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:
Feb. 06, 1990
Filed:
Sep. 15, 1987
Hiroyuki Takewa, Kaizuka, JP;
Mitsuhiko Serikawa, Hirakata, JP;
Seiichi Ishikawa, Hirakata, JP;
Sawako Usuki, Kobe, JP;
Yoichi Kimura, Ashiya, JP;
Shuichi Obata, Kyoto, JP;
Matsushita Electric Industrial Co., Ltd., Tokyo, JP;
Abstract
A speaker which is thin but which is capable of providing high-fidelity reproduction and ensuring a suitable level of sound pressure even when it is brought close to a wall. A closed chamber is formed behind one part of a diaphragm mounted in an enclosure, and an open chamber is formed behind another part of the diaphragm. At least one voice coil drive unit is connected to the diaphragm. The phase difference between sounds radiated from the front and rear surfaces of the diaphragm is increased as large as possible by using an acoustic duct for the sound radiated through the open chamber, thereby minimizing cancellation of sounds and improving the sound pressure level.