JP2003083714A - Apparatus and method for measuring droplet landing position - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for measuring a droplet landing position wherein the repelling, the spread and the blur of an ink in the landing of an ink droplet onto a recording medium are disregarded and the landing position of the ink droplet is measured surely. SOLUTION: A laser beam emitted from a laser light emitting part 4 is changed into sheet light 5 by a lens unit 9, the ink droplet is discharged to the center of the point of intersection of two orthogonal beams of sheet light 5, the reflected light or the transmitted refracted light of the ink droplet with reference to the beams of sheet light 5 and a nozzle opening 2 are imaged by an imaging device 8, an imaged image is image-processed, the coordinates of the nozzle opening 2 and the coordinates of the ink droplet are calculated, the coordinates of the nozzle opening 2 are compared with the coordinates of the ink droplet, and the landing position of the ink droplet is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a droplet landing position measuring device and a droplet landing position measuring method, and more particularly to ejecting ink from a nozzle opening of an ink jet head to land the ink on a recording medium and print an image. The present invention relates to a droplet landing position measuring device and a droplet landing position measuring method for evaluating the landing position of an ink droplet.

[0002]

2. Description of the Related Art Heretofore, various methods have been proposed for measuring the landing position of ink droplets ejected from a nozzle opening of an ink jet head of the above ink jet printer.

In the method disclosed in Japanese Patent Laid-Open No. 2000-62158, at least one ink droplet is ejected from an ejection port of an ink jet head, and a recording medium such as paper is located apart from the ejection port surface. The ink droplets that have landed and landed on the ejection port and the recording medium are imaged and image-processed by an image processing camera arranged below the recording medium to measure the respective coordinates, and the ejected ink droplets and the ejected ink droplets are ejected. It was a method of measuring the landing position from the coordinates of the exit.

Further, the method described in Japanese Patent Laid-Open No. 7-329302 is a droplet landing position inspection method in which ink is ejected from nozzles of an ink jet head to print an image on an actual printing paper. This is an inspection method in which a line inspection pattern is printed on a printing paper which is a medium, ink is ejected onto the inspection pattern, and the landing position shift of the ink droplet is visually determined.

[0005]

However, JP-A-2000-62158 and JP-A-7-3 of the above-mentioned conventional examples.
Japanese Patent No. 29302 has the following problems.

In the method of observing or measuring the landing position of the ink droplet by actually landing the ink droplet on the recording medium, the ink is repelled or spread at the time of landing, and bleeding causes the ink ejection port With respect to the position, there is a problem that it is not possible to accurately measure which portion the ink droplet actually landed on. Furthermore, the relationship between the position coordinates of the nozzle opening and the position where the recording medium is placed is
It is difficult to perform accurate measurement in the three-dimensional direction, and there arises a problem that the landing position of the ink droplet on the nozzle opening cannot be accurately measured. Further, due to the scattering of small droplets called satellites that are ejected as the ink droplets are ejected, the main ink droplets and satellites overlap and land on the recording medium, making it difficult to accurately measure the landing position.

An object of the present invention is to provide a droplet landing position measuring device which realizes reliable measurement of the landing position of ink droplets by ignoring ink repelling, spreading and bleeding when ink droplets land on a recording medium. And a droplet landing position measuring method.

[0008]

According to a first aspect of the present invention, the ink in an ink jet printer for printing an image by ejecting ink droplets from a nozzle opening of an ink jet head and landing them on a recording medium. In a droplet landing position measuring device for evaluating landing positions of droplets, the ink droplets are ejected in a direction intersecting with a light emitting means for emitting sheet light and sheet light emitted from the light emitting means. At this time, an image pickup means for picking up reflected light or transmitted refracted light of the ink droplet with respect to the sheet-like light, and a landing position measurement for measuring the landing position of the ink droplet based on the image picked up by the image pickup means A droplet landing position measuring device is provided.

In the above droplet landing position measuring device, the image pickup means images the reflected light or the transmitted refracted light of the ink droplet, and also picks up the image of the nozzle opening, and the landing position measurement means is the image pickup means. Based on the image captured by
Calculate the coordinates of the nozzle opening and the coordinates of the ink droplets,
The calculated coordinates of the nozzle openings and the coordinates of the ink droplets may be compared to measure the landing position of the ink droplets.

In the above droplet landing position measuring device, the light emitting means emits two orthogonal sheet-like lights, and the ink droplets are directed toward the center of the intersection of these sheet-like lights. May be ejected perpendicularly to the light.

In the above-mentioned droplet landing position measuring device, the image pickup means outputs the reflected light or the transmitted refracted light of the ink droplets to be imaged, with the unit for injecting the two orthogonal sheet-shaped lights. A unit for enlarging at a predetermined magnification may be provided.

The droplet landing position measuring apparatus may include an image processing means for performing image processing on the image picked up by the image pickup means.

According to a second aspect of the present invention, the landing position evaluation of the ink droplet in an ink jet printer that prints an image by ejecting the ink droplet from the nozzle opening of the ink jet head and landing it on the recording medium. In the droplet landing position measuring method, the ink droplets are ejected in a direction intersecting the sheet-like light, and reflected light or transmitted refracted light of the ink droplet with respect to the sheet-like light is imaged, There is provided a droplet landing position measuring method characterized by measuring the landing position of the ink droplet based on a captured image.

In the above-mentioned droplet landing position measuring method, the reflected light or the transmitted refracted light of the ink droplet is imaged, the nozzle opening is imaged, and the coordinates of the nozzle opening and the image are taken based on the taken image. The landing position of the ink droplet may be measured by calculating the coordinates of the ink droplet and comparing the calculated coordinates of the nozzle opening with the coordinates of the ink droplet.

In the above-described droplet landing position measuring method, the sheet-shaped light is composed of two orthogonal sheet-shaped lights, and the ink is ejected from the ink jet head toward the center of the intersection of these sheet-shaped lights. Ink droplets may be ejected perpendicularly to the sheet of light.

In the above-mentioned droplet landing position measuring method, the unit for injecting the two orthogonal sheet-like lights and the reflected or transmitted refracted light of the ink droplet to be imaged are magnified by a predetermined magnification. An image pickup unit including a unit may image the reflected light or the transmitted refracted light of the ink droplet and also image the nozzle opening.

In the droplet landing position measuring method described above, image processing may be performed on the captured image to calculate the coordinates of the nozzle openings and the coordinates of the ink droplets.

In the above droplet landing position measuring method, the ink jet droplets may be ejected from the ink jet head in a direction intersecting with the sheet-like light by positioning the ink jet head by the positioning means. .

Further, the droplet landing position measuring device of the present invention is
Referring to FIGS. 1 and 2, the ink liquid in an inkjet printer that prints an image by ejecting ink droplets from a nozzle opening (2) of an inkjet head (1) and landing them on a recording medium. In a droplet landing position measuring device for evaluating the landing position of a droplet, a light emitting means (4) for emitting light, and a light changing means (9) for converting the light emitted by the light emitting means into sheet-like light. When the ink droplets are ejected in a direction intersecting the sheet-shaped light changed by the light-changing means, the reflected light or the transmitted refracted light of the ink droplets with respect to the sheet-shaped light is imaged. And an image pickup means (8) for picking up an image of the nozzle opening,
Based on the image picked up by the image pickup means, the coordinate calculation means for calculating the coordinates of the nozzle openings and the coordinates of the ink droplets, and the coordinates of the nozzle openings and the coordinates of the ink droplets calculated by the coordinate calculation means. And a landing position measuring means for measuring the landing position of the ink droplet.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] Next, a first embodiment of the present invention will be described in detail with reference to the drawings.

(1) Description of Configuration FIG. 1 is an explanatory view showing the principle of measurement of the landing position of ink droplets ejected from an inkjet head of an inkjet printer according to the present invention. In FIG. 1, 1 is an inkjet head having nozzles, 2 is a nozzle opening for ejecting ink droplets (hereinafter abbreviated as droplets), 4 is a laser emitting section for emitting laser light, and 7 is an imaging device (CCD camera).
Is an image pickup incident optical unit equipped in the.

The direction of ejection of the liquid droplet 3 ejected from the nozzle opening 2 is a direction orthogonal to the sheet light (sheet-shaped laser light) 5 emitted from the laser emitting portion 4 and laid out at a separated position. An image pickup device (CCD camera) having reflected light (or transmitted refracted light) 6 generated when the droplet 3 passes through the sheet light 5 and having an image pickup incident optical unit 7.
The image is picked up (see FIG. 2), and the coordinates of the droplet 3 are obtained by image processing. Further, the position of the nozzle opening 2 is also imaged by the imaging incidence optical unit 7 (observation system) of the imaging device (CCD camera), and the coordinates of the nozzle opening 2 are obtained by image processing.

That is, the principle of the ink droplet landing position measurement in the present invention is to find the landing position of the ink droplet by comparing the coordinates of the nozzle opening 2 of the ink jet head 1 with the coordinates of the droplet 3 in the above procedure. That is.

FIG. 2 is a conceptual diagram showing an example of the configuration of the droplet landing position measuring device (prototype) of the first embodiment of the present invention. 2, 8 is an imaging device (CCD camera), 9 is a lens unit, 10 is an X stage for moving the inkjet head 1 in the X direction (horizontal direction), and 11 is for moving the inkjet head 1 in the Y direction (horizontal direction). Let Y
A stage, 12 is a Z stage for moving the inkjet head 1 in the Z direction (vertical direction), and 13 is an X stage 1.
Tilt mechanism for moving 0 in the vertical direction, 1
4 is a laser displacement meter, 15 is a θ stage (rotating mechanism) for rotating the X stage 10 in a horizontal plane, and 18 is an optical axis of the observation system.

Inkjet head 1 having nozzles
Can eject droplets in the vertical direction in the figure. The inkjet head 1 includes an X stage 10 and a Y stage 1.
1. The Z stage 12 can operate three-dimensionally.
In this case, the positional resolution of the X stage 10, the Y stage 11, and the Z stage 12 is, for example, 0.1 μm.
Further, the inkjet head 1 can be positioned with a precision of, for example, 0.1 μm in the rotational direction and the parallelism of the height by the rotation operation of the θ stage (rotation mechanism) 15 and the vertical movement of the tilt (tilt) mechanism 13. Is.

The method for positioning the ink jet head 1 is as follows.
Is imaged, and each axis is moved to a predetermined origin position on the monitor by manual operation of each axis. Finally, the origin on the monitor and the center point of the nozzle opening 2 are set to 0 by an origin alignment mechanism by image processing. Align with an accuracy of 1 μm or less. As for the parallelism in the height direction, the laser displacement meter 14 having an accuracy of 0.1 μm or less measures the distance between the lower surface of the nozzle opening 2 and the laser displacement meter 14 at three points, and the distance between the three points is displayed on the monitor. Display and show parallelism by manual operation. By the above operation, the position of the nozzle port 2 is changed to XYZ.
-Θ-Positioning is performed at a height of 0.1 μm or less.

When the nozzle opening 2 is positioned, the nozzle opening 2 is irradiated with halogen light obliquely from below, and the point-like reflected light is incident on the imaging device 8 from the nozzle opening 2. The nozzle mouth 2 is photographed. After that, the nozzle port 2 is moved upward in the Z direction, and then ink is ejected.

In the vertical direction of the ink jet head 1,
Sheet light 5 with a width of 4 mm and a thickness of 10 μm
Is laid out, and the position is adjusted at the time of assembly so that the center of the intersection of the sheet light 5 and the position of the origin on the monitor match. The laser light emitted from the laser emitting section 4 has good compatibility with the image pickup device (CCD camera) 8,
Since the wavelength is short, Y with a wavelength of 532 nm is also highly accurate.
A green laser with AG double harmonic was used. The laser light is split into two directions by a fiber cable, split into two sheet lights 5 by the lens unit 9, and the path of the sheet lights 5 is set so that the split two sheet lights 5 are orthogonal to each other. Changing.

A droplet of light is ejected toward the center of the intersection of the sheet light 5, and reflected light generated when passing through the sheet light 5 is imaged by an image pickup device (CCD camera) 8. In the image pickup device (CCD camera) 8, two orthogonal light beams can be made incident by the image pickup incident optical unit 7 having four mirrors and two 20 × magnification microscopes. In this case, the image pickup device (CCD camera) 8 is arranged, for example, at a position obliquely downward 45 degrees with respect to the reflected light (or the transmitted refracted light).

That is, the droplet landing position measuring device comprises a laser emitting section 4 for emitting a laser beam, a fiber cable (dispersing means) for splitting the laser beam in two directions, and two orthogonal sheet lights for the laser beam. When a droplet is ejected in a direction intersecting with a pair of lens units 9 that change to 5 and two orthogonal sheet lights 5, the reflected light or the transmitted refracted light of the droplet with respect to the sheet light 5 is imaged. In addition, the imaging device (CCD camera) for imaging the nozzle opening 2 and the imaging device (C
Nozzle port 2 based on the image taken by the CD camera)
Coordinates calculating means for calculating the coordinates of the droplet 3 and the coordinates of the droplet 3, and a landing position measuring means for measuring the landing position of the droplet 3 by comparing the coordinates of the nozzle opening 2 and the coordinates of the droplet 3 calculated by the coordinates calculating means. And is equipped with.

(2) Description of Operation Next, the operation of the first embodiment of the present invention will be described with reference to FIGS.
Will be described in detail with reference to.

FIG. 3 is a view showing an image picked up by the image pickup device (CCD camera) 8 of the landing position measuring apparatus shown in FIG. The upper left white dot is the image of the nozzle opening taken from the left side, the upper right white dot is the image of the nozzle opening taken from the right side, and the lower left white point is the image of the droplet taken from the left side. The lower right white dot is an image of the liquid droplet taken from the right side. The image of the nozzle opening is taken before the image of the liquid droplet is taken, and these images are included in the same photograph by image processing. That is, after irradiating the nozzle opening with halogen light obliquely from below to capture an image of the nozzle, the nozzle opening is moved upward in the Z direction. Then, a droplet is ejected from the nozzle opening, and the ejected droplet is imaged. In this case, the image of the nozzle opening and the image of the droplet are formed at substantially the same height,
Different heights are used when combining images. The coordinate calculation means is
The difference between the coordinates of the upper left white point and the lower left white point in the horizontal axis direction and the difference between the upper right white point and the lower right coordinate of the horizontal axis are calculated. This 2
A two-dimensional deviation (deviation on the XY plane) of the droplet coordinates with respect to the nozzle opening coordinates when the nozzle opening is viewed in the vertical direction (Z-axis direction) can be calculated from the two differences. The example of FIG. 3 is an example in which the coordinates of the nozzle and the coordinates of the droplet are well aligned.

FIG. 4 is a diagram showing how the origin of the image picked up by the image pickup device (CCD camera) 8 is obtained by image processing software, that is, 2 orthogonal to the droplet 3.
It is a figure which shows that the droplet origin 22 is calculated | required by the optical axis 21 for observation of a book. FIG. 4 shows that the image of the nozzle port 2 and the image of the droplet are captured as two images in the orthogonal directions. The origin 22 of the captured image is obtained by image processing software.

In the droplet landing position measurement experiment of the first embodiment, the center of the nozzle port 2 of the ink jet head 1 is set as the origin (0, 0), and the arbitrary number of ejections (1, 50, 10).
The results of determining the droplet landing position coordinates (μm) of 0, 500, 1000, 5000) are shown in FIG. The ink is black, the laser is a green laser with 500 mW output of YAG double harmonic of 532 nm wavelength, the reflected light of the liquid droplet is imaged by the imaging device (CCD camera) 8, and the coordinates are measured by the image processing software for measurement. I asked.

FIG. 5 shows the nozzle port 22 and the nozzle port origin 20.
And a droplet image 21 obtained from an image of the reflected light of the droplet.
It is a figure which shows and the droplet origin 23. The deviation of the origins from each other causes variations in the landing positions.

As described above, in the measurement of the landing position of the liquid droplets ejected from the ink jet head 1 of the ink jet printer, the nozzle opening 2 of the ink jet head 1 is positioned with a high accuracy of 0.1 μm or less, and the ink at the time of landing is ejected. By repellency, spread, and bleeding,
It was shown that it is possible to solve the conventional problem that it is not possible to accurately measure which portion actually hits the discharge port position.

That is, according to the present invention, the problem of ink repelling, spreading, and bleeding at the time of landing of the droplet from the ink jet head 1 onto the recording medium, which has been a problem in the prior art, does not occur, and the droplet is prevented. The landing position can be measured with high accuracy. Furthermore, the scattering of small droplets called satellites that are ejected as the droplets are ejected causes the main droplets and satellites to overlap and land on the recording medium, making it difficult to accurately measure the landing position. It can be resolved. If the landing position of the droplet becomes clear,
Development of the optimum ejection port (ejection port unit part) in an inkjet printer can be carried out quickly and reliably, and the effect brought by the development of the optimal ejection port (ejection port unit part) is the improvement of printing position accuracy, It is possible to contribute to high definition drawing.

[Second Embodiment] Next, a second embodiment of the present invention will be described in detail with reference to the drawings.

(1) Description of Configuration The principle of the droplet landing position measurement of the second embodiment of the present invention (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) are the same as those of the first embodiment. is there.

(2) Description of Operation Next, the operation of the second embodiment of the present invention will be described with reference to FIGS.
Will be described in detail with reference to.

An experiment was conducted by changing the laser to a 500 mW He-Ne laser in the landing position measuring device prototyped this time in FIG. The He-Ne laser has a stable output waveform, can stabilize the luminance, and can perform a reliable experiment. In addition, since it is the cheapest and most distributed laser, it has a great advantage. Of course, availability is good, and there is no problem in obtaining a laser. He-
The Ne laser becomes sheet light having a width of 4 mm and a thickness of 10 μm by the lens unit 9. In this experiment, the reflected light when the droplet passes through the sheet light was captured. Black was used as the ink (black ink absorbs a large amount of light and is difficult to pass through due to its characteristics. Therefore, it will catch reflected light).

FIG. 7 is a diagram showing an image of the nozzle openings 2 of the ink jet head 1 and an image of liquid droplets, which are taken by the image pickup device (CCD camera) 8. Similar to the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image with the image processing software.

[Third Embodiment] Next, a third embodiment of the present invention will be described in detail with reference to the drawings.

(1) Description of Configuration The principle of the droplet landing position measurement (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) of the third embodiment of the present invention are the same as those of the first embodiment. is there.

(2) Description of Operation Next, the operation of the third embodiment of the present invention will be described with reference to FIGS.
Will be described in detail with reference to.

In the landing position measuring device prototyped this time in FIG. 2, the laser was a 500 mW He—Ne laser, and an experiment was conducted with a sheet light having a width of 4 mm and a thickness of 10 μm.
As the ink, magenta of color ink was used. Magenta has a characteristic of transmitting laser light with almost no reflection in terms of transmittance. That is, the image to be imaged in this experiment is not an image of reflected light but an image of transmitted refracted light.

FIG. 8 is a diagram showing an image of the nozzle openings 2 of the ink jet head 1 and an image of liquid droplets, which are picked up by the image pickup device (CCD camera) 8. Similar to the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image with the image processing software.

[Fourth Embodiment] Next, a fourth embodiment of the present invention will be described in detail with reference to the drawings.

(1) Description of Configuration The principle of the droplet landing position measurement (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) of the fourth embodiment of the present invention are the same as those of the first embodiment. is there.

(2) Description of Operation Next, the operation of the fourth embodiment of the present invention will be described with reference to FIGS.
Will be described in detail with reference to.

In the landing position measuring device prototyped this time in FIG. 2, the laser was set to 500 mW Ar laser (argon laser), and the experiment was conducted by using sheet light having a width of 4 mm and a thickness of 10 μm. The Ar laser is characterized by high output and brightness. As the ink, the magenta color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light with almost no reflection in terms of transmittance. That is, the image to be imaged in this experiment is not an image of reflected light but an image of transmitted refracted light.

FIG. 9 is a diagram showing an image of the nozzle openings 2 of the ink jet head 1 and an image of liquid droplets, which are picked up by the image pickup device (CCD camera) 8. Similar to the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image with the image processing software.

[Fifth Embodiment] Next, a fifth embodiment of the present invention will be described in detail with reference to the drawings.

(1) Description of Configuration The principle of the droplet landing position measurement of the fifth embodiment of the present invention (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) are the same as those of the first embodiment. is there.

(2) Description of Operation Next, the operation of the fifth embodiment of the present invention will be described with reference to FIGS.
This will be described in detail with reference to 0.

In the landing position measuring device prototyped this time in FIG. 2, the laser is a semiconductor laser of 5 mW and the width is 4 m.
The experiment was conducted by using a sheet light having a thickness of m and a thickness of 10 μm. The semiconductor laser is characterized by its small size, space saving, and easy handling. The ink has a third
As in the embodiment, magenta of color ink was used. Magenta has a characteristic of transmitting laser light with almost no reflection in terms of transmittance. That is, the image to be imaged in this experiment is not an image of reflected light but an image of transmitted refracted light.

FIG. 10 shows an image pickup device (CCD camera) 8
FIG. 3 is a diagram showing an image of a nozzle opening 2 of the inkjet head 1 and an image of a liquid droplet, which are captured by FIG. Similar to the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image with the image processing software.

[Sixth Embodiment] A sixth embodiment of the present invention will now be described in detail with reference to the drawings.

(1) Description of Configuration The principle of the droplet landing position measurement (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) of the sixth embodiment of the present invention are the same as those of the first embodiment. is there.

(2) Description of Operation Next, the operation of the sixth embodiment of the present invention will be described with reference to FIGS.
This will be described in detail with reference to FIG.

In the above-mentioned trial landing position measuring device of FIG. 2, the light source is a halogen lamp of 100 W and the width is 4
The experiment was carried out with sheet light having a thickness of 10 mm and a thickness of 10 mm. The halogen lamp produces a wide range of light without the spectral interference of the laser. The halogen lamp is also a safe light source in terms of handling. As the ink, as in the third embodiment, magenta of color ink was used. Magenta has a characteristic of transmitting laser light with almost no reflection in terms of transmittance. That is, the image to be imaged in this experiment is not an image of reflected light but an image of transmitted refracted light.

FIG. 11 shows an image pickup device (CCD camera) 8
FIG. 3 is a diagram showing an image of a nozzle opening 2 of the inkjet head 1 and an image of a liquid droplet, which are captured by FIG. Similar to the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image with the image processing software.

[Seventh Embodiment] Next, a seventh embodiment of the present invention will be described in detail with reference to the drawings.

(1) Description of Configuration The principle of the droplet landing position measurement (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) of the seventh embodiment of the present invention are the same as those of the first embodiment. is there.

(2) Description of Operation Next, the operation of the seventh embodiment of the present invention will be described with reference to FIGS.
This will be described in detail with reference to 2.

In the landing position measuring device prototyped this time in FIG. 2, the laser was a 500 mW He—Ne laser, and an experiment was conducted with a sheet light having a width of 4 mm and a thickness of 10 μm. As the ink, as in the third embodiment, magenta of color ink was used. Magenta has a characteristic of transmitting laser light with almost no reflection in terms of transmittance. That is, the image to be imaged in this experiment is not an image of reflected light but an image of transmitted refracted light.

FIG. 12 is a diagram showing an image of the nozzle port 2 of the ink jet head 1 and an image of a liquid droplet, which are taken by a silver halide camera. Similar to the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image with the image processing software.

[Eighth Embodiment] An eighth embodiment of the present invention will now be described in detail with reference to the drawings.

(1) Description of Configuration The principle of the droplet landing position measurement (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) of the eighth embodiment of the present invention are the same as those of the first embodiment. is there.

(2) Description of Operation Next, the operation of the eighth embodiment of the present invention will be described with reference to FIGS.
This will be described in detail with reference to FIG.

In the landing position measuring apparatus prototyped this time in FIG. 2, the laser was a 500 mW He—Ne laser, and an experiment was conducted with a sheet light having a width of 4 mm and a thickness of 10 μm. As the ink, the magenta color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light with almost no reflection in terms of transmittance. That is, the image to be imaged in this experiment is not an image of reflected light but an image of transmitted refracted light.

FIG. 13 is a diagram showing an image of the nozzle port 2 of the ink jet head 1 and an image of a liquid droplet, which are taken by an electronic camera incorporating a C-MOS sensor. Similar to the first embodiment, it has been shown that the landing position can be measured by performing image processing of the captured image with the image processing software.

[Ninth Embodiment] Next, a ninth embodiment of the present invention will be described in detail with reference to the drawings.

(1) Description of Configuration The principle of the droplet landing position measurement (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) of the ninth embodiment of the present invention are the same as those of the first embodiment. is there.

(2) Description of Operation Next, the operation of the ninth embodiment of the present invention will be described with reference to FIGS.
This will be described in detail with reference to FIG.

In the landing position measuring device prototyped this time in FIG. 2, the laser was a 500 mW He—Ne laser, and an experiment was conducted with a sheet light having a width of 4 mm and a thickness of 10 μm. As the ink, the magenta color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light with almost no reflection in terms of transmittance. That is, the image to be imaged in this experiment is not an image of reflected light but an image of transmitted refracted light.

FIG. 14 is a diagram showing an image of the nozzle openings 2 of the ink jet head 1 and an image of liquid droplets, which are taken by the one-dimensional line sensor. Similar to the first embodiment, it has been shown that the landing position can be measured by performing image processing of the captured image with the image processing software.

[0078]

As described above, according to the present invention,
Ink droplets are ejected in the direction intersecting the sheet-like light, and the reflected light or transmitted refracted light of the ink droplets with respect to the sheet-like light is imaged, and the nozzle opening of the inkjet head is imaged, and the captured image is displayed. By performing image processing, the coordinates of the nozzle opening and the coordinates of the ink droplet are calculated, the coordinates of the nozzle opening and the coordinates of the ink droplet are compared, and the landing position of the ink droplet is measured. With high accuracy and by actually landing ink droplets on the recording medium, the problem of the method of observing and measuring the landing position, which is a problem with ink repellency, spread, and bleeding at the time of landing, is ignored. It is possible to measure the landing position of the droplet. Further, as a ripple effect, problems and countermeasures for nozzle development are clarified, and it is possible to expect realization of a high-quality inkjet printer in a timely manner.

That is, according to the present invention, there is no problem of ink repelling, spreading, and bleeding at the time of landing of a droplet from an ink jet head onto a recording medium, which has been a problem in the prior art. The position can be measured with high accuracy. Furthermore, the scattering of small droplets called satellites that are ejected as the droplets are ejected causes the main droplets and satellites to overlap and land on the recording medium, making it difficult to accurately measure the landing position. It can be resolved. If the landing position of the droplet becomes clear,
Development of the optimum ejection port (ejection port unit part) in an inkjet printer can be carried out quickly and reliably, and the effect brought by the development of the optimal ejection port (ejection port unit part) is the improvement of printing position accuracy, It is possible to contribute to high definition drawing.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the principle of landing position measurement of ink droplets according to first to ninth embodiments of the present invention.

FIG. 2 is a conceptual diagram showing a prototype of an ink droplet landing position measuring device according to first to ninth embodiments of the present invention.

FIG. 3 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing how the origin of an imaged image is obtained by image processing software according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing variation of droplets according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing a result of obtaining droplet landing position coordinates of an arbitrary ejection stroke number according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to the second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to the third embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to a fourth embodiment of the present invention.

FIG. 10 is an explanatory diagram illustrating a captured nozzle opening image and a droplet image according to the fifth embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to the sixth embodiment of the present invention.

FIG. 12 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to a seventh embodiment of the present invention.

FIG. 13 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to the eighth embodiment of the present invention.

FIG. 14 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to a ninth embodiment of the present invention.

[Explanation of symbols]

1 inkjet head 2 nozzle mouth 3 droplets 4 Laser emission part 5 sheet light 6 Reflected light or transmitted refracted light 7 Imaging incident optical unit 8 Imaging device 9 lens unit 10 X stage 11 Y stage 12 Z stage 13 Tilt mechanism 14 Laser displacement meter 15 θ stage

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Claims (11)

[Claims] 1. A droplet landing position measuring device for evaluating landing positions of the ink droplets in an inkjet printer that prints an image by ejecting ink droplets from a nozzle opening of an inkjet head and landing them on a recording medium. A sheet emitting light and a reflection of the ink droplet with respect to the sheet light when the ink droplet is ejected in a direction intersecting the sheet light emitted from the light emitting means. Imaging means for imaging light or transmitted refracted light;
A droplet landing position measuring device comprising: a landing position measuring unit that measures the landing position of the ink droplet based on the image captured by the image capturing unit. 2. The image pickup means picks up reflected light or transmitted refracted light of ink droplets and picks up an image of the nozzle opening, and the landing position measuring means, based on the image picked up by the image pickup means, The droplet according to claim 1, wherein coordinates of a nozzle opening and coordinates of the ink droplet are calculated, and the calculated coordinates of the nozzle opening and coordinates of the ink droplet are compared to measure a landing position of the ink droplet. Landing position measuring device. 3. The light emitting means emits two orthogonal sheet-like lights, and ejects the ink droplets perpendicularly to the sheet-like lights toward the center of the intersection of these sheet-like lights. The droplet landing position measuring device according to claim 1 or 2, characterized in that. 4. The image pickup means includes a unit for injecting the two orthogonal sheet-shaped lights and a unit for enlarging reflected light or transmitted refracted light of the ink droplet to be imaged at a predetermined magnification. The droplet landing position measuring device according to claim 3, further comprising: 5. The droplet landing position measuring device according to claim 1, further comprising image processing means for performing image processing on the image taken by the imaging means. 6. A droplet landing position measuring method for evaluating landing positions of the ink droplets in an inkjet printer that prints an image by ejecting ink droplets from a nozzle opening of an inkjet head and landing them on a recording medium. The ink droplets are ejected in a direction intersecting with the sheet-shaped light, and reflected light or transmitted refracted light of the ink droplets with respect to the sheet-shaped light is imaged, and the ink liquid is A droplet landing position measuring method, characterized in that a landing position of a droplet is measured. 7. The reflected light or the transmitted refracted light of the ink droplet is imaged, the nozzle opening is imaged, and the coordinates of the nozzle opening and the coordinates of the ink droplet are calculated based on the taken image. 7. The droplet landing position measuring method according to claim 6, wherein the landing position of the ink droplet is measured by comparing the calculated coordinates of the nozzle opening with the coordinates of the ink droplet. 8. The sheet-shaped light is composed of two orthogonal sheet-shaped lights, and directs the ink droplets from the inkjet head to the sheet-shaped light toward the center of the intersection of the sheet-shaped lights. The droplet landing position measuring method according to claim 6 or 7, wherein the droplets are ejected perpendicularly to the light. 9. An image pickup unit comprising: a unit for injecting the two orthogonal sheet-shaped lights; and a unit for enlarging reflected light or transmitted refracted light of the ink droplet to be imaged at a predetermined magnification. 9. The droplet landing position measurement method according to claim 8, wherein the reflected light or the transmitted refracted light of the ink droplet is imaged and the nozzle opening is imaged. 10. The liquid according to claim 7, wherein image processing is performed on the captured image to calculate the coordinates of the nozzle openings and the coordinates of the ink droplets. Drop landing position measurement method. 11. The ink droplets are ejected from the inkjet head in a direction intersecting with the sheet-shaped light by positioning the inkjet head by a positioning means.
The method for measuring the droplet landing position according to any one of 1.