| 摘要 |
PROBLEM TO BE SOLVED: To provide method and apparatus for detecting the liquid level in a cassette optically. SOLUTION: The liquid level selector comprises four infrared LEDs 53-56 being set, respectively, in an optical baffle and an array of four phototransistor receivers 63-66 wherein the LEDs are arranged substantially vertically immediately on the outside of a cassette 1. The vertical arranging line of LEDs is substantially in parallel with the moving direction of liquid/air interface 40 in the cassette. The LED is directed upward by about 20 deg. from the horizon. In the substantially vertical arrays 53-56 of four corresponding phototransistor receivers, respective receivers 63-66 are set oppositely to the cassette on the outside thereof while directing the LEDs. |
