JP3211840B2 - Degaussing device and degaussing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a degaussing device used for removing magnetism of a cathode ray tube in a television receiver.

[0002]

2. Description of the Related Art In a cathode ray tube of a television receiver,
A degaussing device is used to prevent deterioration of purity due to magnetization. And on a television with an AC power supply,
The degaussing current for the degaussing is obtained directly from a commercial AC power supply.

On the other hand, in a television of a DC power supply specification, an alternating current for degaussing cannot be obtained as it is, and therefore, as shown in FIG.
At 60 V), a resonance circuit including a degaussing coil 1 and a capacitor 2 connected in parallel to the demagnetizing coil 1 is switched by a changeover switch 3 to obtain an alternating current as shown in FIG. Reference numeral 4 denotes a resistor inserted in series with the degaussing coil 1.

For example, the capacity of the capacitor 2 is set to 10 μF /
When the voltage is set to 160 V, the electric energy stored in the capacitor 2 is obtained by closing the changeover switch 3.
The resonance current of the resonance circuit including the degaussing coil 1 and the capacitor 2 flows as shown in FIG.
The vibration is attenuated from A to -5A as peak values.
Then, the CRT can be demagnetized by the magnetic field due to the alternatingly attenuated resonance current.

[0005]

However, such a conventional degaussing device has a unimagnetism, that is,
Since a DC voltage is applied to the degaussing coil 1 only in one direction, the level of the alternating resonance current is not balanced in the positive and negative directions as shown in FIG.
There were problems such as slight magnetization remaining in the cathode ray tube and insufficient correction of the purity deviation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and it is an object of the present invention to improve the imbalance between the positive and negative levels of the resonance current and greatly reduce the residual magnetism on the CRT. It is an object of the present invention to obtain a degaussing device capable of performing the following.

[0007]

A degaussing apparatus according to the present invention is connected to a DC power supply to form a first resonance circuit, a degaussing coil and a first capacitor, and connected to the DC power supply. A second capacitor forming a second resonance circuit together with the degaussing coil;
And a changeover switch for alternately changing the direction of the resonance current in the resonance circuit of (1), wherein the capacity of the second capacitor is set to approximately の of the capacity of the first capacitor. Further, in the degaussing method according to the present invention, the changeover switch in the degaussing device is switched so that the first capacitor is first connected to the degaussing coil so that a charging current of the first capacitor flows to the degaussing coil. Then, the second capacitor is connected to the degaussing coil, and the switching is performed such that the charging current of the second capacitor flows to the degaussing coil.

[0008]

According to the present invention, one of the first capacitor and the second capacitor emits electric energy by the changeover switch, and the other charges while the resonance current flows between the first capacitor and the second capacitor. In the degaussing coil, forward and reverse bipolar resonance currents flow in a balanced state as a whole, thereby greatly reducing the residual magnetization of the CRT.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a degaussing coil, and reference numerals 3a and 3b denote non-locking changeover switches, which are interlocked. 2a,
Reference numeral 2b denotes a first capacitor and a second capacitor connected in parallel to the degaussing coil 1 via the changeover switches 3a and 3b.

The degaussing coil 1 and the capacitor 2a
Constitutes a first resonance circuit 5a, and the degaussing coil 1 and the capacitor 2b constitute a second resonance circuit 5b. 4a,
4b is a resistor. Here, the changeover switches 3a and 3b alternately change the direction of the resonance current in the first resonance circuit 5a and the second resonance circuit 5b.

Next, the operation will be described. First, the changeover switches 3a and 3b are switched to the fixed contact side in the direction of arrow P. As a result, the first capacitor 2a, which has been charged with electric energy from the DC power supply, discharges the capacitor 2a, the changeover switch 3a, and the demagnetizing coil 1a.
In between, a resonant current that alternately attenuates as shown in FIG. 2 flows. Also, during this time, the second capacitor 2
b is charged.

On the other hand, when the changeover switches 3a and 3b are switched to the fixed contact side in the direction opposite to the direction of the arrow P, the capacitor 2b, the changeover switch 3b and the demagnetizing coil are discharged by discharging the second capacitor 2b. 3, a relatively low-level resonance current as shown in FIG. 3 flows in a polarity opposite to the above-described resonance current.

Therefore, for example, the first and second capacitors 2
Assuming that each of the capacitances a and 2b is 10 μF / 160V, when the changeover switches 3a and 3b are switched in the direction of the arrow P, a maximum of +13 A flows through the demagnetizing coil 1 in the forward direction, and the direction opposite to the direction of the arrow P is reversed. When the direction is switched, a maximum current of 8 A flows in the reverse direction.

As a result, the degaussing coil 1 as a whole
A well-balanced resonance current is supplied in the positive and negative directions while attenuating oscillation, and the well-balanced magnetic field from the degaussing coil V enables the degaussing of the cathode ray tube to be performed sufficiently efficiently, thereby avoiding a shift in purity. become. Note that the balance of the resonance current is determined by setting the capacity of the second capacitor 2b to approximately 1/2 of the capacity of the first capacitor.
By doing so, it becomes substantially appropriate. The degaussing coil 1
The time constant of the parallel circuit of the capacitor and the second capacitor 2b is 0.
Since this is 47 seconds, it is desirable that the on / off interval of the changeover switches 3a and 3b be about 1 second.

[0015]

As described above, according to the present invention, the degaussing coil and the first capacitor connected to the DC power supply to form the first resonance circuit, and the degaussing coil connected to the DC power supply and the degaussing coil are provided. A second capacitor forming a second resonance circuit;
Since the directions of the resonance currents in the resonance circuit and the second resonance circuit are alternately switched, the demagnetizing magnetic field based on these resonance currents can be balanced, and the magnetization of the CRT can be significantly reduced, and the deviation of the purity can be reduced. There is an effect that something that can be avoided almost completely is obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a degaussing device according to one embodiment of the present invention.

FIG. 2 is a timing chart illustrating a resonance current of the resonance circuit in FIG. 1;

FIG. 3 is a timing chart showing a resonance current of the resonance circuit in FIG. 1;

FIG. 4 is a circuit diagram showing a conventional degaussing device.

FIG. 5 is a timing chart illustrating a resonance current of the resonance circuit in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Degaussing coil 2a 1st capacitor 2b 2nd capacitor 3a, 3b Changeover switch 5a 1st resonance circuit 5b 2nd resonance circuit

Claims (2)

(57) [Claims] A demagnetizing coil and a first capacitor connected to a DC power supply to form a first resonance circuit; and a second degaussing coil connected to the DC power source and the degaussing coil.
A second capacitor that forms the resonance circuit of the above, and a changeover switch that alternately switches the direction of the resonance current in the first resonance circuit and the second resonance circuit,
The capacity of the second capacitor is changed to the capacity of the first capacitor.
A degaussing device characterized in that the capacitance is approximately １ ／ . 2. A first resonance circuit connected to a DC power supply to form a first resonance circuit.
A degaussing coil and a first capacitor connected to the DC power source, and a second degaussing coil together with the degaussing coil.
A second capacitor forming a resonance circuit of the first and second resonance circuits, and a resonance capacitor in the first resonance circuit and the second resonance circuit.
A changeover switch for alternately switching the flow direction,
The capacity of the second capacitor is changed to the capacity of the first capacitor.
In the degaussing device having approximately half the capacity, the switching switch
First, the first capacitor is connected to the degaussing coil.
And the charging current of the first capacitor is
To the second condenser.
Is connected to the degaussing coil and the second capacitor
Switching so that the charging current flows to the degaussing coil
Demagnetization method to be used.