JP2007112078A - Device/method for inspecting inkjet head nozzle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inspecting an inkjet head nozzle which can easily adjust a positional relationship between an inkjet head and a measuring apparatus in a detection region with a reduced number of inspection procedures, and also can inspect the assembling precision of the inkjet head, and an inspection device. <P>SOLUTION: This inkjet head nozzle inspection device comprises a transfer drive part which can move the inkjet head to be inspected in a direction where nozzles are aligned, an image processing part which processes an image of a liquid droplet formed in an imaging element and a control part which controls the transfer drive part and the image processing part. The inkjet head is inspected using the liquid droplets ejected from a plurality of the nozzles of the inkjet head, and a nozzle to eject the liquid droplet is previously assigned. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet head nozzle inspection device and an inspection method.

  As market demands for inkjet printers, there are demands for higher resolution, higher printing speeds, and lower prices. For this reason, an increase in the number of channels, an improvement in landing accuracy, a decrease in the amount of droplets, an increase in ejection speed, and a reduction in manufacturing cost are mentioned in the multi-nozzle.

  Conventionally, ink ejection inspection of an ink jet printer head has been performed using a medium printed on paper or the like. In the case of this method, there is a problem that the inspection work becomes complicated, and further, since a recording medium is necessary, the cost is generated and the manufacturing cost of the head itself is increased.

Therefore, a droplet inspection apparatus that does not use a recording medium has been developed. A droplet, which is the object to be measured, is placed between the light source of an optical system composed of one or a plurality of lenses that image a point light source and the image, and the surrounding light is blocked at the image formation position of the light source. By providing a mechanism and newly providing an optical system that forms an image of the liquid droplet to be measured, and by arranging an image sensor at the image formation position of the liquid droplet, A method that can accurately detect the state has been proposed. (For example, see Patent Document 1)
JP 2001-150659 A

  In order to measure the state of droplets emitted from all nozzles of the inkjet head, it is necessary to move the head to the detection area of the measuring instrument. Conventionally, it has been manually performed to adjust the positional relationship between the head and the detection area of the measuring instrument. For this reason, it takes time and labor for inspection.

  To provide an inspection method and an inspection apparatus for an inkjet head that can easily adjust the positional relationship between the detection area of the head and the measuring instrument in the inkjet head nozzle inspection, reduce the number of inspection steps, and at the same time inspect the assembly accuracy of the head. Objective.

The object of the present invention is achieved by the following configurations.
(1)
A droplet emitted from the inkjet head is placed between the light source of the optical system composed of one or a plurality of lenses that image the light source and the image, and the image of the droplet is formed on the image sensor. In an inkjet head nozzle inspection apparatus for inspecting an inkjet head,
A moving drive unit for moving the inkjet head for inspection in the direction in which the nozzles are arranged;
An image processing unit that performs image processing on the image of the liquid droplet formed on the image sensor;
A control unit that controls the movement drive unit and the image processing unit,
An inkjet head nozzle inspection apparatus, wherein an inkjet head is inspected using droplets emitted from a plurality of nozzles of the inkjet head, and nozzles for ejecting the droplets are designated in advance.
(2)
The inkjet head nozzle according to (1), wherein the control unit controls the movement driving unit to move the inkjet head based on data notified from the image processing unit. Inspection device.
(3)
The control unit is configured to determine whether the ejection of ink from the nozzles of the inkjet head is operating normally based on the data notified from the image processing unit (1) or The inkjet head nozzle inspection device according to (2).
(4)
A droplet emitted from the inkjet head is placed between the light source of the optical system composed of one or a plurality of lenses that image the light source and the image, and the image of the droplet is formed on the image sensor. In an inkjet head nozzle inspection method for inspecting an inkjet head,
A moving drive unit for moving the inkjet head for inspection in the direction in which the nozzles are arranged;
An image processing unit that performs image processing on the image of the liquid droplet formed on the image sensor;
A control unit that controls the movement drive unit and the image processing unit,
An inkjet head nozzle inspection method, wherein an inkjet head is inspected using droplets emitted from a plurality of nozzles of the inkjet head, and nozzles for ejecting the droplets are designated in advance.
(5)
(4) The inkjet head nozzle inspection method according to (4), wherein the control unit controls the movement driving unit to move the inkjet head based on data notified from the image processing unit.
(6)
The control unit determines whether ink ejection from the nozzles of the inkjet head is operating normally based on data notified from the image processing unit (4) or (5) The inkjet head nozzle inspection method as described in 2.

  A liquid droplet is ejected from a nozzle designated in advance, and an image of the liquid droplet is formed on the image sensor, whereby the positional deviation of the nozzle with respect to the head housing is determined. By moving the head to the movement drive unit based on the displacement amount, the positional relationship between the head and the detection area of the measuring instrument can be easily adjusted, and the nozzle inspection process can be shortened. As a result, the productivity of the inkjet head can be greatly improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram illustrating an example of an inkjet head nozzle inspection apparatus.

  In the figure, 10 is a light source, 11 is a lens for focusing light from the light source 10, and A and B are droplets. Reference numeral 12 denotes a slit arranged at a position where an image of the light source 10 is formed. The light that has passed through the slit 12 forms an image of a droplet on the CCD 6. In this way, the droplets A and B are arranged between the light source 10 and the image, and the optical system lens 11 that forms the image of the light source and the optical system that forms the image of the droplet are combined. Here, strobe light or laser pulse emission is used as the light source 10. Thereby, even a moving droplet can be detected in an accurate state.

  By using such an optical system, the droplets A and B are imaged on the CCD 6. As a result, images of droplets A and B can be obtained. Here, the reason why the slit 12 is disposed at the image forming point of the light source 10 is to block the bent light and allow only the linear light to pass through, thereby accurately detecting the image of the droplet. Here, the slit can be changed. According to this, the optimum aperture can be used according to the state of the droplet, and an accurate droplet image can be obtained.

  When the configuration as shown in FIG. 1 is used, the state of the liquid droplets emitted from the inkjet head can be accurately detected by arranging the liquid droplets between the light source and the image. That is, the shape and position of a plurality of droplets can be measured with high accuracy. In addition, measurement is possible with a wide field of view (the number of droplets that can be measured per time can be increased). As a result, the injection speed, the injection angle (landing position accuracy), the droplet amount, etc. can be measured with high accuracy and at high speed.

  In this case, it is possible to use a dummy ink having the same viscosity and the like that is not colored as a droplet to be measured, and to prevent contamination after the inspection, it is not necessary to clean or refill the ink. be able to.

  FIG. 2 is a schematic view of the inkjet head nozzle inspection apparatus according to the present invention. 1 and 2 are denoted by the same reference numerals.

  The head 13 emits droplets according to data and control signals from the head drive unit 15. The head 13 is mounted with its reference surface pressed against an abutting member of a carrier (not shown). The carrier moves in the direction of arrow X according to a control signal from the movement drive unit 14.

  The head drive unit 15 causes droplets to be ejected from the nozzles designated by the image data signal of the head based on the image data signal and the ejection timing signal from the control unit 8.

  The strobe drive unit 16 turns on or off the light source 10 based on an instruction from the control unit 8.

  The image processing unit 7 performs image processing on the droplet image formed on the CCD 6 at a high speed, and transmits the processed image to the control unit 8. The control unit displays the transmitted image on the display screen.

  The control unit 8 includes, for example, a PC (personal computer) or the like, and comprehensively controls the head driving unit 15, the movement driving unit 14, the strobe driving unit 16, and the image processing unit 7.

  FIG. 3 is a schematic diagram of the droplet image formed on the CCD 6 being processed by the image processing unit 7 and then transmitted to the control unit 8 and displayed on a display (not shown).

  The head 13 whose reference surface is pressed against the not-shown carrier abutting member 21 is moved to the initial position by the movement drive unit 14. The initial position is a position where the designated nozzle is imaged at the center of the CCD 6.

  Next, an image data signal and an emission timing signal for emitting only the nozzle specified on the left side from the nozzle designated by the control unit 8 are transmitted to the drive substrate 15. The head driving unit 15 ejects a droplet from a nozzle designated based on the ejection timing signal, the strobe driving unit 16 operates, and the CCD 6 forms an image of the droplet, and the formed image is an image processing unit. After being processed in 7, it is transferred to the control unit 8.

  The left side of FIG. 3 is a diagram showing the positional relationship between the head housing 131 and the nozzle plate 132. On the right side, the image of the droplet imaged on the CCD 6 is image-processed and then transferred and displayed on a display (not shown) of the control unit 8. A ′ and B ′ are images of droplets displayed on the display. For example, B ′ is an image of droplets emitted by the nozzles 1321 of the nozzle plate 132. A ′ is an image of a droplet emitted from the nozzle 1322.

  The operation of the ink jet injection inspection apparatus according to the present invention will be described with reference to the schematic diagrams of FIGS.

  FIG. 3A shows a state in which the head housing 131 and the nozzle plate 132 are assembled with high accuracy. B 'is on the center line of the display. The distance between A ′ and B ′ is equal to the product of the distance between the nozzles 1322 and 1321 and the enlargement magnification displayed on the optical system and the display.

  FIG. 3B shows a state in which the nozzle plate 132 is assembled to the right side with respect to the head housing 131. B 'is offset to the right from the center line of the display. The distance between A ′ and B ′ coincides with the product of the distance between the nozzles 1322 and 1321 and the magnification.

  FIG. 3C shows a state where the nozzle plate 132 is assembled while being biased to the left with respect to the head housing 131. B 'is offset to the left from the center line of the display. The distance between A ′ and B ′ coincides with the product of the distance between the nozzles 1322 and 1321 and the magnification.

  FIG. 3D shows a state where the nozzle plate 132 is assembled while being inclined with respect to the head housing 131. B 'is slightly shifted to the left from the center line of the display. The distance between A ′ and B ′ is shorter than the distance between the nozzles 1322 and 1321 and the product described above.

  From these, it is possible to measure the assembly accuracy of the head casing 131 and the nozzle plate 132 based on the distance D between the center line and B ′ and the information on the distance F between A ′ and B ′.

  4 and 5 are flowcharts showing the assembly accuracy of the head 13 and the flow of inspection of droplet ejection from the nozzle in the configuration of FIG. The inspection procedure will be described according to the flowchart.

  The inspection is started by bringing the head to be inspected 13 into contact with the abutting member 21 of the carrier.

  In step S1, the control unit 8 issues an initialization instruction to the movement drive unit 14, moves the carrier, and stops at the initial position.

  In step S <b> 2, the control unit 8 transmits an image data signal and an emission timing signal to the head driving unit 15. The head driving unit 15 emits light only from the nozzle (for example, the rightmost nozzle in FIG. 3) designated by the received image data signal and the adjacent nozzle. The control unit 8 repeatedly outputs the image data signal and the emission timing signal to the head driving unit 15. The head repeats emission.

  In step S <b> 3, the control unit 8 outputs to the strobe driving unit 16 strobe ON delayed by a predetermined time from the emission timing signal. The strobe drive unit emits strobe light in response to a strobe ON signal. The control unit 8 repeatedly outputs a strobe ON signal to the strobe driving unit 16.

  In step S <b> 4, the CCD 6 captures the image of the emitted droplet and outputs it to the image processing unit 7.

  In step S5, the image processing unit 7 performs image processing such as luminance, contrast, shading correction, size adjustment, and mirror image processing at high speed on the captured image data.

  In step S6, the image processing unit 7 sends the image data subjected to the image processing to the control unit.

  In step S7, a distance D between the right droplet in FIG. 2 and the center line of the CCD sensor is calculated.

  In step S8, the distance between the two droplets is calculated. Let F be the calculation result.

  In step S9, the preset predetermined value 1 is compared with the D value. If the D value is smaller than the predetermined value 1 (step S9: YES), the process proceeds to step S10. If the D value is greater than or equal to the predetermined value 1 (step S9: NO), the process proceeds to step S26. The predetermined value 1 means that the D value is larger than 0 when the head housing 131 and the nozzle plate 132 are assembled while being displaced. This is an allowable value for the D value. That is, it is a value that is regarded as defective when assembled at a predetermined value of 1 or more.

  In step S10, the preset predetermined value 2 is compared with the F value. If the F value is larger than the predetermined value 2 (step S10: YES), the process proceeds to step S11. If the F value is smaller than or equal to the predetermined value 2 (step S10: NO), the process proceeds to step S26. The predetermined value 2 means that the F value becomes small when the head casing 131 and the nozzle plate 132 are assembled while being tilted. This is an allowable value for the F value. That is, it is a value that is regarded as defective when assembled with a deviation of a predetermined value 2 or more.

  In step S11, the control unit 8 converts the D value into the amount of head movement.

  In step S <b> 12, the control unit 8 sends the converted value to the movement drive unit 14.

  In step S13, the movement drive unit 14 moves the head based on the received converted value. After movement, B 'is displayed on the center line of the display.

  In step S <b> 14, the control unit 8 changes the image data signal transmitted in step S <b> 2 to all nozzle emission and transmits it to the head drive unit 15.

  Steps S15 to S17 perform the same operations as steps S4 to S6 described above, and thus description thereof is omitted.

  In step S18, the number of droplet images captured by the size of the CCD 6 is limited. The number of images taken into the CCD 6 at a time is determined. The control unit 8 checks whether there is a droplet not displayed on the display in the image data sent from the image processing unit 7. If there is no dropout (step S8: YES), the process proceeds to step S19. If a dropout is missing (step S18: NO), the process proceeds to step S27.

  In step S19, it is confirmed whether all nozzles have been checked. If it has been completed (step S19: YES), the process proceeds to step S22. If it has not been completed (step S19: NO), the process proceeds to step S20.

  In step S <b> 20, the movement set value is sent to the movement driving unit 14.

  Here, the movement set value will be described with reference to FIG. The moving set value means the distance to move the head from the plurality of droplets displayed on the display shown in FIG. 6A until the next plurality of droplets are displayed. That is, when 11 droplets are displayed as shown in FIG. 6A, when the head 13 is moved a distance based on the movement set value, an image of the droplets emitted from the next 11 nozzles is formed on the CCD 6. Displayed on the display.

  If the third droplet from the right is missing as shown in FIG. 6B, it means that the number of head movements from the initial position and the information on the third droplet from the right indicate what is from the right end of the nozzle row. It is determined whether the emission from the second nozzle has not been performed.

Returning to FIG.
In step S <b> 21, the movement driving unit 14 moves the head 13 by an amount based on the movement setting value sent from the control unit 8. That is, the head is moved by a distance of 11 nozzles.

  In step S <b> 22, the control unit 8 stores in the storage unit (not shown) the number of nozzles from which droplets have dropped out from the right end of the nozzle row.

  In step S <b> 23, the control unit 8 stops the transfer of the image data signal and stops the transmission to the head driving unit 15. In response to these instructions, the head 13 stops emission.

  In step S <b> 24, the control unit 8 outputs strobe OFF to the strobe driving unit 16. The strobe driving unit 16 stops the strobe light emission.

  In step S25, the control unit 8 checks the droplet dropout information stored in the storage unit (not shown) in step S22. If there is no dropout (step S25: YES), the process proceeds to step S26. If there is a dropout (step S25: NO), the process proceeds to step S27.

  In step S26, since the head 13 is a non-defective product, non-defective processing is performed.

  In step S27, since the head 13 is a defective nozzle product, for example, a defective nozzle number tag or the like is attached to the head to perform defective product processing.

  Steps S28 and 29 perform the same operations as steps S23 and S24, and thus description thereof is omitted.

  In step S30, since the head accuracy is poor, for example, a tag with a head precision failure is attached to the head, and defective products are processed.

  In addition, the detailed configuration and detailed operation of each component constituting the inkjet nozzle inspection apparatus can be changed as appropriate without departing from the spirit of the present invention.

It is a schematic diagram which shows an example of an inkjet head test | inspection apparatus. It is the schematic diagram which looked down at the inkjet head inspection apparatus which concerns on this invention. It is a schematic diagram which shows the structure which displays the droplet image imaged on CCD on a display. 3 is a flowchart 1 showing the assembly accuracy of the head 13 and the flow of nozzle check inspection in the configuration of FIG. 2. FIG. 3 is a flowchart 2 showing a flow of inspection of head 13 assembly accuracy and nozzle check in the configuration of FIG. 2. It is a schematic diagram explaining a movement setting value.

Explanation of symbols

6 CCD
7 Image processing unit 8 Control unit 10 Light source (strobe)
DESCRIPTION OF SYMBOLS 11 Lens 12 Slit 13 Head 14 Movement drive part 15 Head drive part 16 Strobe drive part 131 Head housing 132 Nozzle plate

Claims (6)

A droplet emitted from the inkjet head is placed between the light source of the optical system composed of one or a plurality of lenses that image the light source and the image, and the image of the droplet is formed on the image sensor. In an inkjet head nozzle inspection apparatus for inspecting an inkjet head,
A moving drive unit for moving the inkjet head for inspection in the direction in which the nozzles are arranged;
An image processing unit that performs image processing on the image of the liquid droplet formed on the image sensor;
A control unit that controls the movement drive unit and the image processing unit,
An inkjet head nozzle inspection apparatus, wherein an inkjet head is inspected using droplets emitted from a plurality of nozzles of the inkjet head, and nozzles for ejecting the droplets are designated in advance. The inkjet head nozzle according to claim 1, wherein the control unit controls the movement driving unit to move the inkjet head based on data notified from the image processing unit. Inspection device. 2. The control unit according to claim 1, wherein the control unit determines whether or not the ejection of ink from the nozzles of the inkjet head is operating normally based on data notified from the image processing unit. The inkjet head nozzle inspection device according to 2. A droplet emitted from the inkjet head is placed between the light source of the optical system composed of one or a plurality of lenses that image the light source and the image, and the image of the droplet is formed on the image sensor. In an inkjet head nozzle inspection method for inspecting an inkjet head,
A moving drive unit for moving the inkjet head for inspection in the direction in which the nozzles are arranged;
An image processing unit that performs image processing on the image of the liquid droplet formed on the image sensor;
A control unit that controls the movement drive unit and the image processing unit,
An inkjet head nozzle inspection method, wherein an inkjet head is inspected using droplets emitted from a plurality of nozzles of the inkjet head, and nozzles for ejecting the droplets are designated in advance. 5. The inkjet head nozzle inspection method according to claim 4, wherein the control unit controls the movement drive unit to move the inkjet head based on data notified from the image processing unit. 6. The control unit according to claim 4, wherein the control unit determines whether or not ejection of ink from the nozzles of the inkjet head is operating normally based on data notified from the image processing unit. Inkjet head nozzle inspection method.

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