KR100274994B1 - Focus inspection equipment of crt and its inspection method - Google Patents

Abstract

PURPOSE: A CRT focus testing apparatus is provided to be capable of testing a focus state of a CRT with high reliability. CONSTITUTION: A pattern generator(1) generates a test pattern, and a test pattern display part(3) displays the test pattern generated from the pattern generator(1) on a CRT(5). A pickup part(7) picks up the test pattern displayed on the CRT(5). A pickup width measuring part(11) measures a pickup width of the test pattern taken by the pickup part(7) and has a brightness detecting part(12) and a threshold value brightness calculating part(13). A focus state judging part(21) has a proportional factor storing part(22), a display width conversion part(23), and a width comparison part(24) and judges a focus state based on the pickup width measured by the pickup width measuring part(11) and a target width of the test pattern generated from the pattern generator(1).

Description

Crt focus inspection device and inspection method

The present invention relates to a focus inspection apparatus of a CRT (Cathode Ray Tube) and an inspection method thereof.

The CRT displays a black-and-white image signal or a color image signal, and the focusing of the displayed image signal, that is, the focus state, is inspected before shipment as a product, and the inspection of the focus state in the prior art was dependent on the human eye. . The conventional focus inspection method will be described in detail. First, the production-completed CRT is transferred to the inspection position, and then the inspection pattern generated by the pattern generator is displayed on the CRT. Subsequently, the inspector visually observed the luminance distribution of the inspection pattern displayed on the CRT while adjusting the focus adjustment volume, and empirically judged whether the focus state was on the basis of the luminance distribution.

However, since the luminance of the image on the CRT varies depending on the supply voltage, contrast, etc. of the CRT and can be observed differently by the inspector, according to the conventional CRT focus inspection method, the inspection result of the CRT focus state There was a problem that the reliability is low.

Accordingly, an object of the present invention is to provide a CRT focus inspection apparatus and an inspection method thereof capable of inspecting a CRT focus state with high reliability.

1 is a block diagram schematically showing the configuration of a focus inspection apparatus of a CRT according to the present invention;

2 is a view showing an example of an inspection pattern photographed according to the present invention;

3 is a histograph showing the luminance distribution of the captured image detected by scanning in the arrow direction of FIG. 2;

4 is a diagram illustrating luminance values of a captured image detected by scanning in the direction of the arrow of FIG. 2;

5 is a flowchart of a focus inspection method of a CRT according to the present invention.

<Explanation of symbols for main parts of drawing>

1: pattern generator 3: inspection pattern display

5: CRT 7: Imager

9 display device 11 imaging width measuring unit

12: luminance detector 13: threshold luminance calculator

21: focus state determination unit 22: proportional constant storage unit

23: display width conversion unit 24: width comparison unit

The above object is, according to the present invention, a focus inspection method of a CRT, comprising: generating an inspection pattern having a predetermined target width; Displaying the inspection pattern on the CRT; Imaging the display pattern on the CRT; Measuring an imaging width of the captured display pattern; And determining the focus state of the CRT based on the measured imaging width and the target width.

Here, the determining may include converting the measured image capturing width into a value of the display width on the CRT, and comparing the converted display width value with the target value. In the converting step, a proportionality constant between the image capturing width and the display width may be obtained in advance, and the value of the display width on the CRT may be obtained by multiplying the measured image capturing width by the proportional constant.

The measuring of the image capturing width may include obtaining a threshold luminance for setting a width boundary at both side width boundary regions of the captured display pattern, and imaging the width in the width boundary obtained based on the threshold luminance. And measuring as a width, wherein in the step of obtaining the threshold value, the luminance value is detected within a predetermined range including the imaged pattern, and the luminance distribution is based on the detected luminance value. After creating the histograph, a luminance value representing the maximum slope can be taken as the threshold luminance in a section between the zero point on the histograph and the maximum degree luminance value.

On the other hand, according to another field of the present invention, the above object is a focus inspection apparatus of a CRT, comprising: a pattern generator for generating an inspection pattern having a predetermined target width; An inspection pattern display unit for displaying the inspection pattern on the CRT; An image pickup device for picking up the display pattern on the CRT; An imaging width measuring unit which measures an imaging width of the captured display pattern; The focus inspection apparatus of the CRT includes a focus state determination unit for determining a focus state of the CRT based on the measured imaging width and the target width.

Here, the focus state determining unit may be configured to convert the measured image capturing width into a value of the display width on the CRT, and determine the focus state by comparing the converted display width with the target value. In this case, the proportionality constant between the imaging width and the display width is obtained in advance, and the value of the display width on the CRT can be obtained by multiplying the measured imaging width by the proportional constant.

The image capturing width measuring unit may obtain a threshold luminance for setting a width boundary at both width boundary regions of the captured display pattern, and measure the width in the width boundary obtained based on the threshold luminance as the imaging width. At this time, the luminance value is detected within a predetermined range including the picked-up pattern, a luminance distribution histograph is created based on the detected luminance value, and then between the zero point on the histograph and the maximum dot luminance value. The luminance value representing the maximum slope in the interval of may be referred to as the threshold luminance.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically showing the configuration of a focus inspection apparatus of a CRT according to the present invention. As shown in this figure, the focus inspection apparatus of the CRT according to the present invention includes a pattern generator 1 for generating an inspection pattern and an inspection pattern generated by the pattern generator 1 on the CRT 5. The imaging device 7 has an inspection pattern display section 3 to be displayed, an imaging device 7 for imaging an inspection pattern displayed on the CRT 5, a luminance detection section 12, and a threshold luminance calculation section 13; An image capturing width measuring section 11 for measuring the image capturing width of the inspection pattern photographed by the image, a proportional constant storage section 22, a display width converting section 23, and a width comparing section 24; And a focus state determining unit 21 for determining a focus state based on the imaging width measured in 11) and the target width of the inspection pattern generated by the pattern generator 1. An example of the inspection pattern generated in the pattern generator 1 (S1) is shown in FIG. 2. Fig. 2 is a diagram showing an example of an inspection pattern picked up according to the present invention, wherein reference numeral 7a denotes an image picked up by the imager 7 shown in Fig. 1. As shown in FIG. 2, the inspection pattern is a cross shape which intersects in the center of the imaging screen 7a of the imaging device. This inspection pattern is displayed on the CRT 5 by the pattern display unit 3 (S2), and then imaged by the imaging device 7 (S3). The luminance value of the screen image picked up by the imager 7 is scanned and detected by the luminance detector 12 (S4), and the luminance value of the image screen thus detected is shown in FIG. 4 is a diagram illustrating a luminance value detected by scanning in the direction of an arrow in FIG. 2, in which the horizontal axis of FIG. 4 represents a pixel, the vertical axis represents a magnitude of luminance, and the coordinate zero of FIG. 4 is illustrated in FIG. 2. Each position equals to zero. As shown in Fig. 4, the luminance value of the picked-up screen becomes smaller toward the boundary of the inspection pattern at the zero point in Fig. 2. On the basis of the luminance value detected by the luminance detector 12, a luminance distribution histograph is created by the threshold luminance calculator 13. FIG. 3 shows the luminance of the captured image detected by scanning in the arrow direction of FIG. A histograph showing the distribution. Here, the horizontal axis in Fig. 3 represents the magnitude of luminance, and the vertical axis represents the number of taps, respectively. As shown in Fig. 3, the maximum slope is obtained in the section between the zero point on the histograph and the maximum degree of luminance value, and the luminance value representing the maximum slope is taken as the threshold luminance value (S6). This threshold luminance value is applied to FIG. 4 to measure the imaging width, but the distance between the ABs shown in FIG. 4 becomes the imaging width (S7). The proportional constant between the image capturing width and the display width is previously stored in the proportional constant storage unit 22. In the display width converting unit 23, the proportional constant is multiplied by the distance between the ABs in FIG. 4 on the CRT 5. The display width of the displayed inspection pattern is calculated (S8). The display width calculated by the display width converting section 23 is compared in the width comparing section 24 with the target width of the inspection pattern provided from the pattern generator 1 to the width comparing section 24. The focus state is determined (S9). At this time, both parts of the focus state are determined according to the size of the ratio of the display width to the target width, because the poorer the focus state, the more the inspection pattern is spread and the display width on the CRT 5 increases. The width comparison section 24 calculates the ratio of the display width calculated by the display width conversion section 23 to the target width, and when the ratio is equal to or greater than the predetermined value, the focus state is poor, and when it is lower, the focus state is good. Determine (S6). The determination result of the focus state determination unit 21 is transmitted to the examiner through the display device 9 (S10).

Therefore, according to the present invention, in checking the focus state of the CRT, the reliability of the inspection result can be improved.

Claims (8)

In the focus inspection method of the CRT, Generating a test pattern having a predetermined target width; Displaying the inspection pattern on the CRT; Imaging the display pattern on the CRT; Measuring an imaging width of the captured display pattern; Converting the measured imaging width into a value of the display width on the CRT; And comparing the converted display width with the target value to determine a focus state of the CRT. The method according to claim 1, The step of converting, And obtaining a proportional constant between an image capturing width and a display width in advance, and multiplying the measured image capturing width by the proportional constant to obtain a value of the display width on the CRT. The method according to claim 1, Measuring the imaging width, Obtaining a threshold luminance for setting a width boundary at both side width boundary regions of the captured display pattern; and measuring the width in the width boundary obtained based on the threshold luminance as the imaging width. CRT focus test method. The method according to claim 3, The step of obtaining the threshold, Detecting a luminance value within a predetermined range including a picked-up pattern, creating a luminance distribution histograph based on the detected luminance value, and between the zero point and the maximum frequency luminance value on the histograph And taking the luminance value representing the maximum slope in the interval of as the threshold luminance. In the focus inspection apparatus of the CRT, A pattern generator for generating a test pattern having a predetermined target width; An inspection pattern display unit for displaying the inspection pattern on the CRT; An image pickup device for picking up the display pattern on the CRT; An imaging width measuring unit which measures an imaging width of the captured display pattern; And a focus state determination unit for converting the measured image capturing width into a value of the display width on the CRT, and comparing the converted display width value with a target width to determine a focus state of the CRT. Focus inspection device. The method according to claim 5, The focus state determination unit, And obtaining a proportional constant between the image capturing width and the display width in advance, and multiplying the proportional constant by the measured image capturing width to obtain the value of the display width on the CRT. The method according to claim 5, The imaging width measuring unit, A threshold inspection apparatus for obtaining a threshold boundary for setting a width boundary in both width boundary regions of the captured display pattern, and measuring the width in the width boundary obtained based on the threshold luminance as the imaging width. . The method according to claim 7, The imaging width measuring unit, Detects a luminance value within a predetermined range including the picked-up pattern, creates a luminance distribution histograph based on the detected luminance value, and maximizes the interval between the zero point on the histograph and the maximum frequency luminance value. And a luminance value representing a slope as the threshold luminance.

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