JP2001150696A - Device for examining ink jet injection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for examining ink jet injection which can exactly detect the condition of liquid droplets discharged from an ink head. SOLUTION: Liquid droplets to be tested are arranged between the light source of an optical system comprising one or more lenses for imaging by the light source and an image, a nozzle is somewhat inclined to the injection direction, parallel light is emitted from the upper or lower part of the nozzle to illuminate the droplets, and the transmitted light is made to form the image of the droplets by an image pick-up element.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet ejection inspection apparatus, and more particularly, to an ink-jet ejection inspection apparatus capable of accurately detecting droplets, and in particular, accurately measuring the landing accuracy of a plurality of droplets in the main scanning direction. The present invention relates to an inkjet injection inspection device.

[0002] Market demands for ink jet printers include higher resolution, higher printing speed, and lower price. Therefore, the number of channels, the accuracy of impact, the amount of liquid droplets, the ejection speed, and the manufacturing cost are reduced in the multi-nozzle.

[0003]

2. Description of the Related Art Conventionally, an ink ejection test 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 is complicated, and further, since a recording medium is required, the cost is generated, and the manufacturing cost of the head itself is increased.

For this reason, a droplet inspection apparatus which does not use a recording medium has been developed (for example, Japanese Patent Application Laid-Open No. H11-22717).
No. 2). FIG. 2 is a diagram showing a configuration example of a conventional device.
In the figure, 1 is a strobe light source, 2 is a strobe light source 1
Is a reflecting mirror arranged so as to surround. Reference numeral 3 denotes a secondary light source that receives strobe light, for example, a white scatterer or a diffusion plate is used. The light from the secondary light source 3 is droplets A and B
And the transmitted light is imaged on the CCD 6 via the lens 4. Reference numeral 7 denotes a camera moving mechanism for moving the CCD.

[0005] In the device thus constructed, d is the distance between the droplets A and B, and the field of view is represented by 2d. is the divergence angle of the light beam, where L is the distance from the secondary light source 3 to the lens 4, and D is the aperture of the lens 4, and is represented by θ = D / L. The incident angle φ of the light beam is represented by φ = d / L. Then, the droplet image is formed on the CCD 6.

[0006]

It is a well-known technique to detect the position and velocity of a droplet with a flash light source such as a strobe. For example, in the invention described in Japanese Patent Application Laid-Open No. 5-149767, there is no description of illumination, and
In the invention described in Japanese Patent No. 72, the strobe lighting is measured a plurality of times, and there is no description of the lighting method. Further, the apparatus shown in FIG. 2 can measure only the landing accuracy in the sub-scanning direction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an ink jet ejection inspection apparatus capable of accurately detecting the state of droplets ejected from an ink head. .

[0008]

According to a first aspect of the present invention, an object to be measured is provided between an image and a light source of an optical system including one or a plurality of lenses for forming an image of the light source. Arrange a droplet, tilt the nozzle slightly in the ejection direction, irradiate parallel light from the top or bottom of the nozzle, illuminate multiple droplets, capture the transmitted light and capture the image of the droplet with a telecentric lens An image is formed on an element.

With this configuration, by evaluating the linearity of the droplet row, it is possible to measure the landing accuracy of a plurality of droplets in the main scanning direction. (2) The invention according to claim 2 is characterized in that a flash light source is used as the light source.

With this configuration, it is possible to accurately detect a moving droplet. (3) The invention according to claim 3 is characterized in that the optical system is used in combination with an optical system used for measuring the landing accuracy of droplets in the sub-scanning direction.

With this configuration, the configuration is simplified by using the optical system and the sub-operation direction optical system together. (4) The invention described in claim 4 is characterized in that the head is moved up and down and the detection optical system corrects the distance from the head.

With this configuration, it is possible to measure the behavior of the droplet in the vicinity of the designated landing position. (5) The invention described in claim 5 is characterized in that, at the time of the above measurement, an emission signal is sent only to a nozzle in a measurement visual field and a plurality of nozzles before and after.

With this configuration, it is possible to prevent droplets from adhering to the optical system and to ensure the accuracy of ejection measurement. (6) The sixth aspect of the present invention is characterized in that the linearity of a row of a plurality of measured droplet images is inspected.

With this configuration, it is possible to inspect the linearity of the measured droplet by checking whether the rows of the measured droplet images are arranged in a straight line. (7) The invention described in claim 7 is characterized in that the parallelism between the head reference position and the optical system is measured.

With this configuration, it is possible to determine whether the mechanical arrangement is correctly set. (8) The invention according to claim 8 is characterized in that in the case of a multistage nozzle, the parallelism of the rows of the droplet images ejected from each nozzle row is measured.

With this configuration, it is possible to determine whether or not a plurality of rows of liquid droplets are arranged in parallel. (9) The ninth aspect of the present invention is characterized in that the position is adjusted when the head is fixed to the printer using the head reference line and the measurement result of the parallelism.

With this configuration, the position can be adjusted when the head is fixed to the printer. (10) The tenth aspect of the present invention is characterized in that the required accuracy of the droplet image and the visual field measured at a time or the required light amount are adjusted by changing the aperture of the illumination system or the light receiving system.

With this configuration, it is possible to adjust the required accuracy of the droplet image, the visual field measured at a time, and the required light amount. (11) The invention according to claim 11 is characterized in that a bright portion at the center of the droplet is masked before the center of gravity measurement.

According to this structure, a preferable droplet image can be obtained by masking the center of the droplet, and the droplet can be accurately recognized. (12) The invention according to claim 12 is characterized in that the outer diameter of the droplet is measured from the concentration value of the outer diameter portion of the droplet output from the image sensor.

With this configuration, the contrast of the outer diameter portion of the liquid droplet is improved, so that the outer diameter of the liquid droplet can be measured with a resolution within one pixel from the density value of the outer diameter portion of the liquid droplet. (13) The invention according to claim 13 is characterized in that a colorless and transparent dummy ink is used in place of the ink.

With this configuration, the use of the dummy ink prevents contamination after the inspection, so that there is no need to wash or refill the ink.

(14) According to a fourteenth aspect of the present invention, when the measurement visual field is moved, an image picked up in a state where there is no droplet is stored in advance, and the liquid is taken from an image picked up in a state where there is a droplet. It is characterized in that an image taken in a state without a drop is subtracted.

With this configuration, it is possible to perform shading correction on the obtained droplet image.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention. The same components as those in FIG. 2 are denoted by the same reference numerals. In the figure, 1 is a light source, 10 is a lens that focuses light from the light source 1, and 11 is the lens 10
Is a slit (aperture) provided in the vicinity of the image forming point. As the light source 1, for example, pulse light of a strobe or a laser is used. Reference numeral 12 denotes a lens for converting the light from the aperture 11 into a parallel light beam, 13 a mirror for reflecting the light from the lens 12, and 14 a mirror for reflecting the light from the mirror 13. Reference numeral 15 denotes a telecentric lens which receives light from the mirror 14 and forms an image of the droplet 18 on the CCD 6. Reference numeral 16 denotes a slit (aperture) that blocks a part of the light from the telecentric lens 15.

Reference numeral 17 denotes, for example, a head having nozzles mounted in a matrix. The head 17 is mounted with the nozzle slightly inclined in the injection direction. Reference numeral 18 denotes a droplet ejected from the head 17. Here, a case where a plurality of droplets in three rows are attached is shown. The light from the light source 1 is illuminated by the mirror 13 as parallel light from above or below the nozzle with respect to the droplet 18. The operation of the device configured as described above will be described below.

Light emitted from a flash light source (for example, a strobe) 1 is condensed by a lens 10 and
1 and enters the lens 12. The lens 12 converts incident light into parallel light. This parallel light is reflected by the subsequent mirror 13 and enters another mirror 14.

In this case, since the head 17 is mounted as shown in the figure, the droplets 18 emitted from the head 17 do not overlap, and are emitted with a slight displacement as shown in the figure. . As a result, the droplets 18 illuminated by the mirror 13 do not overlap. After the droplet image is reflected by the second mirror 14, it is incident on the telecentric lens 15 and forms an image on the CCD 6. The figure shows a case where a droplet image is displayed or formed on an image display unit or transfer paper.

As described above, according to the present embodiment, it is possible to accurately detect the state of the droplets arranged in a line.
In the present embodiment, a flash light source is used as a light source. By using a flash light source, it is possible to accurately detect a moving droplet.

According to the present embodiment, the optical system shown in FIG. 1 can be used together with the sub-scanning direction optical system. Thereby, the configuration can be simplified. In this embodiment, the head can be moved in the vertical direction, and the detection optical system can also correct the position of the head. According to this, it is possible to measure the behavior of the droplet in the vicinity of the designated landing position.

Further, in the present embodiment, when measuring a droplet, it is possible to send an ejection signal only to a nozzle in the measurement visual field and a plurality of nozzles before and after. According to this, it is possible to prevent the droplet from adhering to the optical system and to ensure the accuracy of the ejection measurement.

In this embodiment, the linearity of a plurality of rows of the measured droplet images is inspected. If the nozzle is normal, an image composed of a plurality of droplets becomes linear, so that the measured linearity of the droplet can be inspected.

In this embodiment, the parallelism between the head reference position and the optical system can be measured. According to this, it is possible to determine whether the mechanical position of the head is set correctly for the optical system.

In this embodiment, when a multi-stage nozzle is used as a nozzle, the parallelism of the droplet images ejected from each nozzle row can be measured. As shown in FIG. 1, for example, it is possible to determine whether the droplets of the nozzles composed of three rows are arranged in parallel, and it is possible to grasp the performance of the nozzles.

Further, according to this embodiment, the parallelism between the head reference line and the droplet image can be measured. According to this, the position can be adjusted when the printer head is fixed.

Further, according to the present embodiment, the aperture (slit) of the illumination system or the light receiving system can be changed. According to this, it is possible to adjust the required accuracy of the droplet image and the visual field measured at a time or the required light amount.

Further, according to the present embodiment, a bright portion at the center of the droplet can be masked before the center of gravity measurement. According to this, by performing image processing for masking the center of the droplet, a preferable droplet image can be obtained, and the droplet can be accurately recognized.

Further, according to the present embodiment, the outer diameter of the droplet can be measured from the density value of the outer diameter portion of the droplet output from the image sensor. According to this, since the contrast of the outer diameter portion of the droplet is improved, the outer diameter of the droplet can be measured with the maximum resolution (for example, within one pixel) from the density value of the outer diameter portion of the droplet.

Further, according to the present embodiment, a colorless and transparent dummy ink can be used instead of the ink when measuring the droplet. According to this, the use of the dummy ink prevents contamination after the inspection, so that there is no need to wash or refill the ink. Further, according to the present invention, an image captured in a state where there is no liquid droplet is stored in advance, and an image captured in a state where there is no liquid droplet is subtracted from an image captured in a state where there is a liquid droplet. Shading correction of the drop image can be performed.

[0039]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first aspect of the present invention, the nozzle is slightly inclined in the emission direction, parallel light is irradiated from the upper or lower part of the nozzle, a plurality of droplets are illuminated, and the transmitted light is transmitted by the telecentric lens. By forming the image of the droplet on the image sensor, the linearity of the droplet row is evaluated, and thus the landing accuracy of the plurality of droplets in the main scanning direction can be measured.

(2) According to the second aspect of the invention, by using a flash light source as the light source, it is possible to accurately detect a moving droplet. (3) According to the third aspect of the present invention, the configuration is simplified by using the optical system together with the optical system used for measuring the landing accuracy of the droplet in the sub-scanning direction.

(4) According to the fourth aspect of the present invention, the head is moved in the vertical direction, and the detection optical system corrects the distance from the head, so that the behavior of the droplet near the designated landing position is improved. Can be measured.

(5) According to the fifth aspect of the present invention, at the time of the above measurement, the ejection signals are sent only to the nozzles within the measurement visual field and a plurality of front and rear nozzles, thereby preventing droplets from adhering to the optical system. In addition, the accuracy of the injection measurement can be ensured.

(6) According to the present invention, the linearity of the plurality of measured droplet images is inspected to determine whether or not the measured droplet images are arranged in a straight line. The linearity of the dropped droplet can be inspected.

(7) According to the seventh aspect of the present invention, it is possible to determine whether the mechanical arrangement is correctly set by measuring the parallelism between the head reference position and the optical system.

(8) According to the eighth aspect of the invention, in the case of a multistage nozzle, by measuring the parallelism of the rows of the droplet images ejected from each nozzle row, a plurality of rows of droplets can be parallelized. It can be determined whether they are lined up.

(9) According to the ninth aspect of the invention, the head is fixed to the printer by adjusting the position when fixing the head to the printer using the head reference line and the measurement result of the parallelism. In this case, the position can be adjusted.

(10) According to the tenth aspect of the present invention,
By adjusting the required accuracy of the droplet image and the visual field to be measured at one time by changing the aperture of the illumination system or the light receiving system, or by adjusting the required light amount, the required accuracy of the droplet image and the visual field to be measured at one time are adjusted. And the required light quantity can be adjusted.

(11) According to the eleventh aspect,
By masking the bright portion at the center of the droplet before measuring the center of gravity, the center of the droplet can be masked to obtain a preferable droplet image, and the droplet can be accurately recognized.

(12) According to the twelfth aspect of the present invention,
From the concentration value of the outer diameter of the droplet output from the image sensor,
By measuring the outer diameter of the droplet, the contrast of the outer diameter portion of the droplet is improved. Therefore, the outer diameter of the droplet can be measured with a resolution within one pixel from the density value of the outer diameter portion of the droplet.

(13) According to the thirteenth aspect,
By using a colorless and transparent dummy ink instead of the ink, the use of the dummy ink prevents contamination after inspection, so that there is no need to wash or refill the ink.

(14) According to the fourteenth aspect,
When the measurement field of view is moved, shading is performed by preliminarily storing an image captured without a droplet and subtracting the image captured without the droplet from an image captured with a droplet. By performing the correction, a more accurate image can be obtained.

As described above, according to the present invention, it is possible to provide an ink jet ejection inspection apparatus capable of accurately detecting the state of droplets ejected from an ink head.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration example of a conventional device.

[Explanation of symbols]

 Reference Signs List 1 light source 6 CCD 10 lens 11 slit 12 lens 13 mirror 14 mirror 15 telecentric lens 16 slit 17 head

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazunori Yamamoto 1 Sakura-cho, Hino-shi, Tokyo F-term in Konica Corporation (reference) 2C056 EB08 EB29 EB36 EB40 EE17 KD10 2F065 AA26 AA32 AA52 BB15 BB29 CC00 DD03 FF42 FF43 GG04 GG12 HH05 HH13 JJ03 JJ09 JJ26 KK03 LL12 LL28 LL30 LL59 MM24 PP02 QQ21 QQ32 QQ37

Claims (14)

[Claims] A liquid droplet to be measured is arranged between an image and a light source of an optical system including one or a plurality of lenses for forming an image of a light source, and a nozzle is slightly inclined in an ejection direction. An ink jet ejection inspection apparatus, which irradiates parallel light from above or below a nozzle, illuminates a plurality of droplets, and forms an image of the droplet on an image sensor by a telecentric lens with transmitted light. 2. An ink-jet injection inspection apparatus according to claim 1, wherein a flash light source is used as said light source. 3. The ink jet ejection inspection apparatus according to claim 1, wherein the optical system is used in combination with an optical system used for measuring the landing accuracy of a droplet in the sub-scanning direction. 4. The ink-jet injection inspection apparatus according to claim 1, wherein the head is moved in a vertical direction, and the detection optical system corrects the distance from the head. 5. The ink-jet injection inspection apparatus according to claim 1, wherein, at the time of the measurement, an injection signal is sent only to the nozzles in the measurement visual field and a number of nozzles before and after. 6. The inkjet ejection inspection apparatus according to claim 1, wherein the linearity of the plurality of measured droplet image rows is inspected. 7. The ink jet injection inspection apparatus according to claim 1, wherein the parallelism between the reference position of the head and the optical system is measured. 8. The ink jet injection inspection apparatus according to claim 1, wherein in the case of a multistage nozzle, the parallelism of a row of droplet images ejected from each nozzle row is measured. 9. The ink jet injection inspection apparatus according to claim 1, wherein the position adjustment at the time of fixing the head to the printer is performed using the head reference line and the measurement result of the parallelism. 10. The ink-jet injection according to claim 1, wherein the required precision of the droplet image and the visual field measured at a time or the required light quantity are adjusted by changing the aperture of the illumination system or the light receiving system. Inspection equipment. 11. The ink-jet ejection inspection apparatus according to claim 1, wherein a bright portion at the center of the droplet is masked before measuring the center of gravity. 12. The ink jet ejection inspection apparatus according to claim 1, wherein the outer diameter of the droplet is recognized with a resolution within one pixel from the density value of the outer diameter portion of the droplet output from the imaging device. 13. The apparatus according to claim 1, wherein a colorless and transparent dummy ink is used instead of the ink. 14. When the measurement visual field is moved, an image captured in a state without a droplet is stored in advance, and an image captured in a state without a droplet is converted from an image captured in a state with a droplet. The inkjet ejection inspection apparatus according to claim 1, wherein the subtraction is performed.