JPH11111228A - Fluorescent lamp - Google Patents

Abstract

(57) [Summary] An object of the present invention is to provide an ultraviolet light-emitting fluorescent lamp which does not reduce both the luminous flux maintenance factor and the initial radiant flux. A fluorescent lamp according to the present invention has a translucent airtight container 1 in which discharge is generated and in which mercury and a rare gas are sealed; an average film thickness of 10 to 30 nm, and a coverage of 75.
% Of yttrium oxide (Y ₂ O ₃ ) is formed on the inner surface side of the hermetic container mainly using a lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) whose surface is coated with fine particles. And a phosphor layer 6 provided. The protective layer of the phosphor layer 6 has a weight ratio of a protective film made of yttrium oxide (Y ₂ O ₃ ) of 0.3 to 0.3.
The coating may be performed so that the coating rate is 1.5 wt% and the coating rate is 75% or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fluorescent lamp that emits ultraviolet light.

[0002]

2. Description of the Related Art Lead-activated barium silicate phosphors (BaSi
₂ O ₅ : Pb) has a wavelength of 254 which is an emission line of mercury (Hg).
It is excited by ultraviolet light of nm, and efficiently emits ultraviolet light having a wavelength of 351 nm as a peak.

[0003] Lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) is mainly used in an ultraviolet light emitting fluorescent lamp generally called a black light. Such an ultraviolet fluorescent lamp has been used as a light source for health rays or a light source for decoration. In recent years, its use as a light source for photocatalytic activity has been studied.

Incidentally, a fluorescent lamp using this lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) has a relatively higher luminous flux maintenance rate than a fluorescent lamp using a three-wavelength light emitting phosphor. It is known to be low. The reason is that the lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) reacts with and absorbs mercury (Hg), and the mercury (H
g) It is considered that the amount decreases.

As means for improving the luminous flux maintenance factor of a fluorescent lamp, for example, as described in JP-A-9-504138, the surface of the phosphor fine particles is made of a metal oxide of yttria (Y) or aluminum (Al). A method of coating is known.

[0006] Such a coating treatment is performed, for example, by using a europium-activated barium aluminate phosphor (BaMg ₂ Al).
It is described that the luminous flux maintenance factor is improved when applied to ₁₆ O ₂₇ : Eu). It is considered that this is because the amount of mercury (Hg) adsorbed on the phosphor is significantly reduced by the metal oxide coating treatment.

[0007]

However, since the film thickness of the above-mentioned conventional metal oxide is as large as 25 to 100 nm, when coating with, for example, yttrium oxide (Y ₂ O ₃ ), mercury (Hg) is reduced. Ultraviolet rays near the wavelength of 185 nm, which are bright lines, are slightly absorbed.

In particular, a lead-activated barium silicate phosphor (Ba)
Si ₂ O ₅ : Pb) has a wavelength of 25 which is an emission line of mercury (Hg).
In addition to the ultraviolet light of 4 nm, it is also excited by ultraviolet light of a wavelength of 185 nm, so that the ultraviolet radiation flux at the time of initial lighting is significantly reduced.

An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an ultraviolet light-emitting fluorescent lamp in which neither the luminous flux maintenance factor nor the initial radiant flux is reduced.

[0010]

According to a first aspect of the present invention, there is provided a fluorescent lamp comprising: a light-transmitting airtight container in which a discharge is generated and in which mercury and a rare gas are sealed;
nm, yttrium oxide with a coverage of 75% or more (Y
A phosphor layer mainly formed of a lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) having a protective film made of ₂ O ₃ ) coated on the surface of the fine particles; It is characterized by having.

A fluorescent lamp according to a second aspect of the present invention is a translucent airtight container in which discharge is generated and in which mercury and a rare gas are sealed; and a lead-activated barium silicate phosphor (BaSi _2).
O ₅ : Pb) fine particles are coated with a protective film made of yttrium oxide (Y ₂ O ₃ ) so that the weight ratio is 0.3 to 1.5 wt% and the coverage is 75% or more. A phosphor layer mainly composed of barium silicate phosphor (BaSi ₂ O ₅ : Pb) fine particles formed on the inner surface side of the hermetic container.

In the claims 1, 2 and the following claims, the terms are defined as follows, and well-known structures and means can be applied to those not particularly defined.

The transparent airtight container is made of soda lime glass,
It is formed of a translucent material such as translucent ceramics in addition to a glass material such as borosilicate glass and has a discharge space. Containers are not limited to straight pipes, but are ring-shaped, U-shaped,
It may be shaped like a letter, an H, a saddle, a flat plate, or the like.

In the container, mercury (Hg) and a rare gas are sealed as a discharge medium. As a rare gas, argon (Ar), neon (Ne), krypton (Kr), or the like is sealed at a pressure of several Torr. Further, xenon (Xe) is mixed with mercury (Hg) to form xenon (Xe).
The phosphor may be excited by ultraviolet light having a wavelength of 174 nm, which is the emission line of e).

The means for generating a discharge may be a hot-cathode or cold-cathode internal electrode provided inside the container, an external electrode provided outside the container, an excitation coil for applying a high-frequency electromagnetic field, or the like. It is possible.

The phosphor constituting the phosphor layer is mainly composed of lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) fine particles, but a visible light emitting phosphor or another phosphor is used. You may mix.

The protective layer is made of yttrium oxide (Y ₂ O ₃ ), has a coverage of 75% or more, an average thickness of 10 to 30 nm, or a weight ratio of 0.3 to 1.5 wt.
% Of the lead-activated barium silicate phosphor (BaSi
₂ O ₅ : Pb) The fine particle surface is coated. For example, it indicates that it is coated with the yttrium oxide 0.3~1.5g per fluorescent fine particles 100g (Y ₂ O _3).

The protective film is formed by dispersing ultrafine particles of yttrium oxide (Y ₂ O ₃ ), and is coated with an yttrium solvent such as yttrium nitrate (Y ₂ (NO ₃ )) or an organic metal solution. May be a continuous film formed.

The coverage is defined by calculating, on average, the ratio of the surface area of the protective layer to the apparent surface area of the phosphor fine particles observed with an electron microscope.

The average film thickness is defined by measuring the thickness of the protective layer by observing the fine phosphor particles with an electron microscope, and defining the average value of the film thickness.

Incidentally, in addition to observation by an electron microscope, ES
The analysis may be performed by a device such as CA or SIMS.

The weight ratio is defined by the ratio of the total weight of the protective layer to the total weight of the phosphor fine particles, and the weight of the protective film is determined from the weight of the yttrium oxide (Y ₂ O ₃ ) forming material in the coating treatment of the phosphor fine particles. Converted.

In the first and second fluorescent lamps, the lead-activated barium silicate phosphor (BaSi ₂ O ₅ : P
Since the fine particles of b) are coated with a protective film made of yttrium oxide (Y ₂ O ₃ ) under suitable conditions, mercury (Hg) is less likely to be absorbed by the phosphor, so that a decrease in the UV intensity maintenance rate is suppressed. At the same time, ultraviolet rays emitted by mercury are hardly absorbed by the protective film, so that the initial radiant flux does not greatly decrease.

A third aspect of the present invention is the fluorescent lamp according to the first or second aspect, wherein the light-transmitting airtight container is made of black light blue glass.

A black light can be constituted by the fluorescent lamp of the third aspect.

According to a fourth aspect, in the fluorescent lamp according to the first or second aspect, the material of the light-transmitting airtight container is iron oxide (Fe).
It is a soda lime glass having a content of ₂ O ₃ ) of 500 ppm or less.

The fluorescent lamp according to the present invention is characterized in that even if soda lime glass, which is easy to manufacture and inexpensive, is used for the container, iron oxide (Fe
_Since the content of ₂ O ₃ ) is 500 ppm or less, the wavelength 3
The ultraviolet transmittance of 00 to 400 nm is improved, and the initial radiant flux can be improved.

According to a fifth aspect, in the fluorescent lamp according to any one of the first to fourth aspects, the tube wall load is 500 W / m ^2.
It is characterized by being turned on as described above.

The fluorescent lamp according to claim 5 has a tube wall load of 50.
Lighting at 0 W / m ² or more increases the intensity of ultraviolet rays having a wavelength of 185 nm among emission lines emitted from mercury (Hg), and the ultraviolet rays excite the lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb). This improves the UV radiation flux.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a conceptual diagram showing a straight tube type fluorescent lamp according to an embodiment.

The fluorescent lamp 10 has a rated power of 20 W. Reference numeral 1 denotes a light-transmitting airtight container having a straight tube shape. The container 1 has an outer diameter of 28 mm and a tube length of about 580 mm, and is made of, for example, soda-lime glass. Both ends of the container 1 are sealed by stems 2, 2, and lead wires 3, 3 pass through these stems 2, 2 in an airtight manner. Filament electrodes 4 and 4 as means for generating a discharge are attached to the lead wires 3 and 3, and these electrodes 4 and 4 are formed in a double coil by a tungsten wire or the like, and an emitter (not shown) is applied. ing.

Reference numeral 6 denotes a phosphor layer formed on the inner surface of the container 1, which is a lead-activated barium silicate phosphor (BaSi ₂ O ₅ : P).
b) is mainly constituted. The surface of the fine particles of the phosphor is coated with a protective film made of yttrium oxide (Y ₂ O ₃ ).

The phosphor layer 6 is formed by coating a phosphor coated with a protective film with a mixture of butyl acetate or water and a binder on the inner surface of the container 1, drying and firing.

The coating treatment of the phosphor fine particles will be described in detail. First, 1.5 to 7.5 g of Y ₂ (NO ₃ ) was added to 500 g of a lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) having an average particle size of 11 μm. Thereafter, the phosphor is washed and dried, so that yttrium oxide (Y ₂ O ₃ ) is coated as a protective film.

FIG. 2 is a graph showing an ultraviolet intensity maintaining ratio of the fluorescent lamp of the present embodiment. In addition, the graph shows the present embodiment as a, the fluorescent lamp using a conventional lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) without a protective film coating treatment as Comparative Example b, Radiant flux value 1
The change in the relative value is set to 00%.

In Comparative Example b, when 4000 hours (h) have elapsed since the start of lighting, the rate is 60% or less, whereas in the present embodiment a, about 70% or more is high after 4000 hours (h). Values, indicating that the life characteristics have been improved.
This is considered to be because mercury (Hg) and mercury oxide (HgO) were suppressed from adsorbing to the phosphor by the coating treatment of the protective film.

Next, the relationship between the amount of addition of yttrium oxide (Y ₂ O ₃ ) to the phosphor as a protective film (weight ratio: wt%) and the initial ultraviolet radiation flux is shown in Table 1.
Shown in Here, the initial radiant flux is a measured value immediately after the start of lighting (0 hour).

[0039]

[Table 1] As can be seen from this table, yttrium oxide (Y ₂ O ₃ )
The initial radiant flux decreases as the addition amount of
Up to t%, the initial radiant flux of the lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) which is not coated can be suppressed to 95%.

When the addition amount is less than 0.3 wt%, it is close to the strength retention rate of the comparative example without coating treatment, and when it is 0.3 wt% or more, the strength retention rate of the embodiment a of FIG. 1 is also satisfied. Was confirmed, the addition amount was 0.3 to 1.5 wt.
%.

Further, in order to obtain the above-mentioned UV intensity maintaining ratio, the average thickness of the protective film must be 10 nm or more.
In the case of a conventional large phosphor having an average thickness of the protective film exceeding 30 nm, ultraviolet light having a wavelength of 185 nm is absorbed by the protective film. Lead activated barium silicate phosphor (Ba)
Since Si ₂ O ₅ : Pb) is also excited by ultraviolet rays having a wavelength of 185 nm, the initial radiant flux is reduced when the ultraviolet rays having a wavelength of 185 nm are absorbed by the protective film. Therefore,
The average thickness of the protective film is preferably in the range of 10 to 30 nm.

The fluorescent lamp tube wall load was 500 W /
When it is larger than m ^2, the emission line at a wavelength of 254 nm is reduced due to an increase in the mercury vapor pressure, and the wavelength is 185 nm.
The emission line does not change much, resulting in a wavelength of 185
/ 254 nm ratio increases. Therefore, a fluorescent lamp coated with a protective film of yttrium oxide (Y ₂ O ₃ ) that does not absorb much ultraviolet light having a wavelength of 185 nm as in the present embodiment has a condition that the tube wall load becomes 500 W / m ² or more. This effectively suppresses a decrease in the ultraviolet radiation flux.

Further, for example, even with an emission line of xenon (Xe) having a wavelength of about 185 nm (wavelength of about 174 nm), since this phosphor emits ultraviolet light well, xenon (Xe) may be sealed in the container 1.

[0044]

According to the fluorescent lamp of the present invention, the fine particles of the lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) are formed under suitable conditions by a protective film made of yttrium oxide (Y ₂ O ₃ ). Since the coating treatment is performed, mercury (Hg) is less likely to be absorbed by the phosphor, so that the decrease in the ultraviolet ray intensity maintenance rate is suppressed, and the ultraviolet rays emitted by the mercury are hardly absorbed by the protective film. Is not greatly reduced.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a straight tube fluorescent lamp according to an embodiment of the present invention.

FIG. 2 is a graph showing an ultraviolet intensity maintenance ratio of the fluorescent lamp according to the embodiment;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Translucent airtight container, 6 ... Phosphor layer, 10 ... Fluorescent lamp.

Claims (5)

[Claims] 1. A translucent airtight container in which a discharge is generated and in which mercury and a rare gas are sealed; a means for generating a discharge in the container; and an average film thickness of 10 to 30 n.
m, yttrium oxide (Y ₂ O ₃ ) with a coverage of 75% or more
And a phosphor layer mainly formed of a lead-activated barium silicate phosphor (BaSi ₂ O ₅ : Pb) having a protective film made of fine particles coated on the surface of the fine particles and formed on the inner surface side of the hermetic container. A fluorescent lamp. 2. A translucent airtight container in which a discharge is generated and in which mercury and a rare gas are sealed; means for generating a discharge in the container; and a lead-activated barium silicate phosphor (BaSi _2). O ₅ : Pb) fine particles are coated with a protective film made of yttrium oxide (Y ₂ O ₃ ) at a weight ratio of 0.3 to 1.5 w
t%, the coating treatment is performed so that the coverage is 75% or more,
This lead-activated barium silicate phosphor (BaSi ₂ O ₅ : P
b) a phosphor layer mainly composed of fine particles and formed on the inner surface side of the hermetic container. 3. The fluorescent lamp according to claim 1, wherein the translucent airtight container is made of black light blue glass. 4. The material of the transparent airtight container is iron oxide (Fe _2
3. The fluorescent lamp according to claim 1, wherein the content of O ₃ ) is soda lime glass having a content of 500 ppm or less. 5. The fluorescent lamp according to claim 1, wherein the fluorescent lamp is lit at a tube wall load of 500 W / m ² or more.