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:
Jun. 15, 1982
Filed:
Jun. 10, 1980
Hitachi, Ltd., Tokyo, JP;
Abstract
A low pressure metal vapor discharge lamp has a double-tube type discharge vessel consisting of a fully closed outer glass bulb and an inner glass tube substantially coaxially disposed in the outer glass bulb, the inner glass tube being closed at its fixed end and opened at its free end. The space within the discharge vessel is filled with a small amount of a metal and a rare gas of a low pressure. A single cathode is disposed within the space inside the inner glass tube, while a plurality of anodes are disposed in the annular space between the inner glass tube and the outer glass bulb. According to the invention, a number of discharge channels corresponding to that of the anodes are formed between the single cathode and respective anodes, via the opening end brim of the inner glass tube. In operation, anode oscillations take place alternately in respective anodes to cause a self-excitation switching operation, so that a plurality of plasmas are formed. Further, in order to avoid flickering of the output light of the lamp, which is attributable to the irregular fluctuation of the plasmas, means are provided for stably fixing the discharge channels to respective constant positions. The means for fixing the discharge channels may be in the form of axial notches formed in the opening end brim of the inner glass tube, corresponding to the anodes, or a partition plate disposed at the opening end of the inner glass tube and adapted to separate the discharge channels from each other.