| 摘要 |
PURPOSE: To prevent power consumption and the rise in ambient temperature by controlling alternating currents flowing to a positive-temperature-coefficient resistance and a demagnetizing coil. CONSTITUTION: With a switch 31 ON, AC power is applied to a rectifying circuit 1 and converted into a direct current. This direct current is smoothed by a capacitor 33 and then an RC charging circuit 3 charges a voltage in a capacitor 7 through a resistance 6; and a transistor 8 stays ON and a relay 4 also stays ON unit the capacitor is charged up to a specific voltage. At the time of power supply, an alternating current flows to the demagnetizing coil 34 through the positive-temperature-coefficient resistance 35 of approximately 20Ωto erase the magnetic field of a monitor or television tube. Then the resistance value of the resistance 35 increases 1 to 2 seconds later and the current of the coil 34 is decreased. As the voltage of the capacitor 7 rises, the relay 4 is turned off associatively. Therefore, the coil 34 is released and the temperature of the resistance 35 falls and decreases in resistance value, so that the magnetic field can be erased only when the power is supplied to the coil 34. Thus, the power consumption is reduced and the ambient temperature is prevented from rising.
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