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. 04, 2008
Filed:
Nov. 21, 2003
Shinji Makimura, Kitakatsuragi-gun, JP;
Hiroshi Kido, Hirakata, JP;
Shingo Masumoto, Hirakata, JP;
Yuji Kumagai, Osaka, JP;
Akira Nakajo, Kyoto, JP;
Shinji Makimura, Kitakatsuragi-gun, JP;
Hiroshi Kido, Hirakata, JP;
Shingo Masumoto, Hirakata, JP;
Yuji Kumagai, Osaka, JP;
Akira Nakajo, Kyoto, JP;
Matsushita Electric Works, Ltd., Osaka, JP;
Abstract
A ballast for an electrodeless discharge lamp includes a high frequency power supply that supplies a high frequency electric power to an induction coil for operating the lamp. A dimmer controller generates a control signal in response to a dimmer command designating a varying dimming ratio. The control signal defines a first period Ton in which the power supply is controlled to apply a coil voltage of a first level Vto the induction coil for operating the lamp. The first period is followed by a second period Toff in which the power supply is controlled to apply the coil voltage of a second level Vthat is lower than the first level and fails to sustain the lamp. The control signal defines, between the second period and the first period, a starting period Tst in which the coil voltage increases continuously for smooth transition from an off-condition to an on-condition of the lamp.