JPH0595568A - Color display device Color shift amount measuring method - Google Patents

Abstract

(57) [Abstract] [Purpose] In measuring the amount of color shift, which is one of the image quality evaluation items for color display tubes, eliminate the influence of the difference in the image capture time in measuring the bright line position of each color, and achieve high accuracy and high speed. Provide a way to measure. [Structure] The bright line is projected and measured. The bright lines of red 22 and blue 23 are displayed by shifting by a predetermined amount. This image is captured by the camera at one time, each bright line position is detected, and the predetermined amount shifted in advance is subtracted from the difference between the positions. The value is the color shift amount to be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image quality adjustment performed when a deflection yoke is attached to a color display tube, and a method for automatically measuring a color shift amount during an image quality inspection.

[0002]

2. Description of the Related Art A conventional measurement is disclosed in JP-A-59-15487.
As shown in Japanese Patent Publication No. 6, in the measurement with a monochrome camera,
On the inspected side, the colors displayed were changed and measured. Alternatively, the colors captured by the color camera are separated and measured.

[0003]

In the method of measuring by color switching, each color is measured at different timings in time, and the accuracy of the value calculated as the amount of color misregistration depends on the difference in the measurement conditions during that time. Can't get For example, the position of the bright line or the position of the camera may change due to fluctuations in the voltage on the side that generates the video signal or external vibrations. Further, in the case of a color camera, an image can be captured at one time, but if an attempt is made to obtain a resolution comparable to that of a monochrome camera, an expensive color camera is required, and further complicated color separation processing is required. Then, it cannot be done with sufficient accuracy.

[0004]

In order to achieve the above object, a bright line to be measured for calculating a color shift amount is projected at a position shifted by a predetermined amount in advance, an image is captured at once with a monochrome camera, and the image is shifted. The amount of color misregistration is calculated by correcting the amount.

[0005]

By projecting the bright lines to be measured in advance, each position can be measured at a time, and the measurement can be performed without being affected by the error due to the difference in the measurement timing. Also, because the emission lines of each are separated,
No need for color separation later.

[0006]

Embodiments of the present invention will be described with reference to FIGS.

According to the present invention, in the assembly of a color display, a deflection yoke is attached to a color display tube,
It is applied to the process of adjusting the image quality and the inspection process of the image quality after some processes. Here, the application to the inspection process after image quality adjustment is taken as an example.

FIG. 2 shows an example of a color display image quality measuring system. The CPU 1, floppy disk controller 2, program memory 3, image input / output circuit 5, image memory 6, and general-purpose input / output circuit 7 are the system bus 8
And are connected to each other via.
In this case, the CPU 1 can be connected with a CRT 9 for inputting / starting a program and displaying a processing result, and further with a printer 10 for outputting a processing result and a program list. Further, the floppy disk controller 2 can be connected with a program, Floppy disk drive for storing data 11
However, it is designed to be connected. For temporary storage of programs or data, the program memory 3
Is provided. Further, the video signal from the camera 14 is input to the image input / output circuit 5, the processed image is displayed on the monitor 13, and the video signal from the camera 14 is digitized into multivalues and then stored in the image memory 6. Is stored.

A predetermined image is generated by the signal generator 12 for generating a signal on the color display tube 15 of the object to be inspected.
It is projected on the color display tube 15. Further, a plurality of cameras 14 can be installed near the surface of the cathode ray tube, and the image input / output circuit 5 is provided by the camera switching circuit.
And connect the specified camera.

The method of measuring the color shift amount will be described in detail below.

The color shift amount is measured as the shift amount of the center of each color of red, green and blue. Therefore, the positions of the bright lines of red, green, and blue are measured, and the difference between the positions is obtained. Therefore, the red bright line 22 and the blue bright line 23 are centered around the green bright line 21,
The image is displayed at a position shifted by a predetermined amount. For example, as shown in FIG. 1, red has a vertical emission line at a position of −dmm with respect to green, blue has a vertical emission line at a position of + dmm, and red has −smm with respect to green.
For m and blue, a horizontal bright line is projected at a position of + smm.
These images are enlarged and taken in close-up by the camera 14 and taken into the image memory 6. The amount of color shift in the horizontal direction is obtained from the image showing the bright lines in the vertical direction, and the amount of color shift in the vertical direction is obtained from the image showing the bright lines in the horizontal direction. Hereinafter, the horizontal direction of this image is set to x and the vertical direction is set to y.

An example will be described in which a bright line in the vertical direction is projected and the color shift amount in the x direction (horizontal direction) is measured.

FIG. 3 shows a flowchart for measuring the amount of color misregistration. First, a signal as shown in FIG. 1 is generated via the signal generator 12. Next, the camera 14 inputs this image. And first, measure the pedestal level of the camera. The output generated when a black object is imaged by a camera is called a pedestal level. Ideally, it is desired that the pedestal level be 0, but usually some output is generated. The pedestal level is not only specific to the camera, but also includes the brightness of the non-luminous area of the display tube surface, but in order to accurately determine the position of the bright line, it is necessary to consider an image from which this pedestal level has been subtracted. Therefore, with respect to the image stored in the image memory 6, the luminance on a specific horizontal line is checked, and the luminance of the darkest point at this time is set as the pedestal level. Then, a value obtained by adding a predetermined threshold value to this value is set as a background level, and the following processing is performed only for the level and above.

Next, a processing window for detecting the bright line position is automatically set. Therefore, first, with respect to the bright line direction, in this case, the projection distribution in the y direction is obtained. At this time, as shown in FIG. 4, the entire range is set in the x direction, and the y direction is set in a window occupying a range (ys to ye) having a certain size.

The leftmost point lt and the rightmost point rt are obtained for this projection distribution. The position obtained by adding the known bright line width wl and the predetermined margin amount b to the leftmost point is defined as x1. Further, a position obtained by adding a previously known bright line width wr and a predetermined margin amount b to the rightmost point is defined as x2. A range defined by x1, x2 and values y0, y1 having an appropriate size in the y direction is set as the green bright line position detection window 31.

Further, a range surrounded by this x1 and a position x0 separated from the leftmost point lt by a predetermined margin amount b value is set as a red luminescent line position detection window 32, and x
Similarly, a range surrounded by 2 and a position x3 distant from the rightmost point rt by a predetermined margin amount b value is similarly set as the red emission line position detection window 33. Then, the center of gravity is obtained in each window, and the green line position Gx and the blue line position B
x, and the position Rx of the red line.

The center of gravity of the bright line is obtained as follows. First, a projection distribution of brightness values is taken in the projection y direction within the window. And its coordinate value i and projection value f
The following calculation is performed on (i) to obtain its centroid value. The center of gravity of the green bright line is calculated by the following formula.

[0018]

[Equation 1]

Bx and Rx are similarly obtained.

From these values, the red-green color shift amount R in the x direction
Gx, blue-green color shift amount BGx, and red-blue color shift amount RBx are calculated according to the following equations.

RGx = Rx−Gx + a BGx = Bx−Gx−a RBx = Rx−Gx + 2a (2) Similarly, a horizontal bright line position in which the blue and red positions are shifted is captured, and the position of the green bright line in the y direction is captured. Gy, red emission line position Ry,
The blue bright line position By is obtained, and the red-green color shift amount RGy, the blue-green color shift amount BGy, and the red-blue color shift amount RBy are calculated.

In some cases, the color shift amount may be desired to be calculated only for the red and green shift amounts. In this case as well, similarly, the red and blue bright lines are projected apart by a predetermined distance, the positions of the respective bright lines are obtained, and the color shift amount is calculated.

[0023]

EFFECTS OF THE INVENTION In the measurement of the image quality of a color display device, when a bright line to be measured is projected, the projected position is changed for each bright line of a different color, and a plurality of colors are simultaneously projected, so that color separation is achieved. It is possible to perform processing with a black and white camera without the need for the, and an inexpensive device configuration can be achieved.

Further, by detecting the respective bright line positions from the image and calculating the color shift amount as the difference between the positions obtained by subtracting the projected position from the positions, the bright line positions having no temporal shift in the image input are obtained. Therefore, it is possible to calculate the color shift amount with high accuracy.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the appearance of bright lines in color shift measurement,

FIG. 2 is a block diagram of a color shift measuring device,

FIG. 3 is a flowchart showing a procedure for detecting a color misregistration amount in the vertical direction,

FIG. 4 is an explanatory diagram showing a window setting procedure for detecting a vertical bright line position.

[Explanation of symbols]

 21 ... Green bright line, 22 ... Red bright line, 23 ... Blue bright line.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Teruo Matsuo 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. Mobara factory

Claims (2)

[Claims] 1. The projection of a bright line, which is a measurement target in measuring the image quality of a color display device, is characterized in that the projection position is changed for each bright line of a different color and a plurality of colors are simultaneously projected at the same time. Color display device Color shift amount measuring method. 2. The color shift amount measuring method according to claim 1, wherein each bright line position is detected, and the color shift amount is calculated as a difference between the positions obtained by subtracting the projected position from the bright line positions.