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:
Dec. 10, 1996
Filed:
Mar. 17, 1994
Omura Hideaki, Ibaraki, JP;
Masayuki Wakamiya, Suita, JP;
Nobuyoshi Takeuchi, Osaka, JP;
Munehiro Tabata, Ibaraki, JP;
Matsushita Electric Industrial Co., Ltd., Osaka-fu, JP;
Abstract
A metal halide lamp is employed, as a light source, in an optical device such as, for example, an illuminator or an image display. The optical device includes a discharge tube filled with mercury, at least one rare gas, and at least one metal halide, and a pair of electrodes spaced from each other and enclosed in the discharge tube. The optical device also includes an electric circuit, electrically connected to the pair of electrodes, for starting the discharge tube by applying thereto a higher voltage than a voltage to be applied at a steady state to thereby cause an arc discharge in the discharge tube. When the lamp is turned off, power supply thereto from the electric circuit is temporarily interrupted, and when the lamp cools after a first time interval has elapsed subsequent to the interruption of the power supply, a starting voltage is applied to the lamp via the pair of electrodes for a second time interval to cause redischarge. Thereafter, the power supply to the lamp is interrupted after the second time interval has elapsed, to thereby turn off the lamp.