JPH07161338A - Fluorescent lamp - Google Patents

Abstract

PURPOSE:To reduce the usage of expensive rare earth phosphor. CONSTITUTION:In a fluorescent lamp, in which a light-transmitting ultraviolet ray reflecting layer is formed between a glass bulb 1 and a phosphor layer 2, the ultraviolet ray reflecting layer is formed of magnesium oxide having average particle size of 0.5-5mum, and the phosphor layer is formed of rare earth phosphor having average particle diameter of 1.5-4mum. The ultraviolet ray reflecting layer is coated by 0.7-5mg/cm<2> in thickness and the phosphor layer by 0.5-3mg/cm<2> in thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION This invention relates to a fluorescent lamp using a rare earth fluorescent material, and in particular, an ultraviolet reflecting layer is interposed between the inner surface of the glass bulb and the fluorescent material layer to greatly reduce the amount of expensive rare earth fluorescent material used. The present invention relates to a highly efficient and high color rendering fluorescent lamp.

[0002]

2. Description of the Related Art Recently, in pursuit of a comfortable living environment and a light source that is easy on the eyes, a three-wavelength fluorescent lamp using a rare-earth fluorescent material, which is expensive but high in efficiency and color rendering, has been put into practical use. Has been done.

FIG. 1 shows a schematic structure of this three-wavelength type fluorescent lamp. Reference numeral 1 denotes a glass bulb having a phosphor layer 2 formed on the inner surface thereof and not shown in the glass bulb 1. Is a normal straight tube fluorescent lamp in which mercury or a rare gas is sealed and the electrodes 3 are sealed at both ends.

In the phosphor layer 2, for example, europium-activated calcium barium magnesium chlorophosphate phosphor having an emission peak near 480 nm, cerium having an emission peak near 540 nm, terbium-activated lanthanum phosphate phosphor, and around 610 nm. A europium-activated yttrium oxide phosphor having an emission peak has been used.

As described above, in the three-wavelength fluorescent lamp, the rare earth phosphor emits a narrow band light, and the desired chromaticity point can be easily obtained by changing the compounding ratio of the phosphors of the three colors used. Compared with fluorescent lamps that use calcium halophosphate phosphors that have been commonly used in the past (hereinafter referred to as ordinary fluorescent lamps), high efficiency, high color rendering, and characteristics with less luminous flux attenuation and discoloration can be obtained. It has been used in various fields such as general household use and factory lighting.

By the way, in the three-wavelength fluorescent lamp having such excellent characteristics, since the rare earth phosphor is extremely expensive as compared with the calcium halophosphate phosphor, the unit price of the product is high and the three-wavelength fluorescent lamp of the above It was a major factor that hindered its spread.

Therefore, an expensive fluorescent substance and an inexpensive fluorescent substance are mixed to form a mixed fluorescent substance layer, or an expensive fluorescent substance layer and an inexpensive fluorescent substance layer are stacked to form an expensive fluorescent substance. Measures have been taken to reduce the amount of body use and lamp costs.

For example, Japanese Patent Publication No. 53-867 discloses a glass bulb in which an expensive phosphor layer and an inexpensive phosphor layer are laminated on the inner surface of the glass bulb. However, compared with the method in which the mixed phosphor layer is formed by a single layer,
It is bright and uses a small amount of expensive phosphor, and although it is quite economical, the individual chromaticity points work together to produce the desired chromaticity point and light output, so that chromaticity point There is a problem that it is difficult to control the total luminous flux and color rendering.

Therefore, the present applicant has filed Japanese Patent Application Laid-Open No. 63-2944.
According to Japanese Patent Laid-Open No. 1-58, in a UV-reflecting fluorescent lamp in which a light-transmitting UV-reflecting layer and a phosphor layer are sequentially formed on the inner surface of a glass bulb, the phosphor layer has a particle size of 1.5
An application was made for an ultraviolet-reflecting three-wavelength fluorescent lamp in which a rare-earth phosphor having a small particle size of 4.0 μm was applied to significantly reduce the amount of rare-earth phosphor used.

In the ultraviolet reflective fluorescent lamp, ultraviolet rays that have passed through the phosphor layer and have not been used to excite the phosphor are reflected by the ultraviolet reflective layer and excite the phosphor layer again, so that the utilization efficiency of ultraviolet rays is improved. The luminous efficiency of the lamp is improved.

In the ultraviolet reflecting type three-wavelength type fluorescent lamp, the particle size of the rare earth phosphor is set to 1.5 to 4 .mu.m, which is smaller than the particle size used conventionally, so that the light emitting layer has a uniform coating weight. Since it is formed densely, the light transmittance is reduced. Therefore, even if the coating weight of the phosphor layer is reduced, it is possible to improve the defect in appearance (thin film appearance) in which the electrode or stem at the bulb end is seen through when the fluorescent lamp is turned on. Therefore, the usage amount of the rare earth phosphor is reduced within a range commensurate with the improvement of the luminous flux, and the usage amount of the expensive rare earth phosphor is reduced by about 40% as compared with the case where the ultraviolet reflection layer is not formed. is there.

[0012]

However, the above-mentioned three-wavelength fluorescent lamp constructed so that the amount of phosphor used can be reduced by 40% in this way is less expensive than the calcium halophosphate phosphor in which the price of rare earth phosphor is general. It is extremely expensive, about 20 times, and further cost reduction is required to spread the three-wavelength fluorescent lamp. Even if a slight reduction in illuminance is allowed, the amount of expensive rare earth phosphor used will be further increased. Reduction was a top priority.

Therefore, the present inventors wondered if the amount of rare earth phosphor used in the above-mentioned three-wavelength fluorescent lamp could be reduced by forming the ultraviolet reflection layer in a thick film. That is, it is expected that the thin film appearance defect caused by the reduction of the coating weight of the phosphor layer, through which the electrode is seen, will be eliminated by forming the ultraviolet reflective layer in a thick film, and that it will be caused by the reduction of the coating weight of the phosphor layer. It is intended to cope with the decrease in the amount of light caused by improving the reflection characteristics by forming the film thickness of the ultraviolet reflection layer.

However, in the conventional three-wavelength fluorescent lamp, there is no idea that the UV reflection layer prevents the see-through of the electrode or the stem at the bulb end of the fluorescent lamp, and the UV is reflected, and the visible light passes through it exclusively. Therefore, the ultraviolet reflection layer is formed as an extremely thin translucent film, and the ultraviolet reflection material has a particle size of 30.
Ultrafine particles of alumina or magnesium oxide having a particle size of ˜50 mμm have been used.

Therefore, in order to coat the ultraviolet reflective layer in a thick film, it is necessary to prepare an ultrafine particle reflective material in a high-concentration dispersion or to apply it twice or more. Easily aggregated, and the coating operation was extremely difficult. Further, the latter has a problem that the coating process is complicated.

Therefore, the present invention solves the problem of poor appearance of the thin film in which the electrode or stem at the bulb end is seen through when the ultraviolet reflective layer of the above-mentioned three-wavelength fluorescent lamp is formed as a thick film.
Moreover, it is an object of the present invention to provide a three-wavelength type fluorescent lamp in which the illuminance of the lamp is maintained within a practical range and the amount of expensive rare earth phosphor used can be reduced as much as possible.

[0017]

Therefore, the fluorescent lamp of the present invention is a fluorescent lamp in which a transparent ultraviolet reflecting layer and a phosphor layer are sequentially formed on the inner surface of a glass bulb.
The ultraviolet reflection layer is made of magnesium oxide having an average particle size of 0.5 to 5 μm, the phosphor layer is made of a rare earth phosphor having an average particle size of 1.5 to 4 μm, and the ultraviolet reflection layer is made to be 0.7 to 5 m.
g / cm ² , and the phosphor layer is 0.5 to 3 mg / cm ² .

[0018]

The ultraviolet reflecting layer is formed by coating magnesium oxide having an average particle size of 0.5 to 5 μm, which has a larger particle size than before, on a thick film having a coating weight of 0.7 to 5 mg / cm ² . The light-transmitting property of the UV-reflecting layer is lowered, and the UV-reflecting layer having the lowered light-transmitting property and a phosphor having a small particle size with an average particle size of 1.5 to 4 μm are used to suppress the light-transmitting property. The phosphor layer prevents the see-through of electrodes and stems during lighting,
The coating weight of the phosphor can be reduced. In addition, since the UV reflective layer is formed in a thick film, better UV reflective properties are obtained, the reduction of the luminous flux due to the reduction of the coating weight of the phosphor is considerably prevented, and the decrease in brightness is kept within the practical range. It is possible to reduce the usage amount of. Also,
Since the particle size of magnesium oxide is set to 0.5 μm or more, which is larger than that of the conventional reflecting material, there is no problem such as aggregation of the dispersion liquid, and the coating operation can be extremely simple. Further, since the particle size of magnesium oxide is set to 5 μm or less, a fluorescent lamp having a high film strength can be obtained, and a fluorescent lamp having a good appearance without peeling of the fluorescent film in the lamp manufacturing process can be obtained.

[0019]

EXAMPLES First, an ultraviolet reflecting material for forming an ultraviolet reflecting layer was selected from known reflecting materials, particularly one suitable for a three-wavelength fluorescent lamp by the following experiment for selecting an ultraviolet reflecting material.

That is, aluminum oxide, titanium oxide, zirconium oxide, zinc oxide, and magnesium oxide are taken as the ultraviolet reflecting material, and coating liquids are respectively mixed so as to obtain an appearance in which the electrodes and the stem are not seen through.
A mg / cm ² ultraviolet reflective layer was formed. Then, a phosphor layer is coated on these ultraviolet reflective layers to manufacture a 20 W straight tube fluorescent lamp, and the thick film appearance in which the electrodes and the stem at the bulb end are not seen through when the lamp is lit is confirmed, and the three-wavelength fluorescent lamp is also observed. The total luminous flux after 100 H lighting and the color rendering index, which are required for the characteristic standards of the lamp, were measured, and the compatibility with the JIS standard was evaluated. Furthermore, the color shift during lighting was also evaluated. In addition, as a comparative sample, a sample using the ultrafine alumina of 50 mμm disclosed in the above-mentioned JP-A-63-29441 was simultaneously prepared as a comparative sample, and a comparison test with this was performed, and the results of Table 1 were obtained. .

In this experiment, the particle size of each reflecting material used in the ultraviolet reflecting layer is about 1 μm on average, as noted from the experience of past preparation of dispersion liquid of the ultraviolet reflecting material and difficulty of coating work. The particle size was set, and the specific gravity and viscosity of the dispersion were adjusted by trial and error to obtain a coating weight of ^{2 to 3} mg / cm ² , and the coating was applied. Further, the phosphor layer has an average particle size of about 3 to 4 μm,
Similar to the phosphor disclosed in JP-A-3-29441, a tri-color rare earth phosphor having a relatively small particle size was used, and the phosphor coating weight was 1.5 mg / cm ² .

[0022]

[Table 1]

From Table 1, No.
Since each sample of No. 5 used a large particle size for the reflective material, it was possible to easily obtain a good thick film appearance in which the electrode or stem at the valve end was not seen through. However, the samples other than No. 5 magnesium oxide had a large color shift in the 2000H lighting test, and could not be practically adopted.
Further, the total luminous flux ratio and the average color rendering index of titanium oxide were at levels that cannot be adopted.

On the other hand, the No. 5 magnesium oxide sample is within the standard in the total luminous flux ratio after 100H, which is slightly inferior to 97% of the comparative sample, and the color shift is good. In particular, the unexpectedly favorable effect that the color rendering index Ra was improved by 3 compared to the comparative sample was obtained.

Next, from the result of the above selection experiment of the reflective material, in the present invention, magnesium oxide was selected as the reflective material of the ultraviolet reflective layer of the three-wavelength fluorescent lamp, and the applicable magnesium oxide particle diameter was selected. In order to set, the following selection experiment of the particle size of magnesium sulphate was conducted mainly on the dispersibility of the coating liquid of the reflecting material and the film strength after coating the phosphor layer.

That is, the particle size of magnesium oxide is 0.1 to 6
In the range of μm, the coating liquid of these magnesium oxides is applied in the same manner as in the above experiment to form a phosphor layer on these reflective layers under the same coating conditions as in the above experiment,
20 W straight tube fluorescent lamps were manufactured and the total luminous flux was measured. FIG. 2 shows the results of the total luminous flux ratio, the dispersibility of the coating liquid during film formation, and the film strength of the phosphor layer.

From this experiment, it was found that the magnesium oxide coating solution having a particle size of 0.3 μm was agglomerated shortly after the production of the coating solution, and it was not possible to stably form the ultraviolet reflecting layer having a uniform coating on the glass bulb. On the contrary, the particle size is large 6.
The 0 μm magnesium oxide coating solution had a weak adhesion strength to the glass bulb, and a film drop failure occurred due to shock during the lamp manufacturing process. When the particle size is in the range of 0.5 to 5.0 μm, there is no problem in the dispersibility of the coating solution and the film strength, and the total luminous flux is slightly larger when the particle size is smaller, but good results are obtained. There is.

Next, in order to examine the relationship between the coating thickness of the ultraviolet reflecting layer, the poor appearance of the thin film, and the total luminous flux of magnesium oxide whose particle size is selected as described above, the following magnesium oxide coating weight is used. The experiment was done.

That is, the particle size of magnesium oxide is 2.0 μm.
The coating weight was fixed to 0.1 mm, the coating weight was varied in the range of 0.1 to 6.0 mg / cm ² to form a magnesium oxide UV reflection layer coating, and a phosphor layer was formed on this coating under the same coating conditions as in the above experiment. 20 W straight tube fluorescent lamps were manufactured and the film thickness appearance and total luminous flux were measured. FIG. 3 shows the results of the total luminous flux ratio and the thick and thin appearance.

From this experiment, the thin film appearance has a coating weight of 0.7.
mg / cm²Above, the electrodes and stem at the valve end are not visible.
A good thick film appearance was obtained. However, the applied weight is 0.
1 mg / cm²In that case, the electrodes and stem at the valve end are seen through.
The commercial appearance was not obtained. Also, the total luminous flux is acid
Magnesium chloride coating weight is 0.7 to 3.0 mg / cm ²
Is about the same, but the coating weight is 0.4 mg / cm
²Below and 5.0 mg / cm²The above are obviously reduced
I will do it. The applied weight is 6.0 mg / cm.²Above
As the total luminous flux decreases, the coating process is performed during the phosphor layer firing process.
It becomes difficult to remove organic substances from the cloth liquid, and the starting characteristics of the lamp
There was a problem that the quality was damaged. Therefore, oxidation
Magnesium coating weight is large for film thickness appearance and total luminous flux
0.7 to 5.0 mg / cm to influence²The degree is
It was confirmed to be within the applicable range.

On the other hand, since the coating thickness of the phosphor layer is also closely related to the total luminous flux and the thin film appearance, the coating weight of the phosphor layer which is a combination of both the coating weight of the phosphor layer and the coating weight of magnesium oxide is An experiment was conducted.

That is, the ultraviolet reflection layer has a coating weight of 0.1, 0.7.
, 5.0 mg / cm ² in 3 stages, and for comparison purposes, 4 types were added in addition to those without forming an ultraviolet reflection layer. Further, the phosphor layer was applied in five stages of 1, 2, 3, 4, and 5 mg / cm ² , and the appearance was visually checked and the total luminous flux was measured. The results shown in FIG. 4 were obtained. In this experiment, the particle size of magnesium oxide was 2.0 in the range of good dispersibility of the coating solution.
The average particle size of the phosphors was set to 2.7 μm and the particle size of the phosphor was sufficiently smaller than 5 μm.

From this experiment, the coating weight of the ultraviolet reflecting layer was
With 0.1 mg / cm ² , the total luminous flux can be reduced by 2%, for example, and the phosphor coating weight can be reduced by 40% as shown by the solid line arrow, as compared with the case where the ultraviolet reflection layer is not formed. it can. However, the phosphor coating weight is 3 mg
When the value was lower than / cm ² , the appearance was poor. on the other hand,
Of what coating weight of 0.7 and 5.0 mg / cm ² of UV-reflecting layer, without the appearance defect occurs also decreases the phosphor coating weight in 1 mg / cm ^2, thus, allow 5% decrease in total flux By doing so, the phosphor coating weight can be greatly reduced to 70% and 80%, respectively, as indicated by the dotted arrow.

In order to confirm the characteristics of these prepared fluorescent lamps, the color rendering index was evaluated for the one in which the coating weight of magnesium oxide in the above experiment was set to 0.7 mg / cm ² and the one in which the ultraviolet reflecting layer was not formed. Ra and triple wavelength radiant flux ratio RT were measured. The result is shown in FIG.

From the figure, the color rendering index Ra and the three-wavelength radiant flux ratio RT both decrease as the coating weight of the phosphor decreases. In particular, the color rendering index Ra is the phosphor coating weight.
When the amount is reduced by 3 mg / cm ² or more, the value drops sharply, and those without the UV reflection layer deviate from the permissible range, but those with the magnesium oxide reflection layer do not show such deviation and show good color rendering properties. There is.

[0036]

As described in detail above, according to the present invention,
The rare earth phosphor constituting the phosphor layer has a small particle size with suppressed light transmission, and the ultraviolet ray reflective layer contains 0.7 to 5 mg / magnesium oxide having an average particle size of 0.5 to 5 μm.
By forming it to have a size of cm ² , even if the coating weight of the phosphor layer is reduced, it is possible to prevent see-through of the electrode and the stem. Also, by forming the reflective layer in a thick film, the reflection characteristics of ultraviolet rays are enhanced and the decrease in total luminous flux is mitigated, while keeping the total luminous flux within the practical range, the amount of expensive rare earth phosphor used can be minimized. Can be reduced. Therefore, the lamp cost can be significantly reduced, and the three-wavelength fluorescent lamp can be popularized. Further, a high average color rendering index Ra and triple wavelength radiant flux ratio RT, which are characteristics of the rare earth fluorescent substance, can be obtained, and an excellent triple wavelength fluorescent lamp can be provided.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view of a three-wavelength fluorescent lamp to which the present invention is applied.

[Fig. 2] Experimental data diagram in which the particle size of magnesium oxide in the ultraviolet reflective layer is varied.

FIG. 3 is an experimental data diagram in which the coating weight of magnesium oxide on the ultraviolet reflective layer is changed.

FIG. 4 is an experimental data diagram in which the phosphor coating weight of the phosphor layer is changed.

5 is a color rendering evaluation index Ra and a three-wavelength radiant flux ratio RT characteristic diagram of the partial fluorescent lamp of FIG.

Front Page Continuation (72) Inventor Koji Nomura 1-42 Jomi, Chuo-ku, Osaka-shi, Osaka NEC Home Electronics Co., Ltd.

Claims (1)

[Claims] 1. A fluorescent lamp in which a light-transmitting UV-reflecting layer and a phosphor layer are sequentially formed on the inner surface of a glass bulb, wherein the UV-reflecting layer has an average particle size of 0.5 to 5 μm and is composed of magnesium oxide and fluorescent light. Body layer has an average particle size of 1.5 to 4 μm
Of the rare earth phosphor, and the ultraviolet reflection layer is 0.7 to
Fluorescent lamp 5 mg / cm ^2, the phosphor layer is characterized by a 0.5-3 mg / cm ^2.