JP2009190228A - Drive method of liquid droplet discharge head, and thin film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniform a discharge amount while using a liquid droplet discharge head of a simple configuration. <P>SOLUTION: In the driving method of the liquid droplet discharge head, the liquid droplet discharge head is provided with a plurality of discharge units discharging a liquid body. In a sequence in which discharge amounts obtained by driving the plurality of discharge units by predetermined driving signals are arranged in order of their magnitude, each of a plurality of groups is constituted of discharge units corresponding to continued elements, the plurality of discharge units are divided into a plurality of groups G1 to G4 by using weighted averages based on discharge amounts of the plurality of discharge units, a plurality of driving signals adjusted for each group of the plurality of groups G1 to G4 are selected and supplied to the plurality of discharge units so that statistics of discharge amounts obtained by performing driving by the predetermined driving signals in each of the plurality of group G1 to G4 are brought close to a setting value of the discharge amount. Thus the discharge units are driven. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for driving a droplet discharge head and a method for forming a thin film.

  In recent years, a film forming technique using a droplet discharge method has attracted attention. According to the droplet discharge method, it is possible to dispose a minute liquid containing a film forming material at a desired position. Thereby, a fine film pattern can be formed, and patterning is facilitated as compared with the case of using a photolithography method. In addition, since the waste of the film forming material can be reduced, the manufacturing cost can be reduced.

  A droplet discharge head used in the droplet discharge method includes, for example, a large number of discharge units arranged in the Y direction. Each discharge unit includes a liquid storage unit, a nozzle, a piezoelectric element that pressurizes the liquid and pushes it out of the nozzle. The liquid material is disposed by discharging the liquid material from the discharge unit while scanning the film formation surface in the X direction with such a droplet discharge head.

  In the droplet discharge head, it is important to make the discharge amount of the liquid material uniform in the plurality of discharge units. This is because if the discharge amount varies, the film thickness varies in the Y direction. For example, when a film thickness variation occurs in the color filter of the image display device, this is recognized as a streak (straight line) along the X direction, and the display quality is impaired.

In order to reduce the variation in the discharge amount, it is conceivable to apply the method disclosed in Patent Document 1. In Patent Document 1, in an ink jet recording head (printer), the size (ejection amount) of a recording dot is made variable by selecting an actuator driving voltage waveform from a plurality of types.
JP-A-9-17483

  If the method of patent document 1 is applied, by supplying individually the drive signal which adjusted the voltage value etc. for each discharge unit, each discharge amount can be adjusted and discharge amount can be equalized. it is conceivable that. However, if such a technique is applied as it is, the following inconvenience may occur.

  Usually, the droplet discharge head includes a large number of discharge units, and it is necessary to provide a large number of drive circuits such as a drive waveform generation circuit if a drive signal is prepared and supplied to each. Therefore, inconveniences such as an increase in size of the device, an increase in device cost, and an increase in power consumption occur. In addition, when a large number of drive circuits are used, the electrical characteristics vary, and thus the ejection amount varies due to the drive circuits. Therefore, if uniform electrical characteristics are to be achieved, advanced processing is required for manufacturing the drive circuit, which may cause inconveniences such as an increase in manufacturing cost or a decrease in yield.

  The present invention has been made in view of the above circumstances, and provides a driving method of a droplet discharge head capable of discharging a uniform amount of liquid while using a droplet discharge head having a simple configuration. This is one of the purposes. Another object of the present invention is to provide a thin film forming method capable of obtaining a thin film having a uniform thickness.

  The droplet ejection head driving method of the present invention is a droplet ejection head driving method including a plurality of ejection units for ejecting a liquid material, and the ejection amount obtained by driving the plurality of ejection units with a predetermined drive signal. Forming each of the plurality of groups with discharge units corresponding to consecutive elements in a number sequence arranged in size order, and using the weighted average based on the discharge amount of the plurality of discharge units, the plurality of discharge units A plurality of drive signals that are divided into a plurality of groups and adjusted for each of the plurality of groups so that a statistical value of the discharge amount driven by the predetermined drive signal in each of the plurality of groups approaches a set value of the discharge amount The plurality of discharge units are selected and supplied to drive the discharge units.

  In this way, since the plurality of discharge units are divided into a plurality of groups using a weighted average based on the discharge amounts of the plurality of discharge units, the load on the side that drives each group can be made uniform. In addition, since a plurality of drive signals adjusted for each of a plurality of groups are used so that the statistical value of the discharge amount driven by a predetermined drive signal approaches the discharge amount set value, the discharge amount of the plurality of discharge units is set to the set value. The discharge amount is made uniform. In addition, since a plurality of drive signals adjusted for each of a plurality of groups are selected and supplied to a plurality of discharge units to drive the discharge units, each of the plurality of discharge units is provided with a drive circuit or the like to be driven independently As a result, the number of circuits for generating drive signals can be reduced. As described above, according to the present invention, it is possible to reduce variation in the discharge amount among a plurality of discharge units while using a droplet discharge head having a simple configuration.

  The weighted average based on the discharge amount is an average weighted by a statistical value calculated from the discharge amount. For example, the total discharge amount (statistical value) of the discharge unit divided by the number of groups, For example, the total difference (statistical value) between the discharge amount and the reference value divided by the number of groups. The gist of the present invention is to group the statistical values for ejection in the group so as to be the weighted average.

  The thin film forming method of the present invention is a thin film forming method for forming a thin film by using a droplet discharge head provided with a plurality of discharge units for discharging a liquid material containing a thin film forming material, the plurality of discharge units. And a plurality of the discharge units based on the inspection result of the inspection step and the inspection step of inspecting the discharge amount of each of the discharged liquid bodies. An adjustment step of adjusting the predetermined drive signal for each of the plurality of groups, and driving the plurality of ejection units using the drive signal adjusted in the adjustment step. A thin film forming step of forming a thin film, wherein the adjusting step is a discharge unit corresponding to a continuous element in a number sequence in which discharge amounts based on the inspection result are arranged in order of size. Thereby constituting each of the number of groups, the total discharge amount of the discharge units included in each of the plurality of groups, characterized by divided into a plurality of groups so as to be substantially equal.

  In this way, since grouping is performed based on the total discharge amount of the discharge units included in each group, the discharge amounts of all discharge units included in each group can be reflected (influenced). In addition, since the total is grouped so as to be substantially equal, the total degree of influence exerted by the discharge amount of the discharge unit can be made uniform among a plurality of groups. In other words, since grouping is performed by the weighted average weighted by the discharge amount, the load on the side where the drive signal is supplied can be made uniform, and the discharge amount can be made uniform.

In addition, since each group is composed of discharge units corresponding to continuous elements in a number sequence in which the discharge amounts are arranged in order of size, the variation in the discharge amount in each group is more than the variation in the discharge amount in the plurality of discharge units as a whole. Becomes smaller. Accordingly, if the drive signal is adjusted for each group in the adjustment process so that the statistical value (for example, average value) of the discharge amount in each group approaches a predetermined value, the variation in the discharge amount among the plurality of discharge units is reduced. be able to.
As described above, according to the above method, the discharge amount can be made uniform by a plurality of discharge units, so that a uniform amount of liquid can be disposed, and a thin film having a uniform film thickness is formed. It becomes possible.

  Further, in the adjustment step, in the numerical sequence in which the discharge amounts based on the inspection results are arranged in order of magnitude, the order of the elements of the numerical sequence is X, the value of the element is Y, and the relationship between X and Y is expressed by a polynomial. It can be approximated and divided into a plurality of groups based on this polynomial. In this case, in the adjusting step, an area obtained by integrating Y in the range of X is calculated based on the polynomial, and a partial area is calculated by dividing the area by the number of the plurality of groups, and then the polynomial is calculated. After dividing the range of X into the number of the plurality of groups so that a value obtained by integrating Y based on the above becomes the partial area, each of the plurality of groups is configured by the discharge unit corresponding to the divided range of X It is preferable to do.

Thus, if the discharge amount is approximated by a polynomial, it is easy to consider the measurement error of each discharge unit. For example, the discharge amount can be appropriately evaluated by rounding the measurement error. Therefore, by dividing into groups based on such a polynomial, it becomes possible to divide a plurality of discharge units into appropriate groups.
Further, if the area obtained by integrating Y in the range of X in the above polynomial is calculated, the total discharge amount in the droplet discharge head can be calculated. If the partial area is calculated by dividing this area by the number of the plurality of groups, the total discharge amount for each group can be calculated. Therefore, it is possible to divide into appropriate groups by obtaining a range of X as a partial area and forming a group with the discharge units belonging to the range.

  The thin film forming method of the present invention is a thin film forming method for forming a thin film by using a droplet discharge head provided with a plurality of discharge units for discharging a liquid material containing a thin film forming material, the plurality of discharge units. And a plurality of the discharge units based on the inspection result of the inspection step and the inspection step of inspecting the discharge amount of each of the discharged liquid bodies. An adjustment step of adjusting the predetermined drive signal for each of the plurality of groups, and driving the plurality of ejection units using the drive signal adjusted in the adjustment step. A thin film forming step of forming a thin film, wherein the adjusting step is a discharge unit corresponding to a continuous element in a number sequence in which discharge amounts based on the inspection result are arranged in order of size. Each of the number groups, and comparing the change amount of the discharge amount on the large discharge amount side and the change amount of the discharge amount on the small side in the sequence, the side having the small change amount as a reference side, Dividing into a plurality of groups so that the sum of the difference between each value of the number sequence and the reference value is substantially equal, using the end value on the reference side of the number sequence as a reference value of the discharge amount .

  In this way, since the grouping is based on the sum of the difference between the discharge amount of the discharge unit and the reference value in the group, the difference between the discharge amount and the reference value in all the discharge units included in each group is reflected. (Influence). Further, since the sum of the difference between each value of the number sequence and the reference value is divided into a plurality of groups so as to be substantially equal, the number of discharge units constituting each group is on the side where the change amount is small (reference It increases in the group on the (side) side, and decreases in the group on the larger side. For example, the number of discharge units in the group with the larger change amount is smaller than when the groups are divided so that the number of discharge units in each group is equal. Therefore, the difference between the maximum value and the minimum value of the discharge amount in this group becomes small, and when the discharge unit of this group is driven by the adjusted drive signal, the discharge amount is more than in the case of grouping so that the number of discharge units is equal. Variation in quantity is reduced.

In addition, since grouping is performed based on a weighted average weighted by the difference between the discharge amount and the reference value, the load on the drive signal supply side can be made uniform, and the discharge amount can be made uniform.
As described above, according to the above method, it is possible to satisfactorily adjust the discharge amount of the discharge unit, to make the load on the side where the drive signal is supplied uniform, and to form a thin film having a uniform film thickness. It becomes possible.

  Hereinafter, although one embodiment of the present invention is described, the technical scope of the present invention is not limited to the following embodiment. In the following description, various structures are illustrated using the drawings. However, in order to make the characteristic portions of the structure easy to see, the dimensions and scale of the structure are illustrated as appropriately different from the actual structure. First, an example of a droplet discharge head used in the present invention will be described.

[Droplet ejection head]
FIGS. 1A to 1C are diagrams showing the configuration of the droplet discharge head 140 of this example. FIG. 1A is a plan view of nozzles provided in each discharge unit, FIG. 1B is an exploded perspective view showing the main part of the droplet discharge head 140, and FIG. 1C is a cross-section of each discharge unit. It is a block diagram.

As shown in FIG. 1A, the droplet discharge head 140 includes 180 discharge units U _{1 to} U ₁₈₀ arranged in a row, and corresponds to each of the discharge units U _{1 to} U _180. Nozzles N _{1 to} N ₁₈₀ are provided. As shown in FIG. 1B, the droplet discharge head 140 includes a vibration plate 141 and a nozzle plate 142 that are provided apart from each other, and a partition wall 144 that is provided by partitioning them. . A space partitioned by the partition wall 144 is a cavity 145, and one cavity 145 corresponds to one discharge unit. Corresponding to each of the discharge units U _{1 to} U ₁₈₀ , nozzles N _{1 to} N ₁₈₀ are provided on the nozzle plate 142, and piezoelectric elements (drive elements) PZ _{1 to} PZ ₁₈₀ are provided on the vibration plate 141. ing. The piezoelectric elements PZ _{1 to} PZ ₁₈₀ are, for example, piezoelectric elements.

  The plurality of cavities 145 communicate with a common liquid reservoir 143 through supply holes 145a corresponding to the cavities 145, respectively. The diaphragm 141 is provided with an inlet 141a corresponding to the liquid reservoir 143, and a tube (not shown) for supplying a liquid material is connected to the inlet 141a. With such a configuration, the liquid material supplied from the tube is stored in the liquid reservoir 143 through the introduction port 141a, and further filled into each cavity 145 through the supply hole 145a.

As shown in FIG. 1 (c), the piezoelectric elements PZ ₁ includes a piezoelectric material 146, and a pair of electrodes 147 that sandwich it. A drive circuit board (described later) for supplying drive signals to the piezoelectric elements PZ _{1 to} PZ ₁₈₀ is provided corresponding to the droplet discharge head 140. This drive circuit board is connected to a control device (not shown), and selects a drive voltage waveform that is actually supplied to the piezoelectric elements PZ _{1 to} PZ ₁₈₀ based on drawing data and control signals input from the control device. , Drive signal generation, ejection timing control, and the like.

When a drive signal is supplied from the drive circuit board, a voltage is applied between the pair of electrodes 147, and the piezoelectric material 146 contracts by a strain amount corresponding to the voltage value. Then, the vibration plate 141 in the arrangement portion of the piezoelectric element PZ ₁ is flexed outwardly (opposite to the cavity 145) integral with the piezoelectric element PZ _1. As a result, the volume of the cavity 145 increases, and the increased volume of the liquid material flows from the liquid pool 143 into the cavity 145.

When the application of the voltage between the pair of electrodes 147 is stopped, the piezoelectric elements PZ ₁ and the vibrating plate 141 both return to their original shapes, the cavity 145 is returned to the original volume. Then, increases the pressure in the liquid material in the cavity 145, the droplet L of the liquid toward a substrate (not shown) is ejected from the nozzle N _1. The discharge amount of the liquid material, that is, the volume of the droplet L is based on the volume change amount of the cavity 145 and can be adjusted by the voltage value applied between the pair of electrodes 147.

Such adjustment of the discharge amount can theoretically be performed individually for the discharge units U _{1 to} U ₁₈₀ . However, in this case, since there are 180 control systems for each discharge unit, inconveniences such as high cost of the apparatus and large size of the apparatus occur. In the droplet discharge head 140 of this example, the discharge units U _{1 to} U ₁₈₀ are divided into a plurality of groups, and the discharge amount can be adjusted for each group. Next, a first embodiment of a droplet ejection head driving method according to the present invention will be described.

[First Embodiment]
FIG. 2 is a schematic diagram showing the circuit configuration of the droplet discharge head 140 and the drive circuit board 200. As shown in FIG. 2, the drive circuit board 200 includes an interface 210, a drawing data memory 220, a waveform selection circuit 230, and first to fourth D / A converters 240A to 240D. The droplet discharge head 140 includes a COM selection circuit 170, a switching circuit 180, and a piezoelectric element group 190 including the piezoelectric elements PZ _{1 to} PZ ₁₈₀ . In the droplet discharge head 140, the discharge units U _{1 to} U ₁₈₀ are divided into four groups, and a common drive signal is supplied to each group.

  The interface 210 is connected to the control device via a PCI bus or the like (not shown). The control device outputs drawing data SI including ejection data SIA and COM selection data SIB, various control signals such as a clock signal and a latch signal for driving and controlling the circuit, and the like. The drawing data SI and various control signals are written in the drawing data memory 220. The drawing data memory 220 is, for example, a 32-bit SRAM.

The ejection data SIA is data defining whether or not to supply a drive signal to each of the ejection units U _{1 to} U ₁₈₀ according to the position of the droplet ejection head 140. For example, the thin film pattern to be formed is divided into a matrix, and the bitmap data is obtained by mapping on / off of the discharge operation in each divided bit by binary data.

  The COM selection data SIB is data defining the grouping of the discharge units and the drive signal supplied to each group. Here, one of four types of drive signals COM1 to COM4 is selected as the drive signal for each discharge unit. The COM selection data SIB includes drive waveform number data WN that defines the waveforms of the drive signals COM1 to COM4 and data that defines which of the drive signals COM1 to 4 is selected for each ejection unit.

  The drawing data memory 220 outputs ejection data SIA as serial data to the switching circuit 180 of the droplet ejection head 140 in response to data read requests by various control signals, and ejects droplets as COM selection data SIB as serial data. The data is output to the COM selection circuit 170 of the head 140. The drive waveform number data WN is output to the waveform selection circuit 230.

  The waveform selection circuit 230 reads the waveform data specified by the drive waveform number data WN from the waveform data (for example, 64 types) stored in advance, and stores it in the address corresponding to the ejection data SIA. Further, in response to a data read request by various control signals, the drive waveform data stored in the designated address is output to each D / A converter.

  The first D / A converter 240A holds drive waveform data input from the waveform selection circuit 230 in synchronization with various control signals. Further, the drive waveform data is converted into an analog signal to generate a drive signal COM1 and output to the COM selection circuit 170 of the droplet discharge head 140. Similarly, the second D / A converter 240B generates the drive signal COM2, the third D / A converter 240C generates the control signal COM3, and the fourth D / A converter 240D generates the drive signal COM4. The data is output to the COM selection circuit 170.

The COM selection circuit 170 is controlled by various control signals, and outputs each of the piezoelectric element drive signals V _{1 to} V ₁₈₀ to the switching circuit 180 based on the COM selection data SIB. The switching circuit 180 is controlled by various control signals, and turns on / off the drive signals V _{1 to} V ₁₈₀ for each discharge unit based on the discharge data SIA. Thereby, a predetermined drive signal is supplied to a predetermined piezoelectric element among the piezoelectric elements PZ _{1 to} PZ ₁₈₀ provided corresponding to each discharge unit. The piezoelectric element to which the drive signal is supplied discharges a liquid material having a discharge amount corresponding to the voltage value applied between the pair of electrodes 147 as described above.

Next, the drive signal setting method of the present embodiment will be described with reference to FIGS. FIG. 3 is a graph showing an example of the distribution of the discharge amount of the discharge unit. In FIG. 3, the horizontal axis indicates the number of each discharge unit, and the vertical axis indicates the discharge amount. In addition, although the discharge amount of each discharge unit is discrete data, FIG. 3 shows the discrete data connected by a smooth line. Further, among the discharge units U _{1 to} U ₁₈₀ arranged in a row, those arranged on both ends may have a discharge amount that is much larger than that arranged on the center side. Here, from the viewpoint of making the discharge amount uniform, the discharge units U _{1 to} U ₁₀ and U _{171 to} U ₁₈₀ arranged on both ends are not used. Hereinafter, the discharge units U _{11 to} U ₁₇₀ to be used are grouped.

  FIG. 4 is an explanatory diagram of a grouping method. The discharge amount shown in FIG. 4 is a graph in which the discharge amounts in FIG. 3 are rearranged in order of size. In FIG. 4, the horizontal axis indicates the order of elements (element number X) in a numerical sequence in which the discharge amounts are arranged in order of magnitude, and the vertical axis indicates the discharge amount Y. In the present invention, each group is constituted by the discharge units corresponding to the continuous elements in the above-mentioned several sequences. Here, the grouping is performed so that the total discharge amount in each group is substantially equal.

  Examples of the grouping method include a method of using discrete discharge amount data as it is, a method of approximating the discharge amount shown in FIG. When using discrete data, for example, the total discharge amount of 160 discharge units to be used is calculated, and this is divided by the number of groups, whereby the total discharge amount in each group can be obtained. The element number X corresponding to each group can be obtained by adding the discharge amount Y in order from the largest or smallest value of the elements in the sequence and repeating this until the total of the discharge amount of each group is reached. it can. Note that when the discharge amount Y is added as described above, the sum may not be equal to the total discharge amount. In this case, it is possible to appropriately select to which group the boundary elements that are equally divided into the total discharge amount belong. For example, when the boundary elements belong to different groups, the total discharge amount can be divided into substantially equal groups by evaluating the total discharge amount in the group by a least square method or the like.

  In this embodiment, the discharge amount is approximated by a polynomial, and grouping is performed using this polynomial. Specifically, first, the discharge amount Y shown in FIG. 4 is approximated by a polynomial Y of X = f (X). Then, by integrating Y in the range of 11 ≦ X ≦ 170 using this polynomial, the area surrounded by the X axis and Y = f (X), that is, the total discharge amount of 160 discharge units to be used is obtained. calculate. Then, by dividing this total discharge amount by the number of groups, the total discharge amount (partial area) in each group is obtained. If an approximate expression is used, the measurement error of the discharge amount can be rounded off, and adverse effects due to abnormal values or the like can be reduced. Then, an interval of X to be integrated is obtained so that a value obtained by integrating Y becomes the partial area.

Thereby, the section of X corresponding to each group can be defined. If approximated by a polynomial, the approximate expression can be analytically integrated, so calculation of the X section corresponding to each group is facilitated. Further, even when the approximate expression is used, it can be divided into substantially equal groups in the same manner as when discrete data is used, and the discharge units U _{1 to} U ₁₈₀ are thus divided into groups G ₁ to G 4.

Next, as shown in FIG. 5, the drive signals COM1 to COM4 are adjusted for each of the groups G1 to G4. Here, based on the relational expression of the discharge amount with respect to the voltage applied to the piezoelectric element of the discharge unit, a voltage (corrected drive voltage) that provides a predetermined discharge amount is calculated. The formula for obtaining the correction drive voltage is expressed by the following formula (1), for example. In Expression (1), V0 is an applied voltage before correction, and K is a coefficient obtained in advance through experiments or the like. Further, in the formula (1), the statistical value “group center weight” may be replaced with the statistical value “average discharge unit weight in each group”. Accordingly, a drive signal (for example, COM4) having a low voltage is set for a group having a large discharge amount (for example, group G4), and a drive signal having a low voltage (for example, COM1) is set for a group having a small discharge amount (for example, group G1). ) Is set. Thereby, the discharge amount is made uniform.
Corrected drive voltage = V0−K. (Center weight of range−appropriate weight) (1)

  FIG. 6 is a graph showing a comparison of the distribution of the ejection amount (before correction) by a predetermined drive signal and the distribution of the ejection amount (after correction) by the control signals COM1 to COM4. As shown in FIG. 9, after the correction, the variation in the discharge amount is significantly reduced after the correction. Thus, since the droplet discharge head 140 can select and supply a drive signal for each discharge unit, the discharge amount of each discharge unit can be adjusted by adjusting the drive signal. It is possible to reduce variation in the discharge amount among a plurality of discharge units.

  In the liquid droplet ejection head driving method of the present embodiment, the ejection amount can be adjusted for each of the groups G1 to G4. Therefore, the configuration is simpler than that for adjusting the ejection amount for each ejection unit. A droplet discharge head can be obtained. In addition, since the weighted average based on the discharge amount is used for grouping, the electrical load on the drive signal supply side, for example, the first to fourth D / A converters 240A to 240D is made uniform. The discharge amount can be made uniform.

In order to reduce the variation in the discharge amount by the conventional driving method, high-precision processing is required for manufacturing the droplet discharge head so that the characteristic variation in the plurality of discharge units is reduced. Therefore, inconveniences such as an increase in cost of the droplet discharge head and a decrease in yield have occurred.
According to the present invention, the discharge amount can be made uniform by adjusting the drive signal, so that a processing error or the like allowed for the droplet discharge head increases. Therefore, the manufacturing cost of the droplet discharge head can be reduced, the process of selecting the droplet discharge head can be simplified or omitted, and the yield of the droplet discharge head can be improved.

[Second Embodiment]
Next, a second embodiment of the droplet ejection head driving method according to the present invention will be described. The present embodiment is different from the first embodiment in that grouping is performed using a weighted average weighted by a difference between a discharge amount by a predetermined drive signal and a discharge amount of a reference value.

  7 and 8 are explanatory diagrams showing a grouping method according to this embodiment. 7 and 8 are graphs in which the discharge amounts are rearranged in order of magnitude, the discharge amount shown in FIG. 7 is convex downward, and the discharge amount shown in FIG. It is convex. In this embodiment, first, the change amount of the discharge amount on the side with a large discharge amount is compared with the change amount of the discharge amount on the small side, and the side with the small change amount is set as a reference side. For example, the discharge amount Y is approximated by a polynomial Y of X = f (X) and differentiated, and the differential coefficient is compared on the side where the discharge amount is large (the side where X is small) and the side where X is small (the side where X is large). By doing so, the reference side is determined. When Y = f (X) is convex downward as shown in FIG. 7, the side where X is large is the reference side, and when Y = f (X) is convex upward as shown in FIG. The smaller side is the reference side.

  Then, in the numerical sequence in which the discharge amounts are rearranged in order of magnitude, the value (discharge amount) of the element located at the reference end is set as the reference value. In FIG. 7, Y at X = 170 is a reference value, and in FIG. 7, Y at X = 11 is a reference value. Then, grouping is performed so that the sum of the difference between the value of each element and the reference value is substantially equal. For grouping, as in the first embodiment, discrete data may be used as is, or an approximate expression may be used. In the case where the approximate expression is used, grouping may be performed so that the partial area of the portion surrounded by the reference value and Y = f (X) is substantially equal. In this way, since grouping is performed using a weighted average, it is possible to equalize the electrical load on the side where the drive signal is supplied, and to group according to the amount of change in the ejection amount.

  For example, in the group shown in FIG. 7, in the group G4 where the change amount of the discharge amount is large, the number of discharge units (section X) is smaller (narrower) than in the group G1 where the change amount is small. Therefore, the difference between the maximum value and the minimum value of the discharge amount in the group is smaller than in the case of grouping so that the number of discharge units is uniform. Therefore, by adjusting the drive signal for each group, it is possible to reduce the variation in the discharge amount even in the entire droplet discharge head. In the case shown in FIG. 8, the variation in the discharge amount can be reduced for the same reason.

[Thin film formation method]
Next, an embodiment of the thin film forming method of the present invention will be described. The present embodiment is an example in which the thin film forming method of the present invention is applied to the formation of a color filter layer.
First, the discharge amount of each of the discharge units U _{1 to} U ₁₈₀ when driven by a predetermined drive signal is inspected using a known method (inspection process). For example, a liquid material containing a color filter material is supplied to the droplet discharge head 140, and the droplet discharge head 140 is disposed above the inspection substrate. Then, the same drive voltage waveform (for example, drive signal COM1) is supplied to the discharge units U _{1 to} U ₁₈₀ , and the liquid material from each discharge unit is placed on the inspection substrate. Then, the volume of each liquid material arranged by a vertical scanning optical interference method or the like is measured. Thereby, the discharge amount of the discharge unit _U 1 _{~U 180} is obtained.

Next, as described in the first embodiment and the second embodiment, the discharge units U _{11 to} U ₁₇₀ are divided into groups G 1 to G 4 based on the discharge amount obtained in the inspection process. Then, the drive signals COM1 to COM4 are set based on the statistical values of the discharge amounts in the groups G1 to G4. Thereby, the discharge amount is made uniform as shown in FIG.

For example, in the scanning direction orthogonal to the arrangement direction of the discharge units U _{1 to} U ₁₈₀ (see FIG. 1A), discharge is performed while changing the relative position between the color filter substrate (not shown) and the droplet discharge head. The liquid material is discharged from the units U _{11 to} U ₁₇₀ . Thereby, the liquid material can be arranged at a predetermined position of the color filter substrate. And the color filter layer (thin film) is obtained by solidifying the arrange | positioned liquid body by a drying process etc. FIG.

  In the thin film forming method of the present invention as described above, since the discharge units are divided into appropriate groups, variations in the discharge amount can be significantly reduced. Therefore, a predetermined amount of liquid material can be disposed, and a thin film having a uniform thickness can be formed. For example, if the present invention is applied to the formation of a color filter layer, a color filter layer having a uniform film thickness can be formed. Therefore, the color filter layer can be made to function without causing unevenness and the like, and the display quality of the image display apparatus provided with this can be improved.

(A)-(c) is a figure which shows the structural example of a droplet discharge head. It is a schematic diagram showing a droplet discharge head and a drive circuit board circuit configuration. It is a graph which shows an example of distribution of discharge amount. It is explanatory drawing of the method of grouping based on this invention. It is a graph which shows an example of a drive signal. It is a graph which shows the comparison of the distribution of the discharge amount before correction | amendment and after correction | amendment. It is explanatory drawing of the method of grouping different from FIG. It is explanatory drawing of the method of grouping different from FIG.

Explanation of symbols

140: droplet discharge head, 147: piezoelectric element (drive element), 200: drive circuit board, 230 ... waveform selection circuit, 170 ... COM selection circuit, COM1 to COM4 ... drive signal, G1 to G4 · · · _group, N _{1 ~N 180} ··· _nozzle, U _{1 ~U 180} ··· discharge unit

Claims (5)

A method of driving a droplet discharge head comprising a plurality of discharge units for discharging a liquid material,
Each of the plurality of groups is composed of discharge units corresponding to consecutive elements in a number sequence in which discharge amounts obtained by driving the plurality of discharge units with a predetermined drive signal are arranged in order of size, and discharge amounts of the plurality of discharge units The plurality of discharge units are divided into the plurality of groups using a weighted average based on the above, and the statistical value of the discharge amount driven by the predetermined drive signal in each of the plurality of groups is brought close to the set value of the discharge amount A driving method of a droplet discharge head, wherein a plurality of drive signals adjusted for each of the plurality of groups are selected and supplied to the plurality of discharge units to drive the discharge units. A thin film forming method for forming a thin film using a droplet discharge head including a plurality of discharge units for discharging a liquid material containing a thin film forming material,
An inspection step of driving the plurality of discharge units with a predetermined drive signal to discharge the liquid material, and inspecting each discharge amount of the discharged liquid material;
An adjustment step of dividing the plurality of ejection units into a plurality of groups based on the inspection result of the inspection step, and adjusting the predetermined drive signal for each of the plurality of groups;
A thin film forming step of driving the plurality of ejection units using the drive signal adjusted in the adjustment step to dispose the liquid material and forming a thin film;
In the adjusting step, each of the plurality of groups is configured by a discharge unit corresponding to a continuous element in a numerical sequence in which discharge amounts based on the inspection result are arranged in order of size, and the discharge included in each of the plurality of groups A thin film forming method, wherein the total discharge amount of the unit is divided into a plurality of groups so as to be substantially uniform.   In the adjustment step, in the numerical sequence in which the discharge amounts based on the inspection results are arranged in order of magnitude, the order of the elements of the numerical sequence is X and the value of the element is Y, and the relationship between X and Y is approximated by a polynomial. The thin film forming method according to claim 2, wherein the thin film is divided into the plurality of groups based on the polynomial.   In the adjusting step, an area obtained by integrating Y in the range of X based on the polynomial is calculated, a partial area is calculated by dividing the area by the number of the plurality of groups, and then Y is integrated based on the polynomial. After dividing the range of X into the number of the plurality of groups so that the obtained value becomes the partial area, each of the plurality of groups is configured by a discharge unit corresponding to the divided range of X. The thin film forming method according to claim 3. A thin film forming method for forming a thin film using a droplet discharge head including a plurality of discharge units for discharging a liquid material containing a thin film forming material,
An inspection step of driving the plurality of discharge units with a predetermined drive signal to discharge the liquid material, and inspecting each discharge amount of the discharged liquid material;
An adjustment step of dividing the plurality of ejection units into a plurality of groups based on the inspection result of the inspection step, and adjusting the predetermined drive signal for each of the plurality of groups;
A thin film forming step of driving the plurality of ejection units using the drive signal adjusted in the adjustment step to dispose the liquid material and forming a thin film;
In the adjusting step, each of the plurality of groups is configured by a discharge unit corresponding to a continuous element in a number sequence in which the discharge amount based on the inspection result is arranged in order of magnitude, and discharge is performed on the side where the discharge amount is large in the number sequence. The change amount of the amount is compared with the change amount of the discharge amount on the small side, the side with the small change amount is set as the reference side, and the end value on the reference side of the sequence is set as the reference value of the discharge amount. A method of forming a thin film, characterized in that the thin film is divided into a plurality of groups so that the sum of the difference between each value and the reference value is substantially equal.

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