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:
Mar. 30, 1979
Tokyo Shibaura Denki Kabushiki Kaisha, Kawasaki, JP;
Abstract
A telephone exchange comprises a plurality of central office trunk circuits, a plurality of line circuits, a plurality of switching circuits coupled to transmission paths of the trunk and line circuits, a plurality of switching circuits coupled to the reception paths of the trunk and line circuits, a variable attenuator having one end coupled commonly to the switching circuits that are coupled to the transmission path, a conference circuit coupled to the variable attenuator and the switching circuits that are coupled to the reception paths, a control circuit which controls both groups of switching circuits and the variable attenuator in time-sharing fashion thereby to provide speech paths in time-sharing fashion between selected ones of the central office trunk circuits and line circuits and which controls in time-sharing fashion the attenuation factor of the variable attenuator for each speech path established. The telephone exchange further comprises another variable attenuator which is coupled between the conference circuit and the switching circuits coupled to the reception paths and whose attenuation factor is controlled by the control circuit in time-sharing fashion.