determined when the medium is transported by the transport operation. If the acceleration / deceleration non-printing time is determined to be less than the conveyance time, the carriage is moved so that the acceleration / deceleration non-printing time is equal to or longer than the conveyance time. A printing device characterized by increasing the distance becomes clear.
According to such a printing apparatus, it is possible to reduce the carriage standby time during the transport operation by increasing the carriage movement distance, and to reduce the printing time in the acceleration / deceleration area (constant speed area). Increase the printing time in the printer). Therefore, the printing time can be shortened (throughput can be improved).

In such a printing apparatus, when the control unit determines that the acceleration / deceleration non-printing time is equal to or longer than the transport time, the control unit may move the carriage by a reference moving distance.
According to such a printing apparatus, the moving distance of the carriage can be easily optimized.

In this printing apparatus, it is preferable that the control unit determines whether the acceleration / deceleration non-printing time is less than the transport time for each ejection operation.
According to such a printing apparatus, it is possible to cope with a printing method in which the medium conveyance amount (conveyance time) is different between the respective ejection operations.

In this printing apparatus, when the control unit determines that the acceleration / deceleration non-printing time is less than the conveyance time, the acceleration / deceleration non-printing time is set to be the same as the conveyance time. It is desirable to adjust the moving distance of the carriage.
According to such a printing apparatus, it is possible to further shorten the printing time.

In such a printing apparatus, it is desirable to lengthen the time for performing the ejection operation in the constant speed region and shorten the time for performing the ejection operation in the acceleration / deceleration region by increasing the moving distance of the carriage. .
According to such a printing apparatus, the image quality (print quality) can be improved.

In addition, in a printing apparatus having a transport mechanism that transports a medium in a transport direction, and a carriage that has a nozzle that discharges a liquid and is movable in a movement direction that intersects the transport direction.
Based on a speed profile having a constant speed region and an acceleration / deceleration region, the transport mechanism is controlled between the discharge operation for discharging the liquid from the nozzle while moving the carriage in the intersecting direction, and the discharge mechanism. A printing method for performing printing on the medium by alternately performing a transport operation for transporting the medium in the transport direction,
Having an acceleration / deceleration printing mode for discharging the liquid from the nozzle in the acceleration / deceleration region;
Whether the acceleration / deceleration non-printing time in which the liquid is not ejected from the nozzles is less than the transport time of the medium in the transport operation when the carriage movement direction is switched. Judging,
If it is determined that the acceleration / deceleration non-printing time is shorter than the transport time, the moving distance of the carriage is increased so that the acceleration / deceleration area non-printing time is equal to or longer than the transport time;
A printing method characterized by having:

=== Embodiment ===
Hereinafter, an inkjet printer (printer 10) will be described as an example of a printing apparatus. In the following description, the lower side refers to the side where the printer 10 is installed, and the upper side refers to the side away from the installed side. Further, the side on which the paper P as a medium is supplied will be described as a feeding side (rear end side), and the side on which the paper P is discharged will be described as a paper discharge side (front side).

<< General configuration of the printer 10 >>
FIG. 1 is a diagram for explaining the internal configuration of the printer 10 according to the present embodiment. FIG. 2 is a side view for explaining the printer 10 in the present embodiment. As shown in FIG. 1, the printer 10 includes a housing unit (not shown), a carriage drive mechanism 20, a paper transport mechanism 30, a rotary encoder 40, a linear encoder 50, and a control unit 100. .

  The carriage drive mechanism 20 includes a carriage 21, a carriage motor 22 (hereinafter also referred to as a CR motor 22), a belt 23, a gear pulley 24, a driven pulley 25, and a carriage shaft 26. The carriage 21 can be loaded with ink cartridges 27 for each color. As shown in FIGS. 1 and 2, a print head 28 capable of ejecting ink droplets is provided on the lower surface of the carriage 21. The belt 23 is an endless belt, and a part of the belt 23 is fixed to the back surface of the carriage 21. The belt 23 is stretched by a gear pulley 24 and a driven pulley 25. In addition, the inner peripheral surface of the belt 23 and the outer periphery of the gear pulley 24 are respectively gear-shaped, and the gear pulley 24 is rotated by the rotation of the CR motor 22 in a state where the gears mesh with each other. The belt 23 rotates and the carriage 21 moves along the carriage shaft 26. The direction in which the carriage 21 moves (hereinafter also referred to as the moving direction) is a direction that intersects (generally orthogonal) with the conveyance direction of the paper P described later. One end side in this moving direction (home position side, for example, the right side in FIG. 1) is also referred to as the home side, and the other end side (for example, the left side in FIG. 1) is also referred to as the full side. Further, regarding the movement of the carriage 21, the movement path from the home side to the full side is referred to as the forward path, and the movement path from the full side to the home side is referred to as the return path. In the printer 10 of this embodiment, the moving range of the carriage 21 (the moving distance between the home side and the full side) is changed within a predetermined range wider than the width of the print area on the medium (paper P). (It will be described later).

  The above-described carriage 21 (more specifically, the print head 28) is provided with a nozzle row (not shown) corresponding to each ink, and a nozzle element (not shown) is included in each nozzle constituting the nozzle row. Is arranged. By operating the piezo element, it is possible to eject ink droplets from the nozzles at the end of the ink passage.

  The paper transport mechanism 30 includes a transport motor 31 (hereinafter also referred to as a PF motor 31) for transporting a medium such as paper P, and a paper feed roller 32 corresponding to the feeding of plain paper or the like. Further, a PF roller pair 33 for conveying / clamping the paper P is provided on the paper discharge side of the paper supply roller 32. The PF roller pair 33 includes a PF drive roller 33a and a driven roller 33b. The driving force from the PF motor 31 is transmitted to the PF driving roller 33a.

  Further, on the paper discharge side of the PF roller pair 33, the platen 34 and the above-described print head 28 are disposed so as to face each other vertically. The platen 34 supports the paper P conveyed below the print head 28 by the PF roller pair 33 from below. Further, a discharge roller pair 35 similar to the above-described PF roller pair 33 is provided on the discharge side of the platen 34. The paper discharge roller pair 35 includes a paper discharge driving roller 35a and a driven roller 35b. Of this pair of paper discharge rollers 35, the drive force from the PF motor 31 is transmitted to the paper discharge drive roller 35a together with the PF drive roller 33a. In the present embodiment, the CR motor 22 of the carriage drive mechanism 20 and the PF motor 31 of the paper transport mechanism 30 are DC motors, but may be other types of motors.

  As shown in FIG. 1, the rotary encoder 40 includes a disk scale 41 and a rotary sensor 42. Among these, the disk-shaped scale 41 has a light-transmitting part that transmits light and a light-blocking part that blocks light transmission at regular intervals along the circumferential direction. The disc scale 41 is rotated by the PF motor 31.

  The rotary sensor 42 includes a light emitting element (not shown) and a light receiving element (not shown) as main components. Among these, the light emitting element is composed of a member capable of emitting light, such as a light emitting diode. Further, a collimator lens (not shown) is interposed between the light emitting element and the light receiving element. Then, the light emitted from the light emitting element is shaped into parallel light by passing through the collimator lens, and then incident on the disk-like scale 41.

  The light input to the light receiving element is converted into an electrical signal by performing a predetermined photoelectric conversion, and then processed in a signal processing circuit (not shown), and the processed signal is output to a comparator (not shown).

  The linear encoder 50 includes a linear scale 51 extending along the moving direction (sub-scanning direction) of the carriage 21 and a photo sensor (linear sensor 52) similar to the rotary encoder 40 described above. Since the linear encoder 50 has the same configuration as that of the rotary encoder 40 except that the linear scale 51 has a long shape, a detailed description thereof will be omitted.

  FIG. 3 is a diagram for explaining a signal output by the linear encoder 50. The comparator compares each input signal and outputs a pulse signal (A-phase ENC signal, B-phase ENC signal) as shown in FIG. Here, the output A-phase ENC signal and B-phase ENC signal differ from each other by 90 degrees. Therefore, when the CR motor 22 is in a forward rotation state (for example, when the carriage 21 is moved in the forward direction), the phase of the A-phase ENC signal advances by 90 degrees relative to the B-phase ENC signal. When the CR motor 22 is in the reverse rotation state (for example, when the carriage 21 is moved in the backward direction), the phase of the A-phase ENC signal is delayed by 90 degrees from that of the B-phase ENC signal.

  Based on the signal output from the linear encoder 50, the control unit 100, which will be described later, performs calculations, whereby the current speed and current position of the carriage 21 can be calculated. Similarly, regarding the conveyance of the paper P, the current speed and the current position of the paper P can be calculated by the control unit 100 performing calculations based on the signal output from the rotary encoder 40.

  Furthermore, the printer 10 includes other sensors such as a paper width detection sensor that detects the width of the paper P, and a gap detection sensor that detects the distance between the print head 28 and the platen 34.

  The control unit 100 is a part that performs various controls on the printer 10. The control unit 100 receives output signals such as the rotary sensor 42, the linear sensor 52, a paper width detection sensor (not shown), a gap detection sensor (not shown), and a power switch for turning on / off the printer 10. .

  As shown in FIG. 1, the control unit 100 includes a CPU 101, a ROM 102, a RAM 103, a PROM 104, an ASIC 105, a motor driver 106, and the like, and these are connected via a transmission path 107 such as a bus. The operation in the present embodiment is realized by the cooperation of these hardware and software and / or data stored in the ROM 102 or PROM 104.

≪About printing operation≫
The control unit 100 of the printer 10 according to the present embodiment causes the paper transport mechanism 30 to transport the paper P in the transport direction between the ejection operation of ejecting ink from the nozzles of the head 28 while moving the carriage 21 in the movement direction. The carrying operation to carry is carried out alternately. Thus, an image is printed on the paper P. Note that the printer 10 of the present embodiment ejects ink when the carriage 21 moves from the home side to the full side (outward path) and when it moves from the full side to the home side (return path). That is, the printer 10 of this embodiment performs bidirectional printing.

≪About CR motor drive control≫
FIG. 4 is a block diagram illustrating a configuration of a portion of the control unit 100 that controls driving of the CR motor 22. As shown in FIG. 4, the control unit 100 includes a position calculation unit 121, a speed calculation unit 122, a first subtraction unit 123, a target speed generation unit 124, a second subtraction unit 125, a proportional element 126, An integration element 127, a differentiation element 128, an addition unit 132, and a PWM signal output unit 133 are provided.

  The position calculation unit 121 calculates the amount of movement of the carriage 21 by counting the edges of the rectangular wave output signal (see FIG. 3) input from the linear sensor 52. The speed calculator 122 counts the edges of the rectangular wave output signal input from the linear sensor 52 and also receives a signal related to time (period) measured by a timer (not shown). Then, the speed (movement speed) of the carriage 21 is calculated based on the counted edge and time (cycle).

  The first subtraction unit 123 calculates a position deviation by subtracting the current position from the target position based on the information regarding the movement amount (current position) output from the position calculation unit 121 and the information regarding the target position. Information on the positional deviation output from the first subtraction unit 123 is input to the target speed generation unit 124. The target speed generation unit 124 refers to the speed profile and outputs information related to the target speed according to the position deviation. The speed profile will be described later.

The second subtracting unit 125 subtracts the current moving speed (current speed) of the CR motor 22 from the target speed, calculates a speed deviation ΔV, and outputs it to the proportional element 126, the integral element 127, and the differential element 128, respectively. The proportional element 126, the integral element 127, and the differential element 128 calculate the following proportional control value QP, integral control value QI, and differential control value QD based on the input speed deviation ΔV.
QP (j) = ΔV (j) × Kp (Expression 1)
QI (j) = QI (j−1) + ΔV (j) × Ki (Expression 2)
QD (j) = {ΔV (j) −ΔV (j−1)} × Kd (Formula 3)
Here, j is time, Kp is a proportional gain, Ki is an integral gain, and Kd is a differential gain.

  The adder 132 adds the control values output from the proportional element 126, the integral element 127, and the derivative element 128, and outputs the sum of the control values obtained by the addition to the PWM signal output unit 133. The PWM signal output unit 133 outputs a PWM signal having a duty ratio obtained by converting the sum of the control values supplied from the adding unit 132.

  The motor driver 106 drives the PF motor 31 by PWM control based on the PWM signal output from the PWM signal output unit 133.

  With the above configuration, the control unit 100 controls the driving of the CR motor 22 according to a predetermined speed profile.

<About movement of carriage 21>
FIG. 5 is a diagram illustrating an example of the speed profile of the carriage 21. In the figure, the horizontal axis is time, and the vertical axis is speed.

As shown in the figure, the speed profile of the CR motor 22 in the present embodiment includes an acceleration region in which acceleration is performed from the stopped state to a predetermined speed, a constant speed region in which the predetermined speed is maintained, and a deceleration region in which the vehicle is decelerated from the predetermined speed to the stopped state. . The CR motor 22 is controlled to be driven with such a speed profile, and moves the carriage 21 in the width direction (movement direction) of the medium based on the speed profile. The printer 10 of the present embodiment has a printing mode (acceleration / deceleration printing mode) in which ink is ejected from the nozzles and printing is performed even in the acceleration / deceleration region (acceleration region and deceleration region). However, in the acceleration / deceleration area, it is difficult to control the ink landing position as compared with the constant speed area, and there is a possibility that the image quality may be lowered. FIGS. It is explanatory drawing about a landing position. 6A is an explanatory diagram when the carriage 21 moves in the forward direction (from the home side to the full side), and FIG. 6B is an explanatory diagram when the carriage 21 moves in the backward direction (from the full side to the home side). FIG. 6A and 6B, it is assumed that ink is ejected from the carriage 21 at the position of the scale. Note that the scales are equally spaced, that is, ink is ejected each time a certain number of pulse signals are output from the linear encoder 50.

  In the figure, each downward arrow represents a flight trace of ink particles. The tip of each arrow represents the actual landing position of each ink on the medium. While the carriage 21 is moving at a low speed, the inclination of the arrow indicating the flight trace of the ink particles is small. As the speed of the carriage 21 increases, the inclination of the arrow increases. As the carriage 21 decelerates, the slope of the arrow decreases again (approaches vertical). In the figure, the lower straight line represents the target position where the ink particle should land by a black dot.

  If ink is ejected from the nozzle every time the carriage 21 moves a certain distance, the ink landing position becomes sparse during the acceleration of the carriage 21, the landing position becomes constant during the constant speed movement, and during the deceleration. Shows that the landing positions are dense. Further, as a result of the variation in the landing position, it can be understood that the ink is landed accurately at the target position only while the speed of the carriage 21 reaches a constant speed. It can also be seen from FIGS. 6A and 6B that the ink particle landing positions during acceleration / deceleration do not coincide with each other on the forward path and the backward path.

  In order to reduce the deviation of the ink landing position in such an acceleration / deceleration region, for example, the ink ejection timing from the nozzles may be controlled. In the printer 10 of this embodiment, the deterioration of the image quality is prevented by controlling the ejection timing of the ink from the nozzles in the acceleration / deceleration region. However, even when the ejection timing is controlled in this way, it is difficult to land the ink accurately at the target position as in the constant speed region. That is, in the acceleration / deceleration range, there is a higher risk of image quality deterioration than in the constant speed range.

≪Discharge operation and transfer operation timing≫
In the printer 10 of the present embodiment, as will be described later, when the carriage 21 moves in the moving direction, the discharge operation ends (the ink discharge ends) and the transfer operation starts, and the transfer operation ends. In addition, the printing time is further shortened by starting the next discharge operation (starting ink discharge). That is, if the ink is not ejected even when the carriage 21 is moving, the printing time is shortened by performing the transport operation during that period.

<Comparative example>
FIG. 7 is an explanatory diagram regarding the timing of the ejection operation and the transport operation in the comparative example. The drawing shows the drive timing (time and speed) of the carriage 21 and the PF drive roller 33a when the carriage 21 reciprocates in the forward and backward directions.

  In FIG. 7, the upper diagram shows the driving of the carriage 21, the horizontal axis shows time, and the vertical axis shows the speed of the carriage 21. 7 is a diagram illustrating the driving of the PF driving roller 33a. The horizontal axis represents time, and the vertical axis represents the driving speed of the PF driving roller 33a (that is, the conveyance speed of the paper P). .

  First, the control unit 100 starts to move the carriage 21 from the home position (home side end) at time t0, and increases the speed at a constant rate (acceleration range) until time t2. At this time, the carriage 21 enters the printing region at time t1, and the control unit 100 starts ejecting ink from the nozzle toward the paper P. Note that the times t0 to t1 correspond to acceleration / deceleration areas (acceleration areas in this case) and acceleration / deceleration non-printing times during which ink is not ejected, and the movement distance (area in the drawing) of the carriage 21 at this time. Is a moving distance E. Also, printing is performed in the acceleration region at times t1 to t2.

  From time t2 to time t3, the speed of the carriage 21 is constant (constant speed range), and the control unit 100 ejects ink from the nozzles of the carriage 21 that moves at a constant speed.

  Thereafter, the control unit 100 decreases the speed at a constant rate from time t3 (deceleration range), and at time t5, the carriage 21 reaches the full stop position. In this deceleration area, as shown in the drawing, the carriage 21 reaches the end of the printing area at time t4, and the ink ejection ends. That is, printing in the deceleration region is performed at times t3 to t4. Therefore, times t1 to t4 in the figure are times during which printing is performed on the print area of the paper P, and the movement distance (area of the hatched portion in the figure) of the carriage 21 at this time is the movement distance A. Times t4 to t5 correspond to acceleration / deceleration areas (deceleration areas in this case) and acceleration / deceleration non-printing times during which ink is not ejected. The movement distance (area in the drawing) of the carriage 21 at this time Is a moving distance C.

  Further, as shown in the lower side of FIG. 7, the control unit 100 immediately drives the PF drive roller 33 a to drive the paper when the ink discharge is completed at time t <b> 4 (even though the carriage 21 is moving). The conveyance of P is started. By doing so, the printing speed is increased. More specifically, the control unit 100 increases the speed (rotational speed) of the PF driving roller 33a at a constant rate to a maximum speed at time t4, and after reaching the maximum speed, at a constant rate until time t7. Decreasing speed. As a result, the paper P is transported in the transport direction by a certain amount. That is, the transport operation is performed from time t4 to time t7, and the time of this period becomes the transport time of the paper P.

  Further, the control unit 100 starts to start moving the carriage 21 from the full side toward the home side (in the return path) at time t6 before time t7 when the conveyance of the paper P by the PF drive roller 33a ends. . Then, at time t7 when the conveyance of the paper P is completed, the ejection of ink is started while the speed of the carriage 21 is accelerated. Note that the control unit 100 drives the carriage 21 so that the speed at each position in the movement direction is the same as that of the forward path on the return path (so as to be symmetric with the speed change of the forward path). For example, the times t6 to t7 correspond to the times t4 to t5 of the forward path (acceleration / deceleration non-printing time), and the movement distance of the carriage 21 at this time is the same as the movement distance of the forward path (movement distance C). In the return path, printing (ink ejection) is performed from t7 to t10 in the figure, and the movement distance of the carriage 21 at this time is the same movement distance A as that of the forward path. Times t10 to t11 correspond to forward times t0 to t1 (acceleration / deceleration non-printing time), and the movement distance of the carriage 21 at this time is the movement distance E.

  As shown in the figure, in this comparative example, the time from when the carriage 21 starts moving from the home position to when it returns to the home position (time required for the carriage 21 to reciprocate: times t0 to t11) is referred to as TCA. Further, the transport time (time t4 to t7) of the paper P is called TPF.

  As described above, in the comparative example, the conveyance of the paper P is started at the end of printing (time t4) before the time t5 when the carriage 21 stops. In addition, the carriage 21 starts to move at time t6 prior to time t7 when the conveyance of the paper P ends, and printing starts at time t7. In this way, the printing time is shortened. However, in this comparative example, the carriage 21 is stopped on the full side from the time t5 to the time t6, and there is a period in which the carriage 21 is in a standby state during the carrying operation. For this reason, it is difficult to further shorten the printing time. Therefore, in this embodiment, the printing time is further shortened compared to this comparative example.

<This embodiment>
FIG. 8 is an explanatory diagram regarding the timing of the discharge operation and the transport operation in the present embodiment. The drawing shows the drive timing (time and speed) of the carriage 21 and the PF drive roller 33a when the carriage 21 reciprocates in the forward direction and the backward direction as in the comparative example (FIG. 7). That is, the upper diagram in FIG. 8 is a diagram showing the drive of the carriage 21, the horizontal axis shows time, and the vertical axis shows the speed of the carriage 21. 8 is a diagram illustrating the driving of the PF driving roller 33a. The horizontal axis represents time, and the vertical axis represents the driving speed of the PF driving roller 33a (that is, the conveyance speed of the paper P). . In this embodiment, the stop position (home position) on the home side of the carriage 21 is fixed, and only the stop position on the full side is changed. In each figure, the scale of the time axis is the same as that in the comparative example, and the same symbol is assigned to the same time. For example, the time for transporting the paper P (time t4 to time t7) is the same as that in the comparative example (FIG. 7).

  First, the control unit 100 starts moving the carriage 21 from the home position (home side) at time t0 ′ and increases the speed at a constant rate (acceleration range) until time t2 ′. In the present embodiment, the drive start time (time t0 ′) of the carriage 21 is later than the time t0 of the comparative example. This is because, in this embodiment, as will be described later, the time required for the carriage 21 to reciprocate can be shortened compared to the comparative example. Note that the rate of change in speed (inclination) in the acceleration region and the deceleration region in this embodiment is the same as in the comparative example.

  Thereafter, the carriage 21 enters the printing region at time t1 ′, and the control unit 100 starts ejecting ink from the nozzle toward the paper P. Times t0 ′ to t1 ′ correspond to acceleration / deceleration non-printing time during which no ink is discharged in the acceleration / deceleration region (acceleration region in this case), and the movement distance (area in the drawing) of the carriage 21 at this time. Is the same movement distance E as in the comparative example. Also, printing is performed in the acceleration region from time t1 ′ to t2 ′.

  From time t2 ′ to time t3 ′, the speed of the carriage 21 is constant (constant speed), and the control unit 100 ejects ink from the nozzles of the carriage 21 that moves at a constant speed. However, the printing speed in the constant speed region (time t2 ′ to t3 ′) in this embodiment is longer than the printing time in the constant speed region (time t2 to t3) in the comparative example.

  Thereafter, the control unit 100 decreases the speed at a constant rate from time t3 ′ (deceleration range), and at time tc, the carriage 21 reaches the full stop position. In this deceleration area, the carriage 21 reaches the end of the printing area at time t4, and the ink ejection is finished. That is, printing is performed in the deceleration region at times t3 ′ to t4.

  Times t1 ′ to t4 in the figure are times during which printing is performed on the print area of the paper P, and the movement distance of the carriage 21 at this time (the area of the shaded area in the figure) is the movement distance B. The moving distance B is the same distance as the moving distance A of the comparative example. Further, when the speed of the carriage 21 when passing through the end portion of the printing area (time t4 when the ink ejection is finished) is compared with the comparative example (FIG. 7), the present embodiment is more at the time t4 than the comparative example. It can be seen that the moving speed of the carriage 21 is fast. Times t4 to tc correspond to acceleration / deceleration non-printing time during which no ink is ejected in the acceleration / deceleration region (in this case, the deceleration region). The distance is D. As can be seen from the figure, the movement distance D is larger than the movement distance C of the comparative example. That is, in this embodiment, the stop position of the carriage 21 is extended to the full side so that the movement distance of the carriage 21 is longer than that of the comparative example.

  In this embodiment (FIG. 8), the control unit 100 immediately reverses the moving direction of the carriage 21 from the full side to the home side when the carriage 21 reaches the full-side stop position (at time tc). Thus, the movement of the carriage 21 is started. Then, ink ejection is started from the accelerating carriage 21 at time t7 when the conveyance of the paper P is stopped. Also in the present embodiment, the control unit 100 drives the carriage 21 so that the speed at each position in the movement direction is the same as that of the forward path on the return path (so as to be symmetric with the speed change of the forward path). For example, time tc to t7 is an acceleration region corresponding to the forward deceleration region (time t4 to tc), and the moving distance at this time is the same as the moving distance from time t4 to tc (moving distance D). In the return path, printing (ink ejection) is performed from t7 to t10 ′ in the figure, and the movement distance of the carriage 21 at this time is the same movement distance B as that of the forward path. Times t10 ′ to t11 ′ correspond to acceleration / deceleration non-printing time, and the movement distance of the carriage 21 at this time is the movement distance E.

  Also, as shown in the figure, in this embodiment, the time from when the carriage 21 starts to move from the home position to when it returns to the home position (time required for the carriage 21 to reciprocate: times t0 ′ to t11 ′) is TCB. Call it. Further, the transport time of the paper P is the same TPF as in the comparative example. Although the transport time is the same TPF as in the comparative example, the movement time TCB of the carriage 21 of the present embodiment is shorter than the movement time TCA of the carriage 21 of the comparative example (TCB <TCA).

  As described above, in this embodiment, the stop position on the full side of the carriage 21 is changed (extended to the full side) so that the moving distance of the carriage 21 becomes long. By doing so, the waiting time on the full side can be reduced, and the printing time in the acceleration / deceleration area can be shortened (printing in the constant speed area can be increased). Thereby, in this embodiment, the time (TCB) required for the reciprocating movement of the carriage 21 can be made shorter than the time (TCA) required for the reciprocating movement of the carriage 21 of the comparative example. Therefore, it is possible to shorten the printing time for TCA-TCB, thereby improving the throughput. In this embodiment, the printing time in the acceleration / deceleration region is shorter than that in the comparative example (the printing time in the constant speed region is long), so that the image quality (printing quality) can be improved as compared with the comparative example. .

  FIG. 9 is a flowchart showing processing for optimizing the movement distance of the carriage 21. In the present embodiment, it is assumed that a plurality of tables in which the relationship (combination) between the non-printing distance and the non-printing time during acceleration / deceleration is set in the control unit 100 (for example, the ROM 102). Each of these tables is assigned a table number (n), and the non-printing distance and non-printing time increase as the table number increases. That is, the minimum table number (n = 1) has the minimum non-printing distance and non-printing time, and this table is used as a reference value for the movement of the carriage 21.

  First, the control unit 100 initializes a table number (n = 0) (S101). Then, the value of n is incremented (S102). For example, in the first case (n = 0), n = 1. Then, the control unit 100 refers to the table of the table number (here, table number 1), calculates the stop position of the carriage 21 from the non-printing distance determined in the table (S103), and the stop position is the carriage position. It is determined whether it is larger than the maximum movement position of 21 (S104). When it is determined that the stop position is equal to or less than the maximum movement position of the carriage 21 (NO in S104), the non-printing time (acceleration / deceleration non-printing time) in the acceleration / deceleration area when switching the movement direction of the carriage 21 is calculated (S105). ). For example, in the case of FIG. 7, the total time of (t5-t4) and (t7-t6) is calculated.

  Then, the control unit 100 determines whether or not the calculated acceleration / deceleration non-printing time is less than the PF driving time (paper P transport time) (S106). If it is determined that the acceleration / deceleration non-printing time is less than the PF driving time (YES in S106), the process returns to step S102, and the table number (n) is incremented. That is, the table number is increased by one, and the non-printing distance and the non-printing time are increased. Thereafter, the same processing is performed. If it is determined in step S106 that the acceleration / deceleration non-printing time is equal to or longer than the PF driving time (NO in S106), the table number is determined (S108). If it is determined in step S104 that the stop position is larger than the maximum movement position of the carriage 21 (YES in S104), the value of n is decremented (S107), and the table number is determined (S108).

  In this example, a plurality of tables are provided in advance and the optimum table is selected from them, but the present invention is not limited to this. For example, two tables, a reference table and a table having a longer movement distance than that (reference), are prepared, and if the determination in step S106 in FIG. If the determination in step S106 is NO, the reference table (the table with the shortest moving distance) may be selected. By doing so, the moving distance of the carriage 21 can be easily optimized.

  As described above, the printer 10 according to the present embodiment includes the transport mechanism 30 that transports the paper P in the transport direction, and the carriage 21 that has nozzles that eject ink and can reciprocate in the movement direction. Yes. Further, the control unit 100 controls the transport mechanism 30 between the discharge operation for discharging ink from the nozzles while moving the carriage 21 in the moving direction based on the speed profile having the constant speed region and the acceleration / deceleration region. Then, an image is printed on the paper P by alternately executing a transport operation for transporting the paper P in the transport direction. Furthermore, the printer 10 of the present embodiment has an acceleration / deceleration printing mode in which ink is ejected from the nozzles in the acceleration / deceleration area, and the control unit 100 is in the acceleration / deceleration area when switching the movement direction of the carriage. In addition, it is determined whether the acceleration / deceleration non-printing time during which ink is not ejected from the nozzles is less than the conveyance time of the paper P. If it is determined that the acceleration / deceleration non-printing time is less than the conveyance time, the table number is changed so that the acceleration / deceleration non-printing time is equal to or longer than the conveyance time, and the movement distance of the carriage 21 is increased. Yes.

  Thus, in this embodiment, the time (TPB) required for reciprocating the carriage 21 can be made shorter than that of the comparative example (TPA), and the printing time can be shortened. In the present embodiment, since the time for printing in the constant speed region is longer than that in the comparative example (the time for printing in the acceleration / deceleration region is short), the image quality (print quality) can be improved.

  In this embodiment, the acceleration / deceleration non-printing time is set to be equal to or longer than the conveyance time. However, if the acceleration / deceleration non-printing time is longer than the conveyance time, a standby time due to the movement of the carriage 21 occurs. End up. Therefore, it is desirable that the acceleration / deceleration non-printing time is equal to the conveyance time as shown in FIG. In this case, the printing time can be shortened most.

  Further, it is desirable to perform the process of optimizing the movement distance of the carriage 21 (FIG. 9) for each ejection operation. For example, there is a printing method in which the transport amount of the paper P is different between the ejection operations. By optimizing the movement distance of the carriage 21 for each ejection operation, it is possible to cope with such a printing method and to shorten the printing time.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About the printer>
In the above-described embodiment, the printer 10 has been described. However, the present invention is not limited to this, and fluids other than ink (liquids, liquids in which particles of functional materials are dispersed, fluids such as gels, etc. ) Can be embodied in a liquid ejecting apparatus that ejects or discharges. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, gas vaporizer, organic EL manufacturing apparatus (especially polymer EL manufacturing apparatus), display manufacturing apparatus, film formation You may apply the technique similar to the above-mentioned embodiment to the various apparatuses which applied inkjet technology, such as an apparatus and a DNA chip manufacturing apparatus. These methods and manufacturing methods are also within the scope of application.

<Discharge method>
In the above-described embodiment, ink is ejected from the nozzles of the print head 28 by a piezo driving method using a piezo element, but the present invention is not limited thereto. For example, a heater method in which ink is heated by a heater and the generated foam force is used, a magnetostriction method in which a magnetostrictive element is used, a mist method in which mist is controlled by an electric field, or the like may be employed.

<About ink>
The ink filled in the cartridge 27 may be mounted with any type of ink such as dye-based ink / pigment-based ink.

<About control of carriage movement distance>
In the above-described embodiment, the stop position of the carriage 21 is changed only on the full side (the moving distance of the carriage 21 is changed), but this is not limitative. For example, the stop position of the carriage 21 may be changed only on the home side (that is, the position of the home position may be changed). Further, the stop positions on both the full side and the home side may be changed.

<About acceleration / deceleration printing>
In the above-described embodiment, ink is ejected even when the carriage 21 is in the acceleration / deceleration region. However, by changing the movement distance of the carriage 21, ink is ejected only in the constant speed region. May be. For example, in FIG. 8, time t3 ′ may overlap with time t4. In this case, the image quality can be further improved.
In the present embodiment, the speed change (inclination) in the acceleration region and the deceleration region is constant, but the present invention is not limited to this. For example, the speed may change in a curved shape.

<Regarding conveyance control of paper P>
In the above-described embodiment, the control unit 100 increases the speed (rotational speed) of the PF drive roller 33a at a constant rate to the maximum speed, and decreases the speed at a constant rate after reaching the maximum speed. This is not a limitation. For example, there may be a region for maintaining the maximum speed (constant speed region). Further, the speed change (slope) may not be constant.

10 Printer,
20 carriage drive mechanism,
21 carriage, 22 CR motor (carriage motor),
23 belt, 24 gear pulley, 25 driven pulley,
26 carriage shaft, 27 cartridge, 28 print head,
30 paper transport mechanism, 31 PF motor, 32 paper feed roller,
33 PF roller pair, 33a PF drive roller, 33b driven roller,
34 platen, 35 paper discharge roller pair,
35a discharge drive roller, 35b driven roller,
40 rotary encoder, 41 disc scale,
42 Rotary sensor, 50 linear encoder,
51 linear scale, 52 linear sensor,
100 control unit, 101 CPU, 102 ROM, 103 RAM,
104 PROM, 105 ASIC, 106 Motor driver,
121 position calculation unit, 122 speed calculation unit, 123 first subtraction unit,
124 target speed generator, 125 second subtractor, 126 proportional element,
127 integral element, 128 differential element,
132 adder, 133 PWM signal output unit

Claims (6)

A transport mechanism for transporting the medium in the transport direction;
A carriage having a nozzle for discharging a liquid and capable of reciprocating in a moving direction intersecting the transport direction;
Based on a speed profile having a constant speed region and an acceleration / deceleration region, the transport mechanism is controlled between the discharge operation for discharging the liquid from the nozzle while moving the carriage in the moving direction, and the discharge mechanism. A controller that alternately executes a transport operation for transporting the medium in the transport direction and prints an image on the medium;
A printing apparatus comprising:
An acceleration / deceleration printing mode for discharging the liquid from the nozzle in the acceleration / deceleration region;
The controller is
Whether the acceleration / deceleration non-printing time during which the liquid is not ejected from the nozzles is less than the transporting time of the medium by the transporting operation when switching the moving direction of the carriage. Judgment,
When it is determined that the acceleration / deceleration non-printing time is less than the transport time, the moving distance of the carriage is increased so that the acceleration / deceleration non-printing time is equal to or longer than the transport time.
A printing apparatus characterized by that. The printing apparatus according to claim 1,
When the control unit determines that the acceleration / deceleration non-printing time is equal to or longer than the transport time, the controller moves the carriage by a reference moving distance.
A printing apparatus characterized by that. The printing apparatus according to claim 1 or 2, wherein
The printing apparatus according to claim 1, wherein the control unit determines whether or not the acceleration / deceleration non-printing time is less than the transport time for each of the ejection operations. The printing apparatus according to any one of claims 1 to 3,
When the control unit determines that the acceleration / deceleration non-printing time is less than the conveyance time, the control unit adjusts the moving distance of the carriage so that the acceleration / deceleration non-printing time is the same as the conveyance time. A printing apparatus characterized by that. The printing apparatus according to any one of claims 1 to 4,
A printing apparatus characterized in that by increasing the movement distance of the carriage, the time for performing the ejection operation in the constant speed region is lengthened, and the time for performing the ejection operation in the acceleration / deceleration region is shortened. In a printing apparatus having a transport mechanism that transports a medium in a transport direction, and a carriage that has a nozzle that discharges a liquid and is movable in a moving direction that intersects the transport direction.
Based on a speed profile having a constant speed region and an acceleration / deceleration region, the transport mechanism is controlled between the discharge operation for discharging the liquid from the nozzle while moving the carriage in the intersecting direction, and the discharge mechanism. A printing method for performing printing on the medium by alternately performing a transport operation for transporting the medium in the transport direction,
Having an acceleration / deceleration printing mode for discharging the liquid from the nozzle in the acceleration / deceleration region;
Whether the acceleration / deceleration non-printing time in which the liquid is not ejected from the nozzles is less than the transport time of the medium in the transport operation when the carriage movement direction is switched. Judging,
If it is determined that the acceleration / deceleration non-printing time is shorter than the transport time, the moving distance of the carriage is increased so that the acceleration / deceleration area non-printing time is equal to or longer than the transport time;
A printing method characterized by comprising:

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