JP2009183857A - Droplet discharge device and thin film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet discharge device capable of forming a uniform thin film while suppressing variation in droplet discharge quantity due to the change of a nozzle duty. <P>SOLUTION: The droplet discharge device is provided with: a droplet discharge head 5 having a plurality of nozzles and a driving device PZ provided corresponding to each nozzle; and a drive waveform storing means 100 for storing waveform data of a drive signal supplied to each drive device PZ. The drive voltage or a drive frequency of the drive signal is set corresponding to the ratio of the nozzle to be used to total nozzle in the droplet discharge head 5 and the drive waveform storing means 100 stores the waveform data of the drive signal having the drive voltage or the drive frequency corresponding to the nozzle duty in every nozzle duty. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a droplet discharge device and a thin film forming method.

  In recent years, a thin film forming technique using a droplet discharge method (inkjet method) has been developed. Typical examples of a thin film formed by a droplet discharge method are a color filter, a light emitting layer of an organic EL panel, a metal wiring, and the like. In a thin film forming technique using a droplet discharge device, a fine liquid can be applied to a desired position in accordance with the resolution of a droplet discharge head to be used. Therefore, a fine pattern can be formed as compared with other printing techniques such as letterpress printing. For example, when a red, green, and blue color filter layer is formed on a color filter substrate, a solution containing red, green, and blue coloring materials is ejected from the micro nozzle onto the substrate, and this is dried and solidified. Thus, a color filter layer can be formed.

In this method, in order to form a uniform thin film, the amount of liquid discharged from the droplet discharge head (hereinafter referred to as discharge amount) is required to be uniform over the entire surface of the substrate. However, in a droplet discharge head having a large number of nozzles, there is a slight variation between the nozzles in the discharge characteristics (discharge amount) of the liquid material, and this variation causes a difference in the direction perpendicular to the main scanning direction. Variations in the discharge amount of the liquid material may occur, and streaky uneven density may occur in the obtained color filter. Such stripe-like shading unevenness is easy to visually recognize, and degrades the image quality of the image displayed through the color filter. In view of this, Japanese Patent Laid-Open No. 2004-228561 proposes a technique for setting an appropriate driving condition for each nozzle and compensating for discharge variation between nozzles.
JP-A-9-17483

  However, the variation in the ejection amount in the droplet ejection head is caused not only by the variation in the ejection characteristics between the nozzles but also by the change in the nozzle duty for each scan. The nozzle duty is the ratio of nozzles actually used (used nozzles / all nozzles) out of a plurality of nozzles provided in the droplet discharge head, that is, the usage rate of the nozzles. For example, when half of all nozzles are used, the nozzle duty is 50%.

  The change in the nozzle duty causes distortion of the drive waveform supplied to the nozzle. Normally, a rectangular wave or trapezoidal wave is used as the drive signal supplied to the nozzle, but when the nozzle duty increases and the drive voltage increases, overshoot or undershoot occurs at the rising or falling part of the drive voltage. As a result, the effective value of the drive voltage changes. Such a change in the effective value of the driving voltage affects the discharge amount of the liquid material, and causes film thickness unevenness. Further, when the nozzle duty changes, structural crosstalk (such as a difference in ink supply due to the use of a common ink reservoir and a physical influence between adjacent nozzles) occurs, resulting in variations in the discharge amount.

  Such a change in nozzle duty is caused by a discharge pattern (combination of nozzles to be used and nozzles not to be used) for each scan when the droplet discharge head is scanned a plurality of times within the same substrate. Caused by different things. That is, when the size, pixel size, pixel arrangement, etc. of the color filter substrate that is the discharge target are determined, the number of droplet discharge heads to be used, the number of scans, used nozzles and unused nozzles for each scan are accordingly determined. And the like are determined. Since the number of nozzles used for each scan varies depending on the pixel size, pixel arrangement, etc., the ratio of nozzles used (nozzle duty) also varies for each scan. However, in the method of Patent Document 1, such variation in the discharge amount due to the change in nozzle duty is not taken into consideration. For this reason, when the nozzle duty changes, an appropriate drive waveform cannot be supplied, and there is a problem that the discharge amount varies for each scan.

  The present invention has been made in view of such circumstances, and a droplet discharge apparatus and a thin film formation method capable of forming a uniform thin film while suppressing variations in droplet discharge amount due to a change in nozzle duty The purpose is to provide.

  In order to solve the above problems, a droplet discharge device according to the present invention includes a droplet discharge head having a plurality of nozzles and drive elements provided corresponding to the nozzles, and a waveform of a drive signal supplied to each drive element. Drive waveform storage means for storing data, and the drive condition of the drive signal is set in accordance with a nozzle duty that is a ratio of used nozzles to all nozzles in the droplet discharge head, and the drive waveform storage The means stores, for each nozzle duty, waveform data of a driving signal having a driving condition corresponding to the nozzle duty. According to this configuration, since a drive signal corresponding to the nozzle duty is supplied to each drive element, variations in droplet discharge amount due to changes in the nozzle duty are suppressed, and a uniform thin film is formed.

  In the present invention, the “driving condition” refers to the magnitude of the driving voltage applied to the driving element to perform the ejection operation, the frequency of the driving signal (driving frequency), the driving waveform (the waveform of the driving signal other than the driving voltage), etc. Say. The drive frequency refers to the number of ejection operations per unit time. The drive waveform includes, for example, the rise time of the drive voltage, the hold time of the drive voltage, the fall time of the drive voltage, the magnitude of the potential (intermediate potential) in the standby state, and the like. The discharge amount of the liquid material can be changed according to these driving conditions. This will be described in detail below.

[1] When a plurality of types of drive signals having different drive voltages are used The discharge amount of the liquid material varies depending on the magnitude of the drive voltage. When the drive voltage is large, the discharge amount is large, and when the drive voltage is small, the discharge amount is small. Therefore, the drive voltage is increased when the droplet discharge amount is small, and the drive voltage is decreased when the droplet discharge amount is large. Thereby, the discharge amount of the nozzle can be made uniform.

[2] In the case of using a plurality of types of drive signals having different drive frequencies The discharge amount of the liquid material varies depending on the frequency (drive frequency) of the drive signal. Such a change in the ejection amount due to the drive frequency is caused by the structural crosstalk of the droplet ejection head. That is, the mechanical vibration in the discharge operation of the nozzle vibrates the meniscus (liquid surface of the liquid material) and the cavity (liquid chamber) in the vicinity of the nozzle. Although the influence of the residual meniscus vibration decreases with time, when the discharge interval is shortened (that is, when the drive frequency is increased), the next discharge operation is performed before the vibration of the meniscus and the cavity is sufficiently reduced. The vibration of the meniscus and the cavity affects the next discharge operation. For this reason, when the drive frequency is low, the discharge amount hardly changes. However, when the drive frequency is high, a periodic fluctuation that repeatedly increases and decreases the discharge amount as the drive frequency increases is shown. Therefore, the discharge amount of the liquid material can be adjusted by controlling the drive frequency based on this fluctuation curve.

  In the present invention, it is possible to adjust the discharge amount of the liquid material by positively utilizing such a change in the discharge amount due to the drive frequency. For example, when the droplet discharge amount is small, driving is performed at the driving frequency of the peak portion of the fluctuation curve. Conversely, when the droplet discharge amount is large, driving is performed at the driving frequency in the valley portion of the fluctuation curve. Thereby, the discharge amount of the nozzle can be made uniform.

[3] Using a plurality of types of drive signals having different drive waveforms The discharge amount of the liquid material varies depending on the drive waveform (the waveform of the drive signal other than the drive voltage). Such a change in the discharge amount due to the drive waveform is caused by the vibration behavior of the meniscus (liquid surface of the liquid) near the nozzle and the cavity. For example, the discharge operation of the droplet discharge head will be described in three states: a standby state (intermediate potential), a charged state (high potential), and a discharged state (low potential). In this case, during the period from the standby state to the charged state (rising period of the drive voltage), the volume of the cavity adjacent to the nozzle increases, and the liquid material is supplied into the cavity. During the period from the charge state to the discharge state (falling period of the drive voltage), the volume of the cavity decreases and the liquid material is discharged to the outside through the nozzle.

  During the period from the standby state to the charged state, the meniscus position moves to the cavity side due to the increase in the volume of the cavity, but the supply of the liquid material from the liquid material supply side also increases. This is because the shorter the rise time, the more vigorous the liquid is drawn from the meniscus and liquid supply side. Therefore, if the rise time is shortened, the liquid material is drawn largely to the cavity side, and the operation is quickly shifted to the discharge operation as it is, the discharge amount of the liquid material increases as much as the liquid material is drawn. On the contrary, when the rising time is lengthened and the liquid material is drawn to the cavity side to a small extent, the discharge amount of the liquid material is reduced by the amount of the liquid material being drawn.

  The potential in the standby state (intermediate potential) affects the amount of movement of the meniscus. For example, when the potential in the standby state is brought close to the potential in the charged state and the potential difference between the standby state and the filling state is reduced, the meniscus hardly moves even if the rise time is shortened. For this reason, even if the discharge operation is quickly performed, the discharge amount of the liquid material hardly changes. On the other hand, when the potential in the standby state is brought close to the potential in the discharge state and the potential difference between the standby state and the charged state is increased, the amount of movement of the meniscus increases. In this state, the discharge is started and the discharge amount is reduced.

  The meniscus drawn to the cavity side attempts to return to the original position (standby position) when the cavity capacity variation ends. Therefore, in the charged state, the meniscus vibrates with reference to the original position. For this reason, when the meniscus moves to the discharge operation at the timing when the meniscus vibrates toward the cavity, the discharge amount is reduced by the amount of the meniscus being drawn. On the contrary, when the operation moves to the discharge operation at the timing when the meniscus vibrates on the side opposite to the cavity, the discharge amount increases by the amount that the meniscus protrudes to the outside. The timing at which ejection is performed varies depending on the charge state holding time. When the holding time is taken on the horizontal axis and the discharge amount is taken on the vertical axis, the discharge amount shows a periodic fluctuation that repeatedly increases and decreases as the holding time increases. Therefore, the discharge amount of the liquid material can be adjusted by controlling the holding time based on the fluctuation curve.

  On the other hand, the falling period of the drive voltage affects the pressure applied when the liquid is pushed out of the nozzle. When the fall time of the drive voltage is short, the applied pressure becomes large, and when the fall time is long, the applied pressure becomes small. When the applied pressure is large, the liquid material vigorously jumps out of the nozzle, so that the discharge amount increases accordingly. Conversely, when the applied pressure is small, the liquid material is pushed out slowly, so that the discharge amount is reduced.

  In the present invention, it is possible to adjust the discharge amount of the liquid material by positively utilizing the variation in the discharge amount due to the vibration behavior of the meniscus and the cavity. For example, when the droplet discharge amount is small, one of the rising time, holding time, falling time, or intermediate potential of the drive voltage is controlled to increase the discharge amount. Conversely, when the droplet discharge amount is large, one of the drive voltage rise time, hold time, fall time, and intermediate potential is controlled to reduce the discharge amount. Thereby, the discharge amount of the nozzle can be made uniform.

  In the present invention, for each drive element, drive signal selection means for selecting and supplying one drive signal from a plurality of types of drive signals, the drive element and the type of drive signal supplied to the drive element, A plurality of types of drive signal waveform data corresponding to the nozzle duty is obtained from the drawing data storage means for storing the drive signal selection data indicating the correspondence between the nozzle duty and the drive waveform storage means. Drive signal generation means for generating the plurality of types of drive signals based on the waveform data, wherein the drive signal selection means is based on the drive signal selection data stored in the drawing data storage means Preferably, the type of drive signal supplied to each drive element is selected from the drive signals generated by the drive signal generation means. According to this configuration, it is possible to freely add, delete, and change drive signal selection data and drive signal waveform data, thereby facilitating data management. In addition, when droplets are actually ejected onto a liquid ejection object, necessary drive signal selection data and drive signal waveform data can be obtained immediately in accordance with the ejection pattern (nozzle duty) of the ejection object. Therefore, it can contribute to the speeding up of the discharge process.

  In the present invention, a plurality of the drive signal generation means are provided for the droplet discharge head, and the drive signal selection means reads the drive signal selection data from the drawing data storage means and performs the drive For each element, one drive signal is selected and supplied from among the drive signals generated by the plurality of drive signal generation means, and the number of the drive signal generation means is provided in the droplet discharge head. Desirably less than the number of nozzles. According to this configuration, it is possible to suppress the variation in the droplet discharge amount to a level that is not visually recognized by the user as a non-uniformity while minimizing an increase in the number of parts and an increase in apparatus cost. The number of drive signal generation means may be about four, for example, and it has been clarified by the present inventors that a sufficient effect can be obtained.

  In the present invention, the drawing data storage means outputs discharge data indicating a correspondence relationship between the drive element and information defining whether or not to supply a drive signal to the drive element to a nozzle used in the droplet discharge head. Supply switching means for storing the discharge pattern corresponding to a combination with an unused nozzle and switching supply or non-supply of the drive signal selected by the drive signal selection means for each of the drive elements based on the discharge data It is desirable to provide. According to this configuration, similarly to the drive signal selection data, it becomes easy to manage the discharge data, and necessary discharge data can be obtained immediately according to the discharge pattern of the discharge target, so the discharge process can be speeded up. Can contribute.

  In the present invention, the drive signal selection unit and the supply switching unit are provided in the droplet discharge head, and a drive circuit board on which the drawing data storage unit, the drive waveform storage unit, and the drive signal generation unit are provided is provided. It is desirable. According to this configuration, replacement of the droplet discharge head, replacement of the drive circuit board, replacement of used parts, and the like can be facilitated, and maintenance can be improved.

  In the present invention, it is preferable that the drive signal selection data is set so that the droplet discharge amount of each nozzle is made uniform. According to this configuration, the variation in the droplet discharge amount due to the variation in the discharge characteristics of each nozzle is reduced, and the occurrence of unevenness can be prevented.

  In the present invention, the drive element is preferably a piezoelectric element. According to this configuration, an amount of liquid droplets corresponding to the drive signal can be ejected with high accuracy.

  A thin film forming method of the present invention includes a step of discharging a liquid material from a nozzle of the droplet discharge head onto the substrate while relatively moving a droplet discharge head having a plurality of nozzles and the substrate. The nozzles are ejected by drive signals having different drive conditions (drive voltage, drive frequency, drive waveform, etc.) according to the nozzle duty, which is the ratio of the used nozzles to all the nozzles of the droplet discharge head. It is characterized by that. According to this method, since a drive signal corresponding to the nozzle duty is supplied to the droplet ejection head, variations in the droplet ejection amount due to a change in the nozzle duty can be suppressed, and a uniform thin film can be formed.

  In the present invention, the plurality of nozzles are classified into a plurality of groups in consideration of the ejection characteristics of the nozzles, and ejection is performed by different drive signals for each group, and a combination of drive signals supplied to each group includes It is desirable to design for each nozzle duty. According to this method, it is possible to determine (calculate) stepwise appropriate conditions by grasping the distribution of discharge amounts in units of groups, and further to select appropriate conditions for each nozzle, so driving according to the discharge characteristics of the nozzles The signal can be set with high accuracy.

  In the present invention, it is desirable that each of the plurality of groups is constituted by a substantially equal number of nozzles. According to this method, significant concentration of nozzles corresponding to a specific condition can be prevented. The number of nozzles constituting each group is not limited to the above-described mode, but the drive voltage is set according to the group unit, so that the number of nozzles constituting each group is made substantially equal. Thus, an imbalance in the number of nozzles corresponding to each appropriate drive voltage can be made difficult to occur. Since the corresponding number of nozzles at each appropriate driving voltage affects the distortion of the driving signal and the like, it is desirable to prevent an imbalance between the appropriate driving voltages as much as possible.

  Hereinafter, an embodiment of a droplet discharge device and a driving method thereof according to the present invention will be described with reference to the drawings. In the following description, the XYZ rectangular coordinate system shown in FIG. 1 is set, and each member will be described with reference to this XYZ rectangular coordinate system. The XYZ orthogonal coordinate system is set so that the X axis and the Y axis are parallel to the work stage 2, and the Z axis is set in a direction orthogonal to the work stage 2. In the XYZ coordinate system in FIG. 1, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z axis is set to the vertically upward direction.

  FIG. 1 is a schematic configuration diagram of a droplet discharge device IJ of the present embodiment. The droplet discharge device IJ is a device that forms a color filter layer by discharging droplets of a color filter material onto a color filter substrate (discharge target) by, for example, an inkjet method.

  The droplet discharge device IJ includes an apparatus base 1, a work stage 2, a stage moving device 3, a carriage 4, a droplet discharge head 5, a carriage moving device 6, a tube 7, a first tank 8, a second tank 9, and a third tank. 10 and a control device 11.

  The device mount 1 is a support for the work stage 2 and the stage moving device 3. The work stage 2 is installed on the apparatus base 1 so as to be movable in the X-axis direction by the stage moving device 3, and the color filter substrate P transported from the upstream transport device (not shown) is transferred to the vacuum suction mechanism. Is held on the XY plane. The stage moving device 3 includes a bearing mechanism such as a ball screw or a linear guide, and moves the work stage 2 in the X-axis direction based on a stage position control signal indicating the X coordinate of the work stage 2 input from the control device 11. Let

  The carriage 4 holds the droplet discharge head 5 and is provided so as to be movable in the Y-axis direction and the Z-axis direction by the carriage moving device 6. The droplet discharge head 5 includes a plurality of nozzles (not shown), and discharges droplets of the color filter material based on drawing data and drive control signals input from the control device 11. The droplet discharge heads 5 are provided corresponding to the color filter materials R (red), G (green), and B (blue). Each droplet discharge head 5 is connected to a tube 7 via a carriage 4. It is connected with. Then, the droplet discharge head 5 corresponding to R (red) is supplied with the color filter material for R (red) from the first tank 8 via the tube 7, and the droplet discharge head corresponding to G (green). 5 is supplied with a color filter material for G (green) from the second tank 9 via the tube 7, and the droplet discharge head 5 corresponding to B (blue) is supplied to the third tank 10 via the tube 7. Is supplied with a color filter material for B (blue).

  The carriage moving device 6 has a bridge structure straddling the device mount 1, and includes a bearing mechanism such as a ball screw or a linear guide in the Y-axis direction and the Z-axis direction, and is input from the control device 11. Based on the carriage position control signal indicating the Y coordinate and the Z coordinate, the carriage 4 is moved in the Y axis direction and the Z axis direction.

  The tube 7 is a color filter material supply tube that connects the first tank 8, the second tank 9, the third tank 10 and the carriage 4 (droplet discharge head 5). The first tank 8 stores the color filter material for R (red) and supplies the color filter material to the droplet discharge head 5 corresponding to R (red) via the tube 7. The second tank 9 stores the color filter material for G (green) and supplies the color filter material to the droplet discharge head 5 corresponding to G (green) via the tube 7. The third tank 10 stores the color filter material for B (blue) and supplies the color filter material to the droplet discharge head 5 corresponding to B (blue) via the tube 7.

  The control device 11 outputs a stage position control signal to the stage moving device 3, outputs a carriage position control signal to the carriage moving device 6, and outputs drawing data and a drive control signal to the drive circuit board 30 of the droplet discharge head 5. By outputting and performing synchronous control of the droplet discharge operation by the droplet discharge head 5, the positioning operation of the color filter substrate P by the movement of the work stage 2, and the positioning operation of the droplet discharge head 5 by the movement of the carriage 4, A droplet of the color filter material is discharged to a predetermined position on the color filter substrate P.

  FIG. 2 is a schematic configuration diagram of the droplet discharge head 5. 2A is a plan view of the droplet discharge head 5 viewed from the work stage 2 side, FIG. 2B is a partial perspective view of the droplet discharge head 5, and FIG. It is a fragmentary sectional view for 1 nozzle.

As shown in FIG. 2A, the droplet discharge head 5 includes a plurality of (for example, 180) nozzles N _{1 to} N ₁₈₀ arranged in the Y-axis direction. Although FIG. 2A shows one row of nozzles, the number of nozzles provided in the droplet discharge head 5 can be arbitrarily changed, and one row of nozzles arranged in the Y-axis direction includes a plurality of rows in the X-axis direction. It may be provided. Further, the number of droplet discharge heads 5 arranged in the carriage 4 can be arbitrarily changed. Further, a plurality of carriages 4 may be provided for each sub-carriage.

As shown in FIG. 2B, the droplet discharge head 5 includes a vibration plate 20 provided with a material supply hole 20 a connected to the tube 7, and a nozzle plate 21 provided with nozzles N _{1 to} N _180. A liquid reservoir 22 provided between the vibration plate 20 and the nozzle plate 21, a plurality of partition walls 23, and a plurality of cavities (liquid chambers) 24 are provided. On the vibration plate 20, piezoelectric elements (drive elements) PZ _{1 to} PZ ₁₈₀ are arranged corresponding to the nozzles N _{1 to} N ₁₈₀ . The piezoelectric elements PZ _{1 to} PZ ₁₈₀ are, for example, piezoelectric elements.

The liquid reservoir 22 is filled with a liquid color filter material (liquid material) supplied through the material supply hole 20a. Cavity 24, the diaphragm 20, the nozzle plate 21, which is formed so as to be surrounded by a pair of partition walls 23 are provided in one-to-one correspondence to the nozzles _N 1 _{to N 180.} Further, a color filter material is introduced into each cavity 24 from the liquid reservoir 22 via a supply port 24 a provided between the pair of partition walls 23.

As shown in FIG. 2C, the piezoelectric element PZ ₁ has a piezoelectric material 25 sandwiched between a pair of electrodes 26, and is configured such that when a drive signal is applied to the pair of electrodes 26, the piezoelectric material 25 contracts. It is a thing. The diaphragm 20 on which such a piezoelectric element PZ ₁ is disposed is integrally bent with the piezoelectric element PZ ₁ and bends outward (opposite the cavity 24) at the same time. The volume of 24 is increased. Accordingly, the color filter material corresponding to the increased volume in the cavity 24 flows from the liquid reservoir 22 through the supply port 24a. Further, when the application of the drive signal to the piezoelectric element PZ ₁ is stopped from such a state, the piezoelectric element PZ ₁ and the diaphragm 20 both return to the original shape, and the cavity 24 also returns to the original volume. the pressure of the color filter material is increased in the inner, the droplet L of the color filter material is ejected toward the nozzle N ₁ on the color filter substrate P.

  FIG. 3 is an explanatory diagram of a method for forming a color filter on the color filter substrate P using the droplet discharge head 5. FIG. 3A is a schematic plan view of a color filter substrate P that is a liquid discharge target. FIG. 3B is a partially enlarged plan view of the color filter substrate P.

  In FIG. 3A, a plurality of panel regions CA are set on the surface of a large area color filter substrate P formed of glass, plastic or the like. Each panel area CA is separated (cut) from each other and provided as an individual color filter substrate. As shown in FIG. 3B, a plurality of pixels PX arranged in a dot shape are provided inside each panel area CA. The pixels PX are arranged in a matrix in each panel area CA, and a color filter layer CF is formed for each pixel PX.

In the present embodiment, FIG. 3 (b) illustrates the vertical direction (the direction indicated by arrow A ₁ and arrow A ₂₎ as the main scanning direction, a direction (lateral direction) perpendicular to the main scanning direction as the sub-scanning direction, The droplet discharge head 5 is disposed on the color filter substrate P. A liquid material containing a coloring material from the plurality of nozzles N of the droplet discharge head 5 while moving (scanning) the color filter substrate P relative to the droplet discharge head 5 in the main scanning direction and the sub-scanning direction. (Color filter material) is discharged, and a color filter layer CF is formed on each pixel PX on the color filter substrate P.

  The droplet discharge head 5 is scanned a plurality of times for one panel area CA. For example, after the droplet discharge head 5 is scanned in the main scanning direction, the droplet discharge head 5 is moved (scanned) in the sub-scanning direction, and scanning is performed again in the main scanning direction. When one panel area CA moves from the left end to the right end (sub-scanning), it returns to the left end of the panel area CA again, and scans in the main scanning direction at a position slightly different from the position where ejection has already been performed. Then, by performing such scanning a plurality of times, the color filter layer CF having a desired film thickness is formed on all the pixels PX in the panel area CA.

  In FIG. 3B, the reason why the droplet discharge head 5 is inclined with respect to the sub-scanning direction is to match the pitch of the nozzles N of the droplet discharge head 5 with the pitch of the pixels PX. If the pitch of the nozzles N and the pitch of the pixels PX are set so as to satisfy a predetermined correspondence relationship, it is not necessary to tilt the droplet discharge head 5 obliquely.

  The color filter layer CF is formed by arranging R (red), G (green), and B (blue) colors in an appropriate arrangement form such as a so-called stripe arrangement, delta arrangement, mosaic arrangement, or the like. Therefore, in the liquid discharge step shown in FIG. 3B, the droplet discharge heads 5 for discharging the R, G, and B color filter materials are prepared in advance for the three colors R, G, and B. Then, an array of three color filter layers CF of R, G, and B is formed on one color filter substrate P using these droplet discharge heads 5 in order.

<Circuit Configuration of First Embodiment>
FIG. 4 is an explanatory diagram of a circuit configuration of the first embodiment of the droplet discharge device IJ. The droplet discharge apparatus IJ according to this embodiment includes a control computer (control unit) 100 that performs overall control of the entire apparatus, and a control that is connected to the control computer 100 and performs electrical drive control of the droplet discharge head 5. Circuit board 101. The control device 11 shown in FIG. 1 includes some or all of the functions of the control computer 100 and the control circuit board 101.

  The control computer 100 exchanges data with an internal memory such as a CPU (Central Processing Unit), a hard disk, a ROM (Read Only Memory) and a RAM (Random Access Memory), a droplet discharge head 5, a carriage moving device 6 and the like. Various input / output interface circuits and the like are provided.

  The control circuit board 101 is electrically connected to the piezoelectric element PZ provided in the droplet discharge head 5 via the flexible cable 102. The droplet discharge head 5 includes a shift register (SL) 103, a latch circuit (LAT) 104, a level shifter (LS) 105, and a switch (SW) 106 corresponding to the piezoelectric element PZ provided for each nozzle N. Are provided.

  The discharge control of the droplet discharge device IJ is performed as follows. First, the control computer 100 stores in advance dot pattern data obtained by converting the arrangement pattern of the liquid material for each panel region on the substrate P into data. The dot pattern data is transmitted to the control circuit board 101. The control circuit board 101 decodes the dot pattern data to generate nozzle data that is ON / OFF (discharge / non-discharge) information for each nozzle N. The nozzle data is converted into a serial signal (SI) and transmitted to each shift register 103 in synchronization with the clock signal (CK).

  The nozzle data transmitted to the shift register 103 is latched at a timing when a latch signal (LAT) is input to the latch circuit 104, and further converted into a gate signal for the switch 106 by the level shifter 105. That is, when the nozzle data is ON, the switch 106 is opened and a drive signal (COM) including a drive waveform corresponding to the discharge amount of the liquid material is supplied to the piezoelectric element PZ, and when the nozzle data is OFF, The switch 106 is closed and the drive signal (COM) is not supplied to the piezoelectric element PZ. Then, from the nozzle N corresponding to ON, the piezoelectric element PZ is driven with the supplied drive waveform, whereby the liquid material is discharged as droplets, and the discharged liquid material is provided on the substrate P. Placed on the designated panel area.

  In the present embodiment, the control computer 100 prepares and stores in advance two or more different drive conditions as drive signals to be applied to the piezoelectric element PZ. For example, a drive signal having a different drive voltage, a drive signal having a different drive frequency, a drive signal having a different drive waveform (a waveform of a drive signal other than the drive voltage), or a combination of two or more of these drive conditions Drive signals having different drive conditions are prepared and stored.

  Further, in this embodiment, when a plurality of drive signals having different drive conditions are stored in this way, it is determined and stored at which timing and which drive condition is applied to each nozzle N. That is, when the dot pattern data obtained by converting the liquid material arrangement pattern for each panel area is stored, the relationship between the position of the panel area in the main scanning direction and the drive signal (driving condition) applied to the piezoelectric element PZ is also included. Remember.

  Then, one drive signal is selected from a plurality of types of drive signals having different drive conditions and supplied to each of the plurality of piezoelectric elements PZ. In this case, the criterion for selection is a droplet discharge pattern or a nozzle duty. That is, as shown in FIG. 2, when the liquid droplet ejection head 5 scans the color filter substrate P a plurality of times to discharge the liquid material to a plurality of locations on the color filter substrate P, generally, every one scan. The discharge pattern is different. Here, the ejection pattern refers to a combination of a nozzle N to be used and a nozzle N to be unused among a plurality of nozzles N provided in one droplet ejection head 5. The reason why the ejection pattern is different for each scan is that when the droplet ejection head 5 moves in the sub-scanning direction, the spatial arrangement of the nozzles N and the pixels PX shifts.

  When the size of the color filter substrate P, the size of the pixel PX, the arrangement of the pixels PX, and the like are determined, the number of droplet discharge heads 5 to be used, the number of scans, and the nozzles used for each scan are determined accordingly. A combination (discharge pattern) of N and the unused nozzle N is determined. Since the number of used nozzles N for each scan varies depending on the size of the pixel PX, the arrangement of the pixels PX, and the like, the ratio of used nozzles N (used nozzles / all nozzles), that is, the nozzle duty also changes for each scan. When the nozzle duty changes, an overshoot or undershoot occurs in the drive waveform supplied to the nozzle N, causing variations in the discharge amount. Further, when the nozzle duty changes, structural crosstalk (ink supply difference due to the use of a common ink reservoir, physical influence between adjacent nozzles, etc.) occurs, and variations in ejection amount occur.

  For example, FIG. 5 is an explanatory diagram of a variation distribution of droplet discharge amounts when discharging is performed using three types of discharge patterns (pattern A, pattern B, and pattern C) having different nozzle duties (discharge patterns). In FIG. 5, the horizontal axis represents the nozzle number, and the vertical axis represents the droplet discharge amount (weight). Symbols a, b, and c indicate distributions of variations in the droplet discharge amount when discharge is performed in the patterns A, B, and C, respectively.

In addition, due to the characteristics of the droplet discharge head 5, the variation in droplet discharge amount is very large in the nozzles at both ends (nozzles N _{1 to} N ₉ and nozzles N _{171 to} N ₁₈₀ ). is doing. Even when the droplet discharge head 5 is actually used, 160 nozzles N _{10 to} N _{170 out} of 180 nozzles are used.

In pattern B and pattern C, the nozzle duty decreases in the order of pattern A, pattern B, and pattern C. Therefore, a large drive waveform distortion occurs in the pattern A, and the smallest drive waveform distortion occurs in the pattern C. As a result, the average droplet discharge amount of each of the nozzles N _{10 to} N ₁₇₀ decreases in the order of pattern A, pattern B, and pattern C. Such variation in the discharge amount varies depending on the size of the nozzle duty. When the variation of the nozzle duty is large, the variation in the discharge amount between the patterns may be a size that cannot be ignored.

  Therefore, in this embodiment, the driving condition of the driving signal supplied to the piezoelectric element PZ of each nozzle N is selected for each scan so that the droplet discharge amount approaches a preset design value (appropriate weight). I have to. The drive signal of the selected drive condition is applied in common to all the nozzles N of the droplet discharge head 5. The control computer 100 selects an appropriate driving condition according to the nozzle duty of the droplet discharge head 5 and suppresses variations in the discharge amount for each scan. Hereinafter, a specific method of selecting conditions will be described.

[1] When Using Multiple Types of Drive Signals with Different Drive Voltages FIG. 6 is a graph showing the relationship between the drive voltage and the droplet discharge amount (ink weight). The droplet discharge amount varies depending on the magnitude of the drive voltage. When the drive voltage is large, the discharge amount is large, and when the drive voltage is small, the discharge amount is small. Therefore, when the droplet discharge amount is smaller than the appropriate weight, the drive voltage is increased, and when the droplet discharge amount is larger than the proper weight, the drive voltage is decreased. Thereby, the discharge amount of the nozzle N can be brought close to an appropriate weight.

[2] When Using Multiple Types of Drive Signals with Different Drive Frequency FIG. 7 is a graph showing the relationship between the drive frequency and the droplet discharge amount (ink weight). The droplet discharge amount varies depending on the driving frequency. It is considered that the change in the ejection amount due to the drive frequency is caused by the structural crosstalk of the droplet ejection head 5. That is, the mechanical vibration in the discharge operation of the nozzle N vibrates the meniscus (liquid surface of the liquid material) and the cavity near the nozzle. Although the influence of the residual meniscus vibration decreases with time, when the discharge interval is shortened (that is, when the drive frequency is increased), the next discharge operation is performed before the meniscus vibration is sufficiently suppressed. The vibration of the cavity affects the next discharge operation. For this reason, when the drive frequency is low, the discharge amount hardly changes. However, when the drive frequency is high, a periodic fluctuation that repeatedly increases and decreases the discharge amount as the drive frequency increases is shown. Therefore, the discharge amount of the liquid material can be adjusted by controlling the drive frequency based on this fluctuation curve.

In the present embodiment, the discharge amount of the liquid material can be adjusted by positively utilizing such a change in the discharge amount due to the drive frequency. For example, if the droplet ejection volume is less than the appropriate weight is driven at a driving frequency F ₂ of the mountain portion of the variation curve. Conversely, if the droplet ejection volume is greater than the proper weight is driven by the driving frequencies F ₁ of the valley portion of the variation curve. Thereby, the discharge amount of the nozzle N can be brought close to an appropriate weight.

  FIG. 8 is an explanatory diagram in the case of performing ejection by changing the drive frequency. FIG. 8A is an explanatory diagram of a driving method when the ejection amount increases due to a change in nozzle duty, and FIG. 8B is an explanatory diagram of a driving method when the ejection amount decreases due to a change in nozzle duty. is there.

In FIG. 8A, while the droplet discharge head 5 is scanned in the vertical direction (main scanning direction), four droplets of liquid L are discharged from each nozzle N into one pixel PX at a discharge interval P1. Discharge interval P1 corresponds to the driving frequencies F ₁ of the variation curve of FIG. On the other hand, in FIG. 8B, while the droplet discharge head 5 is scanned in the vertical direction (main scanning direction), four droplets of liquid L are discharged from each nozzle N into one pixel PX at a discharge interval P2. The Discharge interval P2 corresponds to the driving frequency F ₂ of the variation curve of FIG.

In any case, the amount of the liquid ejected into one pixel PX is 4 drops. Since the discharge amount per droplet increases when the discharge amount increases due to the change in the nozzle duty in FIG. 8A, and the discharge amount decreases due to the change in the nozzle duty in FIG. 8B, FIG. Is larger than FIG. 8B. However, the drive in Figure 8 (a) in which is driven by the driving frequencies F ₁ corresponding to the valleys of the variation curve of FIG. 6, and FIG. 8 (b) the driving frequency F ₂ corresponding to the mountain of the variation curve of FIG. 7 Has been. Therefore, the discharge amount per drop of both is substantially equal. Accordingly, the discharge amount of the liquid material discharged into one pixel PX is equal in both, and a color filter layer having a uniform film thickness is formed.

[3] When Using Plural Types of Drive Signals with Different Drive Waveforms FIGS. 9 to 12 illustrate the relationship between the profile of the drive signal applied to the piezoelectric element PZ and the discharge amount of the liquid material discharged from the nozzle N. FIG. 9A shows the state of the cavity 24 in the standby state (intermediate potential V _M ), FIG. 9B shows the state of the cavity 24 in the charged state (high potential V _H ), and FIG. 9C shows the state of the discharged state (low potential V _L ). Each is shown. FIG. 9D shows the waveform of the drive signal applied to the piezoelectric element PZ. FIG. 10 shows the relationship between the drive waveform and the droplet discharge amount. 11, FIG. 12 is a schematic diagram showing a meniscus behavior when changing the potential V _M of the standby state.

Note that, in FIGS. 9 to 12, the sign V _M voltage in the standby state (intermediate potential), the V _H represents the potential of the state of charge, V _L is the potential of the discharge state, respectively. The drive voltage is defined by the potential difference between the high potential _VH and the low potential _VL . Moreover, (the rise time of the drive voltage) time code t ₁ until the charge state from the standby state, (retention time of the drive voltage) code t ₂ is the time for holding the charging state, the code t ₃ until discharged state from the charged state (Time for driving voltage fall) is shown.

The discharge amount of the liquid varies depending on the drive waveform. The change in the discharge amount due to the drive waveform is caused by the vibration behavior of the meniscus (liquid surface of the liquid material) near the nozzle N and the cavity. For example, as shown in FIG. 9, the discharge operation of the droplet discharge head 5 will be described in three states: a standby state, a charge state, and a discharge state. In this case, during the period t ₁ from the standby state to the charged state, the volume of the cavity 24 adjacent to the nozzle N increases and the liquid material is supplied into the cavity 24. During a period t ₃ from the charged state to the discharged state, the volume of the cavity 24 decreases and the liquid material is discharged to the outside through the nozzle N.

In the period t ₁ from the standby state to the charged state, the meniscus position also moves toward the cavity 24 due to the increase in the volume of the cavity 24, and the amount of movement increases as the rise time t ₁ decreases. This is because the shorter the rise time t ₁ , the stronger the liquid is drawn from the meniscus and liquid supply side. Therefore, to shorten the rising time t _1, greatly drawn the liquid material to the cavity 24 side, Turning to it quickly discharge operation, the discharge amount of the liquid is increased by more minute pressed amount of the liquid. Conversely, a longer rise time t _1, when the retract reduce the liquid material to the cavity 24 side, the discharge amount of the liquid only a small amount the pull-in amount of the liquid is reduced. FIG. 10A shows the relationship between the rise time t ₁ and the discharge amount I _W.

The standby state potential V _M (intermediate potential) affects the amount of movement of the meniscus. For example, as shown in FIG. 11, closer to the potential V _M of the standby state to the potential V _H of the charge state, when the small potential difference V _HM the filling state and the standby state is to shorten the rise time t ₁ However, the movement of the meniscus hardly occurs. For this reason, even if the operation quickly moves, the discharge amount of the liquid L is hardly changed. On the other hand, as shown in FIG. 12, closer to the potential V _M of the standby state to the potential V _L of the discharge state, when a large potential difference V _HM the charge state and the standby state, the amount of movement of the meniscus is increased When the discharge operation is quickly performed, the discharge is started in a state where the meniscus is drawn, and the discharge amount is reduced. FIG. 10 (b) shows the relationship between such an intermediate potential _{V M} and the ejection amount _{I W.}

The meniscus drawn into the cavity 24 side tries to return to the original position (position in the standby state) when the capacity variation of the cavity 24 is completed. Therefore, in the charged state, the meniscus vibrates with reference to the original position. For this reason, when the meniscus moves to the discharge operation at the timing when the meniscus vibrates toward the cavity 24, the discharge amount is reduced by the amount the meniscus is drawn. On the contrary, when the operation moves to the discharge operation at the timing when the meniscus vibrates on the side opposite to the cavity 24, the discharge amount increases by the amount that the meniscus protrudes greatly to the outside. Which timing ejection is performed is changed by the holding time t ₂ in a charged state. As shown in FIG. 10 (c), the holding time t ₂ the horizontal axis, taking the discharge amount I _W on the vertical axis, the discharge amount I _W is periodic repeating increase and decrease with increasing holding time t ₂ Showing fluctuations. Thus, by controlling the holding time t ₂ based on the variation curve, it is possible to adjust the discharge amount I _W of the liquid.

On the other hand, the period t ₃ fall affects the pressure at which the pushing to the outside the liquid material from the nozzle N. When the fall time t ₃ shorter, pressure is increased, when the fall time t ₃ long, pressure is reduced. When the applied pressure is large, the liquid material jumps out of the nozzle N vigorously, and the discharge amount increases accordingly. On the contrary, when the applied pressure is small, the liquid material is pushed out slowly, so that the discharge amount decreases accordingly. FIG. 10D shows the relationship between the fall time t ₃ and the discharge amount I _W.

In the present embodiment, the discharge amount of the liquid material is corrected by positively utilizing the variation in the discharge amount due to the vibration behavior of the meniscus and the cavity. That is, when the discharge amount increases or decreases due to the change in nozzle duty, the drive voltage rise time t ₁ , holding time t ₂ , fall time t ₃ , intermediate potential for all nozzles N in the droplet discharge head 5. one of V _M, or by controlling the respective dimensions, increases or decreases the discharge rate. As a result, a constant discharge amount can always be obtained regardless of the change in nozzle duty.

<Circuit Configuration of Second Embodiment>
Next, the circuit configuration of the second embodiment of the droplet discharge device IJ will be described. FIG. 13 is a circuit configuration diagram of the droplet discharge head 5 and a drive circuit board 30 for supplying a drive signal to the droplet discharge head 5. In the present embodiment, the same reference numerals are assigned to configurations common to the first embodiment, and detailed description thereof is omitted.

The drive circuit board 30 of the present embodiment is connected to the control device 11 shown in FIG. 1 by a PCI bus, and based on drawing data and drive control signals input from the control device 11, the piezoelectric elements PZ ₁ to PZ ₁ . Selection of a drive signal to be applied to the PZ ₁₈₀ , generation of a drive signal, control of ejection timing, and the like are performed. In the droplet discharge device of the present embodiment, one drive circuit substrate 30 is provided for one droplet discharge head 5, but each of R (red), G (green), and B (blue) is provided. Since the corresponding droplet discharge head 5 and the drive circuit substrate 30 have the same configuration, the following description will be given using one droplet discharge head 5 and the drive circuit substrate 30 for convenience.

The drive circuit board 30 includes an interface 31, a drawing data memory 32, an address conversion circuit 33, a first drive waveform memory 34, a second drive waveform memory 35, a first D / A converter 36, and a second D / A. A converter 37, a third D / A converter 38, and a fourth D / A converter 39 are provided. The droplet discharge head 5 includes a COM selection circuit 40, a switching circuit 50, and a piezoelectric element group 60 including piezoelectric elements PZ _{1 to} PZ ₁₈₀ . The piezoelectric elements PZ _{1 to} PZ ₁₈₀ can be labeled as capacitors as shown in FIG.

  The drawing data memory 32 corresponds to drawing data storage means in the present invention, and the first drive waveform memory 34 and the second drive waveform memory 35 correspond to drive waveform storage means in the present invention, and the first D / D The A converter 36, the second D / A converter 37, the third D / A converter 38, and the fourth D / A converter 39 correspond to drive signal generating means in the present invention. The COM selection circuit 40 corresponds to drive signal selection means in the present invention, and the switching circuit 50 corresponds to supply switching means in the present invention.

  The control device 11 (see FIG. 1) and the interface 31 of the drive circuit board 30 are connected by a PCI bus (not shown), and the drawing data SI and the clock signal CLK as a drive control signal are transmitted from the control device 11 via the PCI bus. , Latch signal LT, DAC clock signals CLK1 and CLK2, drawing data address signal AD1, drawing data write enable signal WE1, drive waveform data signal WD, waveform data address signal AD2, waveform data write enable signal WE2, chip selector signals CS1 and CS2 The output enable signals OE1 and OE2 are output to the interface 31.

  The interface 31 outputs the drawing data SI, the drawing data write enable signal WE1, the drawing data address signal AD1, the chip selector signal CS1, and the output enable signal OE1 to the drawing data memory 32. The interface 31 outputs the clock signal CLK and the latch signal LT to the COM selection circuit 40 and the switching circuit 50 of the droplet discharge head 5. The interface 31 outputs the DAC clock signal CLK1 to the first D / A converter 36 and the third D / A converter 38, and outputs the DAC clock signal CLK2 to the second D / A converter 37 and the fourth D / A. Output to the converter 39. The interface 31 sends the waveform data write enable signal WE2, the waveform data address signal AD2, the drive waveform data signal WD, the chip selector signal CS2, and the output enable signal OE2 to the first drive waveform memory 34 and the second drive waveform memory 35. Output.

The drawing data memory 32 is, for example, a 32-bit SRAM, and when data writing is requested by the drawing data write enable signal WE1, the chip selector signal CS1, and the output enable signal OE1, an address designated by the drawing data address signal AD1. Stores the drawing data SI. Here, the drawing data SI includes ejection data SIA and COM selection data SIB (drive signal selection data). Discharge data SIA is a pixel pattern formed on the color filter substrate P divided into a matrix, and binary data defining whether or not to discharge droplets is mapped for each dot constituting the matrix. Bitmap data. Dot pitch of the matrix in the Y-axis direction corresponds to the nozzle pitch of the droplet discharge head 5, the ejection data SIA, when moving the droplet discharge head 5 to a predetermined position, the nozzles N ₁ ~ a data defining whether to supply a driving signal to the piezoelectric element _PZ 1 _{to PZ 180} corresponding to N _180.

In the present embodiment, 2-bit data is used to define whether or not to supply drive signals to the piezoelectric elements PZ _{1 to} PZ ₁₈₀ . Of these 2-bit data, the upper bit is called SIH and the lower bit is called SIL. When (SIH, SIL) = (0, 0), the non-supply (non-ejection) of the drive signal is specified. In the case of (SIH, SIL) = (0, 1), (1, 0), (1, 1), the supply (discharge) of the drive signal is defined. That is, the SIH data corresponding to each of the piezoelectric elements _{PZ 1 ~PZ 180 (SIH 1 ~SIH} 180), and the SIL data _(SIL 1 _{~SIL 180)} included in the discharge data SIA. Since such ejection data SIA differs depending on the pixel pattern of the color filter substrate P, it is sent from the control device 11 corresponding to the number of pixel patterns and stored in the drawing data memory 32. In this embodiment, 2-bit data is used to specify whether or not to supply a drive signal to the piezoelectric elements PZ _{1 to} PZ _180. However, the present invention is not limited to this, and 1-bit data may be used. good.

On the other hand, the COM selection data SIB is data that defines the type of drive signal supplied to each of the piezoelectric elements PZ _{1 to} PZ ₁₈₀ . In the present embodiment, one drive signal is selected and supplied from the four types of drive signals for each of the piezoelectric elements PZ _{1 to} PZ ₁₈₀ . In the present embodiment, the four types of drive signals are referred to as COM1, COM2, COM3, and COM4, respectively. That is, the COM selection data SIB is data that defines _one of COM1, COM2, COM3, and COM4 as a drive signal applied to each of the piezoelectric elements PZ _{1 to} PZ ₁₈₀ . Further, the COM selection data SIB includes drive waveform number data WN for defining the waveforms (drive waveforms) of the drive signals COM1, COM2, COM3, and COM4.

In this embodiment, since the drive signal is selected from four types, 2-bit data is required to define the drive signal. In the present embodiment, of the 2-bit data defining the drive signal, the upper bits are called WSH and the lower bits are called WSL. When (WSH, WSL) = (0, 0), COM1 is defined. When (WSH, WSL) = (0, 1), COM2 is defined. When (WSH, WSL) = (1, 0), COM3 is defined, and (WSH, WSL) = (1 In the case of 1), COM4 is specified. That is, the WSH data corresponding to each of the piezoelectric elements _{PZ 1 ~PZ 180 (WSH 1 ~WSH} 180), and WSL data _(WSL 1 _{to WSL 180)} is included in the COM selection data SIB. In the present embodiment, it is assumed that one of 64 types of combinations of drive waveforms of the drive signals COM1 to COM4 can be selected. That is, the drive waveform number data WN for defining the drive waveform is 6-bit data.

The COM selection data SIB is set according to the variation characteristic (discharge characteristic) of the droplet discharge amount of each of the nozzles N _{1 to} N ₁₈₀ of the droplet discharge head 5. FIG. 14 shows an example of a variation distribution of the droplet discharge amount. In FIG. 14, the horizontal axis represents the nozzle number, and the vertical axis represents the droplet discharge amount (weight). In addition, due to the characteristics of the droplet discharge head 5, the variation in droplet discharge amount is very large in the nozzles at both ends (nozzles N _{1 to} N ₉ and nozzles N _{171 to} N ₁₈₀ ). is doing. Even when the droplet discharge head 5 is actually used, 160 nozzles N _{10 to} N _{170 out} of 180 nozzles are used.

In order to correct the variation in the droplet discharge amount as shown in FIG. 14, each piezoelectric element is adjusted so that the droplet discharge amount of each nozzle N _{10 to} N ₁₇₀ approaches an appropriate weight (design value corresponding to the specification). the PZ ₁₀ ~ piezoelectric elements _{PZ 170} may be changed a drive signal supplied. For example, as shown in FIG. 14, in order to correct the droplet discharge amount of a nozzle that is largely deviated from the appropriate weight in the variation distribution 1 to the appropriate weight, the voltage value of the drive signal supplied to the piezoelectric element corresponding to this nozzle Should be increased.

Actually, the dispersion distribution of the droplet discharge amount as shown in FIG. 14 is measured in advance (for example, at the time of shipping inspection of the present droplet discharge apparatus IJ), and the droplet discharge of each nozzle N _{10 to} N ₁₇₀ is performed. A drive signal for each of the piezoelectric elements PZ _{10 to} PZ ₁₇₀ whose amount approaches the appropriate weight is obtained. In principle, the drive signals obtained for each of the piezoelectric elements PZ _{10 to} PZ ₁₇₀ may be prepared and supplied. However, in that case, a maximum of 160 types of drive signals must be prepared, and the number of parts can be reduced. Since problems such as an increase, an increase in device cost, an increase in size of the drive circuit board 30 and an increase in power consumption occur, it is difficult to realize in reality. Therefore, in the present embodiment, four types of drive signals are used to set the droplet discharge amounts of the nozzles N _{10 to} N ₁₇₀ so as to approach the appropriate weight. This is because by using at least four types of drive signals, variations in droplet discharge amount can be suppressed to a level that is not visually recognized by humans as variations (within 1.2% variation). The four types of driving signals thus obtained are set as COM1 to COM4 in the COM selection data SIB. Hereinafter, a specific example of allocation method of the drive signals COM1~COM4 for the piezoelectric elements _PZ 10 _{to PZ 170.}

First, in advance, to the piezoelectric elements _PZ 10 _{to PZ 170} by applying a reference driving voltage V0, to measure the variation in distribution of the droplet ejection volume of the nozzle _N 10 _{to N 170,} as shown in FIG. 15. Then, the range from the minimum weight to the maximum weight is equally divided into four to be range 1, range 2, range 3, and range 4. Next, the COM setting voltage is calculated for each of the ranges 1 to 4 based on the following formula (1), the COM setting voltage calculated for the range 1 is COM1, the COM setting voltage calculated for the range 2 is COM2, and the range 3 The COM setting voltage calculated for the COM is set as COM3, and the COM setting voltage calculated for the range 4 is set as COM4. In the following formula (1), K is a constant for converting the droplet weight into a voltage value.
COM set voltage = V0-K ((range center weight-proper weight) (1)

  Then, COM1 is assigned to the piezoelectric element corresponding to the nozzle included in the range 1, COM2 is assigned to the piezoelectric element corresponding to the nozzle included in the range 2, and COM3 is assigned to the piezoelectric element corresponding to the nozzle included in the range 3. Are assigned to the piezoelectric elements corresponding to the nozzles included in the range 4, and the COM selection data SIB is set based on the correspondence between these nozzles and COM1 to COM4. FIG. 16 is an example of the drive waveforms of COM1 to COM4 obtained in this way. Digital data (drive waveform data) of the drive waveforms of COM1 to COM4 is stored in a first drive waveform memory 34 and a second drive waveform memory 35 to be described later. The drive waveform number data WN indicates the drive waveform data of these COM1 to COM4.

Further, as described above, when the discharge pattern or nozzle duty of the droplet discharge head 5 changes, the variation characteristic of the droplet discharge amount shown in FIG. 15 changes. Therefore, the dispersion distribution of the droplet discharge amount is measured in advance for each discharge pattern and nozzle duty, and each of the piezoelectric elements PZ _{10 to} PZ ₁₇₀ such that the droplet discharge amount of each nozzle N _{10 to} N ₁₇₀ approaches the appropriate weight. Drive signals COM1 to COM4 are obtained, and COM selection data SIB corresponding to the nozzle duty is set. In this case, the COM selection data SIB is stored in the drawing data memory 32 corresponding to the ejection pattern and the nozzle duty.

  Note that it is not necessary to set the COM selection data SIB for all combinations of ejection / non-ejection (all ejection patterns), and it is only necessary to set the COM selection data SIB for the ejection patterns that are often used in practice. Similarly, it is not necessary to set COM selection data SIB for all nozzle duties from 0 to 100%, and COM selection is used for nozzle duties that are often used in practice (for example, 25%, 50%, 75%, 100%). Data SIB may be set.

  FIG. 17 is an explanatory diagram of a variation distribution of droplet discharge amounts when discharging is performed with three types of discharge patterns (pattern A, pattern B, and pattern C) having different nozzle duties (discharge patterns). FIG. 17A is an explanatory diagram of the variation distribution before the drive signal is adjusted by the above method, and FIG. 17B is an explanatory diagram of the variation distribution after the drive signal is adjusted by the above method. In FIG. 17, the horizontal axis represents the nozzle number, and the vertical axis represents the droplet discharge amount (weight). Symbols a, b, and c indicate distributions of variations in the droplet discharge amount when discharge is performed in the patterns A, B, and C, respectively.

As shown in FIG. 17A, in the pattern B and the pattern C, the nozzle duty decreases in the order of the pattern A, the pattern B, and the pattern C. Therefore, a large drive waveform distortion occurs in the pattern A, and the smallest drive waveform distortion occurs in the pattern C. As a result, the average droplet discharge amount of each of the nozzles N _{10 to} N ₁₇₀ decreases in the order of pattern A, pattern B, and pattern C.

Here, as shown in FIG. 17B, when the nozzles N _{10 to} N ₁₇₀ are classified into four groups for each pattern, and appropriate drive signals COM1 to COM4 are set for each group, FIG. The variation in the droplet discharge amount shown in a) is improved, and a substantially uniform discharge amount can be obtained for each of the nozzles N _{10 to} N ₁₇₀ . In FIG. 17B, symbols a ′, b ′, and c ′ indicate the droplet discharge amounts of the patterns A, B, and C when discharge is performed with the appropriate drive signals COM1 to COM4 for each group. The variation distribution is shown.

In this case, the droplet discharge amount of each of the nozzles N _{10 to} N ₁₇₀ is substantially uniform, but there is still variation in the discharge amount for each discharge pattern or nozzle duty. Therefore, the dispersion distribution of the droplet discharge amount is measured for each discharge pattern or nozzle duty, and the drive signals COM1 to COM4 are calculated so that the droplet discharge amount of each nozzle N _{10 to} N ₁₇₀ approaches the appropriate weight. COM selection data SIB corresponding to is set.

As a method for adjusting the droplet discharge amount, the method shown in FIG. 6 can be used. For example, when the droplet discharge amount is adjusted by the drive voltage, the COM setting voltage calculated using the equation (1) may be changed by a predetermined magnification. The drive voltage magnification is set for each ejection pattern or nozzle duty. Specifically, it is only necessary to change the magnification corresponding to the ratio between the average value of the droplet discharge amounts of the nozzles N _{10 to} N ₁₇₀ obtained from the variation distributions a ′ to c ′ and the appropriate weight. The drive voltage can be adjusted based on the correspondence between the droplet discharge amount and the drive voltage shown in FIG.

  As a method of adjusting the droplet discharge amount, the method shown in FIGS. 7 to 12 can also be used. That is, the correction can be performed by changing the drive frequency and the drive waveform of the drive signals COM1 to COM4. When the adjustment is performed according to the driving frequency, the driving voltage and the driving waveform are not changed, and a driving signal having a different discharge interval per unit time is generated for each discharge pattern or each nozzle duty. When the adjustment is performed according to the driving waveform, the driving voltage and the driving frequency are not changed, and a driving signal having a different rising time or falling time of the driving voltage is generated for each ejection pattern or nozzle duty. Further, the droplet discharge amount may be adjusted by combining two or more of the drive voltage, drive frequency, and drive waveform.

In FIG. 15, the nozzles N _{10 to} N ₁₇₀ are classified into four groups by equally dividing the range from the minimum weight to the maximum weight into four, but the nozzle classification method is not limited to this. For example, according to the order of the measured discharge amount (the higher discharge amount is the upper level and the lower discharge amount is the lower level), a predetermined number of nozzles are sequentially assigned from the lowest level to group 1, group 2, group 3, and group. 4 can be classified.

  In this case, it is desirable that the number of nozzles belonging to each group (group 1, group 2, group 3, group 4) be substantially equal. This is because if the number of nozzles is biased, a drive signal having a large number of nozzles in charge may be distorted. For example, since a piezoelectric element used as a drive element has a capacitor component, when the number of piezoelectric elements to which one type of drive signal is supplied increases, the capacitor component increases and the inrush current increases. The waveform is distorted. For this reason, even if a plurality of drive waveforms corresponding to variations in the ejection characteristics of each nozzle are prepared, waveform distortion occurs depending on the number of piezoelectric elements carried by one type of drive signal, resulting in variations in the droplet discharge amount. It may not be improved.

However, the discharge amount can also be adjusted by actively utilizing such waveform distortion. That is, in the COM selection data SIB, the droplets of the nozzles N _{10 to} N ₁₇₀ are considered in consideration of the distortion of the drive waveform of each of the drive signals COM1 to COM4 determined according to the number of piezoelectric elements assigned to each drive signal generation unit. The number of piezoelectric elements assigned to each of the drive signals COM1 to COM4 can also be set so that the discharge amount is made uniform. For example, when the droplet discharge amount is small, the number of drive elements assigned is increased to generate waveform distortion. As a result, distortion occurs in the drive waveform, and the discharge amount increases. Conversely, when the droplet discharge amount is large, the number of drive elements assigned is reduced to prevent drive waveform distortion. As a result, the drive waveform is maintained in an appropriate state, and the discharge amount is relatively reduced. Thereby, the discharge amount of the nozzle can be made uniform.

  Returning to FIG. 13, when the data read is requested by the drawing data write enable signal WE1, the chip selector signal CS1, and the output enable signal OE1, the drawing data memory 32 is an address designated by the drawing data address signal AD1. Is output to the switching circuit 50 of the droplet discharge head 5 as serial data, and the COM selection data SIB is output to the COM selection circuit 40 of the droplet discharge head 5 as serial data. The drive waveform number data WN is output to the address conversion circuit 33.

  The address conversion circuit 33 outputs an address signal AD3 indicating the storage destination address of the drive waveform data corresponding to the drive waveform number specified by the drive waveform number data WN to the first drive waveform memory 34 and the second drive waveform memory 35. To do. The first drive waveform memory 34 is an SRAM of 32K words × 16 bits, and is a memory for storing drive waveform digital data (drive waveform data) corresponding to COM1 and COM2. Similarly, the second drive waveform memory 35 is an SRAM of 32K words × 16 bits, and is a memory for storing drive waveform data corresponding to COM3 and COM4.

  The first drive waveform memory 34 and the second drive waveform memory 35 store the waveform data address signal AD2 when data write is requested by the waveform data write enable signal WE2, the chip selector signal CS2, and the output enable signal OE2. The drive waveform data signal WD is stored at the address specified by. The drive waveform data signal WD is a 4-byte data signal in which the upper 2 bytes are assigned to drive waveform data corresponding to COM3 and COM4, and the lower 2 bytes are assigned to drive waveform data corresponding to COM1 and COM2. The upper 2 bytes of drive waveform data signal WD are input to the first drive waveform memory 34, and the upper 2 bytes of drive waveform data signal WD are input to the second drive waveform memory 35.

  As described above, the first drive waveform memory 34 and the second drive waveform memory 35 can store 64 types of drive waveform data. These drive waveform data are stored in the number of COM selection data SIB ( In other words, it may be stored corresponding to the discharge pattern and the number of nozzle duties.

  Further, the first drive waveform memory 34 is stored in the address specified by the address signal AD3 when data read is requested by the waveform data write enable signal WE2, the chip selector signal CS2, and the output enable signal OE2. The output drive waveform data is output to the first D / A converter 36 and the second D / A converter 37. The second drive waveform memory 35, when data read is requested by the waveform data write enable signal WE2, the chip selector signal CS2 and the output enable signal OE2, is stored in the address specified by the address signal AD3. The waveform data is output to the third D / A converter 38 and the fourth D / A converter 39.

  The first D / A converter 36 latches the drive waveform data input from the first drive waveform memory 34 in synchronization with the rising edge of the DAC clock signal CLK1, and analog-converts the latched drive waveform data. A drive signal COM1 is generated and output to the COM selection circuit 40 of the droplet discharge head 5. The second D / A converter 37 latches the drive waveform data input from the first drive waveform memory 34 in synchronization with the rising edge of the DAC clock signal CLK2, and analog-converts the latched drive waveform data. A drive signal COM2 is generated and output to the COM selection circuit 40 of the droplet discharge head 5. The third D / A converter 38 latches the drive waveform data input from the second drive waveform memory 35 in synchronization with the rising edge of the DAC clock signal CLK1, and analog-converts the latched drive waveform data. A drive signal COM3 is generated and output to the COM selection circuit 40 of the droplet discharge head 5. The fourth D / A converter 39 latches the drive waveform data input from the second drive waveform memory 35 in synchronization with the rising edge of the DAC clock signal CLK2, and analog-converts the latched drive waveform data. A drive signal COM4 is generated and output to the COM selection circuit 40 of the droplet discharge head 5.

As shown in FIG. 18, the COM selection circuit 40 of the droplet discharge head 5 includes a shift register circuit 41, a latch circuit 42, and COM selection switch circuits CSW _{1 to} CSW ₁₈₀ . The shift register circuit 41 receives the clock signal CLK and the COM selection data SIB, converts the COM selection data SIB, which is serial data, into parallel data in synchronization with the clock signal CLK, and sequentially outputs them to the latch circuit 42. Specifically, the shift register circuit 41 sequentially outputs the WSH data corresponding to the piezoelectric elements _{PZ 1 ~PZ 180 (WSH 1 ~WSH} 180) and WSL data _(WSL 1 _{to WSL 180)} in parallel.

The latch circuit 42 latches the WSH data (WSH _{1 to} WSH ₁₈₀ ) and the WSL data (WSL _{1 to} WSL ₁₈₀ ) in synchronization with the latch signal LT, and each WSH data (WSH _{1 to} WSH ₁₈₀ ) and WSL Data (WSL _{1 to} WSL ₁₈₀ ) are collectively output to COM selection switch circuits CSW _{1 to} CSW ₁₈₀ . Specifically, the latch circuit 42 outputs WSH ₁ and WSL ₁ to the COM selection switch circuit CSW ₁ , outputs WSH ₂ and WSL ₂ to the COM selection switch circuit CSW ₂ , and similarly, WSH ₁₈₀ and WSL. ₁₈₀ is output to the COM selection switch circuit CSW ₁₈₀ .

Each of the COM selection switch circuits CSW _{1 to} CSW ₁₈₀ receives the drive signals COM _{1 to} COM 4, selects _one of the drive signals COM _{1 to} COM 4 according to the WSH and WSL data input from the latch circuit 42, and selects the selected drive and it outputs the signal to the switching element _SW 1 _{to SW 180} of the switching circuit 50 to be described later as _V 1 _{~V 180.} Specifically, COM selection switching circuit CSW _{1 is} the (WSH _1, WSL 1) = For (0,0), and select the drive signals _{COM1, (WSH 1, WSL 1} ) = (0,1) Drive signal COM2 is selected. If (WSH ₁ , WSL ₁ ) = (1, 0), the drive signal COM 3 is selected, and if (WSH ₁ , WSL ₁ ) = (1, 1), the drive signal is selected. select COM4, and outputs a driving signal selected to the switching element SW ₁ of the switching circuit 50 as _{V 1.} Similarly, COM selection switching circuit _{CSW 180} in _the case of _{(WSH 180,} WSL 180) = For (0,0), and select the drive signals _{COM1, (WSH 180, WSL 180} ) = (0,1) selects a drive signal _COM2, the case of _{(WSH 180,} WSL 180) = for (1,0), and select the drive signal _{COM3, (WSH 180, WSL 180} ) = (1,1), the drive signal COM4 , And outputs the selected drive signal to the switching element SW ₁₈₀ of the switching circuit 50 as V ₁₈₀ .

Subsequently, as illustrated in FIG. 19, the switching circuit 50 includes a shift register circuit 51, a latch circuit 52, OR circuits OR _{1 to} OR ₁₈₀ , a level shifter circuit 53, and switching elements SW _{1 to} SW ₁₈₀ . The shift register circuit 51 receives the clock signal CLK and the ejection data SIA, converts the ejection data SIA, which is serial data, into parallel data in synchronization with the clock signal CLK, and sequentially outputs the serial data to the latch circuit 52. Specifically, the shift register circuit 51 sequentially outputs the SIH data corresponding to the piezoelectric elements _{PZ 1 ~PZ 180 (SIH 1 ~SIH} 180) and SIL data _(SIL 1 _{~SIL 180)} in parallel.

The latch circuit 52 latches the SIH data (SIH _{1 to} SIH ₁₈₀ ) and SIL data (SIL _{1 to} SIL ₁₈₀ ) in synchronization with the latch signal LT, and each SIH data (SIH _{1 to} SIH ₁₈₀ ) and SIL Data (SIL _{1 to} SIL ₁₈₀ ) are collectively output to the OR circuits OR _{1 to} OR ₁₈₀ . Specifically, the latch circuit 52 outputs SIH ₁ and SIL ₁ to the OR circuit OR ₁ , outputs SIH ₂ and SIL ₂ to the OR circuit OR ₂ , and similarly, SIH ₁₈₀ and SIL ₁₈₀ are output from the OR circuit OR _2. Output to the OR circuit OR ₁₈₀ .

OR circuit OR ₁ outputs the switching signals _{S 1} is a logical sum of the SIH ₁ and SIL ₁ to the level shifter circuit 53. That is, if at least one of SIH ₁ and SIL ₁ is “1”, the supply (discharge) of the drive signal is defined, and therefore the switching signal S ₁ indicating “1” is output. OR circuit OR ₂ outputs the switching signal _{S 2} is a logical sum of the SIH ₂ and SIL ₂ to the level shifter circuit 53. Similarly, the OR circuit _{OR 180 outputs} a switching signal _{S 180} a logical sum of the _{SIH 180} and _{SIL 180} to the level shifter circuit 53.

The level shifter circuit 53 amplifies the voltage of the switching signals S _{1 to} S ₁₈₀ to a level at which the switching elements SW _{1 to} SW ₁₈₀ can be driven. Specifically, the level shifter circuit 53 amplifies the voltage of the switching signal S ₁ and outputs it to the switching element SW ₁ , a voltage amplifies the switching signal S ₂ and outputs it to the switching element SW ₂ , and so on. The voltage of S ₁₈₀ is amplified and output to switching element SW ₁₈₀ .

The switching element SW ₁ receives the driving signal V ₁ and the switching signal S ₁ and is turned on when the switching signal S ₁ indicating “1” is input. The driving element V ₁ is turned on by the piezoelectric element PZ shown in FIG. ₁ is output to one of the electrodes. The switching element SW ₂ receives the driving signal V ₂ and the switching signal S ₂ and is turned on when the switching signal S ₂ indicating “1” is input, and the driving signal V ₂ is turned on by the piezoelectric element PZ shown in FIG. ₂ to one of the electrodes. Similarly, the switching element SW ₁₈₀ receives the driving signal V ₁₈₀ and the switching signal S ₁₈₀ and is turned on when the switching signal S ₁₈₀ indicating “1” is input. The driving signal V ₁₈₀ is shown in FIG. It outputs to one electrode of the piezoelectric element PZ ₁₈₀ shown.

Returning to FIG. 13, the other electrodes of the piezoelectric elements PZ _{1 to} PZ ₁₈₀ are connected to each other within the droplet discharge head 5 and are commonly grounded to the ground on the drive circuit board 30 side. That is, the piezoelectric element PZ ₁ expands and contracts due to the potential difference between the drive signal V ₁ and the ground, and thereby droplets of the color filter material having a weight corresponding to the drive signal V ₁ are ejected from the nozzle N ₁ . Further, the piezoelectric element PZ ₂ expands and contracts due to the potential difference between the drive signal V ₂ and the ground, whereby a droplet of the color filter material having a weight corresponding to the drive signal V ₂ is ejected from the nozzle N ₂ . Similarly, the piezoelectric element PZ ₁₈₀ expands and contracts due to the potential difference between the drive signal V ₁₈₀ and the ground, and thereby droplets of the color filter material having a weight corresponding to the drive signal V ₁₈₀ are discharged from the nozzle N ₁₈₀ .

  As described above, according to the present droplet discharge apparatus IJ, the drive signal corresponding to the discharge pattern of the color filter substrate P and the nozzle duty is supplied to each drive element. It is possible to suppress a variation in the amount and form a uniform film layer.

  In the above embodiment, one droplet discharge head 5 and one drive circuit substrate 30 corresponding to the droplet discharge head 5 have been described as examples, but the same applies to a plurality of droplet discharge heads 5 and drive circuit substrates 30. A simple configuration and operation can be employed. Further, the piezoelectric element has been described as an example of the driving element. However, the present invention is not limited to this, and any other driving element can be used as long as the element can discharge the droplet by changing the volume of the cavity 24 in accordance with the driving signal. May be used. In the above-described embodiment, the case where four types of drive signals COM1 to COM4 are used has been described as an example. However, a plurality of types of drive signals may be used depending on the design conditions such as the device cost and the size of the drive circuit board 30. May be used.

  In the above embodiment, the color filter manufacturing apparatus has been described as an example of the droplet discharge apparatus of the present invention. However, the droplet discharge apparatus of the present invention is not limited to the color filter manufacturing apparatus, and discharges a liquid material. Thus, the present invention can be applied to various apparatuses for forming a desired pattern. For example, the present invention can be applied to a device for forming a liquid crystal containing an organic EL light emitting material on a substrate to form an organic EL element, a device for discharging a liquid containing a conductive material on a substrate to form a wiring pattern, and the like. is there.

It is a schematic block diagram of a droplet discharge apparatus. It is a schematic block diagram of the droplet discharge head with which a droplet discharge apparatus is equipped. It is explanatory drawing of the process of forming a color filter layer using a droplet discharge head. It is explanatory drawing of 1st Embodiment of the drive circuit of a droplet discharge apparatus. It is explanatory drawing of the variation distribution of the droplet discharge amount of a some discharge pattern. It is explanatory drawing of the relationship between a drive voltage and droplet discharge amount. It is explanatory drawing of the relationship between a drive frequency and droplet discharge amount. It is explanatory drawing in the case of discharging a droplet by changing a drive frequency within one pixel. It is explanatory drawing of the relationship between a drive waveform and droplet discharge amount. It is explanatory drawing of the relationship between a drive waveform and droplet discharge amount. It is explanatory drawing of the relationship between intermediate potential and droplet discharge amount. It is explanatory drawing of the relationship between intermediate potential and droplet discharge amount. It is explanatory drawing of 2nd Embodiment of the drive circuit of a droplet discharge apparatus. It is explanatory drawing of the variation distribution of the droplet discharge amount between nozzles. It is explanatory drawing of the setting method of COM selection data. It is an example of the waveform of a drive signal. It is explanatory drawing of the adjustment method of droplet discharge amount. It is a detailed explanatory view of a COM selection circuit of a droplet discharge head. It is a detailed explanatory view of a switching circuit of a droplet discharge head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 ... Droplet discharge head, 30 ... Drive circuit board, 32 ... Drawing data memory (drawing data storage means), 34 ... 1st drive waveform memory (drive waveform storage means), 35 ... 2nd drive waveform memory (drive) Waveform storage means), 36 ... first D / A converter (drive signal generation means), 37 ... second D / A converter (drive signal generation means), 38 ... third D / A converter (drive signal generation) Means), 39... Fourth D / A converter (drive signal generating means), 40... COM selection circuit (drive signal selection means), 50... Switching circuit (supply switching means), 100. ), CF ... color filter layer (film), COM, COM1, COM2, COM3, COM4 ... driving signals, IJ ... droplet discharge device, L ... liquid _{material, N, N} 1 ~N _{180 ...} nozzle, P ... Color filter substrate (discharge target), PZ, PZ _{1 to} PZ ₁₈₀ ... Piezoelectric element (drive element), SIA ... discharge data, SIB ... COM selection data (drive signal selection data)

Claims (10)

A droplet discharge head having a plurality of nozzles and driving elements provided corresponding to the nozzles;
Drive waveform storage means for storing waveform data of a drive signal supplied to each drive element,
The drive voltage or drive frequency of the drive signal is set according to the nozzle duty, which is the ratio of the used nozzles to all nozzles in the droplet discharge head,
The droplet discharge apparatus, wherein the drive waveform storage means stores waveform data of a drive signal having a drive voltage or a drive frequency corresponding to the nozzle duty for each nozzle duty. Drive signal selection means for selecting and supplying one drive signal from a plurality of types of drive signals for each of the drive elements;
Drawing data storage means for storing drive signal selection data indicating the correspondence between the drive element and the type of drive signal supplied to the drive element in correspondence with the nozzle duty;
Drive signal generation means for acquiring waveform data of the plurality of types of drive signals corresponding to the nozzle duty from the drive waveform storage means, and generating the plurality of types of drive signals based on the waveform data,
The drive signal selection means selects the type of drive signal supplied to each drive element from the drive signals generated by the drive signal generation means based on the drive signal selection data stored in the drawing data storage means. The droplet discharge device according to claim 1, wherein the droplet discharge device is selected. A plurality of the drive signal generating means are provided for the droplet discharge head,
The drive signal selection unit reads the drive signal selection data from the drawing data storage unit, and selects one drive signal from among the drive signals generated by the plurality of drive signal generation units for each of the drive elements. And supply
The droplet discharge apparatus according to claim 2, wherein the number of the drive signal generation units is smaller than the number of the nozzles provided in the droplet discharge head. The drawing data storage means outputs discharge data indicating a correspondence relationship between the drive element and information defining whether or not to supply a drive signal to the drive element between the used nozzle and the unused nozzle in the droplet discharge head. Memorize it corresponding to the discharge pattern that is a combination,
4. The droplet according to claim 2, further comprising a supply switching unit that switches supply or non-supply of the drive signal selected by the drive signal selection unit for each of the drive elements based on the ejection data. Discharge device. The drive signal selection unit and the supply switching unit are provided in the droplet discharge head,
5. The droplet discharge device according to claim 4, further comprising a drive circuit board provided with the drawing data storage unit, the drive waveform storage unit, and the drive signal generation unit.   6. The droplet discharge device according to claim 2, wherein the drive signal selection data is set so that the droplet discharge amount of each nozzle is made uniform.   The liquid droplet ejection apparatus according to claim 1, wherein the driving element is a piezoelectric element. A thin film forming method including a step of discharging a liquid material from a nozzle of the droplet discharge head onto the substrate while relatively moving a droplet discharge head having a plurality of nozzles and the substrate,
A method of forming a thin film, characterized in that the nozzles are ejected by drive signals having different drive voltages or drive frequencies in accordance with a nozzle duty which is a ratio of nozzles used to all nozzles of the droplet discharge head.   The plurality of nozzles are classified into a plurality of groups in consideration of the ejection characteristics of the nozzles, and ejection is performed by different drive signals for each of the groups. The thin film forming method according to claim 8, wherein the thin film forming method is designed.   The thin film forming method according to claim 9, wherein each of the plurality of groups is configured by a substantially equal number of nozzles.

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