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:
Oct. 14, 1997
Filed:
Dec. 19, 1994
Johannes T De Hair, Roosendaal, NL;
Lukas Kastelein, Roosendaal, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A low-pressure mercury discharge lamp with a lamp vessel having a first lamp vessel portion (La1) with a first electrode (E11) and a first luminescent layer which radiates white light of a first color temperature during lamp operation and a second lamp vessel portion (La2) with a second electrode (E12) and with a second luminescent layer which radiates white light of a second colour temperature different from the first during lamp operation. The first lamp vessel portion and the second lamp vessel portion are interconnected by a connection which allows a filling of mercury and a rare gas in both portions to pass and together enclose a discharge space. The discharge space contains only one further electrode (E13) for both the first and second lamp vessel portions. Circuit I generates a first current through the first lamp vessel portion and a second current through the second lamp vessel portion and circuit II adjusts the ratio between the effective value of the first current and the effective value of the second current. The first current and the second current are high-frequency currents of changing polarity. The color temperature of the light radiated by the lamp can be adjusted over a comparatively wide range, while the lamp is of a simple construction and has a comparatively high luminous efficacy.