×

Apparatus and method for incoming call detection and alarm circuitry for cellular telephones

  • US 5,729,589 A
  • Filed: 12/14/1995
  • Issued: 03/17/1998
  • Est. Priority Date: 12/14/1995
  • Status: Expired due to Fees
First Claim
Patent Images

1. An apparatus, monitoring the electrical power demands made by operation of a cellular telephone on a source of electrical power, for indicating an incoming telephone call to a user, comprising:

  • monitoring means operatively coupled to the source of electrical power for providing an electrical state signal representative of the electrical current being drawn by operation of the cellular telephone;

    means, operatively coupled to said monitoring means to receive said electrical state signal, for generating a voltage state signal having a value representative of the electrical current being drawn by the operation of the cellular telephone from the source of electrical power;

    status determination means for receiving and monitoring said voltage state signal and for generating a powered up state signal whenever the value of said voltage state signal increases from a first selected lower value to a first selected higher value for a first preselected period of time;

    incoming call detection means for receiving said powered up state signal and monitoring said voltage state signal, and for generating an alarm start signal whenever said powered up state signal is present and said voltage state signal is representative of a first selected current transient in the current being drawn by the cellular telephone for a second preselected period of time;

    alarm means operative upon receipt of said alarm start signal for indicating an incoming call to a user;

    alarm cutoff means for monitoring said voltage state signal and disabling said alarm means from further operation whenever the value of said voltage state signal is representative of a second selected current transient in the current being drawn by the cellular telephone; and

    ,cutoff means for monitoring said voltage state signal and disabling said status determination means from further operation whenever the value of said voltage state signal drops below a preselected cutoff value.

View all claims
  • 2 Assignments
Timeline View
Assignment View
    ×
    ×