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:
Nov. 22, 1983
Filed:
Sep. 25, 1981
Setsuo Norioka, Akishimashi, JP;
JEOL Ltd., Tokyo, JP;
Abstract
A control apparatus according to this invention is installed between an intensity specifying circuit and an excitation current source for a magnetic lens or deflecting coil. The intensity specifying circuit generates a target signal (B) corresponding to the desired magnetic flux density (B) in a magnetic lens or deflecting coil. The excitation current source outputs a current (I) which produces the desired flux density (B). Due to the effects of hysteresis the ferromagnetic yoke adjacent the lens or deflecting coil, the relationship between the target signal (B) and current (I) is nonlinear. The control apparatus has a memory in which data defining the hysteresis characteristics of the lens or coil being controlled has been stored. The control means saves the present intensity specifying signal (the old target signal) and the most recent reverse-value signal (the last target signal proceeded and followed by target signals, both of which are higher or both of which are lower than the reverse-value signal) and with the new target signal calculates the change in current (.DELTA.I) required to produce the desired flux density and commands the excitation current source to output the corresponding current. The effects due to hysteresis of the ferromagnetic yoke are dealt with by the control apparatus facilitating computer control of the electromagnetic lens or deflecting means.