JPS5838995B2 - Comberzen Suirozure Kenchihouhou Oyobi Sonosouchi - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to convergence adjustment of a color picture tube,
The present invention relates to a convergence color shift detection method and apparatus for detecting convergence color shift.

[Background of the invention]

Conventionally, convergence color shift has been detected visually by an adjuster.

That is, the method uses an external adjustment signal, for example,
By applying a loss hatch pattern signal as shown in Japanese Patent No. 12410, a white lattice-like line composed of red, green, and blue is displayed on the screen 1 of the color picture tube to be inspected as shown in Fig. 1. Draw pattern 1a and check the color shift at that time, that is, the second
As shown in the figure, visually determine when the white line is separated into the three primary colors of red, green, and blue (to), and the color is no longer white, and adjust the convergence of the color picture tube to eliminate this color shift. is being carried out.

At this time, the amount of deviation is not constant at all locations on the screen of the color picture tube, and in general, it is not possible to make adjustments to completely eliminate the deviation at all locations.

Therefore, rather than making a complete adjustment in one place, adjustments are made in a way that makes the deviation less noticeable overall.

This requires the subjectivity of the adjuster, and it is difficult to make the convergence color shift adjustment uniform for all color picture tubes.

In addition, color matching is problematic due to misalignment of each phosphor, so a magnifying glass must be used if necessary.

In addition, all the parts to be adjusted are installed on the back of the color picture tube, so you can adjust the convergence color shift by reaching to the back of the color picture tube while looking at the screen to be inspected with a magnifying glass. However, the conventional convergence adjustment method described above has the disadvantage of extremely poor workability.

In order to eliminate such drawbacks, the applicant has proposed
No. 5210 has already been proposed.

This invention uses a black-and-white television camera to photograph monochromatic linear patterns of red, green, and blue, which are the constituent colors of a white line applied to a color television screen to be inspected from the outside as an adjustment signal, and to produce a composite television video signal. The video signals in any one horizontal scanning period in one field are extracted from the field, and the mutual positions of the red, green, and blue video signals in that scanning period are automatically measured by predetermined level comparison, and the color shift is digitally measured. It is designed to detect

However, through subsequent experiments, the present inventors found that the degree to which the human eye perceives color shifts is greater than the level detection of the above-mentioned application, and that It has been confirmed that it is most effective in terms of accuracy to set the position that indicates the peak value of the light amount of the linear pattern, rather than using the geometric center of a small area that is larger than the light amount as a reference.

Generally, it is clear that the current density distribution of the electron beam spot is approximately symmetrical on the left and right sides of a straight line passing through the peak value.

On the other hand, in a color picture tube, the light-emitting phosphors of each color are not arranged without gaps, but are arranged discretely with a predetermined regularity, as is well known.

Therefore, when detecting the center of the electron beam spot from the light emission state of such discretely arranged emitting phosphors,
The method based on the geometric center according to the invention of JP-A-49-40424 mentioned above has a problem with accuracy, and the accuracy of the width of one light-emitting phosphor (for example, 0.2 mW) or more is I can't take it.

This is because a considerable amount of error is included when identifying the small area that is the basis for calculating the geometric center.

That is, in the invention of JP-A-4940424, it is digitally determined whether or not a light-emitting phosphor located at the boundary of a region is emitting light, that is, whether or not the phosphor has a predetermined amount of light or more. The small area is determined only after
Even though the phosphor located at the boundary is slightly shining, if the amount of light is less than a predetermined amount of light, it is determined that it is not shining.

If digital judgment is involved when identifying the small area that is the basis for calculating the geometric center, there is a concern that the obtained geometric center will contain an error equal to the width of up to two phosphors, and the accuracy will be poor. This has the disadvantage that it cannot be placed under the width plate of a single phosphor.

[Purpose of the invention]

Therefore, an object of the present invention is to provide a color shift detection method and a detection device that further improves the convergence color shift detection accuracy.

[Summary of the invention]

As mentioned above, based on the confirmation result that the degree to which the human eye perceives color shift is most effective in terms of accuracy at the position where the peak value of the light intensity of the linear pattern is shown, the present invention By adjusting the distance between the color picture tube and the color picture tube, a video signal with a chevron waveform is extracted from the linear pattern of each color projected on the screen, and the time to the chevron waveform is calculated based on the horizontal synchronization signal. When measuring, the measurement is completed when the peak value of the image signal is detected, and the minute light amount of the phosphor near the boundary, which is concerned about being discarded in the above-mentioned Japanese Patent Application Laid-Open No. 49-40424, is also considered. The purpose is to realize highly accurate color shift detection by reflecting it in the above-mentioned chevron waveform.

[Embodiments of the invention]

The present invention will be specifically described below based on embodiments shown in the drawings.

The screen of the color picture tube to be inspected shall display a crosshatch, or lattice-like linear pattern, for each of the three primary colors, red (red), green 'G), and iB), as shown in Figure 2, for convergence adjustment. .

However, in order to simplify the explanation, the following explanation will be made assuming that a predetermined vertical line pattern is projected for each color on the color picture tube to be inspected, as shown in FIG.

A single vertical white line pattern like this is given to the color picture tube screen to be inspected, and the block configuration shown in Figure 4 is photographed using a black and white television camera so that the entire color picture tube screen to be inspected is included. At this time, the distance between the black and white television camera and the screen of the color picture tube to be inspected is arbitrarily adjusted in order to obtain a video signal having a chevron-shaped waveform from the linear pattern of each color.

Therefore, the video signal of a portion where color shift occurs, such as portion A in FIG. 3, becomes as shown in FIG. 6.

Figure 6 a, b, and c show the color picture tube screen with the three primary colors red (6).
This is a video signal waveform obtained by sequentially developing each of , green 0, and blue (B) one color at a time.

In places where color shift occurs in this way, the positions of the signal waveforms representing the line positions of the three primary colors, as shown in Figure 6 a, b, and c, become temporally shifted with respect to the horizontal synchronization signal. (tR+tG+tB).

Therefore, the amount of color shift can be determined by detecting this amount of time shift.

The present invention uses a video signal waveform as shown in FIG.
In order to find the position of a colored line on the color picture tube screen, the peak position of the waveform is used as the end signal of the time measurement, and the amount of color shift due to convergence is detected.

Figure 6a. The signal waveforms for each of b and c are obtained using a black and white TV camera to capture the difference between the colors being produced, so the signal amplitude levels etc. are different, and the waveforms of each color are different regardless of this level. You can compare locations.

Next, one embodiment of the convergence color shift detection device will be described based on FIGS. 4 and 5.

That is, the convergence color shift detection device has a screen in which each of the three primary colors red, green 0, and blue (B) is sequentially switched by a three primary color changeover switch 3, and a predetermined linear pattern is displayed using a signal from a pattern generator 2. A black and white television camera 4 and a camera controller 5 for photographing the screen by arbitrarily adjusting the distance between the color picture tube 1 to be inspected and the screen of the color picture tube 1 to be inspected, and the camera controller 5. An analog switch 7 for arbitrarily extracting only the detected portion of the video signal 15, a gate signal 17 given to the analog switch 7 to specify the detected portion, and a time measuring device 14 for measuring the waveform position. A detecting section arbitrarily specified signal generating circuit 6 which gives a stop signal 22, and a peak position detection circuit which determines the peak position of the signal waveform obtained as shown in FIGS. It consists of a circuit 13 and a time measuring device 14 for measuring the waveform position as time.

With the above configuration, the positions of each of the three primary colors (tR, tG, tG,
When the color picture tube 1 to be inspected is adjusted so that the values of tB) match, the convergence adjustment is completed.

The detecting unit arbitrary designated signal generating circuit 6 is a black and white television camera 4.
When the entire screen of the color picture tube 1 to be inspected is photographed using, for example, 525 scanning lines, the number of scanning lines to be used and the part of the waveform on that scanning line to be detected are set in advance, and the analog A gate signal 17 as shown in FIG. 14, a start signal 22 as shown in FIG. 7A is applied as a reference for the rising edge of the horizontal synchronizing signal 16 shown in FIG. 7A detected from the camera controller 5.

The peak position detection circuit 13 detects the peak position of waveforms as shown in FIG. It is composed of a comparison circuit 12.

Specifically, it is configured as shown in FIG.

That is, the terminal 23 is a terminal to which a video signal obtained through the analog switch 7 is applied.

The AC component extraction circuit 8 includes a capacitor C having one end connected to the terminal 23 and the other end connected to the base of the transistor Tr1.
1, the base of the transistor Tr1 and the direct current power supply +V
The variable resistor ■R1 is connected between the base of the transistor Tr1 and the negative DC power source −■, and the base is connected to the other end of the capacitor c1, and the collector is connected to the The transistor Tr1 is connected to a current power source +■ and has an emitter as an output terminal 24.

The attenuator 11 is formed of a variable resistor having an intermediate movable terminal, one end of the fixed terminal is connected to the emitter of the transistor Tr1, the other end of the fixed terminal is grounded, and the attenuated signal 20 is output from the intermediate movable terminal. This is what is output.

The peak hold circuit 9 has a positive side connected to the transistor Tr.
An operational amplifier 25 is connected to the output terminal 24 of the first operational amplifier 1, and the negative side is connected to the cathode side of the diode D2, and a diode D is connected with its cathode facing the output of the operational amplifier 25, and its anode is grounded.
1, a diode D2 connected with its anode facing the output of the operational amplifier 25, and a peak value holding capacitor C2 having one end connected to the cathode of the diode D2 and the other end grounded.

The buffer amplifier 10 has a gate connected to the cathode side of the diode D2, a drain connected to the direct current power supply +■,
A field effect transistor F whose source is connected to the base of the transistor Tr2, and a field effect transistor F whose base is connected to the base of the transistor Tr2.
A transistor T whose collector is connected to the direct current power supply +V and whose emitter is grounded via the resistor R2.
It is composed of r2.

The comparison circuit 12 has a positive side connected to the intermediate movable terminal of the attenuator 11 via a resistor R4, and a negative side connected to the buffer amplifier 10.
The peak position detection signal 21 is connected to the emitter of the transistor Tr2 via a resistor R3, and outputs a peak position detection signal 21.

With the above configuration, first, on the color picture tube 1 side to be inspected, a predetermined linear pattern is displayed on the screen using a signal from the pattern generator 2, as shown in FIG. 3 primary colors red (8
), green 0, and blue (B) are each displayed individually in sequence.

Next, on the imaging side, the black and white television camera 4 whose distance to the screen is adjusted takes an image while scanning the linear pattern of each color in the direction of the arrow shown in FIG. The controller 5 outputs a video signal 15R shown in FIG. 6A for the red linear pattern, a video signal 15G shown in FIG. 6S for the linear pattern, and a video signal 15G shown in FIG. 6 for the blue linear pattern. A video signal 15B shown in C is detected.

The detection section arbitrary designation signal generation circuit 6 presets the number of scanning lines to be used based on the vertical synchronization signal detected for each image capture screen from the camera controller 5, and also sets in advance the number of scanning lines to be used based on the horizontal synchronization signal. The gate signal 17 shown in FIG. 7C is applied to the analog switch 7 so as to set in advance which part of the video signal waveform on the scanning line is to be detected, and to draw the video signal in the required section.

Therefore, the analog switch 7 detects that the gate signal 17 is "1".
' is closed, and the video signal 18 output from the camera controller 5 for that section is input to the input terminal 2 of the peak position detection circuit 130.
3.

The AC component extraction circuit 8 of this peak position detection circuit 13 is
Extracting only the alternating current component of the video signal 18, that is, the component whose output fluctuates according to the linear pattern, using the capacitor C1;
It is amplified by transistor Tr1.

This amplified video signal is output from the emitter of the transistor Tr1, and the peak value of this video signal is held in the capacitor C2 of the peak hold circuit 9.

The peak value of this video signal is amplified by a buffer amplifier 10 and applied to one side of a comparator 12 as a peak value signal 19.

Further, the video signal output from the emitter of the transistor Tr1 is slightly attenuated by an attenuator 11, and this attenuated video signal 20 is applied to the + side of the comparator 12.

In other words, a minute voltage △V required for switching of the comparator 12 is required between the signal that maintains the peak value of the video signal input to the one side terminal of the comparator 12 and the video signal input to the + side terminal. Therefore, when the comparator 12 is switched, it is a short time after the peak value of the video signal.

However, even in this case, since the mutual relationship between the peak positions of the video signals obtained by the linear patterns between the respective colors is determined, the above-mentioned minute time difference hardly poses a problem.

Nevertheless, in order to eliminate the minute time difference, the comparator 12 attenuates the peak value of the video signal 20 by adjusting the attenuator 11 by the minute voltage ΔV required for switching, as shown in FIG. 8a. + of comparator 12 in the form of
It is applied to the side.

The number comparator 12 compares the peak value holding signal 19 of the video signal with the video signal 20 attenuated by the attenuator 11 as shown in FIG. A signal switched at the peak position, that is, a peak position detection signal 21 is detected.

Therefore, the time measuring device 14 starts from the rising edge of the start signal 22, which is generated by the detecting section arbitrary designation signal generating circuit 6 as shown in FIG. By measuring the time to the rising edge of the peak position detection signal 21 outputted by the comparator 12, the time to the peak position of the video signal obtained by the linear pattern of each color with the horizontal synchronization signal as a reference is determined. I can do it.

For example, a gate signal of "1" is formed from the rising edge of the start signal 22 to the rising edge of the peak position detection signal 21, the gate signal and a constant high frequency clock signal are ANDed by an AND gate, and the gate signal is By counting the peak position of the video signal, the peak position of the video signal can be determined.

Although the above embodiment described a linear pattern in the vertical direction, in order to capture a linear pattern in the horizontal direction, the black-and-white television camera is rotated 90 degrees to take an image, or two images are taken so that the scanning directions are 90 degrees different from each other. If a monochrome television camera is placed in front of the screen of the color picture tube 1 to be inspected, it is possible to detect color shift due to convergence by using the circuit configuration described above.

〔Effect of the invention〕

As explained above, the present invention is a method of photographing a TV screen to be inspected with a black-and-white TV camera, converting it into a video signal, and temporally comparing the peak positions of the video signal waveforms for each of the three primary colors. It is possible to make a quantitative judgment without any interference, and the inspection accuracy can be sufficiently satisfied.

In other words, the convergence can be determined by comparing the peak position of the video signal for the three primary color linear patterns from the point that is most visible to the eye, that is, the point where the light intensity is the strongest within the linear pattern mountain, which corresponds to the peak position of the video signal. Color shifts can be detected with high precision.

Further, according to the present invention, the configuration of the device can be extremely simplified compared to the conventional method, and furthermore, the inspection time and cost can be sufficiently reduced to practical use.

[Brief explanation of the drawing]

1 to 3 each show the screen of the color picture tube to be inspected, and FIG. 1 shows an adjusted state with no convergence color shift when a white grid-like linear pattern is applied.
FIG. 2 shows a state in which color shift occurs, and FIG. 3 shows a state in which a single vertical white line is provided as a pattern to cause convergence color shift. FIG. 4 is a block diagram showing an embodiment of the convergence color shift detection device of the present invention, FIG. 5 is a circuit diagram specifically showing the peak position detection circuit shown in FIG. 4, and FIG. A diagram showing the vertical line pattern shown in FIG. 3 and the waveform of a video signal captured by a black and white television camera shown in FIG. 4 for each color,
7 is a diagram showing the signal waveform output from the circuit shown in FIG. 4, and FIG. 8 is a signal waveform diagram for explaining the operating principle of the peak position detection circuit shown in FIGS. 4 and 5. be. 1...Color picture tube to be inspected, 2...Pattern generator, 3...3 primary color selection switch, 4...Black and white television camera, 5...・
... Camera controller, 6 ... Detection section arbitrary specified signal generation circuit, 7 ... Analog switch, 9 ...
... Peak hold circuit, 11 ... Attenuator, 12 ... Comparator, 13 ... Peak position detection circuit, 14 ... Time measuring device , 15, 18
...Video signal, C1, C2... Capacitor, Trl. Tr2...Transistor.

Claims (1)

[Scope of Claims] 1 Linear patterns of red, green, and blue colors are sequentially projected at the same position on the screen of a color picture tube to be inspected, and an image pickup device placed in front of the screen captures the linear patterns of each color. The pattern is scanned and imaged in the line width direction for a specific horizontal scanning period, each video signal is extracted from the linear pattern of each color, and the time to each of the above video signals is measured using the horizontal synchronization signal as a reference. In the convergence color shift detection method, the temporal deviation between the video signals of the color picture tube to be inspected is detected as convergence color shift of the color picture tube to be inspected, wherein the imaging device adjusts the distance between the imaging device and the screen. By doing this, a video signal having a chevron-shaped waveform is extracted from the linear pattern of each color displayed on the screen, and the peak position of each waveform of the video signal is set as the end position of the time measurement. A convergence color shift detection method characterized by: 2 Linear patterns of each color of red, green, and blue are sequentially projected at the same position on the screen of the color picture tube to be inspected, and the linear patterns of each color are projected in the width direction using an imaging device placed in front of the screen. Scan imaging for a specific horizontal scanning period to extract each video signal from the linear pattern of each color, measure the time to each video signal with the horizontal synchronization signal as a reference, and calculate the difference between these video signals of each color. In the convergence color shift detection device that detects temporal deviation as convergence color shift of the color picture tube to be inspected, the image pickup device is configured to display images on the screen by adjusting the distance between the imaging device and the screen. a holding circuit configured to extract a video signal having a chevron-shaped waveform from the linear pattern of each color, and holding a peak value of the video signal extracted from the imaging device; a comparison circuit that compares a peak value held in the circuit with a video signal extracted from the imaging device and derives a peak position signal when the level of the video signal is slightly lower than the peak value; at least a measuring means for measuring the time until the peak position signal derived from the comparator circuit based on the horizontal synchronization signal obtained when the imaging device scans, and measuring the time until the peak position signal is measured by the end of the time measurement. A convergence color shift detection device characterized by being configured to be used as a signal.