JPS5916486A - Degaussing circuit - Google Patents

Abstract

PURPOSE:To eliminate the power loss of a circuit at a non-degaussing state in a degaussing circuit, by providing a switch possible for automatic control to a degaussing circuit system and flowing a degaussing current as required only. CONSTITUTION:A power is applied from an AC power supply 1 to a main power supply section 5a in closing a power switch 7. A sub-power supply section 9 produces a voltage and a current required for the device of the degaussing circuit system from the main power supply section 5a. When the power from the sub-power supply section 9 is applied to the 1st control section 11 after the power switch 7 is closed, the starting is instructed to an oscillating section 12. Further, a counter secton 13 is reset for starting at the same time. A clock frequency generated from the oscillating section 12 is specified with the necessity of the operating speed of the degaussing circuit and depends on a posistor 2, and the degaussing is finished sufficiently in about 10sec.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a degaussing circuit, and is an improvement in which a degaussing coil is used to remove magnetization in a display device using a color CILT (cathode ray tube) monitor or a color television set. This is related to the iPt II river.

Conventional degaussing circuits of this type include those shown in FIGS. 1 and 2. FIGS. 1 and 2 are circuit configuration diagrams showing a manual degaussing circuit and an automatic degaussing circuit, respectively, in a conventional degaussing circuit (18 circuits).

In Figures 1 and 2, 1 is an alternating current (AC) power supply, 2
is a POSISTOR (positive characteristic thermistor), 3 is a POSISTOR similar to POSISTOR 2, but with an intermediate tap, 4 is a degaussing coil, 5 is a power supply circuit for the display device, 6 is a degaussing switch, 7
is a power supply switch 2, and 8 is a resistor.

Next, the operation of the conventional degaussing circuit shown in FIGS. 1 and 2 will be described. In Fig. 1, when the degaussing coil 6 is manually closed, the POSISTOR 2 and the degaussing coil 4 are closed.
The impedance of the degaussing circuit consisting of
Since the impedance of the AC power source 1 is sufficiently small compared to the impedance of
Current flows. - The resistance value of POSISTOR 2 changes depending on the temperature as shown in Figure 4, so the power loss caused by POSISTOR 2 becomes heat, and as a result, POSISTOR 2 rapidly loses its resistance value due to self-heating. increases to As a result, the impedance of the degaussing circuit increases and the degaussing current DC attenuates as shown in FIG. 5. Therefore, the relationship between the magnetic field H generated by the current flowing through the degaussing coil 4 and the magnetic flux density B is , B shown in FIG.
-H curve (magnetic saturation curve 9), and the magnetized object can be demagnetized.

Furthermore, FIG. 2 shows an automatic version of the manual degaussing circuit shown in FIG. 'Except for the period when the surge current flows to the power supply circuit 5, the degaussing current IDC to the degaussing circuit flows in the same manner as shown in FIG. 1 above. Here, ■ of POSISTOR 3
In the case of the manual degaussing circuit explained in Figure 1 above, the degaussing operation ends when the resistance between As an alternative to fixing 6 in the closed state, a resistor 8 is connected to the center tap of the posister 3.

The resistance value of this resistor 8 is determined by the resistance value of the resistor 3 whose resistance value is fixed in the state of
It is sufficiently smaller than the resistance value of coil 4, and the initial state (
Here, the resistance value is set to be smaller than the above resistance value so as not to affect the demagnetizing effect. Therefore, a weak current does not flow into the degaussing coil 4 when the resistance value of the POSISTOR 3 is saturated, and most of the current returns to the electric γb11 line through the ■-■ of the POSISTOR 3 and through the resistor 8. .

Therefore, a constant current always flows through the POSISTOR 3 while the 111:γ original switch 7 is closed, and balance is maintained at a level where the resistance value is large.

Conventional degaussing circuits are configured as described above, so if an automatic reset type switch is used in a manual degaussing circuit, the operator must hold the switch for a certain period of time, and the automatic If the switch is not a reset type, there is a problem in that the power consumption of the circuit increases if the switch is forgotten to be turned off. On the other hand, in the automatic degaussing circuit, when the above-mentioned hand η91 type switch is closed at the time, the power loss in the above-mentioned degaussing 1 "11 path is large.
If the demagnetization operation is insufficient when the power is turned on, or if you want to perform demagnetization during use, turn off the 4-source switch and leave it for about 3 minutes.The temperature of the POSISTOR will drop and it will be fully demagnetized. There was a drawback that one had to wait until the 4Lf resistance value t reached to achieve the demagnetizing effect. Furthermore, if the performance of the POSISTOR deteriorates due to changes over time, the leakage current that flows after degaussing will increase, causing the screen to oscillate. There were some drawbacks such as causing

The present invention has been made in order to eliminate the drawbacks of the conventional devices such as the one described above, and is a display device using a cathode ray tube.
In a degaussing circuit having a degaussing coil for removing bandage, the circuit that automatically performs the degaussing operation is closed in the source ON 114, and after a certain period of time has elapsed until the demagnetization is completed, It has a configuration that includes an automatically controllable switch that opens the circuit and a control circuit that controls the drive of this switch, eliminating power loss in the non-demagnetized state of the previous M self-deenergizing iF4 circuit and reducing leakage current. The object of the present invention is to provide a degaussing circuit that can prevent color tubes from being caused by the

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a circuit diagram showing a degaussing circuit according to an embodiment of the present invention. In Fig. 3, ■ is an AC power supply, 2 is a POSISTOR, 4 is a degaussing coil that generates a magnetic field for degaussing,
5a is a main power source for a color CRT monitor, color television, etc., and 71d is a power switch. Also, 9(A
A sub-power supply section that takes out power for the degaussing circuit system from the main power supply section 5a; 1o is a switch section that conducts and disconnects the degaussing current 'DG flowing through the degaussing circuit; 11 is a command for making the switch section 1o into a predetermined state 51iμ; , the first open side 1 for decoding
12 is an excavation section that generates a clock signal or converts it into a predetermined difference width as a clock signal by providing a vertical synchronization pulse from a display circuit (not shown); 13 is a section that generates a clock signal from the excavation section 12; a counting section that counts the clock signal of and sends a command to the first control section 11; 14 is a second open side section that drives the switch section 1o by a signal from the first control section 11; 15 is an automatic return type switch for manual degaussing.

Next, the operation of the degaussing circuit shown in FIG. 3, which is an embodiment of the present invention, will be explained. When the power switch 7 is closed, power is supplied from the AC power supply 1 to the main power supply section 5a. The auxiliary power source section 9 generates the voltage and current necessary for the degaussing circuit and road system equipment from the main power source section 5a. After the power switch 7 is closed, the power from the auxiliary power source section 9 is supplied to the first control section. 11
When supplied, it instructs the excavation unit 12 to start up. At the same time, the counter section 13 is reset and activated.

The clock frequency generated by the excavation section 12 is determined by the necessity of operating speed of this degaussing circuit, and also depends on the POSISTOR 2, or degaussing is sufficiently completed in about 10 seconds. In the past, it is better to use an excavation circuit using a crystal excavation element etc. for the excavation section 12, for example, a vertical synchronization frequency with a color CRT monitor and a color television/S, or 401-1z to 801 (z). Considering this, if the above oscillator circuit is used, the number of parts of the circuit can be reduced and the cost can be reduced.With such a circuit configuration, the clock signal generated from the excavation part 12 is
400 to 800 clocks per 10 seconds is enough, and accordingly, the circuit configuration of the counter section 13 can be easily made. At the same time that the counter section 13 starts counting up or counting down, the first control section 11 controls the degaussing current
A signal is given to the second control section 14 of the switch section 10 in order to close the switch section 10 for flowing Do to the POSISTOR 2 and the B coil 4. Close the switch section 1.
The element used for 0 may be a contact element such as a relay, or may be a semiconductor switch.

Next, when the counter unit 13 completes a predetermined count-up or count-down, it transmits an end signal to the first control unit 11. Upon receiving the termination signal, the first control section 11 instructs the second control section 14 to control the switch section 1.
0 is commanded to open, and the second control section 14 opens the switch section 10. At the same time, the first control unit 11
is the oscillating unit 12. It notifies the counter section 13 that the operations related to degaussing are completed, and stops these operations.

In the degaussing circuit described above, the degaussing operation is performed immediately at the same time as the power is turned on, and when the degaussing is completed after a certain period of time, the degaussing current ``DC distribution path'' is cut off. Since no current flows at all, there is no power loss in the circuit in the non-demagnetized state, and the screen is no longer affected by leakage current.

- In the degaussing circuit described above, if you want to manually degauss, press the switch 15 and the first control unit 111 detects the makoia and demagnetizes as in the case of automatic degaussing described above.・Create Touka. Therefore, switch 1
5, by using the self-IIF [policewoman's switch], the operator (just press the switch 15, which simplifies the operation). In the above embodiment, the case where the sub-power supply unit 9 is used is explained. However, when there is no need to separate the 21st and 2nd sides of the source, for example for color R'r monitors and color televisions, the fly/gear transformer 3
Since the power is generated from the next winding, you may use this power supply. When it is necessary to separate the primary and secondary sides of the power supply, an optical isolator or the like is used in the second control section 14.

It can also be separated.

Furthermore, in the above embodiment, the degaussing current is supplied directly from a commercial power line such as the AC power supply 1, but AC power is generated from a side separated from the primary side by the main power supply section 5a, and from this A demagnetizing current may be applied.

As described above, according to the degaussing circuit according to the present invention, the degaussing circuit system includes a switch that can be controlled together and a control circuit that controls the drive of this switch; Since the degaussing iH current is configured to flow through the circuit, it has the special feature of eliminating the power loss of the degaussing circuit in the non-degaussing state and preventing the influence of leakage current. In addition, when manual degaussing is performed, there is a risk of insufficient degaussing due to inadvertent interruption of manual degaussing, increased power loss due to forgetting to cancel the degaussing, or risk of burnout of circuit components. It has the excellent effect of being able to remove all of the particles.

[Brief explanation of the drawing]

1 and 2 are circuit configuration diagrams showing a manual degaussing circuit and an automatic degaussing circuit, respectively, in a conventional degaussing circuit, and FIG. 3 is a circuit configuration showing a degaussing circuit that is an embodiment of the present invention. 4 is a temperature-strength value characteristic diagram of the POSISTOR, FIG. 5 is a waveform diagram showing changes in the degaussing current, and FIG. 6 is an explanatory diagram showing the relationship between the degaussing current and the B-H curve. 1... AC illumination, 2, 3... Posister, 4... 4 degaussing coil, 5...' power supply circuit, 5a...・Main power supply section, 6...
Degaussing switch, 7...Electric 7 original switch,
8. . ...Resistance, 9... Sub-power supply section, 10...
・Switch unit, 11...First control unit,
12......Oscillating section, 13...-...
Counter section, 14...Second control section, 15...
······switch. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In a display device using a cathode ray tube, in a degaussing circuit having a degaussing coil for removing magnetization, the circuit that automatically performs degaussing operation is closed when the power is turned on, and after a certain period of time has elapsed until the demagnetization is completed. . A degaussing circuit comprising: an automatically controllable switch that opens the circuit; and a control circuit that controls driving of the switch.