JPH057813B2 - - Google Patents

Description

TECHNICAL FIELD The present invention relates to a cathode ray tube (CRT) display screen inspection system. The method according to the present invention is used when inspecting display screen distortion as part of the inspection process in CRT manufacturing. In the above-mentioned inspection process, as shown in Fig. 3, which will be described later, the rectangular pattern for inspection displayed on the CRT to be inspected is photographed with a television camera, binarized, temporarily stored in memory, and read out. The pass/fail of the rectangular pattern for inspection is determined based on the change in line density. Here, the line density is the value obtained by dividing the total value of the black pixels stored in the memory on a virtual straight line in the memory by the thickness of one line of a normal rectangular pattern on the CRT. say. Therefore, a line density of 1 means that there is one black pixel on one line, and a line density of 2 means that there are 2 black pixels on one line.
It means to be.

Therefore, the point where the linear density changes from 1 to 2 is the point where the linear density on the virtual straight line is 1 when the virtual straight line on the memory is moved without changing the scanning direction.
It means the position of a black pixel on the last virtual straight line whose line density is "1" when changing from "1" to "2". Also, the point at which the linear density changes from 2 to 1 is the point at which the linear density changes from 2 to 1 when a virtual straight line is moved in a direction perpendicular to the direction of the straight line. It means the position of a black pixel on the first virtual straight line that is "1".

Prior Art and Problems Conventionally, a method has been used to inspect a CRT display screen, in which a rectangular pattern for inspection is displayed on a CRT for inspection, and end points of the displayed pattern are extracted. 1st, 2nd
The figure is a diagram illustrating a conventional method for extracting end points of a rectangular pattern. Figure 1 a and b show the case where the corners of the pattern are not rounded due to distortion of the display screen, and the line density is measured by scanning in diagonal directions (a), (b), and (c) with respect to the pattern. Then, a diagonal line (B) with a line density of 1 is detected, and then, as shown in FIG. 1B, the position of the end point on the display screen is detected from the end point position P on the scanned diagonal line (B). FIGS. 2a and 2b show cases in which the corners of the pattern are rounded due to distortion of the display screen. In this case, there is no point on the diagonal line with respect to the pattern where the line density is 1. i.e. diagonal line
When shifting (a), (b), and (c), an end point will exist on the diagonal line (b) that is not 0 for the first time. In other words, the diagonal line
(b) Due to the rounded corners on the top, there are multiple display points P ₁ , P ₂ , and P ₃ as shown in Figure 2b.
It is impossible to determine which display points are endpoints. In this way, when the CRT display screen is distorted and the corners of the inspection rectangular pattern are rounded, there is a problem that the end points cannot be detected accurately.

Purpose of the Invention The purpose of the present invention is to enable a method for accurately extracting end points from diagonal line density by extending and displaying horizontal or vertical line segments of a rectangular inspection pattern, and thereby displaying a CRT display. An object of the present invention is to provide a CRT display screen inspection method that enables accurate screen inspection.

Structure of the Invention According to the present invention, in a cathode ray tube display screen inspection method for inspecting a screen displayed on a cathode ray tube to be inspected, the vertical or horizontal sides of the cathode ray tube to be inspected are set to a predetermined length. Displaying a test rectangular pattern having an extended line segment, scanning in a diagonal direction so as to intersect the line segment and the side, and detecting a point where the line density changes from 1 to 2 or from 2 to 1 due to the scanning, The present invention is constructed by providing a cathode ray tube display screen inspection method characterized by extracting end points of the inspection rectangular pattern using the points.

Embodiment FIG. 3 is a block diagram showing an apparatus for implementing the CRT display screen inspection method according to the present invention. In FIG. 3, a rectangular pattern for inspection, in which line segments are extended in the vertical or horizontal direction, is output from the display pattern instruction circuit 1 to the CRT 2 to be inspected. The rectangular pattern displayed on the CRT 2 is imaged by an imaging device 3 such as a television camera, converted into a binary pattern by a binarization circuit 4, and then stored in a display screen storage section 5. The binarized pattern stored in 5 is sent to the lower left diagonal direction density detection section 6 (i.e., the first linear density detection section), and the line density by scanning in the lower left diagonal direction, that is, one scanning direction, is detected. ,
In particular, it is determined whether the linear density changes from 1 to 2 or not. When the value changes from 1 to 2, the display point data on the diagonal line at the change point is sent to the end point coordinate determination circuit 8, and the coordinates of the end point on the display pattern are determined. If the linear density due to scanning in the lower left diagonal direction does not change from 1 to 2, the lower right diagonal linear density detection unit 7
(i.e., the second linear density detection section) is activated, i.e.,
Display point data on the diagonal line where the line density in the other scanning direction perpendicularly intersecting the one scanning direction changes from 1 to 2 is sent to 8, and the coordinates of the end points on the display pattern are determined. The coordinates of the end points determined by the end point coordinate determination circuit 8 are sent to the CRT pass/fail judgment section 9 together with the binarized pattern of the display screen in step 5 and the display pattern command instructed to display in step 1, and are sent to the CRT pass/fail judgment section 9 to determine whether the CRT 2 is passed or not. It is determined whether
The determination result is stored in the determination result storage section 10. In the above example, the line density by scanning in the lower left diagonal direction is detected first, but the effect is exactly the same even if the line density in the lower right diagonal direction is detected first.

4 and 5 are diagrams illustrating an end point extraction method performed using the apparatus shown in FIG. 3. Figure 4a,
b is a case where the corners of the rectangular pattern T for inspection are not rounded due to distortion of the display screen. L is an extension line segment of the pattern T extended in the vertical direction. In this case, the line density due to diagonal scanning is
Since it changes from 1 to 2 along the diagonal line (c) with the boundary between can. FIGS. 5a to 5d show cases in which the corners of the pattern are rounded due to distortion of the display screen. In this case, the extended line segment L is also displayed with distortion.
The line density due to scanning in the lower left diagonal direction changes from 1 to 3 at the diagonal line (b), and the display points P ₁ , P ₂ , and P ₃ are shown as shown in Figure 5b, and with this much information, it is not possible to accurately It is not possible to determine the location of the endpoints.
Therefore, as shown in FIG. 5c, the line densities (A), (B), and (C) are determined by scanning in the lower right diagonal direction. In this case, the line density changes from 2 to 1 on the diagonal line (b), which allows the positions of the end points of the pattern to be accurately determined as shown in FIG. 5d.

Effects of the Invention According to the present invention, the end points of a rectangular pattern for inspection can be extracted accurately regardless of the distortion of the CRT display screen, so that the CRT display screen can be accurately inspected.

[Brief explanation of the drawing]

Figure 1 a, b and Figure 2 a, b show the conventional
FIG. 3 is a block diagram showing an apparatus for carrying out the CRT display screen inspection method according to the present invention, and FIGS. 5
FIGS. a to d are diagrams illustrating a method for extracting end points of a rectangular pattern performed using the apparatus shown in FIG. 3. Explanation of symbols, 1...Display pattern instruction circuit, 2
...Inspection CRT, 3...Imaging device, 4...Binarization circuit, 5...Display screen storage section, 6...Lower left diagonal line density detection section, 7...Lower right diagonal line density detection section , 8... End point coordinate determining circuit, 9... CRT pass/fail determining unit, 10... Judgment result storage unit.

Claims (1)

[Scope of Claims] 1. A cathode ray tube display screen inspection method for inspecting a screen displayed on a cathode ray tube for inspection, comprising: a photographing unit for photographing a rectangular pattern for inspection displayed on the screen of the cathode ray tube for inspection; A binarization unit that binarizes the photographed rectangular pattern for inspection; a display screen storage unit that stores the binarized display image; A value obtained by dividing the total value of the stored black pixels on a straight line on the memory by the thickness of one line of a normal rectangular pattern on the screen of the cathode ray tube is detected as the linear density, and a first linear density detection unit that detects a change in the linear density when the upper straight line is moved in the one scanning direction; and another scanning direction that intersects perpendicularly with the one scanning direction on the screen. , the linear density is the value obtained by dividing the total value of the black pixels stored in the display screen storage unit on a straight line on the memory by the thickness of one line of a normal rectangular pattern on the screen of the cathode ray tube. a second line density detection unit that detects a change in the line density when the straight line on the memory is moved in the other scanning direction; an end point coordinate determination unit for determining the coordinates of end points of the test pattern, displays a test rectangular pattern having a line segment with a vertical or horizontal side extended to a predetermined length on the test cathode ray tube, and The first linear density detection section detects a point where the linear density changes from 1 to 2, and the second linear density detection section detects the linear density. A cathode ray tube display screen inspection method characterized by detecting points that change from 2 to 1 and extracting end points of the inspection rectangular pattern from these detected points.