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:
Oct. 09, 1984
Filed:
Aug. 27, 1982
Kazuo Watanabe, Takasaki, JP;
Yasuo Kominami, Takasaki, JP;
Yoshiyuki Takizawa, Tokorozawa, JP;
Akira Haeno, Iruma, JP;
Hitachi, Ltd., Tokyo, JP;
Pioneer Electronic Corporation, Tokyo, JP;
Abstract
A noise reduction system is provided which can operate as either a Dolby B-type or C-type system. In either case, an input signal is applied to the variable impedance of a high-level side chain through an identical shared filter circuit network. The high-level side chain has two voltage-current converters for controlling the variable impedance. By substantially inhibiting the operation of one of the two converters, the system operates as a C-type Dolby system. On the other hand, when the system operates as a B-type Dolby system, a bias current is applied to each of the two converters during periods of no input signal. This bias current is about half of a minute bias control current which is applied during no signal periods to the single converter used when the system operates as the C-type Dolby system.