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. 21, 1989
Filed:
Sep. 22, 1987
Shoji Kato, Tokyo, JP;
Takeshi Tomita, Tokyo, JP;
Jeol Ltd., Tokyo, JP;
Abstract
In a conventional electron beam-producing apparatus, a field emission gun is combined with an accelerating tube. An electrostatic lens focuses the electron beam diverging from the emitter. This conventional apparatus needs a large power supply for applying potentials to the electrodes of the lens and to the accelerating electrodes. Also, it is difficult to make stationary the position at which the crossover point of the electron beam is imaged. The present invention makes use of voltage-dividing resistors to produce fractions of the accelerating voltage. These fractions of the voltage are applied to the electrodes of the electrostatic lens and to various electrodes. This permits the use of a power supply that is smaller in size than conventional. The number of the used voltage-dividing resistors is increased or decreased, depending on the accelerating voltage. This makes it possible to fix the position of the crossover point imaged by the electrostatic lens.