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Electronic combination door lock with dead bolt sensing means

  • US 4,148,092 A
  • Filed: 08/04/1977
  • Issued: 04/03/1979
  • Est. Priority Date: 08/04/1977
  • Status: Expired due to Term
First Claim
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1. An electronic combination lock for use with a door including, in combination:

  • (a) a dead bolt on said door manually operable by an outer turning knob;

    (b) an electronic circuit for comparing an input code with a stored code and generating an enabling signal only if said input code is the same as said stored code;

    (c) restraining means responsive to said enabling signal to move from a first position locking said outer turning knob from being manually turned to retract said dead bolt, to a second position releasing said outer turning knob so that said outer turning knob can be manually turned to retract said dead bolt to unlock said door;

    (d) bolt position sensing means for sensing a change in the position of said bolt, said restraining means being responsive to said bolt position sensing means to return to said first position when said bolt is manually extended by said outer turning knob to lock said outer turning knob from being manulaly turned to retract said dead bolt;

    (e) battery means for said electronic circuit to provide said enabling signal and operation of said restraining means, manual retraction of said dead bolt avoiding the necessity for expending any battery power to retract said dead bolt whereby less battery drain results than would be the case were the bolt electrically retracted.

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