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. 06, 2002
Filed:
Jun. 14, 1999
Philip David Langley, Granite Bay, CA (US);
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A system, such as a computer system, has cooling fans, each having a fan motor and fan blades. The fan motor operates to rotate the fan blades at a variable rotational speed. A frequency generator generates a reference speed signal having a reference frequency and a reference phase. Tachometers measure the variable rotational speeds of the fan blades of corresponding fans and provide corresponding fan speed signals representative of the variable rotational speeds of the corresponding fans. Each fan speed signal has a fan frequency and a fan phase. Motor controllers control the variable rotational speed of corresponding fan blades of corresponding fans based on the reference speed signal and the corresponding fan speed signals.