Contactless touch input system
A proximity sensor, including light emitters and light detectors mounted on a circuit board, two stacked lenses, positioned above the emitters and the detectors, including an extruded cylindrical lens and a Fresnel lens array, wherein each emitter projects light through the two lenses along a common projection plane, wherein a reflective object located in the projection plane reflects light from one or more emitters to one or more detectors, and wherein each emitter-detector pair, when synchronously activated, generates a greatest detection signal at the activated detector when the reflective object is located at a specific 2D location in the projection plane corresponding to the emitter-detector pair, and a processor sequentially activating the emitters and synchronously co-activating one or more detectors, and identifying a location of the object in the projection plane, based on amounts of light detected by the detector of each synchronously activated emitter-detector pair.
1. A proximity sensor, comprising:
a circuit board;
a plurality of light emitters mounted on said circuit board;
a plurality of light detectors mounted on said circuit board;
two stacked lenses, positioned above said light emitters and said light detectors, comprising an extruded cylindrical lens and a Fresnel lens array, wherein each of said emitters, when activated, projects a light beam through said two stacked lenses along a common projection plane, wherein a reflective object located in the common projection plane above said two stacked lenses reflects light projected at the reflective object from one or more of said emitters to one or more of said detectors, and wherein each emitter-detector pair, comprising one of said emitters and one of said detectors, when synchronously activated, is expected to generate a greater detection signal at the activated detector, when the reflective object is located at a specific 2D location in the common projection plane corresponding to the emitter-detector pair, than when the reflective object is located at any other location in the common projection plane; and
a processor connected to said emitters and to said detectors, sequentially activating each of said emitters and synchronously co-activating one or more of said detectors, and identifying a location of the reflective object in the common projection plane, based on amounts of light detected by the detector of each synchronously activated emitter-detector pair, wherein said processor is configured (i) to generate a first vector, the components of which correspond to the emitters, the components comprising, for each emitter, a sum of values corresponding to amounts of light detected by the detector of each synchronously activated emitter-detector pair having that emitter, (ii) to generate a second vector, the components of which correspond to distances from the sensor, the components comprising a sum of values corresponding to amounts of light detected by the detector of each synchronously activated emitter-detector pair whose corresponding specific 2D location is the same distance from the sensor, and (iii) to calculate at least one member of the group consisting of movement, velocity, size and location of the reflective object, along a first dimension of the common projection plane, based on the first vector, and along a second dimension of the common projection plane, based on the second vector.
2. The proximity sensor of claim 1 , wherein at least one of said two stacked lenses is a collimating lens for the projected light beams.
3. The proximity sensor of claim 2 , wherein said Fresnel lens array is configured to collimate the projected light beams.
4. The proximity sensor of claim 1 , wherein said extruded cylindrical lens is positioned between said Fresnel lens array and said circuit board.
5. The proximity sensor of claim 1 , wherein said extruded cylindrical lens serves as a support structure for the sensor.
6. The proximity sensor of claim 1 , wherein said processor is further configured to identify gestures performed by the reflective object in the common projection plane, based on amounts of light detected by the detector of each synchronously activated emitter-detector pair.
7. The proximity sensor of claim 1 , wherein said processor is further configured to identify an edge shape of the reflective object by generating a pixel image having pixel values based on assigning values corresponding to the amount of light detected by each detector of a plurality of synchronously activated emitter-detector pairs to the specific 2D location corresponding to the emitter-detector pair, and correlating the generated pixel image with a reference edge shape.
8. The proximity sensor of claim 1 , wherein said processor is configured to identify gestures performed by the reflective object, by correlating a time series of pixel images, each pixel image comprising pixel values that are based on assigning values corresponding to the amount of light detected by the detector of each synchronously activated emitter-detector pair to the specific 2D location corresponding to the emitter-detector pair.
9. The proximity sensor of claim 1 , wherein said two stacked lenses fan out the light beams from said plurality of light emitters in non-parallel non-intersecting directions along the common projection plane.
10. The proximity sensor of claim 1 , encased in hermetically sealed plastic transparent to infrared light.