Abstract: Provided is a light source unit in which mounted light-emitting elements are cooled more homogeneously. The light source unit includes: a substrate having a first main surface on which a plurality of light-emitting diodes (LEDs) are mounted; a first through hole that communicates between the first main surface and a second main surface on a side opposite to the first main surface, the first through hole having a center located within a predetermined range from the center of gravity of the first main surface when viewed in a direction orthogonal to the first main surface of the substrate; a heatsink provided on the side of the second main surface of the substrate; and a first fixing screw that is inserted through the first through hole of the substrate and screwed into a screw hole, provided corresponding to the first through hole, to fix the substrate and the heatsink.

Abstract: Provided is a light source unit in which mounted light-emitting elements are cooled more homogeneously. The light source unit includes: a substrate having a first main surface on which a plurality of light-emitting diodes (LEDs) are mounted; a first through hole that communicates between the first main surface and a second main surface on a side opposite to the first main surface, the first through hole having a center located within a predetermined range from the center of gravity of the first main surface when viewed in a direction orthogonal to the first main surface of the substrate; a heatsink provided on the side of the second main surface of the substrate; and a first fixing screw that is inserted through the first through hole of the substrate and screwed into a screw hole, provided corresponding to the first through hole, to fix the substrate and the heatsink.

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).