| 摘要 |
PURPOSE:To eliminate possibility of erroneous operation caused by vibration by stopping temporarily the operation of a position detection means while vibration detection output exceeds a reference value, the vibration detection being provided in the vicinity of a radiation detection means. CONSTITUTION:In the vicinity of a radiation detection element 2 and preamplifiers groups 3 and 4, a vibration detection element and amplifier 21 such as a piezoelectric type vibratory sensor, are provided. The output therefrom is sent to a discriminator and one-shot circuit 23 to be compared to a reference voltage level L. The output of the vibration detection element and amplifier 21 exceeds the reference voltage level L when vibration is generated, and thereby pulse signal from the circuit 23 is generated. This pulse signal is sent to an AND gate circuit 7 via an inverting circuit 24 and therefore the outputs of an OR circuit and coincidence detection circuit 6 are blocked to be transmitted to a timing circuit 8 via the circuit 7, while the pulse signal is generated.
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