JP2001102004A - Inert gas discharge lamp and the lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inert gas discharge lamp that may improve the start-up properties thereof with minimizing deterioration during the lifetime of the lamp. SOLUTION: The discharge lamp comprises an elongated translucent discharge vessel 1; a discharge medium consisting essentially of inert gas including xenon and sealed in the discharge vessel 1; a luminescent material layer 3 disposed on the inner side of the discharge vessel 1; a pair of electrodes 5A, 5B disposed at outer surface of the discharge vessel with each electrode facing along the longitudinal direction of the vessel and having electric feeders 5c at one end of each electrode; an electron radiation layer 9 composed of an initial electron radiating material and a secondary electron radiating material and formed into a thin film so as to be exposed in the discharge space at inner surface of the vessel adjacent to the feeders 5c of the electrodes 5A, 5B; and a light guide opening 8 formed on the discharge vessel and located between two electrodes. With the electron radiation layer 9 formed at the inner surface of the vessel near the electric feeder, it may effectively improve the start-up properties of the lamp in the dark state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare gas discharge lamp in which electrodes are provided on the outer surface of a light-transmitting discharge vessel in which a rare gas such as xenon is sealed.

[0002]

2. Description of the Related Art As a light source for image reading such as an image reading apparatus, there is known a rare gas discharge lamp in which a pair of external electrodes are arranged to face each other along the longitudinal direction of an elongated translucent discharge vessel. I have.

[0003] Unlike a low-pressure mercury vapor discharge lamp, the rare gas discharge lamp rarely changes its light output due to a change in temperature and emits light with relatively high luminance. Therefore, its use in industrial equipment and the like tends to expand. It is in.

[0004] However, in this rare gas discharge lamp, since no electrodes are provided in the discharge space, it is difficult to obtain initial electrons at the time of starting. In particular, when mounted on the backlight of a liquid crystal display panel and used, there is no problem if it is used in a state where external light reaches the lamp, but it takes time to start in the so-called dark state where external light does not reach There is a problem.

As means for improving the dark start characteristics,
The techniques described in JP-A-4-284348 (Prior Art 1) and JP-A-8-329903 (Prior Art 2) are known.

In the prior art 1, initial electrons are obtained by mixing alumina or magnesia, which is an Exo electron emitting material, into a phosphor layer formed on the inner surface of the discharge vessel.

In the prior art 2, a conductive material such as aluminum, silver, graphite, tin oxide, indium oxide, barium, nickel or the like is applied to a region near the inner surface of the discharge vessel located between the electrodes. When a high-frequency voltage is applied, the rare gas in the vicinity of the conductive material is ionized to facilitate starting.

[0008]

In prior art 1, if alumina or magnesia, which is a non-light-emitting substance, is mixed into the phosphor layer, the light emission may decrease if the mixing amount is too large.

[0009] In the prior art 2, since the conductive substance may deteriorate during the life and deteriorate the conductivity, there is a possibility that stable starting characteristics cannot be ensured.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a rare gas discharge lamp capable of stably improving startability without deterioration during its life.

[0011]

According to the present invention, there is provided a rare gas discharge lamp according to the present invention, comprising: an elongated light-transmitting discharge vessel; a discharge medium containing xenon-containing rare gas as a main component sealed in the light-transmitting discharge vessel; A phosphor layer disposed on the inner surface side of the translucent discharge vessel;
A pair of external electrodes disposed on the outer surface of the light-transmitting discharge container so as to face each other along the longitudinal direction of the light-transmitting discharge container and each having a power supply portion at one end; an initial electron-emitting material and a secondary electron-emitting material An electron-emitting substance layer formed in a film shape so as to be exposed to the discharge space on the inner surface of the discharge vessel near the power supply portion of the pair of external electrodes; and a light-transmitting discharge vessel between the pair of external electrodes. And a light guide opening formed.

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

The translucent discharge vessel is made of soda lime glass,
Soft glass such as lead glass may be used, but hard glass such as borosilicate glass, semi-hard glass, quartz glass may be used if necessary, and materials other than glass such as light-transmitting ceramics may be used. Gender,
Any material that satisfies the fire resistance and workability at the operating temperature of the rare gas discharge lamp is acceptable.

The translucent discharge vessel may have any shape in a cross section perpendicular to the longitudinal direction. Generally, a cross-sectional shape is used, but an elliptical shape or a square shape can be used if necessary.

Further, the inner diameter of the translucent discharge vessel is about 13
mm or less is suitable, but is generally not particularly limited.

Further, that the light-transmitting discharge vessel is elongate means that the diameter is at least twice the diameter of the discharge vessel.
It can be set to any length required by the lighting device. However, the present invention has a relatively long pipe length of 180 to 5 mm.
It is particularly effective in a rare gas discharge lamp of 00 mm.

The discharge medium is mainly composed of a rare gas containing xenon, and xenon functions to excite the phosphor with ultraviolet rays having a wavelength of 172 nm generated by the low-pressure discharge to generate visible light. If necessary, in addition to xenon as a rare gas, krypton, neon, argon, etc. may be mixed and sealed to reduce the firing voltage due to the Penning effect. The flicker of brightness can be suppressed.

The pressure for filling the rare gas is not particularly limited, but is preferably 133 Pa to 26.6 kPa.

The phosphor layer functions to convert ultraviolet light generated by the low-pressure discharge of xenon into visible light or ultraviolet light of a different wavelength, as described above, and is directly or indirectly applied to the inner surface of the light-transmitting discharge vessel. It is arranged in.

The indirect means, for example, a reflective film mainly composed of particles of metal oxide having a high visible light reflectance, such as titanium oxide or alumina, having an average particle diameter of 50 to 100 nm on the inner surface of the translucent discharge vessel, and / or The method includes forming a protective layer of a metal oxide layer containing alumina fine particles as a main component, and disposing a phosphor layer on the inner surface side.

The phosphor is LaP for monochromatic reading.
O ₄ : A green-emitting phosphor such as Ce or Tb can be used. In addition, as a light source for a backlight device,
A phosphor that emits white light, such as a three-wavelength phosphor or a calcium halophosphate phosphor, can be freely selected.

Further, a non-fluorescent substance such as a binder or an electron-emitting particle can be mixed in the fluorescent layer in addition to the fluorescent substance.

Further, the position where the phosphor layer is disposed in the translucent discharge vessel will be described. That is, the phosphor layer should be disposed on at least the entire inner peripheral surface of the region surrounding the discharge space of the translucent discharge vessel, or disposed on other portions except for the portion facing the light guide opening. General. The latter is called aperture type. In order to form the phosphor layer except for the portion facing the light guide opening, the phosphor layer is formed on the entire inner surface of the light-transmitting discharge vessel, and then the phosphor layer in the portion facing the light guide opening is formed. The phosphor layer may be removed by peeling the layer using a scraper, or the phosphor layer may be formed by partial coating except for the portion facing the light guide opening from the beginning. In addition, the same process can be performed when a reflective film is formed, and can be removed simultaneously with the phosphor layer.

Further, a reflection film made of metal oxide fine particles is formed on the inner surface of the light-transmitting airtight container except for the light guide opening, and the phosphor layer is formed over the entire circumference including the light guide opening. This is called a reflection type. The present invention may have any of an aperture type and a reflection type.

The electron emitting material layer is formed on the inner surface of the container in the vicinity of the power supply portion of the pair of external electrodes, but may be formed on the phosphor layer in the same region. When forming the electron emitting material layer on the inner surface of the container, peel off the phosphor layer at
It is necessary to prevent the phosphor layer from being formed at the portion where the phosphor layer is to be formed.

It has been confirmed by an experiment that in the region where the electron emitting material layer is formed, the starting time is shortened as the electron emitting material layer is closer to the power supply portion of the pair of external electrodes. This is considered to be due to the fact that the electric field between the electrodes becomes larger as the position is closer to the power supply portion, and the initial electrons are strongly accelerated.

The electron-emitting material layer is formed by applying a mixture of an initial electron-emitting material and a secondary electron-emitting material in the form of a paste, or by applying a solution in which a powder of the mixed material is suspended in a solvent, followed by firing. Alternatively, it is formed into a film by a method such as drying.

The initial electron emitting material emits Exo electrons, and is composed of alumina (Al ₂ O ₃ ), lead oxide (Pb
O), zinc oxide (ZnO) and the like. In the case of alumina, α-alumina, which has a high Exo electron emission effect, is desirable. Note that magnesia (MgO) is also included in the substance that emits Exo electrons, but magnesia is preferably used as a secondary electron emitting substance in consideration of a combination with a secondary electron emitting substance. However, it is also possible to use magnesia as the initial electron emitting material and to combine it with a secondary electron emitting material other than magnesia.

The secondary electron emitting material is a material having a characteristic that more secondary electrons than the initial electrons hit by the collision of the initial electrons are ejected, and a material having a high secondary electron emission efficiency σ is selected. As the secondary electron emitting material used in the present invention, a mixture of magnesia, beryllium oxide (BeO) barium oxide and strontium oxide (BaO-S)
rO) and the like, but are not limited thereto.

The external electrodes are disposed on the outer surface of the light-transmitting discharge vessel such that a pair of the external electrodes are opposed to each other along the longitudinal direction of the light-transmitting discharge vessel. Therefore, a pair of gaps where no external electrodes are provided are formed around the translucent discharge vessel. These gaps function to ensure insulation between the pair of external electrodes, and at least one of them can be used as at least a part of a light guide opening described later.

The external electrode may be formed by attaching a thin plate of a conductive metal such as aluminum to the outer surface of the light-transmitting discharge vessel with an adhesive, or by applying a conductive paste, drying and firing. Good. Further, a conductive metal may be directly formed by deposition or the like.

The light guide opening is provided to guide light generated in the light-transmitting discharge vessel to the outside for use. If a light guide opening is formed along the longitudinal direction of the light-transmissive discharge vessel in order to utilize light distributed in the longitudinal direction of the elongated light-transmissive discharge vessel, the light-guiding opening is arranged around the light-transmissive discharge vessel. It is preferable to form it in at least one of a pair of gaps formed by a pair of external electrodes provided. However, if necessary, a slit may be formed along the longitudinal direction at the center of one or both external electrodes to form a light guide opening.

In order to insulate between the external electrodes, a transparent insulating coating can be formed outside the external electrodes. In this case, the transparent insulating coating is disposed in close contact with and surrounding the translucent discharge vessel and the pair of external electrodes. Therefore, the light guide opening and the gap on the opposite side are also covered together. For this reason, the light led out of the light-guiding light-transmitting portion passes through the transparent insulating coating and is taken out of the rare gas discharge lamp.

Further, the transparent insulating coating can be formed by dipping and solidifying a translucent discharge vessel provided with external electrodes in transparent silicone. Of course, it is desirable to connect the lead wires for supplying power to the external electrodes in advance.

Further, if necessary, for a backlight device or the like, the transparent insulating coating can be covered with a transparent heat-shrinkable tube. As the transparent heat-shrinkable tube, a heat-shrinkable tube made of a material having relatively excellent heat resistance such as a transparent fluororesin is preferable.

Further, when it is not necessary to leak light from the gap on the opposite side of the light guide opening, a light-shielding film or a metallic reflecting film may be added to the above-mentioned reflecting film or separately from the reflecting film. It can be formed on the outside.

The rare gas discharge lamp starts discharging when a high voltage is applied between a pair of electrodes, and is turned on. Further, the rare gas discharge lamp has an electron emitting material layer formed on the inner surface of the discharge vessel near the power supply portion of the pair of external electrodes so as to be exposed to the discharge space even in a dark state where external light does not reach the lamp. As a result, Exo electrons are emitted as initial electrons from the initial electron emitting material, and the initial electrons are accelerated by the high voltage applied between the pair of electrodes, so that many secondary electrons are emitted from the secondary electron emitting material. As a result, the discharge can be started more reliably.

According to the rare gas discharge lamp of the first aspect, the electron emitting material layer is formed on the inner surface of the discharge vessel near the power supply portion of the pair of external electrodes so as to be exposed to the discharge space.
Startability in a dark state can be improved.

A rare gas discharge lamp according to a second aspect of the present invention is an elongated translucent discharge vessel; a discharge medium mainly composed of a rare gas containing xenon sealed in the translucent discharge vessel; A phosphor layer disposed on the inner surface side; and a pair of external electrodes each having a power supply portion on one end side disposed on the outer surface of the translucent discharge container so as to face the longitudinal direction of the translucent discharge container. And; on the inner surface of the discharge vessel near the power supply portion of the pair of external electrodes, the initial electron emitting material is divided on one electrode side, and the secondary electron emitting material is separated on the other electrode side so as to be exposed to the discharge space. And a light-guiding opening formed in the translucent discharge vessel between the pair of external electrodes.

According to the rare gas discharge lamps of the first and second aspects, the electron emitting material layer is formed on the inner surface of the discharge vessel near the power supply portion of the pair of external electrodes so as to be exposed to the discharge space. Starting performance can be improved.

According to the first aspect, since the electron emitting material layer is formed by mixing the initial electron emitting material and the secondary electron emitting material to form a film, the electron emitting material layer can be formed relatively easily. be able to.

Further, according to the second aspect, the electron emitting material layer is formed in a film shape by dividing the initial electron emitting material on one electrode side and the secondary electron emitting material on the other electrode side. In addition, the film area and the film structure according to the electron emission characteristics of each substance can be formed independently.

According to a third aspect of the present invention, in the rare gas discharge lamp according to the second aspect, one of the electrodes is connected to a power supply section on the negative electrode side, and the other electrode is connected to a power supply section on the positive electrode side.

According to the rare gas discharge lamp of the third aspect, since the electrode on the side from which the initial electrons are emitted is the negative electrode, the initial electrons are accelerated and collide with the secondary electron emitting material side, and are more efficiently used. Secondary electrons can be emitted to improve startability.

When the lamp is lit with one electrode on the negative electrode side and the other electrode on the positive electrode side, the discharge lamp is lit by DC discharge. However, the polarity is fixed only at the start, and the AC lamp is lit after the start. Alternatively, a discharge lamp may be connected to a lighting device that can be switched to another.

According to a fourth aspect, in the rare gas discharge lamp according to any one of the first to third aspects, the initial electron emitting material is α-alumina and the secondary electron emitting material is magnesia.

According to the rare gas discharge lamp of the fourth aspect, the electron emitting material layer can be formed of a material that is industrially inexpensive and easy to handle.

A lighting device according to a fifth aspect includes a lighting device main body;
A rare gas discharge lamp according to any one of claims 1 to 4, which is disposed in the lighting device body.

In the present invention, the “illumination device” is a broad concept applicable to all devices that use light generated by a rare gas discharge lamp for some purpose. For example, it is applicable to an image reading device, a backlight device such as a liquid crystal device, a lighting fixture, a signal light device, and the like.

It is assumed that the illumination device includes, for example, OA equipment such as a copying machine, a facsimile, and a scanner, and information processing equipment such as a personal computer, which incorporate the image reading device and the backlight device.

The “illumination device main body” means the remaining portion of the illumination device excluding the rare gas discharge lamp.

A fifth aspect of the present invention provides an illuminating device provided with a rare gas discharge lamp having the function of any one of the first to fourth aspects.

[0053]

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

FIG. 1 shows a first example of the rare gas discharge lamp of the present invention.
It is a partially notched front view which shows embodiment. FIG. 2 is an enlarged cross-sectional view of the same. FIG. 3 is a partially enlarged cross-sectional view of the cross section taken along the line III-III of FIG.

In each of the figures, 1 is a translucent discharge vessel, 2 is a reflective film, 3 is a phosphor layer, 4 is an adhesive layer, 5A and 5B are a pair of external electrodes, and 5c and 5c are power supply parts as power supply parts. Terminal,
6 is a transparent silicone film, 7 is a transparent heat-shrinkable tube,
8 is a light guide opening, and 9 is an electron emitting material layer. 1 and 3, the reflective film 2, the adhesive layer 4, the transparent silicone film 6, the transparent heat-shrinkable tube 7
Is omitted.

The translucent discharge vessel 1 is made of an elongated transparent soft glass bulb having an outer diameter of 9.8 mm, a wall thickness of 0.55 mm, and a total length of 355 mm, both ends of which are sealed. ing. In addition, 1a is an exhaust chip, which is formed by closing an exhaust pipe provided at one end of the translucent discharge vessel 1, and evacuating the inside of the translucent discharge vessel 1 through the exhaust pipe, such as xenon. Is sealed after sealing.

The reflection film 2 has an average particle size of 50 to 100 n.
It is formed on the inner surface of the translucent discharge vessel 1 except for the portion facing the light guide opening 8, with the main component being titanium oxide particles of m.

The phosphor layer 3 is made of LaPO ₄ : C which emits green light.
The e-fluorescent material is formed on the inner surface of the translucent discharge vessel 1 except for the portion facing the light guide opening 8 except for the remaining portion.

Each of the pair of external electrodes 5A, 5B is made of an elongated aluminum foil having a total length of 350 mm, and has power supply terminals 5c, 5c connected to one end in the longitudinal direction by soldering.

Further, the pair of external electrodes 5A and 5B are separated and opposed to each other via the adhesive layers 4 and 4 so as to extend along the longitudinal direction of the translucent discharge vessel 1. And is disposed on the outer surface of the translucent discharge vessel 1.

The transparent silicone film 6 comprises an external electrode 5A,
The rare gas discharge lamp is coated from above 5B, but is applied by dip.

The transparent heat-shrinkable tube 7 is made of a transparent fluororesin, and covers the rare gas discharge lamp from above the transparent silicone film 6.

The light guide opening 8 is defined by the external electrodes 5A and 5B in the longitudinal direction of the translucent discharge vessel 1, and has a width of 6 mm.

The external electrodes 5 A, 5 A on the opposite side of the light guide opening 8
The interval between B is about 3 mm.

The electron emitting material layer 9 is provided with feed terminals 5c, 5c
The length of the container 1 in the longitudinal direction is about 5 mm on the inner surface of the light transmitting discharge container 1 in the vicinity. The electron emitting material layer 9 is formed by coating on a region where a part of the phosphor layer 3 is peeled off.

The electron emitting material layer 9 is formed so that the initial electron emitting material layer 9a is located on one electrode 5A side and the secondary electron emitting material layer 9b is located on the other electrode 5B side. The electrode 5A is connected to a lighting device (not shown) such that the power supply terminal 5c side of the one electrode 5A has a negative electrode side, and the other electrode 5B has a positive electrode side of the power supply terminal 5c side. As described above, since the electrode 5A on the side of the initial electron emitting material layer 9a from which the initial electrons are emitted is a negative electrode, the initial electrons are accelerated and collide with the secondary electron emitting material layer 9b side, and the secondary electrons are more efficiently emitted. Electrons can be emitted to improve startability.

According to the rare gas discharge lamp of this embodiment,
The electron emitting material layer 9 is formed on the inner surface of the discharge vessel 1 near the power supply terminals 5c, 5c of the pair of external electrodes 5A, 5B so as to be exposed to the discharge space.
The initial voltage and the secondary electron can be efficiently generated by using the high voltage applied to the substrate, and the discharge can be started.
Therefore, startability in a dark state can be improved.

In the above embodiment, the electron emitting material layer 9 is
Although formed so that the initial electron emitting material and the secondary electron emitting material are separated, magnesium oxide (Mg)
O) and aluminum oxide (α-Al ₂ O ₃ ) mixed at a ratio of about 1: 1 and the length of the container 1 in the longitudinal direction is about 5 mm.
It may be formed by coating with a width of. By applying a mixture of the initial electron emitting material and the secondary electron emitting material in this manner, the electron emitting material layer 9 can be easily formed.

Alternatively, each of MgO and α-Al ₂ O ₃ may be applied alone and alternately several times in a ring shape. Further, MgO and α-Al ₂ O ₃ may be independently applied alternately in a lattice pattern or a staggered pattern.

FIG. 4 is a conceptual sectional view showing an image reading device as a second embodiment of the illumination device of the present invention. In the figure, 11 is a rare gas discharge lamp, 12 is a light receiving means,
13 is a signal processing means, 14 is a document placing surface, 15 is a reflection plate, and 16 is a case.

The rare gas discharge lamp 11 shown in FIG. 1 is used. Then, the light emitted from the light guide opening of the rare gas discharge lamp 11 is applied to an original (not shown) via the original mounting surface 14.

The light receiving means 12 is arranged to receive the reflected light from the document surface. The signal processing means 13 processes the output signal of the light receiving means 12 to form an image signal.
The document placing surface 14 is made of transparent glass, on which the document is placed. The reflecting plate 15 directs the light emitted from the rare gas discharge lamp 11 to the document placing surface 14. Case 1
Reference numeral 5 stores the above components.

Thus, the rare gas discharge lamp 11 and the light receiving means 12 and the document placing surface 14 relatively scan each other. That is, as one or both of them move in the opposite direction, the light receiving means 12 sequentially receives the reflected light from the document surface in a direction perpendicular to the moving direction. The image reading apparatus according to the present embodiment is applicable to OA equipment such as a copying machine, an image scanner, and a facsimile.

[0074]

According to the rare gas discharge lamp of the first and second aspects, the electron emitting material layer is formed on the inner surface of the discharge vessel near the power supply portion of the pair of external electrodes so as to be exposed to the discharge space. Startability in a dark state can be improved.

According to the rare gas discharge lamp of the third aspect, since the electrode on the side from which the initial electrons are emitted is the negative electrode, the initial electrons are accelerated and collided with the secondary electron emitting material side, and are more efficiently used. Secondary electrons can be emitted to improve startability.

According to the rare gas discharge lamp of the fourth aspect, the electron emitting material layer can be formed of a material that is industrially inexpensive and easy to handle.

According to a fifth aspect, it is possible to provide an illuminating device provided with a rare gas discharge lamp having the effect of any one of the first to fourth aspects.

[Brief description of the drawings]

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

FIG. 2 is an enlarged cross-sectional view of FIG.

FIG. 3 is a partially enlarged cross-sectional view of the cross section taken along line III-III of FIG.

FIG. 4 is a conceptual cross-sectional view illustrating an image reading device as a second embodiment of the illumination device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transparent discharge container, 3 ... Phosphor layer, 5A, 5B ... A pair of external electrodes, 5c, 5c ... Power supply terminal as a power supply part, 8
... Opening for light guide, 9) Electron emitting material layer.

Claims (5)

[Claims] 1. An elongated light-transmissive discharge vessel; a discharge medium mainly containing a rare gas containing xenon sealed in the light-transmissive discharge vessel; and a fluorescent light disposed on the inner surface side of the light-transmissive discharge vessel. A body layer; a pair of external electrodes, which are provided on the outer surface of the translucent discharge vessel so as to face each other along the longitudinal direction of the translucent discharge vessel and each have a power supply portion on one end side; An electron emitting material layer formed in a film shape so that a mixture of secondary electron emitting materials is exposed to the discharge space on the inner surface of the discharge vessel in the vicinity of the power supply portion of the pair of external electrodes; And a light guide opening formed in the non-discharge vessel. 2. An elongated light-transmissive discharge vessel; a discharge medium mainly containing a rare gas containing xenon sealed in the light-transmissive discharge vessel; and a fluorescent light disposed on the inner surface side of the light-transmissive discharge vessel. A body layer; a pair of external electrodes, which are provided on the outer surface of the light-transmitting discharge container so as to face each other along the longitudinal direction of the light-transmitting discharge container and each have a power supply portion on one end side; The inner surface of the discharge vessel in the vicinity of the part, the initial electron emitting material is separated on one electrode side, and the secondary electron emitting material is separated on the other electrode side. A rare gas discharge lamp comprising: a radiating substance layer; and a light guide opening formed in a translucent discharge vessel between a pair of external electrodes. 3. The rare gas discharge lamp according to claim 2, wherein one of the electrodes is connected to a power supply portion on a negative electrode side, and the other electrode is connected to a power supply portion on a positive electrode side. 4. The rare gas discharge lamp according to claim 1, wherein the initial electron-emitting material is α-alumina, and the secondary electron-emitting material is magnesia. 5. A lighting device comprising: a lighting device main body; and the rare gas discharge lamp according to claim 1 disposed on the lighting device main body.