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. 21, 1998
Filed:
Jan. 10, 1995
James C Sprout, Los Altos, CA (US);
Jerome M Mix, Redwood City, CA (US);
The Watt Stopper, Santa Clara, CA (US);
Abstract
A control circuit for controlling the light output level of a dimmable fluorescent light ballast such as the Mark VII ballast manufactured by Advance Transformer, Inc. The circuit operates from power supplied by the Mark VII ballast through a 300 to 500 microamp DC current loop. The control circuit includes a photo sensor that detects the level of ambient light in a room, and in response to the detected light level, the circuit sets a voltage level from 2 and 10 volts between the two output leads for the current loop on the ballast. At 2 volts, the light is at its dimmest level, which is 20 percent of its maximum brightness, while at 10 volts, the light is at the 100 percent level. Between 2 and 10 volts, the light's brightness is set on a linear scale between 20 and 100 percent.