KR100788949B1 - Glass Tubing for Fluorescent Lamp - Google Patents

Abstract

The present invention provides a glass tube for a fluorescent lamp (CCFL) having a good UV resistance and excellent UV-ultraviolet ray matching property with matching Kovar, which is an introduction metal for electrodes, and a linear expansion coefficient.

Glass tube of fluorescent lamp contains CeO2 for UV protection effect, Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , NiO, CoO, Mo to prevent solarization ₃ O _4, ZnO, PbO, and at least one or more kinds of compositions containing selected from CdO, the coefficient of linear expansion in the 30 ~ 380 ℃ 43 ~ 55 × 10 -7 / ℃ a borosilicate glass outer diameter consisting of a 5.2 mm or less, Use of tubular glass with a thickness of 0.6 mm or less.

Cold Cathode Fluorescent Lamp, Glass Tube, COVA Electrode, Ultraviolet-Solarization

Description

Glass Tubing for Fluorescent Lamp

1 is a schematic diagram showing a Cold Cathode Fluorescent Lamp (CCFL).

2 is a schematic diagram showing a structure in which a cold cathode fluorescent lamp is used as a backlight in a TFT liquid crystal display device.

Explanation of symbols on the main parts of the drawings

1: Glass tube for fluorescent lamp (1a: Bulb, 1b: Bead)

2: phosphor

3: Kovar electrode

4: cold cathode fluorescent lamp (CCFL)

5: acrylic reflector

6: backlight module

7: TFT-liquid crystal display element

The present invention relates to a glass tube for a fluorescent lamp, more specifically CeO ₂ as a sunscreen, Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , At least one selected from NiO, CoO, Mo ₃ O ₄ , ZnO, PbO, and CdO is included, and it is composed of borosilicate glass having a linear expansion coefficient of 43 to 55x10 ^-7 / ° C at 30 to 380 ° C. Provided is a glass tube for a fluorescent lamp.

The light emitting principle of the fluorescent lamp for backlight is similar to that of general lighting fluorescent lamps, and the mercury gas encapsulated by the discharge between the electrodes is excited and applied to the inner wall surface of the envelope glass tube made of tubular glass by the ultraviolet rays emitted from the excited gas. The phosphor emits visible light. However, a big difference from the general fluorescent lamp is that the outer diameter of the glass tube is small and the thickness is thin.

In addition to the thinner, lighter, and lower power consumption of liquid crystal display devices, thinner and thinner are required for cold cathode fluorescent lamps for backlights.However, the thinner fluorescent lamps have structurally lowered mechanical strength and increased lamp heat generation. Since the envelope glass tube requires high-strength characteristics, Coba (Westinghouse Ele. Corp.), which is an introduction metal for electrodes, is a Fe-Ni-Co-based alloy, and the present application includes equivalent products of other companies. The coefficient of linear expansion with

Moreover, in order to improve luminous efficiency, the high frequency of a lighting circuit is advanced, and with this, the low dielectric loss is calculated | required by the tubular glass which is an insulator.

Conventionally, in the envelope of this cold cathode fluorescent lamp, Kovar sealing glass, which is a borosilicate hard glass having excellent mechanical strength, has been developed, and a fluorescent lamp using cobalt as an introduction metal has been commercialized.

However, since the fluorescent lamp envelope is formed and processed into a tubular shape simply by using the COVA sealing borosilicate glass which is generally used for various kinds of electron tubes, it is emitted from the excited mercury gas when it is turned on for a long time. The problem of glass discoloration (so-called ultraviolet solarization) is caused by ultraviolet rays.

When the glass is discolored, a decrease in luminance or a shift in the emission color occurs, resulting in deterioration of the quality of the liquid crystal display device. In addition, the UV blocking ability of the glass is low, the ultraviolet light emitted from the cold cathode fluorescent lamp discolors the acrylic reflector to reduce the reflection efficiency, causing a problem of lowering the brightness of the backlight.

As a countermeasure, in some cases, a method of coating Al ₂ O ₃ or TiO ₂ , which is a component that reflects or absorbs ultraviolet rays on the inner surface of the glass tube, and applies a phosphor thereon to form a multi-layer film, thus weakening the intensity of ultraviolet rays reaching the glass. Although it is implemented, it is difficult to form a homogeneous multilayer film | membrane with respect to a thin thickness tubular glass not only with the increase of a production cost in this method.

On the other hand, Japanese Patent Application Laid-Open No. 9-106784 includes at least one of TiO ₂ , PbO, and Sb ₂ O _{3 in} the composition of a thin fluorescent lamp envelope, but there is an attempt to improve ultraviolet solarization resistance, but the UV blocking effect is Inadequately, there is a problem that the acrylic reflector discolors to cause a decrease in the brightness of the lamp, and the glass itself becomes brown, which causes a decrease in transmittance in the visible region.

From such circumstances, there is a strong demand for the development of glass tubes for fluorescent lamps having UV resistance and excellent UV blocking effect.

In order to solve the above problems, an object of the present invention is to provide a fluorescent tube glass tube excellent in UV resistance (discoloration resistance) and excellent in harmful UV blocking effect.

The present invention, in order to achieve the above object, CeO ₂ as a sunscreen and Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , NiO, for preventing solarization For fluorescent lamps comprising at least one composition selected from CoO, Mo ₃ O ₄ , ZnO, PbO, CdO and consisting of borosilicate glass with a linear expansion coefficient of 43 to 55x10 ^-7 / ° C at 30 to 380 ° C. Provide a glass tube.

Here, the said glass tube is 5.2 mm or less in outer diameter, 0.6 mm or less in thickness, and it is preferable that it is a tubular shape.

In addition, the borosilicate glass is SiO ₂ 56 ~ 74%, B ₂ O ₃ 11-25%, Al ₂ O ₃ 1-10%, Li ₂ O + Na ₂ O + K ₂ O 4-16% by weight , ZrO ₂ 0.1-5%, CeO ₂ 0.1-1%, Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , NiO, CoO, Mo ₃ O ₄ , ZnO, It is preferable that at least 1 sort (s) chosen from PbO and CdO contain 0.1-3% of composition, respectively.

Here, the glass tube for the fluorescent lamp is preferably used as one component of the cold cathode fluorescent lamp which is a light source for the illumination device of the liquid crystal display element.

Hereinafter, the present invention will be described in detail based on the preferred embodiments.

1 shows the structure of a cold cathode fluorescent lamp (CCFL). The cold cathode fluorescent lamp is mainly used as a backlight of a transmissive liquid crystal display device represented by a TFT liquid crystal display device as shown in FIG.

The structure of the above-mentioned fluorescent lamp and the backlight structure of the transmissive liquid crystal display device are known structures, and the glass tube for the fluorescent lamp manufactured by the present invention is a key component.

In the glass tube for fluorescent lamp of the present invention, the glass composition is composed of borosilicate glass, which has borosilicate glass having high mechanical strength, low thermal expansion, excellent heat resistance, low dielectric loss, and fine stiffening (which can reduce the diameter of the tube). This is because it has the advantage of being easy to thin (thinner tube thickness).

When borosilicate glass contains CeO ₂ in the glass, it has excellent ultraviolet absorption effect. Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , NiO, CoO, Mo ₃ O ₄ , When at least one composition selected from ZnO, PbO, and CdO is contained, it exhibits ultraviolet solarization resistance (resistance to discoloration) and is difficult to color even after prolonged exposure to ultraviolet light generated inside a cold cathode fluorescent lamp. It has excellent blocking effect of harmful ultraviolet rays but does not discolor the glass itself and has high transmittance in the visible area, which does not cause the problem of decrease in luminance of fluorescent lamps.

Further, the reason for limiting the linear expansion coefficient of the borosilicate glass to 43 to 55 × 10 ⁻⁷ / ° C. (30 to 380 ° C.) is that if the linear expansion coefficient deviates from this range, the induction metal coba and the thermal expansion coefficient do not match, but the This is because cracks occur and the function as a cold cathode fluorescent lamp is impaired.

The glass tube for fluorescent lamps made of borosilicate glass has a size of 5.2 mm or less in outer diameter, preferably 3.5 mm or less in thickness, 0.6 mm or less in thickness, and preferably 0.5 mm or less in thickness. Due to the weight reduction, the cold cathode fluorescent lamps for lighting devices such as backlights cannot be made thinner.

Glass tube for fluorescent lamps is borosilicate glass, with weight percentages of SiO ₂ 56 ~ 74%, B ₂ O ₃ 11-25%, Al ₂ O ₃ 1-10%, Li ₂ O + Na ₂ O + K ₂ O 4 ~ 16 %, ZrO ₂ 0.1-5%, CeO ₂ 0.1-1%, Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , NiO, CoO, Mo ₃ O ₄ , ZnO, PbO, CdO It is very suitable to have a composition of 0.1 to 3%.

The reason which limited content of each component as mentioned above is as follows.

SiO ₂ is a main component necessary for constituting the skeleton of the glass, the content of which is 56 to 74%, and preferably 61 to 71%. If the SiO _{2 content} is more than 74%, the coefficient of thermal expansion is too low and the solubility is easily deteriorated, and if it is less than 56%, the chemical durability is easily deteriorated. If soot or the like is generated, it causes a decrease in luminance of the cold cathode fluorescent lamp.

B ₂ O ₃ is a component necessary for the adjustment of the improvement of solubility and viscosity, the content is 11 ~ 25%, preferably 16 ~ 23%. If the B ₂ O ₃ is less than 11% become difficult to dissolve it is also the viscosity as Kovar rod wear is too high. On the other hand, if it is more than 25%, the viscosity decreases excessively, a homogeneous glass cannot be obtained by evaporation, or the chemical durability deteriorates.

Al ₂ O ₃ has a remarkable effect in improving the stability of the glass, the content of which is 1 to 10%, and preferably 1 to 5%. Al ₂ O ₃ and that is more than 10% dissolution of the glass is difficult, is less than 1% are easily to glass devitrification, it is difficult to manufacture and stable formation of a homogeneous glass.

Li ₂ O, Na ₂ O and K ₂ O, which are alkali metal oxides, are components added to facilitate the dissolution of the glass and to adjust the coefficient of linear expansion and viscosity, and the content thereof is 4 to 16% in total. 5 to 13%. If the total amount of these components is 16% or more, the coefficient of linear expansion is too high, and the viscosity is too low, which is not suitable for sealing the bar, and also causes a significant decrease in chemical durability, and if the total amount is less than 4%, the coefficient of expansion is too reversed. Becomes smaller.

The content of each component is 0.1 to 4% Li ₂ O (preferably 0.1 to 3%), Na ₂ O 0.1 to 4.3% (preferably 0.1 to 3.9%), K ₂ O 0.1 to 15% (preferably 0.1 to 4%). 13%) is very suitable. When Li ₂ O is more than 4%, the devitrification property tends to deteriorate, and the coefficient of thermal expansion is too high. When Na ₂ O is more than 4.3%, Na ions contaminate the phosphor in the thermal process in the manufacture of fluorescent lamps, causing a decrease in luminance. The coefficient of thermal expansion may be too high.

If K ₂ O exceeds 15%, the coefficient of thermal expansion becomes too high.

ZrO ₂ is a component that improves chemical durability and prevents alkali swelling and soot, and its content is 0.1 to 5%, preferably 0.1 to 3%. If ZrO ₂ is more than 5%, the devitrification property deteriorates and the glass becomes nonuniform, and the dimensional accuracy deteriorates or appearance defects occur, making it difficult to obtain high quality glass.

Both CeO ₂ is a component which gives high ultraviolet-ray solarization property of glass and raises the ultraviolet-absorption ability, The total amount is 0.1 to 1%, Preferably it is 0.2 to 0.6%. When the total amount of these components exceeds 1%, the glass is colored brown or blackish brown, which is directly connected to the decrease in brightness, and the ultraviolet absorption end is close to the visible light region, which is undesirable because it causes a decrease in transmittance in the low wavelength visible region. not.

Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , NiO, CoO, Mo ₃ O ₄ , ZnO, PbO, CdO prevent oxidation of Ce ions The borosilicate glass is added as a component capable of preventing the coloration by SrO, BaO, MgO, ZnO, P ₂ O ₅ , As _{2 for the} purpose of adjusting the viscosity of the glass and improving weather resistance, solubility, and clarity. It is possible to appropriately add components such as O ₃ , Sb ₂ O ₃ , SO ₃ , F ₂ , and Cl ₂ .

Moreover, the glass tube for cold cathode fluorescent lamps of this invention is manufactured as follows.

First, the glass raw materials are combined so as to have a desired composition. For example, by weight percent SiO ₂ 56-74%, B ₂ O ₃ 11-25%, Al ₂ O ₃ 1-10%, Li ₂ O + Na ₂ O + K ₂ O 4-16%, ZrO ₂ 0.1-5%, CeO ₂ 0.1-1%, Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , NiO, CoO, Mo ₃ O ₄ , ZnO, PbO, CdO It is combined so that the content of at least one component selected from among 0.1 to 3% of the composition. Subsequently, the combined glass raw material is poured into a glass melting furnace, melted and vitrified at 1500-1650 ° C., and then formed into a tubular shape using a single-pass method, a downdraw method, and cut into a predetermined length. At this time, you may shape | mold so that it may have a desired outer diameter and thickness directly, and after making a mother cap with a large outer diameter and thickness, you may make it tubular by the reed method. Thus, the glass tube for fluorescent lamps of this invention which consists of tubular glass from 43-55x10 <^-7> / degreeC of linear expansion coefficient, and borosilicate glass of outer diameter 5.2mm or less and thickness 0.6mm or less is obtained.

Hereinafter, the coefficient of linear expansion, the ultraviolet radiation resistance and the ultraviolet absorption stage of the glass tube for fluorescent lamps of the present invention are evaluated.

Tables 1-3 show the Example (sample No. 1-12) and the comparative example (sample No. 13-15) of the borosilicate glass which comprises the glass tube of this invention.

TABLE 1

Sample No. One 2 3 4 5 Glass composition (wt%) SiO2 B2O3 Al2O3 Li2O Na2O K2O ZrO2 CeO2 V2O5 67.7 18.5 3.8 0.9 0.9 7.6 0.3 0.3- 70.5 16.1 3.4 0.8 0.6 8.0 0.1 0.5- 65.3 17.9 5.8 0.7 1.2 8.0 0.5 0.3 0.3 68.7 18.7 3.5 0.5 0.4 7.7 0.2-0.3 67.5 18.5 4.0 0.8 1.5 7.3 0.1 0.3- Linear expansion coefficient [30 ~ 380 ℃] (X10-7 / ℃) 52.2 50.5 54.2 47.8 53.1 Transmittance reduction amount (%) after ultraviolet irradiation 0.3 0.4 0.3 0.8 0.5 UV absorption stage (nm) 290 310 330 300 290

TABLE 2

Sample No. 6 7 8 9 10 Glass composition (wt%) SiO2 B2O3 Al2O3 Li2O Na2O K2O ZrO2 CeO2 V2O5 71.2 16.2 4.3 1.2 0.5 5.8 0.3 0.5- 64.8 21.2 6.2 0.6 3.2 3.6 0.2-0.2 66.7 18.8 3.5 0.8 0.9 8.2 0.5 0.4 0.2 64.8 18.2 8.7 0.5 2.3 4.1 0.9-0.5 66.8 17.7 4.9 2.7 0.2 6.0 1.0 0.7- Linear expansion coefficient [30 ~ 380 ℃] (X10-7 / ℃) 45.2 48.0 53.9 44.8 54.8 Transmittance reduction amount (%) after ultraviolet irradiation 0.4 0.9 0.3 0.7 0.5 UV absorption stage (nm) 320 280 310 330 340

TABLE 3

Sample No. 11 12 13 14 15 Glass composition (wt%) SiO2 B2O3 Al2O3 Li2O Na2O K2O ZrO2 CeO2 V2O5 68.1 18.2 2.0 1.1 0.4 8.2 1.0 0.5 0.5 65.4 18.1 8.5 0.7 2.5 3.4 0.8 0.6- 67.8 18.6 3.8 0.9 1.0 7.6 0.3-- 65.0 18.3 8.8 0.5 2.3 4.2 0.9-- 70.8 16.4 4.5 1.2 0.7 6.1 0.3-- Linear expansion coefficient [30 ~ 380 ℃] (X10-7 / ℃) 53.1 44.5 52.5 45.1 47.1 Transmittance reduction amount (%) after ultraviolet irradiation 0.2 1.0 5.8 5.5 5.0 UV absorption stage (nm) 350 330 250 240 240

Each sample of Nos. 1 to 15 shown in the table was produced as follows.

After combining glass raw materials so that it may become a composition shown in the table first, it melt | dissolved at 1550 degreeC for 5 hours using the platinum crucible. After melting, the melt was molded and processed into a predetermined shape to prepare each glass sample, and the coefficient of linear expansion in the temperature range of 30 to 380 ° C. and the spectral transmittance before and after ultraviolet irradiation were measured, and the characteristics were shown in the table. .

As can be seen from the above table, each sample of Nos. 1 to 12, which is an embodiment of the present invention, has a linear expansion coefficient of 44.5 to 54.8x10 ^-7 / deg. C, which is close to that of Kovar, and the transmittance by ultraviolet irradiation. It can be understood that it has a high ultraviolet solarization property since there is almost no drop of 1.0% or less. In addition, it can be seen that the ultraviolet absorption stage is excellent in the ultraviolet absorption effect of 260nm or less which is harmful ultraviolet rays in the range of 280 ~ 350nm.

On the other hand, the samples of Nos. 13 to 15, which are comparative examples, had a linear expansion coefficient in the range of 43 to 55 x 10 ^-7 / deg. C, which can be sealed with the bar, but do not contain any of CeO ₂ and V ₂ O ₅ . Decrease in transmittance by 5% or more, and the ultraviolet ray solarization property was considerably low. In addition, the ultraviolet absorption end of the comparative example is 250 nm or less, indicating that the protection against harmful ultraviolet rays of 260 nm or less is not sufficient.

The coefficient of linear expansion in the table measures the average coefficient of thermal expansion in the temperature range of 30 to 380 ° C. in the dilatometer after processing the glass into a circumference of about 3 mm in diameter and about 50 mm in length.

UV resistance was evaluated as follows. First, both surfaces of 1 mm thick plate glass were mirror polished to obtain a sample. Subsequently, the wavelength of light in which the transmittance of the sample before ultraviolet irradiation showed 80% was measured. In addition, the sample was irradiated with ultraviolet light having a dominant wavelength of 253.7 nm for 60 minutes with a 400 W mercury lamp, and then measured again for the transmittance at a wavelength exhibiting a transmittance of 80% before irradiation. At this time, although the glass which is inferior to ultraviolet-ray solarization property becomes large, the fall of transmittance becomes large, but it is important for glass tubes for fluorescent lamps, such as a liquid crystal backlight, to hardly have this fall. The UV absorber was calculated from the transmittance curve, and the UV blocking effect was evaluated.

As described above, since the glass tube for fluorescent lamps of the present invention is composed of borosilicate glass having high mechanical strength or heat resistance and low dielectric loss, it is possible to cope with thinning and thinning of fluorescent lamps.

Moreover, it is possible to use it for the cold cathode fluorescent lamp which has a linear expansion coefficient of 43-55x10 <^-7> / degreeC, and uses a coba as an introduction metal.

In addition, due to the added ultraviolet ray solarization property is excellent by the added composition, it is difficult to produce ultraviolet coloration, excellent ultraviolet absorption effect, high harmful light blocking effect, and therefore, a narrow-angle fluorescent lamp, especially a liquid crystal display device that is turned on for a long time It is very suitable as an envelope of a cold cathode fluorescent lamp serving as a light source of a lighting device.

In addition, the glass tube for fluorescent lamps of the present invention is further composed of borosilicate glass having high mechanical strength and heat resistance and low dielectric loss, thereby enabling further thinning.

In addition, since the glass tube has a linear expansion coefficient of 43 to 55x10 ^-7 / ° C and is matched with a cobalt, which is an introduction metal, there is no fear of leaks or cracks.

Moreover, since ultraviolet ray solarization property of a glass tube is excellent, it is hard to produce ultraviolet coloring, even if it lights for a long time.

In addition, since it has an excellent ultraviolet absorbing effect and excellent harmful UV blocking ability, it is particularly suitable as a cold cathode fluorescent lamp serving as a light source of a lighting device for a liquid crystal display device.

Claims (4)

CeO ₂ as a sunscreen, At least one selected from Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , Mo ₃ O ₄ , ZnO, PbO, CdO, which is used for preventing solarization, A glass tube for a fluorescent lamp, characterized by consisting of borosilicate glass having a coefficient of linear expansion at 30 to 380 캜 of 43 to 55x10 ^-7 / 캜. CeO ₂ as a sunscreen, At least one selected from Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , NiO, CoO, Mo ₃ O ₄ , ZnO, PbO, CdO for preventing solarization This includes, It consists of borosilicate glass whose linear expansion coefficient in 30-380 degreeC is 43-55x10 <^-7> / degreeC, A glass tube for fluorescent lamps having an outer diameter of 5.2 mm or less and a thickness of 0.6 mm or less and having a tubular shape. The method of claim 1, The borosilicate glass is SiO ₂ 56-74%, B ₂ O ₃ 11-25%, Al ₂ O ₃ 1-10%, Li ₂ O + Na ₂ O + K ₂ O 4-16%, ZrO ₂ by weight percentage 0.1-5%, CeO ₂ 0.1-1%, Sb ₂ O ₃ , Cr ₂ O ₃ , SnO, As ₂ O ₃ , CuO, Fe ₂ O ₃ , Mo ₃ O ₄ , ZnO, PbO, CdO at least selected from A glass tube for fluorescent lamps, each containing at least one composition of 0.1 to 3%. The method according to any one of claims 1 to 3, The glass tube for fluorescent lamps is a glass tube for fluorescent lamps, characterized in that one component of the cold-cathode fluorescent lamp which is the light source of the illumination device of the liquid crystal display element.

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