Keypad monitor with keypad activity-based activation

  • US 5,235,635 A
  • Filed: 09/27/1990
  • Issued: 08/10/1993
  • Est. Priority Date: 09/27/1990
  • Status: Expired due to Term
First Claim
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1. In a telephone apparatus having a keypad including a plurality of keypad switches and which includes internal circuitry which is deactivated when in an idle state for conserving power and activated in response to receiving clock signals from an external clock source, a system for activating said telephone apparatus comprising:

  • keypad monitoring means coupled to said plurality of keypad switches for monitoring the condition of said plurality of keypad switches and providing a first output signal in response to a change in the condition of any one of said plurality of keypad switches;

    clock detecting means for detecting the presence and absence of said clock signals and providing a second output signal responsive to detecting the absence of said clock signals; and

    output means coupled to said external clock source and responsive to said first and second output signals for providing an activation signal to cause said external clock source to provide said telephone apparatus with said clock signals.

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