JPH0254713B2 - - Google Patents

Description

[Detailed Description of the Invention] Since vertical and horizontal pink distortions generally occur in television receivers, circuits are provided to correct these screen distortions. Even in the receiver,
If the installation accuracy of the horizontal and vertical deflection coils, that is, the orthogonality of both deflection coils is poor, or if there is an influence of the earth's magnetic field, for example, the problem may occur with respect to the X-X' axis in a parallelogram shape as shown in Figure 1. Asymmetric screen distortion occurs.

In ordinary television receivers, even in such cases, there is no practical effect, so correction of this asymmetric screen distortion is rarely done. In high-end television receivers such as TVs, it is necessary to correct screen distortion as described above.

Therefore, conventionally, screen distortion has been corrected by adjusting the mechanical positions of the horizontal deflection coil and the vertical deflection coil while looking at the screen before shipping.
Therefore, in this conventional method, adjustments for correcting screen distortion are complicated and take a long time, and there is also a drawback that correct adjustments cannot be made.

Therefore, in this invention, even such asymmetric screen distortion can be corrected purely electronically.
This eliminates the above-mentioned drawbacks. Hereinafter, an example of the present invention will be described with reference to FIG. 2 and below for a case where both screen distortions, ie, parallelogram distortion, which is asymmetrical screen distortion, and upper and lower pink distortion, which is symmetrical screen distortion, are simultaneously corrected with a simple configuration. explain.

In other words, the screen distortion to be corrected in this invention is as shown in Figure 2, and this screen distortion
S _A is a combination of the vertical pink tension strain S _C shown in Figure 3 and the parallelogram strain S _B shown in Figure 1. Therefore, in order to correct the screen distortion S _A , it is sufficient to simultaneously correct the upper and lower pink distortion S _C and the parallelogram distortion S _B. Upper and lower pink tension distortion S _C is shown in Figure 5A.
As shown in , it is sufficient to supply the signal C _C obtained by modulating the horizontally periodic parabolic wave signal (horizontal parabolic wave signal) C _P with the vertical sawtooth wave signal T _V to the vertical output circuit as a correction signal. The distortion S _B can be corrected by applying the concept of correcting the trapezoidal distortion (screen distortion symmetrical to the X-X' axis) S _D shown in FIG. 4. In other words, the trapezoidal distortion S _D is as shown in Figure 5B.
Convert horizontal sawtooth signal T _H to vertical sawtooth signal T _V
Since it can be corrected using the correction signal C _D which has been subjected to balance modulation, this correction signal C _D can be modified and used to suit the purpose.

Figure 6 shows a specific example for correcting screen distortion S _A , in which the input video signal S _i supplied to terminal 1 is supplied to synchronization separation circuits 2 and 3, and a horizontal synchronization pulse P _H is output from one of the circuits 2 and 3. The vertical synchronizing pulse P _V is separated from the other one. The horizontal synchronizing pulse P _H is supplied to a sawtooth signal forming circuit 5 via a variable phase shifter (described later) 4 to form a horizontal sawtooth signal T _H having a horizontal period. Horizontal sync pulse P _H is
The output of the AFC circuit may also be used.

The vertical synchronizing pulse P _H is also supplied to the vertical sawtooth signal forming circuit 6 to generate the vertical sawtooth signal T _V (7th
Figure D) is formed, and this and the horizontal sawtooth signal
T _H is supplied to the first balance modulator 7, which converts the horizontal sawtooth signal T _H into a vertical sawtooth signal.
The first signal shown in FIG. 7A is modulated by a _TV .
C _D is output.

When the horizontal sawtooth signal T _H is modulated, the phase of the horizontal sawtooth signal T _H is reversed between the first half and the second half of the vertical deflection center point (corresponding to the X-X' axis). Note that since this first signal _CD is the correcting signal itself shown in FIG. 5B, the parallelogram distortion S _B shown in FIG. 1 cannot be corrected by this first signal _CD .

The horizontal sawtooth signal T _H is further supplied to the integrating circuit 8 to form a horizontal parabolic wave signal C _P (Fig. 7B), and this horizontal parabolic wave signal C _P and the first signal C _D are subjected to an operation for addition. The signal is supplied to the amplifier 9 and processed with the polarity shown in the figure. Therefore, this addition output C _E is a composite signal C _DE containing horizontal parabolic wave components and horizontal sawtooth wave components as shown in Fig. 7C.
As shown in the figure, in the first half of the vertical period, the peak point of the composite signal C _DE (maximum vertical deflection point in each horizontal period) shifts to the right than in the normal case, and therefore to the second half of the horizontal period, In the second half of the vertical period, there is a converse shift to the left, and thus to the first half of the horizontal period.

However, the phases of the horizontal parabolic wave signal C _P and the horizontal sawtooth wave signal C _D included in this addition output C _E do not change even after the addition, so they are the same as those in FIGS. 7A and B. If they are in the same phase, the horizontal parabolic wave signal C _P cannot correct the vertical pink distortion S _C shown in Figure 3, and the horizontal sawtooth wave signal C _D cannot correct the parallelism distortion S C shown in Figure 1. Shape distortion cannot be corrected. Therefore, the present invention further includes the following configuration.

That is, this addition output C _E is supplied to the second balance modulator ₁₁ together with the vertical sawtooth wave signal TV, and the addition output C _E is balanced modulated by the vertical sawtooth signal _TV , resulting in the output shown in FIG. 7E. A correction signal C _A shown in FIG.

As a result of the balance modulation, the phase of the second half of the addition output C _E is inverted, so the phase of the horizontal parabolic wave signal C _P in the addition output C _E is reversed between the first half and the second half of the vertical period, and it becomes a horizontal sawtooth wave signal. C _D has the same phase during the vertical period.

Since the vertical pink tension distortion S _C is symmetrical with respect to the X-X' axis, in order to correct this distortion S _C , the distortion correction signal in the second half of the vertical period must be in opposite phase to the first half of the vertical period. Looking at the correction signal C _A mentioned above, the horizontal parabolic wave signal C _P for upper and lower pink distortion correction included in the composite signal C' _DE has the phase reversed in the first half and the second half of the vertical period, so first,
This correction signal C _A can correct the vertical pink tension distortion shown in FIG.

Since the parallelogram strain S _B is equivalent to the trapezoidal strain S _D shown in Fig. 4, only the latter half of which is inverted, this strain S _B
To correct this, it is necessary to invert the phase of the second half of the vertical period of the correction signal C _D of the trapezoidal distortion S _D. In other words, the phases of the horizontal sawtooth signals C _D must be in phase. Looking at the correction signal C _A mentioned above, since the slope of the composite signal C' _DE is the same in the first half and the second half of the vertical period, the horizontal sawtooth wave signal C for parallelogram distortion correction included in the composite signal C' _DE The phase of _D does not change during the vertical period. Therefore, since the parallelogram distortion shown in FIG. 2 can also be corrected with this correction signal C _A , both the upper and lower pink distortion distortion and the parallelogram distortion can be corrected simultaneously with this correction signal C _A.

This correction signal C _A is superimposed on the vertical sawtooth signal _TV in the adder 12 as shown in FIG. 6, and its combined output C _O (FIG. 7F) is supplied to the vertical output circuit 13.

The variable phase shifter 4 described above is mainly used to adjust the amount of correction of the parallelogram distortion S _B.
The correction amount is generally adjusted using the horizontal sawtooth signal T _H
However, when correcting the upper and lower pink distortion S _C at the same time as in the present invention, by adjusting the amplitude, the composite signal C _DE shown in FIG. 7C is corrected. The peak point of shifts to the left or right. This peak point shift can also be performed by changing the phase of the horizontal sawtooth signal T _H , so in this embodiment, the correction amount is adjusted by adjusting the phase instead of the amplitude. This is the case.

When it is desired to adjust the correction amount of the upper and lower pink distortion S _C and the correction amount of the parallelogram distortion S _B independently, the addition ratio of the operational amplifier 9 may be manually adjusted from the outside, for example.

As explained above, according to the present invention, X-
Upper and lower pink distortion S _C is a symmetric screen distortion with respect to the X′ axis, and parallelogram distortion is an asymmetric screen distortion.
Since S and _B can be corrected purely electronically at the same time, screen distortion can be corrected without mechanical adjustment even if the horizontal and vertical deflection coils are not installed accurately or orthogonally. Therefore, the adjustment for correcting screen distortion is easy, the adjustment time can be shortened, and the adjustment accuracy is high.

Furthermore, when configured as shown in FIG. 6, the circuit configuration can be simpler than when configured in principle. That is, in order to correct the screen distortion S _B shown in FIG. 2, first a correction signal C _D for correcting the trapezoidal distortion S _D shown in FIG _. In order to apply this correction signal C _D to a constant level, this correction signal C D is further subjected to balance modulation to form a correction signal in which the phase of the horizontal sawtooth signal T _H is constant. Then, in order to correct the vertical pink distortion S _C shown in Fig. 3, a correction signal C _C (Fig. 5 A) is formed by a balance modulator, and this is combined with the previous correction signal to finally obtain the correction signal C C (Fig. 5 A). A correction signal C _A shown in FIG. 7E is formed.

Therefore, while this basic configuration requires at least three balance modulators, the configuration shown in FIG. 6 can achieve the same effect by using only two balance modulators. It is possible to simplify the configuration.

[Brief explanation of the drawing]

1 to 4 are explanatory diagrams of screen distortion, FIG. 5 is an explanatory diagram of a screen distortion correction signal, FIG. 6 is a system diagram showing an example of the screen distortion correction circuit according to the present invention, and FIG. FIG. 3 is a waveform diagram for explaining the operation. 5 and 6 are sawtooth wave signal T _H and _TV forming circuits;
7 and 11 are balance modulators, 8 is an integration circuit, 9 is an adder, 13 is a vertical output circuit, C _A is a correction signal, and C _P is a horizontal parabolic wave signal.

Claims (1)

[Claims] The horizontal sawtooth signal is modulated by the vertical sawtooth signal and then added to the horizontal parabolic wave signal, and the added output is modulated by the vertical sawtooth signal and supplied to the vertical output circuit to generate upper and lower pink tension distortion. This screen distortion correction circuit corrects both parallelogram distortion and parallelogram distortion at the same time.