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Key input apparatus

  • US 4,918,634 A
  • Filed: 02/22/1988
  • Issued: 04/17/1990
  • Est. Priority Date: 02/23/1987
  • Status: Expired due to Fees
First Claim
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1. A key input apparatus with a plurality of key switches for outputting respective information, said key input apparatus comprising:

  • a variable resistance circuit including a plurality of key units connected with each other in parallel and a pair of terminals, each key unit including a key switch and a resistance element connected with the key switch in series,a voltage generating unit including a power source connected with one terminal of said variable resistance circuit and a resistance element connected with said other terminal of said variable resistance circuit in series for generating an analog voltage corresponding to a resistance value of said variable resistance circuit, andan analog-to-digital converter for converting said analog voltage into a digital signal.

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