JPS5992690A - Degaussing circuit - Google Patents

Abstract

PURPOSE:To eliminate contacts of the switch part of a degaussing circuit and to reduce the cost of the switch part greatly by connecting a posistor, degaussing coil, and triac in series between a power supply path and the ground. CONSTITUTION:One terminal of the serial circuit of the posistor 4 and demagnetizing coil 5 is connected to the current supply path 2 and the triac 20 is connected to the other terminal. The gate of the triac 20 is triggered by the voltage obtained by rectifying and smoothing pulses from the teriary winding of a flyback transformer 21. When a power source switch 8 is turned on at this time, the terminal voltage across a capacitor 24 rises excessively and the triac 20 turns on possibly in its rising; a means 25 of supplying a trigger to the gate of the triac 20 after the potential at a point A rises up to a specific value is provided for the prevention.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention is applicable to devices where at least a portion of the device may be undesirably magnetized due to the influence of earth's magnetism, etc., which may adversely affect the operation of the device. The present invention relates to a degaussing circuit for electrical equipment, such as a television receiver, which needs to be degaussed at the same time as a power switch in order to eliminate inconveniences.

(b) Prior Art As shown in Fig. 1, conventionally the socket (1) is connected to the
An electromagnetic relay (3), a POSISTOR (4), and a degaussing coil (5) between the power supply path (2) and ground? Connect the relay coil (6) and drive transistor i71kM between the DC power supply (10B) and the ground, and turn on the television receiver's power switch (8) instantly to connect the microcomputer (9). Output terminal ■O1t is not in high level state, is this high level voltage? The voltage is divided by the resistor ullu2 and added to the base of the drive transistor (7), and the drive transistor [7]t is turned on, and the electromagnetic relay (3)? When turned on, a transformer current flows from the power supply path (2) to the series path of the electromagnetic relay switch U, POSISTOR 14), and degaussing coil 15) to perform demagnetization. POSISTOR+4+r
t.

There? The heat generated by the flowing current instantly increases the resistance value, and the current... attenuate it.

In FIG. 1, 141 is a switch circuit that is sterilized by the voltage generated at the output terminal 1101 of the microcomputer (9), and is equipped with a switch 51 and a transistor (16I), and when in the on state. A DC voltage of 100V is supplied to the load surface.A rectifier diode and a smoothing capacitor for AC10[IVY rectification are provided from the 0&(lαri power supply path (2)).

(c) Purpose of the Invention The conventional degaussing circuit described above uses an electromagnetic relay as a mechanical switch, resulting in a large size and high cost, and a problem of reduced reliability due to long-term use.

In view of this point, the present invention proposes an effective degaussing circuit that does not use an electromagnetic relay.

2) Configuration of the present invention A POSISTOR, a degaussing coil, and a TRIAC are connected in series between the power supply path and the ground, and after the positive DC voltage generated in the electrical equipment reaches the magnitude of two, or the blood flow voltage is Shortened the rise time and made the mark appear on the gate of the try book.

(e) Examples of the present invention Is this invention? Is the symbol A the same as that in Figure 1 in Figure 2 and below? Add and explain? Omitted.

In the present invention, as shown in FIG. 2, the current supply path (2) is connected to one end of a series circuit of a POSISTOR (4) and a degaussing coil (5). In addition to connecting the series circuit @t triac f2P
a: 'Valve connected to ground. And the gate trigger of the triac explosion is the load α7 as a TV circuit.
), the pulse sound obtained from the sixth winding of the flyback transformer (ZD) is rectified by a diode (e), smoothed by a capacitor (about 500 μF), and the i6
This is done using a voltage from a power supply that generates a DC voltage of v. The DC voltage from the 16V power supply is used as a power supply for the IC in the load (In).In addition, when applying a positive DC voltage obtained from such a load [171] to trigger the gate. , the following problems arise.

In other words, does the triac have a positive DC voltage on its gate? In addition, when triggering, there is a drawback that when the trigger current is small, only the positive part of the AC voltage applied between the first and second electrodes or only the negative part of Fi turns on. 8) Since the voltage across the capacitor rises transiently after it is turned on until it reaches the predetermined value of 16V, it tends to occur during startup. Therefore,
A problem like this? In order to overcome this problem, see tf in Figure 2 (after the potential at point A1 rises to a certain value, the means for giving a trigger to the gate of the triac wire)? It is set up. Note that the above-mentioned problem does not occur when the triac □□□ triggers the gate with a negative DC voltage. The circuit to be formed must be specially provided.

Is Fig. 6 the means Of9 in Fig. 2? A concrete example of the circuit is shown.Here, voltage dividing resistors (R1) (R2) are Y-connected between the line wire connected to point (A) in Fig. 2 and the ground, and an NPN) transistor ( TR1) collector, emitter path and resistor (R3) y are connected, and NT'
lJ The base of the transistor (TR1) is connected to the voltage dividing resistor (R
+) (R2) connection middle point (a) Pressure connected. In addition, triac no 0) game) UNPN) transistor (TR
It is connected to the emitter of I).

In FIG. 6, the potential at the connection center point (A) 1jNPN) is not turned on until the potential of the line (4) reaches a predetermined potential, and when the potential of the line reaches the predetermined potential, the NPN) Turn on transistor (TR1) Y. Therefore, since the triac (4) is not triggered by a small gate current, it does not occur that the triac (4) conducts only at the positive and negative sides of the alternating current applied between the first and second poles.

In the above-mentioned diagrams (Figures 2 and 6), the above-mentioned inconvenience is avoided by not applying IJ (in the range of the small DC voltage applied to the gate of the triac). Speed up the voltage rise time,
The aforementioned disadvantages can also be substantially avoided by reducing the time during which a small trigger voltage is applied to the gate of the triac.

Based on this idea, in Figure 4, a resistor (R4) and a capacitor (c) are connected between the terminal wire connected to point (A) in Figure 2 and the ground.
Connect l) and connect the capacitor (C1)) 91
Voltage generated at 1? I am trying to apply it to the gate of triac Cα. For example, 100μF for capacitor (C1)
Each resistor (R4) is set to about 1000, and its photoelectric time constant is made smaller. (While it takes about 1 second for the potential at point M to rise from O to 16V, the voltage on the hot side of the capacitor (C1) rises from Ov to a predetermined voltage (a voltage that does not cause the above problems in the trybook). It will take much less time.

Figure 5 shows that after demagnetization is complete, the TRIAC is completely turned off and there is no residual demagnetization current. It is configured to make it zero. That is, in FIG. 5, a voltage dividing resistor (R5) (R1) is connected between the terminal connected to point (A) in FIG. R7),
PNP) transistor (TR2) x, collector path and first:l nf7 (C1) are connected in series,
Further, a second capacitor (C2) is connected in parallel with the resistor (R6), a discharging diode (Dl) of the second capacitor (C2) is connected in parallel with the resistor (R5), and the PNP transistor (
The base of TR2) is connected so that the voltage generated on the hot side of the A2 capacitor (02) is applied, and the voltage generated on the hot side of the first capacitor (C1) is applied to the gate of the TRIACK (20). It is configured like this.

According to the circuit shown in FIG. 5, the transistor (1PNP) (TR2) is turned on until the voltage at the terminal (a) rises to a predetermined value, and the first capacitor (,c+)y is photoelectrically charged. At this time, the same effect as shown in FIG. 4 occurs due to the time constant of the resistor (R7) and the first capacitor (C1).

The triac circle becomes conductive and a demagnetizing operation is performed.

In such a state, when the potential of terminal (A) reaches a predetermined value, PN
P) Transistor (TR2)ri turns off. Therefore, the first
The capacitor (C1) is not charged and the remaining first
The triac (20) is fixed off by consuming the charge of the capacitor (C1) as a gate trigger current. In this manner, in FIG. 5, the triac is turned off after the demagnetization operation is performed, so that no residual demagnetization current flows, which is effective. In addition, PNP) transistor (TR
2) Off ffl, resistor in parallel with the first capacitor (C1) to accelerate the discharge Y of the first capacitor (C1)? Connect MoJ: <, 9NPN) transistor with a collateral electrode connected to the hot side of the 1A2 capacitor (C2)? It may be connected in parallel with the first capacitor (C1) [7].

(f) Effects of the present invention In the present invention, since an inexpensive and small triac is used for the electromagnetic relay, the cost of the switch part of the degaussing circuit is greatly reduced, and the reliability is also improved by making the switch non-dischargeable. do. ,
Furthermore, since electromagnetic relays do not produce unpleasant noises, they are useful for improving the image of equipment such as color television receivers, which are almost entirely electronically switched. Friend, in the present invention, the operational disadvantages that may occur when using the TRIAC 2 are avoided by taking additional measures to the gated IJ signal system, so the extremely suitable demagnetization by the TRIAC is achieved. This has the effect of realizing current control wholesale.

[Brief explanation of the drawing]

Is Figure 1 a conventional degaussing circuit? FIG. Is Figure 2 the invention? FIG. 6 is a circuit diagram of the implemented degaussing circuit, and is a diagram specifically showing the main part thereof. FIG. 4 is a circuit diagram of another embodiment of the present invention. FIG. 5 is a circuit diagram of still another embodiment of the present invention. (2)...Power supply i@path, (4)...POSISTOR, (
5)... Degaussing coil, (8)... Power switch, ■
...Trybook, (C) Means for applying the voltage after it reaches a predetermined level, (C1)...Capacitor for shortening the voltage rise. Is it 1?

Claims (1)

[Claims] 11) Connecting one end of a series circuit of a POSISTOR and a degaussing coil to the power supply path of an electrical device, and the other end of the series circuit? 2. Power switch of electrical equipment coupled to ground via triac? The triac is characterized by being provided with means for applying the positive voltage generated in the electric device when it is turned on to the gate of the triac after it reaches a predetermined level or after shortening the rise time of the voltage. Degaussing circuit. 121 11! Posistor and demagnetizer 1 in the power supply path of the equipment
One end of the series circuit is connected to the other end of the series circuit, and the other end of the series circuit is connected to ground via a triac, and the positive voltage generated in the electrical equipment when the power switch of the electrical equipment is turned on is connected to the triac. 1. A degaussing circuit comprising means for applying the voltage to the gate of the circuit and then automatically connecting or disconnecting the voltage to the gate.