JPS5842382A - Digital convergence device - Google Patents

Abstract

PURPOSE:To perform convergence adjustment quickly with good accuracy, by detecting an average position of a dot signal from a television camera and making the position of average value of each color coincident with each other. CONSTITUTION:At the first field, in picturing a green dot signal with a color signal switching device 27, the green dot signal is obtained for a television camera at the next field scanning and this is applied to an average value detection circuit 33 via a clip circuit 31 to detect the center position of a clipped pulse width and to set a green horizontal position counter 29 is set. Contents of the counters 28 and 29 are compared at a comparator 30 to shift a data reversible counter 13 so that the both are made coincident. That is, the data reversible counter 13 is shifted so that the average value of the red dot signal comes to the average value of the green dot signal, and the red dot signal is moved by changing the content of one frame memory 14.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a convergence circuit for a color television receiver, and an object thereof is to provide a digital convergence device that can be adjusted quickly and accurately.

In the shadow mask type color picture tube used in general color television receivers, color shift occurs because the radius of the shadow mask is larger than the distance from the center of deflection to the center of the shadow mask. . In addition, in projection-type color receivers that use three picture tubes that emit three primary colors to project enlarged images onto a screen, the angle of incidence of the picture tubes on the screen differs for each picture tube, so color misalignment occurs on the screen. arise. The superposition of these three primary colors, so-called convergence, is performed by creating a convergence correction waveform in an analog manner in synchronization with the horizontal and vertical scanning cycles, and adjusting this waveform. This method tends to have large convergence defects around the screen, and requires skill to adjust. For this reason, a method of digitally creating a convergence correction waveform has been proposed as a method of performing more accurate convergence over the entire screen.

This digital convergence method projects a convergence correction pattern such as a dot signal on the screen, then digitally writes the convergence correction amount data for each point in one frame memory, and then scans this data horizontally and vertically. It is read out in synchronization with the scanning signal, performs D, 4 conversion, and creates a convergence correction waveform.

Before explaining the present invention, a digital convergence device using an image sensor such as a camera will be described below with reference to FIGS. 1, 2, and 3.

First, as shown in Figure 1, on the screen, for example, 7 horizontal lines,
Five columns of dot signals are projected in the vertical direction.

The point where this dot signal is displayed is the convergence adjustment point, and it is intended to match the convergence coil at this point. FIG. 2 shows a conceptual diagram of digital convergence using a conventional television camera. In Figure 2, 1 is a projection type picture tube, 2 is a projection lens, '#3
is the screen, 4 is the deflection coil, and 6 is the convergence coil.

Here, 6 is a normal deflection circuit that scans the electron beam in the horizontal and vertical directions. The video circuit 7 performs the same operation as that of a normal receiver, but when adjusting convergence, it displays the dot signal created by the digital convergence device 8. In Figure 2, the projection type picture tube is 1
It only shows books, but on original color receivers, red, green,
Three picture tubes on the back are used. In this conventional example, a method of adjusting convergence by superimposing red and blue on green will be explained as an example. In the conventional device, the convergence shift of the dot signal 3 at the convergence adjustment point projected on the screen 3 is detected by a television camera 9 synchronized with the deflection circuit 6, and the signal is used to control the digital convergence device 8. This automatically adjusts convergence by changing the amount of correction. 1o is a convergence output circuit that amplifies the current of the signal from the digital convergence device and supplies it to the convergence coil 6.

FIG. 3 shows the configuration of a conventional digital convergence device. The operation shown in FIG. 3 will be explained using FIG. 4.

First, the case where the digital convergence adjustment is performed visually before the digital convergence adjustment using the television camera 9 will be described with the changeover switch 26 in FIG. 3 set to the C side.

First, an arbitrary point to be adjusted, for example, point B in FIG. 4, is designated on the control panel 11 in FIG. 3 and set in the write address counter 12.

Next, while looking at the screen, input the data of the color you want to adjust (red in the case of FIG.
Write data to. The data reversible counter 13 is a write address counter 12 and a read address counter 1.
The contents of 5 are compared by a comparator 16, and when they match, the data is written to the 1-frame memory 14. Also,
The multiplexer 17 switches between writing and reading. When it is desired to increase the total amount of convergence correction, the data written to the frame memory 14 is made thicker, and when it is desired to decrease the amount of correction, the data is made smaller and data for all adjustment points are written.

Next, to read data, the read address counter 16 is moved in synchronization with the deflection of the television receiver, and the contents of the one frame memory 4 are sequentially read out.

Basically, the read data is converted into an analog signal by a V MU converter, current is amplified through a low-pass filter 9, and a correction current is sent to the convergence coil. However, since the one-frame memory 14 only has data for locations corresponding to adjustment points, it is necessary to perform interpolation for each scanning line with respect to adjustment points in the vertical direction. Therefore, for example, the first column data is set in the 1H register 2o, the subtracter 21 subtracts the next second column data, and the result is multiplied by the coefficient preliminarily written in the coefficient ROM 22. The unit 23 multiplies by \ to approximately obtain the change for each scanning line.

This change and the original data are added to the adder 24 for interpolation, and the D/A converter 18. Convergence is performed through the low-pass filter 19.

The dot generator 26 generates a dot signal indicating the key 1 position of convergence.

Adjust other colors in the same way. Generally, adjustment in four directions is required to overlap the three primary colors at one point, and an actual digital convergence device is made up of four circuits as shown in FIG.

When adjusting visually as described above, it is necessary to perform the adjustment 7×6×4 times, that is, 140 times, at the adjustment points shown in FIG. 1, which has the drawback of being very time-consuming. Therefore,
There is a system in which the changeover switch 26 in FIG. 3 is switched to the D side, and the convergence adjustment, which has been adjusted visually up to now, is automatically adjusted using the camera 9.

Next, the operation of convergence adjustment using a camera will be explained using FIG. 4.

FIG. 4a shows the entire screen, and a focus signal is displayed as a signal for convergence adjustment. Here, the adjustment point B is enlarged with the television camera 9 so that an image as shown in FIG. 4 can be obtained. The television camera 9 may be of monochrome or color type. For the sake of clarity, the explanation will be made using a black and white camera, and the blue dot signal is omitted from FIG. 4, and the explanation will be given using red and green dot signals as an example. First, an arbitrary point at which convergence adjustment is to be performed, for example, point B in FIG. Next, point the television camera 9 at the point specified on the control panel and set it so that an image as shown in FIG. 4 is obtained. Next, during the first field scan, a green dot signal is displayed by the color signal switch 27. Then, TV camera 9 shows the fourth
A dot signal as shown in Figure C is obtained during the next field scan. Clock pulses are counted at the peak position of this signal, a green horizontal position counter 28 is set, and the horizontal position within the screen of the television camera 9 is measured in place of time. Next, when a red dot signal is displayed by the color signal switch 27, the television camera 9 obtains a dot signal as shown in FIG. 4d in the next field. At the peak value of this red dot signal, the red horizontal position counter 2
Set 9. Then, the comparator 30 compares the contents of the green horizontal position counter 28 and the red water position counter 29, and moves the data reversible counter 13 so that they match. That is, move the data reversible counter 13 so that the peak value t2 of the red dot signal comes to the peak value t1 of the green dot signal, change the contents of the 1-frame memory 14, and move the red dot signal up to FIG. 4B'. Bring. In this way, horizontal adjustment is performed. Next, in the same way as the horizontal direction, for vertical convergence, we measured the time from the vertical synchronization signal, detected the peak value position of the green and red dot signals, and found it at point B' in Figure 4. Match the red dot signal with the green dot signal at point B. In this case, another circuit would be required, constructed similarly to the portion of FIG. The above operation is also performed for the blue dot signal to match the green and blue dot signals.

The automatic digital convergence device using a television camera described above detects the peak position of the dot signal from the television camera and aligns the peak position with the peak position of the green dot signal as a means of combining the dot signals of each color. , was performing convergence adjustment.

FIG. 6a shows the dot signal from the digital convergence device of FIG. This dot signal as shown in FIG. 6a is added to the video circuit 7 in FIG.
A dot signal is displayed on the screen.

When the dot signal projected on the screen 3 is detected by the television camera 9, it has waveforms as shown in FIGS. 5d and 5c. The ideal detection signal of the television camera 9 has the waveform shown in FIG. 6a, but the initial characteristics of the electrical circuit (video circuit),
Depending on the characteristics of the optical system (CRT, lens, screen) and the sensitivity of the television camera 9, as shown in Figure 6 d and c,
The pulse width becomes wider, resulting in a waveform with lower frequency characteristics.

Therefore, the waveform whose peak position should originally be at the position Pl is shifted by J due to the above transmission system characteristics.
The waveform of C is shifted by 3. Therefore, when adjusting the convergence by detecting the peak position of the dot signal from the TV camera as a means of matching the dot signals of each color, the transmission system characteristics differ depending on each color, and the peak position of the dot signal of each color shifts. Even if the peak positions of the signals were matched for each color, the convergence did not match accurately.

Therefore, the present invention solves this problem by detecting the average value position of the dot signals from a television camera and matching the average value positions of each color as means for combining the dot signals of each color.

An embodiment of the present invention will be described with reference to FIGS. 6 and 7. In FIG. 6, parts that operate in the same way as in FIG. 3 are designated by the same numbers, and their explanations will be omitted.

A feature of the present invention is that, as a means of combining the dot signals of each color, the dot signal from the television camera is clipped at a certain amplitude level, and the center position of the pulse width of this signal is detected (
(hereinafter referred to as average position detection), and the correction amount of the digital convergence device is changed to automatically perform convergence adjustment so that this average position matches each color.

The operation of the embodiment shown in FIG. 6 will be explained using FIG. 7.

In FIG. 6, a line average position detection circuit 36 and an optical average position detection circuit 36 are provided for the purpose of the present invention and detect the average position of dot signals. When a green dot signal is projected by the color signal switch 27 during the first field, the television camera 9 obtains a video signal as shown in FIG. 7g during the next field scan. This green dot signal is applied to the clipping circuit 31, and clipped at the Vt (mac level) as shown in Fig. 7.This clipped signal is applied to the average value detection circuit, as shown in Fig. 7g. The center position of the clipped pulse width is detected and processed into the green horizontal position counter 28.The green horizontal position counter 28, which counts clock pulses at this center position, is set and the screen of the television camera 9 is set. Next, when the color signal switch 27 projects a red dot signal, the television camera 9 obtains a video signal as shown in FIG. 7d during the next field. Similarly, this red dot signal is also connected to the clip circuit 3.
2, as shown in Fig. 7g, the clipped signal is clipped at V2 (macro level).This clipped signal is applied to the average value detection circuit 34, and the clipped pulse width is calculated as shown in Fig. 7f. The center position is detected and added to the red water position counter.At this center position, the red horizontal position counter 29 is set.Then, the comparator 3o sets the green horizontal position counter 28 and the red horizontal position counter 29. The data reversible counter 13 is moved so that the contents of tg and tg are compared, and the data reversible counter 13 is moved so that the two match.In other words, the data reversible counter 13 is moved so that the average value of the red dot signal becomes equal to the average value tg of the green dot signal.

Then, as shown in FIG. 7g, the contents of the one-frame memory 14 are changed to move the red dot signal.

At this time, if we detect the peak position of the dot signal as in the past, we will see Figure 7! L,! :(Since the peak positions of the green and red dot signals shown in Figure 1 are both electric, the dot signals projected on the screen are as shown in Figure 7, where the red and green dot signals are shifted by the seedling. This results in poor convergence accuracy.

However, when the average position detection of the present invention is performed, the dot signals displayed on the screen match the center of the red dot signal with the center of the green dot signal, as shown in FIG. 7g.
Improves convergence accuracy. In this way, horizontal adjustment is performed. Next, for vertical convergence, similarly to the horizontal direction, the time from the vertical synchronizing signal is measured, and the average position of the green and red dot signals is detected to match the red dot signal with the green dot signal. In this case, the sixth
A separate circuit configured similar to the part shown is required. The above operation is also performed for the blue dot signal, and the green and blue dot signals are matched to adjust the convergence of the entire screen.

Further, FIG. 8 will be used to explain the average position detection circuit in detail. FIG. 8 shows the specific circuit configuration and waveforms of the average position detection power circuit.

A video signal as shown in FIG. 8 is obtained from the television camera. Adding this signal to the flip circuit 31, FIG.
As shown in v3 [McLevel is used. This clipped signal is supplied to the differentiation circuit 36 in the average value detection circuit 33 and differentiated to obtain a differential signal as shown in FIG. 8d.

This differential waveform is supplied to the calculation circuit 36, and calculation is performed using the positive polarity differential waveform P1 and the negative polarity differential waveform &.
[As shown, the average position is detected by detecting the center position waves of Pl and P2. Also, 1 frame memory 14
The reading of the correction amount written in is the same as in the conventional example, so the explanation will be omitted. Furthermore, 1 frame memory 14
It is necessary to read out according to the screen, so
This is done by a clock synchronized with the horizontal and vertical deflections.

As is clear from the above description, the present invention clips the dot signal from a television camera at a certain amplitude level and detects the center position of the pulse width of this signal (average position detection) and
The correction amount of the digital convergence device is changed so that this average position matches each color, and convergence adjustment is automatically performed. Therefore, the dot signals from the television camera reflect various characteristics of the electrical circuit (video circuit).

Characteristics of optical systems (CRT/lens, screen).

) and the sensitivity of the television camera, it is possible to eliminate the decrease in convergence accuracy due to pulse width changes and frequency characteristic deterioration, and to perform quick and accurate convergence adjustment.

[Brief explanation of the drawing]

Fig. 1 is an illustrative pattern diagram of a conventional digital convergence device for a color television receiver, Fig. 2 is a block diagram of a conventional digital convergence device using a television camera, and Fig. 3 is a conventional pattern diagram. 4 and 5 are pattern diagrams and waveform diagrams for explaining the conventional device, and FIG. 6 is a specific block diagram of the digital convergence device according to an embodiment of the present invention. 7 are waveform diagrams and pattern diagrams for explaining the present invention, and FIG. 8 is a block diagram and waveform diagram for explaining the present invention. 9...TV camera, 11...Control panel, 12...Writing address counter, 13...Data reversible counter, 14...
... 1 frame memory, 15 ... Read address counter, 16 ... Comparator, 17 ...
...Multiplexer, 18...D/"&exchange'?S, 19...Low pass filter, 20...
・1H register, 21...Subtractor, 22...
... Coefficient ROM, 23 ... Multiplier, 24
... Adder, 25 ... Dot generator,
26...Selector switch, 27...Color signal switch, 28...Green horizontal position counter, 29
・・・・・・Seishui position counter, 30・・・Comparator, 31, 32・・・Clip, 33, 34・
...Average value detector. Name of agent: Patent attorney Toshio Nakao and 1 other person17
Iil Figure 4 Figure 5 Figure 7 Figure 8

Claims (1)

[Claims] means for generating a plurality of convergence adjustment points in the horizontal and vertical directions on the screen of a color television receiver; an imaging means for enlarging and detecting a part of the screen including the convergence adjustment points; and each color component from the imaging means. means for clipping an output signal corresponding to the clipped output signal, means for detecting a center position of a pulse width of the clipped output signal, and a center position of the pulse width coincides between each component according to an output of the center position detection means. A means for correcting convergence deviation, a storage means for storing a correction signal from the convergence correction means as a digital signal, and a means for reading out the signal stored in the storage means and supplying it to the convergence coil are provided. A digital convergence device characterized by correcting.