| 摘要 |
PURPOSE:To prevent a television receiver from failing by providing the television receiver with a power supply circuit that functions that unless a certain period of time passes after one of power supply units for the television receiver acts, the other power supply unit does not act. CONSTITUTION:In the first power supply unit 3, when an AC input is applied to a plug 1, a control circuit 4 acts, a voltage is generated at the secondary side of transformer 8, and a DC voltage is applied to a load 12. The second power supply unit 13 acts in the same way as the first power supply unit 3. Unless the second power supply unit acts, no current flows in a diode 26 of optoisolator 25 and a control circuit 4 is not oscillated, so output from the first power supply unit 3 is zero. When the second power supply unit 13 acts, a control circuit 14 acts, an output voltage is generated, and a delay circuit 29 acts. After a certain period of time passes, a voltage is supplied to a resistor 28, a current flows in the diode 26, and the control circuit acts to oscillate. In this constitution, a voltage is applied to the load 12, while a voltage is not applied to a load 22, thereby causing the television receiver not to fail. |
