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:
Aug. 25, 1987
Filed:
Mar. 19, 1986
Mead C Killion, Elk Grove Village, IL (US);
Industrial Research Products, Inc., Elk Grove Village, IL (US);
Abstract
A sub-miniature power amplifier for hearing aids configured to be completely self-contained and to fit within the user's ear features a Class D amplifier stage providing a peak-to-peak output voltage greater than the power supply voltage. By configuring all signal elements as digital units, circuit balance is readily maintained. A substantial economy of battery drain is achieved while preserving a low value of distortion at low signal levels. Oscillator frequency is governed by a single resistance element. The amplifier and an optional efficiency-improving inductor can be accommodated entirely within the residual volume of the motor chamber of a state-of-the-art earphone housing. Pulse feedback networks are provided to achieve positive stable latching of each output pulse throughout its duration without producing significant pulse duration distortions.