JP2008191204A - Droplet discharging apparatus and its driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet discharging apparatus and its driving method by which droplet discharging amount can be accurately controlled. <P>SOLUTION: The droplet discharging apparatus is equipped with a droplet discharging head which has two or more nozzles and driving elements provided corresponding to respective nozzles, two or more driving signal producing means which respectively produces two or more kinds of driving signals and a driving signal selecting means which selects one among two or more kinds of driving signals and supplies it to respective driving elements. The driving signal selecting means selects one among two or more kinds of driving signals and supplies it to one electrode of the driving element and further a ground of the driving signal producing means for producing the selected driving signal is connected with another electrode of the driving element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

 The present invention relates to a droplet discharge device and a driving method thereof.

  In recent years, for example, a droplet discharge device (inkjet device) has attracted attention as a device for forming R (red), G (green), and B (blue) color filter layers on a color filter substrate for a display device. This droplet discharge device includes a droplet discharge head in which a plurality of nozzles capable of discharging droplets by driving a piezoelectric element such as a piezo element are formed. A color filter layer is formed by discharging droplets of a color filter material onto a pixel region on a color filter substrate.

For example, Patent Document 1 below includes a common waveform generation unit that generates a plurality of drive voltage waveforms corresponding to the ink discharge amount, and one drive voltage is generated from the plurality of drive voltage waveforms generated by the common waveform generation unit. An ink-jet head driving apparatus is disclosed in which a waveform is selected based on a gradation data signal and supplied to a piezoelectric element.
JP-A-9-17483

  FIG. 5 of Patent Document 1 describes an example of a plurality of drive voltage waveforms corresponding to the ink discharge amount. As shown in FIG. 5, a plurality of drive voltage waveforms are used whose phases are shifted from each other. Since the ground of the piezoelectric element is common in the droplet discharge head, when the drive voltage waveform having the above phase shift is supplied to each piezoelectric element, the adjacent piezoelectric element is connected via the ground line. There is a problem that current flows around and the drive voltage waveform of the piezoelectric element is distorted, and as a result, it is difficult to accurately control the droplet discharge amount.

 The present invention has been made in view of such circumstances, and an object of the present invention is to provide a droplet discharge device capable of accurately controlling the droplet discharge amount and a driving method thereof.

In order to achieve the above object, a droplet discharge device according to the present invention generates a plurality of types of drive signals and a droplet discharge head having a plurality of nozzles and drive elements provided corresponding to the nozzles. A droplet discharge apparatus comprising: a plurality of drive signal generating means; and a drive signal selecting means for selecting and supplying one of the plurality of types of drive signals for each drive element, wherein the drive signal selecting means Selects one of the plurality of types of drive signals and supplies the selected one to the one electrode of the drive element, and also generates the selected drive signal ground and the other of the drive elements. It is characterized by connecting electrodes.
According to the droplet discharge device having such characteristics, even when a drive signal having a phase shift is supplied to each drive element, the generation of a sneak current can be prevented. As a result, there is no distortion in the drive voltage waveform supplied to the piezoelectric element, and the droplet discharge amount can be accurately controlled.

In the droplet discharge device described above, the drive signal selection unit is connected to an input terminal corresponding to each type of drive signal and a ground of the drive signal generation unit that generates each type of drive signal. A ground terminal; an output terminal for outputting the selected drive signal; and a second ground terminal connected to the other electrode of the drive element; and the input terminal and the output terminal corresponding to the selected drive signal; It is preferable to connect the first ground terminal connected to the ground of the drive signal generating means for generating the selected drive signal and the second ground terminal.
By adopting such a configuration, the drive signal selecting means can be realized by a simple switch circuit.

In the above-described droplet discharge apparatus, it is preferable that the drive signal selection unit is provided in the droplet discharge head, and a drive circuit board provided with the drive signal generation unit is provided.
By adopting such a 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 droplet discharge device described above, the driving element is preferably a piezoelectric element.
By using the piezoelectric element in this way, it is possible to eject a droplet of an amount corresponding to the drive signal with high accuracy.

Also, the driving method of the 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 plurality of drives that respectively generate a plurality of types of drive signals. And a signal generating means for selecting and supplying one of the plurality of types of driving signals for each driving element, wherein one of the plurality of types of driving signals is selected. One is selected and supplied to one electrode of the drive element, and the ground of the drive signal generating means for generating the selected drive signal is connected to the other electrode of the drive element.
According to the driving method of the droplet discharge device having such a feature, even when a driving signal having a phase shift is supplied to each driving element, generation of a sneak current can be prevented. As a result, there is no distortion in the drive voltage waveform supplied to the piezoelectric element, and the droplet discharge amount can be accurately controlled.

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.
FIG. 1 is a schematic configuration diagram of a droplet discharge device IJ according to 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 (droplet discharge target) by, for example, an inkjet method. As shown in FIG. 1, the present droplet discharge apparatus IJ includes an apparatus mount 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, It comprises a second tank 9, a third tank 10 and a control device 11.

  In the following description, the XYZ orthogonal coordinate system shown in FIG. 1 is set, and each member will be described with reference to this XYZ orthogonal 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.

  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. As shown in FIG. 2A, the droplet discharge head 5 includes a plurality of (for example, 180) nozzles N _{1 to} N ₁₈₀ parallel to the Y-axis direction, and is input from the control device 11. Based on the drawing data and the drive control signal, droplets of the color filter material are ejected. 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. To supply a color filter material for B (blue).

FIG. 2B shows a detailed configuration diagram of the droplet discharge head 5. 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. And a liquid reservoir 22, a plurality of partition walls 23, and a plurality of cavities 24 provided between the diaphragm 20 and the nozzle plate 21. In addition, piezoelectric elements PZ _{1 to} PZ ₁₈₀ are arranged on the vibration plate 20 corresponding to the nozzles N _{1 to} N ₁₈₀ . These piezoelectric elements PZ _{1 to} PZ ₁₈₀ are, for example, piezoelectric elements.

The liquid reservoir 22 is filled with a liquid color filter 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, the color filter material is introduced into each cavity 24 from the liquid reservoir 22 through a supply port 24 a provided between the pair of partition walls 23.

FIG. 2C is a front sectional view of one nozzle (nozzle N ₁ ) of the droplet discharge head 5. As shown in FIG. 2 (c), the piezoelectric elements PZ ₁ is obtained by sandwiching the piezoelectric material 25 by a pair of electrodes 26, configured to piezoelectric material 25 contracts when a driving signal is applied to the pair of electrodes 26 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, both the piezoelectric element PZ ₁ and the diaphragm 20 return to their original shapes, and the cavity 24
From the back to the original volume, the pressure rises in the color filter material in the cavity 24, the droplet L of the color filter material is ejected toward the nozzle N ₁ on the color filter substrate P.

Note that the number of nozzles provided in the droplet discharge head 5 can be arbitrarily changed, and a plurality of nozzles may be provided in parallel to the Y-axis direction as well as one row. Further, the number of droplet discharge heads 5 arranged in the carriage 4 can be arbitrarily changed. Furthermore, a configuration may be adopted in which a plurality of carriages 4 are provided in units of sub-carriages.

Although not shown in FIGS. 1 and 2, a drive circuit board 30 (see FIG. 3) for supplying drive signals to the piezoelectric elements PZ _{1 to} PZ ₁₈₀ described above corresponds to the droplet discharge head 5. Is provided. This drive circuit board 30 is connected to the control device 11 by a PCI bus, and based on drawing data and drive control signals input from the control device 11, drive signals to be applied to the piezoelectric elements PZ _{1 to} PZ ₁₈₀ . Selection, drive signal generation, ejection timing control, and the like are performed. Details of the drive circuit board 30 will be described later.

  Returning to FIG. 1, 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. The carriage 4 is moved in the Y-axis direction and the Z-axis direction based on the carriage position control signal indicating the Y-coordinate and Z-coordinate of the carriage 4 input from. 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.

  Next, the circuit configuration of the drive circuit board 30 and the droplet discharge head 5 will be described in detail. Although one drive circuit board 30 is provided for one droplet discharge head 5, the droplet discharge head 5 corresponding to each of R (red), G (green), and B (blue) and Since all the drive circuit boards 30 have the same configuration, the following description will be made using one droplet discharge head 5 and the drive circuit board 30 for convenience.

As shown in FIG. 3, 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, and a first D / A converter 36. , A second D / A converter 37, a third D / A converter 38, and a fourth D / A converter 39. The droplet discharge head 5 includes a COM selection circuit 40, a switching circuit 50, and a piezoelectric element array 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 first D / A converter 36, the second D / A converter 37, the third D / A converter 38, and the fourth D / A converter 39 correspond to the drive signal generating means in the present invention, The COM selection circuit 40 corresponds to drive signal selection means in the present invention.

  The control device 11 and the interface 31 of the drive circuit board 30 are connected by a PCI bus (not shown), and the control device 11 passes the PCI bus via the PCI bus, and the clock signal CLK, the 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, output enable signal 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. Further, 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. Further, the interface 31 outputs the DAC clock signal CLK1 to the first D / A converter 36 and the third D / A converter 38, and the DAC clock signal CLK2 to the second D / A converter 37 and the fourth D / A. / A output to the converter 39. The interface 31 also outputs 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.

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. The dot pitch in the Y-axis direction of this matrix corresponds to the nozzle pitch of the droplet discharge head 5, that is, the above-described discharge data SIA is obtained when each droplet discharge head 5 is moved to a predetermined position. a data defining whether to supply a driving signal to the piezoelectric element _PZ 1 _{to PZ 180} corresponding to the nozzle _N 1 _{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. Of course it is 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 characteristics of the droplet discharge amounts of the nozzles N _{1 to} N ₁₈₀ of the droplet discharge head 5. FIG. 4 shows an example of the variation distribution of the droplet discharge amount. In FIG. 4, 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. 4, the piezoelectric elements PZ ₁₀ to PZ ₁₇₀ are arranged so that the droplet discharge amounts of the nozzles N _{10 to} N ₁₇₀ approach the appropriate weight. What is necessary is just to change the drive signal to supply. For example, as shown in FIG. 4, 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. 4 is measured in advance (for example, at the time of shipping inspection of the droplet discharge apparatus IJ), and the droplet discharge of each of the nozzles 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 electric 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. 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. 6 shows an example of the drive waveforms of COM1 to COM4 obtained in this way. The digital data (drive waveform data) of the drive waveforms of these 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. As shown in FIG. 6, the drive waveform data of the drive signals COM1 to COM4 are set so that the phases are different from each other.

Here, the droplet discharge amount of each nozzle depends on the mechanical crosstalk due to the driving of the proximity nozzle or the influence of the impedance of the drive signal, and the nozzle duty of the droplet discharge head 5 (nozzles N _{10 to} N at the discharge timing). It is known that it changes in accordance with the concept of ₁₇₀ driving rate. Accordingly, when the nozzle duty of the droplet discharge head 5 changes, the variation characteristic of the droplet discharge amount shown in FIG. 5 changes. Therefore, in advance, the dispersion distribution of the droplet discharge amount is measured for each nozzle duty, and the drive signal of each of the piezoelectric elements PZ _{10 to} PZ ₁₇₀ so that the droplet discharge amount of each nozzle N _{10 to} N ₁₇₀ approaches an appropriate weight. COM1 to COM4 are obtained, and COM selection data SIB corresponding to the nozzle duty is set. In other words, the COM selection data SIB is stored in the drawing data memory 32 corresponding to the number of nozzle duties. Note that it is not necessary to set the COM selection data SIB for all the nozzle duties from 0 to 100%, and the COM selection data for nozzle duties that are often used in practice (for example, 25%, 50%, 75%, 100%). What is necessary is just to set SIB.

  Returning to FIG. 3, 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.

In the present embodiment, the maximum length of one drive waveform is set to 25 μs, and a first D / A converter 36, a second D / A converter 37, a third D / A converter 38, and a fourth D, which will be described later. The time axis resolution of the / A converter 39 is assumed to be 20 MHz. In this case, one drive waveform data is 500 bytes, but the memory has a boundary of 200h (512 bytes) for easy address operation. FIG. 7 shows the storage destination address of the drive waveform data in the first drive waveform memory 34 and the second drive waveform memory 35. As shown in FIG. 7, the addresses “00000h” to “07FFFh” of the first drive waveform memory 34 have
Drive waveform data corresponding to COM1 of each drive waveform number “0” to “63” is stored every 200 h, and drive waveform data corresponding to COM2 is stored at addresses “08000h” to “0FFFFh”. Similarly, drive waveform data corresponding to COM3 of each drive waveform number “0” to “63” is stored at addresses “00000h” to “07FFFh” of the second drive waveform memory 35 every 200 h. “08000h” to “0FFFFh” store drive waveform data corresponding to COM4.
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 ( That is, it may be stored corresponding to 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.

FIG. 8 is a detailed configuration diagram of the COM selection circuit 40, the switching circuit 50, and the piezoelectric element array 60 of the droplet discharge head 5. As shown in FIG. 8, the COM selection circuit 40 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 includes input terminals a 1 to a 4, first ground terminals b 1 to b 4, an output terminal c 1, and a second ground terminal d 1. The drive signal COM1 is input to the input terminal a1, and the first ground terminal b1 is connected to the ground GND1 of the first D / A converter 36 of the drive circuit board 30. The drive signal COM2 is input to the input terminal a2, and the first ground terminal b2 is connected to the ground GND2 of the second D / A converter 37 of the drive circuit board 30. The drive signal COM3 is input to the input terminal a3, and the first ground terminal b3 is connected to the ground GND3 of the third D / A converter 38 of the drive circuit board 30. The drive signal COM4 is input to the input terminal a4, and the first ground terminal b4 is connected to the ground GND4 of the fourth D / A converter 39 of the drive circuit board 30. The grounds GND1 to GND4 are commonly grounded in the drive circuit board 30.

Output terminal c1 of the COM selection switching circuit CSW ₁ is connected to an input terminal of the switching element SW ₁ of the switching circuit 50, the second ground terminal d1 is connected to the other electrode of the piezoelectric elements PZ _1, the second wires connecting the ground terminal d1 to the other electrode of the piezoelectric element PZ ₁ and the ground line G _1. Similarly, the output terminal c1 of the COM selection switch circuit CSW ₁₈₀ is connected to the input terminal of the switching element SW ₁₈₀ of the switching circuit 50, and the second ground terminal d1 is connected to the other electrode of the piezoelectric element PZ _180. A connection wiring from the second ground terminal d1 to the other electrode of the piezoelectric element PZ ₁₈₀ is defined as a ground line _G180 .

The COM selection switch circuit CSW ₁ connects the input terminal a 1 to the output terminal c 1 and connects the first ground terminal b 1 to the second ground terminal d ₁ when (WSH ₁ , WSL ₁ ) = (0, 0). That is, in this case, COM selection switching circuit CSW ₁ selects the drive signals COM1, and outputs a drive signal corresponding selected as _{V 1} to the input terminal of the switching element SW _1, connects the ground line _{G 1} and the ground GND1 To do. Further, when (WSH ₁ , WSL ₁ ) = (0, ₁ ), the COM selection switch circuit CSW ₁ connects the input terminal a 2 to the output terminal c 1 and connects the first ground terminal b 2 to the second ground terminal d 1. To do. That is, in this case, COM selection switching circuit CSW ₁ selects the drive signal COM2, and outputs a drive signal corresponding selected as _{V 1} to the input terminal of the switching element SW _1, connects the ground line _{G 1} and the ground GND2 To do. Further, when (WSH ₁ , WSL ₁ ) = (1, 0), the COM selection switch circuit CSW ₁ connects the input terminal a3 to the output terminal c1 and connects the first ground terminal b3 to the second ground terminal d1. To do. That is, in this case, COM selection switching circuit CSW ₁ selects the drive signal COM3, and outputs a drive signal corresponding selected as _{V 1} to the input terminal of the switching element SW _1, connects the ground line _{G 1} and the ground GND3 To do. Further, the COM selection switch circuit CSW ₁ connects the input terminal a4 to the output terminal c1 and the first ground terminal b4 to the second ground terminal d1 when (WSH ₁ , WSL ₁ ) = (1, 1). To do. That is, in this case, COM selection switching circuit CSW ₁ selects the drive signal COM4, and outputs a drive signal corresponding selected as _{V 1} to the input terminal of the switching element SW _1, connects the ground line _{G 1} and the ground GND4 To do.

Similarly, the COM selection switch circuit CSW ₁₈₀ connects the input terminal a1 to the output terminal c1 and the first ground terminal b1 to the second ground terminal d1 when (WSH ₁₈₀ , WSL ₁₈₀ ) = (0, 0). Connect to. That is, in this case, COM selection switching circuit _{CSW 180} selects the drive signal COM1, and outputs a drive signal corresponding selected as _{V 180} to an input terminal of the switching element _{SW 180,} connects the ground line _{G 180} and the ground GND1 To do. Further, when (WSH ₁₈₀ , WSL ₁₈₀ ) = (0, 1), the COM selection switch circuit CSW ₁₈₀ connects the input terminal a2 to the output terminal c1 and connects the first ground terminal b2 to the second ground terminal d1. To do. That is, in this case, COM selection switching circuit _{CSW 180} selects the drive signal COM2, and outputs a drive signal corresponding selected as _{V 180} to an input terminal of the switching element _{SW 180,} connects the ground line _{G 180} and the ground GND2 To do. Further, when (WSH ₁₈₀ , WSL ₁₈₀ ) = (1, 0), the COM selection switch circuit CSW ₁₈₀ connects the input terminal a 3 to the output terminal c 1 and connects the first ground terminal b 3 to the second ground terminal d 1. To do. That is, in this case, COM selection switching circuit _{CSW 180} selects the drive signal COM3, and outputs a drive signal corresponding selected as _{V 180} to an input terminal of the switching element _{SW 180,} connects the ground line _{G 180} and the ground GND3 To do. Further, the COM selection switch circuit CSW ₁₈₀ connects the input terminal a4 to the output terminal c1 and connects the first ground terminal b4 to the second ground terminal d1 when (WSH ₁₈₀ , WSL ₁₈₀ ) = (1, 1). To do. That is, in this case, COM selection switching circuit _{CSW 180} selects the drive signal COM4, and outputs a drive signal corresponding selected as _{V 180} to an input terminal of the switching element _{SW 180,} connects the ground line _{G 180} and the ground GND4 To do.

The switching circuit 50 includes a shift register circuit 51, a latch circuit 52, logical sum 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, and the driving signal V ₁ is switched to _one of the piezoelectric elements PZ ₁ . Output to electrode. 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 switched to one of the piezoelectric elements PZ ₂ . Output to electrode. 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 switching element SW ₁₈₀ receives the driving signal V ₁₈₀ as the piezoelectric element PZ. Output to one of the ₁₈₀ electrodes.

That is, the piezoelectric element PZ ₁ expands and contracts due to the potential difference between the drive signal V ₁ and the ground line G _1, 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 . In addition, the piezoelectric element PZ ₂ expands and contracts due to the potential difference between the drive signal V ₂ and the ground line G ₂ , whereby droplets of color filter material having a weight corresponding to the drive signal V ₂ are ejected from the nozzle N ₂ . Similarly, the piezoelectric elements _{PZ 180} expand and contract by the potential difference between the drive signal _{V 180} and a ground line _{G 180,} thereby droplets of the weight of the color filter material in accordance with the drive signal _{V 180} is ejected from the nozzle _{N 180} The

Next, the operation of the droplet discharge apparatus IJ configured as described above will be described.
First, the ejection data SIA set in advance according to the pixel pattern of the color filter substrate P and the COM selection data SIB set for each nozzle duty are stored in the drawing data memory 32 of the drive circuit board 30, and the COM selection is performed. The drive waveform data of COM1 to COM4 corresponding to the data SIB is stored in advance in the first drive waveform memory 34 and the second drive waveform memory 35.

  Specifically, the control device 11 via the interface 31 draws data SI (discharge data SIA and COM selection data SIB) and a drawing data address signal indicating the storage destination addresses of these discharge data SIA and COM selection data SIB. AD1 and a drawing data write enable signal WE1, a chip selector signal CS1, and an output enable signal OE1 indicating a data write request are output to the drawing data memory 32. Thus, the ejection data SIA and the COM selection data SIB are sequentially stored in the rendering data memory 32 at the storage destination address specified by the rendering data address signal AD1.

  In addition, the control device 11 receives drive waveform data WD, a waveform data address signal AD2, a waveform data write enable signal WE2, a chip selector signal CS2, and an output enable signal OE2 indicating a data write request via the interface 31. The data is output to the first drive waveform memory 34 and the second drive waveform memory 35. Describing in detail with reference to FIG. 7, for example, when storing the drive waveform data of the drive waveform number “0”, the waveform data address signal AD2 designating the address “+ 00000h” is used as the first drive waveform memory 34 and the first drive waveform memory 34. The driving waveform data WD corresponding to the lower 2 bytes assigned to the driving waveform data of COM1 is input to the first driving waveform memory 34, and the higher order assigned to the driving waveform data of COM3. Two-byte drive waveform data WD is input to the second drive waveform memory 35. As a result, the drive waveform data of COM1 for 2 bytes is stored in the address “+ 00000h” of the first drive waveform memory 34, and 2 bytes are stored in the address “+ 00000h” of the second drive waveform memory 35. The drive waveform data of COM3 is stored. By repeating the same processing until the address “+ 001FFh”, the drive waveform data for one waveform (512 bytes) of COM1 corresponding to the drive waveform number “0” is stored in the first drive waveform memory 34, and the COM3 The drive waveform data for one waveform is stored in the second drive waveform memory 35. The same processing is performed for the drive waveform numbers “1” to “63”, and the drive waveform data for one waveform of COM1 corresponding to each drive waveform number is stored in the first drive waveform memory 34, and COM3 Is stored in the second drive waveform memory 35.

 Next, the waveform data address signal AD2 designating the address “+ 08000h” is input to the first drive waveform memory 34 and the second drive waveform memory 35, and the drive waveform data of COM2 corresponding to the drive waveform number “0” is input. Is input to the first drive waveform memory 34, and the drive waveform data WD for the upper 2 bytes assigned to the drive waveform data of COM4 is input to the second drive waveform memory. 35. As a result, the COM2 drive waveform data for 2 bytes is stored in the address “+ 08000h” of the first drive waveform memory 34, and 2 bytes are stored in the address “+ 08000h” of the second drive waveform memory 35. The drive waveform data of COM4 is stored. By repeating the same processing up to the address “+ 081FFh”, the drive waveform data for one waveform of COM2 corresponding to the drive waveform number “0” is stored in the first drive waveform memory 34, and one waveform of COM4 is stored. The drive waveform data is stored in the second drive waveform memory 35. The same processing is performed for the drive waveform numbers “1” to “63”, and the drive waveform data for one waveform of COM2 corresponding to each drive waveform number is stored in the first drive waveform memory 34, and COM4 Is stored in the second drive waveform memory 35.

  Through the processing as described above, the ejection data SIA set in advance according to the pixel pattern of the color filter substrate P and the COM selection data SIB set for each nozzle duty are stored in the drawing data memory 32, and the COM selection is performed. The drive waveform data of COM1 to COM4 corresponding to the data SIB is stored in the first drive waveform memory 34 and the second drive waveform memory 35.

Next, the operation of actually discharging the color filter material onto the color filter substrate P will be described with reference to the timing chart of FIG.
When the color filter substrate P is transported to the work stage 2 and the control device 11 acquires information about the color filter substrate P (information such as a pixel pattern and a substrate size) from the host control device, the control device 11 receives the information on the transported color filter substrate P. Corresponding ejection data SIA is determined.
Further, the control device 11 obtains the nozzle duty based on the information regarding the color filter substrate P, and determines the COM selection data SIB corresponding to the nozzle duty. Then, the control device 11 controls the stage moving device 3 and the carriage moving device 6 to move the droplet discharge head 5 to predetermined XYZ coordinates on the color filter substrate P.

  Subsequently, the control device 11 draws the drawing data address signal AD1 indicating the storage destination address of the ejection data SIA and the COM selection data SIB determined as described above, the drawing data write enable signal WE1 indicating the data read request, and the chip selector signal. CS 1 and output enable signal OE 1 are output to the drawing data memory 32 of the drive circuit board 30. As a result, the ejection data SIA corresponding to the conveyed color filter substrate P is output to the switching circuit 50 (specifically, the shift register circuit 51) of the droplet ejection head 5, and corresponds to the nozzle duty of the color filter substrate P. The COM selection data SIB is output to the COM selection circuit 40 (specifically, the shift register circuit 41) of the droplet discharge head 5. The drive waveform number data WN included in the COM selection data SIB is output to the address conversion circuit 33.

As shown in FIG. 9, it is assumed that the ejection data SIA is output to the shift register circuit 51 of the switching circuit 50 and the COM selection data SIB is output to the shift register circuit 41 of the COM selection circuit 40 at time T1. The shift register circuit 51 converts the ejection data SIA, which is serial data, into parallel data in synchronization with the clock signal CLK and sequentially outputs it to the latch circuit 52 during the period from time T1 to T2. That, SIH data corresponding to the piezoelectric elements _{PZ 1 ~PZ 180 (SIH 1 ~SIH} 180) and SIL data _(SIL 1 _{~SIL 180)} are sequentially output in parallel. On the other hand, the shift register circuit 41 converts the COM selection data SIB, which is serial data, into parallel data and sequentially outputs it to the latch circuit 42 in synchronization with the clock signal CLK during the period from the clock time T1 to T2. That, WSH data corresponding to the piezoelectric elements _{PZ 1 ~PZ 180 (WSH 1 ~WSH} 180) and WSL data _(WSL 1 _{to WSL 180)} are sequentially output in parallel.

  Here, the address conversion circuit 33, the first drive waveform memory 34 and the second drive waveform memory 35, the first D / A converter 36, and the second D / A converter 37 in the period from the time T1 to the time T2. The operation of the third D / A converter 38 and the fourth D / A converter 39 will be described with reference to the timing chart of FIG.

  As shown in FIG. 10, at time T1 ′, the address conversion circuit 33 indicates the storage address of the drive waveform data corresponding to the drive waveform number specified by the drive waveform number data WN in synchronization with the rising edge of the clock signal CLK. The address signal AD3 is output to the first drive waveform memory 34 and the second drive waveform memory 35. For example, assuming that the drive waveform number “0” is designated, the address signal AD3 indicates the address “+ 00000h”. At time T2 ′, the first drive waveform memory 34 converts the drive waveform data for 2 bytes of COM1 stored at the address “+ 00000h” into the first D / A converter 36 and the second D / A converter. The second drive waveform memory 35 outputs the drive waveform data for 2 bytes of COM3 stored at the address “+ 00000h” to the third D / A converter 38 and the fourth D / A converter. 39.

  When the rising edge of the DAC clock signal CLK1 occurs at time T3 ′, the first D / A converter 36 latches the drive waveform data for 2 bytes of COM1 in synchronization with the rising edge of the DAC clock signal CLK1. Similarly, the third D / A converter 38 latches and captures the drive waveform data for 2 bytes of COM3 in synchronization with the rising edge of the DAC clock signal CLK1.

  Further, at this time T3 ′, the address conversion circuit 33 sends the address signal AD3 indicating the address “+ 08000h” to the first drive waveform memory 34 and the second drive waveform memory 35 in synchronization with the rising edge of the clock signal CLK. Output to. At time T4 ′, the first drive waveform memory 34 converts the drive waveform data for 2 bytes of COM2 stored at the address “+ 08000h” into the first D / A converter 36 and the second D / A. The second driving waveform memory 35 outputs the driving waveform data for 2 bytes of COM4 stored at the address “+ 08000h” to the third D / A converter 38 and the fourth D / A. Output to the A converter 39.

  When the rising edge of the DAC clock signal CLK2 occurs at time T5 ′, the second D / A converter 37 latches the drive waveform data for 2 bytes of COM2 in synchronization with the rising edge of the DAC clock signal CLK2. Similarly, the fourth D / A converter 39 latches and captures the drive waveform data for 2 bytes of COM4 in synchronization with the rising edge of the DAC clock signal CLK2.

  Thus, the first D / A converter 36 captures only the drive waveform data of COM1, the second D / A converter 37 captures only the drive waveform data of COM2, and the third D / A converter 38 drives the drive of COM3. Only the waveform data is captured, and the fourth D / A converter 39 captures only the drive waveform data of COM4. Thereafter, the address conversion circuit 33 increments the address in synchronization with the rising edge of the clock signal CLK, and 512 corresponding to the drive waveform number “0” from the first drive waveform memory 34 and the second drive waveform memory 35. Drive waveform data of COM1 to COM4 for one byte (one waveform) is output.

  Then, the first D / A converter 36 takes in the drive waveform data of COM1 for one waveform, converts it to analog, generates a drive signal COM1, and outputs it to the COM selection circuit 40 of the droplet discharge head 5. Further, the second D / A converter 37 takes in the drive waveform data of COM2 for one waveform, converts it to analog, generates a drive signal COM2, and outputs it to the COM selection circuit 40 of the droplet discharge head 5. Further, the third D / A converter 38 takes in the drive waveform data of the COM 3 for one waveform, converts it to analog, generates a drive signal COM 3, and outputs it to the COM selection circuit 40 of the droplet discharge head 5. Further, the fourth D / A converter 39 takes in the drive waveform data of the COM 4 for one waveform, converts it to analog, generates a drive signal COM 4, and outputs it to the COM selection circuit 40 of the droplet discharge head 5.

  As described above, the operation shown in FIG. 10 is performed in the period of time T1 to T2 in FIG. 9, and the drive signals COM1 to COM4 are input to the COM selection circuit 40 of the droplet discharge head 5. During the operation shown in FIG. 10, the first drive waveform memory 34 and the second drive waveform memory 35 have a waveform data write enable signal WE2, a chip selector signal CS2, and an output enable signal OE2 indicating a data read request. Entered.

Returning to FIG. 9, when the rising edge of the latch signal LT occurs at time T3, the latch circuit 42 of the COM selection circuit 40 synchronizes with the rising edge of the latch signal LT, and the WSH data (WSH _{1 to} WSH ₁₈₀ ). And WSL data (WSL _{1 to} WSL ₁₈₀ ) are latched, and the WSH data (WSH _{1 to} WSH ₁₈₀ ) and WSL data (WSL _{1 to} WSL ₁₈₀ ) are collectively collected at time T 4 when the falling of the latch signal LT occurs. The data is output to the COM selection switch circuits CSW _{1 to} CSW ₁₈₀ . Here, as shown in FIG. 9, the data of (WSH ₁ , WSL ₁ ) = (0, 1) is input to the COM selection switch circuit CSW ₁ , and (WSH ₂ , WSL ₂ ) = (0, 1) Assume that data is input to the COM selection switch circuit CSW _2, and similarly, data of (WSH ₁₈₀ , WSL ₁₈₀ ) = (0, 1) is input to the COM selection switch circuit CSW ₁₈₀ . That is, the COM selection switch circuits CSW _{1 to} CSW ₁₈₀ select the drive signal COM 2 and output the drive signals V _{1 to} V ₁₈₀ to the corresponding switching elements SW _{1 to} SW ₁₈₀ . At this time, the ground lines G _{1 to} G ₁₈₀ are connected to the ground GND 2.

Note that COM1 to COM4 generated from the drive waveform data corresponding to the drive waveform number “0” are flat waveforms having a voltage value slightly higher than the ground level as shown in FIG. COM1 to COM4 generated from the drive waveform data corresponding to the drive waveform number “0” transitions the piezoelectric elements PZ _{1 to} PZ ₁₈₀ to a standby state when the liquid droplet ejection apparatus IJ is turned on. The voltage value is set to a level at which droplets are not ejected.

At time T3, the latch circuit 52 of the switching circuit 50, in synchronization with the rise of the latch signal LT, latches the SIH data _(SIH 1 _{~SIH 180)} and SIL data _(SIL 1 _{~SIL 180),} a latch signal Each SIH data (SIH _{1 to} SIH ₁₈₀ ) and SIL data (SIL _{1 to} SIL ₁₈₀ ) are output to the OR circuits OR _{1 to} OR ₁₈₀ at a time T 4 when the falling of LT occurs. Here, as shown in FIG. 9, the data of (SIH ₁ , SIL ₁ ) = (0, 1) is input to the OR circuit OR _1, and the data of (SIH ₂ , SIL ₂ ) = (0, 1) Is input to the OR circuit OR _2, and similarly, data of (SIH ₁₈₀ , SIL ₁₈₀ ) = (0, 1) is input to the OR circuit OR ₁₈₀ . That is, each of the OR circuits OR _{1 to} OR ₁₈₀ outputs the high level switching signals S _{1 to} S ₁₈₀ to the level shifter circuit 53, and the level shifter circuit 53 amplifies each of the switching signals S _{1 to} S ₁₈₀ and outputs each switching element. Output to SW _{1 to} SW ₁₈₀ .

As described above, in time T4, by the high level of the switching signal _S 1 _{to S 180} is input to each of the switching elements _SW 1 _{to SW 180,} the switching elements _SW 1 _{to SW 180} are turned on, COM selection The drive signals V _{1 to} V ₁₈₀ supplied from the circuit 40 are output to the corresponding piezoelectric elements PZ _{1 to} PZ ₁₈₀ . As a result, each of the piezoelectric elements PZ _{1 to} PZ ₁₈₀ transitions to a standby state, and preparation for droplet discharge is completed.

  On the other hand, at time T5, the controller 11 draws the drawing data address signal AD1 indicating the storage destination address of the next ejection data SIA and COM selection data SIB, the drawing data write enable signal WE1 indicating the data read request, and the chip selector signal CS1. The output enable signal OE1 is output to the drawing data memory 32 of the drive circuit board 30. Here, the next ejection data SIA and COM selection data SIB are data for ejecting droplets at the current position of the droplet ejection head 5. As a result, the ejection data SIA corresponding to the current position of the droplet ejection head 5 is output to the switching circuit 50 (specifically, the shift register circuit 51) of the droplet ejection head 5, and the COM selection data SIB is output from the droplet ejection head. 5 COM selection circuit 40 (specifically, shift register circuit 41). Further, the drive waveform number data WN included in the COM selection data SIB at this time is output to the address conversion circuit 33. Here, it is assumed that the drive waveform number “1” is designated.

  At time T5, the ejection data SIA is output to the shift register circuit 51 of the switching circuit 50, and the COM selection data SIB is output to the shift register circuit 41 of the COM selection circuit 40. The shift register circuit 51 converts the ejection data SIA, which is serial data, into parallel data in synchronization with the clock signal CLK and sequentially outputs it to the latch circuit 52 during the period from time T5 to T6. Here, during the period from time T5 to T6, the drive signal COM1 corresponding to the drive waveform number “1” corresponding to the drive waveform number “1” is supplied from the first D / A converter 36 by the operation as described in FIG. The drive signal COM2 for one waveform corresponding to the drive waveform number “1” is output from the second D / A converter 37 to the COM selection circuit 40 of the droplet discharge head 5, and the COM selection circuit 40 of the droplet discharge head 5. The third D / A converter 38 outputs a drive signal COM3 for one waveform corresponding to the drive waveform number “1” to the COM selection circuit 40 of the droplet discharge head 5, and the fourth D / A The A converter 39 outputs a drive signal COM4 for one waveform corresponding to the drive waveform number “1” to the COM selection circuit 40 of the droplet discharge head 5. These drive signals COM1 to COM4 are output at different phases as shown in FIG.

When the rising edge of the latch signal LT occurs at time T7, the latch circuit 42 of the COM selection circuit 40 synchronizes with the rising edge of the latch signal LT, and the WSH data (WSH _{1 to} WSH ₁₈₀ ) and WSL data (WSL ₁ to WSL ₁ to WSL data). WSL ₁₈₀ ) is latched, and WSH data (WSH _{1 to} WSH ₁₈₀ ) and WSL data (WSL _{1 to} WSL ₁₈₀ ) are collectively collected at time T 8 when the falling edge of the latch signal LT occurs. COM selection switch circuits CSW ₁ to CSW ₁ to Output to CSW ₁₈₀ . Here, as shown in FIG. 9, the data of (WSH ₁ , WSL ₁ ) = (1, 0) is input to the COM selection switch circuit CSW ₁ , and (WSH ₂ , WSL ₂ ) = (1, 0) It is assumed that data is input to the COM selection switch circuit CSW ₂ and data of (WSH ₁₈₀ , WSL ₁₈₀ ) = (0, 0) is input to the COM selection switch circuit CSW ₁₈₀ .

That is, the COM selection switch circuits CSW ₁ and CSW ₂ select the drive signal COM 3, and the COM selection switch circuit CSW ₁₈₀ selects the drive signal COM ₁ and outputs the drive signals V _{1 to} V ₁₈₀ to the switching circuit 40. At this time, the ground line _{G 1} and _{G 2} is connected to the ground GND3, ground line _{G 180} is connected to the ground GND1.

At time T7, the latch circuit 52 of the switching circuit 50, in synchronization with the rise of the latch signal LT, latches the SIH data _(SIH 1 _{~SIH 180)} and SIL data _(SIL 1 _{~SIL 180),} a latch signal At time T8 when the fall of LT occurs, each SIH data (SIH _{1 to} SIH ₁₈₀ ) and SIL data (SIL _{1 to} SIL ₁₈₀ ) are output to the OR circuits OR _{1 to} OR ₁₈₀ collectively. Here, as shown in FIG. 9, data of (SIH ₁ , SIL ₁ ) = (1, 0) is input to the OR circuit OR _1, and data of (SIH ₂ , SIL ₂ ) = (1, 0) Is input to the OR circuit OR _2, and similarly, data of (SIH ₁₈₀ , SIL ₁₈₀ ) = (1, 0) is input to the OR circuit OR ₁₈₀ . That is, each of the OR circuits OR _{1 to} OR ₁₈₀ outputs the high level switching signals S _{1 to} S ₁₈₀ to the level shifter circuit 53, and the level shifter circuit 53 amplifies each of the switching signals S _{1 to} S ₁₈₀ and outputs each switching element. Output to SW _{1 to} SW ₁₈₀ .

As described above, at time T8, by the high level of the switching signal _S 1 _{to S 180} is input to each of the switching elements _SW 1 _{to SW 180,} the switching elements _SW 1 _{to SW 180} are turned on, COM selection The drive signals V _{1 to} V ₁₈₀ supplied from the circuit 40 are output to the corresponding piezoelectric elements PZ _{1 to} PZ ₁₈₀ . Thus, the piezoelectric elements PZ ₁ and PZ ₂ is supplied drive signal COM3, the piezoelectric elements _{PZ 180} is supplied drive signal COM1, the weight of the droplets color filter substrate P corresponding to each of the drive signals Discharged on top. By repeating the above operation for all positions on the color filter substrate P, a color filter layer is formed on all pixels on the color filter substrate P.

At time T9, data of (SIH ₁ , SIL ₁ ) = (0, 0) is input to the OR circuit OR _1, and data of (SIH ₂ , SIL ₂ ) = (0, 0) is OR circuit. is input to the OR _{2, likewise,} be because _{(SIH 180,} SIL 180) data = (0, 0) is input to the OR circuit _{OR 180,} all switching signals _S 1 _{to S 180} is the low level or less, Each of the switching elements SW _{1 to} SW ₁₈₀ is turned off. Therefore, in this case, the drive signal COM1~COM4 is supplied to the droplet discharge head 5, the drive signal _V 1 _{~V 180} for the piezoelectric elements _PZ 1 _{to PZ 180} is not supplied.

As described above, according to the droplet discharge device IJ, one of the drive signals COM1 to COM4 is selected and supplied to one electrode of each of the piezoelectric elements PZ _{1 to} PZ ₁₈₀ , and for each piezoelectric element. Since the ground of the D / A converter that generates the selected drive signal is connected to the other electrode of the piezoelectric element, even if a drive signal having a phase shift is supplied to each piezoelectric element, the sneak current Can be prevented. As a result, the drive waveform supplied to the piezoelectric element is not distorted, and the droplet discharge amount can be accurately controlled.

  In the color filter substrate P used for a liquid crystal display device or the like, since each pixel is regularly arranged in the X-axis direction and the Y-axis direction, the discharge data SIA and the COM selection data SIB to be used are one type. There are many. Therefore, in this case, the transfer of the discharge data SIA and the COM selection data SIB to the droplet discharge head 5 is performed only once, and the same discharge data SIA and COM selection data SIB are sent each time the droplet discharge head 5 is moved. It is preferable not to retransmit. For example, when a COMS-IC is used as a circuit component, the amount of heat generation increases depending on the transfer frequency. Therefore, when not necessary as described above, the amount of heat generation can be reduced by not retransmitting the ejection data SIA and the COM selection data SIB. Can be suppressed.

  In the above-described embodiment, one droplet discharge head 5 and one drive circuit substrate 30 corresponding to the droplet discharge head 5 have been described as examples. 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 eject droplets by changing the volume of the cavity 24 according to 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.

1 is a schematic configuration diagram of a droplet discharge device IJ according to an embodiment of the present invention. It is a detailed explanatory view of the droplet discharge head 5 in one embodiment of the present invention. FIG. 3 is a circuit configuration diagram of a droplet discharge head 5 and a drive circuit board 30 in an embodiment of the present invention. FIG. 6 is a variation distribution diagram of a droplet discharge amount of the droplet discharge head 5 in an embodiment of the present invention. It is explanatory drawing regarding the setting method of COM selection data SIB in one Embodiment of this invention. It is an example of the waveform of the drive signals COM1-COM4 in one Embodiment of this invention. It is explanatory drawing which shows the example of a memory | storage of the drive waveform data of the drive signals COM1-COM4 in one Embodiment of this invention. FIG. 4 is a detailed explanatory diagram of a COM selection circuit 40 and a switching circuit 50 of the droplet discharge head 5 according to an embodiment of the present invention. It is a 1st timing chart which shows operation | movement of the droplet discharge apparatus IJ in one Embodiment of this invention. It is a 2nd timing chart which shows operation | movement of the droplet discharge apparatus IJ in one Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS IJ ... Droplet discharge apparatus, 1 ... Apparatus stand, 2 ... Work stage, 3 ... Stage moving apparatus, 4 ... Carriage, 5 ... Droplet discharge head, 6 ... Carriage transfer apparatus, 7 ... Tube, 8 ... 1st tank, DESCRIPTION OF SYMBOLS 9 ... 2nd tank, 10 ... 3rd tank, 11 ... Control apparatus, 30 ... Drive circuit board, 31 ... Interface, 32 ... Drawing data memory, 33 ... Address conversion circuit, 34 ... 1st drive waveform memory, 35 ... Second drive waveform memory, 36 ... first D / A converter, 37 ... second D / A converter, 38 ... third D / A converter, 39 ... fourth D / A converter, N ₁ to N ₁₈₀ ... Nozzle, PZ _{1 to} PZ ₁₈₀ ... Piezoelectric element, 40 ... COM selection circuit, 50 ... Switching circuit

Claims (5)

A droplet discharge head having a plurality of nozzles and driving elements provided corresponding to the nozzles;
A droplet discharge apparatus comprising: a plurality of drive signal generating units that respectively generate a plurality of types of drive signals; and a drive signal selection unit that selects and supplies one of the plurality of types of drive signals for each drive element. Because
The drive signal selection means selects one of the plurality of types of drive signals and supplies it to one electrode of the drive element, and also generates a ground of the drive signal generation means for generating the selected drive signal and the ground A droplet discharge device, wherein the other electrode of the drive element is connected. The drive signal selection means includes
Input terminals corresponding to each type of drive signal;
A first ground terminal connected to the ground of the drive signal generating means for generating each type of drive signal;
An output terminal for outputting the selected drive signal;
A second ground terminal connected to the other electrode of the drive element,
The input terminal corresponding to the selected drive signal and the output terminal are connected, and the first ground terminal and the second ground terminal are connected to the ground of the drive signal generating means for generating the selected drive signal. The droplet discharge device according to claim 1, wherein the droplet discharge device is connected. The drive signal selection means is provided in the droplet discharge head,
The liquid droplet ejection apparatus according to claim 1, further comprising a drive circuit board provided with the drive signal generation unit.   The liquid droplet ejection apparatus according to claim 1, wherein the driving element is a piezoelectric element. A droplet discharge head having a plurality of nozzles and driving elements provided corresponding to the nozzles;
A method for driving a droplet discharge device, comprising a plurality of drive signal generating means for generating a plurality of types of drive signals, and selecting and supplying one of the plurality of types of drive signals for each drive element. And
One of the plurality of types of driving signals is selected and supplied to one electrode of the driving element, and a ground of driving signal generating means for generating the selected driving signal and the other electrode of the driving element are provided. A method for driving a droplet discharge device, comprising: connecting.

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