The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 18, 1976
Filed:
Apr. 10, 1975
David P Sidlauskas, San Jose, CA (US);
Schlage Electronics, Inc., Sunnyvale, CA (US);
Abstract
An electronic recognition and identification system for identifying one of a plurality of electrically coded keys, each having at least one tuned electrical circuit which is resonant at at least one of a plurality of predetermined frequencies. The system comprises a sweep oscillator for generating an alternating current signal. The alternating current signal has a frequency which varies with time over a range of frequencies including the plurality of predetermined frequencies. A condition pulse generating network is connected to the oscillator and produces a condition pulse when one of the keys is proximate thereto and when the frequency of the alternating current signal passes through its predetermined frequency. A plurality of reference pulse generating circuits are selectively connected to the oscillator by a sequential multiplexer. Each reference pulse generating circuit is responsive to the alternating current signal and is operative to produce a reference pulse when the frequency of the alternating current signal passes through one of the plurality of predetermined frequencies. A control circuit is responsive to the condition pulses and the reference pulses and is operative to produce a control signal when there is time coincidence between those pulses.