JPH059083U - Pincushion distortion correction circuit - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a pincushion distortion correction circuit that eliminates the difference in pincushion distortion correction amount that occurs when switching to a broadcasting system having different vertical scanning frequencies. [Structure] A vertical saw wave frequency is discriminated between a vertical saw wave generation circuit and a correction voltage generation circuit. A vertical frequency automatic discrimination circuit and a switching circuit which is switched by the vertical frequency automatic discrimination circuit and the amplitude of the vertical saw wave wave are corrected. An amplitude control circuit is inserted.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a pincushion distortion correction circuit, and more particularly to a pincushion distortion correction circuit suitable for correcting left and right pincushion distortion generated on a screen due to a difference in broadcasting system.

[0002]

[Prior art]

 As a conventional pincushion distortion correction circuit, a structure as shown in FIG. 2 has been provided.

In the figure, 10 is a vertical sawtooth wave generation circuit, 11 is a correction voltage generation circuit, and 12 is a horizontal deflection circuit.

As for the configuration and operation of the block, the vertical sawtooth wave generated by the vertical sawtooth wave generation circuit 10 is added to the correction voltage generation circuit 11, and integrated by this correction voltage generation circuit 11 to output a parabolic correction voltage. Then, the horizontal deflection current output from the horizontal deflection circuit 12 and flowing in the horizontal deflection coil DY is amplitude-modulated to correct the pincushion distortion occurring on the left and right of the screen.

Then, as the vertical scanning frequency changes to 50 Hz and 60 Hz due to the difference in the broadcasting system, the vertical sawtooth wave that is the input of the correction voltage generating circuit 11 also changes, and the pincushion distortion at each frequency of 50 Hz and 60 Hz It was supposed to correct the pincushion distortion in.

[0006]

[Problems to be solved by the device]

 However, in the conventional pincushion distortion correction circuit, the correction voltage generation circuit 11 in FIG. 2 does not necessarily perform the amplitude correction because the amplitude is not necessarily the same when the frequency of the vertical sawtooth wave input is 50 Hz and 60 Hz. However, there is a drawback in that it is not possible to output the correction voltage for the pincushion distortion.

The present invention has been made in view of the above points, and the purpose thereof is to solve the drawbacks of the conventional example, and to obtain the best correction voltage even if the vertical sawtooth wave changes to 50 Hz and 60 Hz. An object of the present invention is to provide a pincushion distortion correction circuit that can be added to the horizontal deflection circuit.

[0008]

[Means for Solving the Problems]

 The pincushion distortion correction circuit of the present invention comprises a horizontal deflection circuit for scanning an electron beam horizontal deflection, a correction voltage generation circuit for outputting a parabolic correction voltage from a vertical sawtooth wave provided in the horizontal deflection circuit, and a correction voltage generation circuit. In a pincushion distortion correction circuit consisting of a vertical sawtooth wave generation circuit that generates a vertical sawtooth wave that is the input wave of the circuit, a vertical frequency automatic determination circuit that determines the frequency of the vertical sawtooth wave and the amplitude of the vertical sawtooth wave are controlled. And a switching circuit for switching whether the vertical sawtooth wave is applied to the correction voltage generation circuit directly or through the amplitude control circuit by the vertical frequency automatic discrimination circuit.

[0009]

[Action]

 According to this invention, a horizontal deflection circuit for scanning the electron beam horizontal deflection, a correction voltage generation circuit for outputting a parabolic correction voltage from a vertical sawtooth wave, which is provided in the horizontal deflection circuit, and an input of the correction voltage generation circuit. In a pincushion distortion correction circuit consisting of a vertical sawtooth wave generation circuit that generates a vertical sawtooth wave, a vertical frequency automatic determination circuit that determines the vertical sawtooth frequency and an amplitude control that controls the amplitude of the vertical sawtooth wave. Since it is composed of a circuit and a switching circuit that switches whether the vertical sawtooth wave is applied to the correction voltage generation circuit directly or through the amplitude control circuit by the vertical frequency automatic discrimination circuit, the vertical scanning frequency is different depending on the broadcasting system (for example, SECAM). Method, PAL method, 60Hz, NTSC method, 50Hz) So that it is also always the best pincushion distortion correction is switched to the broadcast system with a difference in frequency of the vertical sawtooth wave by controlling the amplitude of the direct sawtooth.

[0010]

【Example】

 An embodiment of a pincushion distortion correction circuit according to the present invention will be described with reference to FIG.

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.

In the figure, 1 is a vertical frequency automatic discrimination circuit, 2 is a switching circuit, 3 is an amplitude control circuit, 10 is a vertical sawtooth wave generation circuit, 11 is a correction voltage generation circuit, and 12 is a horizontal deflection circuit.

As a block configuration, the output of the vertical sawtooth wave generation circuit 10 is connected to the input of the switching circuit 2, one output of the switching circuit 2 is connected to the correction voltage generation circuit 11, and the other output Is connected to the amplitude control circuit 3, and the output of the amplitude control circuit 3 is connected to the correction voltage generation circuit 11.

As the operation of the block configured as described above, the vertical sawtooth wave generated by the vertical sawtooth wave generation circuit 10 outputs, for example, 50 Hz when receiving in the NTSC system, and the vertical sawtooth wave is added to the switching circuit 2. Be done.

On the other hand, the vertical frequency automatic control circuit 1 checks the frequency of the vertical sawtooth wave and, for example, when the frequency of the vertical sawtooth wave is 60 Hz, the vertical sawtooth wave has a characteristic smaller than that when the amplitude is 50 Hz. In the case of the wave generating circuit 10, a switching signal is output so as to switch the switching circuit 2 so that a vertical sawtooth wave is directly applied to the correction voltage generating circuit 11.

Further, when the vertical sawtooth wave generation circuit 10 outputs a vertical sawtooth wave of 50 Hz, the vertical frequency automatic discrimination circuit 1 outputs a signal for switching the switching circuit 2 so that the vertical sawtooth wave is added to the amplitude control circuit 3. Output.

When the vertical sawtooth wave starts to be applied to the amplitude control circuit 3, the amplitude control circuit 3 controls the input vertical sawtooth wave to have the same amplitude as that of the vertical sawtooth wave of 60 Hz so as to obtain a correction voltage. Output to the generation circuit 11.

By performing the above-described operation, it becomes possible to eliminate the difference in amplitude due to the difference in frequency of the vertical sawtooth wave and to apply the parabolic correction voltage of the same amplitude to the horizontal deflection circuit. .

Therefore, even if the broadcasting system changes, the same amount of pincushion distortion on the screen is corrected.

In the embodiment, the switching circuit 2 is switched to the amplitude control circuit 3 side when the output signal of the vertical frequency automatic discrimination circuit 1 has a vertical sawtooth wave frequency of 50 Hz with a large amplitude. At this time, the amplitude control circuit 3 can be switched to the amplitude control circuit 3 so as to match the amplitude at 50 Hz.

[0021]

[Effect of the device]

 The pincushion distortion correction circuit according to this invention has the following effects because it is configured as described above.

There is an effect that it is possible to correct a change in the pincushion distortion rate that occurs at the time of video switching when the video system has a vertical frequency of 50 Hz when the broadcasting system is NTSC and at a vertical frequency of 60 Hz when the video is PAL or SECAM.

Moreover, it has a feature that it is easy to implement because it has only an additional circuit without changing the method for correcting the pincushion distortion.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention.

FIG. 2 is a configuration block diagram of a conventional example.

[Explanation of symbols]

 1 Vertical frequency automatic discrimination circuit 2 Switching circuit 3 Amplitude control circuit 10 Vertical sawtooth wave generation circuit 11 Correction voltage generation circuit 12 Horizontal deflection circuit

Claims (1)

Claims for utility model registration: 1. A horizontal deflection circuit for scanning an electron beam horizontal deflection; and a correction voltage generation circuit provided in the horizontal deflection circuit for outputting a parabolic correction voltage from a vertical sawtooth wave. In a pincushion distortion correction circuit consisting of a vertical sawtooth wave generation circuit that generates a vertical sawtooth wave that is an input wave of a correction voltage generation circuit, a vertical frequency automatic determination circuit that determines the frequency of the vertical sawtooth wave and the amplitude of the vertical sawtooth wave. A pincushion distortion characterized by comprising an amplitude control circuit for controlling the above, and a switching circuit for switching whether a vertical sawtooth wave is applied to the correction voltage generating circuit directly by the vertical frequency automatic discrimination circuit or through the amplitude control circuit. Correction circuit.