JP2982888B2 - Discharge lamp electrode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a portable personal computer.
The present invention relates to an electrode of a backlight discharge lamp for a liquid crystal display device used for a computer or a word processor.

[0002]

2. Description of the Related Art With the rapid spread of personal computers in recent years, small-sized personal computers or word processors suitable for carrying are rapidly spreading. Personal computers called notebooks, which are small in size, are popular because of their small size and light weight and low cost.

In many cases, a liquid crystal display device is used as a display device in the notebook personal computer. However, since the liquid crystal display device is not a light emitting display device, a light source is required to view display contents. The simplest light source uses an external light source. However, an internal light source is necessary because a sufficient amount of light is required for use in a place where the external light source is insufficient or for color display. The internal light source is called a backlight light source for emitting light from the back of the liquid crystal display device, and is required to be a surface light source for displaying the entire liquid crystal display surface. Therefore, at present, a fluorescent discharge lamp combined with an electroluminescent (Electro Luminescent = EL) element or a light guide plate is used as a backlight light source.

FIG. 1 shows the structure of a backlight light source 1 using a fluorescent discharge lamp. In this figure, reference numeral 2 denotes a light guide plate made of a light-transmissive material such as glass or acrylic resin, and its surface is formed with irregularities for radiating light incident from a side surface of the plate in a plane direction. Fluorescent discharge lamps 3 and 3 are attached to both sides of the light guide plate 2 as light sources for allowing light to enter the light guide plate 2.

FIG. 2A is a sectional view of a conventional fluorescent discharge lamp used for a backlight light source, and FIG. 2B is an enlarged sectional view of a circle b at the end of the tube. In this figure, reference numeral 4 denotes an elongated cylindrical hermetically sealed glass tube container having a fluorescent substance applied to its inner wall, and lead wires 5 and 5 are provided at left and right ends of the glass tube container 4, respectively. At the tip of the lead wire 5, a tungsten filament 6, 6 coated with an electron emitting material such as barium oxide (BaO) is attached, and a mercury dispenser 9 is disposed between the filament 6, 6 and the tube end. Have been.

In the case of a fluorescent discharge lamp, a low-pressure (about 1 Pa) mercury (Hg) gas is used as a discharge gas, and the filaments 6, 6 disposed opposite to each other in the glass tube are energized and heated. When applied, the mercury gas emits ultraviolet rays having a wavelength of 253.7 nm, and the ultraviolet rays are applied to a fluorescent material such as calcium halophosphate (3Ca ₃ (PO ₄ ) ₂ .CaFCl / Sb, Mn) applied to the inner wall of the glass tube. The light is converted into visible light by being irradiated.

In addition, an argon (Ar) gas having a pressure of about several hundred Pa is sealed in the discharge gas in order to facilitate ionization of the mercury gas to facilitate discharge (penning effect). To manufacture a fluorescent discharge lamp, an argon gas, which is a gas for starting discharge, is sealed, the end of the tube is closed and the entire tube is sealed, and then the mercury dispenser 9 is heated using a high-frequency induction heating device or the like. By discharging mercury vapor from the enclosed Ti ₃ Hg into the tube, the mercury gas is enclosed.

Conventionally, as a cathode of a fluorescent tube having such a configuration, BaO, SrO is added to a tungsten filament.
Alternatively, a hot cathode coated with an electron emitting material such as CaO is used. Since the hot cathode requires a preheating circuit, the apparatus cost is high, the power consumption is large, and the re-ignition voltage is high. In addition, mercury ions generated during the discharge are accelerated by the strong electric field on the front surface of the cathode and collide with the electrode, causing sputtering that scatters the electrode material, thereby shortening the life of the electrode and blackening the tube end near the electrode. There's a problem.

There is a strong demand for miniaturization and power saving for notebook personal computers in which a backlight light source using a fluorescent discharge lamp is frequently used, and therefore there is also a demand for power saving and thinning of the backlight light source. strong. However, since the filament as the hot cathode requires a certain size, the inner diameter of the glass tube cannot be reduced, and the outer diameter of the ordinary glass tube is about 8 mm.

To meet this demand, a cold cathode fluorescent lamp has been proposed. This cold cathode discharge lamp is shown in FIG.
In place of the filament and the mercury dispenser of the hot cathode discharge lamp shown in (1), a cold cathode serving also as a mercury dispenser is attached to the lead wire.

Since this cold cathode fluorescent lamp does not have a hot cathode unlike the hot cathode fluorescent lamp shown in FIG. 2, the power consumption is small and the life of the tube is long. Further, since no filament is used, the inner diameter of the glass tube can be reduced, and the outer diameter of the glass tube can be generally reduced to about 4 mm. Nickel metal is used as a material for the cold cathode. However, nickel metal emits a small amount of electrons, so that the luminance cannot be increased, and the discharge starting voltage is high.

On the other hand, a discharge lamp electrode using a ceramic obtained by converting a ceramic such as BaTiO ₃ into a semiconductor by a reduction treatment is described in US Pat. No. 2,686,274. Semiconductor porcelain is composed of mercury ions and argon (A
r), weak to ion bombardment of rare gas ions such as neon (Ne), xenon (Xe), and krypton (Kr). Sputtering is caused by ion bombardment to deteriorate electron emission characteristics.

In order to solve this problem, a ceramic semiconductor electrode material having a sputter-resistant layer formed on its surface and a method for producing the same are disclosed in US Pat. No. 4,808,883 (JP-A-62-291854) and JP-A-62-291854. Showa 55-4983
No. 3, JP-A-2-186527, JP-A-2-186527
186550 and JP-A-2-215039.

Also, a fluorescent discharge lamp cathode using these ceramic semiconductor electrode materials is disclosed in US Pat. No. 4,808,88.
No. 3 (JP-A-62-291854, JP-A-63-15551, JP-A-63-15552, JP-A-63-15553, JP-A-63-15
554), JP-A-2-186527, JP-A-2-186550, and JP-A-2-215039. These fluorescent discharge lamp cathodes are made of a ceramic semiconductor, and it is difficult to maintain a high temperature for discharge. In order to solve this problem, Japanese Patent Application Laid-Open No. 4-43546 discloses a fluorescent discharge lamp cathode in which a ceramic semiconductor is formed in a granular shape and housed in a heat-resistant ceramic container.

FIG. 3 is a sectional view of a tube end of the fluorescent discharge lamp. In this figure, 4 is a glass tube container, and 11 is an electrode cylinder. The glass tube container 4 is an elongate container having a cylindrical cross section. At both ends of the glass tube container 4, lead wires 5 and 5 made of heat-resistant metal are provided. A holding portion 10 for holding the electrode cylinder 11 is provided at the tip of the lead wire 5.
Numeral 0 is made of an elastic conductive material and is configured to elastically sandwich the outer periphery of the electrode cylinder 11. The mercury dispenser 14 is provided between the holding portion 10 and the lead wire 5 and the winding portion 1 is provided.
5 are formed and attached.

The electrode cylinder 11 is a closed-end cylindrical ceramic porcelain having a high melting point or good sputtering resistance, for example, a Ba (Zr, Ta) O ₃ -based semiconductor porcelain. Hollow portion 12 formed in cylinder 11
In this case, a bulk, granular or porous semiconductor porcelain 13 is housed. Electrode cylinder 11
As for the size of inside diameter 0.9mm, outside diameter 1.9mm, length 2.
3mm, inner diameter 1.6mm, outer diameter 2.6mm, length 2.3m
There are m. The applicant of the present invention has disclosed in Japanese Patent Application No. 5-56747 a 0.5 material as a material used for these semiconductor ceramics.
~ 1.5 moles of a first component selected from BaO, CaO or SrO, and 0.05-5.95 moles of ZrO ₂
Alternatively, a second component selected from TiO ₂ and 0.02
5 to 0.475 moles of _{V 2 O 5, Nb 2 O} 5, Ta 2 O 5, S
c ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ or 0.05 to 0.95 mol of HfO ₂ , CrO ₃ , Mo
A bulk, granular or porous discharge lamp electrode material comprising a third component selected from O ₃ and WO ₃ has been proposed.

In this ceramic cathode fluorescent discharge lamp, when the discharge is started by the discharge starting argon gas, the ionized gas generates plasma near the discharge lamp electrode, and the semiconductor ceramic 13 is locally heated by the plasma. The generation of the arc spot causes an arc discharge, and the low thermal conductivity of the semiconductor porcelain 13 maintains a stable high-temperature state and maintains a high-density arc discharge. Since this ceramic cathode fluorescent lamp does not have a filament, the power consumption is small, and there is no problem of a short life due to sputter loss of the electron-emitting substance and the like. In addition, since it is a hot cathode type, unlike a cold cathode type, a discharge starting voltage can be reduced and luminance can be increased.

FIG. 4 is an enlarged view of the structure of a ceramic electrode composed of an electrode cylinder and semiconductor porcelain. In this figure, a granular semiconductor porcelain 13 is housed in a hollow portion 12 formed in a bottomed cylindrical semiconductor porcelain cylinder 11 having one opening. This ceramic electrode is used for the hollow portion 1 of the semiconductor ceramic cylinder 11 obtained by press molding.
2 is formed by filling the semiconductor ceramic particles 13 obtained by the spray method and firing the semiconductor ceramic particles 13 and the semiconductor ceramic cylinder 11 together.

At this time, the contact portions between the semiconductor ceramic particles and between the semiconductor ceramic particles and the semiconductor ceramic cylinder are melted. In this case, if the particle diameter of the semiconductor porcelain particles is small, if the sintering is insufficient, the semiconductor porcelain particles may fall off from the semiconductor porcelain cylinder. On the other hand, if the firing is excessive, the melting of the semiconductor porcelain particles proceeds too much, and as shown in this figure, the semiconductor porcelain particles and the semiconductor porcelain cylinder are integrated with a small gap 16 remaining, so-called sponge type. In some cases. As shown in this figure, when the semiconductor ceramic particles and the semiconductor ceramic cylinder are integrated into a large sponge-type mass with a slight gap left therebetween, the electrical resistance is reduced and the thermal resistance is also reduced.

The arc discharge occurs when a part of the discharge lamp electrode is evaporated due to high temperature. In other words, the arc discharge cannot be maintained unless the temperature of the discharge lamp electrode is high. Therefore, the formation of an arc spot due to local temperature rise of the discharge lamp electrode is necessary to maintain the arc discharge, and if the arc spot is not formed, the arc discharge cannot be maintained, Arc discharge may stop.

[0021]

SUMMARY OF THE INVENTION The invention of the present application has been made in view of such a situation, and the present invention provides a discharge lamp electrode capable of reliably maintaining arc discharge. The discharge lamp electrode provided in the present application is such that a discharge lamp electrode material particle made of a high melting point metal or semiconductor porcelain is filled in a hollow portion of a bottomed cylindrical electrode cylinder made of a high melting point metal or a semiconductor ceramic. Has an aggregated porous structure in which only the contact portions of the particles are molten.

Since the discharge lamp electrode does not form a large lump and has a high thermal resistance, the temperature of the particles to be subjected to arc discharge easily rises, an arc spot is reliably formed, and the arc discharge is easily maintained.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. The basic configuration of the ceramic cathode discharge lamp using the discharge lamp electrode of the present invention is the same as the configuration of the conventional ceramic cathode discharge lamp shown in FIG. The description of the outline of the ceramic cathode discharge lamp according to the above is omitted. FIG.
(A) is a cross-sectional view of a discharge lamp electrode according to the present invention. The discharge lamp electrode is a bottomed cylindrical semiconductor porcelain having a high melting point or good sputtering resistance, one of which is an open port. For example, an electrode cylinder 21 made of a Ba (Zr, Ta) O ₃ -based semiconductor ceramic, and a granular semiconductor ceramic 23 housed in a hollow portion 22 formed in the electrode cylinder 21.
It is composed of

The size of the electrode cylinder 21 is shown in FIGS.
0.9 mm inside diameter, 1.9 mm outside diameter,
There are ones with a length of 2.3 mm and ones with an inner diameter of 1.6 mm, an outer diameter of 2.6 mm and a length of 2.3 mm. If the particle size of the semiconductor porcelain 23 is as small as 5 μm or less, melting (neck grouse) of the particles proceeds during firing or arc discharge, and a sponge-type porous structure may be formed. If it is large, the heat capacity of the particles is large, so that an arc spot is difficult to be formed. Therefore, it is desirable that the particle size of the semiconductor porcelain 23 is 5 μm to 500 μm.

FIG. 5B is an enlarged sectional view of the discharge lamp electrode. This discharge lamp electrode also has a hollow portion 22 of a semiconductor ceramic cylinder 21 similarly to the conventional discharge lamp electrode shown in FIG.
Is filled with semiconductor porcelain particles 23, but has a sponge-type porous structure in which the semiconductor porcelain particles and the semiconductor porcelain cylinder of the discharge lamp electrode shown in FIG. In contrast, the discharge lamp electrode shown in FIG. 5B has an aggregate in which only the contact portions between the semiconductor ceramic particles and the semiconductor ceramic cylinder are partially melted.
ate) type porous structure. In this case, the porosity is desirably 15% or more.

In this discharge lamp electrode, similarly to the conventional discharge lamp electrode shown in FIG. 3, a hollow portion 22 of a semiconductor ceramic cylinder 21 is filled with semiconductor ceramic particles 23,
3 and the semiconductor ceramic cylinder 21 are fired together. At this time, by slightly lowering the firing temperature and adjusting the firing atmosphere, the semiconductor ceramic particles and the semiconductor ceramic particles and the semiconductor ceramic cylinder are formed. By controlling the melting of the contact portion, an aggregate-type porous structure in which only the contact portion between the semiconductor ceramic particles and the semiconductor ceramic cylinder is partially melted is obtained.

The operation of the discharge lamp electrode of the present invention is shown in the enlarged view of FIG. In FIG. 6, (a) shows semiconductor ceramic particles of the discharge lamp electrode of the present invention shown in FIG. 5 having an aggregate-type porous structure,
(B) shows the semiconductor ceramic particles of the conventional discharge lamp electrode shown in FIG. 4 having a sponge-type porous structure. In these figures, 30 is the semiconductor porcelain particles of the discharge lamp electrode of the present invention, 31 is the semiconductor porcelain particles of the conventional discharge lamp electrode, and the solid line A shows the arc discharge path and the dotted line H shows. Are the conduction paths of heat flowing through the semiconductor porcelain particles, and 32 and 33 are arc spots.

The semiconductor porcelain particles 31 of the prior art shown in (b) have a sponge-type porous structure, so that there are many melting points between the semiconductor porcelain particles and between the semiconductor porcelain particles and the semiconductor porcelain cylinder. . Therefore, the semiconductor porcelain particles 31
The area of the heat conduction path H flowing through the inside is large as shown in the figure. Therefore, much of the heat generated in the arc spot 33 by the arc A is lost due to conduction, and the temperature of the arc spot 33 decreases, so that the arc cannot be stably maintained.

On the other hand, the semiconductor porcelain particles 30 shown in FIG. 3A have an aggregate-type porous structure, so that the semiconductor porcelain particles 30 melt between the semiconductor porcelain particles and between the semiconductor porcelain particles and the semiconductor porcelain cylinder. Is partial. Therefore, the cross section of the conduction path H of the heat flowing through the semiconductor ceramic particles 30 is small as shown in the figure. Therefore, the heat generated in the arc spot 32 by the arc A is rarely lost by conduction, the temperature of the arc spot 32 is maintained at a high temperature, and the arc is generated stably.

Incidentally, the temperature of the arc is as low as 50.
0-1000K, and as high as 3000-6000K. Further, the inside of the fluorescent discharge tube is maintained at a low pressure.
Therefore, when a material having a low melting point is used for the electrode, the electrode evaporates, and the life of the discharge tube is shortened. Therefore, the porcelain particles used for the electrode material need not only be a semiconductor but also have a high melting point. Ceramic materials satisfying these conditions include Ti as a carbide ceramic.
C, ZrC, HfC, VC, TaC, NbC, WC, B
₄ C, and TiN,
VN, NbN, TaN, HfN, ZrN, BN, and LaB ₆ , CeB ₆ , B
Examples of the oxide ceramic include eB ₆ , NbB ₂ , TaB ₂ , and TiB ₂ , and examples of the oxide ceramic include an oxide semiconductor having a perovskite crystal structure and a semiconductor ceramic obtained by converting TiO ₂ or the like into a semiconductor by a semiconducting agent or reduction firing. .

In the embodiment described above, the discharge lamp electrode using a semiconductor ceramic as the electrode material has been described, but arc discharge is often performed using a metal as the electrode material. Further, since arc discharge is caused by the presence of the evaporated electrode material, any conductive material can be used for the arc discharge lamp electrode material. Therefore, it is possible to use a metal as the discharge lamp electrode material of the present invention, but the metal that can be used as the discharge tube electrode material is at least 1000 ° C.
It must be a high melting point metal having the above melting point. Practically, titanium, iron, nickel, zirconium, molybdenum, tantalum, tungsten, and niobium are suitable. Further, as a material used for the electrode cylinder, a high melting point metal other than ceramics is used.

[0032]

As is apparent from the above description,
The semiconductor ceramic particles or the high melting point metal particles according to the present invention have a small fusion portion between the particles or between the particles and the bottomed cylindrical electrode cylinder containing the particles, so that the thermal conductivity is reduced while maintaining the electrical conductivity. As a result, these particles become hot at the same time as the start of discharge and maintain a stable temperature state sufficient to maintain an arc spot.As a result, a high electron flow density can be obtained and a stable discharge can be performed. Will be

[Brief description of the drawings]

FIG. 1 is a perspective view of a backlight for a liquid crystal display device to which a fluorescent discharge lamp is applied.

FIG. 2 is an overall sectional view and a tube end sectional view of a conventional fluorescent discharge lamp for backlight using a tungsten filament.

FIG. 3 is a sectional view of a tube end portion of a conventional fluorescent lamp for a backlight using a semiconductor ceramic discharge lamp electrode.

FIG. 4 is an enlarged cross-sectional view of a semiconductor ceramic discharge lamp electrode of the backlight fluorescent discharge lamp shown in FIG. 3;

FIG. 5 is a cross-sectional view and an enlarged cross-sectional view of a semiconductor ceramic discharge lamp electrode of the fluorescent discharge lamp for a backlight according to the present invention.

FIG. 6 is an operation explanatory view of the semiconductor ceramic discharge lamp electrode of the present invention and a conventional semiconductor ceramic discharge lamp electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Back light source 2 Light guide plate 3 Fluorescent discharge lamp 4 Glass tube container 5 Lead wire 6 Filament 7 Mercury dispenser 10 Holding part 11 Electrode cylinder 12 Hollow part 13,23,30,31 Semiconductor porcelain 14 Mercury dispenser 15 Winding part 16 Air gap 21 Electrode cylinder 22 Hollow part 32,33 Arc spot A Arc discharge path H Heat conduction path

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-251044 (JP, A) JP-A-4-43546 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) H01J 61/067

Claims (5)

(57) [Claims] The discharge lamp comprises an electrode cylinder having a bottomed cylindrical shape, which is a material having conductivity, and a discharge lamp electrode material, which is a high melting point material having conductivity filled in a hollow portion of the electrode cylinder. A discharge lamp electrode, wherein the electrode material has an aggregate type porous structure. 2. The discharge lamp electrode according to claim 1, wherein said high melting point material is a semiconductor ceramic. 3. The discharge lamp electrode according to claim 1, wherein said high melting point material is a high melting point metal. 4. The discharge lamp electrode according to claim 1, wherein said electrode cylinder is a semiconductor ceramic. 5. The discharge lamp electrode according to claim 1, wherein said electrode cylinder is made of a high melting point metal.