| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized liquid level detector which can detect a developing solution regardless of the kind of the solution even when the solution dries up by optically detecting prescribed upper and lower limit positions of the solution in a tank by means of a pair of sensors as sections to be detected and, at the same time, wiping off the solution adhering to the sections to be detected with a wiper. SOLUTION: The upper- and lower-limit sensors 11 and 12 of a liquid level detector 10 are composed of transmission type photosensors and provided with light emitting sections 11a and 12a and light receiving sections 11b and 12b. The sensors 11 and 12 are provided on a vertical line at prescribed upper and lower limit positions A and B of the surface level of a developing solution in a tank. The sensors 11 and 12 receive the light emitted from the light emitting sections 11a and 12a by means of the light receiving sections 11b and 12b and output electrical outputs. An elastic wiping material 14a which is brought into frictional contact with a transparent plate 13 are fixed to both end sections of a wiper 14 which wipes off the developing solution. When the sensors 11 and 12 of the detector 10 sink under the developing solution, the outputs of the sensors 11 and 12 become high levels, because the light is interrupted by the developing solution. When the sensors 11 and 12 come out of the solution, the outputs becomes low-level pulse-like outputs, because the light is intermittently intercepted by the wiper. |
