JP2014113691A - Discharge rate evaluation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge rate evaluation method capable of highly accurately evaluating a discharge rate from impacted dots discharged from liquid droplet discharge heads.SOLUTION: The discharge rate evaluation method includes: a discharge step of discharging a test pattern 70 in which measurement dots 81 are arranged in a matrix; and an evaluation step of measuring an area of the measurement dots 81, and evaluating a discharge rate of liquid. The evaluation step includes a process for evaluating impacted positions of the measurement dots 81, and a process for correcting a measurement value of the area of the impacted dots if a difference between a distance between one of the measurement dots 81 as an evaluation target and the measurement dot 81 adjacent to the evaluation target and a distance between corresponding discharge nozzles exceeds a predetermined threshold. Depending on a magnitude of the distance between the measurement dot 81 as the evaluation target and the measurement dots 81 adjacent to both sides of the evaluation target relative to the distance between the corresponding discharge heads, it is determined on which of the adjacent measurement dots 81 the correction process is performed.

Description

  The present invention relates to a discharge amount evaluation method in a droplet discharge device.

An ink jet recording head used in an image recording apparatus (liquid ejecting apparatus) such as a printer has been put to practical use as a liquid droplet ejecting head having an ejection nozzle capable of ejecting liquid in the form of liquid droplets. Recently, application to various apparatuses has been considered by taking advantage of the feature that a very small amount of liquid can be discharged with high accuracy. For example, color material discharge heads used for manufacturing color filters such as liquid crystal displays, electrode material discharge heads used for electrode formation such as organic EL (Electro Luminescence) displays, FEDs (surface emitting displays), and the like have been proposed.
This type of droplet discharge head generally includes a plurality of nozzle openings arranged at equal intervals, and is configured to discharge droplets from individual nozzle openings. For this reason, the liquid is exposed to the atmosphere at the nozzle opening, and the solvent component of the liquid evaporates through the meniscus (the free surface of the liquid exposed at the nozzle opening). The evaporation of the solvent component causes an increase in the concentration of other components constituting the liquid, causing a flying curve of the droplet or clogging of the nozzle opening. If the nozzle opening becomes clogged, droplets are not ejected from the nozzle opening, which may cause various problems. For example, in a recording head, a dot is not landed at an appropriate landing position on a recording medium, which causes a deterioration in image quality, or a liquid discharge amount deviates from an original amount. There is a possibility that characteristics cannot be obtained.

Although it is important to detect the presence or absence of missing dots in order to obtain a desired performance, this detection has been performed using a visually visible test pattern. For example, in the above-described image recording apparatus, a test pattern is recorded on recording paper, and the density of the test pattern is optically read (for example, Patent Document 1).
In addition, as one of the evaluation methods of the discharge amount of the droplet discharge head, the area of each landing dot of the test pattern formed by discharging the liquid from the liquid discharge device is calculated, and the corresponding discharge nozzle of the droplet discharge head There is known a method for evaluating whether or not a difference from a predetermined discharge area (design value) is within an allowable range with respect to a threshold value.

JP 2000-43382 A

Recently, in addition to color inks such as cyan, magenta, yellow, and black, it has also been considered to adjust the image quality by ejecting a colorless and transparent liquid called clear ink from the droplet ejection head as ink. . For example, transparent ink is used to make the gloss of an image uniform. Specifically, when recording on plain paper (paper that has not been glossed) with pigmented colored ink, there is a difference in gloss between the portion recorded with colored ink and the ground color portion of plain paper. May occur. In this case, when the pigment ink is landed on the non-recording area, the gloss of the recording area and the non-recording area can be made uniform.
In addition, as the ink to be used, there may be used only one in which a solid content is dissolved in a solvent or only a solvent having no solid content.
However, since the above-described transparent liquid is difficult to visually recognize even when a test pattern is recorded, it is difficult to optically read or electrically recognize and recognize the test pattern. In addition, the system becomes complicated and expensive, and it is difficult to accurately detect the landing area of the test pattern.
Also, when ink with very little solid content or no solid content is used, the penetrating dot shape tends to vary due to its high permeability to the ink absorbing layer of the recording medium, and the outline of the landing dot However, there is a problem that accurate area measurement may not be possible because the image is visually blurred or recognized indefinitely.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  [Application Example 1] The discharge amount evaluation method according to this application example is a liquid droplet discharge apparatus including a liquid droplet discharge head having a plurality of discharge nozzles arranged at a predetermined interval, and the liquid is applied to a recording medium having an ink absorption layer. A discharge step of discharging a liquid from a droplet discharge head to form a test pattern in which the landing dots of the liquid corresponding to the discharge nozzles are arranged in a matrix; and the landing dots in which the liquid spreads over the ink absorption layer An evaluation step of evaluating the liquid discharge amount for each of the landing dots corresponding to the discharge nozzle based on the evaluation result, the evaluation step comprising: And a process of evaluating the landing position of the landing dot, and in the process of evaluating the landing position, the landing dot to be evaluated and the landing dot to be evaluated are adjacent to the landing dot. When there is a difference exceeding a predetermined threshold value between the physical quantity with the landing dot and the corresponding physical quantity between the discharge nozzles, the physical quantity measurement value of the landing dot having a difference exceeding the threshold value is set to a predetermined value. It includes a process of correcting by applying a correction coefficient.

According to this application example, a test pattern in which liquid landing dots are arranged in a matrix is formed on the ink absorption layer of the recording medium, and the area of the landing dots of the test pattern is evaluated. Even when a highly transparent liquid is used, the contrast of the outer periphery of each landing dot in the plan view is uniform and easy to recognize, and if the landing position of the landing dot is shifted, the landing position shift is reduced. It becomes easy to recognize. In addition, because the landing dots of the test pattern are arranged at substantially equal intervals, for example, the landing dots of a stable shape are formed by the liquid permeation between adjacent landing dots, so that, for example, The accuracy of area evaluation can be improved even when a liquid having a very low solid content or a highly permeable liquid containing no solid content is used.
Further, in this application example, there is a difference exceeding a predetermined threshold value between the physical amount of the landing dot to be evaluated and the landing dot adjacent to the landing dot to be evaluated and the physical amount between the corresponding discharge nozzles. In such a case, the inventor has found that it is effective to apply a predetermined correction coefficient to the physical quantity measurement value of the landing dot that has a difference exceeding the threshold value.
Therefore, according to this application example, even when a transparent liquid having a high light transmittance or a liquid having a low solid content and a high permeability is used, the discharge amount evaluation capable of accurately evaluating the area of the landing dot A method can be provided.

  Application Example 2 In the ejection amount evaluation method described in the application example, the physical quantity is an interval.

  In the above application example, when the landing positions of the landing dots are shifted and the interval between adjacent landing dots is far away from or close to the interval between the corresponding discharge nozzles, the physical amount of the landing dot is predetermined. Between the physical quantity of the landing dot to be evaluated and the landing dot adjacent to the landing dot to be evaluated, and the physical quantity between the corresponding discharge nozzles. The inventor has found that when there is a difference exceeding a predetermined threshold, it is effective to multiply the physical quantity measurement value of the landing dot that has the difference exceeding the threshold by a predetermined correction coefficient for correction.

  Application Example 3 In the ejection amount evaluation method described in the application example, the physical quantity is an area.

  In this application example, the landing dot area when the landing position of the landing dot is shifted and the interval between adjacent landing dots is far apart or close to the interval between the corresponding discharge nozzles is predetermined. Therefore, a process for correcting the area is required. Here, when there is a difference exceeding a predetermined threshold value between the physical amount of the landing dot to be evaluated and the landing dot adjacent to the landing dot to be evaluated and the physical amount between the corresponding discharge nozzles The inventor has found that it is effective to apply a predetermined correction coefficient to the area measurement value of the landing dot that has a difference exceeding the threshold value.

  Application Example 4 In the discharge amount evaluation method according to the application example described above, the interval or area between the landing dot to be evaluated and the landing dot adjacent to both sides thereof is the interval between the corresponding discharge nozzles. If both are large, the correction processing is performed only for the landing dots that are more apart from each other in distance or area.

  The inventor has found that the area of the landing dot can be accurately evaluated by this application example.

  Application Example 5 In the discharge amount evaluation method according to the application example described above, the interval or area between the landing dot to be evaluated and the landing dot adjacent on both sides thereof is the interval between the corresponding discharge nozzles. On the other hand, when one is separated and the other is close, the correction process is performed only for a landing dot having a larger absolute amount than the threshold.

  The inventor has found that the area of the landing dot can be accurately evaluated by this application example.

  Application Example 6 In the discharge amount evaluation method according to the application example described above, the interval or area between the landing dot to be evaluated and the landing dot adjacent to both sides thereof is the interval between the corresponding discharge nozzles. On the other hand, when one is large and the other is small, the correction processing is performed on the landing dot having the larger absolute amount with respect to the threshold value.

  The inventor has found that the area of the landing dot can be accurately evaluated by this application example.

According to this application example, a test pattern in which liquid landing dots are arranged in a matrix is formed on the ink absorption layer of the recording medium, and the area of the landing dots of the test pattern is evaluated. Even when a highly transparent liquid is used, the contrast of the outer periphery of each landing dot in the plan view is uniform and easy to recognize, and if the landing position of the landing dot is shifted, the landing position shift is reduced. It becomes easy to recognize. In addition, because the landing dots of the test pattern are arranged at substantially equal intervals, for example, the landing dots of a stable shape are formed by the liquid permeation between adjacent landing dots, so that, for example, The accuracy of area evaluation can be improved even when a liquid having a very low solid content or a highly permeable liquid containing no solid content is used.
In addition, in this application example, the landing dot area when the landing position of the landing dots is shifted and the interval between adjacent landing dots is far apart or close to the interval between the corresponding discharge nozzles is as follows. Since it becomes larger than the case where they are arranged at a predetermined interval, a process for correcting the area is required. Here, when the distance between the landing dot to be evaluated and the landing dot adjacent to both sides thereof is larger than the distance between the corresponding discharge nozzles, the landing dot having a larger distance is used. If both are smaller than the interval between the corresponding discharge nozzles, the correction process is performed for the landing dot with the smaller interval, and the corresponding discharge nozzles The inventors have found that it is effective to perform a correction process on the landing dots having a smaller distance when one is far apart and the other is smaller than the distance.
Therefore, according to this application example, even when a transparent liquid having a high light transmittance or a liquid having a low solid content and a high permeability is used, the discharge amount evaluation capable of accurately evaluating the area of the landing dot A method can be provided.

  Application Example 7 In the discharge amount evaluation method according to the application example described above, the interval or area between the landing dot to be evaluated and the landing dot adjacent to both sides thereof is the interval between the corresponding discharge nozzles. On the other hand, when one is large and the other is small, the correction is performed on the landing dot having the larger absolute amount with respect to the threshold value.

  According to this application example, the inventor has found that the area of the landing dot can be accurately evaluated.

  Application Example 8 In the ejection amount evaluation method according to the application example described above, in the evaluation step, the physical quantity and the analysis are performed by performing an imaging process for capturing an image of the landing dot and an analysis process for analyzing the image. It is preferable to evaluate the landing position.

  According to this application example, since the area of the landing dot is evaluated based on the captured image, the area is evaluated with high accuracy and efficiency even for a small landing dot compared to the case where the area is visually evaluated. be able to.

  Application Example 9 In the ejection amount evaluation method described in the application example, the liquid is a transparent liquid having high light transmittance.

  According to this application example, even when using transparent ink, which is difficult to visually recognize or image with a conventional ejection amount evaluation method that optically recognizes a test pattern formed of a liquid that is easy to visually recognize, such as color ink. The test pattern can be visually recognized or imaged, and the landing area of the liquid can be detected with high accuracy, thereby contributing to the stabilization of the liquid ejection characteristics of the nozzle.

The perspective view which shows schematic structure of a droplet discharge apparatus. The top view which looked at schematic structure of the droplet discharge head from the nozzle surface, and the blowing part are front sectional views schematically showing the discharge mechanism of the nozzle of the droplet discharge head. FIG. 3 is a partial front sectional view for explaining an example of a recording medium used in the ejection amount evaluation method of the present embodiment. FIG. 3 is a partial front sectional view for explaining an example of a recording medium used in the ejection amount evaluation method of the present embodiment. The functional block diagram when a droplet discharge apparatus functions as a discharge amount evaluation apparatus. 6 is a flowchart illustrating a discharge amount evaluation method according to the present embodiment. FIG. 3 schematically shows a test pattern formed on a recording medium in a discharge amount evaluation method, where (a) is a plan view showing the entire test pattern, and (b) is a positional relationship between measurement dots and dummy dots. The partial top view which expands and shows.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following drawings, the scale of each layer and each member is shown different from the actual scale so that each layer and each member can be recognized.

(Droplet discharge device)
First, a droplet discharge device IJ that forms a recorded matter (printed matter) by discharging a liquid onto a recording medium will be described with reference to FIG. There are various types of droplet discharge devices, but a device using an ink jet method is preferable. The ink jet method is suitable for microfabrication because it can discharge minute droplets.

FIG. 1 is a perspective view showing a schematic configuration of a droplet discharge device IJ according to the present embodiment.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, the XYZ rectangular coordinate system shown in FIG. 1 is set, and each member will be described with reference to this XYZ rectangular coordinate system. The XYZ orthogonal coordinate system is set so that the X axis and the Y axis are parallel to the work stage 102, and the Z axis is set in a direction orthogonal to the work stage 102. 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.

  In FIG. 1, a droplet discharge device IJ is a device that forms a desired recording (printing) pattern by discharging a functional liquid as droplets onto a recording medium by, for example, an inkjet method. It is also what performs quantity evaluation methods.

  The droplet discharge device IJ includes an apparatus base 101, a work stage 102, a stage moving device 103, a carriage 104, a droplet discharge head 20, a carriage moving device 106, a tube 107, a first tank 108, a second tank 109, and a third tank. 110 and a control device 10.

  The apparatus base 101 is a support base for the work stage 102 and the stage moving apparatus 103. The work stage 102 is installed on the apparatus base 101 so as to be movable in the X-axis direction by a stage moving device 103, and a recording medium P conveyed from an upstream conveying device (not shown) is transferred by a vacuum suction mechanism. Hold on the XY plane. The stage moving device 103 includes a bearing mechanism such as a ball screw or a linear guide, and moves the work stage 102 in the X-axis direction based on a stage position control signal indicating the X coordinate of the work stage 102 input from the control device 10. Let

The carriage 104 holds the droplet discharge head 20 and is provided so as to be movable in the Y-axis direction and the Z-axis direction by the carriage moving device 106. The droplet discharge head 20 includes a plurality of nozzles (not shown), and discharges liquid having a predetermined functionality as droplets based on drawing data and drive control signals input from the control device 10. The droplet discharge head 20 is connected to a tube 107 via a carriage 104.
A configuration example in which a color filter material as a liquid is ejected as droplets from the droplet ejection head 20 in order to produce a color filter substrate by the droplet ejection device IJ will be described. That is, the droplet discharge head 20 is supplied with the color filter material for R (red) from the first tank 108 via the tube 107 to the nozzle corresponding to R (red), and the nozzle corresponding to G (green). The color filter material for G (green) is supplied from the second tank 109 via the tube 107, and the color filter for B (blue) is supplied from the third tank 110 to the nozzle corresponding to B (blue) via the tube 107. Material is supplied.

  Here, the nozzles formed in the droplet discharge head 20 in the present embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram showing the arrangement of the nozzles drilled in the droplet discharge head 20, and shows a state seen from the lower side of the carriage 104 in FIG. Here, the vertical direction of the drawing is shown as the Y-axis direction.

  In the present embodiment, as illustrated, the droplet discharge head 20 includes nozzle blocks 20R, 20G, and 20B that discharge color filter materials corresponding to R, G, and B. Specifically, the color filter material for R is supplied from the first tank 108 through the tube 107 to the nozzle block 20R. The nozzle block 20G is supplied with a G color filter material from the second tank 109 via the tube 107. Further, the color filter material for B is supplied from the third tank 110 to the nozzle block 20B through the tube 107. In each of the nozzle blocks 20R, 20G, and 20B, 12 discharge nozzles 21 to 32 are arranged in a substantially straight line, and the arrangement direction thereof coincides with the X-axis direction.

  As described above, a discharge mechanism is formed for each nozzle in each of the perforated nozzles in the droplet discharge head 20, and pressure is generated on each color liquid in the droplet discharge head 20 to generate a predetermined amount. Each color liquid is ejected from the nozzle. Of course, the discharge mechanism has the same structure for all nozzles.

  In the present embodiment, the discharge mechanism has the structure shown in the blow-out portion of FIG. 2, and uses the piezoelectric element 2 as a drive element as a drive body (actuator). That is, when a voltage waveform is applied between the electrodes 2c at both ends of the piezoelectric element 2 and the ground line (GND), the piezoelectric element 2 contracts or expands due to electrostriction and deflects the diaphragm 3 in the direction of the arrow. Each color liquid present in the pressurizing chamber 4 formed in the middle of the liquid flow path is pressurized. As a result, the pressurized color liquids are discharged as droplets L from the discharge nozzles 32 (21 to 31) formed in the bottom surface member 8 of the droplet discharge head 20. The discharge mechanism may be, for example, a so-called thermal method using a heating element as a driver.

  By the way, in this embodiment, in order to simplify the description, it is assumed that 12 nozzles are formed in each nozzle block. Actually, however, tens to hundreds of nozzles are formed at a predetermined pitch. ing. In addition, each nozzle block may have a plurality of nozzle rows such as two rows. For example, in the case of two rows, the nozzle drilling positions are in a staggered arrangement in which the nozzle rows are shifted from each other by a half pitch. In some cases.

  Returning again to FIG. 1, the carriage moving device 106 has a bridge structure straddling the device base 101, and includes a bearing mechanism such as a ball screw or a linear guide in the Y-axis direction and the Z-axis direction, and is input from the control device 10. Based on the carriage position control signal indicating the Y and Z coordinates of the carriage 104, the carriage 104 is moved in the Y-axis direction and the Z-axis direction.

  The control device (control unit) 10 outputs a stage position control signal to the stage moving device 103, outputs a carriage position control signal to the carriage moving device 106, and outputs drawing data and a drive control signal to the droplet discharge head 20. By performing synchronous control of the droplet discharge operation by the droplet discharge head 20, the positioning operation of the recording medium P by the movement of the work stage 102, and the positioning operation of the droplet discharge head 20 by the movement of the carriage 104, the recording medium A droplet of a color filter material (liquid) is ejected to a predetermined position on P.

  By the way, in general, the droplet discharge head 20 has a variation in the discharge amount of the droplet L between the discharge nozzles. The reason for this is, for example, the structure of the flow path inside the head. Therefore, the droplet discharge device IJ according to the present embodiment performs nozzle inspection for detecting the discharge state of the droplet L at each discharge nozzle of the droplet discharge head 20 prior to the discharge operation to the recording medium P by the droplet discharge head 20. The variation between the discharge nozzles is adjusted based on the nozzle inspection result.

  In addition, the droplet discharge head 20 may affect the discharge amount of each nozzle by discharging droplets from both adjacent nozzles. Therefore, the ejection characteristics of the nozzles are acquired in a state where the influence on the ejection characteristics between the nozzles is prevented by performing ejection based on a plurality of ejection patterns. In addition, in the droplet discharge head 20 according to the present embodiment, when the amount of the droplet L based on one discharge operation is very small, a plurality of droplets discharged from each nozzle make one dot (liquid (Reservoir) may be configured. As a result, a sufficiently large dot can be formed, and it is possible to accurately correct the variation in the discharge amount between the nozzles based on the area of each dot as will be described later.

  The droplet discharge device IJ includes a discharge amount evaluation unit 50 that evaluates the discharge amount of the droplet L from each nozzle of the droplet discharge head 20. Next, the configuration of the discharge amount evaluation unit 50 will be described with reference to the drawings.

(Discharge inspection section)
FIG. 3 is a schematic diagram showing the configuration of the ejection amount evaluation unit 50 of the droplet ejection apparatus IJ.
As shown in FIG. 3, in this embodiment, the discharge amount of the discharge nozzle of the liquid discharge head (20) is evaluated using the test recording medium P and the discharge amount evaluation unit 50. The ejection amount evaluation unit 50 can be attached to, for example, the carriage 104 in the droplet ejection apparatus IJ shown in FIG.
The discharge amount evaluation unit 50 includes an imaging unit 171, an optical system 172, an illumination unit 173, a discharge amount evaluation unit control circuit 174, and a storage unit 175. A part of the illumination light emitted from the illumination unit 173 is reflected by the surface of a test pattern (described later) formed on the recording medium P, and enters the imaging unit 171 through the optical system 172. .

  For example, a CCD (Charge Coupled Device) camera is used as the imaging unit 171 and includes a light receiving element that converts received light into electric charge, a charge coupled element that reads out the electric charge, and the like. The optical system 172 includes a single lens group or a plurality of lens groups. An image picked up by the image pickup unit 171 is enlarged by, for example, about 6 to 10 times the image pickup object by the optical system 172. The illumination unit 173 is configured by ring illumination that annularly surrounds the optical axis between the imaging target and the imaging unit 171.

  The ejection amount evaluation circuit 14 controls on / off of the imaging unit 171 and controls the focal length and the diaphragm of the optical system 172. Further, the ejection amount evaluation circuit 14 also has a function of analyzing the imaging result of the imaging unit 171. More specifically, the ejection amount evaluation circuit 14 receives the electric charge read by the charge coupled device of the imaging unit 171 as an electric signal, and stores the electric signal in the storage unit 175 as image data. Further, the ejection amount evaluation circuit 14 reads and analyzes the image data stored in the storage unit 175, and stores the analysis result in the storage unit 175.

Next, the recording medium P used in the ejection amount evaluation method of this embodiment will be described in detail with reference to the drawings. 4A and 4B schematically illustrate an example of the recording medium P used in the present embodiment. FIG. 4A is a partial front sectional view, and FIG. 4B is an enlarged view of FIG. It is a fragmentary sectional view explaining typically.
In FIG. 4, the recording medium P has a base material 42 and an ink absorption layer 43 laminated on the base material 42.

  In the ink absorbing layer 43, a large number of void cells 45 are formed by dispersing particles such as silica and alumina in a transparent bonding agent (binder) 44 such as PVA. The surface of the bonding agent 44 of the ink absorption layer 43 is extremely smooth, but a large number of void cells 45 on the order of several μm or smaller are formed by dispersed silica or alumina particles. Of water. The ink absorption layer 43 has a substantially uniform thickness, and the thickness of the ink absorption layer 43 is appropriately set according to the liquid discharge amount. For example, the smaller the ejection amount is, the higher the evaluation accuracy of the ejection amount evaluation can be by reducing the thickness of the ink absorption layer 43. For example, if the discharge amount is about several picoliters, the thickness of the ink absorption layer 43 may be about 10 μm.

  The base material 42 is made of a material that does not absorb the absorption component absorbed by the ink absorption layer 43 of the discharged liquid. For example, PET (Polyethylene terephthalate) or the like can be used for the base material 42.

  Next, a method for evaluating the discharge amount of the discharge nozzle of the droplet discharge head 20 performed by the droplet discharge apparatus IJ according to the present embodiment will be described with reference to the drawings. FIG. 5 is a functional block diagram when the droplet discharge device IJ functions as a discharge amount evaluation device.

  As shown in FIG. 5, the control device 10 includes a CPU 11 and a memory 12, a drive control signal generation circuit 13, and a discharge amount evaluation circuit 14 that are connected to each other via a bus line.

  Although not shown, the control device 10 includes a control circuit that controls the movement of the stage moving device 103 and a control circuit that controls the movement of the carriage moving device 106. When the CPU 11 ejects droplets onto the recording medium P, the CPU 11 performs calculations relating to the ejection start position, main scanning, and sub scanning, and drives the linear motor for driving the stage moving device 103 and the carriage moving device 106 via the control circuit. Each drive linear motor is configured to output a predetermined control signal and move. As a result, the nozzle and the recording medium P are moved relative to each other to function as a droplet discharge device IJ that draws a predetermined pattern or image on the recording medium P.

  In the control device 10, the CPU 11 performs the nozzle classification calculation and the discharge control calculation according to the discharge characteristic acquisition processing program stored in the memory 12. Based on the calculated ejection control data, the drive control signal generation circuit 13 is controlled to generate a predetermined drive control signal and output it to the droplet ejection head 20. In the droplet discharge head 20, a drive signal generated according to the output drive control signal is applied to the piezoelectric element 2 of each discharge nozzle, and each liquid having a predetermined functionality supplied from the liquid supply device 15 is discharged. It discharges toward the ink absorption layer (43) of a recording medium (P) from a nozzle.

  For the liquid that has been ejected and landed on the recording medium (P), the ejection amount ejected from each nozzle is grasped by a later-described ejection amount evaluation method using the ejection amount evaluation unit 50, and the data representing the ejection amount is the ejection amount. It is output to the evaluation circuit 14. The CPU 11 controls the discharge amount evaluation circuit 14 to measure the actual discharge amount for each nozzle from the data representing the discharge amount. Then, a discharge characteristic acquisition calculation is performed using the drive signal generated according to the output drive control signal and the actual discharge amount, and the calculation data is stored in the memory 12 to acquire the discharge characteristic for each nozzle. To do.

  Next, specific processing of the discharge amount evaluation method performed by the discharge amount evaluation unit 50 will be described. The procedure is defined in the processing program (see FIG. 5) stored in the memory 12, and the CPU 11 reads this processing program and executes the processing using the memory 12 as a working memory as appropriate.

FIG. 6 is a flowchart showing the discharge amount evaluation method of the present embodiment. FIG. 7 schematically shows a test pattern formed on the recording medium P in the ejection amount evaluation method of the present embodiment. FIG. 7A is a plan view showing the entire test pattern, and FIG. It is a fragmentary top view which expands and shows the positional relationship of the dot for a measurement and a dummy dot.
In the ejection amount evaluation method of this embodiment, the droplet ejection device IJ first moves the carriage 104 by the carriage moving device 106 as shown in step S1 of FIG. And face each other.

Next, in order to evaluate the discharge amount of the droplet discharge head 20, a test pattern 70 is formed by discharging liquid from the droplet discharge head 20 onto the ink absorption layer 43 of the recording medium P in step S <b> 2. As the liquid, for example, a transparent ink having a high light transmittance can be used.
As shown in FIG. 7, the test pattern 70 in the ejection amount evaluation of this embodiment is a pattern in which a plurality of landing dots (dummy dots 71 and measurement dots 81) are arranged in a matrix in the vertical and horizontal directions at substantially equal intervals. In this test pattern 70, the interval between the adjacent landing dots (dummy dots 71 and measurement dots 81) is adjacent to the discharge nozzles 21 to 32 of the nozzle blocks 20R, 20G, and 20B of the droplet discharge head 20 shown in FIG. This corresponds to the interval between nozzles.
In addition, the landing dots of the test pattern 70 are formed in a plurality of vertical and horizontal directions at substantially equal intervals, and the measurement dots 81 to be evaluated by the ejection amount evaluation method of the present embodiment and substantially equal intervals so as to surround the periphery thereof. And dummy dots 71 formed in a plurality of rows and columns. In FIG. 7, the measurement dots 81 are indicated by black circles and the dummy dots 71 are indicated by white circles. However, this is for convenience in making it easy to distinguish between the measurement dots 81 and the dummy dots 71. It does not limit the color of the landing dots.
A plurality of dummy dots 71 are formed on the extension line in the alignment direction of the measurement dots 81 formed at equal intervals in the horizontal direction on the paper surface with an interval D3 from the adjacent measurement dots 81, on the paper surface. A plurality of adjacent measurement dots 81 are formed at intervals D4 on the extension line of the measurement dots 81 arranged at equal intervals in the vertical direction at intervals D2. Here, the distances D1 and D2 between the measurement dots 81 adjacent to the measurement dots 81 formed at equal intervals in the vertical and horizontal directions and the distances D3 and D4 between the measurement dots 81 and the dummy dots 71 adjacent to each other are as follows: The relationship of D1 = D3 and D2 = D4 is established. The vertical and horizontal intervals D1 and D2 between the measurement dots 81 have a relationship of D1 ≧ D2, for example.
In FIG. 7, an example is shown in which three measuring dots 81 are arranged at equal intervals, which are landed at equal intervals, but this is the minimum configuration of the present invention on a limited paper surface. It should be noted that this is for convenience of explanation and is not consistent with the number of nozzles of the droplet discharge head 20 shown in FIG.

As described above, by forming the measurement dots 81 arranged in a matrix at substantially equal intervals as the test pattern 70 formed on the ink absorbing layer 43 of the recording medium P, the landing of the measurement dots 81 is achieved. Accurate evaluation can be performed in the later-described discharge amount evaluation performed by evaluating the area. That is, the regular matrix pattern arrangement makes the contrast of the outer periphery of each measurement dot 81 uniform in a plan view even when a transparent liquid with high light transmittance is used. It becomes easy to recognize, and when the landing position of the measurement dot 81 is shifted, it is easy to recognize the landing position shift.
Further, when the test pattern 70 is formed, the measurement dots 81 having a stable shape are formed by balancing the penetration of the liquids of the adjacent measurement dots 81 into the ink absorption layer 43. For example, the solid content is very small. Alternatively, even when a highly permeable liquid that does not contain a solid content is used, the accuracy of area evaluation can be improved.
In addition, by providing the dummy dots 71 arranged in a plurality of vertical and horizontal directions at substantially equal intervals so as to surround the circumference of the measurement dots 81, the shape of the measurement dots 81 arranged in the outermost outline of the measurement dot 81 formation region However, since it is stably formed in the same manner as the measurement dots 81 formed on the inner side, it is possible to perform highly accurate ejection amount evaluation with any measurement dot 81.

Next, the test pattern 70 is analyzed to evaluate the discharge amount.
In the discharge amount evaluation, first, as shown in step S3, a landing area measurement of a predetermined measurement dot 81 as a landing dot to be a discharge amount evaluation target of the test pattern 70 is performed. This landing area measurement includes a process of evaluating the landing position of the measurement dot 81 to be measured. Specifically, light is emitted from the illumination unit 173 of the ejection amount evaluation unit 50 to the test pattern 70 formation region of the recording medium P, and the optical system 172 is controlled by the ejection amount evaluation unit control circuit 174 to adjust the focus and the like. Then, the measurement dot 81 to be evaluated is imaged by the imaging unit 171. The imaging range by the imaging unit 171 at this time may be a range including only one measurement dot 81 or may be a range including a plurality of measurement dots 81.
The electrical signal of the imaged measurement dot 81 is stored in the storage unit 175 as image data.

  In the discharge amount evaluation, next, in step S4, the discharge amount evaluation circuit 14 reads and analyzes the image data stored in the storage unit 175, and calculates a correction value for correcting the landing area measurement value as necessary. calculate. More specifically, in the read image data, the interval between the measurement dot 81 to be evaluated and the measurement dot 81 adjacent to the measurement dot 81 to be evaluated, and the corresponding ejection of the droplet ejection head 20 When there is a difference exceeding a predetermined threshold between the nozzles (the discharge nozzles of any of the discharge nozzles 21 to 32 in FIG. 2), the measurement target as an evaluation target having a difference exceeding the threshold Correction is performed by multiplying the measured area value of the dot 81 by a predetermined correction coefficient. This is because, when the interval between the adjacent measurement dots 81 approaches smaller than the predetermined interval, the liquid of the measurement dots 81 penetrates into the ink absorption layer 43 and comes into contact with each other and mixes and penetrates. Or conversely, when the interval between adjacent measurement dots 81 is larger than a predetermined interval, the liquid in the process of forming adjacent measurement dots 81 does not interfere with each other in the ink absorbing layer 43. Since the apparent landing area of the measurement dot 81 to be evaluated becomes large due to spreading in a wide range in order to permeate the liquid, it is corrected to discharge the original measurement dot 81. This is done to obtain an approximate value for the quantity.

  In the present embodiment, when the difference between the adjacent measurement dots 81 exceeds a predetermined threshold with respect to the interval between the corresponding discharge nozzles, both sides of the measurement dots 81 to be evaluated are detected. The measurement dot 81 for which the measurement area 81 is to be corrected is determined by the size of the interval with respect to the measurement dot 81 to be evaluated. That is, when the interval between the measurement dot 81 to be evaluated and the measurement dot 81 adjacent on both sides thereof is larger than the interval between the corresponding discharge nozzles, the one with the larger distance The above correction processing is performed on the measurement dots 81. Further, when the interval between the measurement dot 81 to be evaluated and the measurement dot 81 adjacent on both sides thereof is smaller than the interval between the corresponding discharge nozzles, the smaller interval is closer. The above correction process is performed on the measurement dots 81. In addition, when the interval between the measurement dot 81 to be evaluated and the measurement dot 81 adjacent on both sides thereof is one far apart and the other is close to the distance between the corresponding discharge nozzles, The above-described correction process is performed on the measurement dot 81 having the smaller interval on the other side.

The apparent area of the measurement dots 81 when the interval between the adjacent measurement dots 81 is greatly separated from or close to the interval between the corresponding discharge nozzles is measured at a predetermined designed interval. This is larger than the case where the dot 81 is arranged. That is, when the measurement dot 81 to be measured is close to the adjacent measurement dot 81, the landed liquid fills the void cell 45 of the ink absorption layer 43 between the measurement dots 81 in a short time. Thereafter, the ink easily penetrates into the surrounding ink absorbing layer 43 and spreads. Further, when the measurement dot 81 to be measured is far away from the adjacent measurement dot 81, the landed liquid is not regulated by the adjacent measurement dots 81, and the ink is absorbed in the ink absorption layer 43. It becomes easy to spread so as to spread.
Due to such a phenomenon, the measurement dot 81 having an apparent landing area larger than that of the measurement dot 81 arranged with an appropriate interval is spaced from the design value of the measurement dot 81 adjacent to both sides. The measurement dot 81 area value corresponding to the original liquid discharge amount is obtained by the discharge amount evaluation method of the present embodiment that determines which measurement dot 81 is to be corrected depending on the amount of deviation. The inventor found.

  The landing area data of the measurement dot 81 corrected by the correction process is stored in the storage unit 175 again.

  As described above, according to the series of ejection amount evaluation methods described above, even when a transparent liquid having a high light transmittance or a liquid having a low solid content and a high permeability is used, the area of the liquid landing dot is accurately evaluated. Therefore, it is possible to contribute to maintaining stable quality of image recording by the droplet discharge device IJ.

  The embodiment of the present invention made by the inventor has been specifically described above, but the present invention is not limited to the above-described embodiment, and various modifications are made without departing from the scope of the present invention. Is possible.

  For example, the droplet (liquid) discharge device and the discharge amount evaluation method using the same according to the present invention have a special effect in a discharge nozzle provided in an inkjet head as a droplet discharge head by an inkjet method. For example, the present invention can be applied to other discharge nozzles such as a dispenser and a micropipette and a discharge inspection in a liquid discharge apparatus including the same.

  In the above embodiment, the piezoelectric element 2 is used as the pressurizing means for pressurizing the pressurizing chamber (cavity) 4 in the liquid droplet ejection head 20, but other methods may be used. For example, the diaphragm 3 may be deformed and pressurized using a coil and a magnet. In addition, the heater wiring may be arranged in the pressurizing chamber 4 and the heater wiring may be heated to vaporize the liquid or expand the gas contained in the liquid to apply pressure. In addition, the diaphragm 3 may be deformed and pressurized using electrostatic attraction and repulsion.

  In the above embodiment, an example in which the ejection amount is evaluated by the imaging unit 171 such as a CCD has been described. However, the test pattern 70 for evaluating the ejection amount can be recognized with the naked eye. Even with the naked eye recognition, it is possible to sufficiently perform discharge inspection such as determination of the presence or absence of missing dots due to nozzle clogging of the droplet discharge head 20 or the like.

  In addition, the above embodiment describes a liquid ejection apparatus mainly including a ejection amount evaluation unit, and a ejection amount evaluation method in a liquid ejection method using the same, and includes a printing apparatus and a recording apparatus. Needless to say, the disclosure includes a liquid ejection apparatus, a printing method, a recording method, a liquid ejection method, a printing system, a recording system, a computer system, a program, a storage medium storing the program, and the like.

  Further, the printer and the like as one embodiment have been described as above. However, the above embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

  In the above-described embodiment, as an example of the droplet discharge device IJ (inkjet printer), the droplet discharge head 20 including the discharge nozzle moves in a predetermined direction with respect to the recording medium P, and the liquid is discharged from the discharge nozzle. Although a so-called serial printer that discharges is mentioned, the present invention is not limited to this. For example, a line that discharges liquid from a discharge nozzle to a recording medium that moves in a predetermined direction with respect to a non-moving line head that includes discharge nozzles It may be a printer.

  DESCRIPTION OF SYMBOLS IJ ... Droplet discharge apparatus, P ... Recording medium, 2 ... Piezoelectric element, 3 ... Diaphragm, 4 ... Pressure chamber, 10 ... Control apparatus, 11 ... CPU, 12 ... Memory, 13 ... Drive control signal generation circuit, 14 DESCRIPTION OF SYMBOLS Ejection quantity evaluation circuit, 15 ... Liquid supply apparatus, 20 ... Droplet ejection head, 20B ... Nozzle block, 20G ... Nozzle block, 20R ... Nozzle block, 21-32 ... Ejection nozzle, 34 ... Bonding agent, 42 ... Base material , 43 ... Ink absorption layer, 45 ... Many void cells, 50 ... Discharge amount evaluation unit, 70 ... Test pattern, 81 ... Measuring dot, 101 ... Device mount, 102 ... Work stage, 103 ... Stage moving device, 104 ... Carriage 106 ... carriage moving device 108 ... first tank 109 ... second tank 110 ... third tank 171 ... imaging unit 172 ... optical system 173 ... illumination unit 174 ... discharge amount evaluation unit control circuit, 175 ... storage unit.

Claims (9)

In a droplet discharge device including a droplet discharge head having a plurality of discharge nozzles arranged at predetermined intervals,
A discharge step of discharging a liquid from the droplet discharge head onto a recording medium having an ink absorption layer to form a test pattern in which the liquid landing dots corresponding to the discharge nozzles are arranged in a matrix;
An evaluation step of evaluating an area of the landing dot in which the liquid spreads in the ink absorption layer, and evaluating a discharge amount of the liquid for each landing dot corresponding to the discharge nozzle based on the evaluation result. A discharge amount evaluation method,
The evaluation step includes a process of evaluating a landing position of the landing dot,
In the process of evaluating the landing position, a predetermined amount is set between a physical amount of the landing dot to be evaluated, the landing dot adjacent to the landing dot to be evaluated, and a physical amount between the corresponding discharge nozzles. A method for evaluating a discharge amount, comprising: a process of correcting a physical quantity measurement value of a landing dot having a difference exceeding the threshold by a predetermined correction coefficient when there is a difference exceeding the threshold. In the discharge amount evaluation method according to claim 1,
The ejection amount evaluation method, wherein the physical quantity is an interval. In the discharge amount evaluation method according to claim 1,
The ejection amount evaluation method, wherein the physical quantity is an area. In the discharge amount evaluation method according to claim 2 or 3,
When the interval or area between the landing dot to be evaluated and the landing dot adjacent on both sides thereof is larger than the interval between the corresponding discharge nozzles, the interval or area is far apart. The ejection amount evaluation method, wherein the correction process is performed only on one of the landing dots. In the discharge amount evaluation method according to claim 2 or 3,
When the distance or area between the landing dot to be evaluated and the landing dot adjacent to both sides thereof is one away from the corresponding interval between the discharge nozzles, and the other is close, A method for evaluating a discharge amount, wherein the correction process is performed only on a landing dot having a larger absolute amount. In the discharge amount evaluation method according to claim 2 or 3,
When the distance or area between the landing dot to be evaluated and the landing dot adjacent to both sides thereof is larger with respect to the interval between the corresponding discharge nozzles, and the other is smaller, A method for evaluating a discharge amount, comprising: performing the correction for a landing dot having a larger absolute amount. In the discharge amount evaluation method according to claim 2 or 3,
When the distance or area between the landing dot to be evaluated and the landing dot adjacent to both sides thereof is larger with respect to the interval between the corresponding discharge nozzles, and the other is smaller, A method for evaluating a discharge amount, wherein the correction is performed on a landing dot having a larger absolute amount. In the discharge amount evaluation method according to any one of claims 1 to 7,
In the evaluation step, the physical quantity and the landing position are evaluated by performing an imaging process for capturing an image of the landing dot and an analysis process for analyzing the image. In the discharge amount evaluation method according to any one of claims 1 to 8,
The discharge amount evaluation method according to claim 1, wherein the liquid is a transparent liquid having high light transmittance.

Images