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:
Jan. 19, 1999
Filed:
Jun. 10, 1997
Sony Corporation, Tokyo, JP;
Abstract
A speaker device driving drive coils of a speaker such as an electromagnetically coupled speaker by digital sound signals, where a primary coil of the speaker unit is constituted by 15 pieces of coils, the coils are made to correspond to respective bits excluding MSB of a digital sound of 16 bits issued from a serial/parallel converter, each of the coils are connected in a bridge connection to 4 pieces of FETs respectively opposed to each other and constant current sources are connected to the bridge connection portions whereby a coil drive circuit is constituted, currents from the constant current sources are respectively supplied to the coils and a variable resistor is adjusted by which voltages are changed and the currents of the constant current sources are commonly controlled whereby the volume of the speaker is finely driven.