| 摘要 |
PURPOSE:To prolong the useful life of a photocoupler sensor, by providing a controlling transistor and passing an electric current to the photocoupler sensor only at the time of a printing operation which requires mark detection. CONSTITUTION:Even when a power source is turned ON, a controlling transistor 6 is not turned ON if a control signal is not sent to the transistor 6 through a control signal input line 7, and no power source current is passed to a photocoupler sensor 2. When the control signal is sent to the controlling transistor 6 to turn ON the transistor 6 before the start of a printing operation under the operation of a printer according to a sequence, a current is passed to a light-emitting diode 2a of the photocoupler sensor 2 through a power source line 1, and the diode 2a emits light, so that a light-receiving transistor 2b is turned ON, and mark detection is performed. Each time printing on one sheet is completed, the control signal is cut off, and the power source current supplied to the photocoupler sensor 2 is also cut off. |
