JP2006190658A - Fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent lamp in which a phosphor layer is hard to be peeled off while suppressing reduction of brightness. <P>SOLUTION: In the fluorescent lamp having a glass bulb 16 and the phosphor layer 22 formed on an inner face side of the glass bulb 16, the phosphor layer 22 is constituted of a plurality of phosphor particles 24 and a binder 26 which is one to surround and couple the phosphor particles 24 with each other, and in which yttrium oxide and an alkaline earth metal borate are the components. In the case where a total weight ratio of yttrium oxide to the total weight 100 of the fluorescent particles 24 is A and the total weight ratio of the alkaline earth group metal borate is B, A and B are adjusted within a range of 0.1≤A≤0.6 and 0.4≤(A+B)≤0.7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fluorescent lamp, for example, a fluorescent lamp used as a light source of a backlight unit in a liquid crystal display device.

Among the fluorescent lamps, a cold cathode fluorescent lamp in which a phosphor layer is formed on the inner surface side of a tubular glass bulb and a cold cathode is provided as an internal electrode at both ends is suitable for reducing the diameter. For this reason, it is suitably used as a light source of a backlight unit that is required to be thin (downsized).
In addition, the light source application of the backlight unit is particularly required to have an excellent luminance maintenance rate. The main causes of the decrease in luminance over time include phosphor deterioration and mercury consumption. It is believed that phosphor degradation and mercury consumption occur as follows.

Conventionally, the phosphor layer is composed of an infinite number of phosphor particles and a binder made of only CBB (a kind of alkaline earth metal borate) that connects these phosphor particles. . Most of the CBB is spot-attached to the phosphor particles and connects the phosphor particles. For this reason, most of the surface of the phosphor particles is considered to be exposed from the CBB.
The phosphor layer is exposed to the impact of mercury ions generated when the cold cathode fluorescent lamp is turned on. In the case of the conventional phosphor layer described above, the phosphor particles are bombarded with mercury ions at the exposed portion, and the crystal structure thereof changes to a non-light-emitting crystal structure. Some of the mercury ions hitting the phosphor particles and the CBB remain in the phosphor particles and the CBB as they are. As a result, mercury that contributes to ultraviolet light emission is gradually consumed.

  Therefore, Patent Document 1 discloses a fluorescent lamp in which a phosphor layer is formed using yttrium oxide having characteristics capable of withstanding the impact of mercury ions instead of the CBB. Patent Document 1 states that “a phosphor layer is attached to a plurality of phosphor particles and a contact portion (connecting portion) of the phosphor particles, and the surface of the phosphor particles is partially exposed. And the metal oxide (yttrium oxide) ”(in parentheses added by the applicant of the present application). That is, in the phosphor layer of Patent Document 1, the phosphor particles are covered with yttrium oxide at least part of the surface of the connecting portion and the surface other than the connecting portion.

In the phosphor particles of Patent Document 1, the surface other than the connecting portion is covered with yttrium oxide, and the exposed portion is smaller than the above-described conventional phosphor particles. For this reason, the deterioration due to the impact of mercury ions and the consumption of mercury due to the mercury remaining in the phosphor particles are reduced. In addition, since the binder is made of yttrium oxide, mercury consumption in the binder portion is reduced. As a result, the luminance maintenance rate is superior to that of the conventional fluorescent lamp.
Japanese Patent Publication No. WO2002 / 047112 ("Disclosure of Invention" column) JP 2002-164018 A

  However, the phosphor layer of Patent Document 1 has a problem that it easily peels from the inner surface of the glass bulb. There is a possibility that the phosphor layer may be peeled off by an impact during the manufacturing process, product packaging, or transportation after shipment. The portion where the phosphor layer is peeled off and appears as a shadow at the time of lighting, causing uneven brightness. Fluorescent lamps with a possibility of peeling off the phosphor layer can be inspected and removed before shipment, but this leads to a decrease in yield.

In order to enhance the adhesion of the phosphor layer to the glass bulb, it is considered that the proportion of yttrium oxide in the phosphor layer may be increased. However, yttrium oxide has a property of absorbing a small amount of ultraviolet light having a wavelength of 254 nm for exciting the phosphor. Therefore, simply increasing the amount of yttrium oxide will decrease the luminance.
The same problem as described above may occur in an external electrode fluorescent lamp (EEFL) in which an external electrode is provided on the outer periphery of the glass bulb instead of the internal electrode.

  In view of the above problems, an object of the present invention is to provide a fluorescent lamp in which a phosphor layer is hardly peeled off while suppressing a decrease in luminance.

  In order to achieve the above object, a fluorescent lamp according to the present invention is a fluorescent lamp having a glass bulb and a phosphor layer formed on the inner surface side of the glass bulb, wherein the phosphor layer comprises a plurality of fluorescent lamps. Body particles and a binder that surrounds the phosphor particles and connects the phosphor particles, the binder comprising yttrium oxide and an alkaline earth metal borate as components. Features.

The alkaline earth metal borate is CBB.
Furthermore, in the phosphor layer, when the total weight ratio of yttrium oxide to the total weight 100 of the phosphor particles is A and the total weight ratio of the alkaline earth metal borate is B, A and B are 0.1 ≦ A ≦ 0.6 and 0.4 ≦ (A + B) ≦ 0.7.

  The plurality of phosphor particles include phosphor particles that emit red light, phosphor particles that emit green light, and phosphor particles that emit blue light. Each of the phosphor particles that emit red light includes europium-activated yttrium oxysal. Each of the phosphor particles formed of a phosphor material selected from phyto, europium activated phosphorus, vanadium, yttrium oxide, and manganese activated magnesium oxide, magnesium fluoride, germanium oxide, It is formed of a phosphor material selected from manganese co-activated barium / magnesium aluminate, manganese-activated cerium / magnesium / zinc aluminate, and terbium-activated cerium / magnesium aluminate.

According to the fluorescent lamp of the present invention, the binder that surrounds the phosphor particles and connects the phosphor particles is made of yttrium oxide that is strong against the impact of mercury ions, and the alkaline earth that has better binding power than this. Since the metal borate is used as a component, it is possible to prevent the phosphor layer from dropping from the inner surface of the glass bulb while suppressing a decrease in luminance due to a change with time.
Further, among the alkaline earth metal borates, by using CBB, the adsorption of mercury can be reduced, and as a result, the reduction in luminance can be further suppressed.

Furthermore, by setting the total weight of yttrium oxide and alkaline earth metal borate and the mixing ratio of the two in the above range, in addition to suppressing the falling off of the phosphor layer, it results from the coloring of the binder generated in the manufacturing process. The effect of suppressing the decrease in luminance is obtained.
Further, by selecting the above phosphor material for forming each phosphor particle, the fluorescent lamp can emit light in a wider chromaticity range.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1A is a longitudinal sectional view showing a schematic configuration of a cold cathode fluorescent lamp 10 according to an embodiment. In all the figures including this figure, the scales between the constituent members are not unified.
The cold cathode fluorescent lamp 10 has a glass bulb 16 in which both ends of a glass tube having a circular cross section are hermetically sealed with lead wires 12 and 14. The glass bulb 16 is made of hard borosilicate glass and has a total length of 720 mm, an outer diameter of 3 mm, and an inner diameter of 2 mm.

The glass bulb 16 is filled with about 2 mg of mercury (not shown) and a mixed gas (not shown) composed of plural kinds of rare gases such as argon (Ar) gas and neon (Ne) gas. .
The lead wires 12 and 14 are joints of internal lead wires 12A and 14A made of tungsten and external lead wires 12B and 14B made of nickel, respectively. Both ends of the glass tube are hermetically sealed at the internal lead wires 12A and 14A. The internal lead wires 12A and 14A and the external lead wires 12B and 14B both have a circular cross section. The inner lead wires 12A and 14A have a wire diameter of 1 mm and a total length of 3 mm, and the outer lead wires 12B and 14B have a wire diameter of 0.8 mm and a total length of 10 mm.

  Electrodes 18 and 20 are joined to the inner end portions of the internal lead wires 12A and 14A supported by the end portions of the glass bulb 16 by laser welding or the like, respectively. The electrodes 18 and 20 are so-called hollow electrodes having a bottomed cylindrical shape, and are formed by processing a niobium rod. The reason why the hollow electrodes are used as the electrodes 18 and 20 is that they are effective in suppressing sputtering in the electrodes caused by the discharge when the lamp is lit (for details, see JP-A-2002-289138). ).

The electrodes 18 and 20 have the same shape, and the dimensions of each part shown in FIG. 1B are as follows: electrode length L1 = 5 mm, outer diameter p1 = 1.70 mm, wall thickness t = 0.10 mm, (inner diameter p2 = 1.65 mm).
A phosphor layer 22 having a thickness of about 16 μm is formed on the inner surface of the glass bulb 16.
2A is an enlarged view of the phosphor layer 22, and FIG. 2B is a cross-sectional view of the phosphor layer 22 portion in the C portion shown in FIG. 2A.

The phosphor layer 22 includes a plurality of phosphor particles 24 and a binder 26.
Each of the phosphor particles 24 includes red-emitting europium-activated yttrium oxide [Y ₂ O ₃ : Eu ³⁺ ] (abbreviation: YOX), green-emitting cerium / terbium-activated lanthanum phosphate [LaPO ₄ : Ce ³⁺ , Tb]. ³⁺ ] (abbreviation: LAP) and blue-emitting europium activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ] (abbreviation: BAM). Has been.

The binder 26 contains alkaline earth metal borate (hereinafter referred to as “CBB”) and yttrium oxide as its components. Both the components constituting the binder 26 have a function of connecting the phosphor particles 24 to each other and fixing the phosphor particles 24 to the inner wall of the glass bulb 16.
In addition to this function, yttrium oxide has a function of protecting phosphor particles from the impact of mercury ionized by ionization when the lamp is turned on. In addition, yttrium oxide blocks ultraviolet rays having a wavelength of 185 nm (blocking at least 70%) out of ultraviolet rays having two wavelengths such as 185 nm and 254 nm emitted from mercury, and transmits ultraviolet rays having a wavelength of 254 nm (transmittance of about 85%). ). Ultraviolet light having a wavelength of 185 nm degrades the phosphor. Ultraviolet light having a wavelength of 254 nm exclusively excites the phosphor and is converted into visible light.

On the other hand, CBB is added exclusively to enhance the binding force of the binder 26. CBB is also transparent to ultraviolet rays having a wavelength of 254 nm.
In the phosphor layer 22 formed by the manufacturing method to be described later, among the plural (innumerable) phosphor particles 24, like the phosphor particles indicated by reference numeral 24A in FIG. Although some of the surfaces are covered, it is assumed that there are also phosphor particles in which a part of the surface is covered with a binder and the remaining surface is exposed, although not shown. . However, any phosphor particle is surrounded by the binder, whether totally (completely) or partially.

Next, of the manufacturing processes of the cold cathode lamp 10 having the above-described configuration, processes related to the formation of the phosphor layer 22 will be described with reference to FIG. The method of forming the phosphor layer 22 is basically the same as the method described in Patent Document 1 except that the configuration of the suspension described below is different. Therefore, the details will be omitted and only the main points will be described.
First, in step D shown in FIG. 3, a suspension containing phosphor particles is attached to the inner surface of the glass tube 30 that is a material of the glass bulb 16.

Specifically, a tank 34 containing the suspension 32 is prepared. The suspension 32 is made of butyl acetate as an organic solvent, a predetermined amount of phosphor particles, yttrium carboxylate [Y (C _n H _{2n + 1} COO) ₃ ] as an yttrium compound, CBB particles, a thickener. Nitrocellulose (NC) is added.
Then, the glass tube 30 is held vertically with the lower end immersed in the suspension 32. The inside of the glass tube 30 is exhausted from the upper end of the glass tube 30 by a suction force of a vacuum pump (not shown), and the suspension 32 is sucked up by making the inside of the glass tube 30 a negative pressure. While the liquid level in the glass tube 30 reaches the upper end (predetermined height), the suction is stopped and the glass tube 30 is pulled up from the suspension 32.
Thereby, the suspension 32 adheres in a film shape to a predetermined region on the inner periphery of the glass tube 30.

Dry hot air (25 to 30 ° C.) was blown into the glass tube 30 to dry the suspension 32 adhering to the film (this step is not shown), and then the suspension 32 was sucked in Step D A part of the dry film near the end portion that becomes the side is removed (step E).
Next, as shown in step F, the glass tube 30 is inserted into the quartz tube 36 and laid down, and heated with a burner 40 from the outside of the quartz tube 36 while air 38 is fed into the quartz tube 36, Bake (sinter) for 5 minutes. The heating temperature by the burner 40 is adjusted so that the inner peripheral surface of the glass tube 30 becomes 650 to 750 ° C.

By this firing, yttrium carboxylate is thermally decomposed to form glassy yttrium oxide (Y ₂ O ₃ ).
In the firing step, the CBB particles are melted to form a glassy film.
As described above, the phosphor layer 22 (FIGS. 1 and 2) is formed.

(Test 1)
In addition to the cold cathode fluorescent lamp 10 (Example) in which the phosphor layer is composed of phosphor particles, yttrium oxide, and CBB as described above, the inventor of the present application, for comparison purposes, Two types of cold cathode fluorescent lamps having different configurations were produced.
One is a cold cathode fluorescent lamp (Comparative Example 1) in which the phosphor layer is composed of phosphor particles and CBB, and the other is a cold cathode fluorescent lamp (in which the phosphor layer is composed of phosphor particles and yttrium oxide). Comparative Example 2).

The total weight ratio of yttrium oxide and / or CBB in each of the example, comparative example 1, and comparative example 2 when the weight of all phosphor particles was 100 was as follows.
Example: Yttrium oxide: 0.4, CBB: 0.2
Comparative Example 1 CBB: 1.0
Comparative Example 2 Yttrium oxide: 0.6
The above three types of lamps were turned on for a total of 2000 hours, and changes in luminance with time were examined.

The result is shown in FIG.
The luminance of the lamp immediately after the start of the test (hereinafter referred to as “initial luminance”) is the highest in Comparative Example 1, followed by Example and Comparative Example 2. The following reasons can be considered for this to happen. CBB transmits ultraviolet light having a wavelength of 254 nm, which contributes to phosphor emission, better than yttrium oxide. Further, the phosphor particles in the lamp of Comparative Example 1 are more exposed from the binder than the phosphor particles of the other two types of lamps. Therefore, since the phosphor particles in the lamp of Comparative Example 1 receive more ultraviolet rays than the other two types of fluorescent lamps, it seems that the initial luminance is the highest.

  In addition, there is a difference in the initial luminance (even in subsequent luminances) between the example and the comparative example 2. Regarding this reason, the following can be considered. As will be described later, the binding force of the binder (Comparative Example 2) composed only of yttrium oxide is weaker than the binding force of the binder (Example) composed of CBB added thereto. Therefore, in Comparative Example 2, even if the phosphor layer does not come off, the fixing rate of the phosphor particles to the phosphor layer is poor, and it is presumed that the phosphor particles are not removed from the phosphor layer. The This seems to cause a luminance difference between the two.

  In the comparative example 1, it turns out that the brightness | luminance has fallen rapidly from the test start. As described in the Background Art section, since the phosphor particles of Comparative Example 1 have many exposed parts, they are easily deteriorated by the impact of mercury ions, and mercury is easily adsorbed by the phosphor particles. CBB also tends to adsorb mercury. Therefore, it is considered that the sharp decrease in luminance is due to the rapid deterioration of phosphor deterioration and mercury consumption at an early stage.

Based on the graph shown in FIG. 4, FIG. 5 shows a graph showing a change over time in the luminance maintenance ratio when the initial luminance is 100%.
As can be seen from FIG. 5, the decrease rate of the luminance maintenance rate after about 100 hours from the start of the test is substantially the same between the example and the comparative example 2, as can be seen from the fact that both graphs are substantially parallel. is there. It can be seen that the reduction rate of the luminance maintenance rate of Comparative Example 1 is larger than that of Example and Comparative Example 2.

The results of Test 1 are summarized as follows.
The example is superior to the comparative example 1 in terms of the luminance maintenance rate. That is, the example has a longer life than Comparative Example 1.
The example has a performance equivalent to or slightly higher than that of the comparative example 2 in terms of the luminance maintenance rate.
(Test 2)
In addition, the inventor of the present application has conducted an impact test for examining whether or not the phosphor layer has dropped due to impact by changing the mixing ratio of yttrium oxide and CBB in the phosphor layer.

Specifically, the total weight ratio of yttrium oxide in the range of 0 to 0.6 and the total weight ratio of CBB in the range of 0 to 0.7 when the weight of all phosphor particles is 100, respectively. It was changed at intervals of 0.1. Then, a plurality of types of test lamps of different combinations with different weight ratios were manufactured for each type, and the impact test of the phosphor layer was performed on this.
The reason why the upper limit of the total weight ratio of yttrium oxide is set to 0.6 is as follows. That is, as described above, the luminance of the lamp decreases as the amount of yttrium oxide increases. It is necessary to suppress a decrease in lamp brightness to some extent as compared with a conventional lamp using only CBB as a binder. In this case, the upper limit of the total weight ratio of yttrium oxide, which can suppress the decrease in luminance to 3% or less, is 0.6. If the luminance is reduced within 3%, there is no problem in practical use.

A test apparatus 50 used for the impact test is shown in FIG.
The test apparatus 50 includes a lamp support base 52 and a test bar fixing base 54. The lamp support base 52 and the test bar fixing base 54 are respectively fixed to the base 56.
The lamp support base 52 has a long “V block” shape in a direction perpendicular to the paper surface. The test lamp TL is placed on the lamp support base 52 such that the glass bulb portion is along the V-shaped groove of the lamp support base 52.

  The test bar fixing base 54 fixes the test bar 58 at one end thereof. The said fixed part becomes a fixed fulcrum. The test bar 58 includes a coil spring 60 and a plastic bar 62. A length L2 from the fixed fulcrum of the coil spring 58 to the connecting portion with the plastic rod 62 is 30 mm. The plastic rod 62 has a cylindrical shape with a diameter of 8 mm, and the length L3 from the connection portion with the coil spring 60 to the center of the V-groove is 20 mm. The plastic rod 62 is made of Teflon (registered trademark).

The test procedure by the test apparatus 50 having the above-described configuration is as follows.
(I) The test lamp TL is placed on the lamp support base 52.
(Ii) The plastic rod 62 is lifted and the coil spring 58 is bent to a position where its axis is inclined at an angle α = 45 ° from the horizontal direction. At this time, the load applied to the glass bulb hitting portion of the plastic rod 62 in the direction perpendicular to the axis of the plastic rod 62 is 0.1 kgf.

(Iii) The plastic rod 62 is released, the coil spring 58 is restored, and an impact is applied to the test lamp TL with the plastic rod 62.
(Iv) In the test lamp TL, it is visually confirmed whether or not the phosphor layer is removed.
The above (i) to (iv) were repeated 20 times for one test lamp. As a result, any one of the 20 lamps in which the phosphor layer had fallen out was rejected, and in all 20 lamps in which no phosphor layer had dropped out was accepted.

The test results are shown in FIG.
In FIG. 7, “A” indicates the mixing ratio of yttrium oxide, and “B” indicates the mixing ratio of CBB.
In FIG. 7, the test lamp corresponding to the location containing the letters “NG1” failed in the impact test. Other test lamps (not implemented for A = 0 and B = 0) passed the impact test. As can be seen from this result, it was confirmed that when B = 0, that is, when the binder was composed only of yttrium oxide, the phosphor layer was detached within the range of the test. In addition, even when A = 0, that is, when the binder is composed of only CBB, the phosphor layer falls off when the amount of CBB added is small as in the test range.

From FIG. 7, from the viewpoint of preventing the phosphor layer from falling off, “0.1 ≦ A” or “0.1 ≦ B” and “0.4 ≦ (A + B)” may be satisfied. I understand.
From the above results, it can be seen that, from the viewpoint of preventing the phosphor layer from falling off, it is only necessary to mix yttrium oxide and CBB to form a binder and to increase the total amount of both. However, the present inventor has found that when the total amount of both exceeds a certain limit, the glass bulb turns to light brown when observed from the outside, and this causes a decrease in luminance. This is presumably due to the following causes. When the yttrium carboxylate is thermally decomposed in the firing (sintering) step in the series of manufacturing steps, a hydrocarbon represented by the general formula C _n H _{2n + 2} is generated in addition to yttrium oxide. On the other hand, the CBB melts and becomes glassy. At this time, it is considered that the CBB takes in the hydrocarbon and turns brown.

  In FIG. 7, the test lamp corresponding to the location containing the letters “NG2” turns light brown, and the brightness decreases as it becomes a problem. is there. The acceptance criterion is the same as that described above for the upper limit of the weight ratio of yttrium oxide to the total weight of the phosphor particles. That is, a lamp whose luminance was reduced by more than 3% compared to a conventional lamp using only CBB as a binder was determined as rejected (NG2).

From FIG. 7, it can be seen that “A ≦ 0.6” or “B ≦ 0.6” and “(A + B) ≦ 0.7” may be satisfied from the viewpoint of preventing a decrease in luminance.
As described above, from both the viewpoints of preventing the phosphor layer from falling off and preventing the luminance from decreasing, yttrium oxide and CBB are set to “0.1 ≦ A ≦ 0.6” (or “0.1 ≦ B ≦ 0.6”) and , “0.4 ≦ (A + B) ≦ 0.7” (in FIG. 7, a portion surrounded by a thick frame and containing the characters “OK”) is mixed to form a binder. It will be good.

As described above, the present invention has been described based on the embodiment. However, the present invention is not limited to the above-described form, and for example, the following form is also possible.
(1) In the above embodiment, a cold cathode fluorescent lamp (CCFL) has been described as an example. However, the present invention is not limited to this and can be applied to a so-called external electrode fluorescent lamp. The external electrode fluorescent lamp is, for example, a dielectric barrier discharge fluorescent lamp (EEFL: External Electrodes Fluorescent) in which, instead of the internal electrode, an external electrode is provided on the outer periphery of the glass bulb at both ends of the glass bulb and the glass tube wall is used as a capacitance. Lamp).
(2) As an alkaline earth metal borate, CBBP added with P (calcium pyrophosphate) may be used instead of CBB. In this case, it is preferable that the weight ratio is such that when CBB is 1, P is mixed at an arbitrary ratio of 0.7 or less. This is because if the ratio of P exceeds 0.7, mercury adsorption is likely to occur, and the luminance of the lamp is rapidly reduced. In other words, if CBB that does not contain P is used as the alkaline earth metal borate, it is possible to suppress a decrease in luminance due to mercury adsorption, compared to the case where CBBP is used.
(3) The phosphor material forming the phosphor particles is not limited to the above (YOX, LAP, BAM).

Along with the recent high color reproduction of liquid crystal display devices represented by liquid crystal TVs as part of high image quality, cold cathode fluorescent lamps and external electrode fluorescent lamps used as light sources for backlight units of the liquid crystal display devices There is a need to expand the reproducible chromaticity range.
Here, by using the phosphor material described below, it is possible to expand the chromaticity range, that is, to expand the NTSC triangle (NTSCtriangle) in the CIE1931 chromaticity diagram, compared to the case of using the phosphor material.

As a red phosphor material,
(i) Europium activated yttrium oxysulfite [Y ₂ O ₂ S: Eu ³⁺ ] (abbreviation: YOS), chromaticity coordinates: x = 0.651, y = 0.344
(ii) Europium-activated phosphorus, vanadium, yttrium oxide [Y (P, V) O ₄ : Eu ³⁺ ] (abbreviation: YPV), chromaticity coordinates: x = 0.658, y = 0.333
(iii) Manganese-activated magnesium oxide / magnesium fluoride / germanium oxide [3.5MgO / 0.5MgF ₂ / GeO ₂ : Mn ⁴⁺ ] (abbreviation: MFG), chromaticity coordinates: x = 0.711, y = 0 .287
You can choose from.

As a green phosphor material,
(i) Europium / manganese co-activated barium aluminate / magnesium [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ] (abbreviation: BAMMn), chromaticity coordinates: x = 0.139, y = 0.574
(ii) Manganese-activated cerium aluminate / magnesium / zinc [Ce (Mg, Zn) Al ₁₁ O ₁₉ : Mn ²⁺ ] (abbreviation: CMZ), chromaticity coordinates: x = 0.164, y = 0.722
(iii) Terbium-activated cerium magnesium aluminate [CeMgAl ₁₁ O ₁₉ : Tb ³⁺ ] (abbreviation: CAT), chromaticity coordinates: x = 0.267, y = 0.663
You can choose from.

Incidentally, the chromaticity coordinates of the phosphor material used in the above embodiment are as follows.
YOX (x = 0.644, y = 0.353), LAP (x = 0.351, y = 0.585), BAM (x = 0.148, y = 0,056)
The chromaticity range is expanded when both YOX and LAP are replaced with the phosphor materials (i) to (iii) described above, and when only one is replaced.
(4) Further, as the blue phosphor material, the following may be used instead of BAM.

(i) Europium-activated barium magnesium oxide adhering to lanthanum oxide [BaMg ₂ Al ₁₆ O ₂₇ : La ₂ O ₃ attached to Eu ²⁺ ] (abbreviation: LaBAM + La ₂ O ₃ coat), chromaticity coordinates: (x = 0 .148, y = 0.156) can also be used.
LaBAM is formed by attaching fine particles made of lanthanum oxide, which is a metal oxide, to particles made of europium-activated barium / magnesium aluminate, and exhibits a higher luminance maintenance rate than BAM.

(ii) Strontium, calcium, chloroapatite [(Sr, Ca, Ba) ₅ (PO ₄ ) ₃ Cl ₂ : Eu ²⁺ ] (abbreviation: SCA), chromaticity coordinates: x = 0.151, y = 0.065
The chromaticity coordinate values shown in the above (3) and (4) are representative values in each phosphor material, and the chromaticity coordinates indicated by each phosphor material due to the measurement method (measurement principle) and the like. The value may be slightly different from the value listed above.
(5) The phosphor material used for emitting each color of red, green, and blue is not limited to one type, and a plurality of types may be used in combination.

  The fluorescent lamp according to the present invention can be suitably used as a light source of a backlight unit in a liquid crystal display panel, for example, which has a small luminance unevenness due to the falling off of the phosphor layer and is particularly required to have a long life. is there.

(A) is a longitudinal cross-sectional view of the cold cathode fluorescent lamp which concerns on embodiment, (b) is a figure for demonstrating the dimension of the electrode which is one of the structural members of the said cold cathode fluorescent lamp. . (A) is an expansion schematic diagram of the fluorescent substance layer in the said cold cathode fluorescent lamp, (b) is sectional drawing of the C section in (a). It is a figure which shows a part of manufacturing process of the said cold cathode fluorescent lamp. It is a graph showing the time-dependent change of the brightness | luminance of each cold cathode fluorescent lamp in the comparative example 1, the comparative example 2, and an Example. It is a graph showing the time-dependent change of the brightness | luminance maintenance factor created based on the graph shown in the said FIG. 4, when an initial stage brightness | luminance is set to 100%. It is a figure which shows the test device which performs the dropping test of the fluorescent substance layer by impact. It is a figure which shows the result of the said drop-off test.

Explanation of symbols

10 Cold Cathode Fluorescent Lamp 16 Glass Bulb 22 Phosphor Layer 24 Phosphor Particle 26 Binder

Claims (4)

A fluorescent lamp having a glass bulb and a phosphor layer formed on the inner surface side of the glass bulb,
The phosphor layer is
A plurality of phosphor particles;
A binder that surrounds the phosphor particles and connects the phosphor particles, the binder comprising yttrium oxide and an alkaline earth metal borate as components; and
A fluorescent lamp comprising:   The fluorescent lamp according to claim 1, wherein the alkaline earth metal borate is CBB. In the phosphor layer,
When the total weight ratio of yttrium oxide to the total weight 100 of the phosphor particles is A and the total weight ratio of the alkaline earth metal borate is B, A and B are:
0.1 ≦ A ≦ 0.6
0.4 ≦ (A + B) ≦ 0.7
The fluorescent lamp according to claim 1 or 2, wherein the fluorescent lamp is in the range. The plurality of phosphor particles include phosphor particles that emit red light, phosphor particles that emit green light, and phosphor particles that emit blue light.
Each phosphor particle emitting red light is a phosphor material selected from europium activated yttrium oxysulfite, europium activated phosphorus, vanadium, yttrium oxide, and manganese activated magnesium oxide, magnesium fluoride, germanium oxide. Formed with
Each phosphor particle emitting green light is a phosphor selected from europium / manganese co-activated barium / magnesium aluminate, manganese-activated cerium / magnesium / zinc aluminate, and terbium-activated cerium / magnesium aluminate The fluorescent lamp according to any one of claims 1 to 3, wherein the fluorescent lamp is made of a material.

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