| 摘要 |
PURPOSE:To perform secure operation to a weak ultraviolet ray and speedy detection to an intense ultraviolet ray by using a retriggerable one-shot multivibrator and setting its monostable period properly. CONSTITUTION:Output pulses from a discharge tube 1 are integrated by a counter circuit 4 and when the output of the counter 4 reaches a value selected with a counter circuit selection switch 5, a detection output is generated through an output circuit 6. Output pulses from the discharge tube 1 which are generated by discrete discrete discharging are long in interval and the pulse width of the retriggerable one-shot multivibrator 3 is set shorter than it, so that the counter circuit 4 is reset and does not integrate the pulses. Then, when intervals of output pulses from the discharge tube 1 corresponding to the weak ultraviolet ray are shorter than the pulse width of the multivibrator 3, the counter 4 is not reset and performs secure integration to operate the output circuit 6. |
