JPH0750936B2 - Digital convergence device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for correcting the convergence of a color television receiver, which can be adjusted with high accuracy and is sufficiently compatible with those having different input sync signal frequencies. It relates to a possible digital convergence device.

Configuration of Conventional Example and its Problems Generally, in a color television receiver, there are three types of red, green, and blue.
An image is created by synthesizing colors on the fluorescent surface or on a screen to which the color has been applied. In this case, accurate alignment of the three colors, that is, convergence adjustment is an important issue affecting image quality.

Here, the deviation of the convergence will be described by taking an administration type color television receiver as an example.

In FIG. 1, reference numeral 1 denotes a projection screen for displaying an image, and 2, 3, 4 are projection type cathode ray tubes equipped with optical lenses for forming the image obtained on the fluorescent surface on the projection screen 1, respectively. Images of three colors, red, green, and blue, are obtained on the fluorescent surface. As shown in FIG. 1, when these picture tubes are arranged in the horizontal direction, the projection angles with respect to the projection screen 1 are different from each other, so that the projected raster has a positional deviation as shown in FIG. 2 for each color. . In FIG. 2, the solid line 3l is the projection raster of the green light by the picture tube 3, the shaded line 4l is the projection raster of the blue light by the picture tube 4, and the dashed-dotted line 2l.
Shows a projection raster of the red light by the picture tube 2.

To correct this misalignment, use projection type cathode ray tubes 2, 3, and 4.
In addition to the main deflection yoke, a convergence adjusting coil is provided, the sawtooth wave current in the horizontal scanning period is amplitude-modulated in the vertical period, and the amplitude can be adjusted independently for each color.

However, this amount of color misregistration is due to variations in the mounting position of each picture tube, variations in the configuration of the optical lens system,
Since the projection screen position changes due to fluctuations and the like, it is not possible to perform highly accurate convergence adjustment by simply combining the sawtooth wave current and the parabolic current.

As a method for realizing such convergence adjustment, a convergence circuit having a digital correction waveform forming unit is considered.

The conventional digital convergence device will be described in detail with reference to FIG.

Horizontal and vertical cycle pulses synchronized with the deflection current cycle are applied as synchronization signals, and the read address control unit 5 is driven thereby. The crosshatch pattern generator 6 is driven by using the pulse from the read address control unit 5 to project the crosshatch pattern on the projection screen. FIG. 4 shows a crosshatch pattern. On the other hand, the address key of the control panel 12 is used to specify a cross point (for example, FIG. 4A) at a position where convergence correction is required, and the position address is set in the write address control unit 8. Next, the correction amount is written in the one-frame memory 10 through the data reversible counter 11 while looking at the screen with the data write key of the color to be corrected, for example, the red data write key provided on the control panel 12. Normally, switching to the 1-frame memory is controlled by the multiplexer 9 so that the writing is performed in the blanking period of the video signal. Therefore, reading is not impaired. The same operation is performed at each adjustment point as described above. Next, the reading of the 1-frame memory 10 is performed by the read address control unit 5 at the cross position of each crosshatch on the screen, and the vertical interposition is performed via the register 18 driven by the read address control unit 5. The processing unit 13 performs a correction amount process in the vertical direction between the cross hatches.

Next, the operation of this correction process will be described with reference to FIGS.

The correction amount of each scanning line between points A and B or between points C and D shown in FIG. 4 can be obtained from (A−B) K + A or (C−D) K + C. Here, K represents a value obtained by linear approximation and is written in the ROM in advance. Therefore K is
It is clear that it can be obtained from the number N of scanning lines between points A and B. The number N of scanning lines is obtained from the number M of scanning lines in one field and the number of horizontal lines in the crosshatch. Next, the correction amount process between points A and B in FIG. 4 will be described with reference to FIG. The correction amounts at points A and B read from the one-frame memory 10 by the read address control unit 5 are registered in the registers 1 and 18 and the registers 2 and 19. The output signals of registers 1, 2, 18 and 19 are subtractor 20
And is multiplied by the coefficient for each scanning line from the coefficient generator 21 to obtain (AB) K, and the adder 23 outputs (AB) K.
+ A is sent out. In this way, the correction amount of the scanning line for which the correction amount is not stored is obtained. Next, the output signal is converted into an analog quantity by the D / A converter 14 in FIG. Next, the correction amount in the horizontal direction is smoothed through a reduction pass filter (LPF) 15, which is added to the output amplification section 16 to supply a correction current to the convergence coil 17. Convergence adjustment at each adjustment point is performed as described above.

However, in the conventional digital convergence device, when the sync signals of the horizontal and vertical sync pulses are different,
In order to smooth the number of scanning lines between the adjustment points of the vertical insertion processing unit 13 shown in FIG. 3, the value of the coefficient generator 21 shown in FIG. 5, various address signals and the correction amount in the horizontal direction. LPF
If the cutoff frequency of is not changed, the cross points of the crosshatch pattern displayed on the entire screen change, and there is a problem that the convergence adjustment cannot be performed accurately.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a digital convergence device which performs accurate convergence adjustment even for input sync signals having different frequencies.

According to the present invention, means for digitally storing a convergence correction amount for each adjustment point, means for detecting a horizontal scanning frequency from a synchronization signal input to a receiver, and a storage element of the storage element based on the detected signal. Based on the means for controlling the address and reading the amount of convergence correction corresponding to the horizontal scanning frequency, the means for setting the number of scanning lines between adjustment points in the vertical direction by the detected signal, and the number of scanning lines between the adjustment points. By controlling coefficient value setting means for setting a coefficient value for each scanning line, the convergence correction amount for each scanning line between the adjustment points in the vertical direction is approximated from the difference between the correction amounts of the upper and lower adjustment points and the coefficient value. A vertical adjustment point processing means to be obtained by
Low-pass filter means for smoothing data in the horizontal direction of the correction data processed between the vertical adjustment points; and control means for controlling the cut-off frequency of the low-pass filter according to the detected signal. It is a digital convergence device equipped with, by controlling the number of scanning lines between the storage element address and adjustment points, the coefficient value for each scanning line and the cutoff frequency of the LPF according to the horizontal scanning frequency of the input, It is possible to perform accurate convergence adjustment even for those having different horizontal scanning frequencies.

Description of Embodiments FIG. 6 is a block diagram of a digital convergence device according to a first embodiment of the present invention. In FIG. 6, the same operations as those in FIG. To do.

In FIG. 6, 26 is a horizontal scanning frequency detection unit, 27 is an adjustment point number setting unit, 28 is a coefficient setting unit, 29 is a vertical adjustment point processing unit, 30 is an LPF, A horizontal scanning frequency detecting unit 26 for detecting a horizontal scanning frequency and a horizontal scanning frequency detecting unit 26 for detecting a horizontal scanning frequency, and an adjustment point number setting unit 27 and a coefficient setting unit for setting the number of adjustment points in the vertical direction and the coefficient thereof according to the detected signal. The unit 28 and the vertical adjustment point processing unit 29 and the horizontal adjustment point obtained by calculating the convergence correction amount between the adjustment points from the difference between the correction amounts of the upper and lower adjustment points and the set number of adjustment points and the coefficient. It is for smoothing the correction amount, and is composed of an LPF 30 whose cutoff frequency can be controlled by the detected signal.

The operation of the digital convergence device of this embodiment constructed as above will be described below. The horizontal sync signal synchronized with the deflection current cycle is the horizontal scanning frequency detector.
Added to 26. The horizontal scanning frequency detection unit 26 is configured by a counter or the like, detects the horizontal scanning frequency, and is supplied to the adjustment point number setting unit 27, the coefficient setting unit 28, the LPF 30, the write address control unit 8, and the read address control unit 5. . The write address control unit 8 and the read address control unit 5 create an address signal corresponding to the horizontal scanning frequency based on the signal from the horizontal scanning frequency detecting unit 26. The adjustment point number setting unit 27 and the coefficient setting unit 28 are set by a signal from the horizontal scanning frequency detection unit 26 from among several kinds of adjustment point number data and coefficient data which have been written in advance. Adjustment point interval number data from the adjustment point interval number setting unit 27,
The coefficient data from the coefficient setting unit 28 is supplied to the vertical direction adjustment point processing unit 29. The operation and configuration of the vertical adjustment point processing unit 29 is the same as that of the conventional example shown in FIG. 5, and the convergence correction amount between the adjustment points is set to the difference between the correction amounts of the upper and lower adjustment points and the set adjustment point. From the interval data and coefficient data,
The correction amount for each scanning line between the adjustment points is calculated. The correction amount corresponding to each horizontal scanning frequency is smoothed by an LPF 30 such as an active filter whose cutoff frequency can be controlled by a signal from the horizontal scanning frequency detecting unit 26.

Next, reading and writing of the one-frame memory 10 are performed in the same manner as in the conventional case, and therefore the description thereof is omitted. In this embodiment, the case of performing the vertical adjustment point-to-point processing corresponding to the horizontal scanning frequency has been described, but the processing may be performed corresponding to the number of scanning lines.

Further, in the present embodiment, the case of performing the adjustment point number data and the coefficient data written in advance has been described, but the vertical direction adjustment point processing may be performed by automatically calculating from the scanning frequency and the number of scanning lines.

In addition, although the projection type color image receiver is described in this embodiment for easy understanding, it goes without saying that it is also effective for a shadow mask type direct-view type image receiver.

As described above, according to the present embodiment, the horizontal scanning frequency is detected, and the number of scanning lines between the address signal in the horizontal direction and the adjustment points in the vertical direction and the coefficient value for calculation are set by this detection signal. A process of approximating the difference between the correction amounts of the upper and lower adjustment points by the setting signal and the coefficient value, and a cutoff frequency of the low-pass filter for smoothing the processed correction data in the horizontal direction. By controlling by the detection signal and generating the correction data, it is possible to continuously deal with the change of the scanning frequency, and it is possible to realize the highly accurate correction.

According to the digital convergence device of the present invention, display means for generating and displaying a plurality of convergence adjustment points in the horizontal and vertical directions on the screen of a color television receiver, and an adjustment among the plurality of adjustment points. Input means for inputting position information of a point to be performed; storage means for digitally storing a convergence correction amount for the adjustment point; detection means for detecting a horizontal scanning frequency from a synchronization signal input to the receiver; Reading means for controlling the address of the storage element by the detected signal to read the convergence correction amount corresponding to the horizontal scanning frequency, and setting means for setting the number of scanning lines between the adjustment points in the vertical direction by the detected signal. And coefficient value setting means for setting a coefficient value for each scanning line based on the number of scanning lines between adjustment points in the vertical direction. Vertical adjustment point processing means for calculating the convergence correction amount for each scanning line between the adjustment points and the difference between the correction values of the upper and lower adjustment points and the coefficient value, and the vertical adjustment point processing. A low pass filter means for smoothing the corrected data in the horizontal direction, and a control means for controlling the cutoff frequency of the low pass filter according to the detected signal. The top can always display the same number of adjustment points. Therefore, according to the present invention, the adjustment points on the screen are not widened, and the adjustment can be performed accurately. Further, by having a lot of contents of the semiconductor elements of the adjustment point number setting unit and the coefficient setting unit, even for the signal sources having different scanning frequencies, the optimum correction waveform can be continuously obtained even if the scanning frequencies change. Since it can be created, it is possible to realize highly accurate correction for multi-scan that can correspond to any signal source, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing the principle of a projection type color television receiver, FIG. 2 is a diagram for explaining the convergence deviation, and FIG. 3 is a block diagram of a conventional digital convergence device, FIGS. FIG. 5 is a diagram for explaining the operation of the conventional device, and FIG. 6 is a block diagram of the digital convergence device in one embodiment of the present invention. 26 ... Horizontal scanning frequency detection unit, 27 ... Adjustment point number setting unit, 28 ... Coefficient setting unit, 29 ... Vertical adjustment point processing unit, 30 ... LPF, 8 ... Write address control unit, 5 ...
… Read address controller, 10 …… 1 frame memory.

Claims (1)

[Claims] 1. A display means for generating and displaying a plurality of convergence adjustment points in the horizontal and vertical directions on the screen of a color television receiver, and position information of the points to be adjusted among the plurality of adjustment points. Input means for inputting, storage means for digitally storing a convergence correction amount for the adjustment point, detection means for detecting a horizontal scanning frequency from a synchronization signal input to the receiver, and storage by the detected signal. Read-out means for controlling the address of the element and reading out the convergence correction amount corresponding to the horizontal scanning frequency, setting means for setting the number of scanning lines between adjustment points in the vertical direction by the detected signal, and adjustment in the vertical direction Convergence for each scanning line between the adjustment points in the vertical direction is controlled by controlling coefficient value setting means for setting a coefficient value for each scanning line from the number of scanning lines between points. The correction amount difference between the upper and lower adjustment points and the vertical adjustment point processing means obtained by approximate calculation from the coefficient value, and the digital correction data processed between the vertical adjustment points are converted into analog signals. Converting means for converting; low-pass filter means for smoothing data in the horizontal direction from the analog signal from the converting means; and controlling means for controlling the cut-off frequency of the low-pass filter according to the detected signal. And a digital convergence device driven by continuous correction waveforms from the control means.