SWITCH SCANNING MEANS FOR USE WITH INTEGRATED CIRCUITS

摘要

SWITCH SCANNING MEANS FOR USE WITH INTEGRATED CIRCUITS B3482 Method and apparatus for generating a digital data word representative of the position of a switch element which is selectively engageable with one of a plurality of driver conductors which are utilized for conducting actuating signals from a source to a data display system of the type having a plurality of display elements for visually indicating alphanumeric data. The display elements have visually perceptible and imperceptible data indicating states and are characterized by a lagging response to either the application or interruption of the actuating signal wherein a turn-on or turn-off transition interval elapses during a change from one state to the other with the preexisting state of the display element appearing to an observer to remain unchanged during the transition interval. The actuating signals are periodically applied during a load energizing interval through one or more of the driver conductors and are interrupted during a sampling interval. The load energizing interval is much longer in duration relative to the duration of the sampling interval, with the duration of the sampling interval being substantially less than the duration of the turn-off transition interval. Each driver conductor is sequentially pulsed during the sampling interval with a strobe signal having a pulse component duration which is substantially shorter than the turn-on time of the display elements. A number of repetitive events are counted which occur during the interval commencing with the first application of a strobe pulse to a driver conductor of the array and terminating with the application of a strobe pulse to the driver conductor engaged in electrical contact with the data input conductor through the movable switch element. The number of repetitive events counted during the sampling interval is proportional to the number of strobe pulses applied to the driver conductors during the sampling interval and is therefore representative of the position of the movable switch element.