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. 03, 1998
Filed:
Dec. 20, 1996
Oleg Popov, Needham, MA (US);
Jakob Maya, Brookline, MA (US);
Koichi Kobayashi, Needham, MA (US);
Edward K Shapiro, Levington, MA (US);
Matsushita Electric Works Research & Development Laboratories Inc., Woborn, MA (US);
Abstract
An electrodeless inductively-coupled fluorescent lamp which operates at ro frequency comprising a bulbous envelope (1) filled with rare gas and metal vapor. A reentrant cavity (4) and an induction coil (6) are disposed in the cavity (4). The inner walls of the envelope (1) and the cavity (4) have a protective coating (3) and a phosphor coating (2). A metal Faraday cylinder (12) welded to the lamp base (13) is disposed between the cavity (4) and the coil (6) to reduce capacitive RF voltage between the coil and the plasma to improve lamp maintenance and remove heat. A tubulation (16) is disposed on the lamp axis to evacuate the envelope (1). The proximal end of the tubulation (16) has an expansion (20) with the volume (23) where the initial capacitive discharge is ignited. The RF coil voltage needed for the ignition of the capacitive discharge in the expansion area (23) is substantially lower than that needed for the ignition of the capacitive discharge in the area (14) along the inner cavity walls (4) to decrease the lamp starting voltage. In one of the embodiments of the present invention the expansion is conically shaped and in another it is cylindrically shaped and is used to generate the inductive plasma to increase the light generation in the top part of the bulb (28) and improve light output through the bulb top surface (27).