JPS60185482A - Digital convergence device - Google Patents

Abstract

PURPOSE:To apply convergence correction with high accuracy by providing a cross hatch pattern generating circuit forming a longitudinal line at both left/ right ends of screen in addition to longitudinal and lateral lines of equal interval and forming a lateral line at both upper/lower ends of the screen so as to extrapolate a correction amount to an adjusting point at the outside of the screen. CONSTITUTION:A PLL circuit 1 forms an fCLK1 being a frequency N-times fH and a frequency fCLK2 being a frequency M times from a clock signal obtained through MXN multiple of a horizontal deflection frequency (f). A counter 17 counts the fCLK2 of the longitudinal line appearing at both the left/right ends of the screen and a decoder 18 decodes the position at both left/right ends of the screen. The output and the fCLK1 are ORed and a longitudinal line signal of the cross hatch pattern having the longitudinal line at both the left/right ends of the screen is formed through a monostable multivibrator 12. The lateral line of equal interval is generated by frequency-dividing the horizontal deflection frequency fH by a frequency divider 13. The counter 21 counts the fH from the lateral line of both upper/lower screen, and a decoder 22 decodes the position at both ends of upper/lower screen. The signals are ORed by OR circuits 14, 20 and a video output syntheizing the marker signal and the cross hatch pattern signal is obtained by a synthesis circuit 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a digital convergence device that can correct convergence deviation around the screen of a color display with high precision.

[Background of the invention]

Conventionally, as a convergence correction circuit, a method of obtaining a convergence correction waveform in an analog manner using passive elements such as horizontal flyback pulses and vertical deflection waveforms and CJs has been used, but there are problems in terms of convergence correction accuracy. there were. Furthermore, as a method for performing convergence correction with even higher precision, a method of digitally performing convergence correction has been proposed in recent years. digital·
The concept of convergence correction is to store the convergence correction amount at each adjustment point in the address corresponding to each adjustment spark in the storage device, read out the stored correction amount in synchronization with the screen scanning of the electron beam, and convert it from D to A. This is an attempt to create a coherence correction waveform.

This conventional digital convergence correction device is
This will be explained using Figure 2.

In FIG. 1, 1 is a PLL circuit that multiplies the horizontal deflection frequency @f■ by N, 2 is an address counter that generates an address synchronized with screen scanning, 3 is a frame memory that stores correction data, 4 is a DA converter, 5 is a low pass filter, 6
is a multiplexer for switching addresses; 7 is a multiplexer for switching data; 8 is a microcomputer; 9 is a keyboard; 1o is a coincidence detection circuit; 11
12 is a monostable multi-channel circuit, 13 is a frequency dividing circuit, 14 is an OR circuit, 15 is a synthesis circuit, 3o is a video output terminal for outputting a crosshatch pattern and a marker, and 31 is an output terminal for a correction waveform. Further, in FIG. 2, 5o is a display screen, and 51 is a crosshatch pattern.

Convergence adjustments are made using the keyboard using a crosshatched adjustment pattern on the screen. First, select the electron beam of the color you want to adjust using the keyboard. Next, select the adjustment point to be adjusted using the marker movement key. The selected adjustment points are arranged in a crosshatch pattern, and the bright spots with high brightness are used as markers to inform the adjuster of the adjustment point positions. Then, while looking at the screen, the correction data stored in the memory is increased or decreased using the data write key, and the correction data is corrected so that the red, green, and blue beams match.

Below, the adjustment points for the on-screen money are made in the same manner. Regarding the amount of correction between adjustment points, interpolation is performed in the horizontal direction by a low-pass filter 5, and in the vertical direction, interpolation calculation is performed by the microcomputer 8 from the correction data of vertically adjacent adjustment points, and the results are written into the frame memory 5. In addition, in order to improve convergence correction accuracy around the screen, frame memory exists outside the screen, and the correction data on the screen is
Extrapolation is performed and written to frame memory. When correcting as described above, each adjustment point can be corrected independently, so convergence correction can be performed with high accuracy.However, since the correction data in the frame memory that exists outside the screen is extrapolated, it is not possible to use the optimal correction data. There may be cases where this is not the case.

In response to this, there has been an attempt to further improve the accuracy of convergence correction around the screen by providing adjustment points outside the screen and using optimal correction data. However, since the adjustment point is outside the screen, you will have to look around the screen to make adjustments. In this case, the second
In the conventional m-scheme pattern shown in the figure, which uses equally spaced vertical and horizontal lines, when trying to adjust both the left and right edges of the screen, the horizontal lines extend to both the left and right edges of the screen, so it is possible to adjust the convergence of the horizontal lines, but it is not possible to adjust the convergence of the horizontal lines. The lines cannot be adjusted because they do not exist on both the left and right edges of the screen. Further, although vertical lines extend to both the upper and lower ends of the screen, horizontal lines do not exist at both the upper and lower ends of the screen, so there is a drawback in that it is impossible to adjust the convergence of the horizontal lines.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital convergence device that enables adjustment even at adjustment points that exist outside the screen and improves the accuracy of convergence correction around the screen.

[Summary of the invention]

In order to achieve the above object, in the present invention, in order to make it possible to adjust adjustment points that exist outside the screen, in addition to vertical and horizontal lines at equal intervals, vertical lines are used at both the left and right ends of the screen as adjustment crosshatch patterns. A crosshatch pattern generation circuit is installed to create horizontal lines at both the top and bottom edges of the screen, and the vertical and horizontal lines added to the periphery of the screen are used to calculate the amount of convergence correction at the periphery of the screen, and the convergence correction is performed. By extrapolating the correction amounts at adjustment points that exist outside the screen from the amount, highly accurate convergence correction can be performed using the correction amounts for these adjustment points that exist outside the screen.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIG. 3.4. Here, the same parts as in Fig. 1.2 are denoted by the same numbers. In the PLL circuit 1 shown in FIG. 6, the clock signal fH is obtained by multiplying the horizontal deflection frequency f by MxN.
fcLKI, which is N times the frequency of +, and fCLK2, which is M times the frequency of +, are created from this fct. A counter 17 counts fCLK2 for vertical lines appearing on both the left and right ends of the screen, and a decoder 18 decodes the positions of the left and right ends of the screen. By ORing this decoded output and fcLKI and passing it through the monostable multi 12, it is possible to create a vertical line signal in a crosshatch pattern with vertical lines at both left and right ends of the screen. As for the horizontal lines, equally spaced horizontal lines are generated by dividing the horizontal deflection frequency fH by the frequency divider 13.

The horizontal lines at both the top and bottom ends of the screen are created by counting fH with a counter 21 and decoding the positions of both the top and bottom ends of the screen with a decoder 22. The signals that generate the vertical and horizontal lines of these crosshatch patterns are supplied to OR circuits 14 and 20.
The OR is taken, and the synthesis circuit 15 produces a video output in which the marker signal and the crosshatch pattern signal are synthesized. Also, the marker signal is sent to the coincidence detection circuit 1 when the addresses given by the address counter 2 and the microcomputer B match.
0 is detected, and this detection pulse is made into a signal with a narrowed pulse width by a monostable multi 11. The marker signal obtained is further passed through a marker control circuit 16 to control lighting and blinking of the X-force by a microcomputer 8. conduct. This marker is controlled by lighting up at the adjustment point on the screen.
When the adjustment point is outside the screen, the adjustment point is blinked at the outermost position of the adjustment point on the screen, so that the adjuster can know that the adjustment point outside the screen has been selected.

As shown in FIG. 4, the crosshatch pattern displayed on the screen by the circuit configuration described above has vertical lines at both the left and right ends of the screen, and horizontal lines at both the top and bottom ends of the screen.

〔Effect of the invention〕

As explained above, according to the present invention, convergence correction for adjustment points outside the screen is performed by checking the vertical and horizontal lines that intersect at both the left and right ends of the screen and at both the top and bottom ends of the screen. By adjusting the convergence of
It is possible to obtain correction data that is far more accurate than correction data calculated by extrapolation from the correction amount of the adjustment point at the outermost circumference of a conventional crosshatch pattern consisting of regularly spaced vertical and horizontal lines.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional digital convergence device, Fig. 2 is a block diagram of an embodiment of the present invention, and Fig. 4 is a block diagram of a conventional four-shape pattern for convergence adjustment. FIG. 3 is a diagram of a crosshatch pattern for convergence adjustment. 1...PLL circuit, 2...Address counter, 3
...Frame memory, 4...DA converter, 5...
Low-pass filter, 6.7... Multiplexer, 8... Microcomputer, 9... Keyboard, 10... Coincidence detection circuit, 11.
12... Monostable multi, 13... Frequency divider circuit, 14,19.20... OR circuit, 15... Synthesis circuit, 16... Marker control circuit, 17.21... Counter, 18.22...Decoder, 30...Video signal output terminal, 31...Correction waveform output terminal, 50.51 A cress hatch pattern. Representative Patent Attorney Akio Takahashi

Claims (1)

[Claims] It is a raster scan type color display that has m horizontally and vertically n convergence adjustment points in m columns x n rows, and the correction amount at each adjustment point is digitally stored in the corresponding address of the storage device. In a digital convergence device that performs convergence correction by reading out the stored correction amount in synchronization with screen scanning, are you selecting an adjustment point within the screen or an adjustment point outside the screen? , with a marker, and in conjunction with this means, vertical lines and horizontal lines are displayed around the screen at intervals that do not necessarily match the intervals of equally spaced vertical lines and horizontal lines on the inside of the screen as an adjustment crosshatch pattern. and a circuit for projecting the image, and the correction amount obtained from the line projected around the screen is used to extrapolate the correction amount at the adjustment point outside the screen and used for convergence correction. Digital convergence device.