| 摘要 |
1508085 Liquid level detector HECTRONIC AG 20 July 1976 [21 July 1975] 30073/76 Heading G1A A liquid level detector comprises a hollow body 10 of translucent or transparent material having a widened upper part 11 joined to a closed and narrow part 12 by a shoulder 13, a light source 16 arranged in the body so that light passes out through the walls of the narrow part 12 and, in the absence of liquid outside the detector, through the shoulder 13 to reach detector 19. In the presence of liquid, light is refracted away as shown by the dotted lines and does not reach the detector. The path from shoulder 13 to the detector is constructed so that light from directions other than those from the source does not reach the detector. As shown, light from the source 16 is collimated by a lens at the end thereof and strikes conical mirror face 26a. After passing through wall 12c and shoulder 13, the light is directed to the detector by reflecting surface 11b. Opaque block 118 both supports the source and prevents light therefrom reaching the detector directly. The detector may be movable along the axis of widened part 11 to adjust the detector for maximum sensitivity. In alternative embodiments different elements, comprising internal reflecting surfaces and opaque sections to reduce the angles of acceptance may be used between shoulder 13 and detector 19 to reduce the response to scattered or extraneous light. In another embodiment, the source is located at the closed end 12b of the narrow part 12 and the walls 12c of part 12 are inwardly convex to direct the light out of the tube. The detector is annular in this embodiment and preceded by an annular tapering passage between opaque elements replacing elements 111 and 118.
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