| 摘要 |
PURPOSE:To change easily a detection gap length and to improve the detection sensitivity, by comparing and amplifying the back pressure of a detecting nozzle and a reference pressure by a differential pressure amplifier in a hydraulic type micrometer. CONSTITUTION:Compressed air from an air source 11 has pressure reduced by a reducing valve 12 and is adjusted to a supply pressure PS. A gauge 13 is used for this adjustment. When air of the supply pressure PS is jetted onto the surface of a material 17 to be measured on a reference face 16 from a detecting nozzle 15 through a fixed orifice 14, a backpressure P1 corresponding to a detecting gap lX is generated in the supply path to the nozzle. The back pressure is supplied to a comparison pressure supply port of a differential pressure amplifier 18. A reference pressure P3 adjusted by an orifice 19 and a needle valve 20 is supplied to a comparison pressure input port of the differential pressure amplifier, and a pressure switched 23 is operated when the gap length lX becomes a length corresponding to the reference pressure. |
