Abstract: This disclosure relates to a low mercury content, metal halide lamp having a ceramic arc tube with an aspect ratio ranging from approximately 1.15 up to about 4.75, and having a fill in the arc tube of up to 2 milligrams of mercury per cubic centimeter and up to 10 milligrams of zinc metal and/or zinc/zinc iodide per cubic centimeter.

Abstract: A mercury light source tube such that a detrimental effect on its lifetime caused by gathering of mercury at peripheral portions of electrodes can be prevented or controlled, a light source device, and a display device. The mercury light source tube has a tube body in which mercury is sealed, electrodes provided to the tube body, and projections provided on an outer surface of the tube body to be integral with the tube body. The projections are placed between the electrodes or in positions at a distance from the electrodes toward the tube body center. The projections locally increase the surface area of the tube body so as to easily radiate heat to the outside, and locally decrease temperatures of the positions where the projections are placed and their peripheral portions so that mercury gathers at the low temperature portions.

Abstract: A metal-halogenide filling for forming an ionisable filling comprises at least one inert gas, mercury and at least one halogen, the filling including at least the components Rb-halogenide and Mn-halogenide. This filling can in particular be contained in the discharge container of a metal-halogenide lamp.

Abstract: A metal halide fill for forming an ionizable fill comprises at least one inert gas, mercury and metal halides, the fill comprising the constituents Hg halide, Na halide, Tl halide and halides of the rare earths. This fill may be contained in particular in the discharge vessel of a metal halide lamp which has an outer bulb.

Abstract: A light source device, including an alternating current high-pressure mercury lamp having a pair of electrodes opposite each other with a spherical light-emitting part having at least 0.15 mg/mm3 of mercury and halogen at 10?6 ?mol/mm3 to 10?2?mol/mm3, and cylindrical hermetically sealed parts extending from both ends of the light-emitting part. External leads protrude from the ends of the light-emitting part for receiving alternating current. A reflecting mirror having a concave reflecting part surrounds the light-emitting part and a cylindrical neck part. An adhesive for securing the mercury lamp and the reflecting mirror fills a periphery of the hermetically sealed parts of the mercury lamp. The distance L2 (mm) from a center in between the electrodes to the adhesive is set at a value of one of 16 mm or less and 20 mm or greater.

Abstract: Carrier element on which an Hg-containing material for application in a discharge lamp is formed, and discharge lamp with such a carrier element The invention relates to a carrier element on which an Hg-containing material for application in a discharge lamp (1) is formed, the Hg-containing material being in the form of a bar-shaped element (12) and being arranged on a holder (14, 15, 16, 17; 19) of the carrier element (11). The invention also relates to a discharge lamp of such a carrier element.

Abstract: A low wattage mercury vapor lamp comprises a discharge vessel (10) including a tubular body (12), first and second electrodes (20, 22) and two end walls (16, 18), which close opposite ends of the tubular body. The discharge vessel contains an ionizable fill material having a concentration of mercury of from 0.10 to 0.20 mg/mm3. The discharge vessel operates at elevated pressures of from 80 to 170 atmospheres at power of 20 watts resulting in improved lumen maintenance and reduced through-life color shift.

Abstract: The invention relates to a lamp, e.g. a UHP-Lamp, comprising a burner (10) with an ionizable filling and an amount of mercury contained therein, having a housing (30, 60; 20, 30) with at least one port (40), whereby the inner opening surface (50) area of the port/s is adapted to reduce the amount of mercury which is able to expose to the outside after an explosion of the burner (10).

Abstract: A low-pressure mercury vapor discharge lamp has a light-transmitting discharge vessel (10) enclosing, in a gastight manner, a discharge space (13) provided with a filling of mercury and a rare gas. The discharge vessel comprises discharge means for maintaining a discharge in the discharge space. The discharge vessel is provided with a luminescent layer (17) comprising a mixture of at least a red and a green luminescent material. The red luminescent material comprises (Y,Gd)2O3:Eu. The green luminescent material comprises (Ba,Ca,Sr)2SiO4:Eu and/or (Sr,Ca,Ba,Mg,Zn)Si2N2O2:Eu. Particles of the green luminescent material are surrounded by a coating of aluminum oxide. Preferably, at least 50% of the particles of the green and red luminescent materials have an average diameter greater than or equal to approximately 5 ?m. The mixture of the red and green luminescent materials render a low-pressure mercury-vapor discharge lamp with an improved lumen equivalent.

Abstract: The invention relates to a lamp, e.g. a UHP-Lamp, comprising a burner with an ionizable filling and an amount of mercury contained therein, having at least one closing means (40, 50) which closes immediately and/or hermetically and/or irreversibly all in- and/or outlets of the lamp to enclose the mercury in the lamp upon detection of an explosion of the burner.

Abstract: Disclosed is a compact self-ballasted fluorescent lamp with higher luminous efficiency than conventional lamps and improved luminous flux rising characteristics at lamp startup equivalent to those of general fluorescent lamps. The compact self-ballasted fluorescent lamp (1) includes an arc tube (2) formed by a bent glass tube (9) covered with a globe (6). The glass tube (9) has a turning part substantially in the middle between its both ends, a first spiral part starting from one end and wound around an axis toward the turning part, and a second spiral part starting from the turning part and wound around the axis toward the other end. The arc tube (2) has mercury enclosed therein in a single form. The glass tube (9) has a substantially circular-shaped cross section and an inner diameter of 7.4 mm. The turning part is connected to the globe (9) via a heat-conductive member (15).

Abstract: A mandrel has a main body having a substantially-cone-shape. The main body has, on its circumferential surface, a spiral-shaped groove at which the glass tube to be wound is held. The groove, in cross section, has a contact range in which the glass tube's circumferential surface is in contact. One end of the contact range corresponds to a circumference part of the glass tube in wound state which is closest to the axis of the main body of the mandrel, a part of the groove that extends from the circumference part towards the apex of the main body is parallel to the axis of the mandrel, and the pitch of the groove in the axial direction of the mandrel is formed smaller than the outer diameter of the glass tube. The glass tube wound on the mandrel is easily removed from the main body by lowering the mandrel. In the arc tube formed in such a way, any two glass tube portions, which are adjacent to each other in the axial direction of the arc tube, overlap with each other.

Abstract: The present invention relates to mercury amalgams in discharge lamps for use at elevated operating temperatures.

Abstract: A UV-emitting, Ce,Pr-coactivated calcium pyrophosphate phosphor is provided wherein the Pr activator increases the phosphor's sensitivity to excitation by 185 nm radiation. The improved sensitivity to the 185 nm radiation allows the phosphor to make better use of the approximate 10% of the UV radiation that is emitted at 185 nm by a low pressure mercury discharge.

Abstract: The invention relates to a high pressure discharge lamp intended for use in assimilation lighting. According to the invention the high-pressure discharge lamp has a discharge vessel, which besides a buffer gas, comprises substantially LiI as metal halide or a mixture of LiI and NaI.

Abstract: he present invention aims at providing a metal halide lamp having a configuration to achieve the following goals: to prevent the lamp from burning out during the life due to a rise in lamp voltage; and to obtain high luminous efficiency at the same time. The metal halide lamp 1 comprises: an arc tube 4 made of translucent ceramic and having a main tube part 6 in which a pair of electrodes 14 is disposed; and an outer tube 3 housing the arc tube 4 therein. 4.0?L/D?10.0, where L (mm) is a length of a space between the electrodes 14 and D (mm) is an internal diameter of the main tube part 6. R/r ?3.4, where R (mm) is an internal diameter of the outer tube 3 and r (mm) is an external diameter in the main tube part 6 of the arc tube 4, within a region positionally corresponding to, in a radial direction of the outer tube and the arc tube, the space between the electrodes 14, on a cross-sectional surface where an outer circumference of the arc tube 4 comes closest to an inner circumference of the outer tube 3. M?4.

Abstract: The metal halide lamp has a ceramic discharge vessel and contains two groups of metal halides: a first group made up of the emitters and a second group made up of the wetters. The second group comprises at least one of the metal halides of Mg or Yb.

Abstract: In the metal halide high-pressure discharge lamp for stage, film and television lighting systems and for projection technology and effect lighting, the discharge vessel contains dysprosium and cesium as fill metals for the metal halides. Optimum results for dimmability, arc instability and color rendering are achieved if the fill additionally includes 0.12 to 3.8 ?mol of vanadium and if appropriate 0.05 to 1.0 ?mol of zirconium per ml of vessel volume. These metals achieve improved color rendering, in particular red rendering, with an Ra of from 70 to 95 and an R9 of from 45 to 90.

Abstract: A high-pressure discharge lamp has a lamp bulb of silica glass encapsulating mercury, an inactive gas, and a mixed halogen gas containing at least two halogen gases, and at least a pair of electrodes disposed in the lamp bulb in confronting relation to each other. The type and content of a primary halogen gas whose content is the greatest in the mixed halogen gas are determined based on a bulb wall load.

Abstract: This invention aims at providing a low-pressure mercury lamp having an improved luminous efficiency while maintaining the compactness and long life of the arc tube. This lamp comprises an arc tube formed by bending a glass tube. This arc tube is formed into a double-spiral structure comprising: a turning part located in substantially the midsection from both ends of the glass tube; a first spiral part starting from one of the ends and spiraling around the pivotal axis to reach the turning part; and a second spiral part starting from the turning part and spiraling around the pivotal axis to the other end. The glass tube has a circular shape in cross section with 7.4 mm inner diameter. This low-pressure mercury lamp is a 12 W lamp alternative to a 60 W incandescent lamp, and the bulb wall loading under steady state illumination is set at 0.103 W/cm2.

Abstract: The invention relates to a high-pressure discharge lamp with a discharge vessel having a filling comprising—a rare gas, for example argon, —mercury, and —chlorine, wherein the filling quantities of mercury [Hg] and chlorine [Cl] comply with the following conditions: —[Hg](E[Cl]3 200 (?mole/cm3)2, —[Cl] £ 10 ?mole/cm3. The condition [Hg](E[Cl]3 200 (?mole/cm3)2 achieves HgCl vapor pressures in the discharge sufficient for generating significant radiation components of the B2S+-X2S+ band system of this molecule. The condition [Cl] £ 10 ?mole/cm3 serves to limit the chemical aggressiveness of the chlorine filling, in particular to limit the attacks on the wall and electrodes and thus to achieve longer lamp lives. The addition of chlorine-binding metals, in particular of germanium, leads to a further improvement in the radiation and life properties of the lamp.

Abstract: An 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, wherein sealing pressure of the rare gas is 0.6 MPa or more, and a sealing density of the Sc halide in the closed chamber is ranging from 1.25 to 4.70 mg/ml. In the arc tube, since the Xe gas sealing pressure slightly higher than 0.6 MPa, the pressure in the closed chamber is increased during its lightening state. Thus, reactions leading to a flicker occurrence may be accelerated. However, the flicker occurrence can be suppressed by setting the Sc halide sealing density to 4.70 mg/ml or less. Further, a luminous efficiency required for the lamp can be assured by setting the Sc halide sealing density to 1.25 mg/ml or more.

Abstract: A metal halide lamp (10) includes a discharge vessel (12) which may be formed of a ceramic material. The vessel defines an interior space (16). An ionizable fill (17) is disposed in the interior space. The ionizable fill includes an inert gas, mercury, and a halide component. The halide component includes an alkali metal halide, an alkaline earth metal halide component, and optionally at least one of a rare earth halide and a Group IIIA halide. The alkaline earth metal halide component includes at least one of a barium halide and a strontium halide. At least one electrode (18, 20) is positioned within the discharge vessel so as to energize the fill when an electric current is applied thereto. The lamp having a wall loading, when energized, which is sufficient to maintain an active tungsten halogen cycle.

Abstract: A metal halide fill for a discharge lamp is provided that is comprised of mercury and a mixture of metal halide salts which includes magnesium iodide as a full or partial replacement for calcium iodide. The replacement of at least some of the calcium iodide improves the behavior of the molten salt condensate in the arc tube. In particular, the mixture of metal halide salts contains about 1 to about 50 mole percent sodium iodide, about 15 to about 50 mole percent of a rare earth iodide, about 10 to about 30 mole percent magnesium iodide, about 10 to about 25 mole percent of indium iodide, and about 0 to about 25 mole percent calcium iodide, wherein the sum of the amounts of calcium iodide and magnesium iodide in the mixture is from about 20 to about 45 mole percent.

Abstract: It is an object of the present invention to provide a high pressure discharge lamp lighting apparatus, has a structure to control decrease of illuminance on a screen which is thought to be a cause of wear of an anode in an early stage of the life span. The high pressure discharge lamp lighting apparatus has a high pressure discharge lamp in which a pair of electrodes is arranged so as to face each other at an interval of 2 mm or less in an arc tube which is made of quartz glass, and mercury of 0.16 mg/mm3 or more, rare gas, and halogen of 1×10?6 to 1×10?2 ?mol/mm3 is enclosed, and a power supply apparatus supplying direct current to the discharge lamp, wherein the power supply apparatus superimposes an alternating component on the direct current and impress the superimposed current to the discharge lamp.

Abstract: A metal halide lamp comprising a substantially cylindrical discharge vessel having an internal diameter Di<2.0 mm and filled with an ionizable filling, wherein two electrodes are present at a mutual distance EA for maintaining a discharge in the discharge vessel, wherein the filling comprises an inert gas, such as Xe, having a pressure at room temperature between 5 and 25 bar, and an ionizable salt, characterized in that said ionizable salt is selected from the group comprising PrI3, NdI3 and LuI3.

Abstract: A short arc type high pressure discharge lamp has a pair of electrodes disposed inside the lamp and facing each other, a light emitting portion encapsulating more than 0.15 mg/mm3 mercury, and sealing portions that extend to both sides of the light emitting portion, seal part of electrodes respectively, and join the electrodes and metallic foil, wherein a cross-sectional view of the metallic foil is an approximately omega shape.

Abstract: A short arc type super high pressure discharge lamp has a pair of electrodes, a light emitting portion in which greater than 0.15 mg/mm3 of mercury is enclosed, and sealing portions provided on both sides of the light emitting portion, wherein at least one of the pair of electrodes has a thick portion which extends into one of the sealing portions and a coil is wound around the thick portion in the one of the sealing portion via a gap.

Abstract: An automotive lamp has a sealed envelope of barium silica glass that is essentially free of cadmium and in which a light emitting element is contained. Lead-in wires extend through the envelope and are coupled to the light emitting element. The glass envelope and lead-in wires have respective coefficients of thermal expansion over a temperature range form ambient to 520° C. which closely match one another to minimize stress and cracking of the envelope at the interface.

Abstract: An arc discharge metal halide lamp having a discharge chamber having visible light permeable walls bounding a discharge region supported electrodes in a discharge region spaced apart by a distance Le with an average interior diameter equal to D so they have a selected ratio. Ionizable materials are provided in this chamber involving a noble gas, one or more halides, and mercury in an amount sufficiently small so as to result in a relatively low maximum voltage drop between the electrodes during lamp operation.

Abstract: A diffuser is formed on an inner surface of a globe included in a compact self-ballasted fluorescent lamp, and a diffuse transmittance of the diffuser ? is set at 95%. When designing dimensions of the compact self-ballasted fluorescent lamp, at the same time, a ratio Dg/Pg is set at 0.8 or greater. Here, Pg is a helical pitch of an arc tube having a helical configuration, and Dg is a half of a difference between a helix diameter of the arc tube and a maximum outside diameter of the globe.

Abstract: A phosphor comprises: (a) at least a first metal selected from the group consisting of yttrium and elements of lanthanide series other than europium; (b) at least a second metal selected from the group consisting of aluminum, gallium, indium, and scandium; (c) boron; and (d) europium. The phosphor is used in light source that comprises a UV radiation source to convert UV radiation to visible light.

Abstract: A phosphor comprises a borate of terbium, at least an alkaline-earth metal, and at least a Group-3 metal. In one embodiment, the phosphor has a formula of A3(D1-xTbx)3(BO3)5; wherein A is at least an alkaline-earth metal selected from the group consisting of calcium, barium, strontium, and magnesium; D is at least a Group-3 metal selected from the group consisting of lanthanum, scandium, and yttrium; and 0<x<0.5. The phosphor can be used in light sources such as those based on mercury discharge or light-emitting diodes and in displays.

Abstract: A fluorescent lamp post-production heating structure allows for even dispersion of mercury and other lamp compounds throughout the entire length of assembled fluorescent lamps by allowing uniform and thorough heating of each lamp's sealed chamber containing these materials to a temperature high enough to vaporize the mercury therein.

Abstract: A metal vapor discharge lamp, comprises: a translucent ceramic envelope, the envelope comprising a center bulb for defining a discharge space and side tubes, the center bulb and the side tubes being integrally molded; a pair of current suppliers extending through hollows of the side tubes respectively, each of the current suppliers comprising an electrode and a lead-in wire, a first end of the electrode being disposed in the discharge space, a second end of the electrode being connected with the lead-in wire; a sealant for hermetically sealing open ends of the side tubes; and a light-emitting metal contained in the discharge space. An inner wall and an external wall of a seamless boundary portion between the center bulb and each of the side tubes have the smallest curvature radius of Ri mm and Ro mm, respectively. The center bulb has an inner diameter of D mm. The lamp has an electric power of P watts. The radius Ri, radius Ro, diameter D and electric power P satisfy, ?0.00076P+0.304?Ri/D??0.00076P+0.

Abstract: A phosphor comprises europium, at least two alkaline-earth metals, and at least a Group-13 metal. In one embodiment, the phosphor has a formula selected from the group consisting of Sr4-a-zAaEuzD12O22 and Sr4-a-zAaEuzD14O25; wherein A is at least an alkaline-earth metal other than strontium; D is an element selected from the group consisting of Group-13 metals, group-3 metals, and rare-earth metals; 0<a<4; 0.001<z<0.3; and 4-a-z>0. The phosphor can be used in light sources and displays.

Abstract: A phosphor comprises a material having a formula of AMgD10O17:Eu2+,Mn2+, wherein A is at least an alkaline-earth metal selected from the group consisting of Ba, Sr, Ca, and combinations thereof; and D is at least a metal selected from the group consisting of Al, Ga, In, and combinations thereof; wherein Eu2+ ions are present in an amount from about 10 to about 50 atom percent of a combined quantity of A ions and europium ions, and Mn2+ ions are present in an amount from about 5 to about 30 atom percent of a combined quantity of magnesium ions and manganese ions. The phosphor is used alone or in conjunction with other phosphors to convert UV/blue radiation emitted by a source, such as an LED or a gas discharge device, to visible light.

Abstract: A phosphor comprises a material having a formula of AB3O6:Ce,Mn, wherein A is at least a rare-earth metal other than cerium. The phosphor can be used in light sources and displays.

Abstract: An arc discharge lamp containing a quantity of elemental mercury at least partially convertible to soluble mercury, provides for including within the lamp a quantity of a non-metallic copper-containing compound and an ingredient X, said ingredient X including a noble metal or a noble metal compound selected from the group consisting of silver and compounds of silver, gold and platinum, and a lamp containing same.

Abstract: A high-pressure mercury lamp is provided that includes a transparent envelope made of quartz glass, in which mercury, halogen, and a rare gas are sealed and a pair of electrodes provided in the transparent envelope. The amount of the halogen sealed in the transparent envelope is in the range from 1.0×10?6 ?mol/mm3 to 1.0×10?2 ?mol/mm3, and 2.5 mol % to 25 mol % of oxygen with respect to the amount of the halogen is present in the transparent envelope. The high-pressure mercury lamp can prevent blackening of an inner wall of the transparent envelope from occurring over a long period of lighting without deteriorating the startability or lamp characteristics, thus achieving a long life.

Abstract: A discharge lamp which maintains a high lumen maintenance factor even when operated for a long time is obtained in a discharge lamp which has a silica glass discharge vessel and a pair of opposed electrodes in the discharge vessel and in which the discharge vessel is filled with at least 0.15 mg/mm3 mercury, a rare gas with argon as the main component, and 2×10?4 ?mole/mm3 to 7×10?3 ?mole/mm3 bromine by meeting the following conditions when feeding a direct current of 5 mA between the electrodes and a glow discharge produced: 1.0×10?4?b/a?1.2×10?1??Condition (1) c/a?1.4×10?1??Condition (2) d/a?1.2×10?2??Condition (3) e/a?1.4×10?2??Condition (4) where a is the emission intensity of the argon with a wavelength of 668 nm, b is the emission intensity of OH with a wavelength of 309 nm, c is the emission intensity of hydrogen (H) with a wavelength of 656 nm, d is the emission intensity of C2 with a wavelength of 517 nm, and e is the emission intensity of CH with a wavelength of 431 nm.

Abstract: A light source comprises: (a) a source of plasma discharge that emits electromagnetic radiation, a portion of which has wavelengths shorter than about 200 nm; and (b) a phosphor composition that comprises particles, each of the particles comprising at least a first phosphor and at least a second phosphor, the phosphor composition is disposed such that the first phosphor absorbs substantially the portion of EM radiation having wavelengths shorter than about 200 nm, and the first phosphor emits EM radiation having wavelengths longer than about 200 nm.

Abstract: Superior color stability in a miniature HID lamp can be achieved by reducing the size of the lamp, reducing the mercury concentration, reducing the salt concentration and increasing the heat to the lamp seal. In general the result concentrates the salts in the central, lower section of the lamp envelope and displaces them from the hot spot and electrode roots were deleterious chemical reactions can occur that are believed to subsequently reduce lamp performance.

Abstract: A short arc ultra-high pressure mercury lamp, at least one of the electrodes of which has a melted part towards the electrode head and a coil part which extends from the melted part continuously and integrally with it in a direction away from the electrode head, avoids blackening of the tube wall and achieves a long service life by the provision of a power supply which supplies the discharge lamp with direct current when operation is starting and afterwards supplies it with an alternating current, the direct current supplied by the power supply to the discharge lamp being initially 0.3 to 0.6 times as great as the rated current and afterwards increasing to 1.0 to 2.0 times are great as the rated current.

Abstract: A metal halide fill for forming an ionizable fill comprising at least one inert gas, mercury, and at least one halogen, the fill additionally comprising the following constituents: Mn halide and V halide. This fill may in particular be present in the discharge vessel of a metal halide lamp.

Abstract: To devise an arrangement with relatively high pressure tightness, in a short-arc super-high pressure mercury lamp which is operated with an extremely high mercury vapor pressure, a light emitting part has a pair of opposed electrodes and is filled with at least 0.15 mg/mm3 of mercury; and side tube parts extend from opposite sides of the light emitting part, and in which the electrodes are partially hermetically sealed and are each welded to a respective metal foil, in the areas in which the electrodes are welded to the metal foils, the electrodes are deformed in the direction perpendicular to the metal foils to a degree of deformation that is at most 10%.

Abstract: A high-pressure discharge lamp comprises a lamp tube made of quartz glass and having a central portion formed in a spherical shape, and a pair of opposing tungsten electrodes inserted into the lamp tube. At least one of the tungsten electrodes is made of a tungsten material which contains more than 10 ppm of one of Co and Ni, or 10 ppm of Co and Ni in total, or a tungsten material which contains 20 ppm or more of at least two of Fe, Co and Ni in total, or a tungsten material which contains 20 ppm or more of Fe. Fe, Co and Ni belong to iron-group metals. The inter-electrode distance, i.e., distance between the leading ends of both tungsten electrodes is set to approximately 1-2 mm or less.

Abstract: A long-life high-pressure discharge lamp suffers reduced blackening and luminance drop even after it has been turned on over a long period of time, and is arranged to prevent the internal gases from leaking out and also to prevent the lamp bulb from being ruptured. The high-pressure discharge lamp has a pair of confronting electrodes inserted in a lamp bulb which confines therein at least mercury and a halogen gas. The lamp bulb contains oxygen at a partial pressure lower than a partial pressure which can maintain a luminance of 80% after 100 hours of operation and equal to or higher than 1.0×10?5 Pa.

Abstract: An arrangement with a relatively high pressure tightness in a super-high pressure mercury lamp which is operated with an extremely high mercury vapor pressure is achieved in accordance with the invention in a super-high pressure discharge lamp of the short arc type having a light emitting part in which a pair of electrodes are disposed opposite each other and which is filled with at least 0.15 mg/mm3 mercury; and side tube parts which extend from each side of the light emitting part and in each of which a respective one of the electrodes is partially hermetically sealed and is connected to a metal foil, by the area of the respective metal foil which is connected to the respective electrode has a smaller width than the width in the remaining area of the metal foil, the area with the smaller width wrapping at least partially around the outside surface of the electrode.

Abstract: The present invention provides a high pressure discharge lamp which is provided with a discharge tube containing a pair of electrodes therein and being filled with mercury, an inert gas and a halogen gas, the amount of the mercury filled being 0.12 to 0.35 mg/mm3, the halogen gas being at least one gas selected from the group consisting of Cl, Br and I and being present in an amount of 10?7 to 10?2 ?mol/mm3, and the electrodes being mainly composed of tungsten, and the tungsten as a material of the electrodes contains not more than 12 ppm of potassium oxide (K2O). In such a high pressure discharge lamp, blackening of the discharge tube due to the potassium oxide (K2O) contained in the tungsten, and decrease in illumination maintenance can be prevented, thus providing a high pressure discharge lamp with a long lifetime, a lighting optical apparatus using the high pressure discharge lamp as a light source, and an image display system using the lighting optical apparatus.