Short arc high intensity mercury discharge lamp

(19)

(11)

EP 1 416 518 A3

(12)	EUROPEAN PATENT APPLICATION

(88)	Date of publication A3:
	01.07.2009 Bulletin 2009/27

(43)	Date of publication A2:
	06.05.2004 Bulletin 2004/19

(21)	Application number: 03256860.2

(22)	Date of filing: 30.10.2003

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International Patent Classification (IPC):

H01J 61/86^(2006.01)
H01J 61/20^(2006.01)
H05B 37/02^(2006.01)
H01J 61/82^(2006.01)

H01J 61/54^(2006.01)
H05B 41/292^(2006.01)
H01J 61/52^(2006.01)

(84)	Designated Contracting States:
	AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PT RO SE SI SK TR
	Designated Extension States:
	AL LT LV MK

(30)

Priority:

30.10.2002 GB 0225254

(71)	Applicant: GENERAL ELECTRIC COMPANY
	Schenectady, NY 12345 (US)

(72)	Inventors:
	Girach, Mahomed Hanif Leicester LE2 1LU (GB) Preston, Barry, The Arch House Melton Mowbray Leicestershire LE14 2TE (GB) Vulliamy, Michael Justin Leicestershire LE24 2DD (GB) Howe, Stephen Harold Leicester LE67 9QJ (GB)

(74)	Representative: Goode, Ian Roy
	London Patent Operation, General Electric International Inc., 15 John Adam Street London WC2N 6LU London WC2N 6LU (GB)

(54)	Short arc high intensity mercury discharge lamp

(57) A high pressure arc discharge lamp apparatus comprising a lamp (40) and an operating system (42, 44, 46) therefor. The lamp comprises an envelope forming a discharge chamber which contains a dose of mercury and a pair of electrodes with their tips spaced apart from one another to define an arc gap. An operating system for the lamp includes means for acting on the electrodes to prevent a mercury dose globule from forming between the electrode tips on shutdown of the lamp. The means for acting on the electrodes may comprise means (42, 46) for smoothly reducing the lamp voltage upon lamp shutdown; or means (42, 44, 46) for briefly re-igniting the arc one or more times following shutdown; or means for vibrating the lamp after shutdown.

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