Method and apparatus for downloading information from a controllable light source to a portable information device

摘要

A system for transferring data from a CRT (cathode ray tube) video display monitor on a personal computer to a portable information device such as a multifunction electronic wristwatch. The CRT video display has a video signal generator providing raster scanning of the screen and a program for formatting the binary coded data into blocks of serial data bits, with start bit and stop bit. The blocks of data are supplied to the video signal generator in synchronism with raster scanning of the screen so as to provide an integral number of one or more blocks of data for each vertical frame, and modulated to vary the brightness of the screen and provide scan line segments providing light pulses corresponding to presence or absence of binary coded transmitter pulses. The scan line segments commence at selected screen coordinate locations, such that each successive scan line segment representing a data bit commences at a different temporal position along the scan line than the preceding scan line segment.