Patents Examined by Hina Tong
  • Patent number: 5469133
    Abstract: Vibration of a pager is sensed by a piezoelectric crystal. A buffered output of the crystal is connected through a low pass filter to an input of a retriggerable monostable multivibrator having a period of approximately twenty milliseconds. In response to the twenty millisecond multivibrator being retriggered to provide a recognition pulse having a duration of approximately three seconds, a latch is set. An output of the latch drives an LED circuit that provides a visual indication of a page. In response to the latch being set, an astable multivibrator provides alarm pulses having a duration of approximately eight seconds with a thirty second interval therebetween. The output of the latch and the output of the astable multivibrator drive an audio alarm circuit through a selector switch. When the switch is thrown in one direction, the setting of the latch causes the alarm circuit to provide a continuous audible sound.
    Type: Grant
    Filed: November 29, 1993
    Date of Patent: November 21, 1995
    Inventors: Scott E. Hensler, Scott I. Bergman, Mike P. Costello