JPH09204899A - Cold cathode discharge lamp and lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate flickering, make starting operation easy, and make the size small by constituting an inside electrode with a metal having a work function lower than that of an outside electrode in a cylindrical discharge lamp comprising the inside electrode and the outside electrode surrounding the inside electrode. SOLUTION: In a cold cathode discharge lamp in which an electrode 3 formed by connecting a lead wire 6 to both edges of a straight tube-shaped bulb is sealed, the electrode 3 is constituted with a rod-shaped inside electrode 4a made of Zr or the like and a cylindrical outside electrode 5A surrounding the inside electrode 4A, made of a Ni plate having a work function higher than that in the inside electrode 4A. High frequency voltage is applied to the electrode 3, and when discharge is generated between the electrodes 3 at both ends, a discharge starting point is produced on the surface of the inside electrode 4A having the work function lower than the outside electrode 5A, and the discharge is continued between the electrodes 4A, 4A. Since the discharge is an electrode glow only from the electrode 4A, the flickering of a positive column attendant upon the movement of the electrode glow is eliminated, and since the electrode 4A is surrounded by the electrode 5A, sputtering is reduced, blackening is suppressed, the life is lengthened, and a starting characteristic is kept good.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode discharge lamp used in liquid crystal televisions, liquid crystal display devices, OA equipment such as facsimiles and copiers, and illumination for backlight devices, document reading devices, etc. incorporating the cold cathode discharge lamps. Regarding the device.

[0002]

2. Description of the Related Art There is a strong demand for thin and lightweight display devices such as televisions and liquid crystal display devices and OA devices such as facsimiles, and accordingly, low-pressure discharge lamps and lighting devices mounted on these devices. The miniaturization is also recommended.
For example, a fluorescent lamp mounted on a backlight of a liquid crystal display device has a small input, and has a glass tube bulb having an outer diameter of 5 mm or less, which is smaller than that of a fluorescent lamp for general lighting, and an elongated one having a total length of 200 to 250 mm. Is used, and low power consumption, high brightness, high color rendering properties, and long life are required at the same time. In particular, since these devices are for consumer use, the lamps are not replaced in principle, and a life of 10,000 hours or more is required.

For this reason, the small fluorescent lamp for a backlight is designed to have an optimal electrode from the viewpoint of life as well as current and voltage, the type of rare gas to be enclosed, etc. so as to be compatible with low power consumption.

In the low-pressure discharge lamp, there are hot cathode type or cold cathode type electrodes, but in the hot cathode type using a coiled filament, the electrode space becomes large and the lamp bulb has a small diameter. It is difficult to make it into a small size, and there is a limit to miniaturization, and a cold cathode type in which plate-shaped or cylindrical electrodes can be used is attracting attention.

As the cold cathode type electrode of this low pressure discharge lamp, for example, a metal such as nickel Ni is formed into a rod-shaped body or a plate-shaped body, a flat plate is a V-shaped body, or a cylindrical body. There is one in which a rod-shaped body is arranged inside the cylindrical body.

This discharge lamp has a cold cathode electrode B
By providing an electron emissive material such as a, Sr, Ca, or ZrAl, the discharge is facilitated and the life is extended. This lamp performs a predetermined discharge while the electrode has an electron emitting substance, but becomes difficult to discharge as the electron emitting substance is consumed, and the starting voltage rises to reach the end of its life.

In the hollow electrode of the above-mentioned electrode, which has a cylindrical body, the electron emitting substance is provided inside the cylindrical body, so that a large amount of the electron emitting substance can be held and the electron emitting substance can be held. Since it has an extraordinary effect called the hollow electrode effect that can prevent the spatter from occurring and can quickly shift to arc discharge at the time of starting, it is widely used as a long-life electrode.

[0008]

However, it is easy to obtain the hollow electrode or the hollow electrode effect of the cylindrical body as described above.
The glow of the V-shaped electrode is stable, but when the entire cold cathode electrode is made of the same metal material, the electrode glow (gloomy glow around the electrode) moves irregularly on the metal surface of the electrode. As a result of this movement of the electrode glow, the positive columns near the electrodes also move and appear to flicker, which is a problem in terms of appearance.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a cold cathode discharge lamp which is easy to start even if it is downsized and has no flicker, and an illumination device incorporating this lamp.

[0010]

A cold cathode discharge lamp according to claim 1 of the present invention comprises a cold cathode type electrode comprising an inner electrode and an outer electrode surrounding the inner electrode in a glass bulb, and a discharge medium. In the above discharge lamp, the inner electrode of the electrode is made of a metal having a lower work function than the outer electrode.

The discharge of this discharge lamp occurs between the inner electrodes of said electrodes. That is, the inner electrode and the outer electrode are made of different metal materials, and the work function of the inner electrode is lower than that of the outer electrode surrounding the inner electrode.Therefore, the discharge starting point is generated on the surface of the inner electrode, and the discharge is sustained between the inner electrodes. To be done. Since this discharge is an electrode glow only from the surface of the inner electrode, it is possible to prevent the flicker of the positive column due to the movement of the electrode glow. Further, since the inner electrode is surrounded by the cylindrical outer electrode, spattering is prevented and wear can be reduced over a long period of time.

In the cold cathode discharge lamp according to claim 2 of the present invention, the inner electrode of the cold cathode type electrode comprises at least one of Zr and Al, and the outer electrode comprises at least one of W, Ni, Cu and Fe. It has a feature.

By the combination of the electrode materials, the action of the above-mentioned claim 1 is achieved.

A cold cathode discharge lamp according to a third aspect of the present invention is characterized in that the cold cathode type electrode is formed so that a cylindrical outer electrode surrounds a rod-shaped inner electrode.

Since the outer electrode surrounds the inner electrode except for the side of the discharge path, the hollow electrode effect is exerted, and the operation of claim 1 is achieved.

In the cold cathode discharge lamp according to a fourth aspect of the present invention, the outer electrode is formed by a V-shaped plate body in which the cold cathode electrode has a rod-shaped or plate-shaped inner electrode and is expanded toward the discharge path. It is characterized in that it is formed.

Since the outer electrode surrounds most of the inner electrode, it exhibits a hollow electrode effect, thereby achieving the action of claim 1.

The cold cathode discharge lamp according to claim 5 of the present invention is formed by bonding the inner electrode to the inner surface side of the outer electrode which is a V-shaped plate body in which the cold cathode electrode is expanded toward the discharge path. It is characterized by being.

Since the outer electrode surrounds most of the inner electrode, it exhibits a hollow electrode effect, thereby achieving the action of claim 1.

An illumination device according to a sixth aspect of the present invention comprises a base body and the cold cathode discharge lamp according to any one of the first to fifth aspects mounted on the base body. Is characterized by.

The high-quality discharge lamp according to any one of claims 1 to 5 can be turned on to improve the light emission characteristics of the lighting device.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a partially cutaway sectional front view showing a cold cathode discharge lamp, and FIG. 2 is a partially sectional front view showing an enlarged cold cathode electrode shown on the right side of FIG.

The cold cathode discharge lamp L has a power consumption of about 10 W, an outer diameter of about 5 mm and a length of about 300 m.
m of soda lime glass or lead glass or other soft glass such as a straight tube type tubular valve 1 at both ends with a sealing portion 2,
2 are formed. And, in the sealing portions 2 and 2 at both ends,
Lead wires 6, 6 made of copper-plated iron wire or iron alloy wire having an outer diameter of about 0.4 mm and having cold cathode type electrodes 3, 3 connected to their respective ends are hermetically sealed. This electrode 3
Has an outer diameter of about 1 mm made of Zr (zirconium) inside
The rod-shaped inner electrode 4A and the outer electrode 5A surrounding the inner electrode 4A, which has a thickness of about 0.2 mm and is formed in a cylindrical shape by a Ni (nickel) plate made of a material different from that of the inner electrode 4A. The diameter of one end of the electrode 5A is reduced and the inner electrode 4A and the lead wire 6 are overtightened to be integrated with each other, and mechanically and electrically connected and fixed.

The bulb 1 is filled with a rare gas such as xenon (Xe) or neon (Ne) for several tens to 200 Torr, for example 100 Torr, as a discharge medium. Further, a phosphor film 7 having a predetermined light emitting region is formed on the inner surface of the bulb 1 as necessary, and a proximity conductor (not shown) is attached to the outer surface of the bulb 1.

Then, a base (not shown) is joined to the sealing portions 2 and 2, or a power supply line (not shown) is connected to the lead wire 6 to complete the discharge lamp L. The discharge lamp L having the above configuration is connected to a lighting device (not shown) and is lit. That is, when a switch which connects to the power source is turned on, a high frequency voltage of several tens KHz is applied from the inverter to the caps and the adjacent conductors at both ends of the lamp L mounted in the socket (not shown) through the wiring. First, a glow discharge occurs between the close conductor and the other electrode 3 on the side close to this conductor, and this discharge causes the other electrode 3 and one electrode 3 of the same pole as the close conductor.
Then, secondary electrons are emitted from both electrodes 3 and 3 by the ions of the initial plasma, and discharge is started in the discharge path 8 between the electrodes 3 and 3 (right and left). Then, the rare gas in the bulb 1 is excited to generate ultraviolet rays, and the ultraviolet rays are converted by the phosphor film 7 formed on the inner surface of the bulb 1 to become visible light and emitted from the outer surface of the bulb 1.

This discharge is generated between the inner electrodes 4A, 4A of the electrodes 3, 3. That is, the inner electrode 4 made of rod-shaped Zr (zirconium) having a lower work function than Ni (nickel) forming the cylindrical outer electrode 5A.
A discharge starting point is generated on the surface of A, and the discharge is generated by this inner electrode 4A,
It lasts between 4A. Since this discharge is an electrode glow only from the surface of the inner electrode 4A, it is possible to prevent the flicker of the positive column due to the movement of the electrode glow. Further, since the inner electrode 4A, which is the starting point of the discharge, is surrounded by the outer electrode 5A having the cylindrical hollow electrode effect, spattering is prevented, wear is reduced over a long period of time, and blackening of the valve can be reduced and starting is possible. The life can be extended without deteriorating the characteristics.

3 and 4 show another embodiment of the cold cathode electrode 3 used in the discharge lamp L according to the present invention. FIG. 3A is a front view and FIG. In the side view of a), the same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. The outer electrode 5B shown in the drawing is, for example, Ni.
A combination of two (nickel) plates is formed so as to have a V shape when viewed from the front, which is widened toward the discharge path 8 side.

In the structure shown in FIG. 3, the plate-shaped outer electrodes 5B and 5B are fixed to the inner electrode 4B made of, for example, Zr (zirconium) by welding so as to form a V shape on both sides of one end of the inner electrode 4B. The lead wire 6 is welded to the rear end.

In FIG. 4, the plate-shaped outer electrodes 5B and 5B are fixed to both sides of one end of the lead wire 6 by welding so as to form a V shape, and the plate-shaped outer electrodes 5B and 5B face each other. Inner electrodes 4C, 4C made of, for example, plate-shaped Zr (zirconium) are joined to the inner surface side by welding.

The discharge lamp L using these cold cathode electrodes 3 has inner electrodes 4B and 4C as in the above embodiment.
Although not entirely surrounded by the outer electrode 5B except the discharge path 8 side, most of the portion is covered by the outer electrode 5B, so that a hollow electrode effect is exhibited and the discharge is made of a material having a low work function. Occurs on the inner electrodes 4B and 4C,
It is possible to obtain substantially the same operational effects as the above-described embodiment.

The materials constituting the inner electrodes 4A, 4B, 4C and the outer electrodes 5A, 5B are Zr-Ni (A), Zr-W (tungsten), A in addition to Zr-Ni described in the embodiment.
l (aluminum) -Cu (copper), Al-Ni, Al-
It may be a combination of Fe (iron) and these alloys, in short, the inner electrodes 4A, 4B and 4C are the outer electrodes 5.
Any material may be used as long as it has a work function lower than that of the materials forming A and 5B, and a discharge starting point is generated on the surfaces of the inner electrodes 4A, 4B and 4C.

The cold cathode discharge lamp L having the above structure
Is used by being incorporated in a lighting device. FIG. 5 is an exploded perspective view showing an example of the illumination device D. In FIG.
Reference numeral 1 is a base, and D2 is a reflecting mirror provided on the base D1, on which the discharge lamp L is mounted. Further, a lighting device D3 is provided on the back surface of the substrate D1, and a light diffusion plate D is provided at the opening of the reflecting mirror D2.
4 are attached. The lighting device D is used as a backlight of a liquid crystal display device such as a personal computer or a television, or as a backlight of a display panel of a display or a fixture for normal lighting, and incorporates the above-mentioned high-quality discharge lamp. As a result, it is possible to provide a lighting device with improved light emission characteristics.

The present invention is not limited to the above embodiment. For example, the discharge lamp is not limited to a fluorescent lamp, but can be applied to other types of discharge lamps such as a lamp that emits a rare gas, and other types of low-pressure discharge lamps such as an ultraviolet radiation lamp. It may be a discharge lamp or the like in which a luminescent substance such as Further, the glass bulb forming the discharge path is not limited to the straight tube shape, but may have a curved tube shape such as a U-shape, a W-shape or an annular shape, or a shape in which a plurality of straight tubes are connected in series.

Further, for assembling both the inner electrode and the outer electrode constituting the electrode, means such as welding, overtightening, and joining can be applied.

Further, as for the electrodes, not all of the electrodes provided on one lamp have the structure according to the present invention,
It suffices that at least one electrode provided on one lamp has a structure according to the present invention.

Further, the encapsulation of mercury is not limited to liquid mercury,
A mercury-releasing alloy such as Ti ₃ Hg may be formed on the surface of the outer electrode, or a getter material such as a Zr—Al alloy may be provided.

Furthermore, the lighting device of the present invention is not limited to the one described in the embodiment, and the three bodies of the base, the reflecting mirror and the light diffusing plate may not necessarily be provided, and the lighting device is integrated. It does not have to be done. Further, the lighting device is used for a stationary or on-vehicle liquid crystal display device, a backlight for a liquid crystal television or a decoration device, a reading device for a facsimile, an OA device for exposing a copying machine, or a normal lighting device. It goes without saying that it can be widely used as a lighting device by mounting it on a fixture or a lighting device.

[0038]

According to the first and fifth aspects of the present invention, since the electrode glow can be surely caused only from the inner electrode, the flicker of the positive column near the electrode is eliminated. Also, by providing a hollow electrode effect, electrode sputtering is prevented, electrode wear is reduced over a long period of time, bulb blackening can be reduced, and a long-life lamp without deteriorating starting characteristics is provided. can do.

According to the second aspect of the present invention, the electrode can be easily obtained from a general-purpose material, and there is no risk of cost increase.

According to the invention of claim 3 of the present invention, since the outer electrode surrounds the inner electrode except for the discharge path side, a hollow electrode effect is exhibited and the effect of claim 1 is achieved.

According to the fourth and fifth aspects of the present invention, since the outer electrode surrounds most of the inner electrode, the hollow electrode effect is exhibited and the effect of the first aspect is achieved.

According to the sixth aspect of the present invention, it is possible to provide a lighting device in which a high-quality discharge lamp is turned on and the light emission characteristics are improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional front view showing an embodiment of a cold cathode discharge lamp of the present invention.

FIG. 2 is an enlarged sectional front view showing an electrode on the right side of the lamp of FIG.

3 shows another embodiment of the electrode of the cold cathode discharge lamp of the present invention, FIG. 3 (a) is a front view, and FIG. 3 (b) is a side view of FIG. 3 (a).

FIG. 4 shows another embodiment of the electrode of the cold cathode discharge lamp of the present invention, FIG. 4 (a) is a front view, and FIG. 4 (b) is a side view of FIG. 4 (a).

FIG. 5 is an exploded perspective view of an illumination device incorporating a cold cathode discharge lamp.

[Explanation of symbols]

 L: cold cathode discharge lamp 1: glass bulb 2: sealing part 3: cold cathode (electrode) 4A, 4B, 4C: inner electrode 5A, 5B: outer electrode 6: lead wire D: lighting device D1: substrate

Claims (6)

[Claims] 1. A discharge lamp in which a cold cathode electrode composed of an inner electrode and an outer electrode surrounding the inner electrode and a discharge medium are sealed in a glass bulb, wherein the inner electrode has a work function higher than that of the outer electrode. A cold cathode discharge lamp characterized by being made of a low metal. 2. The cold cathode type electrode, wherein the inner electrode is Zr, Al
The cold cathode discharge lamp according to claim 1, wherein the outer electrode is made of at least one of W, Ni, Cu, and Fe. 3. The cold cathode discharge lamp according to claim 1, wherein the cold cathode type electrode is formed such that a rod-shaped inner electrode is surrounded by a cylindrical outer electrode. 4. The cold cathode electrode is formed so that the rod-shaped or plate-shaped inner electrode is covered with an outer electrode formed of a V-shaped plate body expanded to the discharge path side. 1. The cold cathode discharge lamp according to 1. 5. The cold cathode type electrode is a V which is expanded to the discharge path side.
The cold cathode discharge lamp according to claim 1, wherein the inner electrode is formed by being joined to the inner surface side of the outer electrode formed of a letter-shaped plate body. 6. A base and a base mounted on the base.
An illumination device comprising: the cold cathode discharge lamp according to claim 5.