JPS63164761A - Vertical deflection circuit - Google Patents

Abstract

PURPOSE:To shorten leading time at the application of power by providing a Zener diode connected in forward direction toward the positive power supply polarity from the high potential side of a smoothing capacitor constituting a DC feedback circuit. CONSTITUTION:The Zener diode 3 connected in the forward direction toward the positive polarity side of the smoothing capacitor C1 constituting the DC feedback circuit 2 form its high potential point. The voltage Va of the positive power supply connected to the capacitor C1 via the Zener diode 3 is selected in the relation of +Va<Vz+Vf, where Vz is the breakdown voltage of the Zener diode 3 and Vf is the voltage of the smoothing capacitor constituting the DC feedback circuit 2 during normal operation. Since a voltage (Va-Vz) is applied directly to the smoothing capacitor C1 as soon as the power supply is applied, the smoothing capacitor C1 is charged rapidly till the breakdown voltage Vz of the Zener diode and charged by a feedback signal only while the Zener diode 3 is cut off and its voltage reaches the voltage Vf. Thus, the leading time is shortened remarkably.

Description

[Detailed Description of the Invention] [Summary] In a vertical deflection circuit having a DC feedback circuit, the vertical deflection Reduced circuit startup time.

[Industrial application field]

The present invention relates to a vertical deflection circuit provided in a CR7 display device.

A vertical deflection circuit is a device that generates a vertical deflection current from a sawtooth voltage synchronized with a vertical synchronization signal, and is particularly used in graphic display devices.

Great importance is placed on reducing distortion of displayed graphics.

[Conventional technology]

A configuration diagram of a conventional example is shown in FIG. In fig.

Reference numeral 1 denotes an amplifier circuit including a voltage amplification section 11 and a current amplification section 12.

2 is a DC feedback circuit consisting of resistors R1 and R2 and a capacitor CI.

1 is a vertical deflection coil (Lv), and 5 is an AC feedback circuit.

[Problem that the invention seeks to solve]

In the vertical deflection circuit with the above configuration, when the power is turned on.

There is a problem in that vertical deflection is not performed for about 0.5 to 1 second until the smoothing capacitor C1 included in the DC feedback circuit 2 finishes charging and the voltage Vf in this part reaches a predetermined value. .

In addition, to shorten this time, resistor R1 and capacitor C
Although it is possible to reduce the value of the time constant determined by 1, this is not preferable in terms of obtaining a desired feedback signal.

That is, an object of the present invention is to shorten the rise time when power is turned on without reducing the time constant of the DC feedback circuit.

[Means for solving problems]

The vertical deflection circuit according to the present invention is shown in the principle diagram of FIG.

an amplifier circuit 1 that amplifies a sawtooth wave synchronized with a vertical synchronization signal and generates a current to be supplied to a vertical deflection coil;

a DC feedback circuit 2 that feeds back a DC signal from the vertical deflection coil side to the input side of the sawtooth wave;

A Zener diode 3 is connected in a forward direction from the high potential side of the smoothing capacitor constituting the DC feedback circuit 2 to the positive power supply Va side.

[Effect]

The smoothing capacitor provided in the DC feedback circuit 2 is charged via a Zener diode 3 using another power source until its breakdown voltage is reached.

〔Example〕

Second, a configuration diagram of the embodiment is shown. The reference numerals in the drawings are the same as those described with reference to FIGS. 1 and 3, so their explanation will be omitted.

The voltage Va of the positive power supply connected to the capacitor C1 through the Zener diode 3 is when the breakdown voltage of the Zener diode 3 is Vz and the voltage during normal operation of the smoothing capacitor constituting the DC feedback circuit 2 is Vf.

+ Va < Vz + Vf Use values that are in the relationship.

At the same time as the power is turned on, the smoothing capacitor C1 (
A voltage of Va - Vz) is applied directly.

Therefore, the smoothing capacitor C1 is rapidly charged until it reaches the breakdown voltage of the Zener diode.

Charging is performed by the feedback signal only from the time when the Zener diode 3 cants off until it reaches vf.

As a result, the time it takes for the voltage on the high potential side of the smoothing capacitor to reach its normal value after turning on the power is 0.1 to 0.
．． It can be shortened to about 2 seconds.

〔Effect of the invention〕

As explained above, in the vertical deflection circuit of the present invention, the rise time can be significantly shortened simply by adding one Zener diode.

Note that the addition of the Zener diode does not have any adverse effects on circuit operation or other aspects.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention. FIG. 2 is a configuration diagram of the embodiment. FIG. 3 is a configuration diagram of a conventional example. In the figure. 1 is an amplifier circuit, 2 is a DC feedback circuit. 3 is a Zener diode. 4 represents a deflection coil, and 5 represents an AC feedback circuit.

Claims (1)

[Claims] An amplifier circuit (1) that amplifies a sawtooth wave synchronized with a vertical synchronization signal to generate a current to be supplied to a vertical deflection coil, and a DC signal is supplied from the vertical deflection coil side to the input side of the sawtooth wave. DC feedback circuit (2) to feed back and DC feedback circuit (2)
) and a Zener diode (3) connected in a forward direction from the high potential side to the positive power supply side of the smoothing capacitor forming the smoothing capacitor (3).