JPH0317951A - Low pressure rare gas discharge lamp - Google Patents

Abstract

PURPOSE:To restrain the reaction of a light emitting gas with residue contained in a glass bulb that may cause clean-up so as to elongate the life of a low pressure rare gas discharge lamp by providing an isolating film on the inner surface of the glass bulb surrounding a positive column. CONSTITUTION:A titanium oxide film 2 applied as an isolating film on the inner surface of a glass bulb 1 formed from soda glass is obtained by applying and drying tetrabutiltitanate thereon, and baking and dissolving it. A filament 6 is coated with an electron emitting material and a gas of one hundred percent xenon is sealed inside the glass bulb 1. The isolating film 2 provided on the inner surface of the glass bulb 1 restrains the reaction of the rare gas sealed inside the bulb with residue contained in the glass bulb. Clean-up is thereby prevented so as to elongate the life of the low pressure rare gas discharge lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a low-pressure rare gas discharge lamp filled with a rare gas as a luminescent gas. [Prior Art] Conventionally, for example, in Toshiba Review (Volume 40, No. 12), 1985, pages 1079 to 1082, a low-pressure rare gas containing xenon of several tens to several hundred Torr was introduced in place of mercury in ordinary fluorescent lamps. Discharge lamps are described.
This is because normal fluorescent lamps use mercury vapor, so the vapor pressure changes with changes in ambient temperature, and the light output also fluctuates, whereas xenon lamps do not use mercury, so they can be used over a wide temperature range. Taking advantage of the fact that the light output does not fluctuate, this product aims to expand its use as a light source for OA-related equipment. On the other hand, for example, as stated in the presentation by Mr. Okuno of Matsushita Electronics Co., Ltd. at the 1975 National Illumination Society Conference, in low-pressure rare gas discharge lamps filled with xenon, the filled gas pressure is reduced to 0. It is known that the luminous efficiency is the best when the pressure is extremely low, less than ITorr. However, as stated in the same presentation, in such a low pressure region, there was a problem in that xenon disappeared due to the clean-up phenomenon during discharge, and the lamp's life span was shortened in a short period of time. [Problems to be Solved by the Invention] As described above, in a low-pressure rare gas discharge lamp, lowering the filler gas increases brightness and improves efficiency, but the clean-up phenomenon results in an extremely short life span. For this reason, there was a problem in that in order to ensure longevity, the gas pressure had to be increased, at the expense of brightness and efficiency. This invention was made to solve this problem, and the cleanup phenomenon of low-pressure rare gas discharge lamps is closely related to the reaction between the residue in the glass tube and rare gas ions. We found that by isolating the residues in glass and glass from each other, their reactions with each other can be suppressed. Based on this result, we have developed a system that can prevent clean-up and achieve good brightness and efficiency even when the pressure of the rare gas sealed is extremely low. The purpose of this project is to provide a low-pressure rare gas discharge lamp with extended life in the low gas pressure region. [Means for Solving the Problems] The low-pressure rare gas discharge lamp according to the present invention is provided with an isolation film from the discharge space on at least the portion surrounding the positive column on the inner surface of the bulb. In addition, another invention is the above-mentioned invention, in which the interval g! The film is a thin titanium oxide film that is transparent. [Function] In this invention, the isolation membrane provided on the inner surface of the glass bulb suppresses the reaction between the rare gas sealed in the bulb and the residue in the glass bulb, thereby preventing clean-up and extending the life. do. In addition, by using a transparent titanium oxide thin film as the isolation membrane, it is possible to effectively suppress the reaction between the rare gas and the residue in the bulb, making it possible to further extend the life of the valve. [Embodiment] Figure 1 is a partial sectional view of a low-pressure rare gas discharge lamp showing an embodiment of the present invention. In the figure, (1) is a pipe diameter of 15
．． It is a 5+*m glass bulb. This glass bulb (1) contains 0.0% fluorine. 0.04% by weight, 0.0% chlorine
It is made of common soda glass that contains about 31% by weight as a residue. (2) is a titanium oxide film applied as an isolation film to the inner surface of the glass bulb (1), which was obtained by coating and drying tetrabutyl titanate, then baking and decomposing the film. ) is a phosphor layer provided on the surface of this titanium oxide film (2),
GP manufactured by Nix, G. Consists of green phosphor. (4) is a reflective film, ((5) is an aperture opening, and (6) is a filament. Although not particularly shown, this filament (6) is
) is coated with an electron-emitting substance, and the glass bulb (
11 is filled with 100% xenon gas. Further, a sufficient amount of barium getter is provided in the glass bulb (1) for the purpose of adsorbing impurity gas during its life. The lighting conditions were that the power source was a 30KHz sinusoidal high frequency, and the lamp current was constant at 100+aA. FIG. 2 shows the life characteristics of the lamp constructed as described above when the gas pressure is varied. The amount of titanium oxide deposited on the inner surface of the glass bulb was taken as a parameter. In addition, the lifespan is the sealed xenon pressure of 100 Torr.
The lamp life is assumed to be 100%, and the values are shown in relative values. As can be seen from the figure, increasing the amount of titanium oxide deposited dramatically extends the life. When observing the filament of a lamp that has reached the end of its life, the amount of titanium oxide deposited is 0.0.
There was almost no remaining electron emitting material in the case where the concentration exceeded 5B/ci. This condition was close to that of a filament in a lamp with a sealed gas pressure of 50 Torr or more, which was not coated with titanium oxide. Also, according to other similar experiments,
It was found that krybton shortens lifespan more than xenon. In general, rare gases have extremely low reactivity and are called inert gases, and it is said that this tendency becomes stronger as the atoms become smaller. However, in the experiments conducted by the inventors, it was found that smaller atoms actually tend to react more easily in plasma. This is because the ionization level of krypton is higher than that of xenon, so the electron energy during discharge is higher for krypton, which seems to accelerate the reaction. Similarly, for example, when 100% xenon gas and 10% xenon and 90% neon gas were sealed at the same pressure, the latter had higher electron energy and higher brightness, but had a shorter lifespan. Table 1 shows some experimental examples. Table 1 Specification A: No reflective film, only phosphor is fully coated, filled with gas (Xe: 10%, Ne: 90%) Filled pressure: 1. QTorr B: Reflection film, phosphor aperture filling gas composition (Kr: 10%, Ne: 90%) Filling pressure 1.0 Torr Table 1 shows aluminum oxide. As silicon oxide, Aluminum Oxide C manufactured by Degussa was used, but it was not only ineffective but also tended to shorten the lifespan. This is thought to be due not only to the incomplete function of the isolation membrane, that is, the glass shielding, but also to the fact that during baking, these fine particles scratched the inner surface of the glass bulb, exposing impurities (residues) in the glass. Note that forming a titanium oxide film on the inner surface of a glass bulb is known, for example, in Japanese Patent Publication No. 36-7240 and Japanese Patent Application Laid-open No. 5
It is disclosed in Japanese Patent No. 0-35967 and is well known. However, these are intended to suppress the reaction between the conductive film formed on the inner surface of the glass bulb and mercury. On the other hand, JP-A-52-93184 describes a method for suppressing the precipitation of sodium in glass and preventing the reaction between this sodium and mercury. In this way, all of the conventional titanium oxide films mentioned above suppress the reaction with mercury and improve the luminous flux. There is no suggestion that the reaction between the gas and rare gas ions can be suppressed and the life characteristics can be significantly improved. [Effects of the Invention] As explained above, in this invention, the N film is provided on the inner surface of the glass bulb that surrounds the solar column, thereby suppressing the reaction between the luminescent gas and the residue in the glass bulb that would cause cleanup. It can extend the lifespan. Therefore, it has the effect of significantly improving brightness and efficiency without impairing lifespan.

[Brief explanation of drawings]

Figure 1 is a partial cross-sectional view showing one embodiment of the present invention, and Figure 2 is a life characteristic diagram of a low-pressure rare gas discharge lamp using a titanium oxide film. In the figure, (1) is a glass bulb, L2) is a septum NIB
! (Titanium oxide film) ． (3) is a phosphor. (6) is a filament.

Claims (2)

[Claims] (1) In a bulb that seals rare gas as a luminous gas in a bulb and utilizes the light emitted by these gases through discharge, an isolation film from the discharge space is provided on at least the portion surrounding the positive column on the inner surface of the bulb. Characteristic low pressure rare gas discharge lamp. (2) The isolation film is a titanium oxide thin film (TiO_2) with translucent properties formed by thermally decomposing tetrabutyl titanate.
) The low-pressure rare gas discharge lamp according to claim (1).