Touch detection apparatus and touch point detection method

摘要

A touch detection apparatus is provided, in which a touch panel is implemented with four surrounding edges. Three of the edges are embedded with retro-reflection materials. Light sources and pinholes are deployed on both corners of the touch panel, allowing reflections from the three edges to be projected on light sensors through the pinhole. The images projected on the light sensors are analyzed to determine coordinates of one or more contact points on the touch panel.

主权项

1. A touch detection apparatus for detecting a location of a touch point touched by an object, comprising:
a touch panel for receiving contact from at least one object; a first edge, a second edge, a third edge and a fourth edge for encircling the touch panel, wherein the first edge is opposite to the second edge and the third edge is opposite to the fourth edge, and the first edge, the second edge and the third edge comprise retro-reflection materials; a first pinhole and a first light source disposed on the corner of the first edge and the fourth edge for emitting a first light beam toward the second edge and the third edge to generate a first reflection light; a second pinhole and a second light source disposed on the corner of the second edge and the fourth edge for emitting a second light beam toward the first edge and the third edge to generate a second reflection light; a first light sensor module disposed at the outer edge of the touch panel and separated from the first pinhole by a predetermined distance for detecting a first image projected on the first light sensor module by the first reflection light through the first pinhole; a second light sensor module disposed at the outer edge of the touch panel and separated from the second pinhole by the predetermined distance for detecting a second image projected on the second light sensor module by the second reflection light through the second pinhole; a third pinhole disposed on the middle of the fourth edge; a third light sensor module disposed at the outer edge of the fourth edge towards the third pinhole for detecting a third image projected on the third light sensor module by the first reflection light and the second reflection light through the third pinhole, wherein the third light sensor module comprises a left light sensor and a right light sensor, and the left light sensor, the right light sensor and fourth edge form a closed area; and a calculation unit coupled to the first light sensor module, the second light sensor module and the third light sensor module for receiving the first image, the second image and the third image, to perform an image analysis to determine a coordinate of a touch point where the touch panel is contacted by the at least one object, wherein the third image is obstructed by the first object and the second object to generate two obstructed points thereon, and the calculation unit substitutes any two obstructed locations of the obstructed points on the first image and the third image into a angle formula and performs the conversion operation to obtain a second set of possible solutions which comprises four coordinate candidates of the touch points, and the calculation unit determines the coordinates of the touch points touched by the first object and the second object in the intersection of the first set of possible solutions and the second set of possible solutions.