JP2002124214A - Discharge lamp and lighting system ! method of stabilizing dimension of tungsten filament - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp with suppressed temperature rising of an outer electrode and to provide a lighting system using this discharge lamp. SOLUTION: An inner electrode 3 is sealed on the inside of a slender, translucent air-tight vessel 1, a discharge medium with main component of rare gas is sealed in the container, a conductive metal wire having 100 W/m.k (0 deg.C) or more heat conductivity is spirally wound and nearly brought into contact with the outer circumferential surface of the translucent air-tight vessel 1 extended in the length direction, and the outer electrode 6 causing discharge between the inner electrode 3 and itself is installed. As the conductive metal constituting the outer electrode 6, for example, copper, aluminum, tungsten and molybdenum are listed. Since the heat conductivity of the conductive metal constituting the outer electrode 6 is high, temperature rising of the outer electrode 6 and the translucent air-tight vessel 1 is suppressed, and reliability of the discharge lamp is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a discharge lamp in which a discharge medium mainly composed of a rare gas is sealed, and a lighting device using the same.

2. Description of the Related Art Discharge lamps containing a rare gas such as xenon gas do not use mercury, which has a large environmental burden,
There is an advantage that the environment at the time of disposal is small, and the brightness and the discharge voltage are hardly affected by the ambient temperature.

[0002] As a discharge lamp utilizing rare gas discharge,
A phosphor layer is formed on the inner surface of a straight tube-shaped glass tube, and a short internal electrode is supported and sealed at the inner end of a lead-in wire that is sealed through one end of the glass tube. A structure in which a coil-shaped external electrode is wound in contact with a member has been developed. The external electrode is formed using a nickel wire having a wire diameter of 0.1 mm. Further, a transparent heat-shrinkable tube is coated from the outside of the external electrode to fix and protect the external electrode.

In this discharge lamp, by applying a voltage between the internal electrode and the external electrode,
A rare gas discharge is generated inside the glass tube, ultraviolet rays are emitted, and the ultraviolet rays irradiate the phosphor layer to excite the phosphor, so that visible light is emitted from the phosphor and wavelength conversion is performed, Visible light is led out of the glass tube. The visible light is used for illumination.

However, in a discharge lamp having an external electrode as described above, a discharge occurs between the internal electrode and the external electrode through a glass tube, so that the temperature of the external electrode is reduced. As a result, there is a problem that the heat-shrinkable tube covering the outside of the external electrode is deteriorated.

[0004] It is an object of the present invention to provide a discharge lamp in which a rise in the temperature of an external electrode is suppressed and a lighting device using the same.

[0005]

A discharge lamp according to the first aspect of the present invention comprises an elongated light-transmitting airtight container; an internal electrode sealed inside the light-transmitting airtight container; and a light-transmitting airtight container. A discharge medium mainly composed of a rare gas obtained;
A conductive metal wire of W / m · K (0 ° C.) or more is wound in a coil shape and almost contacts the outer peripheral surface of the light-transmitting airtight container and extends in the longitudinal direction. And an external electrode that generates a discharge between the external electrodes.

In the present invention and the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified. The following is a description of each component.

<Translucent airtight container> A translucent airtight container is preferably formed by sealing both ends of a glass bulb because it is the easiest to manufacture and the cost is low. It may be formed of optical ceramics or the like. Note that as the glass, soft glass, semi-hard glass, hard glass, quartz glass, or the like can be appropriately selected and used. The fact that the light-transmitting airtight container is light-transmitting does not require that the entire light-transmitting airtight container be light-transmitting, but at least a portion where light generated due to electric discharge is to be derived. Means that it is translucent. In addition, that the light-transmitting airtight container is elongated means that the light-transmitting airtight container has a length that is at least twice the outer diameter of the discharge container.

Further, the light-transmitting airtight container may have any of a straight tube shape and a non-straight tube shape, that is, an irregular shape. The “irregular shape” means that the shape of the discharge vessel in the longitudinal direction is not a straight pipe shape. Various shapes such as L-shape, U-shape, U-shape, W-shape, ring shape, and semi-annular shape can be adopted as the deformed shape. Further, not only the above-described two-dimensional shape but also a three-dimensional arbitrary curve can be obtained. Furthermore, in order to form a deformed shape, after heating a straight tube-shaped glass tube, it can be curved by applying an external force, or can be curved using a molding die. When the discharge vessel has an irregular shape, it is possible to configure a single discharge lamp so as to simultaneously enter a light guide plate of a liquid crystal backlight device from two or more sides thereof. That is, the discharge lamp that performs rare gas discharge has a smaller amount of light than the discharge lamp that performs mercury vapor discharge, so it is necessary to lengthen the discharge vessel to increase the amount of light.
Therefore, it is conceivable to arrange a plurality of discharge lamps in the shape of a straight tube on a plurality of end faces of the light guide plate to compensate for the insufficient light amount. However, this configuration increases the cost and increases the backlight of the discharge lamp. Incorporation into the device becomes difficult, for example, in terms of wiring and supporting the discharge lamp. On the other hand, by making the discharge vessel longer and having a different shape, a single discharge lamp can be configured to simultaneously receive light from a plurality of end faces. For this reason, the cost can be reduced, and the incorporation into the backlight device becomes easy. On the other hand, since the amount of light emission can be increased by lengthening the discharge vessel, higher luminance can be obtained as compared with the case where one straight tube-shaped discharge lamp is used.

Furthermore, in the present invention, the translucent airtight container may have a non-circular shape such as a flat or elliptical cross section.

<Regarding Discharge Medium> The discharge medium is mainly composed of a rare gas, and the rare gas is allowed to be xenon, neon, argon, krypton, or the like. Further, in addition to the rare gas, a halide or a simple halogen of the rare gas may be added. As the halogen, iodine, bromine, and chlorine can be used. If the element exists as vapor in the range of several mmHg to several atmospheres, discharge is possible.

As will be described later, when a rare gas generates ultraviolet rays by electric discharge such as xenon,
A phosphor layer that is excited by ultraviolet rays and generates visible light can be provided on the inner surface side of the translucent airtight container.

<Regarding the Internal Electrode> The internal electrode is an electrode sealed in a translucent airtight container, and may be either a single electrode or a plurality of electrodes. Further, the internal electrode may be either a cold cathode or a hot cathode. Further, the internal electrode may have either a short configuration or a long configuration.

As the short internal electrode, a short electrode similar to that used for a normal internal electrode type fluorescent lamp can be used. When there is a single internal electrode, it can be sealed inside one end of the translucent airtight container. However, if necessary, it may be sealed in the middle of the translucent airtight container. When a pair of internal electrodes is used, the internal electrodes can be sealed inside both ends of the translucent airtight container. When three or more internal electrodes are sealed, for example, in addition to the above, the internal electrodes can be disposed at an intermediate position of the light-transmitting airtight container.

[0014] The elongated internal electrode has a length extending over substantially the entire length of the translucent airtight container in the longitudinal direction. A structure in which both ends of the internal electrode penetrate both ends of the translucent airtight container in an airtight manner and are led out to the outside, and only one end of the internal electrode penetrates one end of the translucent airtight container in an airtight manner and However, there is a one-end supporting structure in which the other end is located inside the vicinity of the other end of the translucent airtight container.

Further, in order to seal the internal electrode at the end or intermediate portion inside the translucent airtight container, various known sealing means such as a flare seal, a bead seal, and a pinch seal can be appropriately selected and used. . Furthermore, an emitter substance (electron-emitting substance) can be applied to the surface of the internal electrode for the purpose of reducing the power loss (power loss based on the cathode drop voltage) due to the electrode.

<Regarding External Electrode> The external electrode is formed by winding a conductive metal wire in a coil shape, substantially contacting the outer peripheral surface of the light-transmitting discharge vessel, and extending in the longitudinal direction. I have. The conductive metal has a thermal conductivity of 100 W
/ M · K (0 ° C) or more, preferably 130 W / m · K (0 ° C).
° C) or higher. Metals satisfying this condition include, for example, copper, aluminum, tungsten and molybdenum. Further, an alloy containing these metals as main components and having a thermal conductivity of 100 W / m · K (0 ° C.) or more, for example, brass may be used. However, an alloy containing another metal as a main component can be used as long as it is conductive and the thermal conductivity satisfies the above conditions. In the present invention, the reason for limiting the thermal conductivity of the conductive metal constituting the external electrode to 100 W / m · K (0 ° C.) or more is that if the temperature falls within this range, a substantial temperature reduction of the external electrode can be obtained. On the other hand, if it is less than this, there is no substantial difference from the external electrode using conventional nickel.

Further, one or more external electrodes are allowed to be arranged so as to form a pair with one or more internal electrodes. Then, a lighting circuit is connected between the paired external electrode and internal electrode. When a plurality of external electrodes and a plurality of internal electrodes are provided, they may be commonly connected to a single lighting circuit, that is, connected in parallel, or may be insulated from each other and conductively independent, Alternatively, it may be connected to a plurality of lighting circuits which are conductively connected.

Further, the pitch of the coil of the external electrode can be set as desired. Since the pitch of the coil of the external electrode affects the obtained luminance and illuminance, in order to realize a desired luminance or illuminance distribution in the tube axis direction,
The pitch of the coil can be changed appropriately. For example, when the pitch of the coil of the external electrode is constant in the tube axis direction, the luminance is relatively large in a region relatively close to the internal electrode, and the luminance is relatively large in a region relatively far from the internal electrode. Since it tends to be smaller, the pitch of the coil can be changed continuously or stepwise according to the distance from the internal electrode in order to obtain a distribution of luminance or illuminance as uniform as possible in the tube axis direction. In addition, when the tube current is increased and exceeds a certain threshold, the positive column changes from the diffused state to the contracted state from the portion on the side of the internal electrode, and the luminance of the portion facing the contracted positive column relatively decreases. . In order to increase the brightness of the portion facing the contracted positive column, which is generated when the tube current is increased, and to obtain a uniform brightness distribution as much as possible, the pitch of the coil of the external electrode in the portion facing the contracted positive column It is effective to reduce. But,
If necessary, the pitch of the coil of the external electrode can be appropriately changed even when it is desired to obtain a non-uniform brightness distribution controlled in the tube axis direction.

The external electrode is fixed to the light-transmitting discharge vessel and wound around the outer periphery of the light-transmitting discharge vessel while rotating the conductive metal wire therearound, or by placing the conductive metal wire at a fixed position. An external electrode can be provided by rotating and winding the translucent discharge vessel, or by winding both while rotating.

Further, a spring metal having a certain degree of elasticity is used as the conductive metal wire, and the external electrode is formed by forming the coil into a coil shape and inserting a light-transmitting discharge vessel into the coil. It can also be arranged.
In this case, the inner diameter of the coil-shaped formed body can be made smaller than the outer shape of the translucent discharge vessel, or conversely larger. If small, when inserting the translucent discharge vessel,
If the both ends of the coil are forcibly rotated in the rewinding direction, the inner diameter of the coil-shaped molded body increases, so that the light-transmitting discharge vessel is inserted therein, and then the rotation is released. Due to its own elasticity, it comes into close contact with the outer periphery of the translucent discharge vessel. On the other hand, in the case of a large size, the transparent electrode is inserted into the coil-shaped molded body, and then both ends are rotated in the coil winding direction, so that the external electrode is placed on the outer periphery of the transparent container. The external electrodes can be temporarily fixed by applying an adhesive or the like, and then fixed.

Further, the external electrode is disposed substantially in contact with the outer peripheral surface of the light-transmitting airtight container as described above. Therefore, the external electrode is fixed to the discharge vessel by an appropriate means. For example, the coil can be fixed to the discharge vessel by partially bonding both ends of the coil of the metal wire to the discharge vessel with an adhesive. When the adhesive is opaque or low opaque, it is partially, that is, spot-shaped, at both ends of the coil and at positions where the light distribution characteristics of the discharge lamp are less affected. An adhesive may be applied to fix the coil. On the other hand, when the coil is fixed at an intermediate position, it is preferable to use a translucent, preferably transparent adhesive. Of course, it is needless to say that a light-transmitting adhesive can also be used when applied to the end of the coil. However, alternatively or additionally, the coil can be fixed to the discharge vessel by tightly winding the winding start portion for a few turns. It can also be fixed by potting a transparent synthetic resin or mechanically tightening it.

Further, the coil made of a conductive material preferably has a resistivity of 2 × 10 ⁻⁴ Ω / cm or less from the viewpoint of reducing the power loss of the external electrode.

<Combined arrangement of internal electrode and external electrode> The internal electrode and the external electrode have been individually described above. Next, the combined arrangement thereof, that is, the internal and external electrode arrangement will be described.

The internal / external electrode type arrangement is an electrode arrangement in which one or a plurality of internal electrodes and one or a plurality of external electrodes are paired. In addition, this arrangement is divided into a short internal electrode and a long internal electrode extending along the longitudinal direction of the translucent airtight container.

(1) Electrode arrangement using short internal electrodes (1-1) A single internal electrode is arranged at one end of a translucent airtight container, and a single external electrode is disposed on the outer surface of the translucent airtight container. (1-2) An electrode arrangement in which a pair of internal electrodes are arranged at both ends of a translucent airtight container, and a single external electrode is arranged on the outer surface of the translucent airtight container. A configuration in which a pair of internal electrodes are both connected to one pole of the lighting circuit and an external electrode is connected to the other pole of the lighting circuit, and a pair of lighting circuits are prepared and one pole of each lighting circuit is separately connected to the internal electrode There is a configuration in which the external electrode is connected to the other electrode of the pair of lighting circuits at the same potential.

(1-3) An electrode arrangement in which internal electrodes are arranged at both ends of a light-transmitting hermetic container and a pair of external electrodes are arranged on the outer surface of the light-transmitting hermetic container. Are arranged one-to-one.

(1-4) Arrangement of internal electrodes at both ends and middle of the light-transmitting hermetic container, and arrangement in which a single external electrode is commonly opposed (1-5) Both ends and middle of the light-transmitting hermetic container An electrode arrangement in which a plurality of external electrodes individually facing the internal electrodes are arranged on the outer surface of the translucent discharge vessel. (2) An electrode arrangement using a long internal electrode. Electrode arrangement for arranging and arranging a single external electrode on the outer surface of the translucent airtight container Next, the power receiving means of the external electrode will be described.

One end of the coil can be directly led out to receive power from the external electrode. Instead, the base end of the lead wire is sealed to one end of the translucent airtight container so as not to be exposed to the discharge space, and one end of the coil is connected to this lead wire by soldering, caulking or welding. can do.

<Other Configurations> The following configurations can be appropriately adopted as required.
Therefore, it is not essential for practicing the present invention.

1. About Translucent Insulating Coating In order to mechanically fix the external electrode and, if necessary, further improve the insulating properties of the discharge lamp, a translucent insulating coating can be provided outside the external electrode. The translucent insulating coating is preferably transparent. The light-transmitting insulating coating can be formed by one or a combination of various means such as heat shrinkage of a light-transmitting insulating tube, winding of a light-transmitting insulating sheet, and dipping of a light-transmitting insulating resin solution. it can.

2. Regarding the phosphor layer As described above, when the rare gas emits ultraviolet rays by discharge and uses visible light, the phosphor layer can be disposed on the inner surface side of the translucent airtight container. . When the discharge lamp is used for a backlight, a phosphor emitting white light such as a phosphor of a three-wavelength emission type or a halophosphate phosphor is preferable.
In the case of reading, a phosphor that emits green light is preferable in the case of monochrome, and a phosphor that emits white light of a three-wavelength type is preferable in the case of full color. In short, the emission color of the phosphor may be appropriately selected depending on the use of the discharge lamp.

Further, the phosphor layer may be formed on the entire peripheral surface of the light emitting region in the longitudinal direction of the light-transmitting airtight container, or by forming a light guide slit in which the phosphor layer is not formed in the tube axis direction. An aperture structure can also be used.

3. About a protective film etc. If necessary, a protective film or an electron emitting material film made of alumina fine particles or the like can be formed on the inner surface of the translucent airtight container. When forming a protective film, a protective film may be formed between the phosphor layer and the inner surface of the translucent airtight container, or a protective film may be formed on the inner surface of the phosphor layer on the discharge space side. Is also good.
In addition, an electron emitting material film can be formed, and in this case, it is effective to avoid or reduce the occurrence of dark characteristics of the discharge lamp.

<Operation of the Present Invention> Since the present invention has the above configuration, the internal electrode and the external electrode are connected to a lighting circuit, and when a required voltage is applied between the internal and external electrodes, light transmission is achieved. A dielectric barrier discharge of a rare gas using the wall surface of the conductive discharge vessel as a dielectric is generated in the translucent discharge vessel, and ultraviolet rays or visible rays are emitted. Therefore, the radiation can be used directly or the ultraviolet light can be converted into visible light by the phosphor layer to be used.

Further, since the wire constituting the external electrode is a conductive metal having a thermal conductivity of 100 W / m · K (0 ° C.) or more, the external electrode has good thermal conductivity, and thus promotes heat radiation. Therefore, the temperature rise of the external electrode and the light-transmitting airtight container is reduced. For this reason, even if a light-transmitting insulating coating such as a heat-shrinkable tube is disposed outside the external electrode, thermal deterioration of the light-transmitting insulating coating is reduced, so that the temperature rise of the light-transmitting airtight container is reduced. Together with this, the reliability of the discharge lamp is improved.

Furthermore, since the rare gas discharge of the inner and outer electrode type is generated at the periphery of the conductive portion of the external electrode, the provision of the coil-shaped external electrode allows the conductive portion per unit length in the longitudinal direction of the discharge vessel to be provided. Therefore, since the portion where the discharge occurs becomes longer, the tube power per unit volume of the discharge space can be increased.

The discharge lamp according to the second aspect of the present invention is the first aspect of the present invention.
In the above-described discharge lamp, the external electrode is made of a conductive metal including at least one of a group of copper, aluminum, tungsten, and molybdenum.

The present invention defines a conductive metal suitable for forming an external electrode. That is, the conductive metal is
Any of the above-mentioned metal simple substance and an alloy containing one or more of these as a main component may be used.

Since copper is easily corroded and has some problems in strength, if necessary, a surface treatment such as electroplating of tin, nickel or the like or fusion plating of tin is performed to prevent corrosion and improve strength. Can be achieved.

It is also possible to use a composite metal in which a metal having excellent mechanical strength, such as stainless steel, is used as a core and a metal of the above group is clad around the core. In this case, the thermal conductivity of the core metal is 100 W / m · K (0
° C) or higher. In addition, the conductivity of the core metal may be lower than that of the metals in the above group.

Table 1 shows the thermal conductivity of the conductive metals in the above groups.

[0042]

Table 1 Metals Thermal conductivity (W / mK (0 ° C)) Copper 403 Aluminum 236 Tungsten 177 Molybdenum 139 Then, in the present invention, using a general metal which is relatively easily obtained, Since the temperature of the electrode can be lowered, implementation is easy.

According to a third aspect of the present invention, there is provided a discharge lamp.
Or the discharge lamp according to item 2, wherein the external electrode has a surface treated with a conductive metal wire.

In the present invention, "surface treatment" refers to modifying the surface of a conductive metal wire by means such as plating, chemical conversion, enamelling, painting, cladding, and the like. “Plating” includes electroplating, electroless plating, hot-dip plating, metal spraying, vacuum deposition, CVD, and the like. The “chemical conversion treatment” includes anodic oxidation, phosphate treatment and the like. The “enamelling treatment” includes glass lining. For example, surface treatment of copper wire
Tin can be surface-treated by electroplating or hot-dip plating. Further, alumite can be formed on the surface of the aluminum wire by anodic oxidation.

Thus, in the present invention, since the surface of the conductive metal wire is surface-treated, the surface of the conductive metal is modified and the durability of the external electrode is improved.

According to a fourth aspect of the present invention, there is provided a lighting device, comprising: a lighting device main body; a discharge lamp according to any one of the first to third aspects disposed on the lighting device main body; a lighting circuit for lighting the discharge lamp; It is characterized by having.

In the present invention, the term "illumination device" is a broad concept including all devices utilizing the light emission of a discharge lamp. For example, a backlight device, a liquid crystal display device having the same, and a liquid crystal display device are incorporated. Instrument panel lighting devices for mobile devices such as automobiles, decorative lighting fixtures, reading devices and image scanners, copiers and facsimile machines equipped with the reading devices. Examples of devices incorporating a liquid crystal display device include electronic devices such as personal computers, navigation devices, portable information terminals, and liquid crystal television receivers.

The “illumination device main body” refers to the remaining portion of the illumination device excluding the discharge lamp and the lighting circuit.

The lighting circuit preferably uses a power supply that outputs a high-frequency AC voltage having a waveform such as a rectangular wave or a sine wave, or a pulse voltage having a high repetition frequency. Note that the pulse voltage can be obtained by half-wave rectification of a high-frequency AC voltage of a rectangular wave or a sine wave. If multiple lighting circuits are required,
For example, this can be easily obtained by arranging a plurality of secondary windings in an output transformer of a common high-frequency inverter.

[0050]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing a first embodiment of the discharge lamp of the present invention.

FIG. 2 is a circuit diagram showing a front sectional view, a side sectional view and a lighting circuit.

In each figure, 1 is a translucent airtight container, 2 is a lead wire, 3 is an internal electrode, 4 is a lead wire, 5 is a phosphor layer,
6 is an external electrode, 7 is a translucent insulating coating, and 8 is a lighting circuit.

The translucent airtight container 1 has an elongated cylindrical portion 1a.
The first and second end portions 1b and 1c sealing both ends of the cylindrical portion 1a are integrally provided, have an elongated shape made of hard glass, and have a discharge space 1d formed therein. I have.

The first and second transparent airtight containers 1 are also provided.
Are formed mainly of glass bead stems. The first and second end portions 1b and 1c are formed by sealing a pair of bead stems at both ends of the glass tube of the cylindrical portion 1a. A discharge medium made of a rare gas mainly composed of xenon is sealed in the discharge space 1d.

The introduction wire 2 penetrates one end portion 1b of the light-transmitting airtight container 1 in an airtight manner, and the airtight penetrating portion is made of Kovar of a sealing metal. And it is comprised by welding a dumet wire to the outer end part of Kovar.

The internal electrode 3 is composed of a cold cathode,
And is sealed by welding at the end of one end of the translucent airtight container 1.

The lead wire 4 is sealed at the other end 1c of the translucent airtight container 1 so as not to be exposed to the discharge space 1d. The buried portion is formed of Kovar, and the protruding portion is formed of a dumet wire. ing.

The phosphor layer 5 is made of a phosphor of a three-wavelength emission type, and is formed on the inner surface of the light-transmitting airtight container 1.

The external electrode 6 is formed by winding a copper wire having a wire diameter of 0.1 mm in a coil shape, and the inner surface thereof is disposed in contact with the outer peripheral surface of the light-transmitting airtight container 1. .
Then, the wire is tightly wound two or three times on one end 1b side of the translucent airtight container 1, the winding start portion 6a is fixed, and the translucent airtight container 1 is rotated at a predetermined pitch. The connecting portion 6b is formed by extending the winding end portion. The connection portion 6b is connected to the lead wire 4 by soldering.

The light-transmitting insulating coating 7 is formed by heating a transparent heat-shrinkable fluororesin sheet into a tube shape.
The discharge lamp is configured by covering the translucent airtight container 1 from the outside of the external electrode 6.

The lighting circuit 8 is connected between the lead wire 2 and the lead wire 2 of the translucent airtight container 1. And it is comprised of an inverter and outputs a high-frequency rectangular wave pulse voltage.

Operation of the Discharge Lamp When a high-frequency pulse voltage is applied between the internal electrode 3 and the external electrode 6 of the discharge lamp from the lighting circuit 8 via the lead wire 2 and the lead wire 4, a voltage between the electrodes 3 and 6 is increased. A dielectric barrier discharge using the wall surface of the light-transmitting hermetic container 1 as a dielectric occurs in the discharge space 1d, and the xenon of the discharge medium sealed in the discharge space 1d of the light-transmitting hermetic container 1 emits ultraviolet light. Radiate. Since the ultraviolet rays irradiate the phosphor layer 5, the phosphor is excited to emit visible light. That is, ultraviolet light is wavelength-converted into visible light. The emitted visible light is led out from the gap formed between each turn of the coil of the external electrode 6 to the outside of the translucent airtight container 1 over the entire circumference, so that the visible light can be used as a lighting device. .

Hereinafter, another embodiment of the present invention will be described with reference to FIGS. In each figure, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted.

FIG. 3 is a front view showing a second embodiment of the discharge lamp of the present invention.

FIG. 4 is a circuit diagram showing the same front sectional view and lighting circuit.

The present embodiment is different from the first embodiment in that the pitch of the coil of the external electrode 6 gradually decreases as the distance from the internal electrode 3 increases. For this reason, the uniformity of the brightness distribution on the tube surface along the tube axis direction is improved.

FIG. 5 is a front view showing a third embodiment of the discharge lamp of the present invention.

FIG. 6 is a circuit diagram showing the same front sectional view, side sectional view and lighting circuit.

In the present embodiment, a pair of internal electrodes 3A, 3B are sealed inside both ends of the translucent airtight container 1, and a pair of lighting circuits 8A, 8B correspond to the internal electrodes 3A, 3B, respectively.
The main difference is that B is provided.

The external electrode 6 is single, and each internal electrode 3
A and 3B are provided in common.

The lighting circuit 8A is connected between the internal electrode 3A and the connection 6b of the external electrode 6. On the other hand, the lighting circuit 8B is connected between the internal electrode 3B and the connection portion 6b of the external electrode 6. In FIG. 5,
Reference numeral 9 denotes a wire harness, which is soldered to a connection portion of the external electrode 6.

Then, the inner electrode 3A and the outer electrode 6
And the inner electrode 3B and the outer electrode 6 operate as constituting individual discharge lamps, and as a result, the brightness distribution is more uniform along the tube axis direction of the translucent airtight container 1 and the light amount is large. Can be formed.

FIG. 7 is a sectional view showing a liquid crystal backlight device as one embodiment of the illumination device of the present invention.

In the figure, the same parts as those in FIG. 2 are denoted by the same reference numerals. The backlight device 11 for liquid crystal includes
It comprises a backlight device main body 11, a discharge lamp 12, and a lighting circuit (not shown). Reference numeral 13 in the figure is a liquid crystal display unit.

<Regarding Backlight Device Main Body 11> The backlight device main body 11 includes a light guide 11a, a gutter-shaped reflector 11b, a back reflector 11c, a diffusion plate 11d1, and a light collector 11d2, and is housed in a case (not shown). .

The light guide 11a is composed of a transparent plate having a high refractive index such as a transparent acrylic resin. The gutter-shaped reflector 11b reflects light emitted from the discharge lamp 12 in a direction not directly incident on the light guide 11a, and reflects the light emitted from the light guide 11a.
And shields the light emitted from the discharge lamp 12 from leaking to a portion other than the light guide 11a. The back reflector 11c reflects light emitted from the back of the light guide 11a and emits the light from the front of the light guide 11a. In this case, the reflectance of the back reflector 11c can be partially controlled so that light is emitted from the entire surface as uniformly as possible.
The diffusion plate 11d1 is provided on the front surface of the light guide 11a,
Light emitted forward from the light guide 11a is diffused to make the luminance distribution as uniform as possible. The light collector 11d2 is the diffusion plate 11
The light emitted from d1 is condensed to increase the efficiency of incidence on the liquid crystal display unit 13.

<Discharge Lamp 12 and Lighting Circuit> The discharge lamp 12 and the lighting circuit have the structure shown in FIG.

<Regarding the Liquid Crystal Display 13> The liquid crystal display 1
Numeral 3 is arranged on the front surface of the backlight device, and is illuminated from the back surface by the backlight device main body, thereby performing a transmissive liquid crystal display.

[0080]

According to the first to third aspects of the present invention, the internal electrodes are sealed inside the elongated light-transmitting airtight container, the discharge medium mainly composed of a rare gas is sealed, and the heat conductivity is reduced. A conductive metal wire of 100 W / m · K (0 ° C.) or more is wound in a coil shape and almost contacts the outer peripheral surface of the light-transmitting airtight container and extends in the longitudinal direction. By having an external electrode that causes a discharge during, heat conduction of the external electrode is good and heat radiation is promoted,
Since the temperature rise of the external electrode and the light-transmitting airtight container is reduced, even if the light-transmitting insulating coating is disposed outside the external electrode, the heat deterioration is reduced, and the temperature rise of the light-transmitting airtight container is reduced. It is possible to provide a discharge lamp having improved reliability in combination with the reduction of the discharge lamp.

According to the second aspect of the present invention, it is possible to provide a discharge lamp which is easy to carry out, since the external electrode is made of a conductive metal containing at least one of the group consisting of copper, aluminum, tungsten and molybdenum. it can.

According to the third aspect of the present invention, since the external electrode is formed of a surface-treated conductive metal wire, the surface of the conductive metal is modified and the durability of the external electrode is improved. A discharge lamp can be provided.

According to the fourth aspect of the present invention, the lighting device main body,
The provision of the discharge lamp and the lighting circuit according to the first to third aspects makes it possible to provide a lighting device having the effects of the first to third aspects.

[Brief description of the drawings]

FIG. 1 is a front view showing a first embodiment of a discharge lamp of the present invention.

FIG. 2 is a front sectional view, a side sectional view, and a circuit diagram showing a lighting circuit.

FIG. 3 is a front view showing a second embodiment of the discharge lamp of the present invention.

FIG. 4 is a front sectional view and a circuit diagram showing a lighting circuit.

FIG. 5 is a front view showing a third embodiment of the discharge lamp of the present invention.

FIG. 6 is a front sectional view, a side sectional view, and a circuit diagram showing a lighting circuit.

FIG. 7 is a cross-sectional view showing a liquid crystal backlight device as one embodiment of the lighting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Translucent airtight container 1a ... Slender cylindrical part 1b ... 1st end part 1c ... 2nd end part 1d ... Discharge space 2 ... Introductory line 3 ... Internal electrode 4 ... Lead wire 5 ... Phosphor layer 6 external electrode 6a winding start part 6b connection part 7 translucent insulating coating 8 lighting circuit

Claims (4)

[Claims] 1. An elongated light-transmitting airtight container; an internal electrode sealed in the light-transmitting airtight container; a discharge medium mainly composed of a rare gas sealed in the light-transmitting airtight container; Rate 1
A conductive metal wire of at least 00 W / m · K (0 ° C.) is wound in a coil shape to substantially contact the outer peripheral surface of the light-transmitting hermetic container and extend in the longitudinal direction. An external electrode for causing a discharge between the discharge lamp and the discharge lamp. 2. The discharge lamp according to claim 1, wherein the external electrode is made of a conductive metal containing at least one of the group consisting of copper, aluminum, tungsten and molybdenum. 3. The discharge lamp according to claim 1, wherein the external electrode has a surface treated with a conductive metal wire. 4. A lighting device body; and a discharge lamp according to claim 1 disposed on the lighting device body;
A lighting circuit for lighting a discharge lamp;