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:
Apr. 26, 1994
Filed:
Dec. 14, 1992
Ingo Reichelt, Schwabach, DE;
U.S. Philips Corporation, New York, NY (US);
Abstract
A telephone branch line transmission circuit includes a control device which receives dial pulses and in response thereto controls at least two switching devices arranged between two branch lines to a telephone exchange. A blocking capacitor is coupled to the first switching device. In order to prevent charging of such capacitor from distorting the current supplied from the exchange at the end of a dial pulse, the first switching device is included between the blocking capacitor and one of the branch lines. The connection node thereof with the blocking capacitor is connected to a terminal of a second switching device, another terminal of which is coupled to the second branch line. The control terminal of the second switching device is connected to a storage capacitor. In the off-state of the switching devices no residual direct current can flow from the exchange to charge the blocking capacitor. Consequently, upon termination of a dial pulse, the blocking capacitor cannot distort the current supplied by the exchange. The storage capacitor charges during dial pulses and establishes a high impedance across the branch lines after dialing is completed.