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:
Apr. 27, 1999
Filed:
Dec. 23, 1997
Matsushita Electric Works, Ltd., Osaka, JP;
Abstract
A transformer-isolated power transfer apparatus included in a power supply body and a device body that are removably coupled together. The power supply body contains a primary winding and a secondary winding for transmitting electrical power. The device body contains an induction winding and a load. When the power supply body and device body are coupled together, the secondary winding in the power supply body is electromagnetically inductively coupled to the induction winding provided in the device body to transfer power from the power supply body to the device body via electromagnetic inductive coupling. The apparatus further includes detection circuitry that detects when the power supply body and the device body are coupled together. The power supply body further contains an oscillation drive circuit that drives the primary winding in the power supply body in an intermittent oscillation mode of operation when the detection circuitry detects that the power supply body is not coupled to the device body, and that drives the primary winding in the power supply body in a continuous oscillation mode of operation when the detection circuitry detects that the power supply body is coupled to the device body. During the intermittent oscillation mode of operation, the oscillation on period is controllably varied in response to variations in an input voltage in a manner such as to maintain an average power transmitted from the power supply body to the device body at a substantially constant level. In this manner, the detection circuitry can reliably detect when the power supply body and the device body are coupled together despite variations in the input voltage.