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:
Mar. 12, 1991
Filed:
Jun. 22, 1988
Susumu Hanyu, Tokyo, JP;
Noboru Kasuga, Tokyo, JP;
Kazumasa Hara, Tokyo, JP;
Shuzo Morimoto, Tokyo, JP;
Janome Sewing Machine Co. Ltd., Tokyo, JP;
Abstract
A method of automatically controlling thread tension in a sewing machine according to which a first thread tension device is provided between an upper thread source and a thread take-up lever, and a second thread tension device is provided between the first tension device and the thread take-up lever. The first thread tension device is operated to apply a constant pressure to the upper thread such that the thread take-up lever is able to draw out the upper thread upon moving upward. The second thread tension device is operated to fixedly hold the upper thread until the thread take-up lever moves upward to an upper dead point thereof through a lower dead point thereof, at which the take-up lever moves downward to supply the upper thread to the needle. The second thread tension device is further operated to effect release of the upper thread when the thread take-up lever reaches the upper dead point thereof and until the thread take-up lever moves downward to a thread supply starting position thereof.