JPH0638248A - Mis-convergence measurement method - Google Patents

Abstract

PURPOSE:To reduce the measurement time and to improve the measurement accuracy by measuring in advance position data of fluorescent dots of each color of a color cathode ray tube to be checked and implementing color discrimination processing based on the position data at the measurement. CONSTITUTION:A video signal of a white/black camera 4 is stored in memories 7a-7d depending on a video image by a memory selection section 6 via a picture processing section. A color demultiplex section 8 collates the content of any memory among color dependent fluorescent dot position data memories 7a-7c when a CPU 9 reads the measurement pattern data memory 7d and extracts only brightness data of a color to be collated in the memory 7d. Thus, the brightness of the part other than the fluorescent dot of a designated color is set to 0 and read by the CPU 9. The CPU 9 calculates the brightness distribution center of each color based on the brightness distribution information of the measurement pattern subject to color separation, obtains a relative position shift of the brightness distribution center of each color and displays it on a display section 10 as a mis-convergence quantity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring misconvergence of a color blank tube.

[0002]

2. Description of the Related Art As a conventional misconvergence measuring method, for example, there is one described in JP-A-61-257096. According to this method, the measurement pattern is displayed in all color emission states. The image is taken using a black and white camera.The red, green, and blue optical filters are provided on the front of the camera, and these are sequentially switched to capture the image, and the center of the luminance distribution for each color is obtained. From this, the misconvergence amount is calculated.

As another method, JP-A-1-204595
In the method described in (1), the measurement pattern in the light emission state of all colors is color-separated by a color camera, the luminance distribution center for each color is obtained, and the misconvergence amount is calculated.

[0004]

In the above-mentioned conventional technique, in the method using the optical filter, not only does it take time to switch the filters, but it is necessary to capture the image three times to perform one convergence measurement. It was not suitable for high speed measurement. Further, since images of respective colors are taken in at different timings, there is a problem that measurement accuracy is deteriorated due to the influence of variations in the deflection system on the color television side. On the other hand, in the method using a color camera, when a general color camera is used, the resolution is considerably lower than that in a monochrome camera, so that the measurement accuracy does not increase so much. Moreover, it has become possible to obtain a resolution comparable to that of a monochrome camera by using a high-quality color camera, but there is a problem in that it is difficult to use because of its cost being about 10 times that of a monochrome camera. An object of the present invention is to provide a misconvergence measuring method for a color television, which can measure the misconvergence by using a monochrome camera only once to capture an image, and can reduce the cost of the device and shorten the measuring time. Especially.

[0005]

In order to achieve the above object, the method of measuring misconvergence of the present invention causes a monochrome raster of red, green, and blue to be sequentially projected on the surface of a color cathode ray tube to be inspected, and this is displayed by a monochrome camera. Positional data of fluorescent dots for each color in the field of view is stored in advance. At the time of misconvergence measurement, a measurement pattern (a red, green, and blue simultaneous light emission state lattice pattern) is displayed on a color cathode ray tube to be inspected, and the black and white camera captures an image of the luminance distribution center position for each color. At this time, the center of the luminance distribution for each color is obtained by performing the weighted average processing of the luminance using the luminance distribution data of the measurement pattern and the position data of the fluorescent dot for each color described above as the color discrimination information to obtain the misconvergence amount. It was done like this.

[0006]

The above-mentioned misconvergence measuring method is performed by measuring the position data of the fluorescent dots of each color of the inspected color CRT within the measurement field of view in advance, and performing color discrimination processing based on this position data at the time of measurement, so that each color is processed. Since the central position of the luminance distribution can be obtained, misconvergence measurement can be performed by capturing the image once, so that the measurement time can be shortened and the measurement accuracy can be improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an overall configuration diagram of the present invention. In FIG. 1, the function and operation of each unit will be described first. The signal generator 1 displays a single color (red, green,
The color television 3 is supplied with a video signal for displaying a blue or raster or measurement pattern (red, green, blue, lattice pattern of simultaneous light emission). The monochrome camera 4 is provided with a positioning means and an imaging optical system (not shown) so that the color cathode ray tube 2 can capture an image of a predetermined area of the measurement pattern. The image signal of the monochrome camera 4 is binarized or digitized into 256 gradations in the image processing unit 5, and is stored in the memories 7a, 7b, 7c and 7d for each image displayed on the color CRT 2 by the memory selection unit 6. The memories 7a, 7b, 7c are red, green, and blue fluorescent dot position data memories, respectively, and have a frame memory structure of 512 × 512 × 1 bit. The memory 7d is for storing the luminance distribution of the measurement pattern, and has a frame memory configuration of 512 × 512 × 8 bits. The color separation unit 8 is a CPU
When 9 reads the contents of the measurement pattern data memory 7d,
A function to extract only the brightness data of the fluorescent dots of the color to be collated in the measurement pattern data memory 7d by collating the contents of any one of the color-dependent fluorescence dot position data memories 7a, 7b, 7c. To do.
Therefore, the brightness value of the portion other than the fluorescent dots of the designated color is read into the CPU 9 as 0 (the brighter the brightness value, the higher the brightness value). The CPU 9 calculates the center of the brightness distribution of each color based on the brightness distribution information of the measurement pattern color-separated by the above-described method based on the algorithm described later, obtains the relative position shift amount of the brightness distribution center of each color, and makes a mistake in this. The amount of convergence is displayed on the display unit 10.

Next, the misconvergence measurement algorithm of the present invention will be described in detail. Before measuring, color CRT 2
Red, green, and blue single-color rasters are sequentially projected on the screen to create fluorescent dot position data for each color. FIG. 2 shows a part of the image captured by the monochrome camera 4 on the image projected on the color CRT 2. White raster (color red, green, blue fluorescent dots 11a,
2b when 11b and 11c are illuminated.
As shown in FIG. 2A, when a red monochromatic raster is projected, red fluorescent dots 11a are displayed as shown in FIG. 2B.
Only all of them are in a light emitting state. Similarly, when green and blue monochromatic rasters are projected, they are as shown in FIGS. 2C and 2D, respectively. Taking red as an example of the fluorescent dot position data of each color, a logical 1 is written in the memory address of the memory 7a corresponding to the red fluorescent dot shown in FIG. 2B, and a logical 0 is written in the other portions. Do the same for green and blue. This completes the creation of the fluorescent dot position data for each color of the color CRT 2 within the field of view of the monochrome camera 4.

Next, the grid pattern for measurement shown in FIG. 3A is projected on the color cathode ray tube 2. FIG. 3B shows an image in the visual field captured by the monochrome camera 4. The misconvergence amount is defined as a relative positional shift amount of the grid point coordinates for each color of the grid pattern 12. So Fig. 3
As shown in (b), a vertical line measurement window 13 for obtaining the color-wise luminance distribution center in the horizontal (X) direction and a horizontal line measurement window 14 for obtaining the color-wise luminance distribution center in the vertical (Y) direction are provided. First, a method of measuring the center of the luminance distribution for each color in the lateral direction will be described for red. FIG. 4A shows an image of the vertical line measurement window 13 before color separation, and FIG. 4B shows an image after color separation. First, the vertical lightness sum MVR (x) of the vertical line measurement window image 13 after color separation is obtained. The result is shown in FIG. Using the MVR (x), the red lateral luminance distribution center position XR is calculated by the equation 1.

[0011]

## EQU1 ## XR = .SIGMA.MVR (x) .multidot.x / .SIGMA.MVR (x) Similarly, the horizontal luminance distribution center positions XG and XB of green and blue are obtained.

Next, a method of measuring the center of the luminance distribution for each color in the vertical direction will be described for red. FIG. 5A shows an image of the horizontal line measurement window 14 before color separation, and FIG. 5B shows an image after color separation. First, the horizontal lightness sum MHR (y) of the horizontal line measurement window image 14 after color separation is obtained. FIG. 5 (c)
The results are shown in. Using the MHR (y), the central position YR of the luminance distribution in the vertical direction of red is calculated by the equation 2.

[0013]

## EQU2 ## YR = .SIGMA.MHR (y) .multidot.y / .SIGMA.MHR (y) Similarly, green and blue vertical luminance distribution center positions YG and YB are obtained. Next, the amount of misconvergence is defined by the amount of deviation between red and blue with respect to green.
Therefore, the red and blue lateral misconvergence amounts XRG, XBG and the vertical misconvergence amounts YRG, YBG
Is calculated by Equation 3, Equation 4, Equation 5, and Equation 6, and the result is displayed on the display unit 10.

[0014]

[Formula 3] XRG = XR-XG

[0015]

[Formula 4] XBG = XB-XG

[0016]

[Equation 5] YRG = YR-YG

[0017]

## EQU6 ## YBG = YB-YG When re-measurement is performed without moving the position of the monochrome camera 4, it is not necessary to create fluorescent dot position data for each color thereafter. When the black-and-white camera 4 is moved, it is necessary to create fluorescent dot position data before measurement and then perform measurement.

Further, when the center position of the brightness distribution is obtained, the measurement error due to the background brightness level can be eliminated by finding the distribution center of the brightness only for the signal component having the background brightness level or higher in the video signal of the camera. It will be possible. This method will be described with reference to FIG. For the sake of convenience of explanation, only the vertical luminance distribution center position will be described, but the same idea is applied to the measurement of the luminance distribution center positions of other colors.

FIG. 6A shows a red fluorescent dot 11a and a green fluorescent dot 11 in the horizontal line measuring window 14 of FIG. 3B.
The light emitting states of b and the blue fluorescent dot 11c are shown. In the figure, it is assumed that the hatched portion of each fluorescent dot is emitting light.
FIG. 6B shows the video signal level M1 (y) of the monochrome camera 4 on the line ab in FIG. 6A. As can be seen from the figure, the video signal level is not 0 at positions other than the portion where the red fluorescent dots are emitting light. This is because the offset of the background lightness level 15 corresponding to the dark current of the black and white camera 4 appears as the image signal level is added. FIG. 6C shows the video signal level higher than the threshold level 16 set to a level slightly higher than the background lightness level for the video signal of FIG. Regarding the signal level, the video signal level M2 (y) after the background level removal, which has been processed to be 0, is shown.

[0020]

[Equation 7] M2 (y) = M1 (y) -threshold level

[0021]

According to the present invention, a black and white camera is used to
Since it is possible to measure the misconvergence of the color TV by capturing the image once, there is an effect that the measurement time can be shortened or the measurement accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an entire apparatus showing an embodiment of a misconvergence measuring method according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between emission states of fluorescent dots when a white raster is projected on a color CRT surface and when a single color raster is projected.

3 is an explanatory diagram showing an image of a measurement pattern imaged by the camera of FIG. 1 and a method of setting a measurement window.

FIG. 4 is an explanatory diagram showing a method for obtaining a center position of a red luminance distribution of a vertical line in FIG.

FIG. 5 is an explanatory diagram showing a method of obtaining the center position of the red luminance distribution of the horizontal line in FIG.

FIG. 6 is an explanatory diagram showing a method of removing a measurement error due to a dark current of a camera when obtaining the luminance distribution center position shown in FIGS. 4 and 5;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Signal generator, 2 ... Color CRT, 3 ... Color TV, 4 ... Monochrome camera, 5 ... Image processing part, 6 ... Memory selection part, 7a ... Red fluorescent dot position data memory, 7b ...
Green fluorescent dot position data memory, 7c ... Blue fluorescent dot position data memory, 7d ... Measurement pattern data memory, 8 ... Color separation unit, 9 ... CPU, 10 ... Display unit, 11a
... Red fluorescent dots, 11b ... Green fluorescent dots, 11c ...
Blue fluorescent dots, 12 ... Measurement pattern, 13 ... Vertical line measurement window, 14 ... Horizontal line measurement window, 15 ... Background brightness level, 16 ... Threshold level.

Claims (1)

[Claims] 1. A means for projecting a monochrome raster on a surface of a color cathode ray tube to be inspected, picking up the image with a monochrome camera, and storing the position data of the red, green and blue fluorescent dots of the color cathode ray tube in the field of view of the camera. And the measurement pattern on the surface of the color cathode ray tube in all color emission states (red,
A green and blue simultaneous light emission state) is displayed, the black and white camera captures an image of the light emission luminance distribution, and the light emission luminance distribution of the measurement pattern is colored based on the fluorescent dot position data for each color. A misconvergence measuring method, characterized in that means for separately separating and a brightness center of an emission brightness distribution for each color are calculated, and a relative positional deviation amount of the center position is calculated as a misconvergence amount.