US 7,569,993 B2
Gas discharge tube with discharge path limiting means
Yoshinobu Ito, Hamamatsu (Japan); Koji Matsushita, Hamamatsu (Japan); and Masaki Ito, Hamamatsu (Japan)
Assigned to Hamamatsu Photonics K.K., Hamamatsu-shi, Shizuoka (Japan)
Appl. No. 10/512,887
PCT Filed Apr. 30, 2003, PCT No. PCT/JP03/05551
§ 371(c)(1), (2), (4) Date Jun. 10, 2005,
PCT Pub. No. WO03/094199, PCT Pub. Date Nov. 13, 2003.
Claims priority of application No. 2002-128768 (JP), filed on Apr. 30, 2002.
Prior Publication US 2005/0231119 A1, Oct. 20, 2005
Int. Cl. H01J 17/02 (2006.01); H01J 61/02 (2006.01)
U.S. Cl. 313—611  [313/609; 313/610; 313/612] 37 Claims
OG exemplary drawing
 
1. A gas discharge tube wherein a gas is enclosed in a sealed envelope, and a light is emitted outward from a light emitting window of the sealed envelope by producing a discharge between an anode portion and cathode portion both disposed in the sealed envelope, comprising:
a first discharge path limit portion, arranged in a midway of a discharge path between the anode portion and the cathode portion, and provided with a first opening for narrowing the discharge path, the first opening having an entrance area and an exit area;
a second discharge path limit portion, arranged in a midway of the discharge path between the first discharge path limit portion and the anode portion, and provided with a second opening having a straight section for narrowing the discharge path a diameter of which is constant and which extends in a direction of an optical axis, and a spread section a diameter of which increases in size from an end of the straight section on the side of the cathode portion toward the first opening and which extends in the direction of the optical axis, the diameter of the exit area of the first opening being larger than the diameter of the straight section of the second opening.