Electric lamp and discharge devices – With gas or vapor – Having particular electrode structure
Reexamination Certificate
2005-05-10
2005-05-10
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Having particular electrode structure
C313S634000, C313S331000, C313S332000, C313S623000, C313S624000, C313S625000, C445S024000, C445S025000, C445S026000
Reexamination Certificate
active
06891332
ABSTRACT:
An arc tube, which is capable of prolonging the life thereof by preventing occurrence of a leak caused from a crack of an arc-tube body, has the average surface roughness of each of outer surfaces26Aa and26Ba of tungsten electrodes26A and26B pinch-sealed to pinch seal portions20b1and20b2on the two sides of a light-emission tube 20aof an arc-tube body20is set to be 3 μm or smaller. Thus, the state of pinch-sealing of the tungsten electrodes26A and26B to the pinch seal portions20b1and20b2is brought to a state in which the two elements are engaged with small pits and projections. Therefore, great compressive stress is not left in the region adjacent to the joint surface between the pinch seal portions20b1and20b2and the tungsten electrodes26A and26B as distinct from the conventional structure. In a case where a crack of the arc-tube body20is formed owing to the residual compressive stress, the crack is limited to a local portion which is the region adjacent to the joint surface. As a result, the crack is not enlarged to reach the surface of the arc-tube body20.
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Japanese Abstract No. 07226185, dated Aug. 22, 1995.
Japanese Abstract No. 2000100377, dated Apr. 7, 2000.
Irisawa Shinichi
Ohshima Yoshitaka
Koito Manufacturing Co. Ltd.
Patel Nimeshkumar D.
Roy Sikha
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