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:
Aug. 16, 1988
Filed:
Feb. 28, 1986
Masayuki Tsurusaki, Tokyo, JP;
Yasuji Sato, Tokyo, JP;
Takeshi Horiuchi, Tokyo, JP;
Hisashi Yamada, Kanagawa, JP;
Minoru Tanaka, Tokyo, JP;
Akira Maekawa, Tokyo, JP;
Kabushiki Kaisha Toshiba, , JP;
Abstract
A loud-speaker telephone set includes a switching control circuit to attenuate the incoming signal, during transmission, and to attenuate the outgoing signal, during reception, in order to prevent feedback from the loud-speaker to the microphone. An automatic gain control circuit is added which detects at least one of the incoming signal level and the outgoing signal level and which adjusts the attenuation of both the incoming and outgoing signals so as to reduce the attenuation change between reception and transmission below 20 dB and eliminate the unpleasant sensation, to a user, of large attenuation changes.