JPH1069857A - Shadow mask inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To examine an overall mask face for defects by scanning the mask behind the frame of a shadow mask on which an incident optical path has already been formed. SOLUTION: A line sensor camera 5 is disposed so that it can photograph a mask face 2 as sharply as possible with a linear viewing field stretching over the entire width of the mask face, and that an incident optical path scans the entire mask face 2 in X direction via a mirror 3. A control means 22 controls a linear servo motor 20 so that an optical path incident on the line sensor camera 5 from the mask face 2 holds constant an optical path length between the mask face 2 and the line sensor camera 5, on the centerline of the mask face in the cross direction Y. This constitution enables the entire mask face 2 to be photographed and examined for defects.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a shadow mask inspection apparatus which images a mask surface of a formed shadow mask such as a CRT and inspects the mask surface for defects.

[0002]

2. Description of the Related Art Shadow masks such as CRTs have come to be inspected for defects such as clogging or abnormal hole diameter on the mask surface by an automatic inspection device. In particular, the importance of defect inspection of the mask surface 2 of the formed shadow mask 1 in which the frame 4 is formed around the mask surface 2 as shown in FIG.

A conventional shadow mask inspection apparatus is shown in FIGS.
As shown in FIG. 6, two line sensor cameras 5, 5
A transport stage 31 on which the formed shadow mask 1 is placed and transported at a constant speed in the longitudinal direction X of the mask surface 2, a backlight 32 for irradiating transmitted light from below to an imaging unit on the mask surface 2, and image processing means 33.

[0004] The two line sensor cameras 5 and 5 are fixed above the transport stage 31 with the light receiving part facing downward.
Shaped shadow mask 1 conveyed on the conveyance stage 31
Is adjusted so as to capture an image of the mask surface 2 with a line-shaped visual field over the entire width (Y direction) of the mask surface 2. At this time, the image processing means 33 processes the images obtained from the transfer position of the transfer stage 31 and the image pickup signals of the two line sensor cameras 5 and 5, and performs a defect inspection of the mask surface 2.

[0005]

However, in the above-described conventional shadow mask inspection apparatus, as shown in FIG.
Since the line sensor cameras 5 and 5 are fixed and the movement of the formed shadow mask 1 is linear, the length of the mask surface 2 hidden in the frame 4 of the formed shadow mask 1 as viewed from the line sensor cameras 5 and 5 There is a problem that the imaging of both ends 6, 6 in the direction X cannot be performed. Further, although the mask surface 2 of the formed shadow mask 1 is a part of a spherical surface, the line sensor camera 5 is fixed, so that the optical path length between the shadow mask 1 and the line sensor camera 5 depends on the imaging site of the mask surface 2. In particular, there is a problem that the focus is easily blurred at both ends 6, 6 in the longitudinal direction X of the mask surface 2.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a shadow mask inspection apparatus capable of inspecting a defect on the entire mask surface without being affected by a frame of a formed shadow mask.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a shadow mask inspection apparatus for inspecting a mask surface of a molded shadow mask for defects, which is disposed at a position facing the mask surface. A mirror, and turning means for turning the mirror so that an optical path of light incident on the line sensor camera from the mask surface via the mirror scans the entire mask surface.

According to the present invention, the mirror is rotated so that the optical path of light incident on the line sensor camera from the mask surface also scans the mask surface located behind the frame of the shaped shadow mask. The entire surface can be imaged.

In the present invention, a driving means for driving the line sensor camera in the optical axis direction in synchronization with the rotation of the mirror so as to keep the optical path length between the mask surface and the line sensor camera constant is provided. Then, the optical path length between the entire mask surface and the line sensor camera is kept substantially constant by the driving means, so that a sharp image can be taken over the entire mask surface.

In the present invention, if the driving means is configured to include a cam that rotates together with the mirror and a coupling means that is guided by the cam surface and drives the line sensor camera in the optical axis direction, the mirror can be rotated. The line sensor camera can be driven by a single powering means, and the cost of parts can be reduced.

In the present invention, the driving means includes a sensor for reading the rotational position of the mirror, and a camera moving means for driving the line sensor camera in the optical axis direction by a distance corresponding to the rotational position read by the sensor. In this configuration, there is no need for a connecting means for mechanically connecting the rotating means and the driving means, so that assembly and adjustment can be facilitated.

In the present invention, if the rotation means is configured to rotate the mirror so that the optical path on the mask surface is scanned at a constant speed, it is possible to capture an image with substantially the same sensitivity over the entire mask surface. Yes, it is.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

In the first embodiment of the present invention, as shown in FIGS. 1 and 2, a line sensor camera 5 for capturing an image of a mask surface 2 of a molded shadow mask 1 with a line-shaped visual field, and an entire mask surface 2 11 provided with a backlight 12 for transmitting and irradiating the shadow mask 1 from below to fix the formed shadow mask 1
And a mirror 3 disposed at a position facing the mask surface 2
A camera stage 13 on which the line sensor camera 5 is mounted so as to be movable in an optical axis A direction parallel to the longitudinal direction X of the mask surface 2; a cam 7 for moving the line sensor camera 5 in the optical axis A direction; And a control unit 8 for controlling the rotational position of the step motor 9 and the imaging operation of the line sensor camera 5, and processing the obtained image to inspect the mask surface 2 for defects. And an image processing unit 10 for performing the processing.

As shown in FIG. 2, the line sensor camera 5 is arranged and adjusted so as to capture an image of the mask surface 2 as sharply as possible in a line-shaped visual field over the entire width (Y direction) of the mask surface 2. I have.

The mirror 3 is connected to a rotation shaft 9a of the step motor 9 via a belt 19, rotates around a rotation shaft 3a, and enters the line sensor camera 5 from the mask surface 2 via the mirror 3. The optical path of the light is arranged so as to scan the entire mask surface 2 in the X direction.

The cam 7 is connected to a rotation shaft 9a of the step motor 9 via a belt 18, and rotates around the rotation shaft 7a in conjunction with the mirror 3 to always push the contact portion 15 of the camera stage 13. Moving from the mask surface 2 to the line sensor camera 5
Is adjusted so that the optical path length between the mask surface 2 and the line sensor camera 5 on the center line in the width direction Y of the mask surface 2 is kept constant while the optical path of the light incident on the mask surface 2 scans the entire surface of the mask surface 2. I have.

The camera stage 13 has a contact portion 15 for contacting the cam 7 and has a movable stage 14 on which the line sensor camera 5 is mounted.
The movable stage 14 includes a spring 17 for pressing the movable stage 14 in the optical axis A direction.

According to the shadow mask inspection apparatus of this embodiment, as shown in FIGS. 1 and 2, the optical path of light incident on the line sensor camera 5 from the mask surface 2 is behind the frame 4 of the shaped shadow mask 1. Since the mirror 3 is rotated so as to scan also the mask surface 2 located at the position 2, the both ends 6, 6 of the mask surface 2 can be inspected without being affected by the frame 4 of the formed shadow mask 1. . Further, when the line sensor camera 5 scans the mask surface 2, the optical path length between the mask surface 2 and the line sensor camera 5 is kept almost constant, so that a sharp image can be taken over the entire mask surface 2. .

According to the present invention, the mirror is rotated so that the optical path of the light incident on the line sensor camera from the mask surface also scans the mask surface located behind the frame of the formed shadow mask. The entire surface can be imaged.

In the second embodiment of the present invention, as shown in FIG. 3, a line sensor camera 5 for picking up an image of a mask surface 2 of a molded shadow mask 1 in a line-shaped visual field,
A stage 11 having a backlight 12 for irradiating the entire surface from below and fixing the shaped shadow mask 1, a mirror 3 disposed at a position facing the mask surface 2, a step motor 9 for rotating the mirror 3, A linear servomotor 20 for mounting the line sensor camera 5 so as to be movable in the direction of the optical axis A, control means 22 for controlling the rotation of the step motor 9, the driving of the linear servomotor 20, and the imaging operation of the line sensor camera 5; Image processing means 10 for processing the obtained image to inspect the mask surface 2 for defects.

An encoder 24 for reading the rotation position of the mirror 3 and transmitting the signal to the control means 22 is attached to the rotation shaft 3a of the mirror 3.

The control means 22 has a storage means 23 for storing a data table in which the rotation position of the mirror 3 and the drive position of the movable stator 20a of the linear servomotor 20 are stored.
Using the rotation position of the mirror 3 sent from the encoder 24 as an argument, the linear servo motor 20
Is driven, and the linear servo motor 20 is controlled based on the search result, so that the optical path of light incident on the line sensor camera from the mask surface scans the entire mask surface 2 while the width of the mask surface 2 is being scanned. The optical path length between the mask surface 2 and the line sensor camera 5 on the center line in the direction Y is configured to be kept constant.

In the above embodiment, one line sensor camera is provided, but the present invention is not limited to this.
It is sufficient that the entire surface of the mask can be imaged sharply, and two or more line sensor cameras may be provided as shown in the conventional example.

[0025]

According to the present invention, the mirror is rotated so that the optical path of light incident on the line sensor camera from the mask surface also scans the mask surface located behind the frame of the formed shadow mask. Thus, an image of the entire mask surface can be taken. Therefore, the defect inspection of the entire mask surface can be performed without being affected by the frame of the formed shadow mask.

In the present invention, there is provided driving means for driving the line sensor camera in the direction of its optical axis in synchronization with the rotation of the mirror so as to keep the optical path length between the mask surface and the line sensor camera constant. In this configuration, since the optical path length between the entire mask surface and the line sensor camera is kept substantially constant by the driving means, it is possible to capture a sharp image over the entire mask surface. Therefore, the defect inspection can be performed with substantially the same sensitivity over the entire mask surface.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view in the width direction showing the first embodiment of the present invention.

FIG. 3 is a schematic longitudinal sectional view showing a second embodiment of the present invention.

FIG. 4 is a schematic perspective view showing a conventional example.

FIG. 5 is a schematic longitudinal sectional view showing a conventional example.

FIG. 6 is a schematic cross-sectional view in the width direction showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Molded shadow mask 2 Mask surface 3 Mirror 5 Line sensor camera 7 Cam 9 Step motor 13 Camera stage A Optical axis direction

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsuyoshi Nomura 1006 Kazuma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A shadow mask inspection apparatus for inspecting a mask surface of a molded shadow mask for defects, a mirror disposed at a position facing the mask surface, and a line sensor camera from the mask surface via the mirror. And a rotating means for rotating the mirror so that an optical path of light incident on the mirror scans the entire mask surface. 2. A driving means for driving the line sensor camera in the optical axis direction in synchronization with the rotation of a mirror so as to keep the optical path length between the mask surface and the line sensor camera constant. Shadow mask inspection equipment. 3. The shadow mask inspection apparatus according to claim 2, wherein the driving means has a cam which rotates together with the mirror, and a connecting means which is guided by the cam surface and drives the line sensor camera in the optical axis direction. 4. The driving means has a sensor for reading the turning position of the mirror, and a camera moving means for driving the line sensor camera in the optical axis direction by a distance corresponding to the turning position read by the sensor. The shadow mask inspection apparatus according to claim 2. 5. The shadow mask according to claim 1, wherein the rotating means is configured to rotate the mirror so that an optical path on the mask surface is scanned at a constant speed. Inspection equipment.