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:
Jul. 25, 2000
Filed:
Jun. 26, 1997
Peter Vaclavik, Plano, TX (US);
Tsuyoshi Ueshima, Plano, TX (US);
Serdar Kiykioglu, Plano, TX (US);
Mark Bolla, Richardson, TX (US);
Fujitsu Network Communications, Inc., Richardson, TX (US);
Abstract
A ring trip detector has a voltage difference detector with first and second inputs, for supplying an off-hook signal upon detection of a voltage difference. The ring trip detector also has a switch extending between the first and second inputs of the voltage difference detector. The ring trip detector detects when a telephone current starts to flow through a sensing resistor having first and second ends and to a telephone set. The switch closes upon an initial current flow through the sensing resistor and then opens. The ring trip detector has a pulse generating mechanism having two inputs respectively connected to the first and second ends of the sensing resistor. The pulse generating mechanism has an output and generates a pulse at the output when current starts to flow through the sensing resistor. The switch has a trigger connected to the output of the pulse generating mechanism for closing the switch when the pulse is generated. A differentiator mechanism may be used as the pulse generating mechanism. Such a differentiator mechanism may have a resistor and a capacitor connected in series between the first end of the sensing resistor and the trigger of the switch, and a resistor connected between the second input of the voltage difference detector and the trigger of the switch. Alternatively, a differentiator/integrator mechanism may be used as the pulse generating mechanism.