Abstract: A high-pressure discharge lamp includes a cathode body composed of a cathode made of tungsten or tungsten alloy and a lead rod inserted in a lead rod insertion hole of the cathode. The cathode has a carbonized layer made of tungsten carbide (W2C) formed on a surface thereof exposed to a discharge space (except for a tip portion thereof) and on an inner surface of the lead rod insertion hole. The carbonized layer contains carbon in an amount of 0.44 g/cc to 0.53 g/cc.

Abstract: A high-pressure discharge lamp includes a cathode body composed of a cathode made of tungsten or tungsten alloy and a lead rod inserted in a lead rod insertion hole of the cathode. The cathode has a carbonized layer made of tungsten carbide (W2C) formed on a surface thereof exposed to a discharge space (except for a tip portion thereof) and on an inner surface of the lead rod insertion hole. The carbonized layer contains carbon in an amount of 0.44 g/cc to 0.53 g/cc.

Abstract: A discharge lamp includes an emitter other than thorium, which is added to a cathode in a luminous tube. Early depletion of the emitter due to excessive vaporization of the emitter from the cathode is prevented, while achieving stable lighting even at the start-up of the lighting. A main body part (31) of the cathode (3) is made from a high-melting-point metal material that contains no thorium, and a front end part (32) thereof is made from a high-melting-point metal material that contains an emitter (other than thorium). A sintered compact (34), which contains an emitter (other than thorium) at a concentration higher than the emitter contained in the front end part (32), is buried in a sealed space (33) that is formed within the main body part (31) and/or the front end part (32). The sintered compact (34) abuts against the front end part (32).

Abstract: A discharge lamp includes a cathode in a luminous tube, and an emitter, other than thorium, is added to the cathode. The emitter is prevented from being excessively vaporized from the cathode and depleted soon. Smooth lighting is enabled even at start-up. A main body part (31) of the cathode (3) is made from a metallic material having a high melting point and containing no thorium. A front end (32) is made from a metallic material having a high melting point and containing an emitter (excepting thorium). Inside a sealed space (33) formed in the main body part (31) and/or the front end part (32) is received a sintered compact (34) containing an emitter (excepting thorium) that is higher in concentration than the emitter contained in the front end part (32).

Abstract: A discharge lamp includes an emitter other than thorium, which is added to a cathode in a luminous tube. Early depletion of the emitter due to excessive vaporization of the emitter from the cathode is prevented, while achieving stable lighting even at the start-up of the lighting. A main body part (31) of the cathode (3) is made from a high-melting-point metal material that contains no thorium, and a front end part (32) thereof is made from a high-melting-point metal material that contains an emitter (other than thorium). A sintered compact (34), which contains an emitter (other than thorium) at a concentration higher than the emitter contained in the front end part (32), is buried in a sealed space (33) that is formed within the main body part (31) and/or the front end part (32). The sintered compact (34) abuts against the front end part (32).

Abstract: A discharge lamp includes a cathode in a luminous tube, and an emitter, other than thorium, is added to the cathode. The emitter is prevented from being excessively vaporized from the cathode and depleted soon. Smooth lighting is enabled even at start-up. A main body part (31) of the cathode (3) is made from a metallic material having a high melting point and containing no thorium. A front end (32) is made from a metallic material having a high melting point and containing an emitter (excepting thorium). Inside a sealed space (33) formed in the main body part (31) and/or the front end part (32) is received a sintered compact (34) containing an emitter (excepting thorium) that is higher in concentration than the emitter contained in the front end part (32).

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode comprises a main part made from tungsten and a tip end part made from thoriated tungsten, wherein thorium oxide particles having been peripherally coated with thorium are contained in the tip end part of said cathode.

Abstract: A short arc type discharge lamp includes a cathode and an anode arranged inside an arc tube to face each other. The cathode comprises a main body portion made of tungsten and an emitter portion made of thoriated tungsten that is joined at the tip of the main body portion, where a metal oxide other than thorium (Th) is contained in the main body portion of the cathode, and a tungsten carbide layer is formed on the metal oxide.

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode consists of a main body part with tungsten as the main constituent and an emitter part comprised of thoriated tungsten, wherein an oxygen content of the main body part of said cathode is lower than that of the emitter part, and band-shaped tungsten carbide is formed at the tip end face of the emitter part of said cathode.

Abstract: A discharge lamp with excellent arc stability and excellent durability in which the use level of thoriated tungsten is restrained has an anode and a cathode in the interior of a discharge vessel, wherein said cathode is made up from a thoriated tungsten part with a tungsten filling ratio of at least 90 vol.-% and a main body part connected to said thoriated tungsten part and consisting of pure tungsten, wherein a ratio ST/S of a side surface area ST of said thoriated tungsten part and a side surface area S of said cathode is in a range of from 0.005 to 0.15, with the proviso that, in case the cathode has a length in the direction of the cathode axis which exceeds twice the maximum diameter of the cathode, a side surface area S is used for calculating the ratio ST/S which corresponds to the side surface area where the distance along the cathode axis from a tip end adjacent to the anode is twice the maximum diameter of the cathode.

Abstract: A high pressure discharge lamp light source device is provided having a quartz glass discharge vessel enclosing two opposed electrodes that are spaced apart by at most 2.0 mm, each electrode having a projection formed at a tip end thereof, at least 0.20 mg/mm3 of mercury and a halogen; and a power supply device for supplying alternating current to the lamp, The power supply device is adapted to switch between a nominal electric power lighting mode and a low electric power lighting mode having a defined current value in a range of 40 to 70% of a nominal electric power consumption. In the low power mode, the power supply alternately supplies a base current in a range between 100 Hz and 5 kHz a boost current having a higher current value than that of the base current.

Abstract: A xenon short arc lamp for a digital projector, includes an anode, a cathode having a cathode main body that is made of tungsten containing electron emissive material, and an arc tube made of silica glass, wherein a supply source of carbon is formed on a metal portion in the arc tube except a tip area of the cathode, and the carbon is supplied to the tip of the cathode through a gaseous phase during lamp lighting, so that a surface layer of the cathode is melt.

Abstract: A short arc type discharge lamp includes a cathode and an anode arranged inside an arc tube to face each other. The cathode comprises a main body portion made of tungsten and an emitter portion made of thoriated tungsten that is joined at the tip of the main body portion, where a metal oxide other than thorium (Th) is contained in the main body portion of the cathode, and a tungsten carbide layer is formed on the metal oxide.

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode consists of a main body part with tungsten as the main constituent and an emitter part comprised of thoriated tungsten, wherein an oxygen content of the main body part of said cathode is lower than that of the emitter part, and band-shaped tungsten carbide is formed at the tip end face of the emitter part of said cathode.

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode comprises a main part made from tungsten and a tip end part made from thoriated tungsten, wherein thorium oxide particles having been peripherally coated with thorium are contained in the tip end part of said cathode.

Abstract: A short arc type discharge lamp wherein a cathode and an anode are arranged opposite to each other in an interior of a light emitting tube and said cathode comprises a main part made from tungsten and an emitter part made from thoriated tungsten, and said emitter part having been diffusion bonded to the main part via a joint face, wherein gaps are formed locally at said joint face of said main part and the emitter part.

Abstract: A discharge lamp with excellent arc stability and excellent durability in which the use level of thoriated tungsten is restrained has an anode and a cathode in the interior of a discharge vessel, wherein said cathode is made up from a thoriated tungsten part with a tungsten filling ratio of at least 90 vol.-% and a main body part connected to said thoriated tungsten part and consisting of pure tungsten, wherein a ratio ST/S of a side surface area ST of said thoriated tungsten part and a side surface area S of said cathode is in a range of from 0.005 to 0.15, with the proviso that, in case the cathode has a length in the direction of the cathode axis which exceeds twice the maximum diameter of the cathode, a side surface area S is used for calculating the ratio ST/S which corresponds to the side surface area where the distance along the cathode axis from a tip end adjacent to the anode is twice the maximum diameter of the cathode.

Abstract: A discharge lamp lighting apparatus includes a discharge container, a pair of electrodes and a power supply apparatus. An alternating current of a frequency, which is lower than stationary frequency, is inserted periodically into the alternating current of stationary frequency. When a lighting current value of the discharge lamp is smaller than a predetermined lower limit, the frequency is set as predetermined minimum frequency. When the lighting current value of a discharge lamp is larger than a predetermined maximum value, the frequency is set as predetermined maximum frequency. When a lighting current value of the discharge lamp is between the lower limit and the maximum value, the frequency is set as a selected frequency corresponding to the lighting current value. The selected frequency increases according to an increase of frequency change as a lighting current value increases.

Abstract: A xenon short arc lamp for a digital projector, includes an anode, a cathode having a cathode main body that is made of tungsten containing electron emissive material, and an arc tube made of silica glass, wherein a supply source of carbon is formed on a metal portion in the arc tube except a tip area of the cathode, and the carbon is supplied to the tip of the cathode through a gaseous phase during lamp lighting, so that a surface layer of the cathode is melt.

Abstract: For maintaining the projections of the electrode tip ends in the ideal condition and maintaining a stable arc even if the lamp is lighted with a lamp power of at most 70% of the rated electric power, a high pressure discharge lamp light source device is provided, comprised of a high pressure discharge lamp having a discharge vessel made from quartz glass and a pair of electrodes arranged oppositely to each other with a spacing of at most 2.0 mm, each electrode having a projection formed at a tip end thereof, and mercury of at least 0.