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:
Jan. 01, 1991
Filed:
Feb. 21, 1989
Ikio Yoshida, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
In order to perform voice-switched telephoning, a hands-free telephone includes a speaker, a microphone, a receive variable attenuator (R-ATT), a transmit variable attenuator (T-ATT), a receive signal detector, a transmit signal detector and an attenuation control circuit. The telephone also includes an auxiliary control circuit which prevents the output of the transmit signal detector from reaching the attenuation control circuit during a transient period between a call origination and the beginning of a conversation. During the transient period, only the speaker is enabled to output a ringback tone therethrough. When the output level of the transmit signal detector exceeds a predetermined level, the auxiliary control circuit passes the output of the transmit signal detector to the attenuation control circuit to start the voice-switched telephoning. Once the auxiliary control circuit passes the output of the transmit signal detector, it holds this state until the conversation finishes.