| 摘要 |
PURPOSE:To see a television only by a person paying a charge by attaching a switch terminal sliding with a pushing force at the time of attaching the earphone to an earphone speaker and turning on and off a power source by a sensor circuit operating according to the movement thereof. CONSTITUTION:The earphone 34 is delivered to a user in exchange for the looking charge of a television and inserted into the earphone speaker 31, and then, the switch terminal 32 is pushed out by the pushing force of the earphone 34 and an incident light from a light source 37 to a phototransistor 36 is inter rupted. A phototransistor 44, since light is not irradiated, is turned off, and since the base potential of a switching transistor 42 goes to a high level, it is turned on. Thereby, a power transistor 43 is conductive, a power is supplied to a circuit load 45 from a power source 41 and the user can see a liquid crystal television.
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