JPS6241379B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a so-called ultraviolet-free fluorescent lamp that minimizes ultraviolet radiation.

As shown in Fig. 1, a known non-ultraviolet fluorescent lamp is made by coating titanium oxide as a first layer on the inner surface of a glass tube wall as a substance that absorbs ultraviolet rays and reflects visible light, and then coats titanium oxide as a luminescent material on top of this as a first layer. 2nd phosphor
There were some cases where the coating was applied in more than one layer. That is, the first layer absorbs and blocks mercury emission lines of 313 nm and 365 nm and a portion of the ultraviolet rays emitted from the phosphor layer.

However, these conventional non-UV fluorescent lamps had the following drawbacks. the first layer is the second
Since it absorbs a considerable amount of ultraviolet rays that have passed through the second layer or higher layers (phosphor layer) and visible light emitted from the second layer or higher layers, energy loss is large and luminous efficiency is low. The titanium oxide used in the first layer changes color during lighting, resulting in a large drop in luminous flux. Since the impure gas occluded in the titanium oxide used in the first layer is brought into the lamp, there are drawbacks such as the phenomenon that the discharge tends to undulate and the starting voltage tends to increase.

An object of the present invention is to provide a non-ultraviolet fluorescent lamp that can improve the above-mentioned drawbacks and improve productivity.

As a result of various experiments, the inventors of this invention determined that titanium oxide is a substance that reflects visible light and absorbs ultraviolet rays, and that this titanium oxide was used at a concentration of 1.2 mg/cm ^{2 .}
When an alkaline earth metal borophosphate phosphor defined by the chemical composition formula below is used as at least one of the luminescent materials on a layer formed with a coating amount of less than It has been found that the amount used can be kept to a minimum, and as a result, the above-mentioned drawbacks can be improved.

Here, the alkaline earth metal borophosphoric acid phosphor was previously proposed by some of the inventors of the present invention in an unpublished patent application, and is m(Sr ₁ -x-y-p Bax Cay EupO)・(1-n)P ₂ O ₅・nB ₂ O ₃ (0≦x≦0.5, 0≦y≦0.2, 0.001≦p
≦0.15, 1.75≦m≦2.30, 0.05≦n≦0.23)
It is defined by This phosphor emits blue-green light when excited not only by ultraviolet rays but also by visible blue light, and when used in fluorescent lamps, it is more effective than antimony-activated calcium halophosphate phosphors, which are conventional blue phosphors. Shows extremely high luminous efficiency. It also has the characteristic that the luminous flux decreases little during lamp lighting.

When this borophosphate phosphor contains only strontium as an alkaline earth metal in the host crystal, the emission peak is at about 480 nm, and when it contains a certain amount of barium, the emission peak is slightly extended to about 490 nm. Move to the wavelength side. When calcium is contained, only a slight shift in the luminescence peak is observed if the content is within the above-mentioned limited range.

The content of the alkaline earth metals barium and calcium can be within the above-mentioned limits, but in general, the best results in terms of luminous output are obtained when only strontium or a very small amount of barium or (and) calcium is contained. can be obtained. This is because the luminous output gradually decreases with increasing barium and/or calcium content. In addition, the barium content must not exceed 0.5 in x value, and the calcium content must not exceed 0.2 in y value.
This is because when these values are exceeded, the light emission output decreases significantly.

The europium content p is selected such that 0.001≦p≦0.15. The reason for this is that in this way a phosphor with a large luminous output can be obtained. When the value of p is 0.005 to 0.05, the light emission output becomes extremely large, so a value within this range is particularly preferable.

The values of m and n are 1.75≦m≦2.30, 0.05≦n≦
Should be 0.23. This is because the light emission output becomes small outside this range. The maximum light emission output is obtained when m is 1.90 to 2.10 and n is 0.14 to 0.18, so values within these ranges are particularly preferred.

The borophosphate phosphor described above can be produced as follows. For example, a predetermined amount of alkaline earth metal carbonate or phosphate, boric acid, europium oxide, etc. is mixed as a starting material and fired at a temperature of approximately 1000 to 1200°C in a reducing atmosphere such as N ₂ + H ₂ . If you do, you will get it. For example SrHPO ₄ 1.68 mol, SrCO ₃
The phosphor using 0.28 mol of H ₃ BO ₃ , 0.32 mol _of H 3 BO 3 , and _0.02 mol of Eu ₂ O ₃ as starting materials has an extremely suitable chemical composition 2 (Sr _0.98 Eu _0.02 O)・0.84P ₂ O ₅・0.16 It satisfies B ₂ O ₃ .

Note that this borophosphate phosphor is present in the host crystal.
Be, Mg, Zn, Cd, Mn, Sc, Y, La, Ce,
Elements such as Tb, Pb, Ga, Al, Si, Zv, Ge, and S may be contained in small amounts. However, if the content exceeds 0.5 to 5% (depending on the type of element) based on the total number of alkaline earth metals, europium, phosphorus, and boron, it is not desirable because it will cause negative effects such as a decrease in luminescence intensity. I confirmed that.

The present invention will be explained below with reference to tables and figures.

FIG. 2 shows the reflection spectrum of the borophosphate phosphor in comparison with that of a tetravalent manganese-activated red phosphor and titanium oxide, which have been conventionally used as ultraviolet absorbing materials. It can be seen that this phosphor absorbs ultraviolet and visible blue light in the wavelength range below about 440 nm. In other words, the use of this phosphor serves the same role as titanium oxide used in conventional non-UV fluorescent lamps. Moreover, the borophosphate phosphor has a strong mercury emission line of approximately 330 to 420 nm (365 nm,
This is advantageous because it has a stronger absorption effect at the position where the wavelength (405 nm) exists.

FIG. 3 shows the spectral distribution in the ultraviolet region (300 to 400 nm) of a fluorescent lamp made by directly applying the borophosphate phosphor to a glass tube without using titanium oxide. For comparison, the spectral distribution of a fluorescent lamp made using antimony-activated calcium halophosphate, which is a known representative blue phosphor that exhibits almost no absorption in the ultraviolet region of 300 to 400 nm, is shown on the same scale.
The emission intensities of both curves can be directly compared. Moreover, Hg represents the mercury emission line. It has been found that the borophosphate phosphor used in this invention has the effect of significantly reducing ultraviolet radiation even without the use of ultraviolet absorbing substances.

Due to the ultraviolet control effect of the borophosphate phosphor described above, by using this phosphor, it is possible to reduce the amount of use that has the above-mentioned negative effects on the characteristics of titanium oxide fluorescent lamps by up to about 1. It has been found that it is possible to manufacture a fluorescent lamp that does not emit ultraviolet rays even when the amount is reduced to about /6.

The present invention will be explained below with reference to Examples.

Example: Titanium oxide with a particle size of approximately 0.05μ is applied to the inner surface of a glass tube.
It was coated and baked at a coating weight of 0.51 mg/ _cm ² , and then the next phosphor 2 (Sr _{0.98 Eu 0.02} O), 0.84P ₂ O ₅ , 0.16B ₂ O ₃ 46g (Sr, Mg ) ₃ (PO ₄ ) ₂ : Sn 48g Zn ₂ SiO ₄ : Mn 1g Ca ₁₀ (PO ₄ ) ₆ (F, Cl) ₂ : Sb, Mn (6100K)
A 40 watt straight tube fluorescent lamp with a tube diameter of 32 mm was made by mixing 5 g of the mixture, coating it at a coating weight of 4.5 mg/cm ² , baking it, filling it with a small amount of mercury and a rare gas, and attaching a cap.
This lamp is a high color rendering fluorescent lamp with an average color rendering index R _a of 98 and a color temperature of 5000K. When the ultraviolet rays (300 to 390 nm) of the obtained fluorescent lamp were measured, no ultraviolet rays could be detected.

The spectral distribution of this lamp is shown in FIG. The characteristics of this lamp are luminous efficiency of 62lm/W.92% luminous flux maintenance rate at 1000 hours, which is higher than ordinary fluorescent lamps that are not coated with titanium oxide.
At 1 lm/W, the luminous flux maintenance rate was only 1% lower. That is, there was only a slight adverse effect on the efficiency and luminous flux maintenance rate.

The conventional examples to be compared are as follows. In other words, a fluorescent lamp made by replacing the borophosphate phosphor with the conventional blue phosphor antimony-activated calcium halophosphate must contain 1.2% titanium oxide to prevent ultraviolet rays from being detected.
It was necessary to apply the coating at a coating amount of mg/cm ² or more. Therefore, compared to a fluorescent lamp without titanium oxide coating, the luminous efficiency was 3 lm/W lower, and the luminous flux maintenance rate over 1000 hours was 4% lower.

Furthermore, the occurrence rate of the phenomenon in which the discharge moves in a undulating manner in the fluorescent lamp according to the present invention was 1/100, and that in the comparable conventional fluorescent lamp to which a large amount of titanium oxide was attached was 5/100.

Furthermore, the starting voltage of the fluorescent lamp of the present invention was the same as that of a fluorescent lamp not coated with titanium oxide, whereas that of the fluorescent lamp of the conventional example with a large amount of titanium oxide adhered to was lower than that of a fluorescent lamp not coated with titanium oxide. It was about 4V higher than that.

It will be understood from the above description that in this invention, the greater the amount of the borophosphate phosphor used, the less the amount of titanium oxide used.

It has also been confirmed that similar effects can be obtained even if the luminescent layer containing the borophosphate phosphor is formed into a plurality of layers as the second or higher layer. Furthermore, it was confirmed that the borophosphate phosphor used in the present invention can be used in the same manner as long as it conforms to the above chemical composition formula, since it exhibits a reflection spectrum substantially similar to that shown in FIG.

As explained above, this invention uses titanium oxide as a substance that reflects visible light and absorbs ultraviolet rays, forms a layer of titanium oxide in an amount of less than 1.2 mg/cm ² , and deposits the titanium oxide on this layer. By using the new borophosphate phosphor as part of the luminescent material, it is possible to reduce the amount of UV-absorbing substances such as titanium oxide, which adversely affect the properties of UV fluorescent lamps, thereby reducing the amount of UV-absorbing substances, such as titanium oxide, that adversely affect the properties of UV fluorescent lamps. This study teaches that the disadvantages of fluorescent lamps, such as reduced luminous efficiency, reduced luminous flux, discharge waviness, and increased starting voltage, can be improved.Furthermore, it is possible to improve the formation of a phosphor layer while preventing the peeling of the titanium oxide layer. It also has the advantage of making it easier and improving productivity.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a non-UV fluorescent lamp, Figure 2
The figure shows the reflection spectra of the ultraviolet absorbing substance and the phosphor; FIG. 3 is a diagram showing the ultraviolet absorption effect of the phosphor used in the present invention in a fluorescent lamp in comparison with known phosphors; FIG. 4 is a diagram showing the spectral distribution of the fluorescent lamp according to the embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A first layer consisting of a substance that reflects visible light and absorbs ultraviolet rays is formed on the inner surface of the glass tube wall, and a phosphor that emits light in the visible wavelength range is formed as a main component on top of the first layer. In the fluorescent lamp, the material of the first layer is titanium oxide, and the amount of adhesion thereof is less than 1.2 mg/ ^cm2 , and the material of the first layer is titanium oxide, and the luminescent layer is formed as a second or higher layer. A fluorescent lamp characterized in that the layer contains at least an alkaline earth metal borophosphate phosphor defined by the following chemical composition formula. m(Sr ₁ −x−y−p Bax Cay EupO)・(1−n)・P ₂ O ₅・nB ₂ O ₃ where 0≦x≦0.5, 0≦y≦0.2, 0.001≦p≦
0.15, 1.75≦m≦2.30, and 0.05≦n≦0.23.