| 摘要 |
1,270,128. Acoustic position-sensor. PITNEY BOWES Inc. 14 April, 1969 [22 April, 1968], No. 19046/69. Heading H4D. [Also in Division, G1, G4 and G5] For sensing if a surface is at a predetermined position, a pattern of acoustical interference fringes indicative of the prevailing position of the surface is established and an acousticallysensitive receiver comprising a fluidic amplifier is positioned so as to be coincident with one of the fringes existent when the surface is at the predetermined position. In the Fig. 12 embodiment for checking the thickness or continuity of a coating 157 on sheet base material 154 being moved over guide 150, a fluidic device 30 acting as a whistle (see Division G5) is in communication with conical cavity 174 in block 166 and generates ultrasonic waves which are reflected from coating 157. The incident and reflected waves interfere to give a fringe pattern 15a, 15b, 15c, 15d. If the coating surface is at a predetermined position 158, fringe 15d (a pressure null) intersects a receiver comprising a two-stage fluidic device 31 (see Division G4) communicating with conical cavity 183 and acting as a switch. This switch then gives a low pressure output, but if the coating thickness changes the fringe is displaced (e.g. to 15d<SP>1</SP> or 15d<SP>11</SP>) and the switch gives a high pressure output. |
