JP2006137124A - Liquid ejecting apparatus and liquid ejection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust a driving voltage value without carrying out measurement of a fly speed of ink and a dot width for every nozzle at each time even when an environmental condition changes by some degrees. <P>SOLUTION: The liquid ejecting apparatus comprises a recording head 4 with a plurality of piezoelectric elements 6 set corresponding to a plurality of the nozzles 5; a head driving part 25 with driving voltage setting parts 27 which set a driving voltage to be applied to the piezoelectric element 6 for every nozzle 5; an input part 24 which carries out an inputting for adjustment start of the driving voltage value to be transmitted to the driving voltage setting parts 27; a detecting part 19 which detects the fly speed of the ink ejected from the nozzle 5 by a start signal from the input part 24; a control part 22 which determines the driving voltage value for making the fly speed of the ink ejected from the nozzle 5 agree with a target speed on the basis of the detection result of the detecting part 19, and sets the value into the driving voltage setting part 27; and a storage part 23 which stores the driving voltage value determined by the control part 22. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid discharge apparatus and a liquid discharge method, and more particularly, to a liquid discharge apparatus and a liquid discharge method for generating a drive waveform signal for driving a recording head.

  Conventionally, an ink jet recording apparatus or the like is generally known as a liquid ejection apparatus that records an image on a recording medium such as paper. The ink jet recording apparatus is equipped with a recording head that ejects ink from a plurality of nozzles. Further, the recording head is provided with an ejection energy generating element corresponding to each nozzle in order to eject ink from each of the plurality of nozzles. As this discharge energy generating element, a heat generating element that generates bubbles by heat and discharges ink by the pressure of the bubbles, a piezoelectric element that discharges ink by applying pressure to the ink by deformation, and the like are known. Hereinafter, a piezoelectric element will be described as an example of the discharge energy generating element.

  A piezoelectric element, which is an ejection energy generating element, is connected to a drive circuit. The piezoelectric element expands and contracts based on a drive signal input from the drive circuit and ejects ink from a nozzle. By the way, even if a drive signal having the same voltage value is applied to each nozzle, variations in the deformation speed and deformation rate of the piezoelectric element occur due to individual differences between the nozzles. This variation causes variations in the flying speed of the ink ejected from each nozzle, which has been an adverse effect of high-definition image recording.

  Therefore, in recent years, a liquid ejection apparatus has been developed that measures the ejection speed and ejection amount of ink and corrects the voltage value based on the measured values.

For example, the liquid ejecting apparatus described in Patent Document 1 includes a storage memory that stores correction data for correcting variations in a substrate having an ejection energy generating element for each recording head, and the correction data read from the storage memory. Based on the above, a uniform image having no variation between the substrates is formed. The liquid ejection device described in Patent Document 2 measures the flying speed of ink ejected from each nozzle and returns it to the nozzle drive circuit of the recording head. The liquid ejection device described in Patent Document 3 The voltage applied to the electrothermal conversion element of each nozzle is adjusted according to the insulation method of the resistor, and the ink discharge amount between the nozzles is made uniform. Further, the liquid ejection device described in Patent Document 4 sets ink density data corresponding to the dot width printed on a recording medium. Further, the liquid ejection device described in Patent Document 5 changes the amount of ink droplets ejected from each nozzle based on the detection result of the test pattern, and the liquid ejection device described in Patent Document 6 In this method, the voltage applied to the piezoelectric element is set for each ink ejection section so that the flying speed of the ink ejected from each nozzle is within a desired specified speed range. In addition, the liquid ejection devices described in Patent Literature 7 and Patent Literature 8 make the flying speed of ink ejected from each nozzle uniform by changing the rise and fall time constants of the voltage applied to the piezoelectric element. Is. Furthermore, the liquid ejection device described in Patent Document 9 measures the flying speed of the ink ejected from each nozzle, and determines the pulse width of the drive signal for each nozzle based on the result.
Japanese Patent Laid-Open No. 7-224004 Japanese Patent Application Laid-Open No. 7-256884 Japanese Patent Laid-Open No. 9-131872 JP 10-235905 A JP 2001-232775 A JP 2002-200722 A JP 2002-316414 A JP 2002-331661 A JP 2003-145736 A

  However, all of the liquid ejection devices described in Patent Documents 1 to 9 are configured to adjust the flying speed of ink in units of nozzles.

  On the other hand, the flying speed of the ink also occurs in the recording head unit as the ink viscosity changes due to the environmental temperature. In this case also, it is necessary to make the dispersion of the droplet speed uniform. However, in the above-described liquid ejecting apparatus, even if the flying speed and dot width of the ink are accurately measured for each nozzle and the drive voltage value is corrected, if the environmental conditions such as room temperature change, the ink flying again for each nozzle. The speed and dot width were measured, and the drive voltage value of each nozzle had to be adjusted.

  The present invention has been made in view of the above points. Even if the environmental conditions change to some extent after adjusting the drive voltage value, the ink flying speed and dot width are measured for each nozzle each time. An object of the present invention is to provide a liquid ejection apparatus and a liquid ejection method that can adjust the drive voltage value without any problems.

  In order to solve the above-mentioned problem, the invention described in claim 1 is a liquid ejection apparatus, and includes a recording head having a plurality of piezoelectric elements provided corresponding to a plurality of nozzles, and a driving voltage applied to the piezoelectric elements. By a head drive unit having a drive voltage setting unit for setting each of the plurality of nozzles, an input unit for performing adjustment start input of a drive voltage value transmitted to the drive voltage setting unit, and a start signal from the input unit, A detection unit that detects ink droplets ejected from the plurality of nozzles, and a driving voltage for matching the flying speed of the ink ejected from the plurality of nozzles with a target speed based on the detection result of the detection unit. It has a control part which determines a value and sets it in the drive voltage setting part, and a storage part which memorizes a drive voltage value which the control part determined.

  According to the first aspect of the present invention, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed is calculated for each nozzle and set in the drive voltage setting unit. In the head unit, it is possible to treat that the flying speed of ink does not vary. Further, the adjustment of the drive voltage value is started by the drive voltage adjustment start input in the input unit, and the calculated drive voltage value is stored in the storage unit. Therefore, the adjustment until the drive voltage value adjustment is performed again is stored. The recording head is driven by the driving voltage value of each nozzle stored in the section.

  The invention according to claim 2 is the liquid ejecting apparatus according to claim 1, wherein the detection unit measures the flying speed of the ink by measuring the time from the start of ink ejection to the detection of the ink droplet. The control unit calculates a driving voltage value for setting the ink flying speed to a target speed based on the ink flying speed measured by the detecting unit.

  According to the second aspect of the present invention, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed can be calculated based on the flying speed of the ink measured by the detection unit. it can.

  The invention according to claim 3 is the liquid ejecting apparatus according to claim 1, wherein the detection unit measures an ink flying speed by calculating an area of the detected ink droplet, and the control unit A drive voltage value for setting the ink flying speed to the target speed is calculated based on the ink flying speed measured in the detection unit.

  According to the third aspect of the present invention, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed can be calculated based on the area of the ink droplet calculated by the detection unit. it can.

  The invention according to claim 4 is the liquid ejecting apparatus according to any one of claims 1 to 3, wherein the flying speed of ink reaches a target speed for all the nozzles provided in the recording head, The detection of the ink droplet by the detection unit and the determination and setting of the drive voltage value by the control unit are repeated.

  According to the fourth aspect of the present invention, the flying speed of the ink ejected from each nozzle can be surely matched with the target speed.

  The invention according to claim 5 is the liquid ejection device according to any one of claims 1 to 4, wherein the control unit is configured to store the storage unit when power is supplied to the liquid ejection device. The driving voltage value determined so that the flying speed of the ink ejected from each nozzle matches the target speed is read out and reset in the driving voltage setting unit.

  According to the fifth aspect of the present invention, since the drive voltage value for making the ink flying speed of each nozzle coincide with the target speed when the power to the liquid ejecting apparatus is turned on is read from the storage unit, It is not necessary to adjust the drive voltage by detecting the ink flying speed of each nozzle each time the power is turned on.The drive voltage value read from the storage unit is reset in the drive voltage setting unit, and each nozzle of the recording head is set. Can be driven.

  A sixth aspect of the present invention is the liquid ejection apparatus according to any one of the first to fifth aspects, further comprising a temperature sensor that measures the temperature of the recording head, and the control unit includes the temperature. The target speed of the flying speed of the ink ejected from each nozzle after the change of the temperature of the recording head is determined again based on the measurement result of the sensor.

  According to the sixth aspect of the present invention, after the drive voltage value is set for each nozzle so that the flying speed of the ink ejected from all the nozzles matches the target speed, the ink temperature changes, and the recording head unit. Even when the target speed deviates, the target speed can be quickly optimized according to the temperature change.

  A seventh aspect of the present invention is the liquid ejection apparatus according to any one of the first to sixth aspects, wherein the storage unit stores an LUT, and the control unit uses the LUT to drive voltage. It is characterized by determining a value.

  According to the seventh aspect of the invention, the control configuration can be simplified by using the LUT.

  The invention according to claim 8 is a liquid ejection method, wherein a plurality of piezoelectric elements are provided corresponding to the plurality of nozzles in a head driving unit that drives the recording head, and are provided corresponding to the plurality of nozzles. An input step for performing an adjustment start input of the drive voltage value to be transmitted to the drive voltage setting unit for setting the drive voltage to be applied to each of the plurality of nozzles in the input unit, and a start signal from the input unit, in the detection unit A detection process for detecting ink droplets ejected from a plurality of nozzles, and a drive for causing the flying speed of the ink ejected from the plurality of nozzles to coincide with a target speed in the control unit based on the detection result of the detection unit The method includes a setting step of determining a voltage value and setting the voltage value in the driving voltage setting unit, and a storage step of storing the driving voltage value determined by the control unit.

  According to the eighth aspect of the invention, since the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed is calculated for each nozzle and set in the drive voltage setting unit, the recording is performed. In the head unit, it is possible to treat that the flying speed of ink does not vary. Further, the adjustment of the drive voltage value is started by an input for starting the adjustment of the drive voltage in the input process, and the calculated drive voltage value is stored in the storage unit in the storage process, so that the adjustment of the drive voltage value is executed again. The recording head is driven by the driving voltage value of each nozzle stored in the storage unit.

  A ninth aspect of the present invention is the liquid ejection method according to the eighth aspect, wherein in the detection step, the flying speed of the ink is measured by measuring the time from the start of the ejection of the ink to the detection of the ink droplet. The setting step calculates a drive voltage value for setting the ink flying speed to the target speed based on the ink flying speed measured in the detecting step.

  According to the ninth aspect of the present invention, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed can be calculated based on the flying speed of the ink measured in the detection step. it can.

  A tenth aspect of the present invention is the liquid ejection method according to the eighth aspect, wherein the detecting step measures the flying speed of the ink by calculating the area of the detected ink droplet, and the setting step includes A drive voltage value for setting the ink flying speed to the target speed is calculated based on the ink flying speed measured in the detection unit.

  According to the invention described in claim 10, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed can be calculated based on the area of the ink droplet calculated in the detection step. it can.

  Invention of Claim 11 is the liquid discharge method as described in any one of Claims 8-10, Comprising: Until the flying speed of ink becomes target speed about all the nozzles with which the said recording head is equipped, The detection of ink droplets in the detection step and the determination and setting of drive voltage values in the setting step are repeated.

  According to the eleventh aspect of the present invention, the flying speed of the ink ejected from each nozzle can be surely matched with the target speed.

  A twelfth aspect of the present invention is the liquid ejection method according to any one of the eighth to eleventh aspects, wherein when the power is supplied to the liquid ejection device, each nozzle is ejected from the storage unit. It has a resetting step of reading out the driving voltage value determined so that the flying speed of the ejected ink matches the target speed and resetting it in the driving voltage setting unit.

  According to the twelfth aspect of the present invention, since the drive voltage value for making the ink flying speed of each nozzle coincide with the target speed when the power to the liquid ejecting apparatus is turned on is read from the storage unit, It is not necessary to adjust the drive voltage by detecting the ink flying speed of each nozzle each time the power is turned on.The drive voltage value read from the storage unit is reset in the drive voltage setting unit, and each nozzle of the recording head is set. Can be driven.

  A thirteenth aspect of the present invention is the liquid ejection method according to any one of the eighth to twelfth aspects, including a head temperature measuring step of measuring the temperature of the recording head by a temperature sensor, In the setting step, the target speed of the flying speed of the ink ejected from each nozzle after the change of the temperature of the recording head is determined again based on the measurement result of the temperature sensor.

  According to the thirteenth aspect of the present invention, after the drive voltage value is set for each nozzle so that the flying speed of the ink ejected from all the nozzles matches the target speed, the ink temperature changes, and the recording head unit. Even when the target speed deviates, the target speed can be quickly optimized according to the temperature change.

  A fourteenth aspect of the present invention is the liquid ejection method according to any one of the eighth to thirteenth aspects, wherein an LUT in which an ink temperature is associated with a driving voltage value is stored in the storage step. In the setting step, the drive voltage value is determined by LUT.

  According to the invention described in claim 14, the control configuration can be simplified by using the LUT.

  According to the first aspect of the present invention, once the drive voltage value is set for each nozzle, it is possible to treat the ink flying speed as being uniform for each recording head, and the control configuration is simplified. Further, since the recording head is driven by the driving voltage value of each nozzle stored in the storage unit until the adjustment of the driving voltage value is performed again, the recording head can be driven promptly.

  According to the second aspect of the present invention, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed can be calculated based on the flying speed of the ink measured by the detection unit. it can.

  According to the third aspect of the present invention, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed can be calculated based on the area of the ink droplet calculated by the detection unit. it can.

  According to the fourth aspect of the present invention, the flying speed of the ink ejected from each nozzle can be surely matched with the target speed.

  According to the fifth aspect of the present invention, it is not necessary to adjust the driving voltage by detecting the ink flying speed of each nozzle every time the power is turned on, and the recording head can be driven promptly. .

  According to the sixth aspect of the present invention, even when the ink temperature changes with changes in environmental conditions such as room temperature and the target speed deviates in units of recording heads, the ink flying speed and the dot width of each nozzle are newly renewed. It is possible to quickly optimize the target speed without performing the measurement.

  According to the invention described in claim 7, it is possible to adjust the drive voltage quickly by simplifying the control by using the LUT.

  According to the eighth aspect of the present invention, once the drive voltage value is set for each nozzle, it is possible to handle the recording head as if there is no variation in the flying speed of the ink, and the control configuration is simplified. Further, since the recording head is driven by the driving voltage value of each nozzle stored in the storage unit until the adjustment of the driving voltage value is performed again, the recording head can be driven promptly.

  According to the ninth aspect of the present invention, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed can be calculated based on the flying speed of the ink measured by the detection unit. it can.

  According to the tenth aspect of the present invention, the drive voltage value for making the flying speed of the ink ejected from each nozzle coincide with the target speed can be calculated based on the area of the ink droplet calculated by the detection unit. it can.

  According to the eleventh aspect of the present invention, the flying speed of the ink ejected from each nozzle can be surely matched with the target speed.

  According to the twelfth aspect of the present invention, it is not necessary to adjust the driving voltage by detecting the ink flying speed of each nozzle every time the power is turned on, and the recording head can be driven promptly. .

  According to the thirteenth aspect of the present invention, even when the ink temperature changes with a change in environmental conditions such as room temperature and the target speed deviates in units of recording heads, the ink flying speed and the dot width of each nozzle are newly determined. It is possible to quickly optimize the target speed without performing the measurement.

  According to the fourteenth aspect of the present invention, it is possible to adjust the drive voltage quickly by simplifying the control by using the LUT.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the liquid ejection apparatus 1 has a rod-shaped guide rail 2, and a carriage 3 is supported on the guide rail 2. The carriage 3 reciprocates along the guide rail 2 in the main scanning direction X by a carriage drive mechanism (not shown).

  The carriage 3 ejects four process color inks of yellow (Y), magenta (M), cyan (C), and black (K) toward the recording surface of the recording medium P based on the image data. A recording head 4 is mounted. The recording head 4 in this embodiment is a serial type recording head 4 that reciprocates with the carriage 3. The recording head 4 has a nozzle surface facing the recording surface of the recording medium P, and a plurality of nozzles 5 (see FIG. 2) are arranged along the sub-scanning direction Y orthogonal to the main scanning direction X on the nozzle surface. Yes.

  The recording head 4 has a piezoelectric element 6 as shown in FIG. A flow path plate 7 is provided at a position facing the piezoelectric element 6, and an ink flow path 8 is formed by the piezoelectric element 6 and the flow path plate 7. In addition, one end of the ink flow path 8 communicates with the nozzle 5, and the other end communicates with the liquid chamber 9.

  In addition, a head driving unit 27 (see FIG. 4) is connected to the piezoelectric element 6 via the electrode 10 and the lead wire 11.

  Further, in the vicinity of the recording head 4, a temperature sensor 12 (see FIG. 4) that is a temperature measuring unit that measures the temperature of the recording head 4 is provided. The temperature sensor 12 is for indirectly measuring the ink temperature. However, instead of measuring the temperature of the recording head 4, the ink temperature may be indirectly measured by measuring the ambient temperature. Good.

  As shown in FIG. 1, the central part of the movable range of the carriage 3 is a recording area A for recording on the recording medium P. In this recording area A, the recording medium P is placed horizontally from the non-recording surface. A supporting platen 13 is provided.

  Further, the outer end of the recording area A which is the movable range of the carriage 3 is a home position area B which is a standby position of the carriage 3, and the nozzle 5 is provided in the home position area B during the standby of the carriage 3. The number of moisturizing caps 14 for moisturizing the nozzle surface on which is formed corresponds to the number corresponding to the recording head 4.

  The other end of the recording area A, which is the movable range of the carriage 3, is a cleaning area C for cleaning the recording head 4. In the cleaning area C, a cleaning unit 15 is provided. The cleaning unit 15 covers the nozzle surface of the recording head 4 and sucks the ink inside the nozzle 5 to be discharged from the recording head 4. An ink collecting portion 17 for collecting the ink and a blade 18 for wiping off ink remaining on the nozzle surface.

  The ink recovery unit 17 is formed in a box shape having an opening on the side toward the recording head 4. As shown in FIG. 3, the ink recovery unit 17 is discharged from each nozzle 5 of the recording head 4 to the inner wall of the ink recovery unit 17. A speed sensor is provided as a detection unit 19 that detects ink droplets. The speed sensor includes a light emitting element 20 and a light receiving element 21 that are disposed to face the inner wall of the ink collection unit 17. The light emitting element 20 and the light receiving element 21 continuously discharge from each nozzle 5. The ink flying speed is equivalently measured by detecting a plurality of ink droplets and measuring the time from the start of ink ejection to the detection of the ink droplets.

  In this embodiment, a speed sensor is used. However, a detection unit 19 that detects ink droplets ejected from each nozzle 5 uses a strobe and a microscope to detect ink droplets with a CCD area sensor, and performs image processing. It is also possible to measure the ink flying speed equivalently by calculating the area of the ink droplet.

  Further, the liquid ejection apparatus 1 is provided with a transport mechanism (not shown) for feeding the recording medium P in the sub-scanning direction Y. This transport mechanism transports the recording medium P intermittently by repeating the transport and stop of the recording medium P in accordance with the operation of the carriage 3 during image recording.

  In addition, an upper part of a casing (not shown) of the liquid ejection device 1 is configured by an LCD (Liquid Crystal Display) or the like, and various operation buttons or the An input unit 24 is provided for displaying the status of the apparatus and the operation status of each function.

  As shown in FIG. 4, the liquid ejection apparatus 1 of this embodiment includes a control unit 22. The control unit 22 includes a CPU, a RAM, and a ROM (all not shown), and a processing program recorded in the ROM is developed on the RAM, and the processing program is executed by the CPU. In addition to the storage unit 23, the input unit 24, the detection unit 19, and the temperature sensor 12, the recording head 4 is electrically connected to the control unit 22 via the head drive unit 25. Each component is driven and controlled.

  In the recording head 4, when a driving signal is supplied from the head driving unit 25 to the electrode 10 of the piezoelectric element 6 and the electrode 10 applies a voltage based on the driving signal to the piezoelectric element 6, the nozzle 5 is deformed by the deformation of the piezoelectric element 6. Ink is discharged from the nozzle. That is, due to the deformation of the piezoelectric element 6, the inside of the ink flow path 8 becomes negative pressure when the ink flow path 8 expands, and the ink is guided to the inside of the ink flow path 8, and when contracted, the ink flow path 8 The ink inside the ink flow path 8 is ejected from the nozzle 5 by the positive pressure inside.

  The speed sensor as the detection unit 19 detects a plurality of ink droplets ejected from each nozzle 5 continuously by the light emitting element 20 and the light receiving element 21 of the speed sensor 19 based on an instruction signal from the control unit 22. The ink flying speed is equivalently measured by measuring the time from the start of ink ejection until the ink droplet is detected, and the measurement result is output to the control unit 22. In addition, a strobe and a microscope are used as the detection unit 19, and the ink flying speed can be equivalently measured by calculating the area of the ink droplet by image processing.

  The temperature sensor 12 measures the temperature of the recording head 4 and outputs the measurement result to the control unit 22.

  The storage unit 23 is configured by an EPROM (Erasable Programmable Read Only Memory), a FRAM (Ferroelectric Random Access Memory), an MRAM (Magnetic Random Access Memory), or a flash memory, which is a writable nonvolatile storage medium, and is controlled. A drive voltage value or the like for setting the flying speed of the ink calculated in the unit 22 to the target speed is stored.

  As shown in FIG. 5, the head drive unit 25 includes a drive waveform creation unit 26 that creates a waveform of a drive signal corresponding to the piezoelectric element 6 based on a control signal from the control unit 22. The head driving unit 25 includes a driving voltage setting unit 27 that is provided corresponding to each nozzle 5 and sets the driving voltage value calculated by the control unit 22 for each nozzle. The driving voltage setting unit 27 includes: A D / A converter that converts an output signal from the control unit 22 into an analog signal is provided. Furthermore, the head drive unit 25 includes an amplifier 28 that synthesizes and amplifies the drive signal from the drive waveform generation unit 26 and the output signal of the drive voltage setting unit 27, and also includes a buffer circuit with a low output impedance, A current buffer 29 is provided to increase the amount of current to a value at which the nozzle 5 can be driven in response to the 28 output signals.

  The input unit 24 is configured by an LCD (Liquid Crystal Display), and displays various operation buttons, device status display, operation status of each function, and the like on the display screen according to instructions of a display signal input from the control unit 22. It is like that. The LCD display screen is covered with a pressure-sensitive (resistive film pressure) touch panel configured with transparent electrodes arranged in a grid, and the XY coordinates of the force point pressed with a finger or a touch pen are expressed as voltage values. The detected position signal Sx is output to the control unit 22 as an operation signal. The input unit 29 includes various operation buttons such as a numeric button and a start button, and outputs an operation signal generated by the button operation to the control unit 22. With such a configuration, the input unit 24 can perform adjustment start input of the drive voltage value transmitted to the drive voltage setting unit 27 and measurement start input of the temperature of the recording head 4 by the temperature sensor 12. ing.

  The control unit 22 drives a speed sensor as the detection unit 19 when the adjustment start input is performed in the input unit 24. When it is determined that the ink flying speed is measured by the speed sensor for all the nozzles 5, the flying speed of the ink ejected from each nozzle 5 is set to the target speed based on the ink flying speed measured by the detection unit 19. The drive voltage value for achieving this is calculated. The drive voltage value for setting the ink flying speed to the target speed can be calculated by, for example, the following equation (1).

Here, the target time Ttarget (t ₂ ) at t ₂ ° C in the above equation (1) corresponds to the target ink flying speed at t ₂ ° C, and the target ink flying speed. Since the target speed itself is linearly proportional to the environmental temperature, the speed is uniquely determined according to the temperature of the recording head 4 at the time of measuring the ink flying speed as shown in the following equation (2). It is obtained in advance through experiments or the like.

  In addition, when a strobe and a microscope are used as the detection unit 19 and the ink flying speed is measured by calculating the area of the ink droplet by image processing, the ink is ejected from each nozzle 5 by the following equation (3), for example. It is also possible to calculate a drive voltage value Vres for making the ink flying speed coincide with the target speed.

  When it is determined that the drive voltage value Vres for matching the ink flying speed to the target speed is calculated for all the nozzles 5, the drive voltage value Vres is set in the drive voltage setting unit 27. At this time, the control unit 22 determines whether or not the flying speed of the ink ejected from all the nozzles 5 has reached the target speed. A drive voltage value Vres for making the flying speed coincide with the target speed is calculated. And when the flying speed of the ink of all the nozzles 5 becomes target speed, the drive voltage value Vres set to the drive voltage setting part 27 is memorize | stored in a memory | storage part.

In addition, when the liquid ejection device 1 is turned off and then on again, the control unit 22 reads the previously set target time Ttarget (t ₂ ) and the drive voltage value Vres from the storage unit 23. . When there is no temperature change in the recording head 4 when the power is turned on, the previously set drive voltage value Vres is reset in the drive voltage setting unit 27. On the other hand, when there is a temperature change in the recording head 4 when the power is turned on, the target time Ttarget (t ₂ ) corresponding to the temperature is again determined by the above equation (2), and then the ink is calculated by the above equation (1). A drive voltage value Vres for making the flying speed coincide with the target time Ttarget (t ₂ ) is calculated and reset in the drive voltage setting unit 27.

In addition to the power-on of the liquid ejecting apparatus 1, the control unit 22 receives an ink temperature measurement start input from the input unit 24, or when the usage time of the liquid ejecting apparatus 1 reaches a predetermined time or When the number of recording media P reaches a predetermined number, the temperature sensor 12 is driven to measure the temperature of the recording head 4, and it is determined whether or not the temperature of the recording head 4 has changed. When the temperature of the recording head 4 is changed, the target time Ttarget (t ₂ ) corresponding to the target speed after the temperature of the recording head 4 is changed to t ₂ ° C. is determined by the above equation (2). The drive voltage value Vres for making it coincide with the target speed is calculated by the above formula (1) and stored in the storage unit 23.

Note that the above-described control configuration can be simplified by providing the storage unit 23 with an LUT. Here, the LUT is a look-up table in which a drive voltage value corresponding to a time from when a drive voltage is applied to the piezoelectric element 6 until an ink droplet is detected or an ink temperature is defined. That is, in the present embodiment, a driving voltage value corresponding to the measurement time until the ink droplet at t ₁ ° C. is detected is calculated by the above equation (1), and the measurement time and the calculated driving voltage value Vres are calculated. Is a table in which is previously associated. Further, the target time Ttarget (t ₂ ) corresponding to the temperature of the recording head 4 is determined by the above equation (2), and the temperature of the recording head 4 and the target time Ttarget (t ₂ ) are stored in association with each other in advance. Is also possible. Furthermore, the drive voltage value corresponding to the area of the ink droplet can be calculated by the above equation (3), and the area of the ink droplet and the calculated drive voltage value Vres can be stored in association with each other in advance.

  Next, the liquid discharge method of the present invention using the above-described liquid discharge apparatus 1 will be described with reference to the flowcharts of FIGS.

  As shown in FIG. 6, when the adjustment start input is performed by the input unit 24 (step S1), the control unit 22 drives the carriage drive mechanism to move the carriage 3 to the cleaning region C, and moves the head drive unit 25. The ink is driven to eject the ink from the nozzle 5 of the recording head 4 to the ink recovery unit 17 (step S2). The speed sensor as the detection unit 19 detects the ink droplet ejected for each nozzle 5 and measures the time from the start of ink ejection to the detection of the ink droplet, thereby equivalently measuring the flying speed of the ink. The measurement result is output to the control unit 22 (step S3). The control unit 22 determines whether or not the ink flying speed has been measured for all the nozzles 5 (step S4). If it is determined that there is a nozzle 5 for which the ink flying speed has not been measured, the nozzles are determined. Ink is ejected from 5 (step S2), and the flying speed of the ink is measured by the speed sensor (step S3).

  On the other hand, when the control unit 22 determines that the flying speed of the ink has been measured for all the nozzles 5, the control unit 22 determines the ink for each nozzle 5 according to the above equation (1) based on the measurement result of the speed sensor. A drive voltage value Vres is calculated so that the flight speed becomes the target speed (step S5). And the control part 22 judges whether the drive voltage value Vres for obtaining target time was calculated about all the nozzles 5 (step S6), and when there exists the nozzle 5 which has not calculated the drive voltage value Vres, A drive voltage value Vres for obtaining the target time for the nozzle 5 is calculated (step S5).

  On the other hand, if it is determined that the drive voltage value Vres for obtaining the target time is calculated for all the nozzles 5, the drive voltage value Vres is set in the drive voltage setting unit 27 (step S7).

  Thereafter, the control unit 22 causes ink to be ejected idle from the nozzle 5 in which the drive voltage value Vres for obtaining the target time is set, and the flying speed of the ink is measured by the speed sensor (step S8). Then, it is determined whether or not the flying speed of the ink ejected from all the nozzles 5 is the target speed (step S9). As a result, if there is a nozzle 5 whose ink flying speed is not equal to the target speed, the processes in and after step S5 are repeated.

  On the other hand, when the flying speed of the ink ejected from all the nozzles 5 reaches the target speed, the control unit 22 stores the drive voltage value Vres of each nozzle 5 in the storage unit (step S10) and adjusts the drive voltage value. The process ends. Then, when the use of the liquid ejecting apparatus 1 is finished, the power is turned off (step S11).

Next, when the power of the liquid ejecting apparatus 1 is turned on (step S12), the control unit 22 reads the previously set target time Ttarget (t ₂ ) and drive voltage value Vres from the storage unit 23 (step S13). Then, it is determined whether or not there is a temperature change in the recording head 4 when the power is turned on (step S14). As a result, if there is no temperature change in the recording head 4, the previously set drive voltage value Vres is reset in the drive voltage setting unit 27 (step S 15). On the other hand, if there is a temperature change in the recording head 4 when the power is turned on, the target time Ttarget (t ₂ ) corresponding to the temperature is again determined by the above equation (2) (step S16), and then the above equation (1) ) To calculate the drive voltage value Vres for making the ink flying speed coincide with the target time Ttarget (t ₂ ) (step S5) and reset it in the drive voltage setting unit 27 (step S7). Then, the head drive unit 25 is driven according to the set drive voltage value Vres to perform image recording processing.

  Note that the determinations in steps S4 and S6 may be omitted, and it may be determined in step S9 whether or not the flying speed of the ink ejected from each nozzle is the same as the target speed.

In addition to the power-on of the liquid ejection apparatus 1 shown in FIG. 6, the control unit 22, as shown in FIG. 7, when the ink temperature measurement start input is performed at the input unit 24, the liquid ejection apparatus 1. When the usage time of the recording head reaches a predetermined time or when the recording medium P reaches a predetermined number, the temperature sensor 12 is driven to measure the temperature of the recording head 4 (step S21). It is determined whether or not there is a change (step S22). If the temperature of the recording head 4 does not change, the target time Ttarget (t ₂ ) redetermination process ends. On the other hand, when there is a change in the temperature of the recording head 4, the target time Ttarget (t ₂ ) after the temperature of the recording head 4 has changed to t ₂ ° C according to the above equation (2) based on the measurement result of the temperature sensor 12. ) Is again determined (step S23) and stored in the storage unit 23 (step S24).

  As described above, according to the liquid ejection apparatus 1 or the liquid ejection method of the present embodiment, the drive voltage value Vres for making the flying speed of the ink ejected from each nozzle 5 coincide with the target speed is calculated for each nozzle 5. Since the setting is made in the drive voltage setting unit 27, it is possible to treat the ink flying speed as being uniform in the recording head 4 unit. Further, the adjustment of the drive voltage value is started by the drive voltage adjustment start input in the input unit 24, and the calculated drive voltage value is stored in the storage unit 23. Therefore, until the adjustment of the drive voltage value is executed again. The recording head 4 is driven based on the driving voltage value of each nozzle 5 stored in the storage unit 23.

  Further, a drive voltage value for making the flying speed of the ink ejected from each nozzle 5 coincide with the target speed based on the flying speed of the ink measured by the detecting unit 19 or the area of the ink droplet calculated by the detecting unit 19 is set. Can be calculated.

  Further, by repeating the detection of the ink droplets by the detection unit 19 and the determination and setting of the drive voltage value by the control unit 22, the flying speed of the ink ejected from each nozzle 5 can be reliably matched with the target speed.

  Further, it is not necessary to adjust the driving voltage by detecting the ink flying speed of each nozzle 5 every time the power is supplied to the liquid ejecting apparatus 1, and the driving voltage value read from the storage unit 23 is stored in the driving voltage setting unit 27. The nozzles 5 of the recording head 4 can be driven by resetting.

  Further, after the drive voltage value is set for each nozzle 5 so that the flying speed of the ink ejected from all the nozzles 5 matches the target speed, the ink temperature is changed and the target speed is shifted in units of the recording head 4. Even in this case, the target speed can be quickly optimized without measuring the ink flying speed and the dot width of each nozzle 5 each time.

  Further, the control can be simplified by using the LUT without performing the calculations according to the above equations (1) to (3) each time.

  As described above, according to the liquid ejecting apparatus 1 or the liquid ejecting method of the present invention, once the drive voltage value is set for each nozzle 5, it can be handled that there is no variation in the flying speed of the ink for each recording head 4. This makes it possible to simplify the control configuration. Further, since the recording head 4 is driven by the driving voltage value of each nozzle 5 stored in the storage unit 23 until the adjustment of the driving voltage value is performed again, the recording head 4 can be driven promptly. It becomes.

  Further, a drive voltage value for making the flying speed of the ink ejected from each nozzle 5 coincide with the target speed based on the flying speed of the ink measured by the detecting unit 19 or the area of the ink droplet calculated by the detecting unit 19 is set. Can be calculated.

  Further, by repeating the detection of the ink droplets by the detection unit 19 and the determination and setting of the drive voltage value by the control unit 22, the flying speed of the ink ejected from each nozzle 5 can be reliably matched with the target speed.

  Further, it is not necessary to adjust the driving voltage by detecting the ink flying speed of each nozzle 5 every time the power is turned on, and the recording head 4 can be driven quickly.

  Further, even when the ink temperature changes with changes in environmental conditions such as room temperature and the target speed deviates in units of the recording head 4, the ink flying speed and the dot width of each nozzle 5 are not measured each time. The target speed can be optimized quickly.

  Further, the use of the LUT can simplify the control and adjust the drive voltage quickly.

It is the schematic which shows the structure of the liquid discharge apparatus which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view illustrating a configuration of a recording head according to an embodiment of the invention. It is a perspective view which shows the structure of the speed sensor which concerns on embodiment of this invention. It is a block diagram showing the structure of the liquid discharge apparatus which concerns on embodiment of this invention. It is a block diagram showing the structure of the head drive part which concerns on embodiment of this invention. 3 is a flowchart illustrating a liquid ejection method according to an embodiment of the present invention. 5 is a flowchart illustrating a method for determining a target speed and a drive voltage value when a temperature change occurs in the recording head in the liquid ejection method according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid ejection apparatus 4 Recording head 5 Nozzle 6 Piezoelectric element 12 Temperature sensor 19 Detection part 20 Light emitting element 21 Light receiving element 22 Control part 23 Storage part 24 Input part 25 Head drive part 26 Drive waveform preparation part 27 Drive voltage setting part 28 Amplifier 29 Current buffer P Recording medium

Claims (14)

A recording head having a plurality of piezoelectric elements provided corresponding to the plurality of nozzles;
A head drive unit having a drive voltage setting unit for setting a drive voltage applied to the piezoelectric element for each of the plurality of nozzles;
An input unit for performing adjustment start input of a drive voltage value to be transmitted to the drive voltage setting unit;
A detection unit that detects ink droplets ejected from the plurality of nozzles based on a start signal from the input unit;
Based on the detection result of the detection unit, a control unit that determines a drive voltage value for matching the flying speed of the ink ejected from the plurality of nozzles with a target speed and sets the drive voltage value in the drive voltage setting unit;
A storage unit for storing the drive voltage value determined by the control unit;
A liquid ejecting apparatus comprising:   The detecting unit measures an ink flying speed by measuring a time from the start of ink ejection to ink droplet detection, and the control unit measures the ink flying speed based on the ink flying speed measured by the detecting unit. The liquid discharge apparatus according to claim 1, wherein a driving voltage value for setting the target speed to a target speed is calculated.   The detecting unit measures the flying speed of the ink by calculating the area of the detected ink droplet, and the control unit sets the flying speed of the ink to the target speed based on the flying speed of the ink measured by the detecting unit. The liquid discharge apparatus according to claim 1, wherein the driving voltage value of the liquid is calculated.   2. The ink droplet detection by the detection unit and the determination and setting of a drive voltage value by the control unit are repeated until the flying speed of ink reaches a target speed for all nozzles provided in the recording head. The liquid ejection device according to claim 3.   The controller reads a driving voltage value determined so that the flying speed of ink ejected from each nozzle from the storage unit matches a target speed when power is supplied to the liquid ejecting apparatus. The liquid ejection device according to claim 1, wherein the liquid ejection device is reset in a setting unit.   A temperature sensor for measuring the temperature of the recording head, and the control unit revises a target speed of a flying speed of ink ejected from each nozzle after a change in the temperature of the recording head based on a measurement result of the temperature sensor. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is determined.   The liquid ejecting apparatus according to claim 1, wherein the storage unit stores an LUT, and the control unit determines a drive voltage value by the LUT. A driving voltage that is provided corresponding to a plurality of nozzles in a head driving unit that drives the recording head, and that sets a driving voltage applied to the plurality of piezoelectric elements corresponding to the plurality of nozzles for each of the plurality of nozzles. An input step of performing an adjustment start input of the drive voltage value transmitted to the setting unit at the input unit;
A detection step of detecting ink droplets ejected from the plurality of nozzles in the detection unit by a start signal from the input unit;
A setting step of determining a driving voltage value for causing the flying speed of the ink ejected from the plurality of nozzles to coincide with a target speed based on the detection result of the detecting unit and setting the driving voltage value in the driving voltage setting unit. When,
A storage step of storing the drive voltage value determined by the control unit;
A liquid discharge method comprising:   In the detection step, the flying speed of the ink is measured by measuring the time from the start of ink ejection to the detection of the ink droplet, and in the setting step, the flying speed of the ink is based on the flying speed of the ink measured in the detection step. The liquid discharge method according to claim 8, wherein a driving voltage value for setting the target speed to a target speed is calculated.   In the detection step, the flying speed of the ink is measured by calculating the area of the detected ink droplet, and in the setting step, the flying speed of the ink is set to the target speed based on the flying speed of the ink measured in the detection unit. The liquid ejection method according to claim 8, wherein the driving voltage value is calculated.   9. The detection of ink droplets in the detection step and the determination and setting of drive voltage values in the setting step are repeated until the flying speed of ink reaches a target speed for all nozzles provided in the recording head. The liquid ejection method according to claim 10.   When the power is supplied to the liquid ejection device, the drive voltage value determined so that the flying speed of the ink ejected from each nozzle matches the target speed is read from the storage unit, and is read back to the drive voltage setting unit. The liquid discharging method according to claim 8, further comprising a resetting step for setting.   A head temperature measuring step of measuring the temperature of the recording head with a temperature sensor, and in the setting step, based on the measurement result of the temperature sensor, the ink discharged from each nozzle after the change of the temperature of the recording head The liquid ejection method according to any one of claims 8 to 12, wherein a target speed of the flying speed is determined again.   The LUT that associates the ink temperature with the drive voltage value is stored in the storage step, and the drive voltage value is determined by the LUT in the setting step. The liquid discharge method as described.

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