DEVICE FOR MEASURING TEMPERATURE AND DETECTING PHASE USED IN INFRARED RAY THERMOMETER

摘要

PURPOSE:To detect the phase and to perform synchronous commutation accurately even though noises are included in the output voltage of an amplifier, by providing two voltage comparators and providing hysteresis characteristics in at least one comparator. CONSTITUTION:An AC voltage signal is obtained in the amplifier 13 having a suitable filter characteristics from a sensor output voltage signal 12. The output voltage of the first comparator 14 is unstable in the case the output voltage of the amplifier is small. The synchronous commutation includes noises and becomes the cause of the error. Then the hysteresis characteristic is given to the second comparator 15 so that an intermittent signal is not generated until the output voltage of the amplifier 13 exceeds a present value. Therefore the logical sum is takne from an AND logical element 16, and the output voltage which includes the noise and the output voltage which does not include the noise can be distinguished from each other.