JP2003059458A - Discharge lamp and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp for improving a symmetric property of a light distribution characteristic in the tube axis direction, and a lighting system using this discharge lamp. SOLUTION: This discharge lamp has a slender light transmissive airtight vessel 1 having an exhaust tip-off part 1b on one end, an initial electron emitting substance 6 arranged on the inside surface side of the other end, a discharge medium mainly composed of xenon, and at least a pair of electrodes 3 and 3 arranged on an outside surface of the light transmissive airtight vessel 1. One kind or plural kinds of material are selected from a group including zinc oxide, aluminum oxide, magnesium oxide, barium oxynitride, lead oxide, and beryllium oxide, and can be used as the initial electron emitting substance 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp having a discharge medium containing xenon as a main component and having an external electrode, and a lighting device using the discharge lamp.

[0002]

2. Description of the Related Art A discharge lamp containing a discharge medium containing xenon as a main component and utilizing a rare gas discharge does not use mercury, which has a large environmental load, and therefore has an effect on the environment when it is discarded. Is low, there is no temperature dependence on the ambient temperature, and the luminous flux rising characteristics are excellent.

On the other hand, although this kind of lamp has various advantages as described above, it has a problem that the light output is small. On the other hand, by arranging a pair of electrodes on the outer surface of the translucent airtight container so as to face each other with an aperture extending in the tube axis direction interposed therebetween, high brightness can be obtained on the front surface of the aperture. It is used as a light source for reading and sidelight type backlights. The aperture is formed by a region in which the phosphor layer is not formed in the longitudinal direction of the glass bulb.

Further, a discharge lamp having a discharge medium containing xenon as a main component and having an external electrode arranged on the outer surface of the transparent airtight container is provided at one end of an elongated transparent airtight container such as a glass bulb. The exhaust pipe is provided with an exhaust tip-off portion formed by sealing the thin tube, exhausting the inside of the thin tube through the thin tube, enclosing the discharge medium, and then heating and melting the thin tube to seal it. However, in this type of discharge lamp, since the electrodes are arranged on the outer surface of the transparent airtight container, there is no source of initial electrons inside the transparent airtight container, and therefore there is a delay in lighting in the dark. However, there is a problem of having a so-called dark characteristic. As the initial electron source, light from the outside, radiation from the earth,
Cosmic rays from the sky are possible. However, the former light is
Since it does not exist in the dark, and the absolute amount of the radiation of the middle and the cosmic rays of the latter is small, we cannot expect them from the initial electron source.

Therefore, in the prior art, an initial electron emitting substance such as zinc oxide or aluminum oxide is adhered to the inner end of the translucent airtight container as an initial electron supply source at the end of the tube on the exhaust tip off side. .

[0006]

However, in the case where the portion to which the initial electron emission material is deposited has a low light transmittance, there arises a problem that the light distribution characteristic in the tube axis direction becomes asymmetric. I found out that If the light distribution becomes asymmetric, when using the discharge lamp as the reading light source,
Since there is not enough space in the reading device, the size of the light source is limited with respect to the reading width.Therefore, if the light distribution characteristics become asymmetric, it may not be possible to read the edges of the document sufficiently. is there.

An object of the present invention is to provide a discharge lamp with improved symmetry of light distribution characteristics in the tube axis direction and a lighting device using the discharge lamp.

[0008]

According to another aspect of the present invention, there is provided a discharge lamp comprising: an elongated translucent airtight container having an exhaust tip-off portion at one end; and an inner surface side of the other end of the translucent airtight container. And a discharge medium containing xenon as a main component, which is enclosed in a transparent airtight container, and at least a pair of electrodes arranged on the outer surface of the transparent airtight container. It is characterized by that.

In the present invention and the following inventions, the definitions and technical meanings of terms are as follows unless otherwise specified.

<Translucent Airtight Container> The translucent airtight container seals both ends of a glass bulb or an opening formed at the base end of a glass bulb with a closed tip (for example, a T-shaped bulb). It is preferable to form it by the above method because it is the easiest to manufacture and the cost is low, but if necessary, it may be formed of a translucent ceramic or the like. As the glass, soft glass, semi-hard glass, hard glass, quartz glass or the like can be appropriately selected and used. The "translucency" of a translucent airtight container does not mean that the entire translucent airtight container is translucent, and at least let the light emitted with discharge be emitted to the outside. It suffices that the portion to be transparent to the light. Further, that the translucent airtight container is elongated means that it has a length that is at least twice the outer diameter of the discharge container.

If the light-transmitting hermetic container has an exhaust tip-off portion at one end and the other end is in a position opposite to the one end and the light distribution in the middle part is utilized, the light-transmitting airtight container is directly connected. The shape is not limited to a tubular shape, and if necessary, the middle may be a curved tubular shape. The exhaust tip-off portion is formed, for example, by glass-welding a thin tube to one end of a translucent airtight container, and heating and melting the thin tube to close it. The glass can be welded to one end of the translucent airtight container of the thin tube by any means, for example, a thin tube is inserted into the one end to perform pinch sealing, or a bead seal using a glass bead sealing the thin tube. By this, the thin tube can be glass-welded. Alternatively, one end of the glass tube may be molded by tubing to integrally form a thin tube.

Further, the other end of the transparent airtight container is sealed as it is. The sealing can be performed by a known means such as a pinch seal or a bead seal. Alternatively, a so-called T-shaped valve whose other end is closed in advance as described above may be used. The translucent airtight container may have any cross-sectional shape such as flat, square, or triangular.

<Regarding the Initial Electron Emitting Material> The initial electron emitting material is disposed on the inner surface side of the other end of the transparent airtight container, and the initial electron is stored in the transparent airtight container at the time of starting in the dark. To release. The “initial electron” means so-called exo-electron. The initial electron emitting substance is not limited to a specific substance as long as it is a substance having an initial electron emitting action. For example, one or more selected from the group of zinc oxide, aluminum oxide, magnesium oxide, barium oxynitride, lead oxide and beryllium oxide can be used.

The initial electron emitting material is disposed on the other end of the light-transmitting hermetic container, that is, on the inner surface side of the non-exhaust tip-off portion side. As a result, the initial electron emitting substance is not disposed on the inner surface side of one end of the translucent airtight container.

Further, the initial electron-emitting substance is preferably applied in a ring shape on the inner surface of the light-transmitting hermetic container in the form of a large number of fine particles gathered in a film form.

<Discharge Medium> The discharge medium contains xenon as a main component and emits ultraviolet rays due to discharge between the electrodes. One or more kinds of noble gases consisting of neon, argon, krypton, and helium can be optionally added. In addition to the rare gas, for example, Kr
A rare gas halide such as F or ArCl or a simple substance of halogen may be added. As halogen, iodine,
Bromine and chlorine can be used. Hundreds to 1 MPa
Discharge is possible as long as the element exists as vapor within a certain range.

<Regarding at least a pair of electrodes> At least a pair of electrodes are arranged on the outer surface of the translucent airtight container. The "at least a pair of electrodes" means
This means that a plurality of pairs of electrodes can be provided.
In this case, one of the electrodes can be shared. The electrode is disposed so as to substantially contact the outer surface of the translucent airtight container, and is preferably made of a conductive thin film body. As the conductive thin film, aluminum, silver, foil of a conductive metal such as copper,
A vapor deposition film of a conductive metal, a plating film, a coating film formed by screen-printing a conductive paste, an ITO film, a NESA film, or the like can be used. Although the thickness of the conductive thin film is not limited, it is generally about 10 to 200 μm, preferably about 30 to 100 μm in terms of contact with the outer surface of the transparent airtight container, electric resistance, and the like. Good results are obtained. When the electrodes are made of a conductive thin film, the external electrodes may be formed in a ribbon shape, or may be formed in a deformed shape such as a mesh shape or a wavy shape.

However, the electrode is not limited to the conductive thin film body, but may be a coil body made of a conductive wire, a mesh structure or the like, if necessary, and is almost in contact with the outer surface of the translucent airtight container. It can be arranged. In addition,
The electrode is “almost in contact with the outer surface of the light-transmitting airtight container”, which means that the entire electrode is directly on the outer surface of the light-transmitting airtight container or through a dielectric substance such as an adhesive. Indirect contact is desirable, but this is not an essential requirement, and generally means that the electrode may be in contact with the outer surface of the translucent airtight container. Also, in the case of a coil body, a pair of coils made of conductive wires are shifted in the axial direction of the semi-pitch translucent airtight container, and spirally wound in the same direction while being separated from each other on the outer peripheral surface of the translucent airtight container. It can be wound into a shape. In the case of the mesh structure, one or both of the electrodes having a required area spread can be adopted.

At least one pair of electrodes has a size extending in the longitudinal direction, that is, the axial direction of the light-transmitting hermetic container. Then, in the outer peripheral direction of the translucent airtight container, it is possible to arrange the electrodes in a required angular range after ensuring a required creeping insulation distance between the electrodes.

Further, when the pair of electrodes is composed of any one of the coil, the mesh structure and the transparent conductive film, light is transmitted through the electrodes or through the gap between the electrodes in these structures. Since it is led out to the outside, it is possible to impart a light distribution characteristic that spreads in the entire circumferential direction of the translucent airtight container. On the other hand, when the electrode is made of a metal foil, the metal foil is not substantially light-transmissive, and thus has a non-uniform light distribution characteristic in the axial direction. The latter configuration is suitable for aperture-type discharge lamps.

Furthermore, when the electrode is made of a metal foil, the metal foil is previously attached to one surface of a light-transmissive resin sheet, which will be described later, and the adhesive is applied to the outer surface of the light-transmissive airtight container. It can be arranged by sticking. However, the metal foil can be directly attached to the outer surface of the translucent airtight container. Further, the width of the electrode may be changed in the axial direction of the translucent airtight container.

Next, in order to bring the electrode into contact with the outer surface of the translucent airtight container, an adhesive is applied to the contact surface of the electrode in advance, and the electrode is attached to the translucent airtight container with the adhesive. it can. However, an adhesive may be applied to a portion of the translucent airtight container that is to be brought into contact with the electrode, and the electrode may be attached thereto. Further, without using a pressure-sensitive adhesive or an adhesive, the electrode may simply be brought into contact with the planned contact portion, and the light-transmissive resin sheet to which the pressure-sensitive adhesive is applied may be wrapped around the electrode over the entire circumference thereof. .

<Other Configurations> Although not essential to the present invention, the following configurations can be added as required, whereby the function of the discharge lamp is added and the performance is improved. .

1 Regarding the Phosphor Layer The phosphor layer is used in the case of converting the wavelength of the ultraviolet rays emitted by the discharge medium by the discharge into visible light. Then, it is arranged on the inner surface side of the translucent airtight container. Further, the phosphor layer may be arranged over the entire circumference on the inner surface side of the translucent airtight container, or may be arranged so as to form an aperture extending in a slit shape along the longitudinal direction. . Incidentally, "the inner surface side of the translucent airtight container" means that the phosphor layer is directly formed on the inner surface of the translucent airtight container and the indirect fluorescent light is applied to the inner surface of the translucent airtight container through a protective film. It is meant to include any of the modes for forming a body layer. What is an "aperture"?
In order to concentrate the radiation generated inside the transparent airtight container to the outside from the relevant portion, it means an optical opening for guiding light, which is formed in the transparent airtight container.

Next, as the phosphor, a single kind or a mixture of plural kinds of phosphors can be used. It is possible to use a white light emitting three-wavelength emitting phosphor obtained by mixing red, green and blue light emitting phosphors. However, if necessary, in order to obtain discharge lamps of R (red), G (green) and B (blue) emission colors as the discharge lamp, respective monochromatic phosphors may be used. It is also possible to obtain white light by additive color mixing by using one set or a plurality of sets of each monochromatic light emitting discharge lamp. The phosphor layer may have a single layer structure or a multilayer structure.
In the latter case, the type of phosphor may be different for each layer. Further, a third layer made of a substance other than a phosphor, such as a conductive layer, a discharge state improving layer mainly containing a metal oxide, may be interposed between the phosphor layers.

2. Regarding the reflective film, a reflective film can be provided between the phosphor layer and the inner surface of the translucent airtight container that faces the phosphor layer. As the constituent material of the reflective film, for example, fine particles such as TiO ₂ or MgO can be used. Prepare a dispersion of these materials and apply to the inner surface of the translucent airtight container except for the aperture part,
The reflection film can be formed by firing.

By forming a reflective film,
Visible light generated from the phosphor layer and directly transmitted through the translucent airtight container to be emitted to the outside can be reflected and led out from the aperture. Then, this makes it possible to further increase the brightness of the aperture.

3. About the translucent insulating coating, in order to mechanically protect the external electrode and to ensure the connection between the external electrode and the external lead wire, if necessary, in addition to improve the insulation property of the discharge lamp, A translucent insulating coating can be provided on the outside of the external electrode. The translucent insulating coating is preferably transparent. Further, the light-transmissive insulating coating may be heat-shrinkable or may be applied by dipping for the workability of arrangement. However, a translucent insulating sheet may be wrapped around.

4. About the lighting circuit Since the fluorescent lamp uses the dielectric barrier discharge, the lighting circuit is generally 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. It is possible to use a configuration in which the voltage is directly applied between the opposing electrodes without using an external current limiting impedance. The pulse voltage can be obtained, for example, by half-wave rectifying a high frequency AC voltage having a rectangular wave or a sine wave. Further, the lighting circuit can be configured by an inverter.

<Regarding Operation of the Present Invention> In the present invention, the initial electron emitting material is disposed on the inner surface side of the other end of the translucent airtight container which is the non-exhaust tip-off part side. The light distribution characteristics in the tube axis direction are symmetrical. That is, on one end side of the translucent airtight container, since the exhaust tip-off portion and the non-light emitting portion such as the sealing portion associated therewith are present, the light distribution is reduced. Further, on the other end side, since the initial electron emitting substance is arranged, the light distribution is lowered. As a result, the light distribution deterioration at both ends of the translucent airtight container is balanced, so that the symmetry of the light distribution characteristics is improved. It should be noted that the distribution of light distribution on both ends of the translucent airtight container is less likely to decrease, and is 90% relative to the relative illuminance at the center.
% Can be maintained.

Of course, even if at least a pair of electrodes is provided on the outer surface of the transparent airtight container, since the initial electron emitting substance is provided inside the transparent airtight container, the same as in the prior art. At the time of start-up, required initial electrons are emitted and supplied from the initial electron emission material into the transparent airtight container. Therefore, the lighting delay does not occur even in the dark.

The discharge lamp according to the invention of claim 2 is the discharge lamp of claim 1.
The discharge lamp described is characterized in that the initial electron emission material is deposited in a range of 1 to 5 mm with respect to the axial direction of the translucent airtight container.

The present invention defines a preferable range of the amount of the initial electron emitting material to be provided. That is, within the above range, a sufficient amount of initial electrons are supplied for a long period of time, and the light distribution is not excessively reduced, so that the symmetry of the light distribution characteristic in the tube axis direction becomes good. On the other hand, when the initial electron emitting substance is less than 1 mm, the initial electron emitting substance is reduced and it becomes difficult to obtain a sufficient amount of initial electrons for a long period of time. On the other hand, if it exceeds 5 mm, the distribution of light distribution on the other end side of the translucent airtight container is excessively reduced, and it becomes difficult to obtain symmetry of the light distribution characteristic in the tube axis direction.

An illumination device according to a third aspect of the present invention comprises: an illumination device main body; a discharge lamp according to claim 1 or 2 disposed in the illumination device main body; and a lighting circuit for lighting the discharge lamp. It is characterized by being.

In the present invention, the "illuminating device" is a broad concept including all devices that utilize the light emission of a fluorescent lamp, and for example, a reading device and a scanner, a copying machine, a facsimile machine or a compound machine including them. And a backlight unit, a liquid crystal display device including the backlight unit, and a device incorporating the liquid crystal display device. A device incorporating a liquid crystal display device is, for example, a device incorporating a liquid crystal display device such as a personal computer, a navigation device, a personal digital assistant, a liquid crystal television receiver,
In addition, it is an instrument panel lighting device for a mobile body such as an automobile, a lighting device for decoration, an indicator light, and a marker light.

The "illuminating device main body" means the remaining portion of the illuminating device excluding the discharge lamp and the lighting circuit.

[0037]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 show an embodiment of the discharge lamp according to the present invention. FIG. 1 is a front view and FIG. 2 is a line II-II in FIG.
2 is an enlarged cross-sectional view taken along the line ', FIG. 3 is an enlarged cross-sectional view taken along the line III-III' of FIG. 1, and FIG. is there.

In each figure, the discharge lamp comprises a transparent airtight container 1, an initial electron emission material 6, a phosphor layer 2, a pair of electrodes 3, 3, an aperture 4 and a transparent resin sheet 5. .

The light-transmitting airtight container 1 is formed by sealing both ends of a light-transmitting tube 1a made of glass having an outer diameter of 8 mm and a lamp length of 366 mm which is elongated and hermetically sealed at both ends. A discharge space 1c is formed inside,
In addition, the exhaust tip-off portion 1b and the sealing portion 1d are provided at one end, and xenon is sealed inside as a discharge medium. The exhaust tip-off portion 1b is formed by exhausting the inside of the translucent airtight container 1 via a thin tube, enclosing a discharge medium therein, and then heating and melting the thin tube to close it. The sealing portion 1d is formed by pinching one end of the transparent airtight container 1 and is interposed between the exhaust tip-off portion 1b and the discharge space 1c inside the transparent airtight container 1.

The phosphor layer 2 is formed on the inner surface of the translucent airtight container 1 except for the slit-shaped apertures 4 in the longitudinal direction.

As shown in FIGS. 1 and 3, the initial electron emitting material 6 is made of a film-shaped aggregate of aluminum oxide fine particles, and the inner surface of the other end of the translucent airtight container 1 on the non-exhaust tip-off side. In addition, the transparent airtight container 1 is coated over the entire circumference in a range of a width of 3 mm in the tube axis direction. The initial electron emitting substance 6 is provided by preparing a dispersion liquid containing aluminum oxide fine particles, a dispersion medium and a solvent, applying the dispersion liquid to the inner surface of a required portion of the translucent airtight container, and firing it. be able to. The initial electron emission material 6 is formed on the phosphor layer 2.

Each of the pair of electrodes 3, 3 is made of aluminum foil, and meanders and has a wavy shape as shown in FIG. 4, but as a whole is simplified as shown in FIGS. , Are arranged by adhering to the outer surface of the translucent airtight container 1 so as to be spaced apart from each other and parallel to each other. The external electrode 2 is attached to one surface of an adhesive translucent resin sheet 5 which will be described later in advance, and the translucent resin sheet 5 is wrapped around the outer periphery of the translucent airtight container 1 to be adhered. It is arranged at a predetermined position on the outer surface of the light tight container 1.

The electrode 3 is composed of an electrode main portion 3a, a terminal connecting portion 3b and a terminal 3c. The electrode main portion 3a is configured to have a corrugated shape and extend over most of the length of the translucent airtight container 1. The terminal connecting portion 3b is
It is arranged so as to be connected to one end of the electrode main portion 3a, and is formed in a rectangular shape so that the contact area with the terminal 3c is increased.
The terminal 3c is adhered to the terminal connecting portion 3b with a conductive adhesive and protrudes from the translucent resin sheet 5 to the outside.

The aperture 4 has an angle of 65 ° and is formed by a portion along the longitudinal direction of the translucent airtight container 1 in which the phosphor layer 2 is not formed in a slit shape. Therefore, the portion of the aperture 4 of the transparent airtight container 1 is
Through the glass bulb 1a, the inside of the translucent airtight container 1 looks transparent.

The transparent resin sheet 5 is made of PET,
The length of substantially the entire length of the translucent airtight container 1, and
It has such a width that it covers the entire circumference of the translucent airtight container 1 including the top of the aperture 4 in the circumferential direction. As described above, the pair of electrodes 3 and 3 are attached to one surface at a predetermined interval, and an acrylic adhesive is further applied onto the electrode 3 and the electrodes are attached to the outer surface of the translucent airtight container 1. As a result, the pair of electrodes 3, 3 are arranged on both sides of the aperture 4 with the aperture 4 interposed therebetween, and the translucent resin sheet 5 is also provided on the aperture 4.
Is attached.

FIG. 5 is a graph showing the light distribution characteristics of one embodiment of the discharge lamp of the present invention together with that of the comparative example. In the figure, the horizontal axis shows the position of the discharge lamp in the axial direction, and the vertical axis shows the relative illuminance "%" when the lamp center is 100%. Further, in the figure, the solid line shows the light distribution characteristics of the present invention, and the dotted line shows the light distribution characteristics of the comparative example.
The comparative example is a discharge lamp having the same configuration as that of the present embodiment except that the initial electron emitting substance is disposed at the end of the discharge space 1c on the exhaust tip-off portion 1b side.

As can be seen from the figure, according to the present invention, 90% relative illuminance can be obtained at the end positions of 155 mm to the left and right from the lamp center, and light distribution characteristics excellent in symmetry can be obtained. On the other hand, in the comparative example, the other end on the right side in the figure is 92%,
One end on the left side is 88%, which shows that the symmetry is inferior.

FIG. 6 is a conceptual sectional view showing an image reading apparatus as an embodiment of the illuminating device of the present invention. In the figure, 11 is an image reading optical system, 12 is a signal processing device, and 1
3 is a document mounting surface, 14 is a lighting circuit, and 15 is a case.

The image reading optical system 11 in this embodiment is a fluorescent lamp 11a, a mirror 11b, and an integrated lens 11.
c and the charge coupled device 11d are the main constituent elements. Although not shown, the fluorescent lamp, the self-phonic lens, and the charge-coupled device may be the main components. The fluorescent lamp 11a has the structure shown in FIGS. Then, the light emitted from the aperture is applied to a document (not shown) through the document placement surface 13. The light reflected from the document is arranged to be reflected by the mirror 11b in a predetermined direction, condensed by the integrated lens 11c, and received by the charge coupled device 11d, that is, the CCD.

The signal processing device 12 processes the output signal of the light receiving means 11b to form an image signal.

The lighting circuit 14 lights the fluorescent lamp 11a at a high frequency.

The case 15 accommodates each of the above components inside.

Then, the image reading optical system 11 and the document placing surface 13 are relatively scanned. That is, in the process in which one or both of them are driven by a driving mechanism (not shown) to move in the opposite direction, the charge-coupled device 11d sequentially receives light reflected from the document surface in a direction perpendicular to the moving direction. go. The image reading apparatus of this embodiment is applicable to OA equipment such as a copying machine, an image scanner and a facsimile.

[0055]

According to the first aspect of the present invention, an elongated light-transmitting airtight container having an exhaust tip-off portion at one end, an initial electron emitting substance disposed on the inner surface side of the other end, and xenon are mainly contained. Discharge lamp having improved symmetry of light distribution characteristics in the tube axis direction by providing a discharge medium as a component and at least a pair of electrodes arranged on the outer surface of a translucent airtight container. can do.

According to the second aspect of the invention, in addition, the initial electron emitting material is 1 to 5 mm in the axial direction of the light-transmitting hermetic container.
By being deposited in this range, it is possible to provide a discharge lamp that has a good initial electron supply action for a long period of time and that can easily maintain the symmetry of the light distribution characteristics.

According to a third aspect of the present invention, there is provided a lighting device main body, the discharge lamp according to the first or second aspect provided in the lighting device main body, and a lighting circuit for lighting the discharge lamp. Thus, it is possible to provide a lighting device having the effects of the first and second aspects.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view taken along the line II-II ′ of FIG.

FIG. 3 is an enlarged cross-sectional view taken along the line III-III ′ of FIG.

FIG. 4 is a development view of an electrode and a translucent resin sheet according to an embodiment of the discharge lamp of the present invention viewed from the external electrode side.

FIG. 5 is a graph showing the light distribution characteristics of an embodiment of the discharge lamp of the present invention together with that of a comparative example.

FIG. 6 is a conceptual cross-sectional view showing an image reading device as an embodiment of a lighting device of the present invention.

[Explanation of symbols]

1 ... Translucent airtight container 1a ... Translucent tube 1b ... Exhaust tip off section 1d ... Sealing part 3 ... Electrode 3c ... Terminal 4 ... Aperture 6 ... Initial electron emission material

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ryuji Tsuchiya             1 Hariso at 5-2 Asahi-cho, Imabari-shi, Ehime             Within Toshiba Lighting Co., Ltd. (72) Inventor Hiroaki Maruyama             1 Hariso at 5-2 Asahi-cho, Imabari-shi, Ehime             Within Toshiba Lighting Co., Ltd.

Claims (3)

[Claims] 1. An elongated translucent airtight container having an exhaust tip-off portion at one end; an initial electron emitting substance disposed on the inner surface side of the other end of the translucent airtight container; A discharge lamp comprising: a discharge medium containing xenon as a main component sealed inside; and at least a pair of electrodes arranged on an outer surface of a translucent airtight container. 2. The discharge lamp according to claim 1, wherein the initial electron emission material is deposited in a range of 1 to 5 mm with respect to the axial direction of the translucent airtight container. 3. A lighting device, comprising: a lighting device main body; a discharge lamp according to claim 1 or 2 disposed in the lighting device main body; and a lighting circuit for lighting the discharge lamp. .