Abstract: The present invention describes an organic electroluminescent (EL) device and a method for manufacturing the same. The organic electro-luminescent (EL) device includes: a substrate; at least a first electrode formed on the substrate; at least a heat dissipation layer formed on the first electrode, wherein the heat dissipation layer includes a plurality of contact windows exposing portions of the first electrode; at least an organic layer formed to cross the heat dissipation layer partially, covering the exposed portions of the contact windows to contact the first electrode; and at least a second electrode formed on the organic layer. The heat generated in the organic layer during operation dissipates out of the active region of the device and thus the device lifetime is prolonged and the reliability is enhanced.

Abstract: The represent invention relates to a method of backlighting a liquid crystal display which includes heating a fluorescent lamp with an external heating element which does not contact the lamp. The heating step may be accomplished by passing a current through a resistive material. The resistive material may be coated on to a surface. The present invention also relates to a backlighting system with a fluorescent lamp and an external heating element which does not contact the fluorescent lamp. The heating element may be a resistive material coated on a substrate. The present invention also relates to a portable display device element includes a liquid crystal display, a fluorescent lamp to act as a backlight, a heating element which does not contact the fluorescent lamp and optionally including reflectors, diffusers, and optical enhancement films. The heating element may be a resistive material coated on a substrate.

Abstract: A CRT including an evacuated envelope with a color selection electrode assembly disposed within the envelope, and an internal magnetic shield (IMS) secured to the color selection electrode assembly, and having a replaceable getter attachment assembly comprising a mounting rail and replaceable getter portion. The mounting rail having a first portion with a coupling clip attached to the IMS and a second portion extending therefrom. The replaceable getter portion includes a first end extending from the mounting rail with a getter cup attached thereto and a second end detachably attached to the second portion of the mounting rail. The replaceable getter portion extends from the mounting rail to deposit a film of evaporated getter material therefrom within the envelope.

Abstract: An image forming apparatus includes an envelope formed by first and second substrates disposed at a predetermined distance therebetween and an image forming member disposed in the envelope. A heat insulating member is disposed on a surface of the envelope in an area excepting partial surface areas of the first and second substrates.

Abstract: A cooling structure of a projection tube having a following constitution is disclosed. A chamber in which a liquid coolant for cooling a panel surface is filled is formed on the panel surface of the projection tube and the chamber is defined by the panel surface, a lens which faces the panel surface in an opposed manner and a metal envelope which radiates heat. A first seal member is disposed between the metal envelope and the panel surface, while a second seal member is disposed between the metal envelope and the lens. A holder for pressing the lens in the direction toward the metal envelope is disposed in the periphery of the lens. Pads which have surfaces approximately perpendicular to a tube axis of the projection tube are formed on a funnel portion of the projection tube. A sustainer for supporting the chamber is brought into contact with the pads.

Abstract: A coupler for coupling a projection lens to a cathode ray tube consists of a metallic plate having a first side and a second side, the first side for mounting to the faceplate of the cathode ray tube in a fluid tight relationship and the second side for mounting to a lens plate. The metallic plate is covered with a non-reflective coating and has at least one through hole for mounting to CRT rails. A plurality of ribbs protrude from the second side of the metallic plate from at least one of the at least one through holes and the ribbs surround the through hole. Upon mounting of a fastening device in the at least one through hole, the fastening device comes into contact with a top surface of the ribbs and the non-reflective coating is removed from the ribbs, thereby forming a ground connection for the coupler.

Abstract: Disclosed is a LED which can be mounted at high density on a large area display. Having a hole for heat sink in the ceramic substrate, the LED is superior in heat sink property. In order to fabricate the light emitting device, first, a secondary ceramic sheet is stacked on the ceramic substrate, followed by forming electrodes in a predetermined pattern on the secondary ceramic sheet around the hole for heat sink. On the ceramic substrate, an upper ceramic sheet with an opening is stacked to form a stacked ceramic substrate in such a way that a part of the electrodes are exposed through the opening. After co-firing the stacked ceramic substrate, a light emitting diode chip is mounted on the secondary ceramic sheet at a position corresponding to the hole for heat sink. Then, the electrodes are electrically connected with the LED chip, and the LED chip is sealed with insulating resin. A light emitting device using the LED and a fabrication method therefor are also disclosed.

Abstract: A coating start point is altered to avoid flowing of a sealing resin to an EL element when the sealing resin is pressed and flattened on adhesion of a device substrate and a sealing substrate with the sealing resin interposed therebetween. In a manufacturing method of a display device of the invention which is formed by adhering the device substrate and the sealing substrate with the sealing resin interposed therebetween, when the sealing resin is coated along edges of the device substrate and the sealing substrate, the coating is started on a corner of the substrates as a coating start point and a coating end point is on the same corner as for the coating start point.

Abstract: Disclosed is a heat dissipating system of a plasma display device. The heat dissipating system of the plasma display device includes a plasma display panel and a main frame, which is arranged in parallel to the plasma display panel and radiates heat generated in the plasma display panel. The main frame has at least one groove part, and the plasma display panel and a first support inserted through the groove part are adhered by adhesive means. The first support and the main frame are fixedly supported by a second support. As a result, the present invention has advantages of achieving high heat dissipating effect by making an interval between the main frame and the plasma display panel possible to be reduced or almost eliminated, and of achieving an easy detachment between the main frame and the plasma display panel.

Abstract: A flat fluorescent lamp is provided with one or more protrusions at the periphery thereof, which protrusion(s) extends outwardly beyond the edges of the two glass plates. A lamp holder receives the protrusion of the flat fluorescent lamp so as to hold the same in a manner that no edges of the two parallel glass plates touch or come into contact with the lamp holder.

Abstract: Passive heat transfer apparatus is provided for an X-ray imaging system used in connection with mammaography, to rapidly conduct heat away from the system X-ray tube. The apparatus comprises a thermally conductive support plate located in the tube housing, in spaced apart relationship with the X-ray tube, and further comprises an elongated device for transferring heat by convection, such as a heat pipe. The heat transfer device has a first end joined to the tube, and a second end joined to the support plate. A quantity of selected working fluid sealably contained in the heat transfer device is disposed to transfer heat along the length thereof, from the tube to the support plate, and cooling fins extending through the housing from the support plate dissipate the heat into the surrounding environment.

Abstract: The present invention provides a bulb attachment for a temperature limited environment. According to the invention, a sleeve is attached to a bulb in a bulb/reflector assembly. As the lamp operates, heat is diverted from the hottest portions of the bulb and into the sleeve, which results in a lower surface temperature of the bulb and allows compliance with UL standards. In some cases, the use of the sleeve allows for the use of higher power bulbs (and the associated increases in light output and brightness) without violating UL standards.

Abstract: The plasma display device including a plasma display panel, a chassis base disposed substantially parallel to the plasma display panel, and a thermally conductive medium which is disposed between the plasma display panel and the chassis base, and closely adhered to both the plasma display panel and the chassis base. The thermally conductive medium is formed out of gel-like adhesive materials.

Abstract: An apparatus 1 for capturing heat from a light globe 9 is disclosed. The apparatus 1 comprises: a transparent or translucent internal sheath 19 adapted to fit around the globe 9, the internal sheath defining a first space 20; a transparent or translucent external sheath 29 mounted around and spaced from the internal sheath 19 so as to define a second space 30 between the sheaths; and an aperture 10 through the internal sheath 19 providing communication between the first and second spaces. A fluid inlet 4 and a fluid outlet 5 are provided to enable fluid to be circulated through the spaces to capture heat from the light globe 9.

Abstract: A coupler for coupling a projection lens to a cathode ray tube consists of a metallic plate having a first side and a second side, the first side for mounting to the faceplate of the cathode ray tube in a fluid tight relationship and the second side for mounting to a lens plate. The metallic plate is covered with a non-reflective coating and has at least one through hole for mounting to CRT rails. A plurality of ribbs protrude from the second side of the metallic plate from at least one of the at least one through holes and the ribbs surround the through hole. Upon mounting of a fastening device in the at least one through hole, the fastening device comes into contact with a top surface of the ribbs and the non-reflective coating is removed from the ribbs, thereby forming a ground connection for the coupler.

Abstract: Disclosed is a heat dissipating system of a plasma display device. The heat dissipating system of the plasma display device includes a plasma display panel and a main frame, which is arranged in parallel to the plasma, display panel and radiates heat generated in the plasma display panel. The main frame has at least one groove part, and the plasma display panel and a first support inserted through the groove part are adhered by adhesive means. The first support and the main frame are fixedly supported by a second support. As a result, the present invention has advantages of achieving high heat dissipating effect by making an interval between the main frame and the plasma display panel possible to be reduced or almost eliminated, and of achieving an easy detachment between the main frame and the plasma display panel.

Abstract: A coolant buffering apparatus of a CRT that buffers expansions and contractions of a coolant held in a coupler installed between the CRT and a projection lens unit. The apparatus has a cylinder connected to the coupler so that coolant in the coupler can flow into the cylinder, a piston assembly installed to be operative to reciprocate in the cylinder and pushed in a direction away from the coupler as coolant expands, and a spring for elastically biasing the piston assembly toward the coupler when the coolant contracts.

Abstract: A light source system includes a heat sink. A base connector receives electrical power. A housing is secured to the base connector. A ballast unit is secured within the housing and electrically connected to the base connector. At least one electrical component is both mechanically and electrically connected to the ballast unit. The at least one electrical component is driven by the electrical power received by the base connector. A lamp unit is secured to the housing and electrically connected to the ballast unit. An additional electrical component includes a portion which contacts an inside wall of the housing. The additional electrical component is electrically connected to the ballast unit and has a life span which decreases as an operating temperature of the additional electrical component increases. The inside wall of the housing acts as the heat sink for the additional electrical component.

Abstract: A liquid cooling type cathode-ray tube for a projector comprising a coupler (43) mounted on the front surface (42a) of a cathode-ray tube body (42), which coupler serves as a cooling liquid sealing member and which is sealed with a cooling liquid (46) therein, the coupler (43) having a liquid fill hole (53) and a diaphragm (51) as a pressure regulating valve on the front surface thereof, and all of the mounting bores provided through the coupler being formed in the tubular axis direction of the cathode-ray tube body (42).

Abstract: There can be avoided a contrast degradation caused by stray light generated from a liquid-cooling type cathode-ray tube apparatus incorporated in a projection type television apparatus. Stray light (7) emitted from a flange (peripheral edge) (11a) of a lens (11) out of a coupler (10) and the lens (11) disposed on the front face of a CRT 1 of a liquid-cooling type cathode-ray tube apparatus 5 is shield by light shielding members (ribs) (20), (20a) disposed in the coupler (10) and/or a lens plate (13).

Abstract: A cylindrical graphite electrode with a consumable end includes one or more slots comprising a discontinuous portion of the carbon which extend along the length of the carbon body through at least a portion of the cross-section substantially to the consumable end. The slot may extend from the surface into the body or the slot may extend within the body below the surface. The slot may be filled with a carbonaceous material different from the carbon of the body. The slot may extend helically along the length and around a portion of the periphery of the body. The slots may be formed prior to or after heat treating of the electrode. As the electrode is exposed to a thermal shock, a crack is initiated in and propagates along the electrode and intersects with the slot, wherein substantial further growth of the crack is arrested at the slot.

Abstract: An apparatus for cooling an electrodeless lamp including a supersonic outlet jet for providing a stream of cooling gas. A common manifold including mounting elements for a plurality of conduits of equal length for transporting cooling gas, wherein the mounting elements are at staggered elevational positions so that the conduits provide cooling gas in the vicinity of lamp envelope at different elevational positions.

Abstract: A plurality of a U-shaped heat radiation plates are provided on a heat radiating tube. These U-shaped plates have different sizes and elongated in the same direction so as to cross an axis of the tube. The emissive heat radiator may also includes at least one radiating plate 2 substantially perpendicular to each axis of the U-shaped plates. A concave surface of the U-shaped plate is subjected to a radiation surface processing, and a convex surface thereof is subjected to a reflection surface processing.

Abstract: An electrodeless high intensity discharge lamp includes a light-transmissive arc tube for containing a plasma arc discharge, the arc tube having a top and a bottom and a side wall with a fill disposed therein. The fill includes at least one metal halide and a buffer gas. The arc tube has a wall with an interior surface having an annular region around the central extent of the side wall. The interior surface of the arc tube wall is smooth over the majority of its extent but has a liquid-stabilizing roughened surface in the annular region.

Abstract: An image display apparatus includes a display panel formed by arranging in juxtaposition a face plate carrying thereon a phosphor and a rear plate carrying thereon electron-emitting devices within a housing. The phosphor is so arranged as to be irradiated with electrons emitted from the electron-emitting devices to display images. The image display apparatus further includes an air blower for causing air to flow between the display panel and the housing.

Abstract: Ignition of an electrodeless lamp, energized by microwave or radio frequency energy, is achieved by disposing a ferroelectric igniter in the lamp envelope along with the fill material. The igniter responds to switching of its spontaneous ferroelectric polarization by emitting electrons that collide with the atoms of the fill material to discharge further electrons and ultimately provide emission of light. In the preferred embodiment, the microwave or radio frequency energy used to excite the fill material is applied to the ferroelectric igniter to cause switching of its spontaneous ferroelectric polarization. Another preferred feature is the securing of the igniter, in the form of a thin patch or wafer, to the inside surface of the lamp envelope in a generally perpendicular orientation to the electric field in the microwave excitation energy.

Abstract: Disclosed is a control mechanism for regulating the temperature of a fluorescent lamp tube located within a housing. The control mechanism includes a cold spot mechanism defining the cold spot of the lamp tube, a heating mechanism, a power supply and a temperature sensor. The heating mechanism is connected to the power supply and is contiguous with a portion of the cold spot mechanism located outside of the housing. The temperature sensor is also coupled to the power supply and monitors the temperature of the cold spot mechanism. Based upon the temperature of the cold spot mechanism, the temperature sensor operates the power supply, so as to deliver power to the heating mechanism to warm the cold spot mechanism and maintain a cold spot temperature that allows the lamp tube to generate maximum visible light output.

Abstract: A fluorescent-lighting adaptor assembly for a fluorescent lamp which has at least one light-emitting tube, a base, and electrical contacts on said base includes an electrical adaptor and a heat sink. The electrical adaptor includes an enclosure and electrical sockets configured to receive the lamp contacts on the enclosure. The enclosure defines at least two housing portions radially separated by at least one window and a ballast in at least one of the housing portions. The heat sink includes a wall surrounding the light-emitting tube, a heat coupling surface of the wall facing the light-emitting tube and configured to couple heat between the light-emitting tube and the wall, and a heat dissipation surface. The heat dissipation surface of the wall is positioned in the window between the enclosure portions and is configured to dissipate heat to the atmosphere.

Abstract: An original illuminating apparatus for use in a copying apparatus, an image reader, or a facsimile is provided with a fluorescent lamp having a long tube wall to illuminate an original; a heat radiating member provided at a position opposite to the original illuminating side of the fluorescent lamp; and a thermal coupling member which is close to the tube wall of the fluorescent lamp and the heat radiating member and is thermally coupled thereto. The thermal coupling member is provided within an effective light emission length in the longitudinal direction of the fluorescent lamp at a position different from the original illuminating side of the fluorescent lamp or on the side that is almost opposite to the original illuminating side of the fluorescent lamp.

Abstract: A compact fluorescent lamp is provided having a generally helically shaped lamp envelope wherein the two end segments of the lamp envelope extend radially inward from the pitch of the helix. The end segment extend into openings formed in a mounting cap member which is essentially dome-shaped at the center portion thereof. The mounting cap member can be constructed of two pieces each of which accepts one of the end segments of the lamp envelope. The mounting cap member is effective for reducing the amount of lamp envelope surface area that must be disposed within the housing of the lamp and is further beneficial in that light generated on the inside surface of the lamp can be reflected outward and more readily escape without losses due to multiple reflections or absorption.

Abstract: A spectral filter and mounting assembly comprising a flat quartz disk with coatings to control the light spectrum, a heat transfer adapter, a split-ring retainer for use in a drop-in arc lamp assembly that includes an arc lamp with fitted cathode and anode heat sinks each including a thin-wall copper strip that is brazed in pleated folds between inner and outer cylindrical rings to create cooling fins. The drop-in lamp assembly also includes an insulative sleeve in which the arc lamp and heat sinks are disposed and a pair of connection bushings piercing the wall of the sleeve and providing an electrical connection to the arc lamp outside the sleeve. The arc lamp includes a copper heat conduction flange that surrounds a front window reduced in diameter from the diameter of the arc lamp. The flange conducts heat generated in the window and the spectral filter during operation directly to the cathode heat sink. Both heat sinks are forced-air cooled by the fan, thus cooling the window and the spectral filter.

Abstract: A high-pressure discharge lamp provided with a discharge tube with a current lead-through member passing through an end of the discharge tube and provided with a heat shield around the end of the discharge tube. Also claimed is a heat shield suitable for use in a high-pressure discharge lamp. The heat shield comprises a bottom surface provided with tongues which are separated by incisions and which rest against the current lead-through member with a clamping force, in which position the tongues extend from the common bottom surface in a direction away from the discharge tube.

Abstract: In some embodiments, a light bulb for an electrodeless discharge lamp has a protuberance such that the cold spot of the bulb is located in the protuberance. The protuberance is spaced from the induction coil of the lamp so as to be easily accessible. Hence the cold spot temperature is easy to measure and control. In some embodiments, heat sinks are provided to cool the light bulb. An active control element including a Peltier element is provided to control the cold spot temperature.

Abstract: A high-intensity discharge lamp includes a luminous tube in which predetermined rare gases and metal are sealingly filled, and a pair of electrodes provided at the ends, wherein irregular portions are formed at both ends of the luminous tube which surround the electrodes, thereby enhancing color rendering and luminous efficiency, and reducing a starting voltage.

Abstract: A high pressure discharge lamp having a discharge vessel with opposing end chambers includes discharge electrodes each consisting of an open elongate filament of refractory metal wire having a plurality of succesive coil turns extending transverse to the longitudinal axis of the discharge vessel. The filament electrodes are dimensioned so that the discharge arc which terminates thereon is sufficiently retracted into the end chamber of the discharge vessel so that the fill constituents condense on a region of the discharge vessel which is primarily axially between the filament electrodes. In a favorable embodiment, the lamp is a metal halide lamp in which the electrode and the discharge sustaining fill is free of thoria and its compounds.

Abstract: To provide a fill in a low-power, high-pressure discharge lamp, which is capable of emitting light within a warm white light (WDL) color or neutral white light (NDL) color, that is, in the ranges of between about 2600 to 4600K, the fill has a relative relationship of sodium halide to scandium halide between 5:1 and 24:1, a relationship of sodium halide to thallium halide of 25:1 to 73:1, and a heat damming or heat retention or reflection coating (15, 16) is located at the end caps of the generally bulbous discharge vessel to provide for a cold spot temperature (Tc) of at least 800.degree. C., and preferably higher.

Abstract: The electrodeless low-pressure discharge lamp has a lamp vessel (1) having a cavity (2) at an end portion (3) thereof. An electric coil (4) surrounding a plastic sleeve (5), wherein a liquid-filled tubular container (7) surrounded by a soft-magnetic core (6) is present, is accommodated in the cavity (2). The plastic sleeve (5) is substantially filled up with an elastic polymer. Additionally, the tube (5) may be enveloped by an elastic polymer (9). The elastic polymer ensures a relatively low operating temperature of the members inside the cavity (4).

Abstract: In a UV high-power radiator, a plurality of dielectric tubes (6) having internal electrodes (7) are disposed in the interior of a quartz housing having rectangular cross section. The interior of the housing is filled with a filling gas which emits UV radiation under discharge conditions. The electrical supply is provided in such a way that the discharges (17) develop between adjacent dielectric tubes (6). A notable feature of this construction is its compactness, economical nature and service friendliness.

Abstract: To provide a high-pressure lamp capable of carrying lamp currents of 100 eres and higher, an essentially rotation-symmetrical discharge space (2) has two cylindrical necks (3, 4) melt-sealed thereto. Each one of the necks is formed of at least two telescoped hollow cylindrical quartz glass tubes (19, 27) which, with sealing foils circumferentially located within the neck, are all gas-tightly melt-sealed together. The sealing foils, typically of molybdenum, are electrically connected to a molybdenum disk (7, 8), for example by being welded to the circumference thereof which, in turn, is soldered to an end portion of an electrode shaft (5, 6), typically of tungsten, which extends into the discharge space of the discharge vessel.

Abstract: A filter for absorbing radiation of a selected wave length emitted from a mercury vapor lamp is disclosed. The filter comprises a device for providing an ozone-containing gas layer positioned between the mercury vapor lamp and an object to be illuminated, which may be formed by providing a transparent space filled with the ozone-containing gas between the lamp and the object. This provides a relatively large sized filter which has a simple construction.

Abstract: An electron-beam tube with an electron collector for an electron-beam entering the electron collector in an electron-beam direction. A plurality of large-area projections are provided for heat radiation including a funnel-shaped projection expanding in the electron-beam direction. The funnel-shaped projection includes a smaller opening which is one of directly and indirectly fastened to the collector and including an upstream projection including a surface which is first with respect to the electron-beam direction, the surface facing the arriving electron-beam and the surface being provided with low heat radiation properties. All other surfaces of the plurality of projections having high heat radiation properties higher than the low heat radiation properties. The collector and the plurality of projections being supported by a satellite as a travelling-wave tube with the electron collector radiating into space.

Abstract: The high pressure discharge lamp has an elongate discharge vessel of ceramic material. The outside surface area of the wall of the discharge vessel is strongly increased by a relief. Since a higher heat flow from the discharge vessel to the environment is possible, the lamp can withstand a higher load. In this way, lamp properties such as luminous flux, color rendering index and/or color temperature can be improved.

Abstract: A low pressure gas discharge lamp of the capillary bore type is equipped with a temperature control system whereby the electrode containment section and the light output section of the lamp are at higher temperatures than the capillary bore section. Vapor flow from the higher temperature sections to the relatively low capillary bore section maintains a satisfactory vapor fill in the bore section for attainment of a high light output. In one arrangement, the temperature control system includes a heater and a heat sink at selected points along the lamp envelope. In another form of the invention, the control system is solely a heat sink in thermal contact with the capillary bore section.

Abstract: Heat sink means are provided for a metal halide lamp to enable more light output during lamp start-up. A xenon-metal halide lamp employing the heat sink means is disclosed along an with automotive headlamp having this lamp for its light source.

Abstract: In a fluorescent lamp assembly for use in an image scanner, a heater is associated with a glass tube of a fluorescent lamp for heating the glass tube. A controller is provided for controlling the heater in such a manner as to maintain temperture of the glass tube at the predetermined optimum level at which a luminescent characteristic of the fluorescent lamp is stabilized.

Abstract: In a lighting fixture including a lamp and a housing, a heat transfer structure is disclosed for reducing the minimum lamp wall temperature of a fluorescent light bulb. The heat transfer structure, constructed of thermally conductive material, extends from inside the housing to outside the housing, transferring heat energy generated from a fluorescent light bulb to outside the housing where the heat energy is dissipated to the ambient air outside the housing. Also disclosed is a method for reducing minimum lamp wall temperatures. Further disclosed is an improved lighting fixture including a lamp, a housing and the aforementioned heat transfer structure.

Abstract: In a lighting fixture including a lamp and a housing, an improvement is disclosed for maintaining a lamp envelope area at a cooler, reduced temperature relative to the enclosed housing ambient. The improvement comprises a thermal element in thermal communication with the housing extending to and springably urging thermal communication with a predetermined area of the lamp envelope surface.

Abstract: The electrodeless low-pressure discharge lamp comprises a tube which is closed at one end, which surrounds a body of soft magnetic material with clearance, and which is enclosed with clearance in the cavity in the outer bulb, which cavity enters the cavity in the discharge vessel. The tube provides a good insulation of the body from the heat of the discharge in the discharge vessel.

Abstract: A microwave discharge light source device in which one side of a discharge space in which a plasma emission takes place is defined by a transparent dielectric member. A transparent microwave reflecting member is disposed in a position such as to face the discharge space through the dielectric member. A microwave having an electric field component in the direction of thickness of the dielectric member is introduced into the dielectric member through the coupling at an end surface of the dielectric member so that a microwave electric field is formed in the discharge space, and so that the plasma emission medium emits light by electric discharge. The light thus emitted is extracted through the transparent microwave reflecting member.

Abstract: A low-wattage metal-halide discharge lamp has a tube of the double ended type that forms a bulb or envelope, a pair of electrodes, e.g., an anode and a cathode, which penetrate into an arc chamber inside the envelope, and a suitable amount of mercury plus one or more metal halide salts. The electrodes are each formed of a refractory metal, i.e., tungsten wire, extending through the respective necks into the arc chamber. Heat transfer along the tube wall and through the necks is controlled by designing the bulb wall so that the cross sectional areas at the necks and at quarter-chamber planes halfway between the necks and a midplane have a respective quarter chamber loading factor and a neck loading factor each within a desired range. Lamps of this design achieve high efficacy at relatively low power, i.e., below 40 watts.