LIQUID EJECTION APPARATUS, CONTROL METHOD THEREOF, AND PROGRAM

Abstract

To realize both dot omission prevention and high-speed recording.SOLUTION: A CPU of a printer acquires an actual moving speed of a head (S2) before a recording process, derives an amount of change in the acquired moving speed from a reference value (S3), and determines a target value Vt of the moving speed, based on the amount of change(S4). In a recording process, the CPU 91 ejects ink toward paper from a nozzle in a constant speed region while moving a head in a scanning direction by means of a moving mechanism so that a moving speed in the constant speed region is made equal to a target value Vt determined in S4.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus that ejects liquid such as ink, and a control method and program thereof. [Background technology]

[0002] The printer (liquid ejection device) described in Patent Document 1 includes a head having nozzles formed therein, a transport mechanism for transporting a sheet (recording medium), and a movement mechanism for moving the head in a scanning direction, and performs a recording process by ejecting ink from the nozzles toward the sheet while moving the head in the scanning direction using the movement mechanism. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-171910 A Summary of the Invention [Problem to be solved by the invention]

[0004] The movable region in which the head can be moved by the movement mechanism includes an acceleration region in which the head accelerates, a deceleration region in which the head decelerates, and a constant speed region between the acceleration region and the deceleration region in the scanning direction in which the head does not accelerate or decelerate. The movement speed of the head in the constant speed region is controlled to a constant target value, but a deviation from the target value occurs due to product variations in the movement mechanism, environmental temperature, environmental humidity, etc. If the deviation is large, the transfer of signals for each ejection cycle (the cycle in which liquid is ejected from the nozzles to the recording medium) is not performed normally, which can result in non-ejection during a certain ejection cycle, resulting in missing dots.

[0005] In order to suppress missing dots, it is conceivable to determine a target value for the head movement speed in the constant speed region so that signal transfer for each ejection cycle is completed even when the movement speed is at its highest value for a predetermined amount of fluctuation (e.g., ±5%). However, as described above, the amount of fluctuation is due to product variations, etc., and if the actual amount of fluctuation is smaller than the predetermined amount of fluctuation (e.g., ±2%), signal transfer can be completed even if the target value is set higher than the target value based on the predetermined amount of fluctuation (e.g., ±5%). In other words, if the target value is determined based on the predetermined amount of fluctuation, the target value will be set too low, which may hinder high-speed recording.

[0006] An object of the present invention is to provide a liquid ejection apparatus that can suppress missing dots and achieve high-speed printing, and a control method and program for the same. [Means for solving the problem]

[0007] A liquid ejection device according to the present invention includes a head having nozzles formed therein, a transport mechanism that transports a recording medium in a transport direction, a movement mechanism that moves the head in a scanning direction perpendicular to the transport direction, a speed sensor that detects the movement speed of the head, and a control unit, wherein a movable region in which the head can be moved by the movement mechanism includes an acceleration region in which the head is accelerated, a deceleration region in which the head is decelerated, and a constant speed region in the scanning direction between the acceleration region and the deceleration region, in which the head is not accelerated or decelerated, and the control unit controls the movement of the head in the scanning direction by the movement mechanism. the moving speed in the constant speed region from the speed sensor; a speed acquisition process, which acquires the moving speed in the constant speed region from the speed sensor; a fluctuation amount derivation process, which derives an amount of fluctuation from a reference value of the moving speed acquired in the speed acquisition process; a determination process, which determines a target value of the moving speed based on the amount of fluctuation derived in the fluctuation amount derivation process; and a recording process, which ejects liquid from the nozzle toward a recording medium in the constant speed region while moving the head in the scanning direction by the moving mechanism so that the moving speed in the constant speed region becomes the target value determined in the determination process.

[0008] A control method according to the present invention is a control method for controlling a liquid ejection device including a head having nozzles formed therein, a transport mechanism that transports a recording medium in a transport direction, a movement mechanism that moves the head in a scanning direction perpendicular to the transport direction, a speed sensor that detects the movement speed of the head, and a control unit, wherein a movable region in which the head can be moved by the movement mechanism includes an acceleration region in which the head is accelerated, a deceleration region in which the head is decelerated, and a constant speed region that is between the acceleration region and the deceleration region in the scanning direction and in which the head is not accelerated or decelerated, the moving mechanism moves the head in the scanning direction and acquires the moving speed in the constant speed region from the speed sensor; a fluctuation amount derivation process derives an amount of variation from a reference value of the moving speed acquired in the speed acquisition process; a determination process determines a target value of the moving speed based on the amount of variation derived in the fluctuation amount derivation process; and a recording process ejects liquid from the nozzles towards a recording medium in the constant speed region while moving the head in the scanning direction by the moving mechanism such that the moving speed in the constant speed region becomes the target value determined in the determination process.

[0009] The program according to the present invention is a liquid ejection device including a head having nozzles formed therein, a transport mechanism that transports a recording medium in a transport direction, a movement mechanism that moves the head in a scanning direction perpendicular to the transport direction, and a speed sensor that detects the movement speed of the head, wherein a movable region in which the head can be moved by the movement mechanism includes an acceleration region in which the head is accelerated, a deceleration region in which the head is decelerated, and a constant speed region that is between the acceleration region and the deceleration region in the scanning direction and in which the head is not accelerated or decelerated, the liquid ejection device being configured to move the head in the scanning direction by the movement mechanism and detect the speed sensor. a speed acquisition means for acquiring the moving speed in the constant speed region from a sensor; a fluctuation amount derivation means for deriving an amount of variation from a reference value of the moving speed acquired by the speed acquisition means; a determination means for determining a target value of the moving speed based on the amount of variation derived by the fluctuation amount derivation means; and a recording means for ejecting liquid from the nozzles towards a recording medium in the constant speed region while moving the head in the scanning direction by the moving mechanism so that the moving speed in the constant speed region becomes the target value determined by the determination means. Effect of the Invention

[0010] According to the present invention, before the recording process, the actual head movement speed is acquired, the amount of variation of the acquired movement speed from a reference value is derived, and the target value of the movement speed is determined based on the amount of variation. In this way, by determining the target value based on the actual amount of variation rather than a predetermined amount of variation, it is possible to achieve both suppression of missing dots and high-speed recording without setting the target value too low. [Brief description of the drawings]

[0011] [Figure 1] 1 is a plan view showing a printer according to a first embodiment of the present invention. [Diagram 2] 3 is a cross-sectional view of a head included in the printer. [Diagram 3] FIG. 2 is a block diagram showing the electrical configuration of the printer. [Figure 4]11 is a graph showing changes in moving speed in the movable region of the head. [Diagram 5] 11 is a waveform diagram showing four types of waveform data included in waveform signal FIRE. FIG. [Figure 6] 10 is an explanatory diagram showing a process in which a waveform signal FIRE and a selection signal SIN are transferred from a transfer circuit to a driver IC. [Figure 7] 4 is a flow chart showing a program executed by the CPU of the printer. [Figure 8] 11 is a graph showing a situation in which a transport operation and a scanning operation are performed alternately. [Figure 9] FIG. 11 is a plan view showing a printer according to a second embodiment of the present invention. [Figure 10] 5 is a graph corresponding to FIG. 4 and illustrating the execution of the derivation of the amount of fluctuation for each unit area obtained by dividing the constant velocity area in the third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] First Embodiment As shown in FIG. 1, a printer 100 according to a first embodiment of the present invention comprises a head 10 having a plurality of nozzles N formed on its underside, a carriage 20 that holds the head 10, a moving mechanism 30 that moves the carriage 20 in a scanning direction (a direction perpendicular to the vertical direction), a platen 40 that supports paper P from below, a transport mechanism 50 that transports paper P in a transport direction (a direction perpendicular to the scanning direction and the vertical direction), and a control device 90.

[0013] The movement mechanism 30 includes a pair of guides 31, 32 that support the carriage 20, and a belt 33 connected to the carriage 20. The guides 31, 32 and the belt 33 extend in the scanning direction. When a carriage motor 30m (see FIG. 3) is driven under the control of the control device 90, the belt 33 runs, and the carriage 20 moves along the guides 31, 32 in the scanning direction.

[0014] The platen 40 is disposed below the carriage 20 and the head 10. A paper sheet P is placed on the upper surface of the platen 40.

[0015] The transport mechanism 50 has two roller pairs 51 and 52. The head 10, the carriage 20, and the platen 40 are disposed between the roller pairs 51 and 52 in the transport direction. When the transport motor 50m (see FIG. 3) is driven under the control of the control device 90, the roller pairs 51 and 52 rotate while holding the paper P therebetween, and the paper P is transported in the transport direction.

[0016] As shown in FIG. 2, the head 10 includes a flow path unit 12 and an actuator unit 13.

[0017] A plurality of nozzles N (see FIG. 1) are formed on the lower surface of the flow path unit 12. A plurality of pressure chambers 12p are formed on the upper surface of the flow path unit 12. A common flow path 12a communicating with an ink tank (not shown) and individual flow paths 12b for each nozzle N are formed inside the flow path unit 12. The individual flow paths 12b are flow paths that extend from the outlet of the common flow path 12a to the nozzles N via the pressure chambers 12p.

[0018] The actuator unit 13 includes a metallic vibration plate 13a arranged on the upper surface of the flow path unit 12 so as to cover the multiple pressure chambers 12p, a piezoelectric layer 13b arranged on the upper surface of the vibration plate 13a, and a plurality of individual electrodes 13c arranged on the upper surface of the piezoelectric layer 13b so as to face each of the multiple pressure chambers 12p.

[0019] The vibration plate 13a and the individual electrodes 13c are electrically connected to a driver IC 14. The driver IC 14 maintains the potential of the vibration plate 13a at the ground potential, while changing the potential of the individual electrodes 13c. Specifically, the driver IC 14 generates a drive signal based on a control signal (such as a waveform signal FIRE, a selection signal SIN, and a clock signal CLK, which will be described later) from the control device 90, and supplies the drive signal to the individual electrodes 13c via a signal line 14s for each ejection period (the period during which ink is ejected from the nozzle N). As a result, the potential of the individual electrodes 13c changes between a predetermined drive potential and a ground potential. At this time, the portions (actuators 13x) of the vibration plate 13a and the piezoelectric layer 13b sandwiched between each individual electrode 13c and each pressure chamber 12p are deformed, so that the volume of the pressure chamber 12p changes, pressure is applied to the ink in the pressure chamber 12p, and ink is ejected from the nozzle N. The actuator 13x is provided for each individual electrode 13c (that is, for each nozzle N), and is capable of independently deforming in response to the potential supplied to the individual electrode 13c.

[0020] As shown in Fig. 3, the control device 90 includes a CPU (Central Processing Unit) 91, a ROM (Read Only Memory) 92, a RAM (Random Access Memory) 93, and an ASIC (Application Specific Integrated Circuit) 94. The ROM 92 stores programs and data for the CPU 91 and the ASIC 94 to perform various controls. The RAM 93 temporarily stores data used when the CPU 91 and the ASIC 94 execute programs. The control device 90 is communicably connected to an external device (such as a personal computer), and executes recording processing and the like using the CPU 91 and the ASIC 94 based on data input from the external device or an input unit (a switch or button provided on the outer surface of the housing of the printer 100).

[0021] Here, the CPU 91 corresponds to the "control unit" of the present invention, and the RAM 93 corresponds to the "storage unit" of the present invention. The data stored in the RAM 93 includes the number of times the recording process has been executed (the recording process for one sheet of paper P is counted as one time).

[0022] In the recording process, the control device 90 controls the driver IC 14, the carriage motor 30m, and the transport motor 50m based on a recording command received from an external device, and alternately performs a transport operation in which the transport mechanism 50 transports the paper P a predetermined amount in the transport direction, and a scanning operation in which the movement mechanism 30 moves the carriage 20 in the scanning direction while ejecting ink from the nozzles N. In the scanning operation, the control device 90 causes the driver IC 14 to supply a drive signal to the individual electrodes 13c, thereby ejecting ink from the nozzles N. In this way, ink dots are formed on the paper P, and an image is recorded.

[0023] The movement of the head 10 in the scanning direction includes an outward movement to the right in FIG. 1, and a return movement to the left in FIG. 1. In each of the outward movement and the return movement, the movable region of the head 10 (the region from the start point to the end point of each movement) includes an acceleration region where the head 10 is accelerated, a deceleration region where the head 10 is decelerated, and a constant speed region between the acceleration region and the deceleration region in the scanning direction where the head 10 is not accelerated or decelerated, as shown in FIG. 4. In the constant speed region, ink is ejected. Here, the movement speed of the head 10 in the constant speed region is controlled to a constant target value Vt, but a variation from the target value Vt occurs due to product variations in the movement mechanism 30, environmental temperature, environmental humidity, etc. (see the dashed line in FIG. 4). Problems based on this variation will be described in detail later.

[0024] Next, the configuration of the ASIC 94 will be described.

[0025] As shown in FIG. 3, the ASIC 94 includes an output circuit 941 and a transfer circuit 942 .

[0026] The output circuit 941 generates a waveform signal FIRE, a selection signal SIN, a clock signal CLK, and the like, and outputs these signals to a transfer circuit 942 for each ejection period.

[0027] The waveform signal FIRE is a serial signal obtained by serializing four waveform data F0 to F3 (see FIG. 5) that respectively indicate four driving modes of the actuator 13x. The waveform data F0 (see FIG. 5(a)) corresponds to the amount of ink discharged from the nozzle N in one discharge cycle being "zero (no discharge)", and maintains the potential of the individual electrode 13c at the ground potential (0V). The waveform data F1 (see FIG. 5(b)) corresponds to the amount of ink discharged from the nozzle N in one discharge cycle being "small", and includes one pulse that changes the potential of the individual electrode 13c between the ground potential (0V) and the drive potential (VDD), and causes one drop of ink to be discharged. The waveform data F2 (see FIG. 5(c)) corresponds to the amount of ink discharged from the nozzle N in one discharge cycle being "medium", and includes two pulses that change the potential of the individual electrode 13c between the ground potential (0V) and the drive potential (VDD), and causes two drops of ink to be discharged. Waveform data F3 (see Figure 5 (d)) corresponds to a "large" amount of ink ejected from nozzle N within one ejection cycle, and includes four pulses that change the potential of individual electrode 13c between the ground potential (0V) and the drive potential (VDD), ejecting four drops of ink.

[0028] The waveform signal FIRE includes the above four waveform data F0 to F3 (see FIG. 5), and as a whole indicates four drive modes of the actuator 13x.

[0029] The driving mode of the actuator 13x refers to the above-mentioned deformation mode of the actuator 13x in response to the change in the potential of the individual electrode 13c. The driving mode of the actuator 13x differs in response to the change in the potential of the individual electrode 13c (i.e., for each of the waveform data F0 to F3). The change in the volume of the pressure chamber 12p, the state of the meniscus formed in the nozzle N, and the amount of ink ejected from the nozzle N (including zero) differ depending on the driving mode.

[0030] The selection signal SIN is a serial signal including selection data for selecting one of the above four driving modes, and is generated for each actuator 13x and for each ejection period based on image data included in the recording command. The ejection period is determined according to the amount of change in the relative position between the head 10 and the paper P per unit time, and becomes shorter as the amount of change increases (specifically, as the moving speed of the head 10 increases).

[0031] The clock signal CLK indicates the transfer timing of various signals from the ASIC 94 to the driver IC 14. The clock signal CLK is generated and output based on image data included in the recording command, a signal from a rotary encoder 61 provided on the carriage motor 30m, and a signal from a paper sensor 62 provided on the transport path of the paper P. The rotary encoder 61 detects the moving speed of the head 10, and corresponds to the "speed sensor" of the present invention.

[0032] The transfer circuit 942 transfers the waveform signal FIRE, the selection signal SIN, the clock signal CLK, etc. received from the output circuit 941 to the driver IC 14 in synchronization with the clock signal CLK (at the transfer timing indicated by the clock signal CLK) for each ejection period. The transfer circuit 942 has built-in LVDS (Low Voltage Differential Signaling) drivers corresponding to each of the above signals, and transfers each signal to the driver IC 14 as a pulse-shaped differential signal. The LVDS method is a method in which signals of opposite phases (H signal and L signal) are input to two signal lines, and is characterized by being resistant to noise and capable of transmitting at a low voltage by reducing the amplitude of the signal compared to a single-ended method in which a signal is input using only one signal line. The LVDS method can reduce the amplitude of the signal, so that the time required for switching between the H signal and the L signal can be shortened, and as a result, the frequency of the signal can be increased and data can be transmitted at a high speed. In particular, the selection signal SIN includes selection data for the number of actuators 13x (the number of nozzles N), so the amount of data can be enormous. By transferring this signal using the LVDS method, high-speed transmission is possible.

[0033] Next, the transfer of waveform signal FIRE and selection signal SIN from transfer circuit 942 to driver IC 14 will be described.

[0034] 6(a) and 6(b), time points t1 to t3 are the times when the transfer of waveform signal FIRE and selection signal SIN should start. The time between chronologically adjacent times t1 to t3 corresponds to an ejection period, with time point t1 being the start of the first ejection period, time point t2 being the start of the second ejection period, and time point t3 being the start of the first ejection period.

[0035] In each ejection cycle, the transfer of the selection signal SIN ends after the transfer of the waveform signal FIRE ends, and the selection signal SIN is latched at the end of the transfer of the selection signal SIN.

[0036] Typically, as shown in FIG. 6(a), after the transfer of the waveform signal FIRE and the selection signal SIN for one ejection cycle is completed, the transfer timing for the next ejection cycle occurs and the transfer of the waveform signal FIRE and the selection signal SIN begins.

[0037] However, for example, when the moving speed of the head 10 increases or the amount of variation from the target value Vt of the moving speed of the head 10 in the constant speed region (the difference between the target value Vt and the maximum value Vmax shown in FIG. 4) increases, unlike the normal time described above, a transfer timing (time t2) for the second ejection cycle occurs during the transfer of the waveform signal FIRE and selection signal SIN for the first ejection cycle, as shown in FIG. 6(b). In this case, the transfer circuit 942 cannot normally capture the waveform signal FIRE and selection signal SIN for the second ejection cycle, and as a result, the waveform signal FIRE and selection signal SIN for the second ejection cycle cannot be transferred to the driver IC 14. This results in non-ejection in the second ejection cycle, which can cause missing dots.

[0038] In order to suppress missing dots, it is conceivable to determine a target value Vt (see FIG. 4) of the moving speed of the head 10 in the constant speed region so that the signal transfer for each ejection cycle is completed even when the moving speed is at its maximum value Vmax for a predetermined amount of fluctuation (e.g., ±5%). However, the amount of fluctuation is due to product variations, etc., and if the actual amount of fluctuation is smaller than the predetermined amount of fluctuation (e.g., ±2%), the signal transfer can be completed even if the target value Vt is set higher than the target value based on the predetermined amount of fluctuation (e.g., ±5%). In other words, if the target value Vt is determined based on a predetermined amount of fluctuation (e.g., ±5%), the target value Vt will be set too low, which may hinder high-speed recording.

[0039] Therefore, in this embodiment, in order to achieve both suppression of missing dots and high-speed recording, the CPU 91 executes the processes of S2 to S4 when the printer 100 is manufactured (before shipping), after a predetermined time has elapsed after the printer 100 is manufactured, and when the number of times X that the recording process has been executed exceeds a predetermined number Xt, as shown in FIG. 7.

[0040] In FIG. 7, the CPU 91 first determines whether or not the number of times X that the recording process has been performed has exceeded a predetermined number of times Xt, based on information obtained from the RAM 93 (S1).

[0041] When the number of execution times X of the recording process does not exceed the predetermined number of execution times Xt (S1: NO), the CPU 91 repeats the process of S1.

[0042] If the number of times X that the recording process has been executed exceeds a predetermined number of times Xt (S1: YES), the CPU 91 moves the head 10 in the scanning direction using the moving mechanism 30, and acquires the head 10 moving speed in the constant speed region based on the signal from the rotary encoder 61 (S2: speed acquisition process).

[0043] After S2, the CPU 91 derives the amount of variation from a reference value of the moving speed acquired in S2 (S3: variation amount derivation process). The reference value is a predetermined speed stored in the ROM 92.

[0044] For example, in S2, the CPU 91 causes the head 10 to perform a reciprocating movement consisting of a forward movement (movement to the right in Figure 1) and a return movement (movement to the left in Figure 1) a total of about six times, and acquires the movement speed of the head 10 in the constant speed region for each movement in chronological order, and in S3, derives the maximum amount of variation from a reference value of the movement speed of the head 10 in the constant speed region for each movement.

[0045] After S3, the CPU 91 determines a target value Vt of the moving speed based on the amount of fluctuation derived in S3 (S4: determination process).

[0046] After S4, the CPU 91 ends the program.

[0047] The target value Vt determined in S4 is stored in the RAM 93 until the next time the processes of S2 to S4 are executed. In the recording process, the CPU 91 ejects ink from the nozzles N toward the paper P in the constant speed region while moving the head 10 in the scanning direction by the movement mechanism 30 so that the movement speed in the constant speed region becomes the target value Vt determined in S4.

[0048] In addition, when the head 10 moves to eject ink, the CPU 91 controls the moving mechanism 30 so that the moving speed in the constant speed region becomes the target value Vt determined in S4. However, in other cases (when the head is moved in a manner that does not eject ink (for example, when moving back in one-way recording in which ink is ejected in the forward movement but not in the return movement), when detecting the width of the paper P, or when performing a maintenance operation at a maintenance position at the end point of the movement to prevent the nozzle N from drying out, the CPU 91 may control the moving mechanism 30 so that the moving speed in the constant speed region becomes a target value other than the target value Vt determined in S4.

[0049] Depending on the moving speed of the head 10, the flying direction of the ink ejected from the nozzle N changes, and the landing position of the ink on the paper P also changes. Therefore, the CPU 91 adjusts the ejection timing of the ink from the nozzle N in the constant speed region (the transfer timing of various signals from the ASIC 94 to the driver IC 14) based on the target value Vt determined in S4. For example, the higher the target value Vt, the earlier the ejection timing is set than the predetermined ejection timing determined based on the image data. A table (a table showing the relationship between the moving speed of the head 10 and the adjustment value of the ejection timing) is stored in the ROM 92, and the CPU 91 adjusts the ejection timing by referring to the table. Alternatively, a derivation formula (a derivation formula for deriving an adjustment value of the ejection timing from the moving speed of the head 10) may be stored in the ROM 92, and the CPU 91 may adjust the ejection timing based on the derivation formula.

[0050] The length of the acceleration region and the deceleration region changes according to the moving speed of the head 10 in the constant speed region (specifically, the higher the moving speed of the head 10 in the constant speed region, the longer the length of the acceleration region and the deceleration region), and the time from the start of the movement of the head 10 in one scanning operation to the time when the head 10 reaches the constant speed region changes. Therefore, the CPU 91 adjusts the timing of the transport operation based on the target value Vt determined in S4 (see FIG. 8). In FIG. 8, the solid line indicates the moving speed of the head 10 in the scanning operation, and the dashed line indicates the transport speed of the paper P in the transport operation. In the example of FIG. 8, the movement of the head 10 in the scanning operation and the transport operation partially overlap. Specifically, in each scanning operation, the transport operation is started at the end of the ejection of ink in the constant speed region before the end of the movement of the head 10 (the time when the head 10 reaches the end point shown in FIG. 4). Also, the movement of the head 10 in the scanning operation starts before the end of the transport operation, and the ejection of ink in the constant speed region starts at the end of the transport operation. Ink ejection in the constant speed region and the transport operation do not overlap.

[0051] As described above, according to this embodiment, before the recording process, the actual moving speed of the head 10 is acquired (S2), the amount of variation of the acquired moving speed from a reference value is derived (S3), and the target value Vt of the moving speed is determined based on the amount of variation (S4). In this way, by determining the target value Vt based on the actual amount of variation rather than a predetermined amount of variation, it is possible to achieve both suppression of missing dots and high-speed recording without making the target value Vt excessively low.

[0052] As described above, the ink flight direction and the ink landing position change according to the moving speed of the head 10, so the CPU 91 adjusts the ejection timing based on the moving speed target value Vt, thereby making it possible to set the ink landing position to a desired position and maintain recording quality.

[0053] Furthermore, as described above, the length of the acceleration region and the deceleration region changes according to the moving speed of the head 10 in the constant speed region (specifically, the faster the moving speed of the head 10 in the constant speed region, the longer the length of the acceleration region and the deceleration region), and in consideration of the change in the time from the start of the movement of the head 10 in one scanning operation to the time when the head 10 reaches the constant speed region, the CPU 91 adjusts the timing of the transport operation based on the target value Vt determined in S4 (see FIG. 8). Then, by partially overlapping the movement of the head 10 in the scanning operation and the transport operation as shown in FIG. 8, or by starting the transport operation at the end of the movement of the head 10 in the scanning operation, high-speed recording can be realized.

[0054] The CPU 91 executes S2 to S4 when the number of executions X of the recording process exceeds a predetermined number of times Xt (S1: YES). This is in consideration of the fact that the performance of the movement mechanism 30 and the like may change as the number of executions of the recording process increases (and thus the amount of fluctuation in the movement speed of the head 10 may change). When the number of executions X of the recording process exceeds the predetermined number of times Xt, S2 to S4 are executed and the target value Vt is updated, thereby achieving recording suited to the current situation.

[0055] <Second embodiment> A printer 200 (see FIG. 9) according to a second embodiment of the present invention differs from the printer 100 (see FIG. 1) according to the first embodiment in that the transport mechanism 50 includes a corrugated shape imparting section 510 and that the ejection timing is adjusted based not only on the target value Vt of the moving speed but also on the corrugated shape imparted to the paper P by the corrugated shape imparting section 510.

[0056] The corrugated shape imparting section 510 imparts a corrugated shape along the scanning direction to the paper P, and includes five corrugated plates 511, four ribs 512, and spur rollers 513 and 514.

[0057] The five corrugated plates 511 are disposed at equal intervals in the scanning direction. Each corrugated plate 511 includes a base portion that covers the upper roller of the roller pair 51 on the upstream side in the transport direction relative to the head 10, and a pressing portion that extends from the base portion to the downstream side in the transport direction. A small gap is provided between the pressing portion and the surface of the platen 40.

[0058] The four ribs 512 each extend in the transport direction between two corrugated plates 511 adjacent in the scanning direction. The upper end of each rib 512 is located above the pressing portion of each corrugated plate 511. In this positional relationship, the upper end of each rib 512 supports the paper P from below, and the pressing portions of each corrugated plate 511 press the paper P from above, thereby imparting a corrugated shape along the scanning direction to the paper P.

[0059] The spur rollers 513 and 514 constitute the upper rollers of the roller pair 52 downstream in the transport direction relative to the head 10. The spur roller 513 is positioned so as to overlap with each of the four ribs 512 in the transport direction. The spur roller 514 is positioned so as to overlap with each of the five corrugated plates 511 in the transport direction. The contact point between the spur roller 513 and the lower roller (not shown) of the roller pair 52 is above the lower end of the spur roller 514. In this positional relationship, the lower roller of the roller pair 52 supports the paper P from below, and the spur roller 514 presses the paper P from above, giving the paper P a corrugated shape along the scanning direction.

[0060] The corrugated shape imparting section 510 imparts a corrugated shape to the paper P along the scanning direction, so that the paper P is given stiffness and good transport is achieved.

[0061] However, in order to maintain the recording quality when a corrugated shape is applied to the paper P, it is necessary to change the ejection timing of ink from the nozzles N from the ejection timing when a corrugated shape is not applied to the paper P. Therefore, in this embodiment, the ejection timing is adjusted based on not only the target value Vt of the moving speed but also the corrugated shape applied by the corrugated shape applying unit 510.

[0062] According to this embodiment, in addition to the effects of the first embodiment, when a corrugated shape is imparted to the paper P, the ink landing position can be set to the desired position by appropriately setting the ejection timing, thereby maintaining recording quality.

[0063] <Third embodiment> The third embodiment of the present invention (see FIG. 10) differs from the first embodiment (see FIG. 4) in that the CPU 91 executes the processes of S2 to S4 for each of three unit areas (first to third unit areas) aligned in the scanning direction in the constant speed area.

[0064] Specifically, the CPU 91 acquires the moving speed of the head 10 for each unit area in S2, derives the amount of fluctuation for each unit area in S3, and determines the target value Vt for each unit area based on the amount of fluctuation for each unit area derived in S3 in S4. If the amount of fluctuation differs for each unit area, the target value Vt will also differ.

[0065] According to this embodiment, by executing the processes of S2 to S4 for each unit area, it is possible to set the target value Vt higher in a certain unit area than in other unit areas. Therefore, when the range in which ink is ejected in the constant speed area corresponds to the certain unit area, high speed recording can be achieved.

[0066] <Modification> Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and various design modifications are possible within the scope of the claims.

[0067] In the embodiment described above (see FIG. 8), the movement of the head in the scanning operation and the transport operation partially overlap, but this is not limited to this. For example, the transport operation may be started at the end of the movement of the head in the scanning operation, or the movement of the head in the scanning operation may be started at the end of the transport operation.

[0068] In the third embodiment (see FIG. 10), the moving speed of the head 10 for each unit area is acquired in S2, the amount of fluctuation for each unit area is derived in S3, and the target value Vt for each unit area is determined based on the amount of fluctuation for each unit area derived in S3 in S4, but this is not limiting. For example, the target value Vt for the constant speed area (including all unit areas) may be determined based on the maximum amount of fluctuation among the amounts of fluctuation for each unit area derived in S3 in S4.

[0069] When one-way printing is performed, the target value Vt may be determined only for the forward movement. For example, the speed of the backward movement may not be acquired in S2, the fluctuation amount of only the forward movement may be derived in S3, and the target value Vt of the forward movement may be determined in S4 based on the fluctuation amount of the forward movement derived in S3.

[0070] The actuator is not limited to a piezoelectric type, and may be of another type (for example, a thermal type using a heating element, an electrostatic type using electrostatic force, etc.).

[0071] The liquid ejected from the nozzles is not limited to ink, and may be a liquid other than ink (for example, a treatment liquid that aggregates or precipitates components in the ink, etc.).

[0072] The present invention is not limited to printers, but can also be applied to facsimiles, copy machines, multifunction machines, etc. The present invention can also be applied to liquid ejection devices used for purposes other than image recording (for example, liquid ejection devices that eject conductive liquid onto a substrate to form a conductive pattern).

[0073] The program according to the present invention can be distributed by recording it on a removable recording medium such as a flexible disk or a fixed recording medium such as a hard disk, or can be distributed via a communication line. [Explanation of symbols]

[0074] 100;200 Printer (liquid ejection device) 10 Head 30 Moving mechanism 50 Conveyor mechanism 61 Rotary encoder (speed sensor) 91 CPU (control unit) 93 RAM (memory section) N Nozzle P Paper (recording medium)

Claims

1. A head having a nozzle formed therein; a conveying mechanism that conveys the recording medium in a conveying direction; a moving mechanism that moves the head in a scanning direction perpendicular to the transport direction; a speed sensor that detects the moving speed of the head; A control unit, a movable region in which the head can be moved by the moving mechanism includes an acceleration region in which the head is accelerated, a deceleration region in which the head is decelerated, and a constant speed region located between the acceleration region and the deceleration region in the scanning direction and in which the head is not accelerated or decelerated, The control unit is a speed acquisition process of moving the head in the scanning direction by the moving mechanism and acquiring the moving speed in the constant speed region from the speed sensor; a fluctuation amount derivation process for deriving a maximum fluctuation amount from a reference value of the movement speed acquired in the speed acquisition process; a determination process of determining a target value of the moving speed based on the maximum fluctuation amount derived in the fluctuation amount derivation process; a recording process for ejecting liquid from the nozzles toward a recording medium in the constant speed region while moving the head in the scanning direction by the movement mechanism so that the movement speed in the constant speed region becomes the target value determined in the determination process; and A liquid ejection apparatus comprising:

2. The control unit is The liquid ejection device according to claim 1 , further comprising: a step of adjusting a timing for ejecting liquid from said nozzle in said constant velocity region based on said target value determined in said determination process.

3. The control unit is In the recording process, a conveying operation in which the conveying mechanism conveys the recording medium a predetermined amount in the conveying direction and a scanning operation in which the moving mechanism moves the head in the scanning direction while discharging liquid from the nozzles toward the recording medium are alternately performed; 3. The liquid ejection apparatus according to claim 1, wherein the timing of the transport operation is adjusted based on the target value determined in the determination process.

4. A storage unit that stores the number of times the recording process is performed, The control unit is A liquid ejection device according to any one of claims 1 to 3, characterized in that the speed acquisition process, the fluctuation amount derivation process, and the determination process are executed when the number of executions stored in the memory unit exceeds a predetermined number of times.

5. The control unit is 5. The liquid ejection device according to claim 1, wherein the variation amount derivation process, the determination process, and the recording process are performed for each of a plurality of unit areas aligned in the scanning direction in the constant speed area.

6. A control method for controlling a liquid ejection device including a head having nozzles formed therein, a transport mechanism for transporting a recording medium in a transport direction, a movement mechanism for moving the head in a scanning direction perpendicular to the transport direction, a speed sensor for detecting a moving speed of the head, and a control unit, the method comprising the steps of: a movable region in which the head can be moved by the moving mechanism includes an acceleration region in which the head is accelerated, a deceleration region in which the head is decelerated, and a constant speed region located between the acceleration region and the deceleration region in the scanning direction and in which the head is not accelerated or decelerated, a speed acquisition process of moving the head in the scanning direction by the moving mechanism and acquiring the moving speed in the constant speed region from the speed sensor; a fluctuation amount derivation process for deriving a maximum fluctuation amount from a reference value of the movement speed acquired in the speed acquisition process; a determination process of determining a target value of the moving speed based on the maximum fluctuation amount derived in the fluctuation amount derivation process; a recording process for ejecting liquid from the nozzles toward a recording medium in the constant speed region while moving the head in the scanning direction by the movement mechanism so that the movement speed in the constant speed region becomes the target value determined in the determination process; and A control method comprising:

7. a liquid ejection device comprising a head having nozzles formed therein, a transport mechanism for transporting a recording medium in a transport direction, a movement mechanism for moving the head in a scanning direction perpendicular to the transport direction, and a speed sensor for detecting the movement speed of the head, wherein a movable region in which the head can be moved by the movement mechanism includes an acceleration region in which the head is accelerated, a deceleration region in which the head is decelerated, and a constant speed region between the acceleration region and the deceleration region in the scanning direction in which the head is not accelerated or decelerated, a speed acquisition means for moving the head in the scanning direction by the moving mechanism and acquiring the moving speed in the constant speed region from the speed sensor; a fluctuation amount deriving means for deriving a maximum fluctuation amount of the movement speed acquired by the speed acquisition means from a reference value; a determination means for determining a target value of the moving speed based on the maximum fluctuation amount derived by the fluctuation amount derivation means; and a recording means for ejecting liquid from the nozzles towards a recording medium in the constant speed region while moving the head in the scanning direction by the moving mechanism so that the moving speed in the constant speed region becomes the target value determined by the determining means; The program is characterized by causing the program to function as follows.

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