Patent ID: 7683550
Filing Date: 2010-03-23
Classification: H01J

Abstract:
1. A low-pressure discharge lamp, comprising: a glass tube having an inner diameter in a range of 1 to 5 mm; and a pair of electrodes disposed at end portions in the glass tube, wherein the pair of electrodes contain at least one transition metal selected from transition metals of Groups IV to VI, mercury and a rare gas containing argon, neon and krypton are sealed in an inner portion of the glass tube, and a relationship between a cathode glow discharge density (converted into a current density) J and a composition index a of the sealed rare gas of the low-pressure discharge lamp satisfies the following expression where J represents a numerical value obtained by dividing a current density per a unit effective discharge surface area of an electrode by a square of a sealing pressure P of a rare gas, S represents an effective discharge surface area (mm 2 ) of an electrode, I represents a RMS lamp current (mA), P represents the pressure (kPa) of a sealed rare gas, and αrepresents a composition index of a sealed rare gas that is a constant expressed by α=(90.5A +3.4N +24.3K)×10 −3 when a total of a composition ratio A of argon, a composition ratio N of neon, and a composition ratio K of krypton is expressed by A+N+K=1.