JPS63206085A - Degaussing circuit for television receiver - Google Patents

Abstract

PURPOSE:To obtain the degaussing effect of a suitable cathode ray tube in any case by switching a first degaussing element and a second degaussing element in accordance with the size of an AC input voltage, and making variable a current flowing in a degaussing coil. CONSTITUTION:For example, when the input voltage of an AC socket 1 is >=AC 155V, a transistor 27 is turned off and a two way thyrister 37 is turned off. Consequently, a degaussing coil 41 is connected with a degaussing element 39 only and the cathode ray tube is degaussed by a damped oscillation current flowing into the degaussing coil 41 determined by the degaussing coil 41 and the degaussing element 39 and an AC voltage. When the AC input voltage of the AC socket 1 is <=150V, the transistor 27 is turned on, the two way thyrister 37 is turned on and the degaussing coil 41 and a degaussing element 38 are connected between AC input terminals. As the result, in the same way, the damped oscillation current flows at the degaussing coil 41 and the coathode ray tube is degaussed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is applicable to AC power supplies that have a wide voltage range (AC
80vNAC3oOv) relates to a degaussing circuit in a TV set.

Conventional technology Currently, regional TeId such as the Middle East, Indonesia, Brazil, etc.
Commercial AC aTIL source A C11o V, A C22
Because it is mixed with 0V, it is safe and serviceable.

Switch with AC30V-Ac3ooVt! There is a demand for television receivers that operate stably without any problems, and many of them are actually on the market.

Figure l@2 shows that the conventional commercial AC power supply is ACsOV~300V.
This is a power supply circuit and degaussing circuit for television gene receivers that operate stably up to 1 is AC socket, 2 is switch, 3
is Fuse, 4,11.12゜16.17,19,21
．． 22, 25, 28, 30° 36 is a fixed resistor, 9, 1
0, 15, 23.26 are capacitors, 5.6, 7, 8
．． 14 is a diode, and 13 is a bidirectional thyristor. Further, 20 and 27 are transistors, and 18 and 24 are Zener diodes. 40 is a converter power supply circuit. 29 is the television receiver load (signal system).

(deflection system, etc.), 31 is a demagnetizing element C (negative resistor), 32
is a demagnetizing coil.

Connect commercial AC power (AC80V~30o) from AC socket 1.
v) is input, switch 2. Fuse 3, fixed resistor 4. Through diodes 6-8 and capacitor 9.10
It is added to the rectifier circuit consisting of.

The elements 13 to 28 and the resistor 3o stabilize the rectifier circuit from AC30V to AC300V.

However, in the degaussing circuit, AC80V-AC30
In order to properly demagnetize the cathode ray tube between 0V,
The cathode ray tube size is 20 inches class, and there are 3 degaussing coils.
Approximately 1400 AT is required for one loop winding. Also, the residual magnetic flux must be 2AT or less. this is,
This was determined from experimental values. Demagnetizing element 31
．． When an AC voltage is applied to the series circuit of the degaussing coil 32, a conventionally known operation occurs, and a damped oscillating current flows through the degaussing coil 32 to demagnetize the cathode ray tube.

Problem to be Solved by the Invention Here, in order to satisfy demagnetization of a 20-inch cathode ray tube with an AC voltage of 110 V, 1400 AT magnetic flux is required. Here, if the resistance of the demagnetizing element 31 is 6Ω, the number of turns of the demagnetizing coil 32 is approximately 63 turns. The resistance value at that time is approximately 6Ω. Calculating the magnetic flux from this: (11ox2r2)÷(a+5)X45 Cape 1400A
T and Naru. It is configured to switch between a double wave rectifier circuit and a voltage doubler double wave rectifier circuit depending on the AC 240v AC input voltage.

A broken line block A is a circuit for controlling the gate of the bidirectional thyristor 13. Converter power supply circuit 40
The stabilization range of the output voltage (DC 113V) is 210V to 400V as a DC input voltage, which is a converter power supply circuit that converts to an AC voltage of about 160V to 300V. Therefore, in order to stabilize the output voltage of the converter power supply circuit 40 between ACaoV and 300V, the bidirectional thyristor 13 is connected to the AC voltage 16oV so that the voltage of the converter power supply circuit 400 is 210v to 4oOv.
Switching near v, diodes 6 to 8. Block A is configured so that the rectifier circuit composed of capacitors 9 and 10 is switched to a single-wave voltage doubler circuit when the AC voltage is 150 V or less, and to a double-wave rectifier circuit when the ACl voltage is 5 esV or higher.

Block A operates in a conventionally known manner, and detailed description thereof will be omitted.

Therefore, in the case of the output voltage of the converter power supply circuit 4o, when the degaussing coil 32 is used, the magnetic flux is (240X
2ρ)÷(5+5)×46==3024AT, which is 2.16 times the proper degaussing, which causes the problem of beat of the cathode ray tube.

In addition, when the demagnetizing magnetic flux is set appropriately in AC2aOV, the resistance value of the demagnetizing element 31 is set to 18Ω, and the specifications of the demagnetizing coil 32 are as follows.If the demagnetizing magnetic flux is calculated using the above specifications, (240
X2r2)÷(166) X4ffi=1440
It becomes AT and satisfies the appropriate demagnetizing flux of the cathode ray tube, but
However, in the case of ACloV, the demagnetizing flux is calculated as (110X2r)÷(16+5)X45=659AT.

Appropriate demagnetizing magnetic flux for cathode ray tube 659/1400 X1■
Since there are only seven channels, there are various problems in that the cathode ray tube cannot be properly demagnetized.

In view of the above problems, the present invention provides an AC voltage of 80 to 300V.
The present invention provides a degaussing circuit for a television receiver, which can properly demagnetize a cathode ray tube during operation.

Means for Solving the Problems To achieve this objective, the degaussing circuit of the present invention comprises a first
．． The present invention is characterized in that a second demagnetizing element is provided, and the demagnetizing element is automatically switched and connected to the demagnetizing coil according to the magnitude of the AC input voltage.

According to the present invention, the first
By switching the degaussing element and the second degaussing element and varying the current flowing through the degaussing coil, an appropriate degaussing effect of the cathode ray tube can be obtained in either case.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a power supply circuit and a degaussing circuit of a television receiver according to an embodiment of the present invention.

In the figure, 1 is an AC socket, 2 is a switch, 3 is a fuse, 4, 11.12, 16, 17, 19° 21.22, 2
5.2B, 30.36 is a fixed resistor, 9, 10.15
．． 23.26 is a capacitor, 5 m 6 * 7 #
8 @ 14 is a diode, 13 is a bidirectional thyristor, 20.27 is a transistor - 118, 24 is a Zener diode, 40 is a converter power supply circuit, 29 is a television receiver load (signal system, deflection system, etc.) The above configuration is similar to the configuration shown in FIG. 33.34 is a reverse current prevention diode, 38.36 is a fixed resistor, 37
is a bidirectional thyristor for switching the degaussing element,
Demagnetizing elements 38 and 39 have different resistance values, and here, for example, the resistance value of the demagnetizing element 39 is much larger than that of the demagnetizing element 38.

41 is a demagnetizing coil.

The normal operation is the same as that of the conventional example, and here, one degaussing element switching circuit of the present invention will be explained.

Block Δ is the AC socket input voltage, below AC150V, transistor 27 is turned off, AC1ss
When the voltage is higher than V, the transistor 27 is turned on. This operation is conventionally known, so its explanation will be omitted.

, Here, the input voltage of AC socket 1 is AC1asV
In the above case, the transistor 27 is turned off and the collector of the transistor 27 becomes the diode 34. Since it is connected to the gate of the bidirectional thyristor 37 via the fixed resistor 36, the bidirectional thyristor 37 is turned off, and the degaussing coil 41 is connected only to the degaussing element 39.
It is determined by the demagnetizing coil 41, the demagnetizing element 39, and the AC voltage. The cathode ray tube is demagnetized by the damped oscillating current flowing through the demagnetizing coil 41.

Further, when the AC input voltage of the AC socket 1 is 150V or less, the transistor 27 of the block A is turned on. Since the collector of the transistor 27 is connected to the fixed resistor 36 via the cathode of the diode 34 and to the gate of the bidirectional thyristor 37, the bidirectional thyristor 37 is turned on and the degaussing coil 41 and the degaussing element 38 are turned on. is connected between the AC input terminals. As a result, a damped oscillating current flows through the demagnetizing coil 41 in the same manner as described above, and the cathode ray tube is demagnetized.

Here, the demagnetizing element 39 is also connected to the demagnetizing coil 41, but the resistance values of the demagnetizing element 39 and demagnetizing element 38 are three times larger than that of the demagnetizing element 39, so the demagnetizing current is It is determined by element 38.

Therefore, the specific specifications of the degaussing coil are as follows: number of turns: 46 turns, resistance: 6Ω, resistance of the demagnetizing element 38: 6Ω.

Calculate how much demagnetizing magnetic flux will be at each AC input voltage when the resistance value of the demagnetizing element 39 is 18Ω.

ACl 10V (7) --- (110VX2
r2 )÷(5+5)X46:141 esAT For AC240V...--(240VX2r2'
l ÷ (1B+-5) also satisfies adequate demagnetization.

Effects of the Invention As described above, according to the present invention, by simply adding a simple circuit, cathode ray tubes can be properly demagnetized in areas where ACl 10V and AC 240V are mixed, and the price of the degaussing coil can be reduced. This makes it possible to reduce the price of television receivers, and its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a degaussing circuit of a television receiver according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of a power supply circuit and a degaussing circuit of a conventional example. Block A... Voltage detection switch circuit, 37.
...Bidirectional thyristor, 39...1st
Demagnetizing element. 38... Second demagnetizing element, 41... Demagnetizing coil.

Claims (1)

[Claims] A second degaussing element, a switch circuit, and a series circuit are connected in parallel with the first degaussing element, and this parallel circuit is connected in series with the degaussing coil to an AC power source, and a detection output of a detection circuit that detects the voltage of the AC power source. 1. A degaussing circuit for a television receiver, characterized in that the switch circuit is opened and closed depending on the situation.