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:
Dec. 16, 2003
Filed:
May. 27, 1999
Bar-Chung Hwang, Taoyuan, TW;
Winbond Electronics Corp., Hsinchu, TW;
Abstract
A telephone signal detecting circuit is provided, which can identify an input signal is a line reversal signal or a ring signal. Providing this telephone signal detecting circuit into a ring detector of a conventional telephone set can share the burden of the microprocessor of the telephone set and lessen the loading of power supply. In this invention, the Schmitt triggers of two different trigger levels are used to respectively detect the voltage change of the first discharge of the capacitor and the ripple signal produced due to the charge of the capacitor by the ring signal. The input signal can be easily identified to be a line reversal signal or a ring signal through a simple flip-flop circuit that can reduce the influence of the bouncing effect. The telephone signal detecting circuit is operated in a static mode and is almost free of power-consumption when it is not working.