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. 13, 2005
Filed:
Dec. 26, 2001
Applicant:
Chris Goodings, Fleet, GB;
Inventor:
Chris Goodings, Fleet, GB;
Assignee:
VTech Communications, Ltd., Tai Po, HK;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M019/04 ;
U.S. Cl.
CPC ...
Abstract
A digital circuit for driving an audio transducer that provides consistent tonal quality over a range of volume levels, without requiring a variable gain analog amplifier. A fixed amplitude ringer tone is multiplied, or amplitude modulated, by a higher frequency digital pulse train to produce a transducer driving signal. The timbre of the transducer driving signal is similar to that of the fixed amplitude ringer tone, but the volume of the sound produced by the transducer varies with the mark-space ratio of the pulse train.