JPH09182096A - Auto-convergence circuit - Google Patents

Abstract

(57) Abstract: It is an object of a three-tube projection television to automatically correct a deviation in dynamic convergence due to a deviation in the rotational direction of a raster that cannot be adjusted only by static convergence. A detector 1, which detects a deviation from an initial value of a reference signal superimposed on an overscan portion of a video signal.
2 and a microcomputer 1 for controlling the amount of correction, and a circuit for converting the output from the microcomputer by a DAC to control the gain of the convergence output circuit. The voltage detected by the detectors 1 and 2 causes a sawtooth wave to the convergence coil. By applying the correction current, when the deviation of the dynamic convergence due to the rotation direction of the raster occurs, it is automatically corrected to the initial adjustment value to eliminate the color deviation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection tube (hereinafter CR
The present invention relates to a dynamic convergence circuit (analog) among color superposition (hereinafter referred to as convergence) circuits of a projection television using three Ts.

[0002]

2. Description of the Related Art In the past, the dynamic convergence of projection type televisions was all factory adjusted, and it was impossible for the user to adjust the misconvergence at the time of installation, which is a drawback of projection type televisions. However, since a static convergence function of adjusting misconvergence in the horizontal and vertical directions of the screen by supplying a direct current to the convergence coil is generally provided, adjustment at the time of installation is possible.

Further, as disclosed in Japanese Patent Application Laid-Open No. 4-282993, in a circuit having digital convergence, there has been proposed a configuration for correcting misconvergence by comparing data with an initial value.

[0004]

However, as described above, the misconvergence cannot be absorbed only by adjusting the static convergence. The horizontal and vertical deviations of the horizontal and vertical external magnetic fields with respect to the CRT can be adjusted by static convergence, but the static convergence can be applied to the deviations other than the horizontal and vertical directions due to a rotating magnetic field. It cannot be adjusted by convergence.

Therefore, according to the present invention, a deviation of the reference signal superimposed on the overscan portion of the video signal is detected, a correction current for the sawtooth wave is applied to the horizontal and vertical convergence coils according to the deviation, and the motion is generated by the rotation of the raster. The purpose is to automatically correct the deviation of convergence.

[0006]

In order to achieve the above object, the means of the present invention is to detect voltage from a detector 1 for detecting a horizontal deviation and a detection voltage from a detector 2 for detecting a vertical deviation. It is fed back to the microcomputer and compared with the initial adjustment value.When deviation occurs, the microcomputer data is corrected so that it becomes the same as the initial adjustment value, and a sawtooth wave to flow to the horizontal and vertical convergence coils is provided. It is a thing.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention uses a detection circuit for detecting a deviation from an initial adjustment value of a reference signal superimposed on an overscan portion of a video signal and an output from the detection circuit. A control unit for controlling the correction wave to an arbitrary value is provided, and a vertical sawtooth correction current is applied to the horizontal convergence coil according to a control signal from the control unit to automatically correct the color misregistration in the horizontal direction. With an auto-convergence circuit, when misconvergence occurs due to an external magnetic field such as a rotating magnetic field, it detects that the output voltage from the detector deviates from the initial value, and the microcomputer matches the deviation with the initial value. The vertical sawtooth wave that flows in the horizontal convergence coil is controlled by the output voltage from this microcomputer. It has the effect of automatically correcting the misconvergence.

According to a second aspect of the present invention, in the convergence circuit of the first aspect, a horizontal sawtooth correction current is supplied to the vertical convergence coil to automatically correct a color misregistration in the vertical direction. This is an auto-convergence circuit that detects when the output voltage from the detector deviates from the initial value when misconvergence due to an external magnetic field such as a rotating magnetic field occurs, and the microcomputer tries to match the deviation with the initial value. The horizontal sawtooth wave that flows through the vertical convergence coil is controlled by the output voltage from the microcomputer, thereby automatically correcting the vertical misconvergence.

According to a third aspect of the present invention, in the first and second aspects, a combination of applying a vertical sawtooth correction current to the horizontal convergence coil and passing a horizontal sawtooth correction current to the vertical convergence coil are combined. An auto-convergence circuit that automatically corrects horizontal and vertical color misregistration. Detects when the output voltage from the detector deviates from the initial value when misconvergence occurs due to an external magnetic field such as a rotating magnetic field. However, the microcomputer operates to match the deviation with the initial value, and by controlling the vertical sawtooth wave sent to the horizontal convergence coil by the output voltage from this microcomputer, and further controlling the horizontal sawtooth wave sent to the vertical convergence coil. , Automatically corrects horizontal and vertical misconvergence To.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a block diagram of an auto-convergence circuit according to an embodiment of the present invention. In FIG. 1, reference numerals 1 and 2 denote a color shift detection circuit, 3 a microcomputer, 4 a memory, 5 horizontal and vertical correction DACs, 6 a reference signal switching circuit, 7 an R convergence output circuit,
Reference numeral 8 indicates a G convergence output circuit, and 9 indicates a B convergence output circuit.

The detectors 1 and 2 detect deviations from the initial adjustment values in the R, G, and B rotation directions based on the reference signal superimposed on the video signal.

As the reference signal, as shown in FIG. 2, luminance signals of vertical lines in the horizontal direction and horizontal lines in the vertical direction are put in a black frame. This reference signal is configured so that the microcomputer 1 outputs R, G, B signals in a time division manner in order to detect the R, G, B positions.

That is, when detecting the position of R, a red luminance signal is output in a black frame, when G is green, a green luminance signal and when B is a blue luminance signal.

The detectors 1 and 2 have a positional relationship in which two optical sensors are arranged on both sides of the luminance signal portion of the reference signal in order to precisely detect the horizontal and vertical positions of R, G and B. The microcomputer 1 uses the detector 1,
The data from 2 is taken in and compared with the initial values of R, G and B respectively.

As a result, when a horizontal shift is detected, the vertical sawtooth waves of R, G, and B are simultaneously controlled by the DAC 1, and the vertical sawtooth wave is applied to the horizontal convergence coil so that the correction H of FIG. 2 is applied. The misconvergence is eliminated by flowing the correction current of (2) and controlling it so that it becomes the same as the initial adjustment value.

(Second Embodiment) As in the first embodiment, when a vertical shift is detected, the horizontal sawtooth waves of R, G, and B are simultaneously controlled by the DAC 1 to correct the correction shown in FIG. Misconvergence is eliminated by applying a correction current of a horizontal sawtooth wave to the vertical convergence coil so as to apply V so that the current becomes equal to the initial adjustment value.

(Embodiment 3) When Embodiments 1 and 2 are combined and a horizontal and vertical deviation is detected,
DAC for horizontal and vertical sawtooth waves of R, G, B respectively
By simultaneously controlling with 1, the correction currents of the vertical and horizontal sawtooth waves are applied to the horizontal and vertical convergence coils so that the correction H and the correction V of FIG. 2 are applied, and the control is made to be the same as the initial adjustment value. , Eliminate misconvergence.

[0018]

As is clear from the above description, the auto-convergence circuit of the present invention eliminates the deviation in the rotational direction of the dynamic convergence that cannot be absorbed by the installation adjustment of the static convergence, which is required for the projection type television. By automatically adjusting the analog convergence circuit as well, it is possible to maintain a screen without color shift.
Further, the same effect can be obtained with respect to the change over time due to the temperature of the correction wave for adjusting the dynamic convergence.

[Brief description of the drawings]

FIG. 1 is a block configuration diagram of an auto-convergence circuit according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an example of a detection unit and operation of FIG.

[Explanation of symbols]

 1, 2 color misregistration detection circuit 3 Microcomputer 4 Memory 5 Horizontal and vertical correction DAC 6 Reference signal switching circuit 7 R convergence output circuit 8 G convergence output circuit 9 B convergence output circuit

Claims (3)

[Claims] 1. A detection circuit for detecting a deviation from an initial adjustment value of a reference signal superimposed on an overscan portion of a video signal, and a control portion for controlling a correction wave to an arbitrary value by an output from the detection circuit. An auto-convergence circuit, comprising: a vertical sawtooth correction current that flows through the horizontal convergence coil in response to a control signal from the control unit to automatically correct horizontal color misregistration. 2. The auto-convergence circuit according to claim 1, wherein a horizontal sawtooth correction current is passed through the vertical convergence coil to automatically correct the color misregistration in the vertical direction. 3. A method in which a vertical sawtooth correction current is passed through the horizontal convergence coil and a horizontal sawtooth correction current is passed through the vertical convergence coil to automatically correct horizontal and vertical color misregistrations. The auto-convergence circuit according to claim 2, which is characterized in that.