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US 7,443,100 B2Granted
ARC tube discharge lamp with compression strain layer
AssigneeKoito Manufacturing Co., Ltd.
InventorsTakeshi Fukuyo, Michio Takagaki, Akira Homma, Shinichi Irisawa
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Abstract
In a mercury-free arc tube, electrodes are configured by electrode rods heat-treated at 1,200 to 2,200° C. in a vacuum atmosphere, and which have a thickness of 0.3 mm or more. The size (radius R) of a residual compression strain layer formed around the electrode rod is set to be ¼ or less of the width D of the pinch seal portion. A glass layer outside the residual compression strain layer is thickened, thereby enhancing the strength of the pinch seal portion.
Claims8
A mercury-free arc tube for a discharge lamp device, comprising:
- a closed glass bulb disposed in a middle of a glass tube, wherein a starting rare gas and a light emitting substance are enclosed in the closed glass bulb;
- a tungsten electrode rod sealingly attached to a pinch seal portion disposed in an end of the glass tube, wherein a tip end portion of the electrode rod projects in the closed glass bulb;
- and
- a residual compression strain layer formed in a contact face between a glass layer in the pinch seal portion and the electrode rod, wherein the residual compression strain layer surrounds the electrode rod,
- wherein the electrode rod has a diameter of 0.3 mm or more, and
- the residual compression strain layer has a radius R≦D/4 about the electrode rod with respect to a width D of the pinch seal portion, the width D of the pinch seal portion is in a direction that is perpendicular to a longitudinal direction of the arc tube.
3 more elements
Dependencies are inferred from the claim text.