JP2001015032A - Inspection method of cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide inspect a defect of a fluorescent film of a cathode-ray tube. SOLUTION: An inspection device 10 is provided with a light emitting device 23 for emitting light from phosphors having respective colors of a fluorescent film 14 of a cathode-ray tube 11, and a CCD camera 25 for photographing the fluorescent film 14. Thereby, a part having a luminance different from that of other parts over a predetermined range can be determined. When interference fringes are produced in the image of the CCD camera 25 due to the relations between the interval of dots of the fluorescent film 14 and the interval of the picture elements of the CCD camera 25, an optical system 28 of the CCD camera 25 is adjusted eliminate the interference fringes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a cathode ray tube, for example, for inspecting whether a desired pattern is formed in a process of manufacturing a cathode ray tube.

[0002]

2. Description of the Related Art Conventionally, in the final inspection stage of the manufacturing process of a cathode ray tube such as a color cathode ray tube, inspection for defects generated in the manufacturing process on the fluorescent film and the glass panel surface of the cathode ray tube is generally performed. In this inspection, the blue (B), red (R), and green (G) phosphors of the fluorescent film are illuminated one by one, and all the dots of each color are illuminated entirely, Inspection is performed to confirm that light emission is not inhibited by contamination.

In this inspection, a CCD camera including an effective light emitting area of a cathode ray tube in a visual field is installed, an image of a light emitting surface is taken, and based on the image data, each of blue, red, and green phosphors is taken. A configuration for detecting a defect and improving the inspection accuracy has been considered. Then, in this configuration, in the inspection, the luminance of the light emitting surface of each color is adjusted by a device that makes the cathode ray tube emit light, and the image on the light emitting surface is maintained at a uniform brightness. In this state, the defective portion is shown to be darker or brighter than the uniform surrounding brightness. In other words, when an image captured by a CCD camera is used as an image processing apparatus and a gray level is assigned to each brightness, a defect portion is more than a preset threshold with respect to a uniform average gray level of the light emitting portion. Indicates a low or high gradation difference.

[0004]

However, in the above-mentioned conventional configuration, the uniformity of the light emitting portion determines the accuracy of the measurement, it is necessary to make the light emitting surface emit light uniformly, and the phosphor of each color of the fluorescent film is required. Depending on the relationship between the pitch of the dots of the CCD camera and the pitch of the pixels of the CCD camera, interference fringes occur in the image signal of the CCD camera. There is a problem that the tone is not uniform and the accuracy of defect inspection is reduced due to interference fringes.

The present invention has been made in view of the above points, and provides a method of inspecting a cathode ray tube capable of accurately inspecting a pattern regularly arranged on a display surface of the cathode ray tube by using an image pickup means. The purpose is to:

[0006]

According to the method of inspecting a cathode ray tube of the present invention, a pattern regularly arranged on a display surface of the cathode ray tube is imaged by an imaging means having pixels regularly arranged on an imaging surface. A method of inspecting a cathode ray tube using the image signal obtained, wherein the inspection is performed in a state where the size of an image of the pattern reflected on the imaging surface is changed and interference fringes generated in the image signal are suppressed. It is.

In this configuration, a pattern composed of a plurality of dots of the phosphor formed on the fluorescent film is inspected while the fluorescent film emits light. In addition, a pattern formed by a plurality of dots formed in the shadow mask is inspected for transmitted light transmitted through the through hole while illuminating the shadow mask from the opposite side of the imaging unit.

Then, the size of the image of the pattern reflected on the imaging surface is adjusted, and the pitch of the dot image of the pattern is made equal to the pitch of the pixel of the imaging means, or the pitch of the image of the dot of the pattern is adjusted. By performing the inspection in a state where the pitch of the pixels of the imaging unit is relatively an integral multiple, a state in which interference fringes are suppressed is realized.

In the method of inspecting a cathode ray tube, a CCD having pixels generally arranged in a grid is generally used.
High-precision inspection can be performed by using an imaging unit that is a camera.

[0010] The size of the image of the pattern reflected on the image pickup surface is adjusted by an optical system or by changing the distance between the display surface and the image pickup surface.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a method and apparatus for inspecting a cathode ray tube according to the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 10 denotes an inspection device. The inspection device 10 is, for example, a cathode ray tube (c) which is a color CRT.
(athode-ray tube) 11 Used for shipping inspection etc. after the final process of manufacturing, and inspects the fluorescent film 14 which is the fluorescent screen constituting the display surface 12 to be inspected formed on the inner surface of the panel for defects in the fluorescent film 14. Is what you do.

The inspection apparatus 10 includes an arithmetic device 21 which is a control device having a CPU and the like, and an image processing device 22 and a light emitting device 23 connected to the arithmetic device 21. Further, the image processing device 22 includes a CC
D (charge coupled device) A camera 25 is connected, and the light emitting device 23 has a connector electrically connected to the cathode ray tube 11.
26 is connected. Although not shown, the arithmetic unit 21
Is connected to a display device and an operating device for the operator.

The cathode ray tube 11 is connected to a light emitting device 23 via a connector 26, and is controlled by the light emitting device 23 to display a predetermined image, that is, to cause the fluorescent film 14 to emit light in a desired state. It is positioned and supported and fixed at a predetermined position by a support device (not shown).

The CCD camera 25 has a CCD 27 as an image sensor, which is a two-dimensional image sensor, and an optical system 28 such as an electric zoom lens.
That is, it is disposed directly opposite the fluorescent film 14, that is, the CCD
27, the imaging surface 31 is supported and fixed in parallel with the fluorescent film 14 and at the center.

As shown in FIGS. 2 and 3, a large number of rectangular pixels 33 are arranged in a lattice at a predetermined pitch on the imaging surface 31 of the CCD 27 of the CCD camera 25. On the other hand, a large number of dots 35 formed by applying blue (B), red (R), and green (G) phosphors on the fluorescent film 14 of the cathode ray tube 11 are regularly repeated at a predetermined pitch. They are arranged and constitute a predetermined pattern 36. The light emitting device 23 emits a phosphor of any one of these colors.

At the time of inspection, the cathode ray tube 11 is positioned and fixed at a predetermined position by a support device, connected to the light emitting device 23 via the connector 26, and the CCD camera 25 is attached to the display surface 12 of the cathode ray tube 11. Fix facing up. In this state, the arithmetic unit 21 operates the light emitting device 23 to display a predetermined image. In other words, the electron gun of the cathode ray tube 11 is operated to emit the phosphor dots 35 of the phosphor film 14 so that the overall luminance becomes uniform for each color.

On the other hand, the CCD camera 25 is set so as to be focused on the fluorescent film 14, and captures the light emission state of each color on the imaging surface 31 of the CCD 27. Then, the captured image signal is
The image is processed by the image processing device 22 and further processed by the arithmetic device 21 to measure the luminance at each position on the surface of the fluorescent film 14, as shown in FIGS. 4 and 5 show only measurement results on a specific line segment for explanation. Then, as a result of this measurement, if there is no defect in the fluorescent film 14 or the like, a value close to a standard value which is a constant value is shown over the entire surface. When the phosphor of the fluorescent film 14 emits light, the position of the defect is shown by adjusting the light emitting device 23 so that the luminance of the fluorescent film 14 approaches a constant value over the entire surface. Then, as shown in FIG. 4, when a portion indicating a value that deviates upward and downward beyond an upper limit value or a lower limit value set in a predetermined range set in advance from a standard value that is a constant value is detected, The arithmetic unit 21
Processing such as displaying the position of the defect, or transporting the cathode ray tube 11 to a correction process based on a predetermined determination is performed.

Here, in terms of the accuracy of the inspection, the arrangement, that is, the pitch of the pixels 33 on the imaging surface 31 of the CCD 27 of the CCD camera 25 and the dots 35 of the fluorescent film 14 are adjusted so that one pixel per dot 35 It is suitable to place 33. That is, for example, as shown in FIG.
An ideal resolution is to set the resolution so that one pixel 33 corresponds to one dot 35.

However, in actual inspection, the fluorescent film 14
The distance between the camera and the CCD camera 25 is not set strictly.
When the distance slightly changes, as shown in FIG. 3, a shift occurs between the pixel 33 and the dot 35 on the imaging surface 31. When the pitch is close, as a result of integration of the shift, the entire image signal is output. In some cases, moire-shaped interference fringes may occur in a certain direction or on the circumference.

In the state where the interference fringes are thus generated, as shown in FIG. 5, the luminance of the background, which should have been adjusted uniformly, varies with a certain regularity, indicating a defect. Affects signal detection.

Therefore, in this embodiment, a CCD camera
Adjust the optical system 28 manually or automatically, that is, change the resolution, for example, in the case of manual, adjust the zoom while watching the image captured by the CCD camera 25 displayed on the display device, The state of FIG. 5 is adjusted to the state of FIG. 4 by changing the size of the dots 35 on the imaging surface 31 to eliminate the interference fringes of the entire image. Then, when the captured image is viewed in a minimum state in this adjusted state, as shown in FIG. 2, one dot 35 is adjusted so as to correspond to one pixel 33. By performing the inspection under this adjusted state, an inspection with high accuracy can be performed.

As described above, the fluorescent film of the cathode ray tube 11 of the present invention
According to the inspection method 14, in the manufacturing process of the cathode ray tube 11, in the inspection using the CCD camera 25, the uniformity of the captured image can be improved by performing adjustment to eliminate the interference fringes, A defect of the fluorescent film 14 can be inspected manually or automatically with high accuracy, and a highly reliable method and apparatus for inspecting the fluorescent film 14 of the cathode ray tube 11 can be constructed and provided.
For this reason, a stable inspection with few oversights can be realized as compared with an inspection relying on humans, and the industrial value is high.

In the above embodiment, the pitch between the regularly arranged dots 35 and the pixels 33 is adjusted so that one dot 35 corresponds to one pixel 33. The interference fringes have been eliminated, but the present invention is not limited to this.By setting the pitch of the regularly arranged dots 35 and the pitch of the pixels 33 to be any positive multiple, a similar effect can be realized. Defects can be inspected with high accuracy by improving the uniformity of the captured image. Further, even while clearly different from the same pitch and a pitch of an integer multiple, working while observing interference fringes displayed on a display device, for example,
By eliminating interference fringes, a similar effect can be realized,
That is, the uniformity of the captured image is improved, and the defect can be inspected with high accuracy.

Further, a CCD camera 25 as an image pickup means
Has been adjusted to eliminate the interference fringes by adjusting the optical system 28, but any device that changes the optical conditions may be used.For example, any one of the imaging unit and the cathode ray tube 11 can be moved. To change the distance between the display surface 12 and the imaging surface 31,
The size of the image of the pattern 36 on the imaging surface 31 can also be changed.

Further, the image pickup means is not limited to the CCD camera 25, but may be one having pixels regularly arranged at a predetermined pitch.

In the above-described embodiment, the inspection of the fluorescent film 14 performed by emitting light from the phosphor has been described. However, the present invention is not limited to this, and the inspection object can be applied to the inspection of a shadow mask. Effect can be realized.

In the case of shadow mask inspection,
For example, before incorporating the shadow mask into the panel, a planar illumination device is arranged at a position opposite to the CCD camera 25 with respect to the shadow mask, and light emitted from the illumination device is transmitted as dots of the shadow mask. The light passing through the holes and the light passing through each of the holes is imaged by the imaging means, the interference fringes are eliminated, the uniformity of the captured image is improved, and the defect can be inspected accurately.

[0029]

According to the cathode ray tube inspection method of the present invention,
A cathode ray tube inspection method for inspecting a pattern regularly arranged on a display surface of a cathode ray tube using an image signal imaged by an imaging unit having pixels regularly arranged on an imaging surface is shown on an imaging surface. Change the size of the image of the pattern,
By performing the inspection while suppressing the interference fringes generated in the image signal, the accuracy of the pattern inspection can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an inspection apparatus showing an embodiment of a cathode ray tube inspection method according to the present invention.

FIG. 2 is an explanatory diagram of an imaging surface showing an ideal inspection state of the cathode ray tube inspection method.

FIG. 3 is an explanatory diagram of an imaging surface showing an inspection state in which interference fringes are generated in the cathode ray tube inspection method.

FIG. 4 is an explanatory diagram showing an ideal inspection state of the inspection method of the cathode ray tube.

FIG. 5 is an explanatory diagram showing an inspection state in which interference fringes have occurred in the cathode ray tube inspection method.

[Explanation of symbols]

 11 Cathode ray tube 12 Display surface 14 Fluorescent film 25 CCD camera as imaging means 28 Optical system 31 Imaging surface 33 Pixel 36 Pattern

Claims (8)

[Claims] 1. A cathode ray tube inspection method for inspecting a pattern regularly arranged on a display surface of a cathode ray tube using an image signal picked up by an image pickup means having pixels arranged regularly on an image pickup surface. In the state where the size of the image of the pattern reflected on the imaging surface is changed and interference fringes generated in the image signal are suppressed,
An inspection method of a cathode ray tube, characterized by inspecting. 2. The method for inspecting a cathode ray tube according to claim 1, wherein the pattern is composed of a plurality of dots of a phosphor formed on the fluorescent film, and the fluorescent film is inspected while emitting light. 3. The inspection of a cathode ray tube according to claim 1, wherein the pattern is constituted by a plurality of dots formed in the shadow mask, and the inspection is performed while illuminating the shadow mask from the opposite side of the imaging means. Method. 4. The inspection method of a cathode ray tube according to claim 1, wherein the inspection is performed in a state where the pitch of the image of the dot of the pattern matches the pitch of the pixels of the imaging means. 5. The inspection of a cathode ray tube according to claim 1, wherein the inspection is performed in a state where the pitch of the image of the dots of the pattern and the pitch of the pixels of the imaging means are relatively integer multiples. Method. 6. The method according to claim 1, wherein the imaging means is a CCD camera having pixels arranged in a grid. 7. The method for inspecting a cathode ray tube according to claim 1, wherein the size of a pattern image is changed by an optical system. 8. The method for inspecting a cathode ray tube according to claim 1, wherein the distance between the display surface and the imaging surface is changed to change the size of a pattern image.