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:
Feb. 05, 1985
Filed:
Apr. 19, 1983
Applicant:
Inventor:
Philip T Blenkinsop, Fowlmere, nr. Royston, Hertfordshire, GB;
Assignee:
Other;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
E05F / ;
U.S. Cl.
CPC ...
49 31 ; 49169 ; 119 / ;
Abstract
A control circuit for unlatching a door, particularly a pet door, includes a transmitter coil (L1), a pulse driver (11) for pulse energizing the coil, and a discriminator (12, 13) for detecting a.c. components in the coil current caused by currents induced in an outside tuned circuit brought adjacent the coil, e.g. around the neck of a pet seeking entry, and for comparing the frequency of the a.c. components with a standard. A latch drive circuit (14) responds to the discriminator for operating the door latch if the frequency comparison is satisfactory.