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. 30, 2002
Filed:
Jul. 06, 2000
Katsutoshi Katoh, Tokyo-to, JP;
Yasuharu Yamada, Shiga-ken, JP;
Masaki Kobayashi, Tokyo-to, JP;
Takayuki Morino, Yamato, JP;
International Business Machines Corporation, Armonk, NY (US);
Abstract
A ventilation fan for a PC has a plurality of blades disposed around a rotary hub. Each blade is shaped differently from the others to an extent that the air volume handling capacity of the blades is not substantially diminished. The noise level generated by a fan in a specific frequency range is caused by the change in air pressure and is attributable to the symmetry of the fan blade shapes. By altering the shape of the individual blades, the noise level due to pressure change is attenuated. Each blade slightly differs in shape from the others to eliminate air pressure changes. The noise level of the fan is suppressed within an allowable range even when the number of blades and the rotational speed of the fan are increased for better air flow. Preferably, the shape of each blade is varied from the others by putting an adhesive such as putty on the front surface and/or the back surface thereof near the hub. In addition, by putting an adhesive or putty on the front surface and/or the back surface of the blade entirely, the shape of the blade is varied from the others.