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. 16, 1997
Filed:
Feb. 27, 1996
Mikio Oda, Yawata, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A low frequency audio conversion circuit for converting the frequency of low frequency audio components. An input audio signal includes a low frequency audio component lower than the frequency a speaker can reproduce. The low frequency audio component is filtered and extracted by a low pass filter and full-wave rectified to generate even-numbered harmonics of the low frequency audio component. Secondary harmonics are extracted from the even-numbered harmonics and added to the input audio signal after being amplified to an appropriate level. When a speaker whose low frequency sound reproduction characteristics are poor is used, and a low frequency component lower than the frequency the speaker can reproduce is supplied, the low frequency audio component is reproduced as secondary harmonics which fall within the frequency range of the speaker. Thus, the low frequency audio component is compensated, and a powerful sound is reproduced at a low cost without degrading the sound.