English: F. Blaschke's US3824437 'Method of Controlling Asynchronous Machines', image of the patent with no notice of exception so is in the public domain
Ngày
Nguồn gốc
US Patent 3824437
Tác giả
Felix Blaschke
Giấy phép
Public domainPublic domainfalsefalse
The text and illustrations of US patents published before March 1, 1989 are in the public domain unless the patent text contains a specific notice that portions are copyrighted. See 37 CFR 1.71(d), 37 CFR 1.84(s)
The original patent contains no such notice, so its contents are in the public domain. Note: This only applies to images published before March 1, 1989. Patents published after that date are most likely copyrighted, unless in the public domain for another reason, such as {{PD-ineligible}}.
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