JP2010012368A - Liquid jetting apparatus, apparatus of manufacturing flat panel display, flat panel display, apparatus of manufacturing solar cell panel, and solar cell panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To eliminate dispersion in an impact location of ink, thereby improving yield even if voltage characteristics disperse due to a piezoelectric element. <P>SOLUTION: A liquid jetting apparatus includes nozzles 40 arranged in an inkjet head 30 having a chamber 41 with a liquid nozzle hole 45 that fills an ink at its tip and the piezoelectric element 42 provided in the chamber 41, and configured to jet the ink from the hole 45 by varying a volume of the chamber 41 by applying voltage to the element 42; a velocity measuring section 62 that individually measures flying velocities of ink liquid droplets jetted from each nozzle 45 for every ink liquid droplet; and a voltage setting section 64 that individually varies and controls application voltages to the element 42 for every nozzle 40 based on the measured flying velocity for every ink liquid droplet. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus that ejects liquid toward a substrate, a flat panel display manufacturing apparatus to which the liquid ejecting apparatus is applied, a flat panel display manufactured by the flat panel display manufacturing apparatus, and the liquid ejecting apparatus. The present invention relates to a solar cell panel manufacturing apparatus to which is applied and a solar cell panel manufactured by the solar cell panel manufacturing apparatus.

  A liquid crystal display as a flat panel display is composed of a TFT substrate made of a transparent thin plate such as glass and a color filter substrate, and a minute gap called a cell gap is formed between the TFT substrate and the color filter substrate. Is formed. The cell gap is secured by a spacer made of an aggregate of a plurality of spacer beads, and liquid crystal is sealed in this space. The spacer is composed of spherical fine particles having a particle diameter of 3 to 5 μm, and a large number of spacers are dispersed on either the TFT substrate or the color filter substrate.

The spacers are arranged in a grid pattern in the black matrix region on the substrate. For this purpose, spacer ink made of a liquid in which spacer beads are uniformly dispersed in a solvent is used to spray the spacer ink so as to land on the black matrix region. As a method for supplying the spacer ink, an ink jet method as in Patent Document 1 is adopted. In this ink jet method, a droplet of spacer ink is ejected from each nozzle toward the substrate using an ink jet head in which a plurality of minute nozzles are arranged in a row. The ink jet head is disposed on the upper part of the transport table, and the ink jet head is disposed orthogonally or obliquely to the transport direction of the substrate. While the substrate is mounted on the transfer table and intermittently fed in one direction, ink is sprayed from the nozzles of the inkjet head toward the substrate in accordance with the intermittent feed timing.
JP 2007-025334 A

  The ink ejected from the inkjet head is a mixture of spacer beads for forming a cell gap, and must be landed accurately at a predetermined position on the substrate. The reason why the ink is accurately landed on the substrate is to form an appropriate cell gap between the TFT substrate and the color filter substrate in a lattice shape. If the ink landing position is inappropriate, the cell gap This is because the array cell substrate formed by bonding the TFT substrate and the color filter substrate becomes a defective product.

  The ink ejected from each nozzle of the ink jet head at the same timing must fly downward at a uniform speed. This is because if the flying speed becomes uneven, the ink ejected from each nozzle does not land on the substrate at the same timing. Here, since the substrate is intermittently conveyed in one direction, the substrate is temporarily stopped. Since ink is ejected from each nozzle in synchronization with the intermittent transport timing, if the substrate stop time is sufficiently secured, even if there is some variation in the ink landing timing, Does not significantly affect the error. However, recent flat panel displays are highly demanded to improve production efficiency, and must be terminated within a very short time for ink spraying. For this reason, the stop time of the substrate is limited to a short time, and a large landing error occurs in the transport direction of the substrate due to variations in the landing timing of the ink.

  Here, each nozzle of the ink jet head includes a chamber for filling ink and a piezoelectric element (piezo element) for pressurizing the ink in the chamber. This piezoelectric element is composed of a piezoelectric material such as ceramic sandwiched between two electrode plates, and the capacitance changes depending on the thickness of the piezoelectric material and the electrode plate. The size of each piezoelectric element is very small, and a slight error in processing accuracy of the piezoelectric material or the electrode plate greatly affects the capacitance of the piezoelectric element. As a result, individual differences are caused by the piezoelectric elements, so that the piezoelectric characteristics (piezoelectric effect) also vary. Due to variations in the piezoelectric characteristics, the pressure acting on the ink in the chamber varies depending on the piezoelectric element, and the flying speed of the ink ejected from the nozzles becomes non-uniform. For this reason, the landing timing of the ink on the substrate varies, and an error occurs in the landing position of the ink. This substrate becomes a defective product that cannot be used as a product, resulting in a decrease in yield.

  Accordingly, an object of the present invention is to eliminate variations in ink landing positions and improve yields even when the piezoelectric characteristics vary depending on the piezoelectric elements.

  According to a first aspect of the present invention, the liquid ejecting apparatus ejects the liquid from an ejecting head provided with an array of ejecting units that eject the liquid containing fine particles toward the substrate while the substrate is being transported. In the ejection device, the ejection unit includes a chamber for filling a liquid having a liquid ejection port at a tip and a piezoelectric element provided in the chamber, and applies a voltage to the piezoelectric element. By changing the volume of the chamber to cause the liquid to be ejected from the ejection port, and a speed measuring unit that individually measures the flying speed of the liquid ejected from each ejection unit for each liquid And a voltage setting unit that performs control to individually change the voltage applied to the piezoelectric element for each ejection unit based on the measured flying speed for each liquid. .

  According to this liquid ejecting apparatus, even if the piezoelectric characteristics of the piezoelectric elements vary, the applied voltage is individually changed for each ejecting unit according to the liquid flying speed, so that the liquid flying speed is made uniform. The liquid can be landed on the substrate at the same time.

  A liquid ejecting apparatus according to a second aspect of the present invention is the liquid ejecting apparatus according to the first aspect, wherein the photographing section captures an image that includes at least two liquids in flight ejected from one ejecting section. The speed measurement unit calculates the speed of the liquid based on a distance between two liquids included in an image captured by the imaging unit.

  According to the liquid ejecting apparatus, an image including two or more liquids in flight is acquired. Since the liquid is ejected from the ejection unit at a timing synchronized with the substrate transport speed, the pitch time for ejecting the liquid is constant. Then, the flying speed of the liquid can be calculated based on the distance between the two liquids in flight and the pitch time.

  The liquid ejecting apparatus according to a third aspect of the present invention is the liquid ejecting apparatus according to the second aspect, wherein the liquid display screen displays the liquid contained in the image, and the voltage displays the voltage applied to the piezoelectric element for each ejection section. A screen for displaying a setting screen, and an input unit for operating the contents displayed on the screen, and the liquid display screen is selected from among the liquids by operating the input unit. One liquid can be selected, and the voltage setting screen can change the applied voltage for each ejection unit by operating the input unit, and can be displayed on the liquid display screen. When one of the liquids is selected, an applied voltage of the ejection unit corresponding to the selected liquid among the ejection units displayed on the voltage setting screen is selected.

  According to this liquid ejecting apparatus, when it is recognized that the interval of the liquid ejected from one ejecting unit among the ejecting units displayed on the liquid display screen is abnormal, the ejecting unit is selected on the liquid display screen. For example, one injection unit among a large number of injection units displayed on the voltage setting screen is automatically selected. For this reason, the applied voltage of the piezoelectric element of the ejection unit that has recognized the abnormality is automatically specified, and the applied voltage can be easily changed.

  The liquid ejecting apparatus according to a fourth aspect of the present invention is the liquid ejecting apparatus according to the third aspect, wherein the voltage setting screen includes a graph display unit that displays the applied voltage in a graph for each of the ejecting units. The applied voltage can be changed by expanding and contracting the graph in the graph display section.

  According to the liquid ejecting apparatus, since the applied voltage is displayed in a graph, the operator can intuitively grasp how much the applied voltage should be corrected. Therefore, the applied voltage can be easily corrected.

  A liquid ejecting apparatus according to a fifth aspect of the present invention is the liquid ejecting apparatus according to the fourth aspect, wherein the graph is displayed according to the difference between the maximum value and the minimum value of the applied voltage among the graphs of the voltage graph display unit. The resolution is changed.

  According to this liquid ejecting apparatus, since the resolution is changed according to the difference between the maximum value and the minimum value of each graph, the resolution of the graph display can be optimized.

  A flat panel display manufacturing apparatus according to a sixth aspect of the present invention includes the liquid spraying apparatus according to any one of the first to fifth aspects. A flat panel display according to a seventh aspect of the present invention is manufactured by the flat panel display manufacturing apparatus according to the sixth aspect.

  When ink in which spacer beads are mixed as an ejection head is used as an ejection head, the liquid ejection apparatus can be applied to a manufacturing apparatus for manufacturing a flat panel display. In this case, the liquid is ink mixed with spacer beads dispersedly arranged in the black matrix region. In addition, as the flat panel display, an organic EL display, a plasma display, or the like can be applied.

  An apparatus for manufacturing a solar cell panel according to an eighth aspect of the present invention includes the liquid spraying device according to any one of the first to fifth aspects. A solar cell panel manufacturing apparatus according to claim 9 of the present invention is manufactured by the solar cell panel manufacturing apparatus according to claim 8.

  When used as an ejection head that ejects liquid in which metal particles or the like are mixed as the ejection head, the liquid ejection device can be applied to a manufacturing apparatus that manufactures a solar cell panel. In the solar battery panel, a metal wiring and a metal film for taking out the generated electricity in the panel cell to the outside, a silicon film for converting sunlight into electricity, ITO (transparent conductive film) and the like are formed on a glass substrate. At this time, metal particles in nano units can be mixed in the liquid, and the liquid can be ejected from the ejection head to form a metal film or draw a metal wiring on the glass substrate.

  In the present invention, the flying speed of the liquid is measured, and the applied voltage of the piezoelectric element is individually changed based on the flying speed. As a result, even if the piezoelectric characteristics of the piezoelectric elements vary, by changing the applied voltage individually, the speed of the liquid can be made uniform and the landing timing on the substrate can be made simultaneously. It becomes like this. Therefore, the landing accuracy can be improved, and the yield can be improved.

  Hereinafter, embodiments of the present invention will be described. In the following, a head cleaning apparatus will be described by exemplifying a liquid crystal display manufacturing apparatus which is one of flat panel displays. Accordingly, the ejection head is described as an inkjet head, the liquid is ink, and the particles in the liquid are spacer beads. However, the present invention is not limited to this. For example, when applied to a solar cell panel manufacturing apparatus, particles mixed in a liquid are nano-unit metal particles.

  In FIG. 1, a substrate 1 is a transparent thin plate such as glass. As the substrate 1, a TFT substrate on which a TFT circuit is formed or a color filter substrate on which a color filter is formed can be applied. Here, the substrate 1 will be described as a color filter substrate. The substrate 1 mainly has a pixel region 2 and a black matrix region 3. The pixel area 2 is a pixel area constituting pixels of each color of RGB, and the pixel area 2 is partitioned and formed by a black matrix area 3. In the black matrix region 3, spacers 4 are uniformly distributed in a lattice shape, and when the color filter substrate and the TFT substrate are joined by the spacers 4, a cell gap is formed as a predetermined gap. A liquid crystal panel is formed by sealing liquid crystal in a gap between the two substrates formed by the spacer 4. The spacer 4 may be formed not only on the color filter substrate side but also on the TFT substrate side.

  FIG. 2 shows an outline of the ink spraying device 10. The ink spraying device 10 is installed on a base 11 and mainly includes a transport table 20, linear motor means 21, an X-axis guide 22, a gantry 23, and an ink jet mechanism 24. The ink jet mechanism 24 includes a head block 25, a head slide mechanism 26, a head up / down mechanism 27, a head shift mechanism 28, and a head rotation mechanism 29 and is schematically configured. The head block 25 is equipped with four inkjet heads 30A, 30B, 30C, and 30D (collectively referred to as inkjet heads 30).

  The substrate 1 is mounted on the transfer table 20 and fixedly held by a vacuum suction means or the like. The transport table 20 is driven by the linear motor means 21 and is transported in the X direction (substrate transport direction) in the drawing along the X-axis guide 22 which is a guide rail. The linear motor means 21 includes a stator 21F and a mover 21M. The stator 21F is composed of a superconducting coil, and generates a magnetic field by a current flowing through the coil. The stator 21F is arranged so as to extend linearly in the moving direction of the movable element 21M, that is, in the X direction in the drawing. The mover 21M is a motor with an encoder and is equipped with a superconducting magnet. The mover 21M is propelled and moved along the stator 21F by the magnetic field generated in the stator 21F and the superconducting magnet of the mover 21M. Since the conveyance table 20 is intermittently fed, the operation of the movable element 21M is also intermittently fed.

  The head slide mechanism 26 is attached to a gantry 23 having a gate shape so as to straddle the transport table 20, and moves the entire inkjet mechanism 24 in the Y direction (direction orthogonal to the X direction). The head up-and-down mechanism 27 is a mechanism that raises and lowers the head block 25 in the Z direction (up and down direction approaching and separating from the substrate 1). The head shift mechanism 28 is a mechanism that minutely moves the head block 25 in the X direction, and the head rotation mechanism 29 is a mechanism that rotates the head block 25 at an arbitrary angle.

  The head block 25 has a width (length in the Y direction) that is about half the width of the substrate 1. In recent years, flat panel display manufacturing apparatuses have been used in which a large substrate is divided into a plurality of substrates to be used as a product substrate. Therefore, the substrate 1 has a large size. . Accordingly, when ink is sprayed on the substrate 1 by the head block 25, ink is sprayed on the half area in the Y direction of the substrate 1, and then ink is sprayed on the remaining half area. In FIG. 2, the width of the head block 25 is approximately half that of the substrate 1, but it may be the same length or less than half the length.

  In FIG. 2, a position where the ink spraying device 10 of the base 11 is disposed is an ink spraying area A1, and an area adjacent to the ink spraying area A1 in the Y direction is a maintenance area A2. The maintenance area A2 is an area for performing maintenance such as cleaning of the inkjet head 30 and is provided with a cleaning tank or the like for immersing and cleaning the inkjet head 30 although not illustrated. The maintenance area A2 includes a photographing unit 50 described later. As the head slide mechanism 26 moves the gantry 23 in the Y direction, the inkjet mechanism 24 can reciprocate between the ink spraying area A1 and the maintenance area A2.

  The ink jet mechanism 24 is electrically connected to the control device 32, and the operation of each mechanism provided in the ink jet mechanism 24 is controlled by a command from the control device 32. The control device 32 can perform various operations via a monitor 34, a mouse 35 and a keyboard 36 connected to the computer 33. The monitor 34 constitutes a screen part, and the mouse 35 and the keyboard 36 constitute an input part.

  The configuration of the inkjet head 30 will be described with reference to FIGS. 3 and 4. A large number of nozzles 40 are arranged in a row in the inkjet head 30, and nozzle holes 45 serving as ink ejection ports are arranged at predetermined pitch intervals on the lower surface of the inkjet head 30. From each nozzle 40 of the inkjet head 30, a liquid (spacer ink: simply referred to as ink) in which the spacer 4 shown in FIG. 1 is mixed is ejected, and the ink ejected from each nozzle 40 is ejected. Land on the substrate 1. In the drawing, 16 nozzles 40 are arranged in one inkjet head 30, but actually more nozzles 40, for example, 128 nozzles 40 are arranged in one inkjet head 30. There is something that has been. In FIG. 3, a plurality of nozzles 40 are arranged in one row, but may be arranged in a plurality of rows.

  As shown in FIG. 4, each nozzle 40 includes a chamber 41 for filling ink, and a piezoelectric element 42 is provided on the outer wall of each chamber 41. The piezoelectric element 42 is maintained in a flat state in a non-energized state, but is deformed by applying a voltage. By this deformation operation, pressure is applied to the ink filled in the chamber 41, I try to spray. Each chamber 41 is connected to an ink supply passage 43, and the ink supply passage 43 is connected to an ink tank (not shown) that stores ink. After ink is ejected from the nozzle hole 45, ink is newly filled via the ink supply passage 43.

  When a positive voltage is applied to the piezoelectric element 42, the piezoelectric element 42 is deformed outward as indicated by a two-dot chain line A in FIG. 4, thereby expanding the volume of the chamber 41, and the ink corresponding to the expanded volume is ink. The air is sucked in through the supply passage 43. Thereafter, when a negative voltage is applied to the piezoelectric element 42, the piezoelectric element 42 is deformed inward as indicated by a dashed line B in FIG. As a result, the volume of the chamber 41 is reduced, and pressure is applied to the ink so that the ink is ejected as droplets from the nozzle hole 45.

  Therefore, in order to eject the ink vigorously, a large difference in applied voltage is given. When a large applied voltage is applied, the voltage applied to the piezoelectric element 42 changes greatly instantaneously. For example, when switching from a state in which a positive voltage is applied to the applied voltage 42 to a negative voltage, a large voltage difference is instantaneously applied. When the voltage applied to the piezoelectric element 42 is changed greatly instantaneously (that is, when the amount of change in the voltage of the piezoelectric element 42 at a certain time is increased), the piezoelectric element 42 is rapidly and greatly deformed. As a result, a high pressure acts on the ink inside the chamber 41, and the ink is ejected vigorously from the nozzle 45. On the other hand, when only a small applied voltage is applied, since the deformation amount of the piezoelectric element 42 is small, a very high pressure does not act on the ink inside the chamber 41. For this reason, ink is not ejected so vigorously. That is, the pressure acting on the inside of the chamber 41 changes depending on the applied voltage at the time of ink ejection, and the speed of the ejected ink also changes.

  On the other hand, the piezoelectric element 42 of each nozzle 40 has a structure in which the piezoelectric material is sandwiched between two electrode plates on which the electrode material is formed. The piezoelectric material and the electrode material have individual differences for each piezoelectric element 42. Yes. As the electrode material or the piezoelectric material, for example, an electrode thin film or a piezoelectric film obtained by depositing a deposition material on a substrate by a vacuum deposition method or the like can be applied. Since each piezoelectric element 42 has an individual difference, the electrostatic capacity is different, and each has different piezoelectric characteristics. Therefore, even if the same voltage is applied to each piezoelectric element 42, the pressure applied to the ink filled in the chamber 41 also varies for each nozzle 40. For this reason, since the speed of the ink ejected from the nozzles 40 becomes non-uniform, the landing timing on the substrate 1 varies.

  As described above, by controlling the voltage applied to the piezoelectric element 42, the ink speed can be changed. Therefore, the variation in ink speed caused by the piezoelectric characteristics of the piezoelectric element 42 is eliminated by correcting the voltage applied to the piezoelectric element 42 for each nozzle 40 individually. In the following, the applied voltage that is applied when the piezoelectric element 42 is driven is a negative applied voltage that is deformed inward and a positive applied voltage that is deformed outward. Shall.

  The imaging unit 50 will be described with reference to FIG. The photographing unit 50 is disposed in the maintenance area A2, and includes an LED 52, a half mirror 53, a lens group 54, a reflecting plate 55, a camera 56, an image signal output unit 57, and a receiving container 58. Each part of the imaging unit 50 is configured as an integral unit, and the relative positional relationship with the nozzle 40 can be adjusted.

  The LED 52 serves as a light source for irradiating illumination light. The half mirror 53 is a member that reflects light from the LED 52 and converts the optical path by 90 degrees. The light whose optical path is bent by the half mirror 53 travels to the reflecting plate 55 through the lens group 54. The light reflected by the reflecting plate 55 enters the half mirror 53 again via the lens group 54. The half mirror 53 uses an element having an optical characteristic that reflects light from the LED 52 and transmits light reflected from the reflection plate 55. Thereby, the light reflected by the reflecting plate 55 passes through the half mirror 53 as it is and enters the camera 56. The camera 56 converts incident light into an image signal. An image signal output unit 57 is connected to the camera 56 and outputs an image signal to the voltage setting unit 60. The receiving container 58 is a container that receives ink ejected from the nozzle 40.

  The ink jet mechanism 24 performs the ink spraying process by driving the ink jet head 30 in the ink spraying area A1 during processing. When performing maintenance, the head slide mechanism 26 moves the gantry 23, so that the inkjet mechanism 24 moves from the ink spraying area A1 to the maintenance area A2. In this maintenance area A2, the applied voltage for each nozzle 40 is individually set.

  After the inkjet mechanism 24 moves to the maintenance area A2, the unit of the imaging unit 50 is placed so that each nozzle 40 of the inkjet head 30 is positioned at an upper position between the lens group 54 and the reflection plate 55 of the imaging unit 50. Move and align. This alignment may be performed by moving the inkjet mechanism 24. Due to this alignment, the ink droplet (ink droplet) ejected from the nozzle 40 and flying downward is positioned on the optical path of the optical system of the imaging unit 50, and is thus flying by the camera 56. An image of the ink droplet is taken. Since the direction orthogonal to the paper surface of FIG. 5 is the Y direction, and the nozzles 40 are arranged in a line in the Y direction, the camera 56 acquires images of ink droplets ejected from each nozzle 40. . Then, the camera is photographed so that at least two ink droplets are photographed in the flying direction (Z direction) of the ink droplets (that is, at least two ink droplets ejected from one nozzle 40 are photographed). 56 fields of view are set.

  Next, the voltage setting unit 60 will be described with reference to FIG. The voltage setting unit 60 includes an image signal input unit 61, a speed measurement unit 62, a setting voltage calculation unit 63, a voltage setting unit 64, a voltage driving unit 65, a liquid display screen creation unit 66, a voltage setting screen creation unit 67, and a display screen control. A part 68 is schematically configured. The image signal input unit 61 is an input unit that captures the image signal output from the image signal output 57. The speed measuring unit 62 performs image processing on the captured image signal to generate image data, and calculates a speed given to the ink based on the image data. The set voltage calculation unit 63 calculates an appropriate applied voltage for each nozzle 40 based on the calculated flying speed of the ink. The voltage setting unit 64 holds the applied voltage calculated by the set voltage calculation unit 63 as a set value for each nozzle 40.

  The voltage driving unit 65 performs control to apply the applied voltage set in the voltage setting unit 64 to the piezoelectric element 42 of each nozzle 40. For this reason, the voltage driving unit 65 is connected to all the nozzles 40 (16 nozzles 40A to 40P in FIG. 6), and individually drives the applied voltage to each nozzle 40. ing. The voltage application timing is the same for all nozzles 40. The liquid display screen creation unit 66 creates a screen (a liquid display screen 72 described later) based on the image data generated by the speed measurement unit 62. In addition, the voltage setting screen creation unit 67 creates a screen (voltage setting screen 72 described later) on which an applied voltage can be set for each nozzle 40. The display screen control unit 68 is connected to the liquid display screen creation unit 66 and the voltage setting screen creation unit 67, and performs control to display the created screen on the monitor 34. The display screen control unit 68 is connected to the keyboard 36 and the mouse 35, and performs control to change the display content of the screen in accordance with the operation of the keyboard 36 and the mouse 35.

  The operation of the voltage setting unit 60 will be described. The speed measurement unit 62 performs image processing on the image signal captured by the camera 56 to generate image data as shown in FIG. This image data includes at least ink droplets in flight ejected from each nozzle 40. In the example shown in FIG. 7, the image data is almost the same as the image taken by the camera 56. As an image processing technique, ink droplets are extracted from the image by a technique such as pattern matching or binarization. Two orthogonal axes (YZ coordinate system) are formed in the image data, and each ink droplet is located in the YZ coordinate system. The Y axis of the YZ coordinate system is the Y direction in FIG. 2 and coincides with the arrangement direction of the nozzles 40. The Z axis is the Z direction described above and coincides with the ink flying direction. Since 16 nozzles 40A to 40P are arranged in a row in the inkjet head 30, an image of ejected ink droplets (shown by black circles in the drawing) is only for each nozzle 40 (16 nozzles). ) Is displayed. In the figure, since the number of nozzles 40 is 16, 16 are displayed. However, if there are more nozzles, for example, 128 nozzles 40, 128 nozzles are displayed. The The image data includes four ink droplets in the ink flying direction. In the image data, lines are formed vertically and horizontally (Y direction and Z direction) as indicated by a two-dot chain line. The vertical lines (LA to LP) correspond to the nozzles 40, and the horizontal lines (H1 to H4) correspond to the height.

  If there is no variation in the piezoelectric characteristics of the piezoelectric elements 42 of the nozzles 40, the ink droplets fly toward the substrate 1 at a uniform speed by applying the same voltage to the piezoelectric elements 42 of all the nozzles 40. . At this time, as shown in FIG. 7, all ink droplets are positioned on the intersections of the vertical and horizontal lines. However, as described above, if the piezoelectric characteristics vary, even if the same voltage is applied, the flying speed of the ink droplets becomes non-uniform, and not all the ink droplets are located at the intersection of the vertical and horizontal lines. It becomes like this. The example of FIG. 8 shows an example in which the velocity of the ink droplets ejected from the nozzle 40D and the nozzle 40G is different from other ink droplets.

  The velocity applied to the ink droplet can be calculated based on the distance of the ink droplet. Since ink is ejected intermittently from each nozzle 40 at regular time intervals, the time required for the distance to which the ink droplets have traveled is the aforementioned constant time, and the distance and time can be obtained. The velocity of the droplet can be calculated. In the example of FIG. 8, during time T, the nozzles 40 except for the nozzles 40D and 40G travel a distance L1, the ink droplets of the nozzle 40D travel a distance L2, and the ink droplets of the nozzle 40G travel a distance L3. When the velocity of ink droplets ejected from the nozzles 40 excluding the nozzles 40D and 40G is V1, the velocity of the nozzle 40D is V2, and the velocity of the nozzle 40G is V3, L2 <L1 <L3, so V2 < The relationship V1 <V3 is established. Since the ink droplets ejected from the nozzles 40 excluding the nozzles 40D and 40G are located at the intersections of the vertical and horizontal lines, it is recognized that the speed V1 is an appropriate speed.

  Next, the set voltage calculation unit 63 inputs the speed of each nozzle 40 calculated by the speed measurement unit 62, and sets the applied voltage of the piezoelectric element 42 of each nozzle 40 based on these speeds. When the ink speed is V and the applied voltage of the piezoelectric element 42 is E, the equation “E = (V + α) / β” is established between E and V. Α and β are coefficients based on the capacitance of the piezoelectric element 42 and the like. The applied voltage E at this time is calculated based on the ink velocity V, and may be different from the voltage actually applied to the piezoelectric element 42. Therefore, the applied voltage calculated from the speed V is set as a virtual applied voltage TE. As described above, the speed V1 is an appropriate speed, and the virtual applied voltage calculated from the speed V1 is an appropriate applied voltage, which is set as the reference applied voltage BE (that is, “BE = (V1 + α) / β ").

  On the other hand, the virtual applied voltage TE calculated from the speeds V2 and V3 is different from the reference applied voltage BE. The virtual applied voltage TE2 calculated from the speed V2 is “TE2 = (V2 + α) / β”, and the virtual applied voltage TE3 calculated from the speed V3 is “TE3 = (V3 + α) / β”. Therefore, the difference between the virtual applied voltage TE2 and the reference applied voltage BE is the correction amount (“BE−TE2”), and the difference between the virtual applied voltage TE3 and the reference applied voltage BE is the correction amount (“BE−TE3”). It becomes.

  When the applied voltage currently set for the piezoelectric element 42 of the nozzle 40D is PE2, a voltage obtained by adding a correction amount to the applied voltage PE2 becomes the newly set applied voltage NE2. Then, “NE2 = PE2 + (BE−TE2)”. Similarly, regarding the nozzle 40G, when the applied voltage currently set to the piezoelectric element 42 is PE3 and the newly set applied voltage is NE3, “NE3 = PE3 + (BE−TE3)”. At this time, since BE> TE2, the correction amount of the nozzle 40D becomes a positive value, and a value higher than the currently set applied voltage is set. Further, since BE <TE3, the correction amount of the nozzle 40G is a negative value, and a value lower than the currently set applied voltage is set. On the other hand, for the nozzles 40 other than the nozzles 40D and 40G, since the reference application voltage and the virtual application voltage are the same value, the correction amount is “0”, and the currently set application voltage is not changed.

  Returning to FIG. 6, the optimum setting voltage calculated for each nozzle 40 by the setting voltage calculation unit 63 is output to the voltage setting unit 64. The voltage driving unit 65 drives the piezoelectric element 42 of each nozzle 40 based on the applied voltage set for each nozzle 40 in the voltage setting unit 64. As described above, the nozzle 40D is driven by the applied voltage NE2, the nozzle 40G is driven by the applied voltage NE3, and the other nozzles 40 are driven by the current set voltage PE. Accordingly, the applied voltages of the nozzles 40D and 40G are corrected so that the speed applied to the ink is V1. For this reason, even if the characteristics of the piezoelectric element 42 vary, an optimum applied voltage is set for each nozzle 40 so that the ink speed is uniform. Thereby, there is no variation in the ink speed, and ink can be landed on the substrate 1 at the same time. Since the ink speed is calculated by actually ejecting ink from each nozzle 40 and performing image processing, the state of the nozzle 40 is reflected in real time. As described above, the ink landing accuracy on the substrate 1 can be improved, and the yield can be greatly improved.

  Next, manual change of the applied voltage will be described. As described above, an optimum applied voltage is calculated for each nozzle 40 by the speed measuring unit 62 and the set voltage calculating unit 63, and the voltage driving unit 65 is automatically set to the piezoelectric element 42 by using the calculated applied voltage as a set value. Is driving. Therefore, although the applied voltage is automatically set, the set value of the applied voltage may be inappropriate. For example, as shown in FIG. 9, a noise component is included on the vertical line of the nozzle 40J, and when this is recognized as an ink droplet, the distance L4 between the ink droplet and the noise component is very large. It will be short. Then, the speed V4 based on the distance L4 is calculated as a very low speed, and an applied voltage corresponding to this speed is automatically set, so a very high correction amount of the applied voltage is given to the nozzle 40J. For this reason, the set voltage of the nozzle 40J becomes very high, and this set voltage becomes inappropriate.

  Therefore, after setting the applied voltage automatically, the ink is ejected from each nozzle 40 again to check whether the setting is appropriate. This confirmation operation is performed manually. This is because even if the confirmation work is automatically performed, the noise component may be erroneously recognized again when image processing is performed, and the manual confirmation work is sure.

  FIG. 10 shows two screens, a liquid display screen 71 and a voltage setting screen 72, which are displayed on the monitor 34 when manual setting is performed. The liquid display screen 71 is a screen including almost the same information as the image data subjected to the image processing by the speed measuring unit 62, and is a screen including at least ink droplets. The example of FIG. 10 is a screen displaying ink droplets, vertical and horizontal lines, and nozzles 40 (indicated by AP in the drawing). The liquid display screen 71 is displayed on the monitor 34 from the display screen control unit 68 by the liquid display screen creation unit 66 creating a screen layout based on the image data of the speed measurement unit 62. The voltage setting screen 72 is a screen having two areas: an area where the applied voltage set for each nozzle 40 is displayed as a numerical value (numerical value display area 73) and an area where the applied voltage is displayed as a bar graph (graph display area 74). . The voltage setting screen 72 creates a screen layout based on the applied voltage set for each nozzle 40 in the voltage setting unit 64 and is displayed on the monitor 34 from the display screen control unit 68.

  The ink droplets on the liquid display screen 71 can be selected by operating the mouse 35 (or keyboard 36). By selecting this ink droplet, the nozzle 40 corresponding to the selected ink droplet is specified. In the example of FIG. 10, the vertical lines LA to LP can be selected, and the image of the nozzle 40 on the upper side can also be selected. The nozzle 40 is specified also by selecting these. In addition, the numerical value of each nozzle 40 displayed in the numerical value display area 73 of the voltage setting screen 72 can be edited with the keyboard 36 (or the mouse 35). The bar graph in the graph display area 74 can be edited with the mouse 35 (or the keyboard 36) in a freely stretchable manner. The numerical value display area 73 and the graph display area 74 are interlocked. When any numerical value in the numerical value display area 73 is edited, the corresponding bar graph in the graph display area 74 is automatically expanded and contracted. When any bar graph is expanded or contracted, the corresponding numerical value in the numerical value display area 73 is automatically changed.

  In the liquid display screen 71 displayed on the monitor 34, the operator visually recognizes that the distance between the ink droplets of the nozzle 40J is very short. For example, the ink droplet may be displayed with a clear color so that the operator can easily recognize the ink droplet. When the ink droplet, the vertical line, or the image of the nozzle 40J is selected by operating the mouse 35, the display screen control unit 68 displays the numerical value of the numerical value display area 73 of the voltage setting screen 72 and the numerical value of the nozzle 40J of the graph display area 74. Control the bar graph to be selected. As a result, the nozzle 40J to be manually set is automatically identified. As a method for specifying automatically, it is conceivable that the cursor moves to a numerical value in the numerical value display area 73, or the pointer of the mouse 35 moves to a bar graph. Then, the operator can manually set the applied voltage to an appropriate value by changing the numerical value of the specified numerical value display area 73 or expanding / contracting the bar graph.

  Here, when there are a plurality of application voltages to be manually reset, in order to set another application voltage after setting one application voltage on the voltage setting screen 72, the liquid display screen 71 is used. The target nozzle 40 is selected, and setting is performed again on the voltage setting screen 72. However, the setting is performed on the voltage setting screen 72, and if the target applied voltage can be specified from these, it is not necessary to switch to the liquid display screen 71. In the voltage setting screen 72, the numerical value display area 73 displays the numerical value of the applied voltage in a horizontal row, and therefore it is difficult to specify the target applied voltage from among them. In particular, when a large number (for example, 128) of nozzles 40 are arranged, it is extremely difficult to specify the target applied voltage. On the other hand, when the set voltage is abnormal in the graph display area 74, the target bar graph is protruded extremely or depressed more than the others, so that the target bar graph can be easily obtained. Can be specified. In this respect, since it is excellent in visibility, display by a bar graph is desirable.

  Further, the display range of the bar graph in the graph display area 74 of FIG. 10 is automatically changed by the display screen control unit 68 according to the maximum value and the minimum value of the applied voltage of each piezoelectric element 42. If the difference between the maximum value and the minimum value of the applied voltage is small, the display resolution of the bar graph becomes fine, and it becomes possible to recognize a fine variation amount of the applied voltage to each piezoelectric element 42. On the other hand, if the difference between the maximum value and the minimum value of the applied voltage is large, the display resolution of the bar graph becomes coarse, and it is possible to easily grasp the nozzle in which the set value of the applied voltage protrudes from the other nozzles 40. become.

  In the above embodiment, the ink velocity is calculated by ejecting ink downward from the nozzle 40, acquiring an image of the flying ink droplet, and performing image processing. The speed of ink may be obtained by a method. For example, each nozzle 40 is arranged on the top of a sheet that moves in the horizontal direction at a constant speed, and ink is ejected from each nozzle 40 toward the moving sheet. The trajectory of ink landed on the sheet is measured by performing image processing, for example. Since the distance between each nozzle 40 and the sheet is constant, and the moving speed of the sheet is also constant, the ink speed can be obtained by measuring the trajectory of the ink that has landed on the sheet.

It is structure explanatory drawing of the board | substrate with which a spacer is spread | dispersed. It is an external view which shows the whole structure of an ink dispersion | distribution stage. It is a structure explanatory view showing the tip part of an ink jet head. It is sectional drawing of the nozzle which comprises an inkjet head. It is a block diagram which shows the structure of a speed measurement part. It is a block diagram which shows the structure of a voltage setting part. It is a figure which shows an example of the image data containing an ink. It is a figure which shows the other example of the image data containing ink. It is a figure which shows the other example of the image data containing ink. It is a figure which shows an example of a liquid display screen and a voltage setting screen.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 10 Ink spreader 35 Mouse 36 Keyboard 41 Chamber 42 Piezoelectric element 50 Image pick-up part 56 Camera 60 Voltage setting part 62 Speed measurement part 63 Setting voltage calculation part 64 Voltage setting part 65 Voltage drive part 66 Liquid display screen creation part 67 Voltage setting Screen creation unit 68 Display screen control unit 71 Liquid display screen 72 Voltage setting screen 73 Numerical display area 74 Graph display area

Claims (9)

A liquid ejecting apparatus that ejects the liquid from an ejection head provided with an array of ejection units that eject liquid containing fine particles toward the substrate while the substrate is being transported,
The ejection unit includes a chamber for filling a liquid having a liquid ejection port at a tip thereof, and a piezoelectric element provided in the chamber. By applying a voltage to the piezoelectric element, the volume of the chamber is increased. It is changed so that the liquid is ejected from the ejection port,
A speed measuring unit that individually measures the flying speed of the liquid ejected from each ejection unit for each liquid;
Based on the measured flying speed for each liquid, a voltage setting unit that performs control to individually change the voltage applied to the piezoelectric element for each ejection unit;
A liquid ejecting apparatus comprising: A photographing unit for photographing an image in which at least two liquids in flight ejected from one ejection unit are included;
The liquid ejecting apparatus according to claim 1, wherein the velocity measuring unit calculates the velocity of the liquid based on a distance between two liquids included in an image photographed by the photographing unit. A screen for displaying a liquid display screen for displaying a liquid included in the image, a voltage setting screen for displaying a voltage applied to the piezoelectric element for each ejection unit, and contents displayed on the screen An input unit for operation,
The liquid display screen allows one liquid to be selected from among the liquids by operating the input unit, and the voltage setting screen changes the applied voltage for each ejection unit by operating the input unit. Is possible,
When one liquid is selected from the liquids displayed on the liquid display screen, an applied voltage of the ejection unit corresponding to the selected liquid is selected from the ejection units displayed on the voltage setting screen. The liquid ejecting apparatus according to claim 2.   The voltage setting screen includes a graph display unit that displays the applied voltage in a graph for each of the injection units, and the applied voltage can be changed by expanding and contracting the graph of the graph display unit. The liquid ejecting apparatus according to claim 3, wherein   The liquid ejecting apparatus according to claim 4, wherein the resolution of the graph display is changed in accordance with a difference between the maximum value and the minimum value of the applied voltage among the graphs of the voltage graph display unit.   An apparatus for manufacturing a flat panel display, comprising the liquid ejecting apparatus according to claim 1.   A flat panel display manufactured by the flat panel display manufacturing apparatus according to claim 6.   An apparatus for manufacturing a solar cell panel, comprising the liquid ejecting apparatus according to claim 1.   The solar cell panel manufactured with the manufacturing apparatus of the solar cell panel of Claim 8.

Images