JPH03250547A - Small-sized electric discharge lamp - Google Patents

Abstract

PURPOSE:To prevent a bulb from damage by using a pair of electrodes set in the bulb as emitter for alkali earth metal expressed by a specific formula, and installing these electrodes on the inner wall of a hollow metal pipe. CONSTITUTION:A coating of fluorescent substance 2 is applied to the inner wall of a tubular bulb 1 for a small-sized discharge lamp, and a hollow metal pipe 4 constituting an electrode upon connecting to a lead 3 provided has a tip opening 5, and on the inner wall of this pipe 4 an emitter 6 is provided, to which MgO powder of composition as in Formula I is baked fast. In the Formula I, Me is alkali earth metal, and 0<=x<=1. The lead 3 may for ex. be a Dumet wire of 0.3mm in dia., while the hollow metal pipe 4 is made of Ni or stainless steel, and the bore of the opening 5 dimensions 0.6mm. thus tip opening 5 of the pipe 4 is smaller in dia. than its central part, and vapor from emitter 6 during the lamp in lighting will never attach to the tube wall of the lamp to ensure that the whole bulb is free of damaging.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a compact discharge lamp used as a fluorescent lamp for a backlight of a liquid crystal display or a UV lamp for an ultra-compact UV sterilizer.

[Prior Art] A small discharge lamp used as a fluorescent lamp for the backlight of a conventional liquid crystal display is equipped with a pair of opposing electrodes inside a glass tube whose inner surface is coated with phosphor.
The pair of electrodes is coated with an emitter, and the power consumption is less than a few watts.
77, No. 5, 1989," discharge lamps of less than IW are often used.

[Problems to be Solved by the Invention] As mentioned above, the structure of the electrode of the conventional small discharge lamp is 1. For example, as disclosed in Japanese Patent Application Laid-open No. 64-33844, etc., the electrode structure is pipe-shaped, and the tip of the pipe is Because the emitter has the same diameter as the central part, the emitter evaporates and scatters into the bulb or adheres to the tube wall due to discharge, resulting in attenuation of the light intensity. However, it had the disadvantage of shortening its lifespan.

Furthermore, JP-A No. 64-33844 states that a ring-shaped barium getter is provided at the tip of a pipe-shaped electrode, and that the inner diameter of this barium getter is made smaller than the center of the pipe-shaped electrode. The above problem occurs because there is a space between the electrode and the barium getter.

The present invention was made to solve such problems,
It is an object of the present invention to provide a compact discharge lamp that can achieve a stable point lamp and a long life by preventing evaporation and scattering of the emitter even when the lamp is turned on for a long time.

[Means for Solving the Problems] In order to achieve the above object, in the small discharge lamp of the present invention, a pair of electrodes disposed inside the bulb are arranged along the inner wall of the hollow metal pipe, MeO, □ (However, M
e is an alkaline earth metal, and an emitter represented by 0≦X≦1) is disposed, and the opening at the tip of the pipe is formed to have a smaller diameter than the center of the pipe.

[Function] With the above configuration, even if the emitter evaporates during lighting, it is less likely to scatter and adhere to the tube wall of the lamp, and most of the evaporated emitter is transferred to another part of the inner wall of the pipe. The emitters that have adhered to certain places and remain within the inner wall of the pipe and have evaporated can also contribute to light emission again.

[Embodiment] FIG. 1 is an enlarged view showing the configuration of the main parts of a small discharge lamp which is an embodiment of the present invention.

In Fig. 1, 1 is a bulb on the tube wall of a small discharge lamp;
2 is a phosphor coated on the inner wall of this bulb l, 3 is a lead wire, 4 is a hollow metal pipe connected to this wire 3 and constitutes an electrode, 5 is an opening at the tip of this hollow metal pipe 4, and 6 is an opening at the tip of this hollow metal pipe 4. The emitter provided on the inner wall of the hollow metal pipe 4 is baked with M, 0 powder as M, O, -1.

The lead wire 3 in the device of FIG. 1 has a diameter of, for example, 0.3 mm.
The hollow metal pipe 4 is made of nickel or stainless steel, and the opening diameter of the tip opening 5 is 0.6 mm. In an experiment, a 0.5W lamp was lit using an inverter-based power source, and when the initial light intensity at that time was set to 1, it was possible to maintain 70% of the initial power after 3000 hours of lighting. .

In the configuration shown in Fig. 1, if there is no phosphor 2, it would be equivalent to an ultra-compact low-pressure mercury lamp;
It becomes a V radiation light source.

In addition to the structure of the hollow metal pipe shown in Fig. 1, as shown in 4a in Fig. 2(a) and 4b in Fig. 2(b), the openings 5a and 5b at the ends are constricted, and the center It is conceivable to have a shape with a diameter smaller than that of the section. The hollow metal pipes 4a and 4b in FIG. 2 also have very little chance of the emitters 6a and 6b scattering onto the inner wall of the bulb, or evaporating and adhering to the wall of the bulb, and the discharge is sufficiently maintained.
It can be seen that if the sizes of the tip openings 5a and 5b are appropriately selected, the arc will be stable, the electrodes will be less damaged, and the lamp will have a long life.

Incidentally, in the above embodiments, a discharge lamp is described which has a single torrent wire passing through the inside and outside in order to achieve electrical continuity at the end of the tube wall glass bulb.

A special shape without a Riet wire that has a metal thin film on the inside and outside at both ends of the glass bulb, and uses the glass bulb as a dielectric to generate a discharge between the inner metal (electrodes). This electrode structure can also be applied to electrode discharge lamps.

[Effects of the Invention] As explained above, the pair of electrodes disposed in the bulb of the present invention are formed along the inner wall of the hollow metal pipe according to the general formula M, 0I-X (where Me is an alkaline earth metal). , 0 ≦ Since it does not stick to the pipe wall, it does not damage the valve, and it can also stick to the evaporated emitter or another part of the inner wall of the hollow metal pipe and function as an emitter again. I'll come.

[Brief explanation of drawings]

FIG. 1 is an enlarged view showing the structure of the main parts of a small discharge lamp which is one embodiment of the invention, and FIG. 2 is a diagram showing the structure of the electrodes of another embodiment of the invention. In the figure, 1: Bulb 2, phosphor rieet wire 4: Hollow metal pipe: Emitter with open end

Claims (1)

[Claims] In a small discharge lamp using a low-pressure mercury lamp containing mercury and a rare gas or a low-pressure mercury discharge containing a fluorescent lamp in a tube-shaped bulb, a pair of electrodes disposed in the bulb include: An emitter expressed by the general formula MeO_1_-_X (where Me is an alkaline earth metal, 0≦X≦1) is arranged along the inner wall of the hollow metal pipe, and the opening at the tip of the pipe is located at the center of the pipe. A small discharge lamp characterized by being formed to have a smaller diameter than the part.