JPH045314B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a device for correcting the convergence of a color television receiver, which can be adjusted with high precision and is fully compatible with input synchronization signals having different frequencies. The present invention relates to a possible digital convergence device.

Conventional configuration and its problems Generally, in color television receivers, red,
Images are created by combining the three colors green and blue on a fluorescent surface or a projected screen.
In this case, accurately aligning the three colors, that is, convergence adjustment, becomes an important issue that affects image quality.

Here, the convergence shift will be explained using a projection type color television receiver as an example.

In FIG. 1, numeral 1 indicates a projection screen for projecting an image, and numerals 2, 3, and 4 are projection type cathode ray tubes each equipped with an optical lens for forming an image obtained on a fluorescent surface onto the projection screen 1. Three-color images of red, green, and blue are obtained on the fluorescent surface. As shown in FIG. 1, when these cathode ray tubes are arranged in the horizontal direction, the projection angles relative to the projection screen 1 are different, so that the projected rasters of each color are misaligned as shown in FIG. 2. In FIG. 2, a solid line 3l shows a raster projected by the cathode ray tube 3 for green light, a broken line 4l shows a raster projected by the cathode ray tube 4 for blue light, and a dash-dotted line 2l shows a raster projected by the cathode ray tube 2 for red light.

To correct this positional shift, a convergence adjustment coil is installed in the projection cathode ray tubes 2, 3, and 4 separately from the main deflection coil, and the sawtooth wave current in the horizontal scanning period is amplitude-modulated in the vertical period. The amplitude can be adjusted independently.

However, the amount of color shift changes due to variations in the mounting position of each cathode ray tube, variations in the configuration of the optical lens system, variations in the projection screen position, etc., so in order to perform highly accurate convergence adjustment, a simple sawtooth wave current or , which is not possible with a combination of parabolic currents.

As a method for realizing such convergence adjustment, a convergence circuit having a digital correction waveform forming section has been considered.

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

Horizontal and vertical period pulses synchronized with the deflection current period are added as synchronization signals, thereby driving the read address control section 5. The pulses from the read address control section 5 are used to drive the crosshatch pattern generator 6 to project a crosshatch pattern on the projection screen. Figure 2 shows a crosshatch pattern. On the other hand, using the address key on the control panel 12, a cross point (for example, A in FIG. 4) at a position requiring convergence correction is specified, and a position address is set in the write address control section 8. Next, use the data write key for the color you want to correct, for example, red, provided on the control panel 12, and while looking at the screen, write data into the 1 frame memory 1 through the data reversible counter 11.
Write the correction amount to 0. Normally, the multiplexer 9 performs switching control such that writing into the one-frame memory is performed during the blanking period of the video signal. Readout is therefore not impaired. Similar operations are performed at each adjustment point as described above. Next, the readout of the one frame memory 10 is performed by the readout address control unit 5 for the cross position of each crosshatch on the screen, and then through the register 18 driven by the readout control unit 5, At step 13, correction amount processing in the vertical scanning direction between crosshatches is performed. Next, the operation of this correction process will be explained with reference to FIGS. 4 and 5. Figure 4: The amount of correction for each scanning line between A and B or between C and D is (A-B)K+A
It can be obtained from the formula. Here, K indicates a value obtained by linear approximation and is written in the ROM.
Therefore, it is clear that K can be determined from the number N of scanning lines between A and B. Further, the number of scanning lines N is determined from the number of scanning lines M in one field and the number of horizontal lines in the crosshatch. Next, the correction amount processing between A and B in FIG. 4 will be explained with reference to FIG. The correction amounts of points A and B read out from the one-frame memory 10 by the read address control unit 5 are registered in registers 1 and 18 and registers 2 and 19. The output signals of registers 1 and 2 are subjected to the operation (A-B) by the subtracter 20, sent to the multiplier, multiplied by the coefficient for each scanning line to obtain (A-B)K, and then sent to the multiplier by the adder 23. (A-B) K+A is sent. In this way, the correction amount for the scanning line for which the correction amount is not stored is determined. Next, the output signal is sent to the D/A converter 14
Convert to analog quantity. Next, the current is applied to the output amplification circuit section 16 through the low-pass filter 15, and a correction current is supplied to the convergence coil 17. Convergence adjustment at each adjustment point is performed as described above.

However, in conventional digital convergence devices, when the synchronization signals of horizontal and vertical periodic pulses are different, for example, when the number of horizontal periodic pulses in one field becomes 300 or 400, vertical adjustment point-to-point processing is performed each time. Unless the number of scanning lines between the adjustment points in section 13 is changed and the value of the coefficient generator is not changed, the distance between the cross points of the crosshatch pattern displayed on the entire screen will become wider or shorter, making it impossible to accurately adjust the convergence. .

OBJECTS OF THE INVENTION An object of the present invention is to provide a digital convergence device that can automatically make the above changes and perform accurate convergence adjustment by detecting the frequency of an input synchronizing signal.

Structure of the Invention The present invention provides means for generating and displaying a plurality of convergence adjustment points in the horizontal and vertical directions on the screen of a color TV receiver, means for inputting position information of the adjustment points, and convergence correction for the adjustment points. means for digitally storing the amount of correction; means for reading out the stored correction amount; means for detecting the number of scanning lines for one field from a synchronization signal input to the receiver; means for setting the number of scanning lines between adjustment points; means for determining and storing coefficient values for each scanning line from the number of scanning lines between adjustment points; The digital convergence device is characterized in that it is provided with vertical adjustment point-to-vertical adjustment point processing means for calculating from the difference between the coefficient values and the coefficient values.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 6, parts that operate in the same way as in FIGS. 3 and 5 are designated by the same numbers and their explanations will be omitted. 6th
In the figure, 26 is a scanning line number detection section, 27 is an adjustment point interval number setting section, 28 is a coefficient calculation section, and 29 is a vertical adjustment point interval processing section, which are provided for the purpose of the present invention. The operation of this embodiment will be explained below.

Horizontal and vertical synchronization signals synchronized with the deflection current period are applied to the scanning line number detection section 26 of the present invention.
The scanning line number detection unit 26 is composed of a counter etc.
The number of scanning lines in one field is detected and added to the adjustment point interval number setting section 27. The adjustment point interval setting section 27 has 1
From the number M of scanning lines of the field and the number L of adjustment points in the vertical direction, the number N of scanning lines between N=M/L+1 adjustment points is determined and added to the coefficient calculating section 28. In addition to the write address control section 8 and the read address control section 5, the operation is switched every N addresses. The coefficient calculating unit 28 calculates a coefficient for each scanning line between adjustment points (a value that changes at a rate of 1/N in linear approximation) from the number N of scanning lines, stores it in a memory element, etc. Add to. The operation and configuration of this vertical adjustment processing section 29 are almost the same as those in the conventional example shown in FIG.
When the coefficient calculation unit 28 is provided with a storage element that stores coefficients for each scanning line, the vertical interpolation process is performed using the coefficients read from the storage element of the coefficient calculation unit 28. Therefore, the coefficient generating section 21 shown in FIG. 5 becomes unnecessary. If the coefficient calculation section 28 is not provided with a storage element, a storage element is provided in place of the coefficient generator 21 in the vertical adjustment processing 29, and the coefficient calculation section 28
All you have to do is write the coefficients found in , and perform the same operation as a conventional coefficient generator configured with a ROM or the like. In this way, the number and coefficient values between each adjustment point corresponding to synchronization signals of different frequencies are determined. Next 1
Reading and writing of the frame memory 10 is performed in the same manner as in the prior art. As described above, by detecting the number of scanning lines between one field from the input synchronization signal and finding the number and coefficient value between each adjustment point, even if synchronization signals of different frequencies are input, A tunable digital convergence device can be provided.

Effects of the Invention As described above, according to the present invention, the number of scanning lines detecting section, the number of adjustment points setting section, and the coefficient calculating section are provided to detect the type of synchronization signal (number of scanning lines/one field period), and to Number of scanning lines between adjustment points according to N〓
By automatically setting the coefficient value M/L+1 (L is the number of adjustment points in the vertical direction), the same number of adjustment points can always be displayed on the screen. Therefore, since the adjustment points on the screen do not widen, it is possible to make adjustments with high precision. Although the number of scanning lines is detected by detecting the number of scanning lines in one field, the number of scanning lines may also be detected by detecting the horizontal frequency and vertical frequency. It also has multiple frame memories,
It goes without saying that it is possible to cope with synchronization signals of different frequencies by storing convergence correction amounts corresponding to a plurality of synchronization signals of different frequencies.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the principle of a projection type color TV receiver, Fig. 2 is a diagram for explaining the convergence deviation, Fig. 3 is a block diagram of a conventional digital convergence device, and Fig. 4 is the same. FIG. 5 is a block diagram of a part of the device to explain the operation of the device, and FIG. 6 is a block diagram of a digital convergence device in one embodiment of the present invention. 5... Read address control unit, 6... Crosshatch generator, 7... Video circuit, 8... Write address control unit, 9... Multiplexer, 10...
...1 frame memory, 11 ... data reversible counter, 12 ... control panel, 18 ... register, 14 ... D/A converter, 15 ... LPF,
26...Scanning line detection unit, 27...Adjustment point interval number setting unit, 28...Coefficient calculation unit, 29...Vertical direction adjustment point interval processing unit.

Claims (1)

[Claims] 1. Means for generating and displaying a plurality of convergence adjustment points in the horizontal and vertical directions on the screen of a color TV receiver, means for inputting position information of the adjustment points, and means for digitally calculating the convergence correction amount for the adjustment points. means for storing, means for reading out the stored correction amount, means for detecting the number of scanning lines for one field from the synchronization signal input to the receiver, and scanning between adjustment points from the number of adjustment points in the vertical direction. means for setting the number of lines; means for determining and storing a coefficient value for each scanning line from the number of scanning lines between adjustment points; A digital convergence device characterized in that it is provided with vertical adjustment point-to-point processing means for calculating from coefficient values.