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:
Oct. 03, 2000
Filed:
Nov. 20, 1998
Matsushita Electric Industrial Co., Ltd., Osaka-fu, JP;
Abstract
A welder has an electromagnetic switch for turning on and off the power to be supplied to the welder, a control circuit for controlling the turn on and off of this switch according to a starter signal that starts the welder and self-holding circuit for self-holding the switch. This self-holding circuit releases the switch from the self-holding when a voltage of the control circuit lowers to not more than a turn-on voltage of the switch. Therefore, when an applied voltage decreases too low to maintain the turn-on status, the switch is released from its self-holding. A voltage can thus never be applied again to the control circuit unless the starter signal is once turned off. As a result, a coil of the switch is completely free from being burnt out. Also current can be cut off when a temperature of the coil of the switch rises to not less than a given value. Therefore, if an abnormal temperature of the coil is sensed, the coil current is cut off. As a result, the coil of the switch is completely free from being burnt out.