Patent ID: 7274438

Claim:
A monitoring device that produces a light curtain for monitoring spatial areas ( 2 ), comprising: a combination of at least one emitter ( 3 ) for emitting radiation pulses into an area and at least one receiver ( 4 ) for receiving emitted radiation as reflected from an object within the area, the emitted radiation pulses forming a reflectorless light curtain, said at least one receiver having a semiconductor sensor ( 7 ) with a plurality of light-sensitive elements ( 6 ) with short-time integration for mapping a predefined spatial area ( 2 ) within the area into which the radiation pulses are emitted; wherein, the spatial area is defined by a predefined distance value range, said at least one emitter and said at least one receiver are located on a same side of the spatial area, the at least one receiver ( 4 ) is connected to an evaluation unit, the evaluation unit comprising a runtime determining unit ( 9 ) connected to said plurality of light-sensitive elements ( 6 ), said runtime determining unit ( 9 ) generates a distance image of the object based on a measuring runtime (T) of the radiation pulses emitted from the emitter ( 3 ) to the object and reflected back to the elements ( 6 ) of the sensor ( 7 ) and calculating a distance value of the object from the receiver ( 4 ), and determines whether the monitored object is one of i) in front of the spatial area ( 2 ) and ii) behind the spatial area ( 2 ) based on a comparison of the calculated distance value to the predefined distance value range, wherein said emitter and said receiver are reflectorless and the device is free of any reflectors.