| 摘要 |
A portable self-contained remote access terminal comprises a matrix display device and a touch screen device having a touch surface which overlies the display device so that the display device can be seen through the touch surface. The touch screen device comprises an array of infrared emitter elements for emitting respective beams over a sensing space, a corresponding array of detector elements for receiving the beams respectively, driver circuits for intermittently and sequentially energizing the emitter elements at a power level at least 10 times the rated constant power level of the emitter elements at a frequency of at least about 20 Hz and at a duty cycle substantially less than about two percent, a multiplexer operative when the emitter element is energized to select the corresponding detector element, and a voltage detector for determining whether the selected detector element is illuminated. The terminal also comprises a data storage device in which data for determining the nature of the display provided by the display device is stored, and in which data provided by way of the touch screen device is stored. A battery pack which is incorporated in the terminal is used to operate the data storage device, the display device and the touch screen device.
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