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:
May. 30, 1989
Filed:
Feb. 26, 1988
Pradeep M Bhagwat, Baltimore, MD (US);
Donald E Elson, Baltimore, MD (US);
Richard T Walter, Baldwin, MD (US);
Black & Decker Inc., Newark, DE (US);
Abstract
A corded/cordless dual-mode power-operated device, such as a household vacuum cleaner, can be operated in corded mode from a conventional power source and in a cordless mode using energy provided from an internal rechargable battery and which includes an internal battery charger for recharging the battery when the device is in its corded mode. The internal charger includes a voltage converter that converts input source current to a relatively high DC current that is chopped at a comparatively high frequency, e.g., 25 KHz, by switching devices. The high-frequency, high voltage current is presented to a step-down transformer with the stepped-down output rectified to provide a low-voltage DC suitable for recharging the internal battery when the device is in its corded mode. The voltage converter advantageously provides for the high efficiency conversion of the input energy to meet the charging current demands of the internal battery in a physically compact device.