JPS58133091A - Automatic degaussing device - Google Patents

Abstract

PURPOSE:To perform an automatic degaussing with opening of a main power source switch, by detecting the lowering of a DC voltage by opening of the main power source switch to generate a control signal and making a unidirectional element such as a thyristor conductive to generate a damping oscillation power. CONSTITUTION:A series circuit consisting of resistances (Rs) 2 and 3 is connected between a DC power source 1 and the earth, and the voltage dividing point of the series circuit is connected to the base of a transistor (TR) 4. The emitter of the TR4 is not only connected to the power source 1 through an R5 but also is grounded through a Zener diode 6 and a capacitor (C) 7. The coolector of the TR4 is not only grounded through an R8 but also is connected to a C10, which has one end grounded, through an R9. A pulse obtained in a fly-back transformer is applied to a terminal 11 and is applied to a series resonance circuit consisting of a C15, a degaussing coil 16, and an R17 through a diode D12. A thyristor element 18, to which the terminal voltage of the C10 is given as a control voltage, and a D19 are connected in parallel to the series resonance circuit with opposite polarities. Thus, the automatic degaussing is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic degaussing device for a color television receiver, and an automatic degaussing device that can perform degaussing using a main power switch without using a special degaussing switch. An embodiment of the present invention will be described below with reference to the drawings.

A degaussing circuit that uses DC power supply voltage can be constructed by charging a capacitor while the color television receiver is operating, then switching the degaussing switch and connecting the capacitor in parallel to a series resonant circuit that includes a degaussing coil. A damped oscillating current is passed through the degaussing coil. This degaussing circuit requires a special degaussing circuit. Therefore, the present invention aims to provide an automatic degaussing device in which a degaussing switch is also used as a main power source, and embodiments of the present invention will be described below with reference to the drawings.

As shown in Figure 1, there is a resistor 2 between the DC power supply terminal 1 and the ground.
and 3 are connected in series, and the voltage dividing point of this series circuit is connected to the base of transistor 4.

The emitter of this transistor 4 is connected to the terminal 1 through a resistor 6.
and is grounded via a Zener diode 6 and a capacitor 7.

A constant voltage is applied to the emitter of the transistor 4 by the Zener diode 6.

The collector of the transistor 4 is grounded via a resistor 8, and the capacitor 1 has one end grounded via a resistor 9.
0 is connected to the other end. When the main power switch is opened and there is no voltage at terminal 1, the pace voltage of transistor 4 decreases and transistor 4 becomes conductive. Then, a voltage is generated across the resistor 8, and this voltage is used as a control voltage.

On the other hand, the pulse at terminal 11, which is applied to the flyback transformer, is rectified by diode 12, rectified by capacitor 13, and the obtained voltage is passed through resistor 14 to capacitor 16, degaussing coil 16, and resistor 17. at one end of the series resonant circuit.

The other end of this series resonant circuit is grounded. A unidirectional switching element 18 with a control terminal such as a thyristor and a diode 19 are connected in parallel to this series resonant circuit with mutually opposite polarities.

When the mains switch is closed, a pulse is present at the terminal 11 and the capacitor 16 is charged by the DC voltage rectified by the diode 12. At this time, both unidirectional elements 18 and 19 are in the off state.

When the main power switch is opened, the transistor 4 is turned on as described above, and a voltage is generated across the resistor 8, which is applied as a control voltage to the gate of the thyristor 18. Then, thyristor 1B is turned on, and the charge in capacitor 16 is transferred to thyristor 1.
8, resistance 17, and demagnetizing coil/L/16 loop.

Next, the energy of the degaussing coil 16 flows as a current through the loop of the resistor 17, diode 19, and capacitor 16, and this process is repeated to produce a damped oscillating current as shown in FIG.

FIG. 3 shows another embodiment, in which a signal generating circuit using a comparator using an operational amplifier 2o is provided in place of the transistor 4, and a bidirectional thyristor 21 is provided in place of the thyristor 18 and diode 19.

As described above, according to the present invention, a control signal is generated by detecting a drop in DC voltage due to opening of the main power switch,
Since this control signal conducts a unidirectional element such as a thyristor and generates a damped oscillating current, there is no need to install and operate a special degaussing switch, and demagnetization is automatically performed by opening the main power supply switch. It is of high industrial value.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an automatic demagnetizer according to one embodiment of the present invention, FIG. 2 is a circuit diagram of an automatic demagnetizer according to another embodiment of the invention, and FIG. 3 is a waveform diagram for explaining the same device. 1...DC power supply terminal, 2, 3...Resistor, 4...Transistor, 6...Zener diode, 18...Thyristor, 19...
...transistor, 16... degaussing coil,
15... Capacitor, 17... Resistor,
11...Pulse application terminal, 21...Bidirectional sirisk. Name of agent: Patent attorney Toshio Nakao and one other person Toshio
Satoshi + '1 disappearance 545-

Claims (1)

[Claims] A series resonance system including a signal generation circuit that generates a control signal when the DC voltage decreases when the main power switch is opened, and a capacitor and a degaussing coil between the DC power terminal and ground, the voltage of which becomes 0 when the main power switch is opened. A circuit is provided, a unidirectional switching element with a control terminal is connected in parallel to this series resonant circuit, and a unidirectional element with a polarity opposite to this switching element is connected in parallel, and the output of the signal generation circuit is connected to the control terminal. An automatic degaussing device characterized by adding: