JP2005267974A - Glass composition for cold cathode fluorescent lamp, cold cathode fluorescent lamp and backlight unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass composition for cold cathode fluorescent lamp capable of restraining the irradiation amount of X-ray of 313 nm, capable of improving brightness based on excited light emission component. <P>SOLUTION: The glass composition for cold cathode fluorescent lamp is composed of silicon dioxide and boron oxide as fundamental component, and the glass composition contains titanium oxide by 0.01 wt.% or more and 3 wt.% or less, and europium oxide by 0.01 wt.% or more and 10 wt.% or less. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a glass composition for a cold cathode fluorescent lamp, a cold cathode fluorescent lamp using the glass composition, and a backlight unit equipped with the cold cathode fluorescent lamp.

In general, an acrylic resin diffusion plate is used in a backlight unit of a liquid crystal television. However, the diffusion plate made of acrylic resin is likely to be warped due to moisture absorption, and dimensional error becomes a problem when the size is increased. Therefore, a diffusion plate made of PC (polycarbonate) resin is used for the backlight unit of a large liquid crystal television. ing.
However, the diffusion plate made of PC resin has a defect that the brightness of the backlight unit is lowered due to significant deterioration and discoloration caused by ultraviolet rays of 313 nm emitted from the cold cathode fluorescent lamp. In view of this, the inventors of the present application created a cold cathode fluorescent lamp in which the amount of radiation of 313 nm ultraviolet rays was suppressed and filed an application earlier.

In the cold cathode fluorescent lamp, since the ultraviolet ray absorber is doped in the range of 1 to 3 wt% on the glass bulb, the radiation amount of 313 nm ultraviolet rays is suppressed. Therefore, even when used in the backlight unit, the PC resin diffusion plate is hardly deteriorated or discolored, and the luminance of the backlight unit is hardly lowered.
On the other hand, the backlight unit of a liquid crystal television is desired to have high luminance. In order to improve the luminance of the backlight unit, it is effective to improve the luminance of the cold cathode fluorescent lamp used in the backlight unit.

As one method for improving the brightness of the cold cathode fluorescent lamp, there is a method of providing a light emitting function to the glass bulb of the cold cathode fluorescent lamp. For example, Patent Document 1 discloses a fluorescent lamp in which a glass bulb is provided with a light emitting function by doping an excitation light emission component into the glass bulb. The excitation light-emitting component emits visible light when it receives ultraviolet rays, so that the luminance of the fluorescent lamp is improved. Further, the excitation light emitting component not only emits visible light when receiving ultraviolet light, but also emits ultraviolet light having a longer wavelength than the received ultraviolet light. The amount of visible light is increased and the brightness of the fluorescent lamp is improved.
JP 2002-83569 A

  However, the inventors have found that when the glass bulb is doped with both the excitation light-emitting component and the ultraviolet absorber, the amount of visible light and long-wavelength ultraviolet light emitted from the excitation light-emitting component is reduced. In particular, when the ultraviolet absorber was doped within a range of 1 to 3 wt% in order to suppress the radiation amount of 313 nm ultraviolet rays, the visible light and the long wavelength ultraviolet rays were hardly emitted from the excitation light emitting component.

  Therefore, in view of the above-mentioned problems, the present invention mainly aims to provide a glass composition for a cold cathode fluorescent lamp that can suppress the amount of radiation of 313 nm ultraviolet rays and can improve the luminance by an excited luminescence component. And Another object of the present invention is to provide a cold cathode fluorescent lamp having a glass bulb formed of the glass composition, and a backlight unit on which the cold cathode fluorescent lamp is mounted.

In order to solve the above-mentioned problems, a glass composition for a cold cathode fluorescent lamp according to the present invention comprises a silicon dioxide (SiO ₂ ) and a boron oxide (B ₂ O ₃ ) as basic constituent components. It is characterized by comprising 0.01 wt% or more and 3 wt% or less of titanium oxide (TiO ₂ ) and 0.01 wt% or more and 10 wt% or less of europium oxide (Eu ₂ O ₃ ) in its components. To do.

Further, in a specific aspect of the glass composition for a cold cathode fluorescent lamp according to the present invention, 55 wt% or more and 80 wt% or less of silicon dioxide, 10 wt% or more and 25 wt% or less of boron oxide, and 1 wt% or more and 10 or less of aluminum oxide. (Al ₂ O ₃ ), 3 wt% or more and 20 wt% or less of R ₂ O (R: at least one element selected from lithium (Li), sodium (Na) and potassium (K)), and 1 wt% 8 wt% or less of R′O (R ′: at least one element selected from magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and zinc (Zn)), 0 wt% % Or more and 5 wt% or less of zirconium oxide (ZrO) is contained in the component.

Furthermore, in another specific aspect of the glass composition for a cold cathode fluorescent lamp according to the present invention, the thermal expansion coefficient in the range of 30 ° C. or more and 380 ° C. or less is 34 × 10 ⁻⁷ or more and 58 × 10 ⁻⁷ or less. It is characterized by that.
The cold cathode fluorescent lamp according to the present invention includes a glass bulb formed from the glass composition for a cold cathode fluorescent lamp.

  Moreover, the backlight unit according to the present invention is characterized in that the cold cathode fluorescent lamp is mounted.

  The glass composition for a cold cathode fluorescent lamp according to the present invention contains 0.01 wt% or more and 3 wt% or less of titanium oxide and 0.01 wt% or more and 10 wt% or less of europium oxide in its components. When a cold cathode fluorescent lamp is manufactured using the glass composition, the radiation amount of 313 nm ultraviolet rays is suppressed by the ultraviolet absorbing function of titanium oxide, and the luminance of the cold cathode fluorescent lamp is improved by the emission characteristics of europium oxide. In addition, since the emission characteristics of europium oxide are improved by titanium oxide, the luminance of the cold cathode fluorescent lamp is improved as compared with the case where europium oxide is contained alone. Therefore, even when used in a backlight unit for a large-sized liquid crystal television, the diffuser made of PC resin does not deteriorate or discolor, and the brightness of the backlight unit does not decrease. Rather, the brightness of the cold cathode fluorescent lamp is improved. The brightness of the unit is also improved.

  In particular, in the case of high-definition televisions among large-sized liquid crystal televisions, the aperture ratio is smaller than that of ordinary televisions, so that the luminance of the backlight unit needs to be increased, and the glass composition of the present invention is useful. Furthermore, in recent years, there has been an increasing demand for extending the life of liquid crystal televisions such as liquid crystal televisions that require an operating time of 60,000 hours or more. Therefore, the glass composition of the present invention that does not deteriorate or discolor a PC resin diffusion plate is provided. Useful.

Further, the glass composition for a cold cathode fluorescent lamp of the present invention comprises 55 wt% or more and 80 wt% or less of silicon dioxide, 10 wt% or more and 25 wt% or less of boron oxide, 1 wt% or more and 10 or less of aluminum oxide, and 3 wt% or more. 20 wt% or less of R ₂ O (R: at least one element selected from lithium, sodium and potassium) and 1 wt% to 8 wt% of R′O (R ′: magnesium, calcium, strontium, barium and When the glass composition contains at least one element selected from zinc) and zirconium oxide in an amount of 0 wt% to 5 wt%, the glass composition is more suitable for a cold cathode fluorescent lamp. .

Furthermore, when the glass composition for a cold cathode fluorescent lamp of the present invention is a glass composition having a thermal expansion coefficient of 34 × 10 ⁻⁷ or more and 58 × 10 ⁻⁷ or less within a range of 30 ° C. or more and 380 ° C. or less, Since the expansion coefficient of the glass bulb of the cold cathode fluorescent lamp is approximately the same as the expansion coefficient of the electrode used in the cold cathode fluorescent lamp, it is easy to seal the electrode on the glass bulb.
Since the cold cathode fluorescent lamp according to the present invention includes a glass bulb formed from the glass composition for a cold cathode fluorescent lamp, the amount of radiation of ultraviolet rays at 313 nm is small and the brightness is high.

  Since the backlight unit according to the present invention includes the cold cathode fluorescent lamp, the backlight unit has high luminance and is unlikely to have a decrease in luminance.

(Description of glass composition)
The glass composition according to the embodiment of the present invention is a glass composition containing silicon dioxide and boron oxide as basic constituent components, and includes the following components.
Silicon dioxide: 67 wt%, boron oxide: 18.5 wt%, aluminum oxide: 3 wt%, sodium oxide _{(Na 2 O): 1wt%} , potassium oxide _{(K 2 O): 5wt%} , magnesium oxide (MgO): 0. 5 wt%, calcium oxide (CaO): 1wt%, zirconium oxide: 1 wt%, iron oxide _{(Fe 2 O 3): 0.02wt} %, titanium oxide: 0.5 wt%, europium oxide: 2.5 wt%.

In addition, that silicon dioxide and boron oxide are the basic constituents means that the content of silicon dioxide and boron oxide in the glass composition is high.
In the present embodiment, the glass composition is configured as described above, but the configuration of the glass composition is not limited to this. However, the glass composition preferably has components in the following ranges in order to maintain the characteristics as a glass bulb of a cold cathode fluorescent lamp.

Silicon dioxide: 55~80wt%, boron oxide: 10 to 25 wt%, aluminum _{oxide: 1~10wt%, R 2 O (} R: Li, at least one element selected from sodium and potassium): 3-20 wt %, R′O (R ′: at least one element selected from magnesium, calcium, strontium, barium and zinc): 1 to 8 wt%, zirconium oxide: 0 to 5 wt%, titanium oxide: 0.01 to 3 wt%, europium oxide: 0.01 to 10 wt%.

  Silicon dioxide is a main component that forms a network structure of glass. When silicon dioxide is less than 55 wt%, the chemical durability of the glass becomes insufficient, and the expansion coefficient of the glass becomes too large, resulting in poor sealing with the electrode portion. If the amount of silicon dioxide exceeds 80 wt%, it becomes difficult to melt the glass, and the expansion coefficient of the glass becomes too small to make it difficult to seal the electrode portion. Therefore, the silicon dioxide content is preferably 55 to 80 wt%.

Boron oxide is a component necessary for improving the meltability of the glass and adjusting the viscosity. If the boron oxide is less than 10 wt%, the viscosity of the glass becomes too high and melting becomes difficult, and if it exceeds 25 wt%, the chemical durability of the glass deteriorates. Therefore, the boron oxide content is preferably 10 to 25 wt%.
Aluminum oxide is a component that improves the chemical durability of glass. When the aluminum oxide content is less than 1 wt%, the chemical durability is deteriorated. When the aluminum oxide content is more than 10 wt%, it is difficult to melt the glass, and the viscosity at the time of processing the glass bulb becomes too high, causing striae in the glass bulb. Therefore, the content of aluminum oxide is preferably 1 to 10 wt%.

Specific examples of R ₂ O include lithium oxide (Li ₂ O), sodium oxide, and potassium oxide. R ₂ O to be contained in the glass composition may be at least one selected from lithium oxide, sodium oxide and potassium oxide. That is, any one kind may be sufficient and multiple kinds may be combined.

R ₂ O is a component necessary for improving the glass melting property and adjusting the viscosity and expansion coefficient. When the total of these components is less than 3 wt%, the viscosity becomes too high and melting becomes difficult. If the amount increases, not only will the expansion coefficient become too high, the electrode sealing performance will deteriorate, but also the chemical durability will deteriorate. Therefore, the content of R ₂ O is preferably 3 to 20 wt%.

  Specific examples of R′O include magnesium oxide, calcium oxide (CaO), strontium oxide (SrO), barium oxide (BaO), and zinc oxide (ZnO). R′O contained in the glass composition may be at least one selected from magnesium oxide, calcium oxide, strontium oxide, barium oxide, and zinc oxide. That is, any one kind may be sufficient and multiple kinds may be combined.

R′O is a component that improves the meltability and improves the devitrification tendency. When the content is less than 1 wt%, the meltability cannot be improved and the devitrification tendency cannot be improved, and when the content exceeds 8 wt%, the glass is crystallized. As a result, the glass bulb cannot be manufactured stably. Therefore, the content of R′O is preferably 1 to 8 wt%.
Zirconium oxide is a component that improves chemical durability. However, if it exceeds 5 wt%, the glass crystallizes and the glass bulb cannot be produced stably, so 0 to 5 wt% is preferable.

  Titanium oxide is an ultraviolet absorber and does not interfere with the emission properties of europium oxide like other ultraviolet absorbers, and conversely improves the emission properties of europium oxide by transferring energy to europium oxide. . When titanium oxide is less than 0.01 wt%, the ultraviolet absorption function and the function of improving the emission characteristics of europium oxide are not sufficiently exhibited, and when it exceeds 3 wt%, the glass is colored. Therefore, the content of titanium oxide is preferably 0.01 to 10 wt%.

Europium oxide is an excited luminescence component that emits light upon receiving ultraviolet light. When the amount of europium oxide is less than 0.01 wt%, the light emission characteristics are insufficient, and when the amount is more than 10 wt%, the glass is colored and the glass is phase-separated. Therefore, the content of europium oxide is preferably 0.01 to 10 wt%.
In addition, the combination of titanium oxide and europium oxide is the only combination obtained as a result of combining various ultraviolet absorbers and excitation luminescence components, and the emission characteristics of the excitation luminescence components even in the presence of the ultraviolet absorber. Is not inhibited, but rather the emission intensity of the excited luminescent component is improved.

In addition to the above compounds, cerium oxide (CeO ₂ ), iron oxide, vanadium oxide (V ₂ O ₅ ), tungsten oxide (WO ₃ ), tin oxide (SnO ₂ ), and the like as ultraviolet absorbing components in the glass composition. It is conceivable that it should be contained, but it must be made in an amount that does not impair the luminescent properties of europium oxide. Moreover, it is considered that antimony oxide (Sb ₂ O ₃ ), fluorine (F ₂ ), chlorine (Cl ₂ ), sulfur oxide (SO ₃ ) and the like are contained in the glass composition as a clarifying agent, but excessive inclusion Causes glass coloring.
(Description of cold cathode fluorescent lamp)
A cold cathode fluorescent lamp according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic view showing a main configuration of a cold cathode fluorescent lamp according to an embodiment of the present invention. The structure of the cold cathode fluorescent lamp 1 basically conforms to the structure of the cold cathode fluorescent lamp according to the prior art.
The glass bulb 2 of the cold cathode fluorescent lamp 1 is formed of the above glass composition, and has an outer diameter of about 4.0 mm, an inner diameter of about 3.4 mm, and an overall length of about 730 mm. The outer diameter, inner diameter, and overall length of the glass bulb 2 are not limited to the above. However, since the glass bulb 2 for the cold cathode fluorescent lamp 1 is desired to be a small diameter and thin tube, the outer diameter is 1. It is preferable that it is 8 (inner diameter is 1.4)-6.0 (inner diameter is 5.0) mm.

  The glass bulb 2 is hermetically sealed with bead glass 3 at both ends. Further, in the vicinity of both ends of the glass bulb 2, lead wires 4 made of tungsten and nickel having a diameter of about 0.8 mm pass through the bead glass 3 and are hermetically sealed at the tungsten wire portions of the lead wires 4. It has been stopped. Furthermore, a cup-shaped electrode 5 made of nickel or niobium is attached to the end of the lead wire 4 on the side disposed in the tube of the glass bulb 2. In addition, the bead glass 3, the lead wire 4, and the electrode 5 are not limited to the thing of said structure.

On the inner surface of the tube of the glass bulb 2, red, green and blue phosphors (Y ₂ O ₃ : Eu, LaPO ₄ : Ce, Tb, BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn) are mixed. The rare earth phosphor 6 is applied. The tube of the glass bulb 2 is filled with 0.8 to 2.5 mg of mercury and a neon / argon mixed gas (Ne + 5% Ar) having a cooling pressure of about 10 kPa.

As described above, the cold cathode fluorescent lamp according to the present invention has been specifically described based on the embodiment. However, the content of the present invention is not limited to the above embodiment.
(Description of backlight unit)
FIG. 2 is a schematic diagram showing a main configuration of a direct-type backlight unit according to an embodiment of the present invention. The structure of the direct-type backlight unit 10 according to the embodiment of the present invention basically conforms to the structure of the backlight unit according to the prior art.

  The envelope 11 is made of white PET (polyethylene terephthalate) resin, and includes a substantially rectangular reflecting plate 12 and a plurality of side plates 13 arranged so as to surround the reflecting plate 12. A plurality of cold cathode fluorescent lamps 1 arranged in parallel at equal intervals are stored in the envelope 11. Further, in the envelope 11, a diffusion plate 14 made of PC resin is disposed so as to face the reflection plate 12 with the cold cathode fluorescent lamp 1 interposed therebetween. In the backlight unit 10, the diffusion plate 14 side with respect to the cold cathode fluorescent lamp 1 is the light emission side of the backlight unit 10, and the reflector 12 side with respect to the cold cathode fluorescent lamp 1 is the backlight unit 10. On the light reflection side. Further, a diffusion sheet 15 formed of PC resin and a lens sheet 16 formed of acrylic resin are disposed on the light emission side of the diffusion plate 14 so as to overlap each other.

In the liquid crystal television provided with the backlight unit 10 as described above, the LCD panel 17 of the liquid crystal television is installed on the light emission side of the lens sheet 16.
As a typical shape of the backlight unit 10, in the case of the backlight unit 10 used for a liquid crystal television having a screen size of 32 inches, the envelope 11 has a width dimension of about 728 mm, a vertical width dimension of about 408 mm, and a depth dimension. Is set to about 19 mm. In the envelope 11, 16 cold cathode fluorescent lamps 1 are arranged with an interval of about 25.7 mm.

Although the backlight unit according to the present invention has been specifically described above based on the embodiment, the content of the present invention is not limited to the above-described embodiment.
(Explanation of experiment)
(1) Examination about the combination of an ultraviolet absorber and an excitation luminescent component Among the various ultraviolet absorbers and an excitation luminescence component, the combination which does not inhibit the luminescent property of an excitation luminescence component was examined.

As the ultraviolet absorber, titanium oxide, cerium oxide (CeO ₂ ), zinc oxide (ZnO) or the like having a function of shielding ultraviolet rays of 313 nm when doped into a glass bulb was used.
Further, as the excitation light-emitting component, titanium (Ti), zirconium (Zr), vanadium (V), niobium (Nb), tantalum (Ta), molybdenum (Mo), tungsten (W), thallium (Tl), tin ( Sn), lead (Pb), bismuth (Bi), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium ( Oxides of elements such as Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu) were used.

3 and 4 are graphs showing the influence of the ultraviolet absorber on the emission intensity of the excited luminescent component.
FIG. 3 shows the results for a combination of titanium oxide as an ultraviolet absorber and europium oxide as an excited luminescent component. In FIG. 3, graph A shows the emission intensity of the glass containing titanium oxide and europium oxide, and graph B shows the emission intensity of the glass containing europium oxide but not containing titanium oxide. The specific composition of the glass of graph A is shown in Table 1 at (e). The glass of graph B contains the same amount of silicon dioxide instead of titanium oxide.

  FIG. 4 shows the results of studies on a combination of titanium oxide as an ultraviolet absorber and terbium oxide as an excitation light-emitting component. In FIG. 4, graph C shows the emission intensity of the glass containing titanium oxide and terbium oxide, and graph D shows the emission intensity of the glass containing terbium oxide but not titanium oxide. The glasses of graphs C and D contain the same amount of terbium oxide instead of europium oxide in the glasses of graphs A and B.

励起発光成分の発光強度の測定には、分光蛍光光度計（日本分光 ＪＡＳＣＯ ＦＰ−６５００）を用いた。まず、測定用のガラス試料として、上記組成となるようにガラス原料を調合し、白金ルツボにて１５５０℃で６時間溶融し、厚さ３．５ｍｍの板状に成形加工した後、表面に研磨仕上げを施してガラス板を作製した。次に、水銀の主発光波長である２５４ｎｍの紫外線を各ガラス板に同じ面積ずつ照射し、当該ガラス板から発せられる蛍光発光をスリットにより各波長毎に分光して、発光スペクトルを検出した。

A spectrofluorophotometer (JASCO JASCO FP-6500) was used to measure the emission intensity of the excited luminescent component. First, as a glass sample for measurement, a glass raw material was prepared so as to have the above composition, melted at 1550 ° C. for 6 hours with a platinum crucible, molded into a plate shape with a thickness of 3.5 mm, and then polished on the surface Finished to produce a glass plate. Next, 254 nm ultraviolet light, which is the main emission wavelength of mercury, was irradiated to each glass plate in the same area, and the fluorescence emitted from the glass plate was split for each wavelength through a slit to detect an emission spectrum.

The main emission wavelength of europium oxide is 613 nm, and the main emission wavelengths of terbium oxide are 490 nm and 550 nm.
As is clear from FIG. 3, the emission intensity of europium oxide was increased by containing titanium oxide. On the other hand, as is clear from FIG. 4, the emission intensity of terbium oxide was reduced by containing titanium oxide. The same experiment as described above was performed for other combinations of the ultraviolet absorber and the excitation luminescence component, but the emission intensity of the excitation luminescence component decreased.

(2) Examination of content of titanium oxide The effect of the content of titanium oxide on the physical properties of glass was evaluated by making the content of europium oxide constant and making the content of titanium oxide different.
The glass of (a) in Table 1 does not contain titanium oxide or europium oxide. The glasses (b) to (h) all contain 5 wt% europium oxide, the titanium oxide content (b) is 0.005 wt%, and (c) is 0.01 wt%. (D) is 0.1 wt%, (e) is 0.5 wt%, (f) is 2 wt%, (g) is 3 wt%, and (h) is 3.1 wt% %.

  Glass samples for evaluation were prepared by preparing glass raw materials so as to have the compositions of (a) to (h), melted in a platinum crucible at 1550 ° C. for 6 hours, and molded into a shape necessary for physical property evaluation. . And about each glass sample, the thermal expansion coefficient, the light emission intensity of 613 nm, the transmittance | permeability of 313 nm, the transmittance | permeability of 400 nm, and the coloring degree of glass were measured or determined with the following method.

The thermal expansion coefficient is 30 to 380 ° C. by processing the glass into a rod shape having a diameter of 5 mm and a height of 10 mm, and using a thermomechanical analyzer (TAS300 TMA8140C, manufactured by Rigaku Corporation) by a compression load method (JIS R 3102). Measured over temperature range.
The emission intensity at 613 nm is calculated by calculating the relative value when the emission peak derived from europium oxide is measured by the above method and the emission intensity of the glass sample according to (a) is set to 100 based on the obtained result. It was digitized by.

The transmittance of 313 nm ultraviolet light was measured using a self-recording spectrophotometer (Hitachi U-4000 Spectrophotometer) by preparing a glass plate having a thickness of 3.5 mm as a glass sample. In addition, it has shown that the effect which glass shields an ultraviolet-ray is so large that the value of the transmittance | permeability of a 313 nm ultraviolet-ray is small.
The transmittance of ultraviolet light at 400 nm was measured by the same method as the transmittance of ultraviolet light at 313 nm. In addition, it shows that the transparency of glass is so high that the value of the transmittance | permeability of a 400 nm ultraviolet-ray is large.

The glass coloring determination was performed by visually observing the degree of coloration and transparency of the glass, and determining whether or not it could be used for a glass bulb of a cold cathode fluorescent lamp. Those that were determined to be usable were indicated with “◯”, and those that were determined not to be usable were indicated with “x”.
As shown in Table 1, first, emission of 613 nm was observed in each glass except glass (a) which did not contain europium oxide.

  When the content of titanium oxide is 0.005 wt%, the transmittance of ultraviolet light at 313 nm is 41%. However, the inventor has found that the transmittance of ultraviolet rays at 313 nm must be 20% or less in order to exert a shielding effect when used in a glass bulb of a cold cathode fluorescent lamp, and 41% is sufficient. Furthermore, it cannot be said that 313 nm ultraviolet rays are shielded. On the other hand, when the content of titanium oxide is 0.01 wt% or more, the transmittance of 313 nm ultraviolet light is 14% or less, so it can be said that the 313 nm ultraviolet light is sufficiently shielded. Rated as available.

  When the content of titanium oxide is 3.1 wt%, the transmittance at 400 nm is as low as 49%, and it can be said that the transparency of the glass is low. Moreover, the result of glass coloring determination was also “x”. On the other hand, when the content of titanium oxide is 3 wt% or less, the transmittance at 400 nm is 68% or more, so it can be said that the transparency of the glass is high. Moreover, the result of glass coloring determination was also “◯”, and the transparency by visual observation was maintained.

From the above results, it is preferable that the titanium oxide contained in the glass composition is 0.01 to 3 wt%.
(3) Examination about the compounding quantity of europium oxide By making content of titanium oxide constant and making content of europium different, the influence which content of europium oxide has on each physical property of a glass composition was evaluated.

  In the glass of (i) to (o) in Table 2, the content of titanium oxide is all 0.5 wt%, the content of europium oxide is (i) is 0.005 wt%, (j) Is 0.01 wt%, (k) is 0.5 wt%, (l) is 2.5 wt%, (m) is 7.5 wt%, (n) is 10 wt%, (O) is 10.1 wt%.

上記と同様の方法で各ガラス試料を形成し、上記と同様の方法で、熱膨張係数、６１３ｎｍの発光強度、３１３ｎｍの透過率、４００ｎｍの透過率、ガラスの着色度合いについて評価した。
酸化ユウロピウムの含有量が０．００５wt％の場合、６１３ｎｍの発光強度の相対値は０％であり全く発光が得られなかった。一方、酸化ユウロピウムの含有量が０．０１wt％以上の場合、６１３ｎｍの発光強度の相対値は、６７％以上となるため、発光特性の向上が期待できる。

Each glass sample was formed by the same method as described above, and the thermal expansion coefficient, the emission intensity of 613 nm, the transmittance of 313 nm, the transmittance of 400 nm, and the degree of coloring of the glass were evaluated by the same method as described above.
When the content of europium oxide was 0.005 wt%, the relative value of the emission intensity at 613 nm was 0%, and no emission was obtained. On the other hand, when the content of europium oxide is 0.01 wt% or more, the relative value of the emission intensity at 613 nm is 67% or more, so that the emission characteristics can be improved.

  When the content of europium oxide is 10.1 wt%, the transmittance at 400 nm is as low as 29%, and it can be said that the transparency of the glass is low. Moreover, the result of glass coloring determination was also “x”. On the other hand, when the content of europium oxide is 10 wt% or less, the transmittance at 400 nm is 59% or more, so it can be said that the transparency of the glass is high. Moreover, the result of glass coloring determination was also “◯”, and visual transparency was maintained.

  From the above results, it is preferable that the europium oxide contained in the glass composition is 0.01 to 10 wt%.

  The cold cathode fluorescent lamp and the backlight unit of the present invention can be used for liquid crystal televisions and other liquid crystal display devices. Particularly, it is suitable for a large-sized liquid crystal television, a large-sized liquid crystal display, and a high-definition liquid crystal television having a direct backlight unit equipped with a diffusion plate made of PC resin.

It is the schematic which shows the principal part structure of the cold cathode fluorescent lamp concerning one Embodiment of this invention. It is the schematic which shows the principal part structure of the direct-type backlight unit concerning one Embodiment of this invention. It is the graph shown about the influence which the ultraviolet absorber exerts on the emitted light intensity of an excitation light emission component. It is the graph shown about the influence which the ultraviolet absorber exerts on the emitted light intensity of an excitation light emission component.

Explanation of symbols

1 Cold cathode fluorescent lamp 2 Glass bulb 10 Backlight unit

Claims (5)

A glass composition for a cold cathode fluorescent lamp comprising silicon dioxide and boron oxide as basic components,
A glass composition for a cold cathode fluorescent lamp, comprising 0.01 wt% or more and 3 wt% or less of titanium oxide and 0.01 wt% or more and 10 wt% or less of europium oxide. 55 wt% to 80 wt% silicon dioxide, 10 wt% to 25 wt% boron oxide, 1 wt% to 10 wt aluminum oxide, and 3 wt% to 20 wt% R ₂ O (R: lithium, sodium and potassium 1 wt% or more and 8 wt% or less of R′O (R ′: at least one element selected from magnesium, calcium, strontium, barium and zinc) and 0 wt% The glass composition for a cold cathode fluorescent lamp according to claim 1, wherein the component contains zirconium oxide in an amount of 5% to 5% by weight. 3. The glass composition for a cold cathode fluorescent lamp according to claim 1, wherein a coefficient of thermal expansion within a range of 30 ° C. to 380 ° C. is 34 × 10 ⁻⁷ or more and 58 × 10 ⁻⁷ or less.   A cold-cathode fluorescent lamp comprising a glass bulb formed from the glass composition for a cold-cathode fluorescent lamp according to any one of claims 1 to 3.   5. A backlight unit, wherein the cold cathode fluorescent lamp according to claim 4 is mounted as a cold cathode fluorescent lamp.

Images