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:
Sep. 05, 1989
Filed:
Sep. 09, 1988
Pioneer Electronic Corporation, Tokyo, JP;
Abstract
An automatic volume control apparatus for use in a mobile audio apparatus in which a detection output from a noise detection section is compared with a control output applied to a volume control section, and a capacitor inserted between a control signal input terminal of the volume control section and a reference voltage point is charged/discharged by a current source section with a constant current on the basis of the output of the comparator to thereby make it possible to make the change of volume constant or linear relative to the change of noise level. Also, a control signal for a volume controller is obtained by subtracting a quantity of logarithmic change of an audio signal detection signal obtained from an audio signal detection section relative to a reference value from a value obtained by amplifying, with an amplification factor in a range of 1.5 to 2.5, a quantity of logarithmic change of a noise detection signal obtained from a noise detection section relative to a reference value, whereby the correspondence between levels of low-frequency components of, for example, 10 Hz or less and audible frequency components of in-vehicle noise becomes higher so that it is possible to perform more natural volume control.