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Characteristics:
Flexible metal contact, height compatible with standard LED displays.
Single sided printed circuit board.
Low cost capacitive transducer, requiring only 4 discrete components per key (patent pending).
Multiplexed operation enables up to 64 keys to be controlled by a standard low cost microcontroller.
500Khz, 5 volt, 50 mA operation.
Front panel up to 6mm ceramic, or up to 2mm plastic.
Software features:
Auto-zero trim to compensate drifts.
Turn-on and differential thresholds.
Adjustable turn-on delay and time-out.
Adjustable stroke speed sensitivity
Advantages:
A capacitive keyboard can be implemented at lower cost than a standard one.
The main control will only use some standard output ports and analog inputs of a general purpose microcontroller.
The standard ports can be shared with the digit selection signal in case of using a LED multiplexed display.
Sophisticated MDL software can make a keyboard very rugged against spurious activation when cleaning the glass surface. |
