Industrial robot having a sensor unit

An industrial robot comprising an arm, a driving source for driving said arm, an operation unit provided at a tip end of said arm, said operation unit comprising a nozzle unit which sprays paint in the form of paint mist and carries out a painting operation, a sensor unit provided at the tip of said arm, in a vicinity of said operation unit, and engaing means provided at the tip end of said arm,

• said sensor unit comprising a sensor of a non-contact type for detecting a workpiece which is to be subjected to an operation carried out by said operation unit, said workpiece having a door which is provided with a groove defined by a pair of window frames, a shutter plate which undergoes displacement between a first position opposing a front of said sensor and a second position deviated from said front of said sensor for preventing said paint mist from entering said front of said sensor when said shutter plate assumes said first position, means for causing said shutter plate to displace from said first position at least while said sensor carries out a detecting operation to detect said workpiece, and for causing said shutter to assume said first position at least while said operation unit carries out said operation, a case for accommodating at least said front of said sensor and said shutter plate, said case being provided with an air chamber and an opening which opposes said front of said sensor, said shutter plate in said first position being located between said front of said sensor and said opening, said air chamber communicating to said opening through a region which includes said front of said sensor and the vicinity thereof, and air purge means for ejecting air in said region, said air purge means comprising means for supplying air to said air chamber,
• said sensor detecting one of said window frames of said workpiece and the other of said window frames while said tip end of said air is forwardly driven, said tip end of said arm being backwardly driven by a predetermined distance in response to the detection of said two window frames so that said engaging means engages with said groove, said engaging means moving said door after engaging said groove.