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:
Jun. 30, 1981
Filed:
Aug. 20, 1979
Milton L Embree, Reading, PA (US);
David C Goldthorp, Reading, PA (US);
David R Vogelpohl, Indianapolis, IN (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
An electronic tone ringer responds to ringing signals on a telephone line while being unresponsive to dialing pulses or other signals on the line. Powered directly from the telephone line the ringer uses current sources (223-226) to provide a high impedance to the ringer circuitry and an insensitivity to line voltage variations so that reliable operation of the ringer is maintained on long loops and with multiple ringers terminated on the line. A multitone signal for activating an electroacoustic transducer (300) is provided by frequency modulating a single oscillator (500) within the tone ringer.