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:
Nov. 03, 2015
Filed:
Nov. 20, 2013
Rohm Co., Ltd., Ukyo-Ku, Kyoto, JP;
Toshiya Suzuki, Kyoto, JP;
Yuki Gohara, Kyoto, JP;
ROHM CO., LTD., , JP;
Abstract
According to the voltage Vthat occurs at one end of at least one of multiple coils of a fan motor, a back electromotive force detection circuit generates a detection signal BEMFasserted in a cyclic manner when a fan motor is stably rotating. A lock protection circuit detects a lock state of the fan motor rotor. A period detection unit measures the detection signal BEMFperiod. A synchronization pulse generating circuit generates a synchronization pulse having a period that is 1/N (N represents an integer of 2 or more) of that of the detection signal BEMFmeasured in a previous cycle. A lock judgment unit counts the synchronization pulse in increments of cycles of the detection signal BEMF. When the count value exceeds a predetermined threshold value M (M represents an integer of 2 or more) which is greater than N, the lock mode judgment signal is asserted.