Abstract: A slot detecting apparatus comprises a sensor for detecting a slot of a workpiece, comparators, and a discriminating circuit. The sensor moves over the workpiece so as to traverse the slot and produce an output having a waveform which is substantially an M-shape. The comparators compare the level of the output of the sensor with a plurality of threshold levels which are mutually different, and each produce a comparison result for each of the plurality of threshold levels. The discriminating circuit discriminates the position of the slot based on a comparison result which indicates that the output of the sensor has a waveform which is substantially an M-shape, from among a plurality of comparison results which are obtained from the comparators for the plurality of threshold levels.

Abstract: An industrial robot comprises an arm, a driving source for driving the arm, an operation unit provided at a tip end of the arm, and a sensor unit provided at the tip end of the arm, in a vicinity of the operation unit. The sensor unit comprises a sensor for detecting a workpiece which is to be subjected to an operation carried out by the operation unit, a shutter for opening and closing a front of the sensor, and a mechanism for causing the shutter to open the front of the sensor at least while the sensor carries out a detecting operation to detect the workpiece, and for causing the shutter to close the front of the sensor at least while the operation unit carries out the operation.