Optical proximity sensor
A sensor including lenses, light emitters, each emitter projecting light out of a lens in a particular emission direction along a detection plane, light detectors, each detector detecting maximum light intensity when light enters a lens at a particular detection angle, a table of hotspots, each hotspot corresponding to an emitter-detector pair, the hotspot being a two-dimensional location in the detection plane along the emission direction of the emitter of the pair where projected light reflected by an object placed at that location, enters the lens for the detector of the pair at the detection angle of the detector, and a processor receiving outputs from the detectors corresponding to detected amounts of projected light reflected by an object in the detection plane, and calculating a two-dimensional location of the object in the detection plane based on the received outputs and based on hotspots for synchronously activated emitter-detector pairs.
1. A proximity sensor comprising:
a housing;
a plurality of lenses mounted in said housing;
a plurality of light emitters mounted in said housing, each light emitter being positioned in relation to a respective one of said lenses so as to project light out of the lens in a particular emission direction along a detection plane;
a plurality of light detectors mounted in said housing, each light detector being positioned in relation to a respective one of said lenses so as to detect maximum light intensity when light enters the lens at a particular detection angle;
an activating unit mounted in said housing, synchronously activating emitter-detector pairs;
a non-volatile computer-readable storage medium storing a table of hotspots, each hotspot in the table corresponding to an emitter-detector pair, the hotspot being a two-dimensional location in the detection plane along the emission direction of the emitter of the pair where projected light reflected by an object that is placed at that location, enters the lens for the detector of the pair at the detection angle of the detector; and
a processor receiving outputs from said detectors corresponding to detected amounts of projected light reflected by an object in the detection plane, and calculating a two-dimensional location of the object in the detection plane based on the received outputs and based on corresponding hotspots for the emitter-detector pairs synchronously activated by said activating unit.
2. The proximity sensor of claim 1 , wherein different light detectors are positioned in relation to their respective lenses such that their detection angles are different.
3. The proximity sensor of claim 1 , wherein different light emitters are positioned in relation to their respective lenses such that their emission directions are different.
4. The proximity sensor of claim 1 , wherein said processor interpolates the hotspots corresponding to those of the emitter-detector pairs synchronously activated by said activating unit for which the processor's received outputs are maximum or nearly maximum vis-à-vis all of the received outputs.
5. The proximity sensor of claim 4 wherein said processor interpolates the hotspots using linear weights proportional to the outputs received by said processor from the corresponding emitter-detector pairs.
6. A method for calculating a location of a proximal object, comprising:
providing a housing in which a plurality of lenses is mounted;
providing a plurality of light emitters in said housing, each light emitter E being positioned in relation to a respective lens L such that light emitter E projects a light beam in a particular emission direction φ E along a detection plane P;
providing a plurality of light detectors in said housing, each light detector D being positioned in relation to a respective lens L such that light entering lens L is significantly detected at light detector D when the light enters lens L at a detection angle θD;
providing a non-volatile computer-readable storage medium storing a table of hotspots, each hotspot H(E, D| O) being a two-dimensional location in detection plane P corresponding to an emitter-detector pair (E, D) and to the shape of an object O, the hotspot H(E, D| O) being a location along the light projected from emitter E of the pair along direction φ E , where projected light reflected by the object O, when placed at that location, enters the lens L for detector D of the pair at detection angle θD;
synchronously activating emitter-detector pairs (E, D);
measuring detection by light detector D of each synchronously activated pair (E, D) of the light projected by light emitter E of the pair that is reflected by object O into the lens of light detector D; and
calculating a two-dimensional location of object O in detection plane P based on the measured detections, and based on the corresponding hotspots H(E, D| O) for the emitter-detector pairs (E, D) activated by said synchronously activating.
7. The method of claim 6 , wherein different light emitters E are positioned in relation to their respective lenses such that their emission directions φ E are different.
8. The method of claim 6 , wherein different light detectors D are positioned in relation to their respective lenses such that their detection angles θ D are different.
9. The method of claim 6 , further comprising interpolating the hotspots H(E, D| O) corresponding to those of the emitter-detector pairs (E, D) synchronously activated by said synchronously activating for which the measured detections are maximum or nearly maximum vis-à-vis all of the measured detections.
10. The method of claim 9 further comprising interpolating the hotspots H(E, D| O) using linear weights proportional to the measured detections from the corresponding emitter-detector pairs (E, D).