JPH02230653A - low pressure discharge lamp - Google Patents

Abstract

PURPOSE:To obtain a low voltage mercury lamp of longevity and of high efficiency by providing a counter electrode composed of a metallic plate for which face-to-face dimension is specified, in a discharge container in which gas for discharge is sealed. CONSTITUTION:In both edges of a straight tubular discharge container 4, cathodes 1, 2 are sealed, with which leads 5, 6 are connected, respectively. The discharge container 4 is formed out of a soda glass tube of inside diameter of 5.7mm, length of 270mm, applying a mixture of a rare earth fluorescent material Y2O3:Eu, MgAl11O19:Ce, Tb, 3Sr3(PO4).CaCl2 to the inside thereof, as a fluorescent material 3. A primary component of the gas for discharge is defined as rare gas, and when the atomic weight of the rare gas is defined as M, the pressure of the rare gas expressed by Torr is defined as 280-2000/M. Namely, mixed gas of 10Torr of argon and mercury-arc is used. For a counter electrode, metallic plates 11, 12 of iron-nickel alloy of the width of 3mm, length 6mm are used, whose face-to-face dimension is determined as 0.2-0.7mm by spacers 13, 14. To the inside of the metallic plates 11, 12, a getter 15 including zirconium is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-pressure discharge lamp, and particularly to a small-diameter low-pressure discharge lamp such as a fluorescent lamp for a backlight. [Prior Art] Hot cathode discharge lamps and cold cathode discharge lamps are described on pages 759 to 760 of the Illumination Handbook (May 1973, Ohmsha) edited by the Illumination Institute of Japan. Also. Hot cathode type fluorescent lamps are described on page J60 of the same document. Regarding the structure of the hot cathode, see Part 1 of the Lighting Band Book (November 1988, Ohmsha) edited by the Illuminating Society of Japan. [Problem to be solved by the invention] described on page 2 1 In the above-mentioned conventional hot cathode type low-pressure discharge lamp, in order to heat the electrodes by applying electricity, This has the disadvantage that two lead wires are required and the structure of the tube end of the discharge tube becomes complicated. especially. If the dimensions of the discharge vessel are small, the above-mentioned drawbacks are fatal. Also,
Cold cathode low pressure discharge lamps have one lead wire for each electrode, but have the drawback of high cathode drop voltage and therefore low efficiency. Furthermore, when the discharge current was 10 mA or more, the service life was short. An object of the present invention is to provide a low-pressure discharge lamp with a simple tube end structure, high crystal efficiency, and long life.

[Means to solve the problem]

-1 The purpose of item 2 is to seal a discharge gas in a discharge container, and to connect at least two metal plates with a distance of 0 between the blood of the metal plates.
．． This is achieved by providing a pair of electrodes characterized by a structure in which they are provided facing each other such that the distance between them is between 2 + m and 0.7 + w. Furthermore, the above object can be further achieved by making the emissivity of at least a portion of the outer surface of the metal plate larger than the emissivity of the inner surface of the metal plate and by applying an electron emitting substance to the inner surface of the metal plate. more accomplished.

[Effect]

At least two metal plates are connected so that the distance between the metal plates is 0.
．． When a pair of electrodes are provided facing each other with a distance between 2 mm and 0.7 +++ m, glow enters the gap created between the metal plates,
The so-called hollow cathode result reduces the cathode drop voltage and reduces cathode losses, resulting in a highly efficient low-pressure discharge lamp.

When the emissivity of at least a portion of the outer surface of the metal plate is set to be higher than the emissivity of the inner surface of the metal plate, heat radiation from the metal plate increases and the temperature of the metal plate decreases. , the density of the noble gas between the metal plates where the cathode drop is present increases, and therefore the electrode material scattered from the cathode is pushed back to the cathode, reducing wear on the cathode and increasing the length of time.
A long-life electrode is obtained. The above effect is achieved when the emissivity of the outer surface of the metal plate is O. It became especially large when it was 5 or more.

Also. B az as an electron emitting material on the inner surface of the metal plate.
c a WOa, B a 3Y2WO9,5 B a
When at least one selected from 0.2^10M, LaBs, and MgO is applied, the secondary electron emission effect increases, resulting in a reduction in cathode drop voltage and high efficiency. is stable in air and does not require activation, so there is no need for high-frequency heating of the electrode, etc.
The advantage is that the lamp manufacturing is simplified. Further, when a getter containing zirconium is provided on the inner surface of the gold Jrig plate, crystal efficiency and long life can be obtained because zirconium has a relatively small work function and zirconium absorbs impurity gas.

The above effect can be obtained by using a rare gas as the main component of the discharge gas, and setting the pressure of the rare gas expressed in Torr to 280/M or more and 2,000/M or less, where the atomic weight of the rare gas is M. [Embodiment] Fig. 1 shows a first embodiment of the present invention. Cathodes 1 and 2 are sealed at both ends of a straight tube-shaped discharge vessel 4.
．． 2 are connected to one lead wire 5, 6, respectively. Since there is only one lead wire, the structure of the tube end of the radiation tube is simple, and there is an advantage that manufacturing is simple. The advantage of having a simple structure at the tube end becomes greater when the inner diameter of the discharge tube is 81 m or less.

A metal plate 11.1 made of an iron-nickel alloy and having a width of 3 and a length of 6 ffl is shown in FIGS.
2 is O by spacer 13.14. A getter 15 containing zirconium is coated on the inside of the metal plates 11 and 12. Metal plate 1]. ．．
, 12 is, in principle, defined as the distance between the surfaces of the coated films of dorconium or electron emitting material when zirconium or electron emitting material is coated on the inside of metal plate 11.12. . In this embodiment, since the getter coating thickness is 0.05-, the distance between the metal plates 11 and 12 is Ill!
L is 0.4+na+.

At least a portion of the inner surface of the discharge tube 1 is coated with a phosphor 3. When inserting the phosphor coating film; if electrode 3 is present, electrodes 1 and 2 may come into contact with the phosphor film 3 and the phosphor may fall off, or blackening of the tube end may become more noticeable. Therefore, a system in which one lead wire is provided for one electrode is particularly advantageous.

In FIG. 1, the discharge tube 4 has an inner diameter of 5.7 m. length 270
mm soda glass tube, with rare earth phosphor YxOs: Eu, MgAQ zzO as the phosphor 3 on the inner surface.
te:Ce,']″b, 3 S r3(Po4) ・C
A mixture of a C Ilz was applied. The discharge gas is
Argon and mercury vapor at 10 TOrr.

When the low-pressure discharge lamp of the present invention described in ``2'' was lit with a discharge current of 30 kHz and 20 mA, the cathode drop voltage was
is 25% lower than when the distance is 1.0m, and the distance 1g L is 0.

]. 30% lower than the average of m, and a high-efficiency fluorescent lamp was obtained.

The second embodiment uses an electron emitter '79 13 a C I3 instead of the getter 15 in the electrode of the first embodiment.
V0 6 was applied to the outer surface of the metal plates 11 and 12, and powder of Cordierite h (2Mg0.2AffzOs.5SiOz) was applied using water glass as a binder.

While the emissivity of ordinary iron-nickel alloys at wavelengths of several μm to several tens of μm is 0.3 or less, the emissivity of cordierite is O. There is about 8, so the radiation of heat is large,
The temperature of the metal plate has decreased and the electrode has a longer lifespan. Also,
Since cordierite and water glass are electrical insulators, the glow reliably enters between the metal plates at the start of discharge, resulting in a stable discharge.One way to increase the emissivity of metal plates is to use iron-nickel alloy plates. A simple method is to oxidize the outer surface or add chromium. Good properties can be obtained even when ceramics such as alumina, zirconia, titania* S x C or carbon powder are applied. Figures 3(a) and 3(b) are respectively a front view and a side view of an electrode according to another embodiment of the present invention;
0 is wound around a rectangular coil to form the hollow part 31, and the distance between the long sides of the rectangle is the distance ML defined above. 32 has the advantage that the electrode corresponding to the electrode support wire is simple in construction.

FIGS. 4(a) and 4(b) are respectively an 1E plane view and a side view of an electrode according to another embodiment of the present invention.
2 is provided in a V-shape on the support shaft 16. 1-5
is an electron emitting substance LaBo. 20 is a black color with high emissivity and is carbon. The distance 1ijiL in this example is the average distance between the metal plates IN and 12, and the distance 1ijiL is the average distance between the metal plates IN and 12. I. ，
If the distance between the tip of 12 is 1], then the distance L is half of the distance 1]. In the electrode configured as in this example, the first
The effect is about 50% compared to the case where the metal plates 11 and 12 are provided in parallel as shown in the figure.

〔Effect of the invention〕

According to the present invention, a low-pressure discharge lamp with a long life and high efficiency can be obtained. In addition, a low-pressure discharge lamp with a simple tube end structure can be obtained, which has the advantage of simplifying the manufacturing method.

[Brief explanation of the drawing]

Figures 2 to 4 are cross-sectional views of one embodiment of the present invention.
Figures (a) and (b) are a positive i'f II view and a side view of an electrode according to an embodiment of the present invention, respectively. 1.2... Electrode, 11.12... Metal plate, 15...
Getter, 20 black objects. Gravel l Recording pole map (engineering) (b) Half country (oL) (b) Article (ku) (b)

Claims (1)

[Claims] 1. A discharge gas is sealed in a discharge container, and at least two metal plates are arranged such that the distance L between the surfaces of the metal plates is 0.2 mm.
1. A low-pressure discharge lamp characterized by having electrodes arranged opposite each other so as to be spaced apart from each other by 0.7 mm. 2. The main component of the discharge gas is a rare gas, and the pressure of the rare gas expressed in Torr is 280/M or more and 2,000/M or less, where M is the atomic weight of the rare gas. A low pressure discharge lamp according to claim 1. 3. The low-pressure discharge lamp according to any one of claims 1 and 2, characterized in that a getter containing zirconium is provided on the inner surface of the metal plate. 4. Ba_2C as an electron emitting material on the inner surface of the metal plate
aWO_6, Ba_3Y_2WO_9, 5BaO・2A
The low-pressure discharge lamp according to any one of claims 1 to 3, characterized in that the lamp is coated with at least one selected from l_2O_3, LaB_6, and MgO. 5. Any one of claims 1 to 4, characterized in that at least a part of the outer surface of the metal plate has a higher emissivity than the inner surface of the metal plate. Low pressure discharge lamp as described. 6. Any one of claims 1 to 4, characterized in that at least a portion of the outer surface of the metal plate is coated with a substance having a discharge emissivity of 0.5 or more. Low pressure discharge lamp as described. 7. The low-pressure discharge lamp according to any one of claims 1 to 6, characterized in that the metal plate is replaced by a closely spaced metal wire.