JPH07143504A - Geomagnetic corrector - Google Patents

Abstract

PURPOSE:To provide a geomagnetic corrector with high correction precision. CONSTITUTION:A current 5 from a control means 3 is superimposed to a geomagnetic correcting coil 4, a magnetic field for canceling geomagnetism is generated from the geomagnetic correcting coil 4, the tube surface luminance of a color cathode-ray tube 1 is increased just for this canceled geomagnetism, this is detected by a luminance detecting means 2 and when the geomagnetism is completely canceled, the tube surface luminance is made maximum. Therefore, the control means 3 converts the output signal of the luminance detecting means 2 to a digital signal by using an A/D converter 31, a CPU 32 operates an output signal so as to maximize the digital signal value from the A/D converter 31, this output signal is converted into an analog signal by a D/A converter 33 and transmitted to an amplifier 34, the amplified analog signal is turned to the superimpose current 5 and superimposed to the geomagnetic correcting coil 4, and the output of the luminance detecting means 2 is made maximum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a geomagnetism correction device for a display device using a color cathode ray tube.

[0002]

2. Description of the Related Art A display device using a color cathode ray tube is
There are problems such as deterioration of color purity and inclination of the display screen due to the influence of geomagnetism, and there is a magnetic shield as a method of reducing the influence of geomagnetism, but it is not possible to shield the geomagnetism completely. A general method is to cancel the geomagnetism by generating a magnetic field in the opposite direction with the same strength as.

Therefore, as shown in FIG. 2, the conventional geomagnetism correction device uses the variable resistor VR connected to the power sources + B and -B via the resistors R1 and R2, to correct the geomagnetism correction coil 4.
The strength and direction of the magnetic field generated in the magnetic field are controlled by the output of the comparator IC connected to the slider of the variable resistor VR, and the transistor Q connected to the geomagnetic correction coil 4 is controlled.
1 and Q2 are changed by the bias set by the resistors R3 and R4 and the diodes D1 and D2, and are adjusted to the point where the deterioration of color purity and the inclination of the display screen are minimized, and the influence of the earth's magnetism can be reduced.

[0004]

In the conventional geomagnetism correction device, since the point where the deterioration of the color purity and the inclination of the display screen are minimized is visually adjusted, it is difficult to find the optimum adjustment point and the correction accuracy is low. There was a problem.

Therefore, an object of the present invention is to provide a geomagnetism correction device having high correction accuracy.

[0006]

In order to solve the above-mentioned problems, a geomagnetic correction device of the present invention comprises a color cathode ray tube,
A geomagnetism correction coil which is arranged in the vicinity of the color cathode ray tube and generates a magnetic field to cancel the geomagnetism of the color cathode ray tube, and detects the brightness of the surface of the color cathode ray tube.
Alternatively, a brightness detecting means having a plurality of light receiving elements, and a control means for supplying a superimposed current to the geomagnetic correction coil such that the brightness value of the surface of the color cathode ray tube becomes maximum based on the output signal of the brightness detecting means. It is composed of and.

In order to solve the above-mentioned problems, the geomagnetism correction device of the present invention has an A / D converter for digitally converting the output signal of the brightness detecting means and a digital conversion by this A / D converter. And a D / A converter for converting the digital signal calculated by this CPU into an analog signal, and a D / A converter for converting the digital signal calculated by this CPU into an analog signal. The control means comprises an amplifier for supplying a superimposed current obtained by amplifying a digital signal analog-converted by the converter to the geomagnetic correction coil.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a geomagnetic correction device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a geomagnetism correction device according to an embodiment of the present invention.

As shown in FIG. 1, a geomagnetism correction apparatus according to an embodiment of the present invention includes a color cathode ray tube 1 and a color cathode ray tube 1 which is arranged in the vicinity of the color cathode ray tube 1 and generates a magnetic field. Geomagnetic correction coil 4 that cancels the geomagnetism
And a brightness detecting means 2 including one or a plurality of light receiving elements 21 to 2N for detecting the brightness of the surface of the color cathode ray tube 1.
Based on the output signal of the brightness detecting means 2, the control means 3 supplies a superimposed current 5 to the geomagnetism correction coil 4 so that the brightness value of the surface of the color cathode ray tube 1 becomes maximum.

Further, the control means 3 of the geomagnetism correction device of the present invention performs digital conversion of the output signal of the brightness detection means 2 A
A / D converter 31 and a CPU 32 that calculates a digital signal that maximizes the brightness value of the surface of the color cathode ray tube 1 based on the output signal digitally converted by the A / D converter 31.
And a D / A converter 33 for converting the digital signal calculated by the CPU 32 into an analog signal, and the D / A converter 33.
An amplifier 34 for supplying the superimposed current 5 obtained by amplifying the digital signal analog-converted by
Composed of and.

Next, the operation of the geomagnetic correction device according to one embodiment of the present invention will be described with reference to FIG.

First, the superposed current 5 output from the control means 3 is superposed on the geomagnetism correction coil 4 to generate a magnetic field for canceling the geomagnetism from the geomagnetism correction coil 4. The brightness of the tube surface rises, and when this is detected by the brightness detecting means 2 and the geomagnetism is completely canceled, the brightness of the tube surface becomes maximum.

Therefore, the control means 3 converts the output signal of the brightness detection means 2 into a digital signal by the A / D converter 31,
The CPU 32 calculates the output signal so that the digital signal value from the A / D converter 31 becomes maximum, and the D / A converter 3
3 is converted into an analog signal, and the analog signal amplified by being sent to the amplifier 34 becomes the superimposed current 5, and the superimposed current 5 is superimposed on the geomagnetism correction coil 4, and the brightness detection means 2
Output becomes maximum and the geomagnetic correction is completed.

[0015]

As described above, according to the geomagnetism correction apparatus of the present invention, since the tube surface luminance of the color cathode ray tube is detected and the geomagnetism is corrected, the geomagnetism correction with high correction accuracy can be realized. .

[Brief description of drawings]

FIG. 1 is a block diagram of a geomagnetism correction device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a conventional geomagnetism correction device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color cathode ray tube 2 Luminance detection means 3 Control means 4 Geomagnetic correction coil 5 Superimposed current 21 to 2N Light receiving element 31 A / D converter 32 CPU 33 D / A converter 34 Amplifier

Claims (2)

[Claims] 1. A color cathode ray tube, a geomagnetism correction coil which is arranged in the vicinity of the color cathode ray tube and which generates a magnetic field to cancel the geomagnetism of the color cathode ray tube, and detects the brightness of the surface of the color cathode ray tube. Luminance detecting means having one or a plurality of light receiving elements, and control for supplying a superimposed current to the geomagnetic correction coil so that the luminance value of the surface of the color cathode ray tube becomes maximum based on the output signal of the luminance detecting means. A geomagnetism correction device comprising: 2. An A / D converter that digitally converts the output signal of the brightness detecting means, and a maximum brightness value of the surface of the color cathode ray tube based on the output signal digitally converted by the A / D converter. CPU for calculating digital signals
And a D / A converter for converting the digital signal calculated by the CPU into an analog signal, and a superimposed current obtained by amplifying the digital signal converted by the D / A converter into the geomagnetic correction coil. 2. The geomagnetism correction device according to claim 1, wherein the geomagnetism correction device is configured by the control means including an amplifier that operates.