JPH05227536A - Digital convergence device - Google Patents

Abstract

PURPOSE:To cope with even various scanning frequencies or a screen size by one correction data by arranging a zone address generator so as to generate the zone address of a correction data memory which stores a color deviation correction value corresponding to the physical position of the display screen of a CRT. CONSTITUTION:The color deviation correction data are stored in a correction data memory 2, the data are converted into an analog value by a D/A converter 3, and a color deviation correcting coil 1 is driven. Addresses corresponding to the zones obtained by dividing a raster scanning range into horizontal and vertical parts are allocated to the correction data memory 2. A zone address generator 4 detects the currents of a deflection coil 9, generates the zone address corresponding to the raster scanning based on the detected current value, and reads the correction data corresponding to the pertinent zone from the correction data memory 2. A correction data inputting part 6 inputs the correction data to the correction data memory 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic convergence device for correcting color misregistration of a color cathode ray tube, and more particularly to a digital convergence device in which color misregistration correction data is digitally stored.

[0002]

2. Description of the Related Art A display on a cathode ray tube (hereinafter referred to as CRT) is composed of a plurality of scanning lines on a display surface. This scanning line is drawn on the inner surface of the CRT by the electron beam generated inside the CRT. The intensity of the electron beam is controlled simultaneously with the scanning of the inner surface of the CRT with the electron beam. Since red, green, and blue electron beams often do not coincide with one another during scanning,
Convergence correction is required to match these three electron beams to appropriate points. In order to perform such convergence correction, conventionally, static convergence correction has been used in which permanent magnets are combined and three electron beams are relatively moved to correct color misregistration.

With the use of this permanent magnet, it is difficult to finely correct the color misregistration over the entire phosphor screen, and when the color misregistration correction of 1 mm or less is required, a magnetic field equivalent to that of the permanent magnet is generated using a coil. Dynamic convergence correction is performed in which the current generated in a magnet is changed in accordance with raster scanning to change the current.

Conventionally, an analog generation system in which a variable resistor or the like is combined has been used as a means for generating a correction current for the dynamic convergence.
Along with the progress of digital technology, a digital convergence device that digitally stores a correction current value has been proposed.

FIG. 4 shows a block diagram of this conventional digital convergence apparatus. In the digital convergence device 5, the color shift correction data is stored in the correction data memory 2, the data is converted into an analog value by the digital / analog converter (hereinafter referred to as D / A) 3, and the color shift correction coil 1 is driven. In the correction data memory 2,
As shown in FIG. 5a, addresses corresponding to zones obtained by dividing the raster scanning range into some horizontal and vertical are assigned. The zone address generator 4 generates a zone address corresponding to raster scanning based on the synchronization signal from the deflection circuit 8 and reads the correction data corresponding to the corresponding zone from the correction data memory 2. The correction data input unit 6 inputs the correction data to the correction data memory 2. For example, when there is a color shift in the central vertical direction as shown in FIG. 5a, the color shift can be corrected in the entire raster scanning range by storing the data shown in FIG. 5b in the correction data memory 2.

In order to perform more accurate color shift correction,
It suffices to divide the zone into smaller pieces and increase the number of bits of the correction data.

[0007]

SUMMARY OF THE INVENTION In the above-mentioned conventional example,
In a general display application, since the scanning frequency and the screen size are different for each user, when the scanning frequency and the screen size are changed, the color shift cannot be correctly corrected with the previously corrected data. Conventionally, a plurality of correction data are stored for each scanning frequency, or the correction data is further corrected by screen size information. But,
There is a problem that a large-capacity memory is required because a large amount of correction data must be stored, and an arithmetic circuit is required for correction.

The present invention solves the above-mentioned problems of the prior art, and one correction data can be applied to various scanning frequencies, and can also be applied to change the screen size. It is an object to provide a digital convergence device.

[0009]

In order to achieve the above-mentioned object, according to the present invention, the amount of color shift of the CRT mainly depends on the physical position of the display tube surface and depends on the scanning frequency and the screen size. Paying attention to the fact that the amount of current is small and that the physical position of the display tube surface depends on the amount of current flowing in the deflection coil, the zone address generator of the digital convergence device is equipped with means for detecting the current in the deflection coil and It has a configuration including a conversion unit that associates the selected current value with a raster scan zone address.

[0010]

According to the present invention, since the deflection current is detected and the zone address is generated by the above-described structure, the zone address corresponding to the physical position of the display tube surface can be always generated, and one correction is made. With data, color shift correction can be performed without depending on the scanning frequency or screen size.

[0011]

1 is a block diagram of a digital convergence apparatus according to the present invention. In the figure, the same blocks as those in FIG. 4 are denoted by the same reference numerals.

In the digital convergence device 5, the color shift correction data is stored in the correction data memory 2, the data is converted into an analog value by the D / A 3, and the color shift correction coil 1 is driven. As in the conventional example, the correction data memory 2 is assigned addresses corresponding to zones obtained by dividing the raster scanning range into several horizontal and vertical areas. The zone address generator 4 detects the current of the deflection coil 9, generates a zone address corresponding to raster scanning based on the detected current value, and reads the correction data corresponding to the corresponding zone from the correction data memory 2. The correction data input unit 6 inputs the correction data to the correction data memory 2. Similar to the conventional example, when there is a color shift in the central vertical direction as shown in FIG. 5a, by storing the data shown in FIG. 5b in the correction data memory 2,
Color misregistration can be corrected in the entire raster scanning range.

Next, the zone address generator 4, which is a feature of the present invention, will be described with reference to FIGS.

FIG. 2 is a block diagram of the zone address generator 4. In FIG. 2, 10-1 is a horizontal deflection current detection circuit for detecting the current flowing in the horizontal deflection coil, 10
Reference numeral -2 is a vertical deflection current detection circuit that detects a current flowing through the vertical deflection coil. Reference numerals 11-1 and 11-2 denote analog / digital converters (hereinafter referred to as A / D converters) for converting the current values detected by the horizontal deflection current detection circuit 10-1 and the vertical deflection current detection circuit 10-2 into digital values. Say)
Is. 12 is A / D 11-1 and A / D 11
It is a decoder circuit for converting the horizontal and vertical deflection current values converted into digital values by -2 into zone addresses of the correction data memory 2.

Next, the operation of the zone address generator 4 composed of the above blocks will be described.

FIG. 3a is a diagram showing the state of the zone address generator 4 at a certain standard scanning frequency and screen size. The correction data memory 2 stores the data corrected in this state. In contrast, FIG. 3b
As described above, if the scanning frequency does not change and the vertical screen size is reduced, the scanning area of the raster is reduced toward the center. On the other hand, the vertical deflection current has a shape in which the amplitude of the waveform is contracted around the center point of the sawtooth wave (the center of the screen). At this time, the detected current value is output from the A / D 11-2 as shown in FIG. 3B, and the zone address converted by the decoder circuit 12 becomes a value corresponding to the physical position on the display tube surface of the CRT. Therefore, from the correction data memory 2, C
The correction value corresponding to the physical position of the RT display tube surface can be read. Similarly, if the vertical screen size does not change and the scanning frequency is increased as shown in FIG. 3C, the scanning area of the raster does not change, but the cycle of the sawtooth wave of the vertical deflection current becomes short. At this time, the detected current value is output from the A / D 11-2 as shown in FIG.
The zone address converted in 2 has a value corresponding to the physical position of the display tube surface of the CRT. Therefore, the correction value corresponding to the physical position of the display tube surface of the CRT can be read from the correction data memory 2.

Therefore, the data corrected in the state of FIG. 3a can be used even when the state is changed to the states of FIGS. 3b and 3c.

As described above, according to this embodiment, the zone address generator is arranged so as to select the zone address of the correction data memory according to the deflection current amplitude.
Color misregistration can be corrected according to changes in screen size and scanning frequency.

Although the A / D is used in this embodiment to convert the deflection current value into a digital value, in the case of a simple type in which the zone division is rough, a comparator is used. You may.

[0020]

As is apparent from the embodiments described above, according to the present invention, the zone address of the correction data memory in which the color misregistration correction value is always stored in correspondence with the physical position of the display tube surface of the CRT is set. Since the zone address generator is arranged so that it will occur, only one correction data is required, and even if the scanning frequency or screen size changes,
It is possible to provide a digital convergence device that does not require correction data change processing or correction processing.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a digital convergence device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an embodiment of a zone address generator in the device.

FIG. 3 is an operation explanatory diagram of the present invention.

FIG. 4 is a block diagram showing a configuration of a conventional digital convergence device.

FIG. 5 is an operation explanatory diagram of digital convergence correction.

[Explanation of symbols]

 4 zone address generator 10 current detection circuit 11 A / D converter 12 decoder circuit

Claims (1)

[Claims] 1. A color misregistration correction coil for correcting a color misregistration of a cathode ray tube, a digital memory for storing the correction amount, and a raster scanning position and a memory address from the memory in synchronization with raster scanning. A zone address generator to be associated with, by converting the data read from the memory address specified by the zone address generator into an analog amount, in a convergence device for correcting the color misregistration, in the zone address generator,
A digital convergence device comprising means for detecting a deflection current flowing through a deflection coil, means for converting the detected deflection current into a digital amount, and conversion means for associating the converted digital amount with the memory address.