Touch input device having power profiling

Claim 1

A touch input device for detecting at least one passive stylus, comprising: an opto-matrix frame having a plurality of optical emitters and oppositely positioned optical detectors disposed in the opto-matrix frame and having an optically transparent bezel adjacent thereto, characterized in that: the plurality of optical emitters are electrically interconnected in a matrix such that the anodes form one side of the matrix and the cathodes form the other side of said matrix; the plurality of optical detectors are electrically interconnected in a matrix such that the anodes form one side of the matrix and the cathodes form the other side of said matrix corresponding emitters and detectors forming emitter-detector pairs; a first driving device is connected to the optical emitters for selectively energizing at least one emitter at at time; a first decoding or selection device is connected to the optical detectors for selectively energizing at least one detector at a time; at least one emitter-detector pair disposed adjacent corners of the optically transparent bezel being connected to means for decreasing the output thereof relative to the remainder of the emitters and detectors thereby minimizing the effects of reflected radiant energy; and a microcomputer interconnected to the first driving device and the first decoding or selection device so as to sequentially energize the first and second driving devices, wherein the microcomputer produces a data output signal which corresponds to the presence or absence of the passive styli.