×

Small electronic apparatus

  • US 4,922,527 A
  • Filed: 02/07/1989
  • Issued: 05/01/1990
  • Est. Priority Date: 07/15/1988
  • Status: Expired due to Fees
First Claim
Patent Images

1. A portable telephone comprising:

  • key input means having a plurality of keys for dialing a selected telephone number;

    sound generator means for generating sounds of distinguishable tones related to the identity of actuated keys of the key input means in response to control signals in a predetermined frequency range;

    means for generating dual-tone multi-frequency key identification signals in response to the actuation of each respective key of said key input means, said dual-tone multi-frequency signals having a frequency range within a standard telephone service band outside of the predetermined frequency range to which said sound generator means is responsive; and

    converter means for frequency shifting said dual-tone multi-frequency signals into control signals within said predetermined frequency range, and for applying said frequency-shifted control signals to said sound generator means.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×