JPH1044399A - Method and system for inspecting ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a system for inspecting an ink jet head in which an ink hole can be detected easily regardless of adhesion of ink to the nozzle forming plane. SOLUTION: Ink in the nozzle hole of an ink jet head 1 is oscillated by imparting an oscillation to a pipe 2 for feeding the ink to the ink jet head 1 under stationary state. Enlarged image of the nozzle forming plane 1b of the ink jet head 1 is then picked up by means of a camera 11 and variation in the image of the nozzle forming plane due to variation in the state of ink in the nozzle hole is detected thus locating the nozzle hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for inspecting an ink jet head for printing by ejecting ink to a recording medium through nozzle holes.

[0002]

2. Description of the Related Art Conventionally, an ink jet head provided in an ink jet printer has been inspected for a discharge state of a nozzle for discharging ink droplets onto printing paper.

In such an inspection, first, in order to search for a nozzle hole in a nozzle forming surface of an ink jet head, an image of the nozzle forming surface is enlarged and photographed by photographing means such as a CCD camera. An image is projected on a monitor screen to check a nozzle hole.

[0004]

However, in addition to the fact that the nozzle holes on the nozzle forming surface are very small and difficult to confirm, in addition to the fact that ink adheres to the nozzle forming surface, the It is difficult to distinguish between the attached portion and the nozzle hole filled with ink, and the nozzle hole cannot be confirmed with high accuracy.

The present invention has been made in view of the above circumstances, and provides an ink jet head inspection method and apparatus which can easily detect a nozzle hole regardless of whether or not ink adheres to a nozzle forming surface. With the goal.

[0006]

The method of the present invention presupposes a method of inspecting an ink jet head which prints by ejecting ink to a recording medium through a nozzle hole. The nozzle of the ink jet head is kept stationary while the ink jet head is stationary. Vibration is applied to the ink in the holes, the nozzle forming surface of the inkjet head is enlarged and photographed and observed, and a change in the image of the nozzle forming surface due to a change in the ink state in the nozzle holes is detected. , The position of the nozzle hole. In other words, when vibration is applied to the ink in the nozzle hole of the inkjet head, the ink state in the nozzle hole changes, and the image on the nozzle forming surface changes due to the change. Is specified.

In order to realize the above method, the apparatus of the present invention is an inspection apparatus for an ink jet head for printing by ejecting ink to a recording medium through a nozzle hole, wherein the ink jet head is stationary while the ink jet head is stationary. Vibration applying means for applying vibration to the ink in the nozzle holes of the ink jet head, photographing means for enlarging and observing the nozzle forming surface of the ink jet head, and a nozzle for receiving an image photographed by the photographing means. A nozzle hole detecting means for detecting a change in the image of the nozzle forming surface due to a change in the ink state in the hole and specifying the position of the nozzle; According to this device, the ink in the nozzle hole of the ink jet head is vibrated by the vibration applying means, whereby the state of the ink in the nozzle hole changes, and the ink is enlarged by the photographing means due to the change. The image of the nozzle forming surface being photographed and observed changes.
Based on the change in the image, the position of the nozzle hole is specified by the nozzle hole detection unit. The vibration applying unit applies vibration to an ink supply pipe that supplies ink to the inkjet head, or sets the inkjet head to By using a head drive control unit that drives under a drive condition in which ink is not ejected, it is possible to easily apply vibration to the ink in the nozzle holes while the inkjet head is stationary.

Further, a monitor means for projecting an image of the nozzle forming surface photographed by the photographing means on a monitor screen, and a picture projected on the monitor screen based on the position of the nozzle hole detected by the nozzle hole detecting means. Positioning means for positioning the nozzle holes.
Therefore, based on the positions of the nozzle holes detected by the nozzle hole detecting means, the positioning of the nozzle holes projected on the monitor screen by the monitoring means is easily and accurately performed by the positioning means.

Since the positioning means moves the ink jet head relative to the photographing means, the positioning of the nozzle holes can be performed accurately, and the ejection of ink droplets can be accurately observed. it can.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an inspection apparatus for an ink jet head 1 for printing by ejecting ink to a recording medium (not shown) through nozzle holes 1a, 1a,. (Not shown) Nozzle hole 1 in nozzle forming surface 1b of inkjet head 1 mounted on
a, 1a,... are magnified from the front direction (Y-axis direction), and a first camera 11 as photographing means for photographing and observing, and ink droplets ejected from the nozzle holes 1a, 1a,. The camera includes a second camera 12 for photographing the discharge state of a track or the like from the horizontal direction (X-axis direction) and a third camera 13 for photographing the ejection state from the vertical direction (Z-axis direction). The camera 11, 1
2 and 13 are color or monochrome CCDs, respectively.
It consists of a camera and a microscope.

In addition, the ink jet head 1 includes:
An ink supply pipe 2 for supplying ink to the inkjet head 1 is connected. As shown in FIG. 2, vibrations are mechanically applied to the ink in the nozzle holes 1a, 1a,... Of the ink jet head 1 while the ink jet head 1 is stationary. The vibration applying means 3 is linked. The vibration applying means 3 is constituted by a so-called vibrator or the like, and applies vibration only to the ink supply pipe 2 that supplies ink to the inkjet head 1. By vibrating the ink supply pipe 2, the ink supply pipe 2 is vibrated. Are transmitted to the ink in the nozzle holes 1a, 1a,... Through the ink in the nozzle holes 1a, 1a,.
・ ・ The ink inside will be vibrated.

Further, the first camera 11 is linked to an image processing device 14 constituting a nozzle hole detecting means. The image processing device 14 receives the image captured by the first camera 11, compares the image before the vibration is applied by the vibration applying unit 3 with the image after the vibration is applied, and compares the image after the vibration is applied with the nozzle holes 1 a, 1 a,. .. Are configured to detect a change in the image of the nozzle forming surface 1b due to a change in the state of the ink therein, and to specify the positions of the nozzle holes 1a, 1a,.

The first camera 11 has the first camera
Inkjet head 1 photographed by camera 11
And a monitor means 15 for displaying an image of the nozzle forming surface 1b on the monitor screen.
Based on the position of the nozzle hole 1a detected by the image processing device 14, the nozzle hole 1a projected on the monitor screen by the positioning means 16 linked to
Is to be aligned. The alignment by the alignment means 16 is performed by moving an inspection stage (not shown) on which the inkjet head 1 is mounted. When the alignment is performed, for example, a monitor is provided by a cross line generator (not shown). The cross line projected on the monitor screen of the means 15 is used as a reference.

On the other hand, the second and third cameras 12 and 13
Although not specifically shown, the image processing apparatus is linked to an image processing device that digitally processes the image of the ink droplets captured by the cameras 12 and 13, and the image processing device is a CRT monitor that displays the image-processed image. And a computer that performs arithmetic analysis on the shape, size, and track of ink droplets based on signals output from the image processing device.

Therefore, in a state where the ink jet head 1 is stationary without being driven, the ink vibration applying means 3
When the ink supply pipe 2 is vibrated by the nozzles, the nozzle holes 1a, 1a,.
Vibration is applied to the ink inside the nozzles, and the ink inside the nozzle holes 1a, 1a,... On the nozzle forming surface 1b also vibrates.

That is, as shown in FIG. 3, the nozzle holes 1a,
Since the ink oscillates back and forth in 1a,..., The ink surface changes irregularly only in the nozzle holes 1a, 1a,. Observing the nozzle hole 1
a, 1a,... can be easily confirmed. Therefore, even if the ink P adheres to the nozzle forming surface 1b, the nozzle holes 1a, 1a,... Can be easily detected. In this case, as described above, since it is not necessary to drive the ink jet head 1, the ink does not scatter around.

Subsequently, a method of inspecting the ink jet head 1 will be specifically described.

First, a keyboard of a computer (not shown) is operated to select a drive waveform for driving the head, and then an inspection stage (not shown) on which the inkjet head 1 is mounted is inspected. Move to the position
The inkjet head 1 is aligned.

Then, a camera is selected and various parameters are set. For example, parameters to be set include a voltage OFF time (a time during which an ink ejection pulse rises), a stage position (setting of a position where the first nozzle in the first row is located at the center of the three-dimensional space), and an alignment nozzle (1
When the row / first nozzle is defective, set the nozzle number for alignment), the zoom magnification (change the zoom value of the color CCD), the light emission phase time of the shooting strobe (the strobe emits light from the falling edge of the ink ejection pulse) Time setting), vertical pitch (setting of nozzle vertical pitch (DPI)) and horizontal pitch (setting of nozzle row pitch (μm))
And so on.

Next, a reference cross line is projected on the monitor screen of the monitor means 15, and the first camera 1
By setting the magnification in microscope 1 to about 3 times,
Focus adjustment is performed by enlarging the nozzle forming surface 1b of the inkjet head 1 and moving the inkjet head 1 in the Y-axis direction.

Thereafter, the enlarged image of the nozzle hole 1a to be inspected is searched for while performing photographing observation while enlarging the nozzle forming surface 1b. That is, by applying vibration to the ink supply pipe 2 by the vibration applying means 3, as described above, the image of the nozzle forming surface 1b caused by the change in the ink state in the nozzle holes 1a, 1a,. The change is detected, and the positions of the nozzle holes 1a, 1a,.

Then, positioning is performed so that the enlarged image of the nozzle hole 1a to be inspected matches the reference cross line.

After the positioning is completed, ink droplets are ejected from the nozzle holes by the ejection pulse having the set driving waveform, and the ejection state of the ink droplets is photographed and recorded by the second and third cameras 12 and 13. And inspect.

In the above embodiment, the ink supply pipe 2 is mechanically vibrated as the vibration applying means. However, the frequency of the vibration does not necessarily have to be a constant frequency. However, simply by manually vibrating the ink supply pipe 2, the nozzle holes can be similarly detected.

The vibration applying means may be a head drive control means for driving the ink jet head 1 to such an extent that ink is not ejected. For example, the ink is ejected by applying a drive voltage of about 50% of the drive voltage applied to the head when printing, or by applying a drive pulse having a changed pulse width so that the ink is not ejected. Instead, the ink state in the nozzle hole may be varied. This makes it possible to easily configure the vibration applying means without installing a special vibration applying mechanism.

[0027]

The present invention is embodied in the form described above and has the following effects.

While the ink jet head is stationary, a vibration is applied to the ink in the nozzle hole of the ink jet head, and the nozzle forming surface of the ink jet head is enlarged and observed for photographing. Since the change of the image of the nozzle forming surface due to the change is detected and the position of the nozzle hole is specified, even if the ink is attached to the nozzle forming surface, the nozzle hole can be easily detected. it can.

A vibration applying means for applying vibration to the ink in the nozzle holes of the ink jet head while the ink jet head is stationary; a photographing means for enlarging and observing a nozzle forming surface of the ink jet head; A nozzle hole detecting unit that receives a video image captured by the imaging unit, detects a change in the image of the nozzle forming surface caused by a change in the ink state in the nozzle hole, and specifies the position of the nozzle. With a simple structure, even if ink adheres to the nozzle forming surface,
The nozzle holes can be easily detected.

Since the vibration applying means applies vibration to the ink supply pipe for supplying ink to the ink jet head, the vibration can be easily applied. In addition, if the head drive control means drives the inkjet head under a driving condition in which ink is not ejected, vibration can be easily applied without providing a special vibration applying mechanism.

Further, a monitor means for projecting an image of the nozzle forming surface photographed by the photographing means on a monitor screen, and a picture projected on the monitor screen based on the position of the nozzle hole detected by the nozzle hole detecting means. Since the apparatus is provided with the positioning means for performing the positioning of the nozzle hole, the nozzle hole can be easily detected by comparing the normal state and the state with the vibration.

The positioning means moves the photographing means relative to the ink jet head.
Detection of nozzle holes is simple.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an inkjet head inspection apparatus according to the present invention.

FIG. 2 is an explanatory view of a vibration applying means according to the present invention.

FIG. 3 is an explanatory diagram of an inspection of an inkjet head according to the present invention.

FIG. 4 is an explanatory diagram of the inspection of the inkjet head according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet head 1a Nozzle hole 1b Nozzle formation surface 2 Ink supply pipe 3 Vibration applying means 11 First camera 12 Second camera 13 Third camera

Claims (6)

[Claims] 1. A method for inspecting an ink-jet head for printing by ejecting ink through a nozzle hole to a recording medium, wherein vibration is applied to ink in the nozzle hole of the ink-jet head while the ink-jet head is stationary. And performing a photographing observation by enlarging a nozzle forming surface of the inkjet head, detecting a change in an image of the nozzle forming surface caused by a change in the ink state in the nozzle hole, and specifying a position of the nozzle hole. A method for inspecting an ink jet head, comprising: 2. An ink jet head inspection apparatus for performing printing by ejecting ink to a recording medium through nozzle holes, wherein vibration is applied to ink in the nozzle holes of the ink jet head while the ink jet head is stationary. A vibration imparting unit, a photographing unit for photographing and observing the nozzle forming surface of the inkjet head by enlarging the nozzle forming surface, and receiving the image photographed by the photographing unit, receiving the image photographed by the photographing unit. An inspection apparatus for an ink jet head, comprising: a nozzle hole detection unit that detects a change in an image on a surface and specifies a nozzle position. 3. The ink jet head inspection apparatus according to claim 2, wherein said vibration applying means applies vibration to an ink supply pipe for supplying ink to said ink jet head. 4. The inspection apparatus for an ink jet head according to claim 2, wherein said vibration applying means is a head drive control means for driving said ink jet head under a driving condition in which ink is not ejected. 5. A monitor means for projecting an image of the nozzle forming surface photographed by the photographing means on a monitor screen; and a monitor screen based on the position of the nozzle hole detected by the nozzle hole detection means. The inspection apparatus for an ink jet head according to any one of claims 2 to 4, further comprising a positioning unit that performs positioning of the projected nozzle hole. 6. The inspection apparatus for an ink jet head according to claim 5, wherein the positioning means moves the ink jet head relative to the photographing means.