Abstract: A double-ended ceramic metal halide lamp includes a luminous tube; at least two illuminators serially connected with each other deposed inside the luminous tube; and at least one ring-shaped retainers arranged between two illuminators to support the illuminators located along a central line of the luminous tube. A manufacturing method for a ceramic metal halide lamp includes following steps: (1) Arrange at least two serially connected illuminators inside an interior of a luminous tube; (2) Seal two ends of the luminous tube by a press sealing technique; and (3) Extract out the gas inside the luminous tube to form an eyelet at a central portion of the luminous tube.

Abstract: Embodiments of the present invention generally relate to simplified, high voltage, tungsten halogen lamps for use as source of heat radiation in a rapid thermal processing (RTP) chamber or other lamp heated thermal processing chambers. Embodiments include a lamp design that includes an external fuse while reducing the number of part and expense of prior art lamps. In addition, embodiments of the lamps described herein provide sufficient rigidity to handle compressive forces of inserting the lamps into a heating assembly base, while maintaining a simplified fuse design.

Abstract: A double-ended ceramic metal halide lamp includes a luminous tube; at least two illuminators serially connected with each other deposed inside the luminous tube; and at least one ring-shaped retainers arranged between two illuminators to support the illuminators located along a central line of the luminous tube. A manufacturing method for a ceramic metal halide lamp includes following steps: (1) Arrange at least two serially connected illuminators inside an interior of a luminous tube; (2) Seal two ends of the luminous tube by a press sealing technique; and (3) Extract out the gas inside the luminous tube to form an eyelet at a central portion of the luminous tube.

Abstract: A connection piece for connecting graphite electrodes contains at least one region made of graphite and at least one region made of carbon-fiber-reinforced carbon. The graphite contains less than 10 mass-% of fibers and the carbon-fiber-reinforced carbon contains more than 20 mass-% of carbon fibers. The connection piece preferably contains a graphite body in the shape of a cylinder or a bi-cone. There is a plurality of groove-shaped recesses in the graphite body which are filled with the material made of carbon-fiber-reinforced carbon having a percent by weight of carbon fibers of more than 20 mass-%.

Abstract: A mercury-free low-pressure lamp having a bulb is provided. The bulb includes an emissive material and one or more phosphors. The emissive material includes at least one of an alkali metal or an alkaline earth metal, wherein when the bulb is in a non-operational state, the emissive material condenses into a liquid or solid, and when the bulb is in an operational state the emissive material forms an emitter, the emitter in combination with one or more gases generate photons when excited by an electrical discharge. The one or more phosphors are configured to convert at least a portion of the photons to other visible wavelengths.

Abstract: A lamp electrode module includes a lamp cap, a spring electrode, a bottom electrode and a first insulation member. The lamp electrode has an inner sidewall surrounded by an internal thread and an inner bottom surface adjacent to the inner sidewall. The spring electrode has a helix portion wedged in the internal thread and a first connecting portion extended from the helix portion and located inside the lamp cap. The bottom electrode includes a contacting portion abutting against an outer surface opposite to the inner surface and a second connecting portion passing through the lamp cap and erecting on the inner bottom surface. The first insulation member covers the helix portion of the spring electrode and the inner sidewall of the lamp cap.

Abstract: A bushing for a high-pressure discharge lamp, which is suitable for connecting an electrode in the interior of a ceramic discharge vessel to a supply lead in a gastight manner on the exterior of the discharge vessel, wherein the bushing is an electrically conductive ceramic composite consisting of a mixture of LaB6 and at least one second material from the group Al2O3, Dy2Al5O12, AlN, AlON and Dy2O3 is disclosed.

Abstract: An OLED device having rear electrodes. The device comprises a substrate whereon a light emitting region is provided, an anode layer wherein an anode terminal is formed on one side of the top of the light emitting region, an organic layer laminated onto the light emitting region of the anode layer, a cathode layer wherein a cathode terminal is formed on one side of the top of the light emitting region, a protective film which seals the light emitting region, a rear electrode for anode of which one side is connected to the anode terminal and the other side is formed from the upper surface of the cathode layer whereon the protective film is provided, and a rear electrode for cathode of which one side is connected to the cathode terminal and the other side formed from the upper surface of the cathode layer whereon the protective film is provided.

Abstract: In various embodiments, a discharge lamp may include a lamp vessel that includes a discharge vessel enclosing a discharge medium and two lamp shafts each extending coaxially at opposite ends of the discharge vessel, two outer power-feed sections each extending to the outside from one of the lamp shafts, two electrodes each consisting of an electrode rod and electrode head, with the electrode rods being arranged along the lamp shafts such that the two electrode heads are located mutually opposite inside the discharge vessel, a sealed section in each of the two lamp shafts by which a gas-tight electricity passage is formed between the two outer power-feed sections on the one hand and the two electrodes on the other, a narrow section in each of the two lamp shafts that is arranged between the respective sealed section and the electrode head of the associated electrode, with the narrow section closely surrounding the electrode rod, and a damping/guiding element arranged between the narrow section of a lamp shaft

Abstract: The present invention discloses a peripheral line scheme of a display device. The routing of the peripheral lines is designed with a grating configuration to electrically connect to a driver IC or an integrated circuit. When the repair line is employed, a part of the peripheral lines could be separated by a laser optionally, and it subsequently could be welded to the repair line by the laser to improve the ability of the repair line. The display device of the present invention includes a display panel with a plurality of signal lines including the data lines and the scan lines. At least one integrated circuit is electrically connected to the plurality of signal lines to drive the display panel for displaying, and at least one repair line is electrically connected to the integrated circuit. At least one peripheral line is electrically connected to the integrated circuit in the grating configuration and in parallel to the repair lines.

Abstract: A fluorescent display device includes an aluminum wiring layer formed on an insulating substrate; an insulating layer formed on the aluminum wiring layer, the insulating layer being provided with a through-hole disposed on the aluminum wiring layer; a conductive layer filled in the through-hole. The fluorescent display device further includes an anode conductor formed on the insulating layer to cover the conductive layer and a phosphor layer formed on the anode conductor. The conductive layer is formed of solid mixture containing aluminum and graphite.

Abstract: A foil connector (28, 30) suited for use in a lamp (10) is provided. The foil connector includes a substrate layer (40) formed from an electrically conductive material. A coating (42) is provided for reducing oxidation of the substrate during lamp operation. The coating includes a first coating layer (44) on the substrate comprising a noble metal, a second coating layer (46) spaced from the substrate by the first coating layer, the second coating layer comprising a noble metal, and optionally, a third coating layer (48) spaced from the substrate by the first and second coating layers, the third coating layer comprising a noble metal.

Abstract: A high-pressure discharge lamp includes a quartz glass discharge chamber (1) having at least one end (11) provided with a molybdenum film sealing element (2) and at least one electrode (4) which is connected to the sealing element (2) and is protruded in the lower chamber (10) of the discharge chamber (1), wherein the lamp includes a spiral (5) whose slope is equal to or greater than 600% and which encompasses the part of the electrode (4) in the end (11) area provided with the sealing element (2) of the discharge chamber (1) outside of the sealing element (2).

Abstract: An arc tube is provided for use in a high intensity discharge lamp. The arc tube is generally comprised of an elongated outer envelope defining two opposed ends and a cavity therebetween; an electrode sleeve protruding outwardly from each end of the outer envelope, such that each electrode sleeve has a passageway; and an electrical feedthrough member inserted into the passageway of the electrode sleeve, where the feedthrough member includes an inner rod that extends into the cavity of the arc tube and a ceramic sleeve encircling a portion of the inner rod disposed within the passageway. A sealing compound is disposed at an outwardly facing end of the passageway for sealing the feedthrough member to the electrode sleeve, such that the sealing compound extends into the passageway of the electrode sleeve but is spatially separated from the ceramic sleeve.

Abstract: An electron emission device includes a substrate, an anode electrode formed on the substrate, phosphor layers formed on the anode electrode, and resistance layers formed on the substrate and electrically connected to the anode electrode.

Abstract: The bulb (1) of the lamp which defines a longitudinal axis (A) is closed at one end by a seal (3), contact elements being fitted to the one end which are each electrically conductively connected to a power supply line (2) leading to a luminous element, the contact element being accommodated in a tubular part (15) of the seal part, characterized in that the contact element (5) protrudes outwards and is equipped in the interior of the tubular part with at least two outwardly protruding centering parts (10, 11) which are in contact with the tubular extension (16).

Abstract: A light emitting display panel which is provided with a sandwiched portion that is sandwiched between a connection end portion of an electrode and an electrode extension. The sandwiched portion is formed of at least one layer of a light emission functioning layer stack.

Abstract: A mercury-free arc tube for a discharge lamp has a closed chamber filled with rare gas and a metal halide containing at least Na halide or Sc halide and electrodes disposed on both end portions of the closed chamber so as to be opposed to each other, wherein the electrode rod is stepped shape which satisfies relationship of 1.1<A1/A2<7.3, whereas A1 is a cross sectional area of the electrode in a top-end side area protruded into the closed chamber and A2 is a cross sectional area of the electrode in a base-end side area fixed to the end portion of the closed chamber.

Abstract: A high pressure discharge lamp with a trigger wire wound around a side tube portion has the structure in which the side tube portion has a first glass portion extending from a luminous bulb and a second glass portion provided in at least a portion of the inside of the first glass portion, and in which the second glass portion contains at least one substance of Li, Na, and K of from 0.001 wt % to 1.0 wt % inclusive. This structure provides a high pressure discharge lamp operable with a drastically reduced starting voltage.

Abstract: The electrode system for a metal halide lamp with ceramic discharge vessel (4) comprises an electrically conductive leadthrough (9, 10) and an electrode connected thereto, the leadthrough having a fusible region with respect to the electrode, in which that end of the electrode which faces the leadthrough is embedded, at least the fusible region containing one of the high-melting metals Mo or W, and the electrode having a shank made from tungsten. In the regions surrounded by the material of the leadthrough, the electrode has a positively locking means which at least comprises a recess in the shank of the electrode.

Abstract: An electric discharge lamp comprising: a light-transmissive ceramic lamp vessel (1); a first and a second current conductor (2,3) entering the lamp vessel (1), and each supporting an electrode (4,5) in the lamp vessel (1); an ionizable filling comprising a rare gas and a metal halide in the lamp vessel (1); at least the first current conductor (2) within the lamp vessel (1) being halide-resistant, characterized in that the first current conductor (2) at least substantially comprises a material with an at least substantially isotropic coefficient of thermal expansion, said material preferably being chosen from the group of pentamolybdenum boride disilicide, pentamolybdenum diboride silicide, or a combination of these two materials.

Abstract: Sealing foil for making a lamp (1), comprising a metallic base body made from molybdenum and a coating which has been applied to at least part of the base body and which contains chromium, rhenium or ruthenium, alone or as an alloy, the foil being formed as a stack comprising two parts (10, 11) which have a different coating.

Abstract: A discharge lamp of the present invention, which has an starting property, an arc stability and a service life which are improved even if the lamp produces a short arc. The discharge lamp includes a light emitting bulb, sealing members disposed on both sides of the light emitting bulb, metal foils sealed in the sealing members, a pair of electrodes which are connected to the metal foils and have large-diameter portions formed on tips, coils disposed at the rear of the large-diameter portions of the electrodes, external conductors, and a discharge medium enclosed in the light emitting bulb.

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 surfaces 26Aa and 26Ba of tungsten electrodes 26A and 26B pinch-sealed to pinch seal portions 20b1 and 20b2 on the two sides of a light-emission tube 20a of an arc-tube body 20 is set to be 3 ?m or smaller. Thus, the state of pinch-sealing of the tungsten electrodes 26A and 26B to the pinch seal portions 20b1 and 20b2 is 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 portions 20b1 and 20b2 and the tungsten electrodes 26A and 26B as distinct from the conventional structure. In a case where a crack of the arc-tube body 20 is formed owing to the residual compressive stress, the crack is limited to a local portion which is the region adjacent to the joint surface.

Abstract: The reliability of the airtight sealed section is improved by providing a metallic or ceramic insertion member at a portion positioned between an electricity introducing member and a narrow tube in the airtight sealed section. The difference between the inner diameter of the narrow tube and the outer diameter of the insertion member is made 0.02 to 0.6 mm. The electricity introducing member is constructed by a halogen-resistant first member and a second member whose coefficient of linear expansion is similar to that of the narrow tube, and the junction of the first member and second member is covered with a halogen-resistant glass sealant. The difference between the insertion length of the second member into the narrow tube and the flow-in length of the glass sealant into the narrow tube is made 1 mm or more.

Abstract: A discharge chamber for an arc discharge metal halide lamp having light permeable walls bounding a discharge region in which ionizable materials are provided with at least one electrode accommodation opening therein extending along a selected path between that discharge region and a region outside those walls. An electrode arrangement extends through the electrode accommodation opening having therein a thin electrical conductor positioned at least in part therein with a major surface that has surface curvature in at least some of those portions thereof positioned in said electrode accommodation opening to be in one of many alternative configurations. A sealing frit of mixed metal oxides is positioned about at least a portion of the thin electrical conductor within the electrode accommodation opening both at the major surface thereof and on an opposite side thereof.

Abstract: An arc discharge metal halide lamp having a discharge chamber with visible light permeable walls bounding a discharge region through which walls a pair of electrode assemblies are supported with interior ends thereof positioned in the discharge region spaced apart from one another. These electrode assemblies each also extend through a corresponding capillary tube affixed to the walls to have exterior ends thereof positioned outside the arc discharge chamber. At least one of these electrode assemblies comprises an electrode discharge structure with a discharge region shaft extending into the capillary tube corresponding thereto. A helical coil positioned in part about the discharge region shaft extends outwardly in that corresponding capillary tube to be in direct contact with an interconnection shaft extending outside of that corresponding capillary tube to provide an exterior end of this electrode assembly.

Abstract: A discharge lamp includes a luminous bulb in which a luminous material is enclosed and a pair of electrodes are opposed to each other in the luminous bulb; and a pair of sealing portions for sealing a pair of metal foils electrically connected to the pair of electrodes, respectively. The pair of metal foils have a pair of external leads on the side opposite to the side electrically connected to the pair of electrodes, respectively. At least one of the pair of external leads is joined to a lead wire for external connection that is to be electrically connected to an external circuit by the plastic flow of a caulking member.

Abstract: In a foil sealed lamp, a lamp container made of transparent material, has at least one sealing portion made of molybdenum wherein a metallic foil is buried, a light emitting section which is connected to one end of the metallic foil and a lead rod extending outward and connected to other end of the metallic foil, and wherein, in the sealing portion, a gap formed around a circumference portion of the lead rod is filled with sealing agent made of rubidium oxide or cesium oxide, and glass having boron oxide and bismuth oxide as principal components is coated on an outer end surface of the sealing portion so as to close the gap.

Abstract: A fluorescent lamp having a stem provided with first and second lead wires for energization of an electrode and an electrically-insulating member provided therein with a first hole and a second hole larger in cross-sectional area than said second lead wire. The first and second lead wires are inserted in the first and second holes of the electrically-insulating member, respectively, and an outer diameter of a glass envelope of the fluorescent lamp is not smaller than 13 mm and not larger than 29 mm.

Abstract: An efficient and safe lamp with a tungsten halogen capsule may be formed by using a two stage pyrophoric fuse as part of the electrical path to the capsule. The thin walled lamp with tungsten halogen capsule and two stage pyrophoric fuse yields a more efficient, less expensive and yet still safe tungsten halogen lamp. The thin walled lamp with tungsten halogen capsule and pyrophoric fuse provides a safe, thin walled outer envelope tungsten halogen lamp, provide a lamp with an oxygen sensitive fuse operable in low wattage lamps, provides a method manufacturing a pyrophoric fuse sensitive to moderate temperatures, provides an inexpensive and practical, low wattage, thin walled tungsten halogen lamp with a pyrophoric fuse.

Abstract: A super-high pressure discharge lamp of the short arc type which has an arc tube portion in which there is a pair of opposed electrodes and which is filled with at least 0.15 mg/mm3 mercury, and side tube portions which extend from opposite sides of the arc tube portion and in which there are metal foils. The electrodes are each electrically connected to a respective one of the metal foils by a metallic component with cross-sectional area that is smaller than the cross sectional area of the electrodes in the area in which the electrodes are located in the side tube portions.

Abstract: The present invention is a short arc type ultra-high pressure discharge lamp in which a pair of electrodes 3 are disposed inside an arc tube 1 that comprises quartz glass, seal portions 2 are formed that comprise quartz glass and extend to both sides of the arc tube 1, and at least 0.15 mg/mm3 of mercury is filled into the arc tube 1, wherein a metal foil 4 is embedded in each of the seal portions 2, and metal granular lumps 6 are protrusively provided on surfaces of each metal foil 4.

Abstract: The present invention relates to a method for marking quartz glass lamps having at least one fusible metal foil 10, 12, which is surrounded by quartz glass, for supplying electric voltage to luminous means 15 arranged in the interior chamber of a lamp vessel, in which method the fusible metal foil 10, 12 is marked through the quartz glass by means of a laser. The invention also relates to a quartz glass lamp having at least one fusible metal foil 10, 12 which is surrounded by quartz glass, for supplying electric voltage to luminous means 15 arranged in the interior chamber of a lamp vessel, in which lamp the fusible metal foil 10, 12 forms a marking area 16, the marking of the marking area 16 taking place through the quartz glass by means of a laser.

Abstract: A sealed-in foil lamp comprising a metal base member of molybdenum and a coating applied on at least a portion thereof, the coating containing ruthenium alone or a ruthenium alloy.

Abstract: A discharge lamp having a pair of electrodes (2) within a light-emitting tube (30) with air-tight seals (31) formed covering a metallic foil (1) is bonded to each electrode (2). To stiffen the metallic foil, it is provided with a length-wise crease (M).

Abstract: The high-pressure discharge lamp comprises a sealed lamp vessel (1) having a quartz glass wall (2) enclosing a discharge space (3). Metal foils (4) are embedded in the wall, connected to electrode rods (6a) projecting from the wall into the discharge space. The electrode rods (6a) have a first part (7a) and a second part (7b). The second part is made of tungsten with a diameter of 120 to 180 &mgr;m or molybdenum with a diameter of 120 to 350 &mgr;m, or tungsten-molybdenum mixtures with a diameter of 120 to 350 &mgr;m. The second part, which is positioned within the wall (2), prevents premature failure of the lamp caused by leakage.

Abstract: An improvement to the current-carrying components of a lamp includes two filaments connected to two different electrodes and one common electrode, and a switch for directing current through the secondary filament upon the failure of the primary filament. Normally, the current flows through the primary filament. The switch in one embodiment is a wire that does not conduct when the primary filament is operational but conducts on the failure of the primary filament to shunt the current to the secondary filament. The wire is an oxide metal wrapped around two of the three electrodes inside the glass envelop of the lamp. When the primary filament fails, the open circuit voltage breaks across the oxide layer to weld the wire to the electrodes and bypass the primary filament.

Abstract: A discharge lamp of the present invention, which has an starting property, an arc stability and a service life which are improved even if the lamp produces a short arc. The discharge lamp includes a light emitting bulb, sealing members disposed on both sides of the light emitting bulb, metal foils sealed in the sealing members, a pair of electrodes which are connected to the metal foils and have large-diameter portions formed on tips, coils disposed at the rear of the large-diameter portions of the electrodes, external conductors, and a discharge medium enclosed in the light emitting bulb.

Abstract: An efficient and safe lamp with a tungsten halogen capsule may be formed by using a two stage pyrophoric fuse as part of the electrical path to the capsule. The thin walled lamp with tungsten halogen capsule and two stage pyrophoric fuse yields a more efficient, less expensive and yet still safe tungsten halogen lamp. The thin walled lamp with tungsten halogen capsule and pyrophoric fuse provides a safe, thin walled outer envelope tungsten halogen lamp, provide a lamp with an oxygen sensitive fuse operable in low wattage lamps, provides a method manufacturing a pyrophoric fuse sensitive to moderate temperatures, provides an inexpensive and practical, low wattage, thin walled tungsten halogen lamp with a pyrophoric fuse.

Abstract: The high-pressure discharge lamp comprises a sealed lamp vessel (1) having a quartz glass wall (2) enclosing a discharge space (3). Metal foils (4) are embedded in the wall, connected to electrode rods (6) projecting from the wall into the discharge space. The electrode rods (6) have a first part (7a) and a second part (7b) with a diameter of between 250 and 350 &mgr;m and at least an envelope (7c) made of rhenium. The second part, which is positioned within the wall (2), prevents premature failure of the lamp caused by leakage.

Abstract: An arc tube provided with a central sealed chamber 12, in which light-emitting substances are enclosed, having a pair of electrode assemblies disposed opposite to each other. The electrode assemblies are sealed in pinch seal portions 13. The arc tube incorporates a residual-compressive-stress layer 16 formed on a surface of the glass layer 15 in each of the pinch seal portions 13 that contacts the electrode rod 6 included in each electrode assembly. The residual-compressive-stress layer has a length greater than or equal to 30% of the axial length of a glass layer region that only contacts the electrode rod 6 and/or an angular range greater than or equal to 180° in a circumferential direction of the electrode rod. Thermal stress (tensile stress) produced in the boundary between the glass layer 15 and the electrode rods 6 after the arc tube 10 has been turned on is absorbed and dispersed by the residual-compressive-stress layer 16 surrounding the electrode rods 6.

Abstract: The invention relates to an electrode for discharge lamps, comprising a pin which is at least partially surrounded by a solid body. Said solid body consists of a material with a high melting point. The cooling body is therefore easy to mount on the pin and can be solidly connected to the same so that they form a robust unit.

Abstract: A discharge lamp having a discharge vessel through whose wall at least one current feedthrough is guided. A discharge electrode is arranged on one end of the current feedthrough. The current feedthrough is made of at least two separate parts and at least one part is made of niobium, tantalum or alloys based on niobium and/or tantalum. The second part is made of material which is more resistant to oxidation than the first part.

Abstract: An electricity introducing member for a tube lamp includes a closing member and an electrode upholding part formed integrally together; the closing member includes a plurality of layers each comprising a conductive component and silica, the volumetric proportion of the silica being n1, n2, n3, . . . , nx such that n1>n2>n3> . . . >nx, are successively laminated in the form of a cylinder, so that the closing member serves as a functional gradient material; where the diameter of the closing member is D in mm and the total thickness of the laminate of the layers each containing more than 80 volume % of silica is L in mm; L/D is not less than 2: the electrode upholding part is shrink-fitted from the surface on the side of the layer n1 up to the layer containing at most 80 volume % of silica in the closing member. Preferably, where the diameter of the electrode upholding part is d in mm, the ratio of d/D is from 0.12 to 0.6.

Abstract: The electric lamp comprises a lamp vessel (1) and an electric element (4). The electric element is electrically connected to the exterior via a current feed-through comprising an external current conductor (7). By covering the external current conductor with a protective coating (8) contains chromium which can react with SiO2 to form low-melting phases, the lifetime of the lamp is increased significantly.

Abstract: A structure to reduce the likelihood of flashover in a parallel plate electron beam array is disclosed. The structure may comprise a spacer structure between the parallel plates along the outer perimeter of the plates. The spacer structure may include a conductive member. The conductive member may shunt anode to cathode flashovers to a sink outside of the array before they reach the cathode. The conductive member may be provided by a conductive frit made of a metal/glass mixture, a metal foil, or a metal coating that extends through or next to the spacer structure.

Abstract: The discharge vessel has two ends (6), which are closed off by ceramic pl which each contain an elongate capillary tube (12), an electrically conductive lead-through (9, 10) comprising two parts (13, 14) being guided in a vacuum-tight manner through this plug capillary tube (12). The inner part (14) is a pin made of a halide-resistant metal (tungsten), the diameter of which is at most 0.4 mm and which is surrounded by a tubular casing (20, 21) made of ceramic material which consists of a concentric aluminum oxide tube (sleeve), the outer part (13), over its entire length, and the inner part (14), at least over a length of 1 mm from the beginning of the sleeve (20, 21), being sealed off by means of soldering glass (18).

Abstract: Inserted into the cap of a high-pressure discharge lamp is a ceramic fleece hich prevents capping cement (17) from passing into the capillary (18) between the supply lead (9a) and pinch (5).

Abstract: A metal halide headlamp comprising an electrode and a coil wrapping around said electrode to prevent the occurrence of cracks in a sealing portion, in which the diameter d.sub.0 of said electrode, the cross-section S of said electrode including said coil, the inner diameter ID of said coil, the pitch P of said coil, the distance L between an end of said coil and a metal foil, and the amount of metal halides with a NaI-to-ScI.sub.3 ratio are specifically limited. Thereby, the prior art problems, i.e., changes in the lamp characteristics, the degradation of durability, and so on, can be solved.