Light beam detection utilizing hologram

• US 5,220,409 A
• Filed: 12/18/1991
• Issued: 06/15/1993
• Est. Priority Date: 12/19/1988
• Status: Expired due to Term

• Current Assignee: AMP Limited
• Original Assignee: AMP Limited
• Inventors: Bures, Milan
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US07/814,301
• Time in Patent Office: 545 Days
• Field of Search: 356/375, 250/221, 340/709
• US Class Current: 356/621
• CPC Class Codes: G01V 8/22 using reflectors
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

Light beam detection is taught in method and apparatus where a light source of coherent light is directed toward a reflecting hologram made to simulate a parabolic mirror to generate light beams detected by photoreceptors along one side of an opto-frame, such receptors being scanned in a manner to preclude false detection of an object within the field of light. An an alternative, multiple light sources are used with a single receptor and an appropriate hologram.

Claims

1. In a system for detecting the penetration of a given area by an object and location thereof, first means operable to generate a sheet of light including a source of coherent light and lensing to spread said light over at least a substantial part of said area, at least one array of detectors arranged along at least one side of said area adjacent said source of light and a holographic reflecting means comprised of thin film reflecting holograms positioned along a side opposite to said source of light to reflect light from said source, said holographic reflecting means adapted to reflect said light along parallel lines extending over said area and a scansion means for selectively energizing said detectors in a sequence extending from a said detector closest to the said source of light to a said detector farthest from said source of light whereby to scan said area sequentially and preclude false detection of an object within said area.

2. Touch input apparatus having a touch screen for detecting the presence of an object within a given area defined by a plurality of sides, the apparatus including source means of coherent light adapted and positioned to broadcast light to strike at least one side, holographic means comprised of a flat planar film extending along the periphery of said area along each said at least one side, said film being developed to receive said light in a first beam pattern and reorient said light into at least a second beam pattern, detector means positioned along a further side to detect said light reoriented by said holographic means and responsive to said detection of light to generate a signal indicative of the absence of an object blocking a said beam within said area and further including means to detect the blocking of a said beam as an indication of the presence of an object within said area,

said source means comprising a first light positioned along a first said side and associated with X coordinates of said touch screen and a second light source positioned along a second said side and associated with Y coordinates, both arranged to emit light directly across said given area, said holographic means includes a pair of reflective film elements positioned on opposing third and fourth said sides to provide reflections representative of X and Y coordinates and said detector means includes elements positioned along said first and second sides to detect reflections traversing said given area from said holographic elements representative of said X and Y coordinates, and the apparatus further includes means to preclude the detection of false shadows caused by interruption of outgoing light from said light source means.

3. Touch input apparatus having a touch screen for detecting the presence of an object within a given area defined by a plurality of sides, the apparatus including source means of coherent light adapted and positioned to broadcast light to strike at least one side, holographic means comprised of a flat planar film extending along the periphery of said area along each said at least one side, said film being developed to receive said light in a first beam pattern and reorient said light into at least a second beam pattern, detector means positioned adjacent said given area to detect said light reoriented by said holographic means and responsive to said detection of light to generate a signal indicative of the absence of an object blocking a said beam within said area and further including means to detect the blocking of a said beam as an indication of the presence of an object within said area,

said light source means being constituted by a plurality of light sources oriented along a first said side to produce parallel beams essentially directly transversing said given area and covering said holographic means opposed therefrom, with said holographic means focusing said beams across said given region to a single point adjacent said given area and spaced from said holographic means to be detected by said detector means, and the apparatus further includes means to sequentially operate said light sources to produce a series of light beams detected by said detector means.

4. The touch input apparatus of claim 3 wherein said holographic means is a said film having a holographic recording thereon having characteristics to operate in the reflective mode.

5. The touch input apparatus of claim 4 wherein said detector means is a charge coupled device.

6. The touch input apparatus of claim 5 wherein said detector means is disposed along said first side.

7. Touch input apparatus having a touch screen for detecting the presence of an object within a given area defined by a plurality of sides, the apparatus including source means of coherent light adapted and positioned to broadcast light to strike at least one side, holographic means comprised of a flat planar film extending along the periphery of said area along each said at least one side, said film being developed to receive said light in a first beam pattern and reorient said light into at least a second beam pattern, detector means positioned along a further side to detect said light reoriented by said holographic means and responsive to said detection of light to generate a signal indicative of the absence of an object blocking a said beam within said area and further including means to detect the blocking of a said beam as an indication of the presence of an object within said area;

said detector means being constituted by a plurality of discrete receptor devices along a said side opposed from a said holographic means;

said holographic means being a said film having a holographic recording thereon having characteristics to operate in the reflective mode, and said light source means and said discrete receptor devices being arrayed along a common said side and operable to emit light directly across said given area and receive light directly transversing said given area respectively; and

the apparatus further including circuit means to selectively energize said discrete receptor devices in a sequential manner in a given direction to preclude the detection of false shadows.

8. The touch input apparatus of claim 7 wherein said light source means in a single source lensed to emit light to strike said holographic means in a first beam pattern and be reflected therefrom developing simultaneous reflection of light in said second beam pattern from said holographic means.

9. Touch input apparatus having a touch screen for detecting the presence of an object within a given area defined by a plurality of sides, the apparatus including source means of coherent light adapted and positioned to broadcast light to strike at least one side, holographic means comprised of a flat planar film extending along the periphery of said area along each said at least one side, said film being developed to receive said light in a first beam pattern and reorient said light into at least a second beam pattern, detector means positioned adjacent said given area to detect said light reoriented by said holographic means and responsive to said detection of light to generate a signal indicative of the absence of an object blocking a said beam within said area and further including means to detect the blocking of a said beam as an indication of the presence of an object within said area;

said light source means being a single source lensed to emit light to strike a first said holographic means in a first beam pattern;

said first holographic means being adapted to reorient said light into a said second beam pattern of parallel beams;

said apparatus including a second holographic means opposed from said first holographic means and being a film developed to receive said light in said second beam pattern and reorient said light into a third beam pattern;

said first and second holographic means are films having a holographic recording thereon having characteristics to operate in the reflective mode, and said light source and said detector means are disposed along a common side different from sides containing said first and second holographic means; and

said detector means being a charge coupled device disposed to detect said light reoriented by said second holographic means.

10. Touch input apparatus having a touch screen for detecting the presence of an object within a given area defined by a plurality of sides, the apparatus including source means of coherent light adapted and positioned to broadcast light to strike at least one side, holographic means comprised of a flat planar film extending along the periphery of said area along each said at least one side, said film being developed to receive said light in a first beam pattern and reorient said light into at least a second beam pattern, detector means positioned adjacent said given area to detect said light reoriented by said holographic means and responsive to said detection of light to generate a signal indicative of the absence of an object blocking a said beam within said area and further including means to detect the blocking of a said beam as an indication of the presence of an object within said area;

said holographic means including four distinct film elements associated in opposing pairs representative of X and Y coordinates and positioned and oriented to provide parallel beams of light transversing said area representative of said X and Y coordinates;

said coherent light source means comprising a single light source unit and including lensing to collimate said coherent light to strike a first said film element of said pair and be reflected thereby across said area to strike a second said film element of each said pair and be further reflected thereby to a respective detector means;

said apparatus further including a light splitter positioned between said lensing and said first film elements to cause said coherent light after collimating to be directed towards both said first film elements; and

each said detector means comprising a single charge coupled device associated with said pair operable to sense beams of light distinctly each physically separate one from the other as related to a respective one of said X and Y coordinates.