JPH0453092Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a vertical deflection circuit for a cathode ray tube for two-dimensional screen display.

BACKGROUND ART An example of a conventional vertical deflection circuit will be explained with reference to FIG. In FIG. 4, sawtooth wave generation circuit 1
generates a sawtooth wave signal synchronized with the vertical synchronization signal of the video signal to be reproduced, and outputs the vertical output circuit 2.
supply to. The vertical output circuit 2 is a negative feedback amplifier that generates a vertical deflection current proportional to the sawtooth signal. This vertical deflection current is supplied to a series circuit including a vertical deflection coil 3, an S-shaped correction capacitor 4, and a current detection resistor 5 connected in series. The voltage applied to the current detection resistor 5 is fed back to the vertical output circuit 2 and used to suppress waveform distortion.

With this configuration, the electron beam of a cathode ray tube equipped with a face plate for two-dimensional screen display is deflected in the vertical direction, but when the anode voltage of the cathode ray tube fluctuates, the force that attracts the electron beam in the direction of the screen increases. As a result, a relative error occurs in the deflection angle of the electron beam, resulting in a problem that the linearity of the image in the vertical direction decreases.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a vertical deflection circuit capable of suppressing a decrease in linearity in the vertical direction of an image due to fluctuations in anode voltage.

In order to achieve the above object, the vertical deflection circuit of the present invention obtains a multiplication signal of a signal representing the variation of the anode voltage and a sawtooth wave signal, and superimposes this on the sawtooth wave signal to output the vertical output. The configuration is such that the power is supplied to the circuit.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to FIG. In the block circuit diagram shown in FIG. 1, parts corresponding to those in the block circuit diagram shown in FIG. 3 are given the same reference numerals, and explanations of these parts will be omitted.

The sawtooth wave signal from the sawtooth wave generation circuit 1 is supplied to one input terminal of each of the multiplication circuit 22 and the addition circuit 23. At the other input terminal of the multiplication circuit 22,
A detection signal proportional to the output of a high voltage generation circuit 6 that applies a high voltage to the anode of a cathode ray tube (not shown) is supplied by a resistive voltage divider circuit 21. The high voltage generating circuit 6 is constituted by, for example, a flyback transformer triggered by a horizontal output circuit and a rectifying and smoothing circuit for rectifying its output. Multiplication circuit 22
The output is set to a positive or negative value according to the sawtooth wave signal increasing from the negative level to the positive level, and the value of the detection signal is increased or decreased according to the amplitude of the sawtooth wave to obtain a multiplication signal. This multiplied signal is supplied to the other input terminal of the adder circuit 23. The adder circuit 23 superimposes this multiplied signal on the sawtooth wave signal and supplies it to the vertical output circuit 2 at an appropriate level. The other configurations are similar to the conventional circuit.

Next, the operation of the circuit will be explained with reference to FIG. First, when the anode voltage fluctuates as shown in FIG.
2. Also, a sawtooth wave signal as shown in FIG. 2b is supplied to the multiplier circuit 22. As a result, the output of the multiplier circuit 22 has an output waveform as shown in FIG. 2c. This output is superimposed on the sawtooth wave signal to form a summed signal with an output waveform as shown in FIG. 2d, current amplified by the vertical output circuit 2, and supplied to the vertical deflection coil. Here, it is assumed that the left half of one wavelength of the sawtooth wave signal corresponds to the upper half from the center of the screen. In this region, when the anode voltage decreases, the attraction force of the electron beam toward the screen decreases, and the electron beam is relatively deflected toward the upper side of the screen. Correspondingly, since the amplitude of the addition signal decreases in the positive direction, the attraction force of the electron beam toward the upper side of the screen by the vertical coil decreases, and the deflection angle of the electron beam is maintained in a predetermined direction. Further, when the anode voltage decreases in a region corresponding to the lower half from the center of the screen, the amplitude of the addition signal decreases in the negative direction, so that the deflection direction of the electron beam is maintained in a predetermined direction. Similarly, when the anode voltage increases, the deflection of the electron beam is maintained in a predetermined direction.

Another embodiment is shown in FIG. In the block circuit diagram shown in FIG. 3, parts corresponding to those in the block circuit diagram shown in FIG. 1 are given the same reference numerals.
Explanation of such portions will be omitted. In this example,
A subtraction circuit 23a is inserted into the feedback loop of the vertical output circuit 2, and the output of the multiplication circuit 22 is inverted and superimposed on the feedback signal. A sawtooth wave generating circuit 1 is connected to the positive input terminal of the vertical output circuit 2.
A sawtooth wave signal is supplied from the input terminal, while an inverted version of the multiplied signal is supplied to its negative feedback input terminal, and the output signal has a signal waveform as shown in FIG. 2d. In this case, vertical output circuit 2
It can be said that the negative feedback amplifier circuit also functions as a superimposing means. Therefore, it functions similarly to the embodiment of FIG. Note that since the feedback signal is a sawtooth wave, it is also possible to use this as an input signal to the multiplier circuit 22. The other configurations are similar to the embodiment shown in FIG.

In this way, a decrease in the vertical linearity of the image due to anode voltage fluctuations is suppressed, but since the multiplier circuit is used, there is an advantage that the overall circuit configuration is simplified.

Effects of the Invention As explained above, in the vertical deflection circuit of the present invention, a multiplier circuit is used to obtain a multiplied signal of a change in the anode voltage of a cathode ray tube and a sawtooth wave signal for vertical deflection, and this multiplied signal is Since the configuration is such that a correction current corresponding to the vertical deflection current is superimposed on the vertical deflection current, it is possible to suppress a decrease in vertical linearity of an image due to anode voltage fluctuation, which is preferable.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining the operation of the embodiment, and FIG. 3 is a block circuit diagram showing another embodiment. FIG. 4 is a block circuit diagram showing a conventional example. Explanation of symbols of main parts, 1... Sawtooth wave generation circuit, 2... Vertical output circuit, 3... Vertical deflection coil, 6... High voltage generation circuit, 22... Multiplier circuit, 2
3, 23a...Addition circuit.

Claims (1)

[Scope of utility model registration request] A vertical deflection circuit of a receiver that vertically deflects an electron beam of a cathode ray tube displaying a two-dimensional screen, the circuit comprising a sawtooth wave signal generating means for generating a sawtooth wave signal, the sawtooth wave signal and the cathode ray. a multiplier circuit that obtains a multiplied signal by multiplying the anode voltage of the tube by a signal proportional to the anode voltage of the tube; a superimposing means for superimposing the multiplied signal on the sawtooth wave signal; and a vertical deflection coil driven by the output of the superimposing means. A vertical deflection circuit comprising a vertical output circuit.