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Unformatted text preview: otted disc or a linear scale is sensed. In this way, it is possible to
achieve a digital potentiometer without sliding contact. Relatively high switching
frequencies are possible, for example up to 1 MHz. Also light barrier sensors are
available, which can detect the direction of movement of an object. © Festo Didactic GmbH & Co. KG • FP 1110 241 15. Special designs and variants of proximity sensors 15.2.2 Frame barrier sensors
Frame barrier sensors operate according to the principle of a light curtain. On two
opposite sides of the frame a large number of emitters and receivers are fitted in
close alignment, completely covering the inside of the frame with a light curtain. Fig. 15.2.2: Frame light barrier Frame sensors are used preferably to detect small parts falling through the frame,
for example for ejection monitoring of punched or pressed parts. Because of their
application in dynamic processes, frame sensors generally only have a dynamic
switching behaviour. Permanently existing parts, such as a transparent conveyor
tube which may be contaminated by dust and oil are therefore not detected. The
response time of frame sensors, for...
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This note was uploaded on 11/01/2012 for the course CHEMICAL 102 taught by Professor Jamesrodriguez during the Spring '12 term at Universidad Politécnica de Cartagena.
- Spring '12