Back to results
US 4,481,446 AGranted
Metal vapor discharge lamp
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorsMichihiro Tsuchihashi, Katsuya Otani, Ryo Suzuki
Life of this patent
Estimating the term…
Abstract
In a metal vapor discharge lamp for operating it by high voltage generated in the actuation of a heat sensitive switch means in an outer bulb, a relatively low pressure of a sealed gas or mercury is sealed in the outer bulb to operate the heat sensitive switch means in the gas atmosphere to control the surge voltage to a desired degree whereby the discharge lamp is operated without failure and the insulation breakdown of a ballast and an operation circuit is prevented.
Claims10
A metal vapor discharge lamp which comprises:
- (a) an outer bulb;
- (b) electric circuit means disposed in said outer bulb, said electric circuit means including;
- (i) an arc tube;
- (ii) a first heat-sensitive switch means connected in parallel with said arc tube;
- (iii) heating means disposed adjacent said first heat-sensitive switch means, said heating means being connected in series with said first heat-sensitive switch means;
- (iv) a starting aid disposed adjacent said arc tube and extending along the longitudinal direction of said arc tube;
- and
- (v) a second heat-sensitive switch means connected in series with said starting aid;
- and
- (c) a gas at a subatmospheric pressure within the range from 10.sup.-4 to 20 Torr sealed in said outer bulb, whereby:
- (d) when electricity is initially supplied to said electric circuit means when the metal vapor discharge lamp is turned on:
- (i) said heating means heats said first heat-sensitive switch means, causing said first heat-sensitive switch means to open and thereby causing a transitory voltage surge through said arc tube which initiates discharge of the lamp, and
- (ii) said starting aid is energized, contributing to the initiation of the discharge of the lamp;
- (e) after discharge of the lamp has begun:
- (i) the heat generated by said arc tube heats said second heat-sensitive switch means, causing said second heat-sensitive switch means to open and thereby turning off said starting aid, and
- (ii) the heat generated by said heating means and said arc tube insures that said first heat-sensitive switch means remains open during the discharge of the lamp;
- and
- (f) the relatively low-vacuum gas present in said bulb moderates the transitory surge voltage which would be experienced by said arc tube if a conventional high vacuum were present in said outer bulb.
15 more elements
Dependencies are inferred from the claim text.