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:
Jan. 27, 1981
Filed:
Apr. 11, 1979
Shigeru Yoshizawa, Tokorozawa, JP;
Hirokazu Aoki, Hachioji, JP;
Shinsaku Chiba, Mobara, JP;
Koichi Mayama, Mobara, JP;
Takashi Toyooka, Kokubunji, JP;
Nobuo Saito, Mitaka, JP;
Hitachi, Ltd., , JP;
Abstract
The present invention provides an improved method and apparatus for driving a magnetic bubble device, in which a d-c voltage supply and drive coils are connected to a bridge circuit consisting of four bi-directional switches, and alternating currents with steps (such as currents consisting of triangular waves or trapezoidal waves) are produced in the drive coils by suitably controlling the turn on or off of the bi-directional switches. As a result, the d-c level in the alternating current is not shifted by the variation in width of pulses which control the opening and closing of the bi-directional switches, and the magnetic bubble device is provided with a greatly improved operation margin.