Optical touch device and method for detecting touch point

摘要

An optical touch device utilizes two images sensed by two image sensing units, which are diagonal to each other, to determine whether a number of touch points located at a central touch area is equal to 1. When the number of touch points are larger than 1, the optical touch device further utilizes another two images sensed by another two image sensing units, which are also diagonal to each other, to assist in determining the number of touch points located at the central touch area, so as to improve the accuracy of determination.

主权项

1. An optical touch device comprising:
an indication plane having a first edge and a second edge, the first edge being opposite to the second edge; a first image sensing unit and a second image sensing unit separately disposed on the first edge; a third image sensing unit and a fourth image sensing unit separately disposed on the second edge, a central touch area being defined between the first image sensing unit, the second image sensing unit, the third image sensing unit and the fourth image sensing unit, the first image sensing unit and the third image sensing unit being diagonal to each other, the second image sensing unit and the fourth image sensing unit being diagonal to each other; and a processing unit electrically connected to the first image sensing unit, the second image sensing unit, the third image sensing unit and the fourth image sensing unit; wherein when a touch gesture is performed on the central touch area, the first image sensing unit senses a first image, the second image sensing unit senses a second image, the third image sensing unit senses a third image and the fourth image sensing unit senses a fourth image; the processing unit calculates N touch points according to the first image and the third image and determines whether N is equal to 1, N is a positive integer; when N is equal to 1, the processing unit determines that the touch gesture generates one touch point on the central touch area; when N is larger than 1, the processing unit calculates M touch points according to the second image and the fourth image and determines whether N is larger than or equal to M, M is a positive integer; when N is larger than or equal to M, the processing unit determines that the touch gesture generates M touch points on the central touch area; when N is smaller than M, the processing unit determines that the touch gesture generates N touch points on the central touch area.