| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical encoder, wherein the duration, in which an overcurrent continuously flows through an output transistor is short, even when a load short circuit arises due to malfunction of load, such as of a pulse counter, when a scale plate of the optical encoder is quickly driven, and wherein the output transistor will not be broken. SOLUTION: The output circuit of the optical encoder is provided with a diode, passing only current in the charging direction, in series with a charge resistor, and a discharge resistor, provided in parallel with a capacitor. Thus, the discharge speed of the capacitor charged by the overcurrent is lowered; the capacitor is not fully discharged, during the pulse signal off duration; and the electric charge is left In addition, when the capacitor is charged and when the terminal voltage of the capacitor reaches VBE of a protective transistor, the protective transistor is turned on. As a result, the output transistor is turned off. COPYRIGHT: (C)2005,JPO&NCIPI
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