JPH0622348A - Color cathode ray tube convergence measurement instrument - Google Patents

Abstract

PURPOSE:To accurately measure the convergence quantity and to reduce the manufacture cost. CONSTITUTION:A signal generator 1 and a cathode ray tube drive power supply 2 are used to display a convergence measurement pattern in three red, green, blue color dots or lines on a screen of a color cathode ray tube 3 so as to provide a positional phase difference without being overlapped with each other. Then a white/black television camera 4 picks up a convergence measurement pattern and a white/black picture processing unit 5 calculates a convergence quantity from a video signal of the television camera 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a red color cathode ray tube,
The present invention relates to a color cathode ray tube convergence measuring device that measures the amount of convergence indicating the degree of concentration of electron beams of three colors, green and blue, on a screen.

[0002]

2. Description of the Related Art In a conventional apparatus for automatically measuring the amount of convergence of a color cathode ray tube (Japanese Patent Laid-Open No. 61-2111935), a convergence measuring pattern of each color is sequentially emitted by controlling an electron gun driving circuit of three colors. Then, the convergence measurement pattern is imaged by using the monochrome TV camera, and the position of the convergence measurement pattern of each color is calculated from the video signal of the convergence measurement pattern by the monochrome image processing unit to obtain the convergence amount. In addition, the three colors of the convergence measurement pattern are simultaneously emitted, the colors are separated by the optical filter, the convergence measurement patterns that have been color-separated are sequentially picked up by the black and white television camera, and the convergence measurement pattern is made by the black and white image processing unit. The position of the convergence measurement pattern of each color is calculated from the image signal of 1 to obtain the amount of convergence.

[0003]

In these color cathode ray tube convergence amount measuring devices, since the convergence measuring pattern is time-sequentially imaged and image-processed, the position and shape of the convergence measuring pattern are temporal. When they change to, all of them affect the measured value of the convergence amount as a measurement error. That is, when the cathode ray tube drive circuit receives noise, when the contact resistance of the connector connecting the deflection yoke and the deflection amplifier is unstable, or when the voltage fluctuation rate of the high voltage power source for the anode is large, , The position and shape of the convergence measurement pattern are changed and displayed on the screen of the color cathode ray tube, and this variation causes a measurement error. Therefore, the amount of convergence cannot be accurately measured.

As a countermeasure against this, a white pattern obtained by simultaneously emitting three-color convergence measurement patterns on the screen of the color cathode-ray tube is projected, and the three-color convergence measurement patterns are simultaneously picked up by a single-plate or three-plate color TV camera. However, it is conceivable that the color image processing unit simultaneously processes three colors. However, when a single-panel color TV camera is used, the single-panel color TV camera has low characteristics such as color resolution, resolution, and sensitivity, so the amount of convergence cannot be accurately measured, and the color image processing unit is not used. However, it is more expensive than the black and white image processing unit, resulting in higher manufacturing cost. Also,
When using a three-panel color TV camera with excellent characteristics, the amount of convergence can be accurately measured, but the three-plate color TV camera is large and expensive, and the color image processing unit is also expensive. From
Manufacturing cost is high.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a color cathode ray tube convergence measuring device which can accurately measure the amount of convergence and which is inexpensive to manufacture. To do.

[0006]

To achieve this object, according to the present invention, dots of three colors of red, green and blue are provided which have a positional phase difference so that they do not overlap each other on the screen of a color cathode ray tube. A signal generator and a cathode ray tube drive power source that project a convergence measurement pattern of the line,
A black and white television camera for picking up the convergence measurement pattern and a black and white image processing unit for calculating the amount of convergence from the video signal of the black and white television camera are provided.

In this case, the black-and-white image processing unit calculates the maximum luminance value and the luminance center of gravity of the three-color dots or the three-color lines from the video signal, and calculates the three-color dots or the three-color dots. The emission color of the three-color dot or the three-color line is obtained from the relationship between the difference in the maximum luminance value of the line and the positional phase difference, and the luminance center of gravity of the three-color dot or the three-color line is calculated. It is preferable to use one that calculates the amount of convergence from the position and the positional phase difference.

[0008]

In this color cathode ray tube convergence measuring apparatus, since the three color dots or the three color lines of the convergence measuring pattern are simultaneously picked up and image-processed, the position or shape of the convergence measuring pattern changes with time. As a result, even if an inexpensive black-and-white color TV camera or black-and-white image processing unit is used without affecting the measurement value of the convergence amount,
3 color dots or 3 in the pattern for convergence measurement
Capturing and image processing can be performed by distinguishing color lines.

[0009]

1 is a block diagram showing the configuration of a color cathode ray tube convergence measuring apparatus according to the present invention. In this color cathode ray tube convergence measuring device, the signal of the convergence measuring pattern of the three color dots or the three color lines sent from the signal generator 1 is displayed on the screen of the color cathode ray tube 3 by the cathode ray tube drive power source 2. Is projected as. This convergence measurement pattern is picked up by a monochrome television camera 4 arranged in front of the surface of the color cathode ray tube 3, and its video signal is composed of an analog-digital converter 5a, an image memory 5b, a central processing unit 5c, an interface 5d and the like. Black and white image processing unit 5
To enter.

FIG. 2 is a block diagram showing a configuration of a signal generator of the color cathode ray tube convergence measuring apparatus shown in FIG. As shown in the figure, inside the signal generator 1, a delay device 1b for delaying the pulsed video signal generated by the oscillator 1a is inserted in the green signal line and the blue signal line. A switch 1c is provided at the subsequent stage of the delay 1b, and selects the delay signal and the original signal, and then outputs the video signals Rout, Gout, and Bout via the buffer amplifier 1d. in this case,
A phase difference is provided in the dot or line video signals Rout, Gout, Bout, and red on the screen of the color cathode-ray tube 3
Images separated into three colors, green and blue, are displayed. In this embodiment, the green video signal Go is used with the red video signal Rout as a reference.
The delay time Trg is given to ut, and the delay time Trb is given to the blue video signal Bout. The relationship between the delay time Trg and the delay time Trb and the pulse repetition period Tc is based on the following equation in the horizontal scanning range.

[0011]

## EQU1 ## Trb = 2 × Trg Tc = Trg + Trb In this way, the video signals Rout, Go of the three colors of red, green and blue are obtained.
ut and Bout project a convergence measurement pattern of vertical lines of three colors as shown in FIG. 3 on the screen of the color cathode ray tube 3 by the cathode ray tube drive power source 2. Then, in order to obtain the resolution required for the convergence measurement, the black-and-white television camera 4 magnifies and images a measurement point of the convergence measurement pattern, for example, a region surrounded by a solid line.

FIG. 4 shows an image of the measurement area which is enlarged and picked up by the monochrome television camera 4 and stored in the image memory 5b of the monochrome image processing unit 5. Here, assuming that the widths of the red, green, and blue bright lines R, G, and B are Lw, and the maximum value of the convergence amount between the respective colors to be measured is Cm, the delay times Trg, Tr
The positional phase differences Lrg and Lrb generated on the screen of the color cathode ray tube 3 due to b are determined so as to satisfy the following equation.

[0013]

[Formula 2] Lrg (= Lrb / 2) >> Lw + Cm Specifically, when Lw = 0.5 mm and Cm = 1.5 mm, if Lrg = 5 mm, the field of view when the monochrome TV camera 4 captures an image. Is suitable for image processing.

Since the image shown in FIG. 4 includes only the luminance signal and does not include the hue signal, the monochrome television camera 4 shown in FIG.
The emission color of the phosphor is identified by utilizing the spectral sensitivity characteristic of. That is, when the red, green, and blue colors are combined and the brightness is balanced so as to be white, the spectral energy is as shown in FIG.
As shown in, all three colors show almost the same intensity. But,
The human eye has a high sensitivity to green as shown in the relative luminous efficiency characteristic, and feels that green is bright and blue and red are dark. The black-and-white TV camera 4 also normally gives characteristics close to the relative luminous efficiency. The camera sensitivity of the black-and-white TV camera 4 of the combination of the CCD solid-state image sensor and the infrared cut filter used in this embodiment is shown in FIG. It was the characteristic shown.

A monochrome measurement camera 4 having a camera sensitivity characteristic close to such a relative luminosity senses a pattern for convergence measurement, and an image processing window W is set for the image (FIG. 4) stored in the image memory 5b. By setting and adding the data of each pixel of the image memory 5b in the y-axis direction of FIG. 4, the brightness level histogram shown in FIG. 6 is obtained.
The size of the image processing window W is determined in consideration of competing factors of processing time and measurement accuracy.

When a threshold value Th is set for this histogram and the brightness level is binarized, if the threshold value Th is lowered from the maximum value, the camera sensitivity of the monochrome television camera 4 shown in FIG. From the relationship between and the spectral energies of the three colors red, green and blue, the presence of bright lines is first confirmed in green, which has a high brightness level. Next, when the threshold value Th is lowered to near the background noise, bright lines of all three colors are confirmed. At this time, as is clear from (Equation 1) and (Equation 2), the emission lines are lined up in repetition of green, red, blue, green, and red from the known green emission line to the negative side address, and from the known green emission line to the positive side address. The bright lines are lined up with repeating green blue red green blue red. From these bright line arrays, a set of red, green, and blue located at the center of the address of the image memory 5b is selected as a target for center position calculation.

The center position X of the bright line selected by the above procedure on the screen of the color cathode ray tube 3 is obtained by the following equation.

[0018]

[Equation 3]

Here, i represents the address in the x-axis direction of the histogram obtained by adding the data in the image processing window W of the image memory 5b in the y-axis direction, and B (i) is the luminance at the address i. Indicates the level. m indicates the leftmost address of the calculation target bright line, and n indicates the rightmost address. Kx is a coefficient for converting the number of pixels into the length of the color cathode ray tube 3 on the screen.

The reason why the maximum value of the brightness level B (x) is not the center of the bright line but the center of gravity of the brightness level B (x) is the center is shown in FIG. 6 by an envelope for convenience. ,
The actual brightness level histogram is shown in the color cathode ray tube 3.
This is because it is considered to be a set of discrete data due to the phosphor dot arrangement on the screen, and the measurement error increases when the maximum value of the brightness level B (x) is set to the center of the bright line.

When the center position of the red line is Xr, the center position of the green line is Xg, and the center position of the blue line is Xb, the center positions Xr, Xg, and Xb are the influences of the delay times Trg and Trb shown in FIG. That is, it is a value that includes the positional phase differences Lrg and Lrb on the screen of the color cathode ray tube 3.
It does not indicate the original amount of convergence. Red,
XR, XG, and XB are the original center positions of the green and blue bright lines.
Then, the center positions XR, XG, and XB are obtained by the following equation.

[0022]

XR = Xr XG = Xg-Lrg XB = Xb-Lrb Next, the convergence amount, for example, XG-XR, XB-
Calculate XG.

The values of the positional phase differences Lrg and Lrb are not constant, but differ depending on the size of the color cathode ray tube 3, the characteristics of the deflection circuit, the electrode voltage, that is, the tube type. Therefore, prior to the measurement of the amount of convergence, the switching device 1c is opened and closed to set the signal generator 1 to a green (or blue) monochromatic output condition, and the center of the bright line with and without the influence of the delay device 1b. A simple and accurate method is to measure the amount of movement of the position directly by the monochrome image processing unit 5 to obtain the positional phase difference Lrg (or Lrb) and store this.

The procedure described above is a method of measuring the horizontal convergence amount by the vertical line pattern. However, regarding the vertical convergence amount, a phase difference of three colors is given in the vertical direction by the horizontal line pattern. Can be achieved. However, in order to obtain vertical and horizontal two-dimensional data by the measurement using the line pattern, it is necessary to measure the vertical and horizontal two times.

FIG. 7 is a diagram showing an image of a dot pattern stored in the image memory of another color cathode ray tube convergence measuring apparatus according to the present invention. In this color cathode ray tube convergence measuring device, the signal generator 1 outputs a convergence measuring pattern of dots of three colors instead of a pattern of measuring convergence of lines of three colors. This convergence measurement pattern has the above-mentioned x
In addition to the positional phase differences Lrg and Lrb in the axial direction, the positional phase differences Mrg and Mrb in the y-axis direction are provided. The threshold value Th is set similarly to the processing of the convergence measurement pattern of the three color lines, and the brightness level is binarized. When the threshold value Th is lowered from the maximum value, the presence of bright spots is first confirmed in green, which has a high luminance level, from the relationship shown in FIG. Next, when the threshold value Th is lowered to near the background noise, bright spots of all three colors are confirmed.
The bright point at the negative address on both the x-axis and the y-axis is red with respect to the green bright point, and the bright point at the positive address on both the x-axis and the y-axis is blue. From the array of red, green, and blue luminescent spots, a set of red, green, and blue located at the center of the address of the image memory 5b is selected as the target of center position calculation, and x
The axial center positions XR, XG, and XB are given by (Equation 4),
The center positions YR, YG, and YB in the y-axis direction are calculated by the following equation.

[0026]

## EQU5 ## YR = Yr YG = Yg-Mrg YB = Yb-Mrb In such a color cathode ray tube convergence measuring device, a two-dimensional convergence amount can be obtained by a single measurement.

In the above embodiment, the delay device 1b is used.
Although the signal generator 1 having the above is used, a method of incorporating a personal computer as a signal generator and utilizing its drawing function to program a measurement pattern in the video RAM of the computer to output a video signal is simple.

[0028]

As described above, in the color cathode ray tube convergence measuring apparatus according to the present invention, even if the position or shape of the convergence measuring pattern changes with time, it affects the measured value of the convergence amount. Since it is possible to accurately measure the amount of convergence, and even if an inexpensive black-and-white color TV camera or black-and-white image processing unit is used, the three-color dots or three-color lines of the convergence measurement pattern can be divided. Since the imaging and the image processing can be performed separately, the manufacturing cost is low. As described above, the effect of the present invention is remarkable.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a color cathode ray tube convergence measuring device according to the present invention.

FIG. 2 is a block diagram showing a configuration of a signal generator of the color cathode ray tube convergence measuring device shown in FIG.

FIG. 3 is a schematic diagram showing a state in which a convergence measurement pattern is projected on the screen of the color cathode ray tube shown in FIG.

4 is a diagram showing an image of a line pattern stored in an image memory of the monochrome image processing unit shown in FIG.

FIG. 5 is a light emitting characteristic of the color cathode ray tube shown in FIG.
9 is a spectral characteristic curve diagram showing the sensitivity characteristic of the monochrome television camera shown in FIG.

6 is an operation explanatory diagram of the monochrome image processing unit shown in FIG. 1. FIG.

FIG. 7 is a diagram showing an image of a dot pattern stored in an image memory of another color cathode ray tube convergence measuring device according to the present invention.

[Explanation of Codes] 1 ... Signal generator 2 ... Cathode ray tube driving power source 3 ... Color cathode ray tube 4 ... Monochrome television camera 5 ... Monochrome image processing unit

Claims (1)

[Claims] 1. A signal generator and a cathode ray tube driving power source for projecting a convergence measurement pattern of red, green, and blue three-color dots or lines having positional phase differences so as not to overlap each other on the screen of the color cathode ray tube. And a black and white television camera that captures the convergence measurement pattern,
A cathode ray tube convergence measuring device, comprising: a monochrome image processing unit for calculating a convergence amount from a video signal of the monochrome television camera.