| 摘要 |
PURPOSE:To detect a tilt angle with higher accuracy by summing up outputs of light receiving elements by an adding circuit and making the quantity of light emission of a light emitting element constant by a light quantity controller according to the sum output signal. CONSTITUTION:The adder circuit 17 which sums up the output signals of amplifier circuits 11 and 12, a light quantity control circuit 18 which ocntrols electric power supplied from a power source 16 according to the sum output signal, etc., are provided. Then when the case 1 of a tilt detection part slants by an angle theta1, the output signals of the light receiving elements 6 and 7 are processed 10, so that an output signal corresponding to the angle theta1 appears at a terminal 15. The tilt angle is detected from the level of the output signal and the tilt direction is detected from its polarity. Then, when the temperature of the element 2 varies and its light output varies, the output signal of the circuit 17 also varies. The circuit 18 controls a current or voltage supplied from the power source 16 to the element 2 according to the variation to hold the output of the element 2 at an invariably specific level. Consequently, the output variation of the element 2 is corrected and error components are removed from the output signal.
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