JP2011183784A - Method for measuring amount of discharged droplet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring an amount of discharged droplets capable of measuring the amount of the discharged droplets with high precision by weight method. <P>SOLUTION: The amount of the discharged droplets is measured by jetting the droplets on a medium and weighing the medium after jetting the droplets. When the droplets are jetted on the medium, the droplets are jetted in such a predetermined droplet jet pattern that the small droplets to be measured and the large droplets larger than the droplets to be measured coexist with each other. The water vapor of the surroundings is saturated with the large droplets to suppress the vaporization of the small droplets to be measured. This suppresses a change of the weight due to the vaporization, and it is possible to measure the amount of the discharged droplets with high precision by the weight method. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a discharge droplet amount measuring method, and more particularly, to a discharge droplet amount measurement method for measuring a discharge droplet amount by a gravimetric method when a small-sized droplet is discharged.

  It is important that a droplet discharge head (inkjet head) used in an inkjet printer or the like can discharge droplets with a droplet amount determined from a nozzle. For this purpose, it is necessary to measure the amount of droplets discharged from the nozzle with high accuracy.

  As a method for measuring the amount of droplets discharged from the droplet discharge head, a method (weight method) is known in which droplets are discharged onto a medium and the weight is measured. The gravimetric method is widely used because measurement is simple.

  In the gravimetric method, in order to increase the accuracy, it is important to match the weight of the measured droplet to the weight of the actually ejected droplet as much as possible. For this purpose, it is important that all of the nozzles to be measured have the same amount of ejected droplets, so that all ejected droplets land on the medium and the droplet weight does not change due to evaporation.

  Therefore, in the past, in order to ensure that the discharge droplet volume is the same for all nozzles, it is possible to improve the head manufacturing accuracy and to stabilize discharge such as a preliminary waveform to prevent discharge instability (so-called latency) due to nozzle drying. Method is taken.

  In addition, in order to improve the landing resilience to the media, landing stabilization techniques such as waveform optimization (mist prevention) and flight distance adjustment have been taken.

  Also, measures such as optimizing media selection are taken to prevent evaporation. For example, it has been proposed to provide a thin plate-shaped coated member having ink repellency at the ink landing position, thereby reducing the surface area of the landing ink and reducing the weight change due to evaporation.

  In addition, in order to prevent evaporation, means such as using a non-volatile liquid, controlling humidity, and discharging into oil are taken.

JP 2007-75767 A

  Among the above measures, stabilization of ejection and stabilization of landing are important issues for improving printing quality. It becomes. In particular, in recent years, the amount of droplets has been reduced due to high-definition printing, and devices having a minimum droplet size of 2 pl or less have appeared. In such a situation, evaporation proceeds easily, and it is more difficult to perform highly accurate measurement by the gravimetric method.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a discharge droplet amount measuring method capable of measuring the discharge droplet amount with high accuracy by a gravimetric method.

  According to a first aspect of the present invention, in order to achieve the above object, in a method for measuring the amount of droplets discharged from a droplet discharge head capable of discharging droplets having different sizes, a droplet having a size to be measured and a measurement target A droplet ejection pattern composed of droplets of a size larger than the size to be measured, wherein the surrounding water vapor is saturated with droplets of a size larger than the size to be measured, and the size of the size to be measured A step of ejecting droplets on a predetermined medium with an array of droplet ejection patterns capable of suppressing evaporation of the droplets, a step of measuring the weight of the media after the droplet ejection, and the droplet ejection The weight of the previous medium, the weight of the medium after the droplet is deposited, the weight of a droplet having a size larger than the size to be measured that is ejected on the medium, and the droplet that is ejected on the medium Size to be measured Acquire each information of the number of droplets of a droplet having a larger size and the number of droplets of a droplet of the size to be measured that has been deposited on the medium, and perform the measurement based on the acquired information. A step of calculating a weight of a droplet of a target size, wherein the calculated weight is used as a discharge droplet amount of a droplet of the target size. The purpose is to provide.

  In the present invention, by drying droplets with a predetermined droplet ejection pattern, drying of droplets of a size to be measured is suppressed. Specifically, the surrounding water vapor is saturated with droplets of a size larger than the size to be measured, and evaporation of the size of the droplet to be measured is suppressed. Thereby, the change in weight due to evaporation can be suppressed, and the discharged droplet amount can be measured with high accuracy by the weight method. Moreover, the existing equipment can be used as it is without modifying the equipment.

  According to a second aspect of the present invention, in order to achieve the above object, the droplet having the size to be measured is a droplet having a volume of 4 pl or less, and the droplet having a size larger than the size to be measured. Is a droplet having a volume of 6 pl or more, and provides an ejection droplet amount measuring method according to claim 1.

  According to the present invention, a droplet having a size to be measured is composed of a droplet having a volume of 4 pl or less, and a droplet having a size larger than the size to be measured is composed of a droplet having a volume of 6 pl or more. . By disposing large droplets of 6 pl or more, the surrounding water vapor amount can be efficiently saturated, and the evaporation amount of minute droplets of 4 pl or less can be effectively suppressed.

  According to a third aspect of the present invention, in order to achieve the object, the droplet ejection pattern includes a region where a droplet having a size to be measured is suitable and a liquid having a size larger than the size to be measured. 3. The method for measuring the amount of ejected droplets according to claim 1 or 2, wherein the regions where the droplets are suitable are arranged alternately.

  According to the present invention, in the droplet ejection pattern, regions where droplets having a size to be measured are hit and regions where droplets having a size larger than the size to be measured are hit are alternately arranged. It is supposed to be configured. With such an arrangement, it is possible to visually check the droplet ejection pattern while suppressing evaporation of droplets of the size to be measured, and to cope with troubles such as unstable ejection.

  According to a fourth aspect of the present invention, in order to achieve the object, the droplet ejection pattern includes a region where a droplet having a size to be measured is suitable and a liquid having a size larger than the size to be measured. 4. The method for measuring the amount of discharged droplets according to claim 3, wherein the regions where the droplets are suitable are arranged alternately in a matrix.

  According to the present invention, a region where droplets having a size to be measured are suitable and a region where droplets having a size larger than the size to be measured are alternately arranged in a matrix pattern. It is set as the arrangement. As a result, it is possible to visually check the discharge instability to some extent while effectively suppressing the evaporation of the droplet of the size to be measured.

  According to a fifth aspect of the present invention, in order to achieve the object, the droplet ejection pattern includes a region where a droplet having a size to be measured is suitable and a liquid having a size larger than the size to be measured. 4. The discharge droplet amount measuring method according to claim 3, wherein the regions where the droplets are hit are arranged alternately in a line in a direction orthogonal to the nozzle arrangement direction.

  According to the present invention, a region where droplets having a size to be measured are suitable and a region where droplets having a size larger than the size to be measured are alternately arranged in a matrix pattern. It is set as the arrangement. Thereby, it is possible to visually confirm instability of ejection while suppressing evaporation of droplets of a size to be measured.

  In order to achieve the above object, the invention according to claim 6 is an area where droplets of a size to be measured are hit and an area where droplets of a size larger than the size to be measured are hit. The method for measuring the amount of discharged droplets according to claim 4 or 5 is provided.

  According to the present invention, the interval between the region where the droplet having the size to be measured is hit and the region where the droplet having a size larger than the size to be measured is hit is set to 1 mm or less. Thereby, the evaporation suppression effect by the droplet of a size larger than the size made into a measuring object can be heightened more.

  In the invention according to claim 7, in order to achieve the object, the droplet ejection pattern includes droplets having a size larger than the size to be measured around the droplet to be measured. The method for measuring the amount of ejected droplets according to claim 1 or 2 is provided.

  According to the present invention, the droplet ejection pattern is configured such that droplets having a size larger than the size to be measured are arranged around the droplet to be measured. Thereby, evaporation of the droplet of the size to be measured can be effectively suppressed.

  According to an eighth aspect of the present invention, in order to achieve the object, the droplet ejection pattern is an arrangement in which a droplet having a size to be measured is surrounded by a droplet having a size larger than the size to be measured. The method for measuring the amount of ejected droplets according to claim 7 is provided.

  According to the present invention, the droplet ejection pattern is arranged so as to surround a droplet having a size to be measured with a droplet having a size larger than the size to be measured. Thereby, evaporation of the droplet of the size to be measured can be more effectively suppressed.

  In order to achieve the above object, according to the ninth aspect of the present invention, in the droplet ejection pattern, the proportion of droplets having a size larger than the size to be measured is the proportion of droplets having the size to be measured. It is set so that it may become more than this, The discharge droplet amount measuring method as described in any one of Claims 1-8 provided.

  According to the present invention, the droplet ejection pattern is set such that the proportion of droplets having a size larger than the size to be measured is larger than the proportion of droplets having the size to be measured. Thereby, evaporation of the droplet of the size to be measured can be more effectively suppressed.

  According to a tenth aspect of the present invention, in order to achieve the above object, in the method for measuring the amount of droplets discharged from a droplet discharge head capable of discharging droplets of different sizes, the measurement target is set at the same position on a predetermined medium. A step of ejecting a droplet having a size larger than the size a predetermined number of times, a droplet of a size to be measured a predetermined number of times, a step of measuring the weight of the medium after the droplet is deposited, The weight of the medium before the droplet ejection, the weight of the medium after the droplet ejection, the weight of the droplet having a size larger than the size to be measured, which is ejected onto the medium, Information on the number of droplets having a size larger than the size to be measured and the number of droplets having the size to be measured deposited on the medium is acquired. , Based on each acquired information A step of calculating a weight of a droplet having a size to be measured, wherein the calculated weight is used as a discharge droplet amount of a droplet having a size to be measured. Provide a measuring method.

  In the present invention, a droplet having a size larger than the size to be measured is ejected a predetermined number of times at the same position on the medium, and then a droplet having a size to be measured is ejected a predetermined number of times to obtain the measurement target. Suppresses evaporation of size droplets. Thereby, the change in weight due to evaporation can be suppressed, and the discharged droplet amount can be measured with high accuracy by the weight method. Moreover, the existing equipment can be used as it is without modifying the equipment.

  According to an eleventh aspect of the present invention, in order to achieve the above object, in a method for measuring a droplet amount of a droplet discharge head capable of discharging droplets having different sizes, the measurement target is set at the same position on a predetermined medium. A step of alternately ejecting droplets of a size larger than the size and a droplet of a size to be measured a predetermined number of times, a step of measuring the weight of the medium after the droplet ejection, and the droplet ejection The weight of the medium before dropping, the weight of the medium after droplet dropping, the weight of a droplet having a size larger than the size to be measured that has been dropped on the medium, and the droplet hitting on the medium Acquire each information of the number of droplets of a size larger than the size to be measured, and the number of droplets of the size of the droplet to be measured deposited on the medium The measurement object based on the information And a step of calculating a weight of a droplet having a size to be measured, wherein the calculated weight is used as a discharge droplet amount of a droplet having a size to be measured. To do.

  In the present invention, droplets of a size larger than the size to be measured and droplets of the size to be measured are alternately ejected a predetermined number of times at the same position on the medium, and Suppresses evaporation. Thereby, the change in weight due to evaporation can be suppressed, and the discharged droplet amount can be measured with high accuracy by the weight method. Moreover, the existing equipment can be used as it is without modifying the equipment.

  In the invention according to claim 12, in order to achieve the object, the number of droplets ejected with a size larger than the size to be measured is larger than the number of droplets ejected with the size to be measured. The discharge droplet amount measuring method according to claim 10 or 11, wherein the number of droplets is set so as to increase.

  According to the present invention, the number of droplets having a size larger than the size to be measured is set to be larger than the number of droplets having a size to be measured. Thereby, evaporation of droplets of a size to be measured can be suppressed more effectively.

  In the invention according to claim 13, in order to achieve the object, the weight of the droplet having a size larger than the size to be measured is larger than the size to be measured on the predetermined medium. The droplets are ejected a predetermined number of times, the weight of the media after the droplet ejection is measured, and the droplets having a size larger than the measured weight of the media after the droplet ejection and the size to be measured The method according to claim 1, wherein the method is obtained based on the number.

  According to the present invention, the weight of a droplet having a size larger than the size to be measured is measured by a gravimetric method. Thereby, it becomes the same as the measurement conditions of the droplet of the size made into a measuring object, and can improve a measurement precision further.

  According to the present invention, the amount of droplets discharged from the droplet discharge head can be measured with high accuracy by the weight method.

The perspective view which shows schematic structure of the recording part of an inkjet recording device Plane perspective view of nozzle surface of inkjet head Longitudinal sectional view showing the schematic structure inside the inkjet head A block diagram showing a schematic configuration of a head drive control unit for controlling the drive of an inkjet head The figure which shows an example of the drive waveform in the case of changing the size of a droplet by changing the peak value of the discharge pulse incorporated within 1 recording period. The figure which shows the example of the drive waveform in the case of changing the size of a droplet by changing the number of the discharge pulses to incorporate Flowchart showing the first embodiment of the procedure for measuring the discharge droplet amount Diagram showing an example of a droplet ejection pattern The figure which shows an example of the arrangement | sequence of a droplet when performing a droplet by mixing a small droplet and a large droplet Flowchart showing the second embodiment of the procedure for measuring the discharge droplet amount

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a method for measuring the amount of discharged droplets according to the present invention will be described in detail with reference to the accompanying drawings.

  In this example, a case where the amount of discharged droplets of an inkjet head (droplet discharge head) mounted on the inkjet recording apparatus is measured will be described as an example.

<< Schematic configuration of inkjet recording apparatus >>
FIG. 1 is a perspective view illustrating a schematic configuration of a recording unit of an ink jet recording apparatus.

  An inkjet recording apparatus 10 shown in the figure is a line printer that records an image on a medium 12 by a single pass method, and is equipped with an inkjet head 20 (line head) corresponding to the media width.

  The medium 12 is held on the transport table 14 and is transported along a predetermined transport path.

  The transport table 14 is slidably provided on the pair of rails 16, and a horizontal media holding surface 14A is formed on the upper surface thereof. The medium 12 is held by suction on a medium holding surface 14A formed on the upper surface of the transport table 14 (for example, held by vacuum suction or electrostatic suction).

  The transport table 14 is provided with a nut portion 14B. The nut portion 14 </ b> B is screwed to a screw rod 18 disposed in parallel with the rail 16. The screw rod 18 is connected to a motor (not shown) and is driven by this motor to rotate forward and backward. As the screw rod 18 rotates, the transfer table 14 moves back and forth on the rail 16.

  The inkjet head 20 is composed of a line head and is disposed on the conveyance path of the medium 12. A nozzle surface is formed on the lower surface of the inkjet head 20, and ink droplets are ejected vertically downward from the nozzle formed on the nozzle surface.

  In the recording unit configured as described above, the medium 12 is sucked and held on the medium holding surface 14A of the transfer table 14 and is conveyed along a predetermined conveyance path. Then, it passes under the inkjet head 20 during the conveyance process, and ink droplets are ejected onto the surface (upper surface) during the passage, and an image is recorded on the surface.

<Inkjet head configuration>
As described above, the inkjet head 20 is configured by a line head corresponding to the width of the medium 12.

  FIG. 2 is a plan perspective view of the nozzle surface of the inkjet head.

  As shown in the figure, in the inkjet head 20 of the present embodiment, nozzles 22 are arranged on a nozzle surface 20A in a two-dimensional matrix (so-called matrix head). More specifically, a plurality of nozzles 22 are arranged at a constant pitch in a direction inclined by a predetermined angle with respect to the transport direction of the medium 12 to form a nozzle array, and the nozzle array is orthogonal to the transport direction of the medium 12. In this direction, a large number are arranged at a constant pitch.

  By adopting such an arrangement configuration, it is possible to reduce the substantial interval between the nozzles 22 projected in the longitudinal direction of the head (the direction orthogonal to the conveyance direction of the medium 12), and to increase the density of the nozzles 22. be able to.

  Each nozzle 22 communicates with a pressure chamber 26 via a nozzle channel 24 (see FIG. 3).

  FIG. 3 is a longitudinal sectional view showing a schematic structure inside the ink jet head.

  As shown in the figure, the pressure chamber 26 is formed as a rectangular parallelepiped space, and the nozzle channel 24 is communicated with one corner of the bottom surface. The nozzle flow path 24 extends vertically downward from the pressure chamber 26 and communicates with the nozzle 22.

  The ceiling wall surface of the pressure chamber 26 includes a diaphragm 28 and is formed to be deformable in the vertical direction. A piezoelectric element (piezo element) 30 as an actuator is attached on the vibration plate 28, and the vibration plate 28 is deformed in the vertical direction by the piezoelectric element 30. The diaphragm 28 is deformed in the vertical direction, whereby the volume of the pressure chamber 26 expands and contracts, and ink droplets are ejected from the nozzles 22.

  The piezoelectric element 30 is driven by applying a predetermined drive voltage between an individual electrode (not shown) provided on the piezoelectric element 30 and a diaphragm 28 acting as a common electrode.

  An individual supply channel 32 for supplying ink to the pressure chamber 26 is communicated with one corner of the ceiling wall of the pressure chamber 26 (diagonal position of the nozzle channel 24). The individual supply channels 32 are connected to a common supply channel 34 for supplying ink to each individual supply channel 32.

  The common supply flow path 34 is provided for each row of nozzles 22 (see FIG. 2) arranged with a predetermined inclination with respect to the conveyance direction of the medium 12. Ink is supplied from the common supply channel 34 through the individual supply channel 32 to the pressure chambers 26 of the nozzles 22 belonging to each row.

  The common supply channel 34 of each row is in communication with an ink supply channel (not shown), and the ink supply channel is in communication with an ink supply port (not shown). Ink from the ink tank is supplied to the ink supply port. Then, the ink supplied to the ink supply port is supplied to the common supply flow path 34 of each column via the ink supply flow path, and further supplied to each pressure chamber 26 via the individual supply flow path 32.

  An individual recovery passage 36 is communicated with the nozzle passage 24 in the middle of the passage. The individual recovery flow path 36 communicates with the nozzle flow path 24 at a position near the nozzle 22, extends horizontally, and communicates with the common recovery flow path 38 at the tip.

  Similar to the common supply flow path 34, the common recovery flow path 38 is provided in units of rows of nozzles 22 arranged with a predetermined inclination with respect to the conveyance direction of the medium 12. The common recovery flow path 38 of each row communicates with an ink recovery flow path (not shown), and the ink recovery flow path communicates with an ink recovery port (not shown).

  A part of the ink flowing through each nozzle channel 24 flows to the individual recovery channel 36 and is recovered to the common recovery channel 38. Then, the ink is recovered from each common recovery channel 38 to the ink tank through the ink recovery channel and the ink recovery port. That is, in the inkjet head 20 of this example, the ink is circulated and supplied.

<< Configuration of Inkjet Head Drive Control Unit >>
FIG. 4 is a block diagram illustrating a schematic configuration of a head drive control unit that controls driving of the inkjet head.

  As shown in the figure, the head drive control unit 100 includes a controller 112, an image input unit 114, an image processing unit 116, a data storage unit 118, an operation unit 120, a head driver 122, and the like.

  The controller 112 is composed of a microcomputer, and executes a predetermined control program to control each part in an integrated manner.

  The image input unit 114 captures image data (for example, image data in RGB format) to be recorded on the medium 12.

  The image processing unit 116 performs necessary signal processing such as color conversion processing and halftone processing on the image data captured from the image input unit 114 to generate dot data for print control.

  The data storage unit 118 stores various data necessary for control. Droplet pattern data and the like for measuring the amount of discharged droplets to be described later are stored in the data storage unit 118.

  The operation unit 120 includes a keyboard or the like. Input of information necessary for control is performed using the operation unit 120.

  The head driver 122 generates a signal for driving each actuator (piezoelectric element) 30 of the inkjet head 20 based on the dot data generated by the image processing unit 116. Then, a signal (driving signal) generated by the head driver 122 is applied to each actuator 30 of the inkjet head 20, whereby an ink droplet is ejected from the corresponding nozzle 22.

<Driving method of inkjet head>
As described above, the inkjet head 20 ejects ink droplets from each nozzle by applying a predetermined drive signal to an actuator (piezoelectric element) provided corresponding to each nozzle. This drive signal is applied at a constant recording cycle, and the size (dot diameter) of a droplet ejected onto a medium can be changed by changing the drive waveform.

  FIG. 5 is a diagram showing an example of a drive waveform when the droplet size is changed by changing the peak value of the ejection pulse incorporated within one recording cycle.

  FIG. 5A shows a driving waveform when a small droplet is ejected, FIG. 5B shows a driving waveform when a medium droplet is ejected, and FIG. 4C shows a large liquid. The drive waveform in the case of hitting a drop is shown. As shown in the figure, the size of the droplet to be ejected can be changed by changing the peak value (voltage) of the ejection pulse. In this way, by enabling droplets of different sizes to be ejected, gradation recording can be performed and a high-quality image can be recorded.

  FIG. 6 is a diagram illustrating an example of a driving waveform in the case where the droplet size is changed by changing the number of ejection pulses to be incorporated.

  FIG. 4A shows a drive waveform when discharging a small size, FIG. 4B shows a drive waveform when discharging a medium size, and FIG. 4C shows a drive waveform when discharging a large droplet. Is shown.

  As shown in the figure, the ejection pulses are incorporated at regular intervals. Then, by incorporating only one, a small-sized droplet, by incorporating two, a medium-sized droplet, and by incorporating four, a large-sized droplet is ejected.

  As shown in FIG. 6, when the ejection pulse is incorporated so that the peak value gradually increases, the ink droplet ejected later catches up with the previously ejected ink droplet and is landed on the recording medium in a single droplet state. (So-called aerial coalescence).

  In addition, it is also possible to change the size of the droplet to be ejected by making the crest value of each ejection pulse constant and changing the number of ejection pulses incorporated. In this case, the droplets sequentially land at the same location, and dots of a predetermined size are formed.

  As described above, the size of the droplet in the present invention includes both the concept of indicating the size of one particle in the air and the size of when landing.

<Measurement method of ejected droplet amount>
The measurement of the discharge droplet amount is performed by a weight method. In the gravimetric method, drying of discharged droplets has a great influence on measurement accuracy. This is particularly noticeable when measuring small-sized droplets (for example, droplets having a volume of 4 pl or less).

  Therefore, in the present embodiment, when measuring the amount of ejected droplets of small-sized droplets, small-sized droplets (small droplets) and large-sized droplets (large droplets) are mixed. Drops and saturates the surrounding water vapor with large droplets, relatively suppressing evaporation of small droplets.

<First Embodiment>
FIG. 7 is a flowchart showing the first embodiment of the procedure for measuring the discharge droplet amount.

  First, the ejection amount of large droplets used for evaporation suppression is measured (step S10).

  Since the measurement value of a large droplet is stable even by the gravimetric method, it can be measured with high accuracy by itself.

  Therefore, first, the discharge amount (weight) of large droplets is measured by the weight method. The measurement is performed, for example, by ejecting a large droplet from each nozzle of the inkjet head 20 a predetermined number of times while the medium 12 is stationary. Droplets (large droplets) ejected from the nozzle are ejected at the same location. After the droplet ejection, the weight of the medium 12 is measured, and the ejection droplet amount is calculated from the weight of the medium alone and the number of droplet ejection. That is, since the difference between the weight of the medium alone and the weight of the medium 12 after droplet ejection is the total ejection droplet volume, the ejection droplet volume can be obtained by dividing this by the total ejection volume. . For example, when the number of nozzles 22 provided on the nozzle surface 20A is N and S droplets are ejected from each nozzle 22, the weight of the medium alone is W0, and the weight of the medium after droplet ejection is W1. The discharged droplet amount X is X = (W1−W0) / N × S.

  Next, the weight W0 of the single medium is measured (step S12).

  Note that it is preferable to use a non-penetrating material for the medium 12 in order to suppress evaporation.

  In addition, when discharging in a large amount, it is preferable to use a plastic tray in order to prevent dripping.

  Next, a droplet is ejected onto the medium with a predetermined droplet ejection pattern (step S14).

  This droplet ejection pattern is a pattern in which small droplets to be measured are mixed with the large droplets for suppressing evaporation, and the surrounding water vapor is saturated with the large droplets. Suppresses evaporation.

  FIG. 8 is a diagram showing an example of a droplet ejection pattern.

  FIG. 4A shows a configuration in which small droplets to be measured and large droplets for suppressing evaporation are mixed and arranged. That is, the large droplet is arranged close to the periphery of the small droplet. For example, as shown in FIG. 9A, the large droplets are arranged on the front, rear, right and left of the small droplets. Alternatively, in addition to the front, rear, left and right, they are arranged at an oblique position and are completely enclosed around the small droplet.

  As described above, by arranging the large droplet for suppressing evaporation close to the small droplet to be measured, evaporation of the small droplet can be effectively suppressed.

  In FIG. 6B, the area [Small] for ejecting small droplets to be measured and the area [Large] for ejecting large droplets for suppressing evaporation are transported in the direction of the medium 12 (inkjet head 20). Are formed with a constant width along a direction perpendicular to the nozzle arrangement direction in FIG. 1, and are alternately arranged at a predetermined interval in a direction orthogonal to the conveyance direction of the media 12 (medium of the media). Striped pattern in the direction along the conveying direction (vertical striped pattern)).

  By adopting such a droplet ejection pattern, in addition to suppressing evaporation of small droplets, it becomes possible to visually confirm the droplet ejection pattern that has been deposited on the medium 12, and also to troubles such as unstable ejection. It will be possible to respond.

  FIG. 6C shows a configuration in which a region [S] for ejecting a small droplet to be measured and a region [L] for ejecting a large droplet for suppressing evaporation are arranged in a matrix. is there.

  When priority is given to evaporation suppression, as shown in FIG. 8A, a droplet ejection pattern in which small droplets to be measured and large droplets for evaporation suppression are mixed and employed is employed. Is preferred. On the other hand, in order to deal with troubles such as unstable ejection, it is preferable to employ a vertical stripe pattern as shown in FIG. FIG. 3C shows a pattern having an intermediate property between the two. That is, it is possible to visually confirm problems such as ejection instability from the droplet ejection pattern while ensuring the function of suppressing evaporation.

  FIG. 6D shows a droplet ejection pattern when nozzles for ejecting small droplets to be measured and nozzles for ejecting large droplets for suppressing evaporation are alternately set. In this case, rows of large droplets and rows of small droplets are alternately formed in a direction orthogonal to the conveyance direction of the medium 12.

  Also in this case, it is possible to visually confirm problems such as unstable ejection from the droplet ejection pattern while suppressing evaporation of small droplets.

  Note that a plurality of nozzles for discharging small droplets to be measured and nozzles for discharging large droplets for suppressing evaporation may be alternately set. Further, the ratio may be changed. For example, the configuration may be such that nozzles that eject large droplets are 2 and nozzles that eject small droplets are 1, and the nozzles are alternately set. In this case, it becomes the structure by which the row | line | column of a small droplet is arrange | positioned every 2 rows.

  FIG. 4E shows that a region [Small] for ejecting a small droplet to be measured and a region [Large] for ejecting a large droplet for suppressing evaporation are orthogonal to the transport direction of the medium 12. Are formed with a constant width along the direction of conveyance of the medium 12 and arranged alternately at a constant interval (a stripe pattern in a direction perpendicular to the medium conveyance direction (horizontal stripe pattern). ).

  As described above, the area [Small] for ejecting small droplets to be measured and the area [Large] for ejecting large droplets for suppressing evaporation are alternately arranged along the transport direction of the medium 12. Also, the evaporation of small droplets can be suppressed.

  In this case, each nozzle continuously discharges large droplets and then repeatedly discharges small droplets to form a droplet ejection pattern.

  In the example shown in the figure, the width of the region [Small] for ejecting a small droplet to be measured and the region [Large] for ejecting a large droplet for suppressing evaporation (in the transport direction of the medium 12). The width) is the same, but a difference may be provided between the two. In this case, the width of the region where the large droplet is ejected is made wider than the width of the region where the small droplet is ejected. Thereby, the effect of suppressing the evaporation of small droplets can be further enhanced.

  FIG. 5F shows a droplet ejection pattern constituted by alternately ejecting small droplets to be measured and large droplets for suppressing evaporation.

  In this manner, by alternately ejecting small droplets to be measured and large droplets for suppressing evaporation, droplets can be uniformly ejected from each nozzle while obtaining an evaporation suppressing effect. it can.

  FIG. 4G shows a configuration in which a region for ejecting a large droplet for suppressing evaporation is formed in a frame shape, and a region for ejecting a small droplet to be measured is formed in the frame. .

  In this manner, by enclosing the region where the small droplets to be measured are ejected with the large droplets, evaporation of the small droplets can be effectively suppressed.

  FIG. 11 (h) shows a matrix structure in which a region for ejecting large droplets for suppressing evaporation is formed in a frame shape, and a region for ejecting small droplets to be measured is formed in the frame. It is the thing of the structure arrange | positioned in the shape.

  Thus, by dividing the droplet ejection region into small blocks and surrounding the periphery with large droplets, evaporation of the small droplets can be more effectively suppressed.

  In this way, various patterns can be set for the droplet ejection pattern, such as the purpose (whether or not evaporation suppression is given top priority, whether or not the droplet ejection pattern can be visually checked), and the characteristics of the head. Depending on the arrangement of the nozzles, the wettability of the media 12, the evaporation characteristics, and the like, it can be selected as appropriate.

  In addition, when dividing | segmenting the area | region which ejects a small droplet, and the area | region which ejects a large droplet, it is preferable that the space | interval d of both is 1 mm. This is because if it exceeds 1 mm, the effect of suppressing evaporation by large droplets is reduced.

  The droplet ejection pattern is preferably set so that the proportion of large droplets for suppressing evaporation is larger than the proportion of small droplets to be measured. That is, the ratio of the total volume of small droplets to the total volume of small droplets ([total volume of large droplets] / [total volume of small droplets]) is set to exceed 1. Thereby, evaporation of a small droplet can be suppressed effectively.

  Information on the droplet ejection pattern is stored in the data storage unit 118. The controller 112 reads the droplet ejection pattern information from the data storage unit 118 when measuring the amount of ejected droplets, and deposits droplets on the medium according to the read droplet ejection pattern information.

  A plurality of droplet ejection patterns as described above may be prepared so that the user can arbitrarily select them. Alternatively, a user inputs necessary information (information on ink to be used, media information, head information, etc.) or the controller 112 automatically obtains the optimum droplet ejection pattern by the controller 112 automatically. You may make it select with.

  After droplets are deposited on the medium according to the droplet ejection pattern, the media is collected, and the weight W1 of the media on which the droplets are deposited is measured (step S16).

  Then, the weight W1 of the obtained medium 12 after droplet ejection, the weight W0 of the medium alone, the ejection droplet amount LX of the large droplet, the number of droplet ejection LN of the large droplet, From the droplet ejection number SS, the ejection droplet amount SX (weight) of the small droplet is calculated (step S18).

  Here, the information on the number LS of large droplets and the number SS of small droplets are obtained from the used droplet ejection pattern.

  The discharge droplet amount SX of small droplets can be obtained by SX = [(W1-W0) -LS × LX] / SS.

  In other words, the difference (W1−W0) between the weight W1 of the medium 12 after droplet ejection and the weight W0 of the single medium is the total ejection droplet amount, of which the total ejection droplet amount of large droplets is (LS × LX), the total discharge droplet amount of the small droplets is [(W1-W0) -LS × LX]. Since the number of droplets ejected by SS is SS, the number of droplets ejected SS is divided by subtracting the number of droplets ejected SS from the total ejected droplet amount [(W1-W0) -LS × LX]. The discharge droplet amount SX can be obtained. Here, since the amount of ejected droplets is weight, it is converted into a volume as necessary.

  As described above, the discharge droplet amount of a small droplet (small droplet) to be measured can be obtained.

  As described above, in the method for measuring the amount of ejected droplets according to the present embodiment, a droplet having a size to be measured and a droplet for suppressing evaporation are mixed and ejected onto a medium, and the measurement target The amount of discharged liquid droplets of the size of Thereby, evaporation can be suppressed and the discharge droplet amount of the droplet of the size to be measured can be measured with high accuracy.

  In the above embodiment, the amount of ejected droplets of large droplets for suppressing evaporation is measured before droplets are ejected on a medium in a predetermined droplet ejection pattern. The measurement of the amount of ejected droplets of large droplets may be performed after droplets are ejected in a predetermined droplet ejection pattern. That is, the information on the ejection droplet amount of the large droplet for suppressing evaporation may be acquired before the ejection droplet amount of the droplet having the size to be measured is calculated.

  Further, in this embodiment, the discharge droplet amount of the large droplet for suppressing evaporation is measured by the gravimetric method, but the method for obtaining the discharge droplet amount of the large droplet for suppressing evaporation is not limited to this. It can be measured using other known methods.

  Further, in the present embodiment, it is configured to eject a large droplet for suppressing evaporation, but the size of the droplet used for suppressing evaporation is not limited to this, and the medium size or extra large size is used. Droplets of these sizes can be used as evaporation suppression droplets. Further, a plurality of sizes of droplets can be used as droplets for suppressing evaporation. These are preferably selected as appropriate based on the composition of the ink and the performance of the head.

  Further, in the gravimetric method, since the accuracy of the balance used greatly affects the measurement accuracy, it is preferable to set a droplet ejection pattern (total discharged droplet amount) according to the accuracy of the balance used.

  In addition, if there is a nozzle that has a defective discharge, the measurement accuracy is greatly affected. Therefore, it is preferable to check a nozzle that has a defective discharge in advance.

  In the above embodiment, the liquid droplets are discharged from all the nozzles. However, it is not always necessary to discharge the liquid droplets from all the nozzles, and the liquid droplets may be selectively discharged.

  It is to be noted that the present invention is intended to perform highly accurate measurement by suppressing the evaporation of the discharged droplets, and therefore, when measuring the amount of discharged droplets having a size that causes evaporation. It works particularly effectively. In particular, it works effectively when measuring the amount of ejected droplets of micro droplets of 4 pl or less.

<Example>
In an inkjet head capable of ejecting large-sized droplets (large droplets) and small-sized droplets (small droplets), an experiment was performed to measure the amount of small droplets ejected by the above method.

  A matrix head having 2000 nozzles was used as an inkjet head to be measured.

-Large droplet discharge droplet amount First, the large droplet discharge droplet amount was measured. The measurement was performed by a gravimetric method. Specifically, 2000 large droplets were ejected from each nozzle of the inkjet head while the media was stationary, and the weight of the media after ejection was measured. For the media, glossy ink jet paper was used. The measured value XL was 6.0 ± 0.2 pl.

-Weight of media alone In consideration of availability and ink wettability, glossy paper for inkjet was used.

-Droplet onto the medium A nozzle that discharges large droplets and nozzles that discharge small droplets were alternately set, and a droplet-dropping pattern constituted by discharging 2000 droplets from each nozzle was used. Therefore, the number of nozzles for ejecting large droplets is 1000, the number of nozzles for ejecting small droplets is also 1000, the number of droplets ejected by large droplets is 1000 × 2000, and the number of droplets ejected by small droplets is also 1000 × 2000.

  A large droplet line and a small droplet line of a predetermined length are formed on the medium after droplet ejection along the medium conveyance direction, and the large droplet line and the small droplet line are formed. Lines are alternately formed in a direction orthogonal to the media conveyance direction.

-Calculation of total discharge droplet amount The weight of the media after droplet ejection was measured, and the total discharge droplet amount (weight) was determined from the difference from the weight of the media obtained in advance. The total discharge droplet amount was 0.016 ± 0.002 g.

・ Calculation of ejected droplet volume of small droplets Based on the previously determined ejected droplet volume of large droplets, the number of droplets ejected by large droplets, and the number of droplets ejected by small droplets, the droplet ejection liquid The drop volume was calculated. The calculation result was 2.0 ± 0.1 pl.

  When the measurement was performed under different conditions, the measured value was stabilized by setting the total discharge droplet amount to 0.01 g or more.

  Therefore, it is preferable to set the droplet ejection pattern so that the total ejection droplet amount is 0.01 g or more. In addition, as described above, it is preferable to set a larger ratio of ejecting large droplets for suppressing evaporation than a ratio of ejecting droplets of a size to be measured.

  In the gravimetric method, since the measurement accuracy varies depending on the accuracy of the scale used, it is preferable to determine the droplet ejection pattern in accordance with the accuracy of the scale used, assuming the total amount of droplets to be discharged.

<Second Embodiment>
FIG. 10 is a flowchart showing a second embodiment of the procedure for measuring the discharge droplet amount.

  The steps other than the step of discharging the droplet to be measured on the medium (step S24) are the same as the measurement procedure of the first embodiment described above.

  Therefore, here, only the step of ejecting the droplet to be measured on the medium will be described.

  Also in the present embodiment, a droplet having a size to be measured and a large droplet for suppressing evaporation are mixed and ejected onto the medium.

  However, in the present embodiment, droplets are ejected at the same location while the medium 12 is stationary.

  In droplet ejection, droplets for suppressing evaporation and droplets of a size to be measured are alternately ejected. In this case, a droplet for suppressing evaporation is first ejected. Thereby, droplets can be uniformly ejected.

  The droplet is ejected a certain number of times, and the medium 12 is collected after the droplet ejection. Then, the weight of the collected medium 12 is measured (step S26), and the ejection droplet amount of the droplet of the size to be measured is calculated (step S28).

  Thus, by evaporating a small droplet to be measured on a large droplet for suppressing evaporation, evaporation of the small droplet can be suppressed. Thereby, the discharge droplet amount of small droplets can be calculated with high accuracy by the weight method.

  The mode of ejecting large droplets for suppressing evaporation and small droplets to be measured is not limited to this. In addition, for example, it may be repeated a plurality of times that a large droplet for suppressing evaporation is continuously ejected a plurality of times and then a small droplet to be measured is continuously ejected a plurality of times. By performing droplet ejection in this manner, the evaporation suppression effect can be further enhanced.

  In addition, a nozzle that discharges a small droplet to be measured and a large droplet to suppress evaporation are disposed so that the large droplet for suppressing evaporation is ejected adjacent to the small droplet to be measured. It is also possible to set the nozzles to be ejected and to successively eject the target droplets from each nozzle a predetermined number of times.

  As described above, the mode of ejecting the large droplet for suppressing evaporation and the small droplet to be measured can take various modes, and can be selected and used as appropriate according to the ink to be used and the purpose. be able to. In addition, when the droplet discharge is affected by crosstalk, it is preferable to set the droplet discharge conditions in consideration of the crosstalk.

  In the case of this example, the measured value was stable when the total discharge droplet amount was 0.01 g or more. Accordingly, it is preferable to set the number of droplets to be measured and the droplets for suppressing evaporation so that the total discharge droplet amount is 0.01 g or more. Moreover, it is preferable to determine the number of droplets to be ejected according to the accuracy of the scale used, assuming the total amount of ejected droplets.

  Moreover, although the said embodiment demonstrated the case where the droplet discharge amount of a line head was measured as an example, the kind of inkjet head (droplet discharge head) made into a measuring object is not limited to this. . The present invention can be similarly applied to the case where the amount of droplets discharged from a shuttle type head is measured. In the above embodiment, the case of measuring the discharge droplet amount of a so-called matrix head has been described as an example. However, the arrangement of the nozzles is not limited to this.

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 12 ... Media, 14 ... Conveying table, 14A ... Media holding surface, 14B ... Nut part, 16 ... Rail, 18 ... Screw rod, 20 ... Inkjet head, 20A ... Nozzle surface, 22 ... Nozzle, 24 DESCRIPTION OF SYMBOLS ... Nozzle flow path, 26 ... Pressure chamber, 28 ... Diaphragm, 30 ... Actuator (piezoelectric element (piezo element)), 32 ... Individual supply flow path, 34 ... Common supply flow path, 36 ... Individual recovery flow path, 38 ... Common recovery flow path, 100 ... head drive control unit, 112 ... controller, 114 ... image input unit, 116 ... image processing unit, 118 ... data storage unit, 120 ... operation unit, 122 ... head driver

Claims (13)

In the method for measuring the amount of droplets discharged from a droplet discharge head capable of discharging droplets of different sizes,
A droplet ejection pattern composed of droplets having a size to be measured and droplets having a size larger than the size to be measured, and surrounding droplets having a size larger than the size to be measured A step of saturating water vapor and ejecting droplets on a predetermined medium with an ejection pattern of an array capable of suppressing evaporation of droplets of the size to be measured;
Measuring the weight of the media after the droplet ejection;
The weight of the medium before the droplet ejection, the weight of the medium after the droplet ejection, the weight of the droplet having a size larger than the size to be measured, which is ejected onto the medium, Information on the number of droplets having a size larger than the size to be measured and the number of droplets having the size to be measured deposited on the medium is acquired. A step of calculating the weight of the droplet of the size to be measured based on each acquired information;
And the calculated weight is used as a discharge droplet amount of a droplet of the size to be measured.   The droplet having a size to be measured is a droplet having a volume of 4 pl or less, and the droplet having a size larger than the size to be measured is a droplet having a volume of 6 pl or more. The method for measuring an ejected droplet amount according to claim 1.   The droplet ejection pattern has a configuration in which regions where droplets of the size to be measured are suitable and regions where droplets of a size larger than the size to be measured are alternately arranged. The discharge droplet amount measuring method according to claim 1 or 2.   In the droplet ejection pattern, regions where droplets of the size to be measured are suitable and regions where droplets of a size larger than the size to be measured are alternately arranged in a matrix. The method for measuring the amount of discharged droplets according to claim 3, wherein the method is a configuration.   In the droplet ejection pattern, a region where a droplet having a size to be measured is hit and a region where a droplet having a size larger than the size to be measured is hit are orthogonal to the nozzle arrangement direction. 4. The method for measuring the amount of discharged droplets according to claim 3, wherein the droplets are alternately arranged in a line in the direction.   5. An interval between a region where a droplet having a size to be measured is suitable and a region where a droplet having a size larger than the size to be measured is suitable is 1 mm or less. Or 5. A method for measuring an ejected droplet amount according to 5.   The droplet ejection pattern has a configuration in which droplets having a size larger than the size to be measured are arranged around the droplet having the size to be measured. Of measuring the amount of discharged droplets.   8. The ejected droplet according to claim 7, wherein the droplet ejection pattern is an arrangement in which a droplet having a size to be measured is surrounded by a droplet having a size larger than the size to be measured. Quantity measuring method.   The droplet ejection pattern is set so that a ratio of droplets having a size larger than the size to be measured is larger than a ratio of droplets having a size to be measured. The discharge droplet amount measuring method according to any one of 1 to 8. In the method for measuring the amount of droplets discharged from a droplet discharge head capable of discharging droplets of different sizes,
A step of ejecting a droplet having a size larger than the size to be measured at the same position on a predetermined medium a predetermined number of times, and then ejecting a droplet having a size to be measured a predetermined number of times;
Measuring the weight of the media after the droplet ejection;
The weight of the medium before the droplet ejection, the weight of the medium after the droplet ejection, the weight of the droplet having a size larger than the size to be measured, which is ejected onto the medium, Information on the number of droplets having a size larger than the size to be measured and the number of droplets having the size to be measured deposited on the medium is acquired. A step of calculating the weight of the droplet of the size to be measured based on each acquired information;
And the calculated weight is used as a discharge droplet amount of a droplet of the size to be measured. In the method for measuring the amount of droplets discharged from a droplet discharge head capable of discharging droplets of different sizes,
A step of alternately ejecting droplets of a size larger than the size to be measured and droplets of the size to be measured at the same position on a predetermined medium a predetermined number of times;
Measuring the weight of the media after the droplet ejection;
The weight of the medium before the droplet ejection, the weight of the medium after the droplet ejection, the weight of the droplet having a size larger than the size to be measured, which is ejected onto the medium, Information on the number of droplets having a size larger than the size to be measured and the number of droplets having the size to be measured deposited on the medium is acquired. A step of calculating the weight of the droplet of the size to be measured based on each acquired information;
And the calculated weight is used as a discharge droplet amount of a droplet of the size to be measured.   The number of droplets ejected with a droplet having a size larger than the size to be measured is set to be larger than the number of droplets ejected with a droplet having a size to be measured. 11. A method for measuring the amount of discharged droplets according to 11.   The weight of the droplet having a size larger than the size to be measured is determined by depositing a droplet having a size larger than the size to be measured on the predetermined medium a predetermined number of times. The weight is measured, and obtained by calculating based on the measured weight of the medium after the droplet ejection and the number of droplet ejection of a size larger than the size to be measured. Item 13. The method for measuring the amount of ejected droplets according to any one of Items 1 to 12.

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