Ink jet printer, carriage speed measuring method and ink jet printer control method

Abstract

To provide an ink jet printer comprising an ink jet head, a carriage on which the ink head jet head is mounted, and a carriage drive mechanism for moving the carriage in a main scanning direction, which can ensure printing accuracy even if a speed of the carriage reciprocating in the main scanning direction varies while reducing costs.SOLUTION: In this ink jet printer, speed variation data, which is generated by previously measuring speed variation at each resolution of a carriage reciprocating in a main scanning direction during printing, is stored in a control part 7, and printing data for performing printing is inputted to the same before printing. The control part 7 generates a trigger signal for discharging an ink from an ink jet head on the basis of the printing data and the speed variation data during printing, and discharges the ink from the ink jet head.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inkjet printer that prints by ejecting ink, a carriage speed measurement method for measuring carriage speed fluctuations at each resolution in such an inkjet printer, and a control method for an inkjet printer that prints by ejecting ink. [Background technology]

[0002] Conventionally, inkjet printers that print on media are known (see, for example, Patent Document 1). The inkjet printer described in Patent Document 1 includes a printer head that ejects ink, a carriage on which the printer head is mounted, a Y-bar that movably supports the carriage, a carriage drive device that moves the carriage in the main scanning direction, a linear encoder that detects the position of the carriage in the main scanning direction, and an ejection control unit that controls piezoelectric elements and the like of the printer head.

[0003] In the inkjet printer described in Patent Document 1, the carriage drive device includes a conveyor belt connected to the carriage and a drive motor that drives the conveyor belt. The carriage drive device changes the carriage movement speed depending on, for example, the resolution of the image to be printed on the medium. The linear encoder includes a linear scale installed parallel to the Y bar and a sensor for reading reference marks formed on the linear scale. The sensor is mounted on the carriage. The ejection control unit generates a trigger signal for ejecting ink from the print head based on the output signal of the linear encoder sensor, thereby ejecting ink from the printer head.

[0004] In the inkjet printer described in Patent Document 1, even if the carriage is moved at a completely constant speed in the main scanning direction when printing on a medium, the carriage movement speed fluctuates due to the structure of the inkjet printer. However, in this inkjet printer, the ejection control unit generates a trigger signal based on the output signal of the linear encoder sensor to eject ink from the printer head, so even if the speed of the carriage reciprocating in the main scanning direction fluctuates, it is possible to land ink on the media with high precision, making it possible to print on the media with high precision. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-74149 Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors of the present application are developing an inkjet printer that includes an inkjet head that ejects ink, a carriage on which the inkjet head is mounted, and a carriage drive mechanism that moves the carriage in the main scanning direction, similar to the inkjet printer described in Patent Document 1. It is preferable that this inkjet printer under development ensures printing accuracy even if the speed of the carriage that reciprocates in the main scanning direction fluctuates, similar to the inkjet printer described in Patent Document 1. It is also preferable that this inkjet printer under development be less expensive.

[0007] Therefore, an object of the present invention is to provide an inkjet printer that includes an inkjet head, a carriage on which the inkjet head is mounted, and a carriage drive mechanism that moves the carriage in the main scanning direction, and that can reduce costs while ensuring printing accuracy even if the speed of the carriage that moves back and forth in the main scanning direction varies.Another object of the present invention is to provide a carriage speed measurement method for measuring carriage speed fluctuations at each resolution in such an inkjet printer.

[0008] Furthermore, an object of the present invention is to provide a control method for an inkjet printer that includes an inkjet head, a carriage on which the inkjet head is mounted, and a carriage drive mechanism that moves the carriage in the main scanning direction, which can reduce the cost of the inkjet printer while ensuring printing accuracy even if the speed of the carriage that moves back and forth in the main scanning direction varies. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the inventors of the present invention conducted various studies. As a result, the inventors discovered that although there are individual differences in the speed fluctuation of a carriage reciprocating in the main scanning direction among inkjet printers, the carriage speed fluctuates in approximately the same manner in a single inkjet printer even when the carriage is repeatedly reciprocated in the main scanning direction. Based on this discovery, the inventors discovered that by measuring the speed fluctuation of the carriage reciprocating at each resolution for each inkjet printer in advance, generating and storing speed fluctuation data based on the speed fluctuation measurement results, and ejecting ink from the inkjet head based on this speed fluctuation data during printing, it is possible to ensure printing accuracy even if the inkjet printer does not have a linear encoder for detecting the position of the carriage in the main scanning direction and even if the speed of the carriage reciprocating in the main scanning direction fluctuates.

[0010] The inkjet printer of the present invention is based on this new finding, and is an inkjet printer that prints by ejecting ink, comprising an inkjet head that ejects ink, a carriage on which the inkjet head is mounted, a carriage drive mechanism that moves the carriage in the main scanning direction, and a control unit for controlling the inkjet printer, wherein the control unit stores speed fluctuation data that is generated by measuring in advance the speed fluctuation at each resolution of the carriage that moves back and forth in the main scanning direction during printing, and print data for printing is input before printing, and during printing the control unit generates a trigger signal for ejecting ink from the inkjet head based on the print data and the speed fluctuation data, and causes ink to be ejected from the inkjet head.

[0011] Furthermore, based on the above-mentioned new findings, the control method for an inkjet printer of the present invention is a control method for an inkjet printer that includes an inkjet head that ejects ink, a carriage on which the inkjet head is mounted, and a carriage drive mechanism that moves the carriage in a main scanning direction, and is characterized in that speed fluctuation data that is generated by measuring in advance the speed fluctuation at each resolution of the carriage that moves back and forth in the main scanning direction during printing is stored, and during printing, a trigger signal for ejecting ink from the inkjet head is generated based on the print data for printing and the speed fluctuation data, and ink is ejected from the inkjet head.

[0012] In this invention, speed fluctuation data generated by measuring in advance the speed fluctuation of the carriage that reciprocates in the main scanning direction during printing at each resolution is stored, and during printing, a trigger signal for ejecting ink from the inkjet head is generated based on the print data and the speed fluctuation data, causing the ink to be ejected from the inkjet head. Therefore, this invention makes it possible to ensure printing accuracy even if the inkjet printer does not include a linear encoder for detecting the position of the carriage in the main scanning direction and even if the speed of the carriage that reciprocates in the main scanning direction fluctuates. Therefore, this invention makes it possible to ensure printing accuracy even if the speed of the carriage that reciprocates in the main scanning direction fluctuates, while reducing the cost of the inkjet printer.

[0013] In the present invention, for example, the carriage drive mechanism includes a motor, a power transmission mechanism for transmitting the power of the motor to the carriage, and a rotary encoder for detecting the rotational speed of the motor, and the speed fluctuation of the carriage at each resolution is measured using the rotary encoder, and the control unit generates a trigger signal based on a predetermined correction value, print data, and speed fluctuation data during printing.

[0014] According to the inventor's research, an inkjet printer is equipped with a linear encoder for detecting the carriage position in the main scanning direction, and it has been found that the carriage speed fluctuations at each resolution measured using this linear encoder are offset by a certain time from the carriage speed fluctuations at each resolution measured using a rotary encoder. Therefore, by having the control unit generate a trigger signal based on a predetermined correction value, print data, and speed fluctuation data during printing, it becomes possible to ensure printing accuracy even when the carriage speed fluctuations at each resolution are measured using a rotary encoder.

[0015] A carriage speed measurement method for measuring carriage speed fluctuations at each resolution in an inkjet printer of the present invention includes, for example, a linear encoder mounting step of attaching a linear scale to a carriage support member that movably supports the carriage and attaching a sensor to the carriage for detecting the linear scale; a speed measurement step of moving the carriage back and forth in the main scanning direction after the linear encoder mounting step and measuring the carriage speed at each resolution based on the detection results of the sensor; and a linear encoder removal step of removing the linear scale from the carriage support member and removing the sensor from the carriage after the speed measurement step.

[0016] Furthermore, the carriage speed measurement method for measuring carriage speed fluctuations at each resolution in an inkjet printer of the present invention includes, for example, a speed measurement step of reciprocating the carriage in the main scanning direction and measuring the carriage speed at each resolution based on the detection results of a rotary encoder. In this case, there is no need to attach or detach the linear scale and sensor when measuring carriage speed fluctuations. Therefore, it is possible to easily measure carriage speed fluctuations.

[0017] In the present invention, for example, the carriage speed fluctuation at each resolution is measured for each inkjet printer. [Effects of the Invention]

[0018] As described above, the present invention makes it possible for an inkjet printer equipped with an inkjet head, a carriage on which the inkjet head is mounted, and a carriage drive mechanism that moves the carriage in the main scanning direction to reduce the cost of the inkjet printer while ensuring printing accuracy even if the speed of the carriage that moves back and forth in the main scanning direction fluctuates. [Brief explanation of the drawings]

[0019] [Figure 1]1 is a schematic diagram illustrating a configuration of an inkjet printer according to an embodiment of the present invention. [Figure 2] FIG. 2 is a block diagram illustrating the configuration of the inkjet printer shown in FIG. [Figure 3] 2 is a schematic diagram for explaining the state of the inkjet printer when measuring the speed fluctuation of the carriage shown in FIG. 1. FIG. [Figure 4] 3 is a diagram for explaining a method of generating speed fluctuation data stored in the control unit shown in FIG. 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0021] (Outline of inkjet printer configuration) Fig. 1 is a schematic diagram illustrating the configuration of an inkjet printer 1 according to an embodiment of the present invention, and Fig. 2 is a block diagram illustrating the configuration of the inkjet printer 1 shown in Fig. 1.

[0022] The inkjet printer 1 (hereinafter referred to as "printer 1") of this embodiment is, for example, a commercial inkjet printer that ejects ink to print on a medium 2. The printer 1 includes an inkjet head 3 (hereinafter referred to as "head 3") that ejects ink toward the medium 2, a carriage 4 on which the head 3 is mounted, a Y bar 5 as a carriage support member that movably supports the carriage 4, a carriage drive mechanism 6 that moves the carriage 4 in a main scanning direction (Y direction in FIG. 1) that is perpendicular to the up-down direction (vertical direction), and a control unit 7 for controlling the printer 1. The printer 1 also includes a medium feed mechanism (not shown) that transports the medium 2 in a sub-scanning direction (X direction in FIG. 1) that is perpendicular to the up-down direction and the main scanning direction.

[0023] When the printer 1 prints on the medium 2, the carriage 4 moves back and forth in the main scanning direction and the medium 2 is fed in the sub-scanning direction alternately and repeatedly. The head 3 ejects ink when the carriage 4 moves back and forth in the main scanning direction. The printer 1 is capable of printing on the medium 2 at a plurality of resolutions. For example, the printer 1 is capable of printing on the medium 2 at 600 dpi (dots per inch), 800 dpi, or 1200 dpi.

[0024] The head 3 ejects ink downward. A platen 8 is disposed below the head 3. The medium 2 is placed on the platen 8 during printing. A plurality of nozzles (specifically, a large number of nozzles) that eject ink are formed on the underside of the head 3. The underside of the head 3 serves as an ink ejection surface. The head 3 is equipped with a plurality of piezoelectric elements (piezo elements) 9 that eject ink from each of the plurality of nozzles. The piezoelectric elements 9 are electrically connected to the control unit 7.

[0025] The carriage drive mechanism 6 moves the carriage 4 linearly relative to the Y bar 5. The movement speed of the carriage 4 varies depending on the resolution of the image to be printed on the medium 2. Specifically, the lower the resolution, the faster the movement speed of the carriage 4, and the higher the resolution, the slower the movement speed of the carriage 4. By design, the carriage drive mechanism 6 moves the carriage 4 in the main scanning direction at a constant speed without fluctuation for each resolution. However, in reality, due to the structure of the printer 1, the movement speed of the carriage 4 will fluctuate even if you try to move the carriage 4 at a completely constant speed when printing on the medium 2.

[0026] The carriage drive mechanism 6 includes a motor 11, a power transmission mechanism 12 for transmitting the power of the motor 11 to the carriage 4, and a rotary encoder 13 for detecting the rotation speed of the motor 11. The power transmission mechanism 12 includes a belt 14, a portion of which is fixed to the carriage 4. The power transmission mechanism 12 also includes a pulley 15 around which the belt 14 is stretched. The motor 11 is connected to the pulley 15, and rotates the pulley 15. The motor 11 is electrically connected to the control unit 7.

[0027] The rotary encoder 13 includes a rotary scale (not shown) attached to the rotor of the motor 11, and a sensor 16 for detecting the rotary scale. The rotary scale is formed in a disk shape. The rotary scale has, for example, a plurality of slit-shaped through holes that penetrate the rotary scale in the thickness direction of the rotary scale. The sensor 16 is, for example, a transmissive optical sensor. A portion of the rotary scale is disposed between the light-emitting portion and the light-receiving portion of the sensor 16. The sensor 16 is electrically connected to the control unit 7, and the output signal of the sensor 16 is input to the control unit 7. The output signal of the sensor 16 (i.e., the output signal of the rotary encoder 13) is a square-wave pulse signal.

[0028] The control unit 7 includes an ejection control unit 17 for controlling the piezoelectric element 9 to control the timing of ink ejection from the head 3. The ejection control unit 17 is, for example, an integrated circuit such as an FPGA (Field Programmable Gate Array). The piezoelectric element 9 and the sensor 16 are electrically connected to the ejection control unit 17. The control unit 7 also includes a ROM (Read Only Memory) 18 in which various data are stored.

[0029] A PC (Personal Computer) 19 is electrically connected to the control unit 7. The PC 19 generates print data for printing on the medium 2. When printing on the medium 2, the print data generated by the PC 19 is sent from the PC 19 to the control unit 7. In other words, the print data is input to the control unit 7 before printing on the medium 2. The print data includes data on the resolution of the image to be printed on the medium 2. The print data also includes data on the print range and print position in the main scanning direction.

[0030] The control unit 7 stores speed fluctuation data generated by previously measuring the speed fluctuation at each resolution of the carriage 4, which moves back and forth in the main scanning direction when printing on the medium 2. When printing on the medium 2, the control unit 7 generates a trigger signal for ejecting ink from the head 3 based on the print data and the speed fluctuation data, and causes the head 3 to eject ink. Specifically, the speed fluctuation data is stored in ROM 18, and when printing on the medium 2, the ejection control unit 17 generates a trigger signal based on the print data and the speed fluctuation data, and drives the piezoelectric element 9 to eject ink from the head 3. Below, we will explain how to measure the carriage speed to measure the speed fluctuation of the carriage 4, how to generate the speed fluctuation data, and how to control the ejection of ink from the head 3 when printing on the medium 2.

[0031] (Method for measuring carriage speed and generating speed fluctuation data) Fig. 3 is a schematic diagram illustrating the state of the printer 1 when measuring the speed fluctuation of the carriage 4 shown in Fig. 1. Fig. 4 is a diagram illustrating a method for generating the speed fluctuation data stored in the control unit 7 shown in Fig. 2.

[0032] Measurement of the speed fluctuation of the carriage 4 is performed after the printer 1 is assembled and before the printer 1 is shipped. Furthermore, measurement of the speed fluctuation of the carriage 4 is performed individually for each assembled printer 1. The speed fluctuation of the carriage 4 is measured for each resolution. That is, in this embodiment, for example, the speed fluctuation of the carriage 4 when printing at 600 dpi, the speed fluctuation of the carriage 4 when printing at 800 dpi, and the speed fluctuation of the carriage 4 when printing at 1200 dpi are measured.

[0033] To measure the speed fluctuation of the carriage 4, a linear encoder 24 is used to detect the position of the carriage 4 in the main scanning direction. The linear encoder 24 is a measuring device for measuring the speed fluctuation of the carriage 4. The linear encoder 24 includes a linear scale 25 and a sensor 26 for detecting the linear scale 25. The linear scale 25 is formed, for example, in the shape of a long, thin rectangular plate. The linear scale 25 has, for example, a plurality of slit-shaped through-holes that penetrate the linear scale 25 in the thickness direction of the linear scale 25. The sensor 26 is, for example, a reflective optical sensor. The sensor 26 outputs a rectangular pulse signal. That is, the output signal S1 of the linear encoder 24 is a rectangular pulse signal (see FIG. 4).

[0034] When measuring the speed fluctuation of the carriage 4, first, as shown in FIG. 3, the linear scale 25 is attached to the Y bar 5 and the sensor 26 is attached to the carriage 4 (linear encoder attachment process). In the linear encoder attachment process, the linear scale 25 is attached to the Y bar 5 so that the longitudinal direction of the linear scale 25 coincides with the main scanning direction. Also in the linear encoder attachment process, the sensor 26 is attached to the carriage 4 so that the light-emitting unit and the light-receiving unit of the sensor 26 face the linear scale 25. The sensor 26 is also electrically connected to the control unit 7. Specifically, the sensor 26 is electrically connected to the discharge control unit 17 (see FIG. 2).

[0035] Thereafter, the carriage 4 is caused to move back and forth in the main scanning direction, and the speed of the carriage 4 is measured based on the detection results of the sensor 26 (speed measurement process). In the speed measurement process, the speed of the carriage 4 at each resolution is measured. That is, in the speed measurement process, the carriage 4 is moved at multiple speeds corresponding to each resolution, and the speed of the carriage 4 at each resolution is measured. Thereafter, the linear scale 25 is removed from the Y-bar 5, and the sensor 26 is removed from the carriage 4 (linear encoder removal process). That is, once the speed of the carriage 4 has been measured, the linear encoder 24 is removed from the printer 1. Therefore, the linear encoder 24 is not attached to the printer 1 when it is shipped.

[0036] In the speed measurement process, the discharge control unit 17 measures the pulse interval (N1, N2, N3, ..., see FIG. 4) of one period of the output signal S1 of the linear encoder 24 (i.e., the output signal of the sensor 26). When measuring the pulse interval of one period of the output signal S1, the discharge control unit 17 generates a clock signal inside the discharge control unit 17. The discharge control unit 17 counts the number of clocks of the clock signal for one period of the output signal S1 and regards this number of clocks as the pulse interval.

[0037] Thereafter, the discharge control unit 17 generates a dpi-based count value based on the count value of the number of clock pulses of the clock signal for one cycle of the output signal S1, and a collection of these count values ​​is used as speed fluctuation data. The speed fluctuation data is associated with the position of the carriage 4 in the main scanning direction and with the resolution. The discharge control unit 17 also stores the speed fluctuation data in RAM (Random Access Memory) of the discharge control unit 17. The control unit 7 reads out the speed fluctuation data stored in the RAM of the discharge control unit 17 and saves it in ROM 18.

[0038] (Control of ink ejection from inkjet head when printing on media) Before the printer 1 prints on the medium 2, the control unit 7 reads out the speed fluctuation data stored in the ROM 18 and saves it in the RAM of the discharge control unit 17. When print data is input from the PC 19 to the control unit 7 and the printer 1 prints on the medium 2, the control unit 7 controls the motor 11 based on data such as resolution included in the print data, and moves the carriage 4 in the main scanning direction at a speed according to the resolution.

[0039] Furthermore, when printing on the medium 2 is performed by the printer 1, the ejection control unit 17 generates a trigger signal for ejecting ink from the head 3 based on data such as the print range and print position included in the print data and speed fluctuation data corresponding to the resolution. That is, the ejection control unit 17 generates the trigger signal by linking the print range and print position data included in the print data with the speed fluctuation data. The ejection control unit 17 also generates a trigger signal each time the count value of the clock signal included in the speed fluctuation data reaches a predetermined value, based on a clock signal generated internally by the ejection control unit 17. The piezoelectric element 9 is driven in response to the trigger signal. When the piezoelectric element 9 is driven, ink is ejected from the head 3.

[0040] (Main effect of this form) As described above, in this embodiment, the speed fluctuations at each resolution of the carriage 4, which moves back and forth in the main scanning direction, are measured in advance using the linear encoder 24, which is a measuring device, before shipping the printer 1. Also, in this embodiment, speed fluctuation data generated by measuring the speed fluctuations at each resolution of the carriage 4 in advance is stored in the control unit 7, and during printing, the control unit 7 ejects ink from the head 3 based on the print data and the speed fluctuation data.

[0041] Therefore, in this embodiment, even if the printer 1 does not have a linear encoder for detecting the position of the carriage 4 in the main scanning direction, and even if the speed of the carriage 4 reciprocating in the main scanning direction fluctuates, it is possible to ensure printing accuracy on the medium 2. Therefore, in this embodiment, it is possible to reduce the cost of the printer 1 and ensure printing accuracy on the medium 2 even if the speed of the carriage 4 reciprocating in the main scanning direction fluctuates.

[0042] (Example of a method for measuring carriage speed and changing ink ejection control) In measuring the speed fluctuation of the carriage 4 at each resolution, which is performed before shipping the printer 1, the rotary encoder 13 may be used instead of the linear encoder 24. That is, the speed fluctuation of the carriage 4 at each resolution may be measured using the rotary encoder 13. In this case, the carriage speed measurement method for measuring the speed fluctuation of the carriage 4 at each resolution includes a speed measurement step of moving the carriage 4 back and forth in the main scanning direction and measuring the speed of the carriage 4 at each resolution based on the detection results of the rotary encoder 13.

[0043] As in the embodiment described above, in the speed measurement step, the discharge control unit 17 measures the pulse interval for one period of the output signal of the rotary encoder 13 (i.e., the output signal of the sensor 16). At this time, the discharge control unit 17 generates a clock signal inside the discharge control unit 17. The discharge control unit 17 counts the number of clock pulses of the clock signal for one period of the output signal of the rotary encoder 13 and sets this number of clock pulses as the pulse interval. The discharge control unit 17 also generates a dpi-based count value based on the count value of the number of clock pulses of the clock signal, and sets this count value as speed fluctuation data. The discharge control unit 17 stores the speed fluctuation data in the RAM of the discharge control unit 17. The control unit 17 reads out the speed fluctuation data stored in the RAM of the discharge control unit 17 and saves it in the ROM 18.

[0044] Here, according to the investigations of the present inventors, a linear encoder 24 was installed in the printer 1, and it was found that there was a certain time difference between the speed fluctuations of the carriage 4 at each resolution measured using the linear encoder 24 and the speed fluctuations of the carriage 4 at each resolution measured using the rotary encoder 13. Specifically, the speed of the carriage 4 at each resolution measured using the rotary encoder 13 and the speed of the carriage 4 at each resolution measured using the linear encoder 24 fluctuate in the same manner, but the investigations of the present inventors revealed that, due to the influence of the power transmission mechanism 12, the speed of the carriage 4 at each resolution measured using the rotary encoder 13 is slower than the speed of the carriage 4 at each resolution measured using the linear encoder 24.

[0045] Therefore, in this modified example, when printing is performed on the medium 2 by the printer 1, the ejection control unit 17 generates a trigger signal to eject ink from the head 3 based on a predetermined correction value that takes into account the delay in the speed of the carriage 4 measured using the rotary encoder 13 relative to the speed of the carriage 4 measured using the linear encoder 24, data on the printing range and printing position included in the printing data, and speed fluctuation data according to the resolution.

[0046] That is, the control unit 7 generates a trigger signal based on the correction value, print data, and speed fluctuation data during printing. When generating the trigger signal, the ejection control unit 17 shifts the speed fluctuation data by an amount corresponding to the delay in the speed of the carriage 4 and uses this shifted speed fluctuation data. The correction value is calculated in advance using a specific printer 1. This correction value is stored in ROM 18, and before printing on the medium 2 with the printer 1, the control unit 7 reads out the correction value stored in ROM 18 and saves it in the RAM of the ejection control unit 17.

[0047] In this modified example, the control unit 7 generates a trigger signal based on a predetermined correction value, print data, and speed fluctuation data during printing. Therefore, even if the speed fluctuation of the carriage 4 at each resolution is measured using the rotary encoder 13, it is possible to ensure printing accuracy on the medium 2. Furthermore, in this modified example, there is no need to attach or detach the linear scale 25 and sensor 26 when measuring the speed fluctuation of the carriage 4, making it easy to measure the speed fluctuation of the carriage 4.

[0048] (Other embodiments) The above-described embodiment is one example of a preferred embodiment of the present invention, but the present invention is not limited to this embodiment and various modifications can be made without departing from the spirit of the present invention.

[0049] In the above-described embodiment, the sensor 26 may be a transmission-type optical sensor. In this case, the linear scale 25 is disposed between the light-emitting portion and the light-receiving portion of the sensor 26. The sensor 26 may also be a magnetic sensor. In this case, the linear scale 25 is a magnetic scale, and instead of the plurality of through-holes, the linear scale 25 is formed with a plurality of detectable portions made of a magnetic material.

[0050] In the above-described embodiment, the sensor 16 may be a reflective optical sensor. In this case, the light-emitting portion and the light-receiving portion of the sensor 16 are arranged opposite a portion of the rotary scale. The sensor 16 may also be a magnetic sensor. In this case, the rotary scale is a magnetic scale, and the rotary scale has a plurality of detectable portions made of a magnetic material instead of a plurality of through holes.

[0051] In the above-described embodiment, the carriage drive mechanism 6 does not have to include the rotary encoder 13. Also, in the above-described embodiment, the printer 1 may include, instead of the platen 8, a table on which the medium 2 is placed and a table drive mechanism that moves the table in the sub-scanning direction. Also, the printer 1 may include a table on which the medium 2 is placed and a Y-bar drive mechanism that moves the Y-bar 5 in the sub-scanning direction. Also, the inkjet printer to which the present invention is applied may be a 3D printer. [Explanation of symbols]

[0052] 1. Printer (inkjet printer) 3 heads (inkjet heads) 4 carriages 5 Y bar (carriage support member) 6 Carriage drive mechanism 7 Control Unit 11 Motor 12 Power transmission mechanism 13 Rotary Encoder 25 Linear Scale 26 sensors Y main scanning direction

Claims

1. In an inkjet printer that prints by ejecting ink, an inkjet printer including an inkjet head that ejects ink, a carriage on which the inkjet head is mounted, a carriage drive mechanism that moves the carriage in a main scanning direction, and a control unit that controls the inkjet printer; The control unit stores speed fluctuation data generated by measuring in advance the speed fluctuation of the carriage that moves back and forth in the main scanning direction during printing at each resolution, and print data for printing is input before printing, The control unit generates a trigger signal for ejecting ink from the inkjet head based on the print data and the speed fluctuation data during printing, and ejects ink from the inkjet head.

2. the carriage drive mechanism includes a motor, a power transmission mechanism for transmitting power of the motor to the carriage, and a rotary encoder for detecting a rotation speed of the motor; The speed fluctuation of the carriage at each resolution is measured using the rotary encoder; 2. The inkjet printer according to claim 1, wherein the control unit generates the trigger signal based on a predetermined correction value, the print data, and the speed fluctuation data during printing.

3. 2. A carriage speed measurement method for measuring a carriage speed fluctuation at each resolution in an inkjet printer according to claim 1, comprising: a linear encoder mounting step of mounting a linear scale on a carriage support member that movably supports the carriage, and mounting a sensor to the carriage for detecting the linear scale; a speed measurement step of reciprocating the carriage in a main scanning direction after the linear encoder installation step and measuring the speed of the carriage at each resolution based on the detection result of the sensor; a linear encoder removing step of removing the linear scale from the carriage support member and removing the sensor from the carriage after the speed measuring step.

4. 3. A carriage speed measuring method for measuring carriage speed fluctuations at each resolution in an inkjet printer according to claim 2, comprising: A carriage speed measuring method comprising a speed measuring step of reciprocating the carriage in a main scanning direction and measuring the speed of the carriage at each resolution based on the detection result of the rotary encoder.

5. 5. A carriage speed measuring method according to claim 3, wherein the carriage speed fluctuation at each resolution is measured for each of the inkjet printers.

6. A control method for an inkjet printer including an inkjet head that ejects ink, a carriage on which the inkjet head is mounted, and a carriage drive mechanism that moves the carriage in a main scanning direction, comprising: speed fluctuation data generated by measuring in advance the speed fluctuation of the carriage that moves back and forth in the main scanning direction during printing at each resolution is stored; A control method for an inkjet printer, characterized in that, during printing, a trigger signal for ejecting ink from the inkjet head is generated based on print data for printing and the speed fluctuation data, and ink is ejected from the inkjet head.

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