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:
Jul. 27, 2004
Filed:
Jun. 24, 2002
Daniel Liu, Hsin Tien, Taipei Hsien, TW;
Other;
Abstract
A relay control circuit is connected between a power source supplying an alternate current and a load to which the alternate current is supplied. The relay control circuit includes contacts for conducting/cutting off the alternate current supplied from the power source to the load. A first zero-crossing detection circuit is connected to the power source and generating a first zero-crossing signal to a control unit having a memory unit storing a time delay parameter. The control unit issues a control signal to energize a coil for actuating the contacts at a time point that leads the zero crossing point of the alternate current a time period equal to the time delay parameter whereby the contacts are actually actuated at a time point corresponding to the zero-crossing point. A second zero-crossing detection circuit is coupled to the load and generates a second zero-crossing signal. In case of deterioration of the performance of the relay, a difference exists between the time of detection of the second zero-crossing signal and the time point of the time delay parameter after the control signal. The difference is used to correct the time delay parameter.