Proximity sensor
First Claim
1. A proximity sensor comprising an illumination means for illuminating a scene with an array of spots of light, a detector arranged to receive light reflected from the scene and a mask, located in the optical path of light from the scene to the detector, the mask having transmissive portions and non-transmissive portions and being arranged, together with the illumination means and detector such that, in use, light reflected from a target from within a first range of distances from the sensor is transmitted through the mask to the detector and light from a second range of distances is not transmitted through the mask.
3 Assignments
0 Petitions
Accused Products
Abstract
This invention relates to a proximity sensor. An illumination means (2) projects an array of spots (40) towards a scene. Detector (8) looks towards the scene through a mask (6). The mask (6) is arranged such that light from a target at a certain range, for instance far object (14) is not transmitted to the detector. Light reflected from a close object (16) however passes through the mask (6) and is incident on the detector (8). A rise in the intensity of incident light at the detector (8) is determined by threshold detector (10) and used to operate an alarm (12).
35 Citations
15 Claims
- 1. A proximity sensor comprising an illumination means for illuminating a scene with an array of spots of light, a detector arranged to receive light reflected from the scene and a mask, located in the optical path of light from the scene to the detector, the mask having transmissive portions and non-transmissive portions and being arranged, together with the illumination means and detector such that, in use, light reflected from a target from within a first range of distances from the sensor is transmitted through the mask to the detector and light from a second range of distances is not transmitted through the mask.
Specification