Fingertip detection for camera based multi-touch systems
First Claim
Patent Images
1. A touch detection system comprising:
- a light guiding sheet having a touch surface and a rear surface;
a source arranged to couple light into an edge of the light guiding sheet, such that the light is totally internally reflected within a working area of the light guiding sheet;
a reflective layer in proximity to the rear surface of the light guiding sheet;
a display surface in proximity to the reflective layer;
a detector arranged in front of the touch surface of the light guiding sheet and opposite to the reflective layer, to detect light emitted by the source, scattered as a result of a touch event and reflected by the reflective layer; and
a computing-based device comprising;
a processor;
an interface to the display surface;
an interface to the detector; and
a memory arranged to store executable instructions to cause the processor to;
perform image analysis on a signal from the detector to identify a touch event, the image analysis comprising;
generating an area of interest inside the working area of the light guide sheet;
filtering the signal to remove all data outside the area of interest; and
converting the signal into a binary image using a threshold.
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Abstract
Touch detection systems and methods are described. The system comprises a light guiding sheet, a light source, a reflective layer and a detector. When a fingertip or other suitable object is pressed against the light guiding sheet, light which is undergoing total internal reflection within the sheet is scattered. The scattered light is reflected by the reflective layer and detected by the detector. In an embodiment, the light is infra-red light. The touch detection system may, in some embodiments, be placed on a display and the touch events used to control the display.
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Citations
16 Claims
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1. A touch detection system comprising:
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a light guiding sheet having a touch surface and a rear surface; a source arranged to couple light into an edge of the light guiding sheet, such that the light is totally internally reflected within a working area of the light guiding sheet; a reflective layer in proximity to the rear surface of the light guiding sheet; a display surface in proximity to the reflective layer; a detector arranged in front of the touch surface of the light guiding sheet and opposite to the reflective layer, to detect light emitted by the source, scattered as a result of a touch event and reflected by the reflective layer; and a computing-based device comprising; a processor; an interface to the display surface; an interface to the detector; and a memory arranged to store executable instructions to cause the processor to; perform image analysis on a signal from the detector to identify a touch event, the image analysis comprising; generating an area of interest inside the working area of the light guide sheet; filtering the signal to remove all data outside the area of interest; and converting the signal into a binary image using a threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of detecting touch events comprising:
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projecting light into a light guiding sheet such that it undergoes total internal reflection; detecting, by a detector arranged in front of a first surface of the light guiding sheet, light scattered by a touch event on the first surface of the light guiding sheet and reflected by a reflective layer in proximity to a second surface of the light guiding sheet; generating a signal representative of the light detected; performing image processing on the signal to identify a touch event, the image processing comprising; generating an area of interest inside an area of the light guide sheet; filtering the signal to remove all data outside the area of interest; and converting the signal into a binary image using a threshold. - View Dependent Claims (13, 14)
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15. A touch sensitive user input device comprising:
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a light guiding layer; a source arranged to couple light into an edge of the light guiding layer; a reflective layer in proximity to a first surface of the light guiding layer and arranged to reflect light scattered by a user touching a second surface of the light guiding layer; a detector arranged in front of the second surface of the light guiding layer, the detector to detect light reflected by the reflective layer; and a computing-based device comprising; a processor and memory arranged to store executable instructions to cause the processor to; generate a signal representative of the light detected; and perform image processing on the signal to identify a touch event, the image processing comprising; generating an area of interest inside an area of the light guiding layer; filtering the signal to remove all data outside the area of interest; and converting the signal into a binary image using a threshold. - View Dependent Claims (16)
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Specification