| 摘要 |
PURPOSE:To enable lighting a light emitting diode having lighting voltage of 2V in a display device using a battery having output voltage of 1.3V by charging a capacitor at the time of an ON state of a semiconductor element, discharging the electric charges at the time of an OFF state of a semiconductor switch, and adding it to the voltage of the battery in series. CONSTITUTION:A pulse generating circuit 4 generates a pulse signal having the prescribed duty ratio of, for example, 100Hz, and this pulse signal is applied to a base of a transistor 6 operating as a semiconductor switch from an output terminal 4D. When this pulse signal is applied to the base and the transistor 6 is turned on, since a collector 12 is made to a low potential being close to a potential of a ground line G, a capacitor 7 is charged by a current made to flow in through a diode 9. Consequently, voltage between a connecting point 13 and the ground line G is equal to the sum of voltage between both terminals of the capacitor 7 (voltage between the connecting point 13 and the collector 12) and voltage of a battery 2. And this summed voltage is applied to a light emitting diode 10.
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