Passive infrared sensor and obstacle detection system used in the same

摘要

According to one embodiment of a passive infrared sensor, a passive infrared sensor 1 where an infrared sensing element 5 and an optical system 4 that sets a detection area A 1 of the infrared sensing element 5 are covered with a cover 2 . The passive infrared sensor 1 includes: a light emitting element 6 that emits infrared light from the inside of the cover 2 to the outside through the optical system 4 ; a reflective region 2 b that is disposed outside the cover 2 and reflects at least some of the infrared light emitted from the light emitting element 6 ; and a light receiving element 7 that receives the infrared light reflected by the reflective region 2 b, transmitted through the optical system 4 and reaching the inside of the cover 2.