| 摘要 |
PURPOSE:To obtain a measuring instrument which is usable even in environment where various liquids are scattered by discharging a liquid which is admitted into a housing through a slide part from the housing forcibly through two through holes and an intake and outlet device for gas. CONSTITUTION:A reader 3 for a scale plate 2 on which graduations are provided linearly is provided in a sealed housing 1 across the scale plate 2. The housing 1 has the 1st through hole 8 and the 2nd through hole 9, and air is supplied from an air pressure source 10 to the through hole 9 through a filter 11 and a flow metering valve 12. The supplied air is discharged from the 1st through hole 8 after being passed in the housing 1. Therefore, even if moisture enters the housing 1 while stuck on the surface of a plunger 6, it is discharged together with the air which flows inside, so internal dew condensation is prevented and evil influence upon an electric system and others is evaded. |
