| 摘要 |
PURPOSE:To easily constitute a sensor system which includes a connection cable and to improve assembling performance by setting an optional gap where a body to be detected can pass and sending fed-back light to a photodetection body while there is an afterglow left on a fluorescent screen. CONSTITUTION:An optical cable 1 and the fluorescent surface 8 are fixed while the optical axes are so adjusted that light is passed and received most efficiently. The fluorescent surface 8 is made of a phosphor body with large afterflow effect and has an afterflow with light emitted by the optical fiber 1 to generate emitted luminous flux phiR of the phosphor, and the afterglow remains even after the signal T falls to Low. A level holding level decision circuit is further equipped with a level detecting circuit and a reference level VTH is compared with the level of a photocurrent V0 obtained by amplifying and converting a photocurrent IL, thereby deciding that a shutter 9 is not at a detection place when the signal V0 is higher than the level VTH. When the shutter 9 is present between the optical cable 1 and fluorescent surface 8, light emitted by the fluorescent surface 8 and the signal amplified and converted by the light power source of a photodetecting element have waveforms shown by phiR, IC, and VOL respectively, thereby detecting the presence of the shutter 9.
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