Robert Boschgmbh

Jean-Pierre Lavanchy

Dieter Handtmann

Frieder Heizmann

A workpiece is passed through a beam of either continuous or pulsed light which is interrupted thereby. The light impinges on a phototransducer such as a phototransistor, which is connected to an evaluation circuit. The evaluation circuit evaluates instantaneous light values with respect to movement of the workpieces in the beam, that is, evaluates variations derived from the transducer which preferably are decoded with respect to threshold levels and the time between sequential level exceeding, or passing, the thresholds is sensed, for example by a counter, to provide an output representative of the occurrence of changes in the light values indicative, for example, of discontinuities in the workpiece.

Apparatus and method to test workpieces for size, relative position,

An instrument for giving electrical indications of the distance between two reference points includes a light source, a primary light-sensitive detector and a secondary light-sensitive control detector. Both detectors may be photodiodes. In one embodiment, the light from the source is reflected from a reference plane and is intercepted by the primary detector and by the secondary control detector. The secondary control detector is part of a control loop which adjusts the intensity of the light source in such a manner that the photo current through the secondary control detector remains constant, thus providing compensation for changes in brightness and sensitivity due to aging, soiling and other influences.

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Neuchatel, Switzerland

Jean-Pierre Lavanchy