| 摘要 |
PURPOSE:To photograph securely even when a time from the entrance of a subject into a photographic field angle to the arrival at intended photographic position is extremely short by performing releasing operation on deciding that a subject whose temperature is different from ambient temperature exits from the field angle. CONSTITUTION:When the subject whose temperature is higher than the temperature in the visual field of a pyroelectric infrared sensor 5 enters the visual field, the temperature in the visual field of the sensor 5 varies from a low state to a high state and the sensor 5 outputs a positive signal. The signal is amplified by an amplifier and when it exceeds a specific value, a positive signal detecting circuit 9 outputs an H-level signal instead of an L-level signal, so that the output of a delay circuit 12 varies from tan L level to an H level. When the subject does not leave the visual field, a negative signal detecting circuit 10 does not output an H-level signal, so the output of the circuit is inverted from the H level to the L level after a delay time set in the delay circuit 12 is elapsed, so that a release circuit 13 operates.
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