Patent ID: 7895791

Claim:
A passage barrier ( 10 ) comprising: partition walls ( 14 , 16 , 18 ) defining a passageway ( 12 ) therebetween; at least one barrier element ( 34 ) for optionally opening or blocking the passageway ( 12 ), wherein the barrier element can be swivelled about a swivelling axis through a swivelling area ( 38 ) of the passageway ( 12 ); at least one sensor system that detects the presence of a person in the swivelling area, the sensor system comprising: at least one sending unit ( 40 ) emitting detection waves, the sending unit ( 40 ) being arranged within one of the partition walls; at least one reception unit ( 42 ) providing output signals in response to at least one of said detection waves, the reception unit ( 42 ) being arranged within another one of the partition walls opposite to said one of the partition walls; and an evaluation unit for evaluating the output signals of the reception unit; wherein the sending unit ( 40 ) and the reception unit ( 42 ) are located such that said at least one of the detection waves extends from the sending unit ( 40 ) through the swiveling area to the reception unit ( 42 ), and wherein the at least one barrier element ( 34 ) is at least partially made of a material transparent to said detection waves such that the at least one of the detection waves extending through the swivelling area ( 38 ) passes through the at least one barrier element ( 34 ) without disrupting or substantially changing a direction of the at least one of the detection waves.