JPH09106784A - Enclosure for small-diameter fluorescent lamp and small-diameter fluorescent lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an enclosure which makes it possible to manufacture a small-diameter fluorescent lamp exceeding in solarization-resistant property with a Kovar used for a lead metal and a small-diameter fluorescent lamp manufactured by the use thereof. SOLUTION: An enclosure for a fluorescent lamp is structured with a boro- silicate glass including in its glass composition at least one kind among TiO2 , PbO, and Sb2 O3 and having a linear expansion coefficient of 43 to 55×10<-7> / deg.C at 30 to 380 deg.C. A material made of tube-shaped glass having an outer diameter of 5.2mm or less and a thickness of 0.6mm or less is used.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to Kovar (= Westingh
Fe-Ni-Co alloy under the trade name of ouse Ele. Corp.
In the present application, equivalent products of other companies such as KV-2 manufactured by Sumitomo Special Metals Co., Ltd. and KOV manufactured by Toshiba Corporation are also included. ) Is a metal for introducing a small-diameter fluorescent lamp and a small-diameter fluorescent lamp using the same.

[0002]

2. Description of the Related Art Liquid crystal display elements are classified into reflection type liquid crystal display elements that utilize natural light and room illumination light depending on how the light source is used, and transmission type liquid crystal display elements that use a dedicated illumination device, such as backlight light. Broadly divided. Reflective liquid crystal display elements are used for wristwatches and small electronic desk calculators, especially those with low power consumption, but color display by TFT liquid crystal display elements and high-quality display of in-vehicle instruments are required. For such applications, a transmissive liquid crystal display device using a backlight having a fluorescent lamp as a light source is mainly used.

The principle of light emission of a fluorescent lamp for a backlight is as follows.
Similar to general fluorescent lamps for illumination, the phosphor coated on the inner wall surface of the envelope made of tubular glass is excited by the mercury gas enclosed by the discharge between the electrodes and the ultraviolet rays emitted from the excited gas. Emits visible light. However, the major difference from the general-purpose fluorescent lamp is that the outer diameter of the envelope is small and the wall thickness is thin.
Conventionally, lead-soda-type soft glass has been used for the envelope of this fluorescent lamp because of its ease of processing and past results as lighting glass, and cheap Dumet has been used as the introduced metal.

By the way, thinning and lightening of the liquid crystal display element,
With the reduction of power consumption, fluorescent lamps for backlights are required to have a further smaller diameter and thinner wall thickness. However, the smaller diameter of fluorescent lamps structurally reduces the mechanical strength and heat of the lamp. Therefore, the tubular glass, which is the envelope, is required to have higher strength and lower expansion. Further, in order to improve the luminous efficiency, the frequency of the lighting circuit is being increased, and along with this, the tubular glass as an insulator is required to have a low dielectric loss. However, the conventional lead-soda-based soft glass material cannot satisfy these requirements.

Therefore, an envelope for a fluorescent lamp should be manufactured using borosilicate hard glass, which has higher thermal and mechanical strength than lead soda soft glass and is advantageous in terms of low dielectric loss. Was considered. As a result, as a combination of hard glass and metal that can be hermetically sealed, a conventionally known glass for Kovar sealing as an envelope and a fluorescent lamp using Kovar as an introduced metal have been developed and commercialized.

[0006]

However, the envelope of the fluorescent lamp described above is a borosilicate-based Kovar seal that is generally used as a lens for hermetically sealing electronic parts such as electron tubes and photocaps that have been conventionally used. It is said that the worn glass material is used as it is, and it is simply shaped and processed into a thin tube, so when it is lit for a long time, the glass is discolored by the ultraviolet rays emitted from the excited mercury gas (so-called ultraviolet solarization). There will be problems. When the glass is discolored, the brightness is lowered and the emission color is shifted, which causes the liquid crystal display element to be deteriorated in quality such as darkness of display and deterioration of color rendering.

As a countermeasure against this, the inner surface of the glass tube is coated with Al ₂ O ₃ or TiO ₂ , which is a component that reflects or absorbs ultraviolet rays, and a phosphor is applied on top of this to form a multilayer film, which reaches the glass. Although a method of weakening the intensity of ultraviolet rays is partially implemented, this method not only causes an increase in production cost, but also has, for example, an outer diameter of 5.
It is difficult to form a homogeneous multilayer film for a thin tubular glass having a small diameter of 2 mm or less and a wall thickness of 0.6 mm or less. Under such circumstances, there is a strong demand for the development of an envelope for a small-diameter fluorescent lamp, which has resistance to UV solarization.

The present invention has been made in view of the above circumstances, and an envelope for a small-diameter fluorescent lamp, which uses Kovar as an introduced metal and is capable of producing a small-diameter fluorescent lamp excellent in solarization resistance, and An object of the present invention is to provide a small-diameter fluorescent lamp manufactured by using.

[0009]

The envelope for a small-diameter fluorescent lamp of the present invention contains at least one of TiO ₂ , PbO and Sb ₂ O _{3 in} its glass composition and has a linear expansion at 30 to 380 ° C. Borosilicate glass having a coefficient of 43 to 55 × 10 ⁻⁷ / ° C., an outer diameter of 5.2 mm or less, and a wall thickness of 0.6
It is characterized by being made of a tubular glass having a diameter of not more than mm.

Further, the small-diameter fluorescent lamp of the present invention is a small-diameter fluorescent lamp in which Kovar is used as an introduction metal, and contains at least one of TiO ₂ , PbO and Sb ₂ O _{3 in} a glass composition as an envelope. A tubular glass having an outer diameter of 5.2 mm or less and a wall thickness of 0.6 mm or less made of borosilicate glass having a linear expansion coefficient at 30 to 380 ° C. of 43 to 55 × 10 ⁻⁷ / ° C. Characterize.

In the present invention, the envelope is made of borosilicate glass containing at least one of TiO ₂ , PbO and Sb ₂ O _{3 in} the glass composition for the following reason.
In other words, borosilicate glass has high mechanical strength and low expansion as compared with lead-soda-based soft glass, and thus has excellent heat resistance, low dielectric loss, and is easy to reduce the diameter and thickness of a fluorescent lamp. Further, when at least one of TiO ₂ , PbO and Sb ₂ O ₃ is contained in the glass, the UV solarization resistance is high, and coloring is less likely to occur even if the glass is exposed to the UV rays generated inside the fluorescent lamp for a long time.

Further, the reason why the linear expansion coefficient of the borosilicate glass is limited to 43 to 55 × 10 ^-7 / ° C. (30 to 380 ° C.) is that if the linear expansion coefficient is out of this range, it will be This is because the expansion coefficients do not match, slow leaks and cracks occur, and the function as a fluorescent lamp is impaired.

The tubular envelope made of the above borosilicate glass has an outer diameter of 5.2 mm or less, preferably 3.5.
mm or less, wall thickness 0.6 mm or less, preferably 0.5 mm
It has the following sizes, and when the outside diameter and wall thickness are larger than this, it responds to the demand for thinner diameter fluorescent lamps for lighting devices such as backlights due to thinner and lighter liquid crystal display elements. I can't.

The tubular borosilicate glass constituting the envelope has a weight percentage of SiO ₂ 55 to 73% and B _{2
O 3 10~25%, Al 2 O} 3 1~10%, Li 2
O + Na ₂ O + K ₂ O 4-16%, ZrO ₂ 0-5
%, TiO ₂ + PbO + Sb ₂ O ₃ 0.05-11%
Those having the composition of are preferred.

The reason why the content of each component is limited as described above is as follows.

SiO ₂ is a main component necessary for constituting the glass skeleton, and its content is 55 to 73%, preferably 61 to 72%. If the SiO ₂ content is more than 73%, the linear expansion coefficient will be too low and the solubility will be apt to deteriorate, and if it is less than 55%, the chemical durability will be apt to be deteriorated. If it becomes impossible to apply the coating evenly and a burn or the like occurs, the brightness of the fluorescent lamp is lowered.

B ₂ O ₃ is a component necessary for improving the solubility and adjusting the viscosity, and its content is 10 to 25%, preferably 15.2 to 24%. If the content of B ₂ O ₃ is less than 10%, the dissolution becomes difficult and the viscosity becomes too high for sealing Kovar. On the other hand, if it is more than 25%, there arises a problem that the viscosity becomes too low, a homogeneous glass cannot be obtained due to evaporation, and the chemical durability is deteriorated.

Al ₂ O ₃ has a remarkable effect in improving the stability of glass, and its content is 1 to 10%, preferably 1 to 4.9%. When Al ₂ O ₃ is more than 10%, it becomes difficult to melt the glass, and when it is less than 1%, the glass is liable to devitrify, and it becomes difficult to produce a homogeneous glass and stably form it.

Li ₂ O and Na which are alkali metal oxides
₂ O and K ₂ O are components added to facilitate the melting of glass and adjust the expansion coefficient and viscosity, and the total content is 4 to 16%, preferably 5.1 to 13%. Is. If the total amount of these components is 16% or more, the expansion coefficient becomes too high, and the viscosity becomes too low, which is not suitable for Kovar sealing, and causes a drastic decrease in chemical durability. The coefficient becomes too small. The content of each component is 0 to 4% (preferably 0 to 3%) of Li ₂ O,
Na ₂ O 0-4.3% (preferably 0-3.9%),
A range of 0 to 15% (preferably 0 to 13%) of K ₂ O is suitable. Li ₂ O thermal expansion coefficient becomes too high with the tends to deteriorate the devitrification more than 4%, Na ₂ O
If it is more than 4.3%, Na ions may contaminate the phosphor in the heat step during the production of the fluorescent lamp to cause a decrease in brightness, or the coefficient of thermal expansion may become too high. If K ₂ O exceeds 15%, the coefficient of thermal expansion may become too high.

ZrO ₂ is a component that improves chemical durability and prevents alkali blow and burn, and its content is 0.
５5%, preferably 0.01 to 3%. When ZrO ₂ is more than 5%, devitrification deteriorates and the glass becomes nonuniform, resulting in poor dimensional accuracy and appearance defects, making it difficult to obtain high-quality glass.

TiO ₂ , PbO and Sb ₂ O ₃ are all components which impart a high resistance to UV solarization to the glass, and the total amount is 0.05 to 11%, preferably 0.1 to 5.5%. Is. If the total amount of these components exceeds 11%, the effects of devitrification and evaporation of the glass become strong, and it becomes difficult to obtain a tubular glass that is homogeneous and has good dimensional accuracy. On the other hand, 0.
If it is less than 05%, there is almost no effect. TiO ₂
When containing as an essential component, the content of each component is TiO
₂ 0.05-5% (preferably 0.1-3%), Pb
O 0-10% (preferably 0-5.5%), Sb ₂ O
_{It is 30 to} 4% (preferably 0 to 1%). When PbO is contained as an essential component, the content of each component is TiO ₂
0-5% (preferably 0-2%), PbO 0.05
-10% (preferably 0.1-5.5%), Sb ₂ O ₃
A range of 0 to 4% (preferably 0 to 1%) is suitable. When Sb ₂ O ₃ is contained as an essential component, the content of each component is TiO ₂ 0 to 5% (preferably 0 to 2).
%), PbO 0-10% (preferably 0-5.5)
%), Sb ₂ O ₃ 0.1-4% (preferably 0.2-)
1%). In any case, if the amount of TiO ₂ exceeds a predetermined amount, the glass itself tends to be colored, and the devitrification property deteriorates sharply, making it difficult to obtain a transparent and homogeneous glass. Pb
When the amount of O exceeds a predetermined amount, the glass itself is likely to be colored as in the case of TiO _2, and it is difficult to obtain a homogeneous glass by evaporating at the time of melting, which is unfavorable for the environment. When Sb ₂ O ₃ exceeds a predetermined amount, it becomes difficult to obtain a homogeneous glass.
Further, when PbO or Sb ₂ O ₃ is excessively contained in the glass, the glass is colored brown or black due to thermal processing in the manufacturing process of the fluorescent lamp, and the appearance quality is deteriorated. Moreover, coloring of the effective light emitting portion directly leads to a decrease in luminance, which is not preferable.

Further, the above borosilicate glass is SrO, BaO, CaO, MgO, ZnO, P ₂ O for the purpose of adjusting the viscosity of the glass and improving the weather resistance, the solubility and the clarity.
It is possible to add an appropriate amount of components such as ₅ , As ₂ O ₃ , SO ₃ , F ₂ , Cl _{2 and the} like.

[0023]

Embodiments of the present invention will be described below. The following description shows an example of the present invention, and the present invention is not limited to this.

The envelope for a thin fluorescent lamp of the present invention is manufactured as follows.

First, glass raw materials are prepared so as to have a desired composition. For example, by weight percentage SiO ₂ 55-73
%, B ₂ O ₃ 10-25%, Al ₂ O ₃ 1-10
%, Li ₂ O + Na ₂ O + K ₂ O 4-16%, ZrO
_{2 0~5%, TiO 2 + PbO} + Sb 2 O 3 0.0
It is prepared so as to have a composition of 5 to 11%. Next, the prepared glass raw material is put into a glass melting furnace, and 1500 to 16
After being melted at 50 ° C. and vitrified, it is formed into a tubular shape by a tube drawing method such as a Dunner method or a down draw method, and cut into a predetermined length. At this time, it may be directly molded so as to have a desired outer diameter and wall thickness, or a parent tube having a large outer diameter and wall thickness may be produced and then thinned by a redraw method. In this way, the linear expansion coefficient is 43 to 55 × 10 ^-7 /
Thus, the envelope for a thin fluorescent lamp of the present invention, which is made of tubular glass made of borosilicate glass having an outer diameter of 5.2 mm or less and a wall thickness of 0.6 mm or less, can be obtained. It should be noted that, if necessary, processing such as forming a reduced diameter portion at both ends of the tubular glass may be performed.

Next, the thin fluorescent lamp of the present invention will be described.

The small-diameter fluorescent lamp of the present invention uses the envelope manufactured as described above, and the introduction metal made of Kovar is hermetically sealed in a state of being inserted into both ends of the envelope. In addition, a gas such as mercury or xenon is enclosed inside, and the inner wall surface of the envelope is coated with a phosphor. Then, when a voltage is applied, a discharge occurs between the electrodes at the tips of the respective introduced metals, and the gas such as mercury and xenon that is enclosed is excited by this discharge, and the ultraviolet rays emitted from the excited gas cause the inner wall surface of the envelope to be excited. The phosphor emits visible light.

Such a small-diameter fluorescent lamp is used by being incorporated in a lighting device for a liquid crystal display device or the like.

[0029]

EXAMPLES The linear expansion coefficient and ultraviolet solarization resistance of the envelope for a thin fluorescent lamp of the present invention will be evaluated below.

Tables 1 to 4 show examples (Sample Nos. 1 to 18) and comparative examples (Samples No. 19 and 20) of borosilicate glass constituting the envelope of the present invention.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

No. shown in the table. Each sample of 1 to 20 was prepared as follows.

First, glass raw materials were prepared so as to have the composition shown in the table and then melted at 1550 ° C. for 5 hours using a platinum crucible. After melting, the melt was molded into a predetermined shape and processed to prepare each glass sample, and the linear expansion coefficient in the temperature range of 30 to 380 ° C. and the spectral transmittance before and after irradiation with ultraviolet rays were measured, and each characteristic was measured. Is shown in the table.

As is apparent from the table, No. 1 which is an embodiment of the present invention. Each of the samples 1 to 18 has a linear expansion coefficient of 45.3.
˜54.4 × 10 ⁻⁷ / ° C., which is similar to that of Kovar and the decrease in transmittance due to ultraviolet irradiation is 1.0
It can be understood that it has a high resistance to UV solarization because it is almost not more than%.

On the other hand, No. 19 and 2
The sample of 0 has a coefficient of linear expansion that can be sealed with Kovar. 4
Within the range of 3 to 55 × 10 ⁻⁷ / ° C., but TiO ₂ , P
Since neither bO nor Sb ₂ O ₃ was contained at all, the decrease in transmittance due to ultraviolet irradiation was as large as 7% or more, and the ultraviolet solarization resistance was very low.

The linear expansion coefficient in the table is obtained by processing glass into a cylinder having a diameter of about 3 mm and a length of about 50 mm, and then measuring the average coefficient of linear expansion in the temperature range of 30 to 380 ° C. with a self-recording differential thermal dilatometer. It was done.

The UV solarization resistance was evaluated as follows. First, both sides of 1 mm-thick plate glass were mirror-polished to obtain a sample. Then, the wavelength of light showing a transmittance of the sample of 80% before ultraviolet irradiation was measured. Furthermore, the main wavelength of the sample was 253.7 using a 40 W low-pressure mercury lamp.
After irradiating 60 nm UV for 60 minutes, the transmittance is 8 before irradiation.
By measuring the transmittance again at the wavelength showing 0%, the decrease of the transmittance due to the irradiation of ultraviolet rays was obtained. At this time, the lower the transmittance of the glass is, the greater the deterioration of the UV solarization resistance is. However, it is important for a glass tube for a fluorescent lamp such as a liquid crystal backlight to have almost no such decrease.

[0041]

As described above, since the envelope for a small-diameter fluorescent lamp of the present invention is made of borosilicate glass having high mechanical strength and heat resistance and a small dielectric loss, the small-diameter fluorescent lamp has a small diameter. It is possible to cope with thinning and thinning. 43
It has a coefficient of linear thermal expansion of ˜55 × 10 ⁻⁷ / ° C. and can be used for a fluorescent lamp using Kovar as an introduced metal. In addition, since it has excellent solarization resistance, it is less likely to cause ultraviolet coloring. Therefore, it is suitable as an envelope of a small-diameter fluorescent lamp that is turned on for a long time, particularly a small-diameter fluorescent lamp that serves as a light source of a liquid crystal display element lighting device.

Further, since the small-diameter fluorescent lamp of the present invention has the envelope made of borosilicate glass having high mechanical strength and heat resistance and small dielectric loss, the diameter can be further reduced. . Moreover, since the envelope has a linear thermal expansion coefficient of 43 to 55 × 10 ⁻⁷ / ° C. and is matched with Kovar as the introduced metal, there is no possibility of causing slow leak or crack. Moreover, since the enclosure has excellent solarization resistance, it is less likely to be colored with ultraviolet rays even when it is turned on for a long time. Therefore, it is particularly suitable as a small-diameter fluorescent lamp that serves as a light source of a lighting device for a liquid crystal display element.

Claims (12)

[Claims] 1. A borosilicate glass containing at least one of TiO ₂ , PbO and Sb ₂ O _{3 in} a glass composition and having a linear expansion coefficient at 30 to 380 ° C. of 43 to 55 × 10 ⁻⁷ / ° C. The configured outer diameter is 5.2 mm or less and the wall thickness is 0.
An envelope for a small-diameter fluorescent lamp, which is made of tubular glass of 6 mm or less. 2. The borosilicate glass comprises, in weight percentage, S
iO ₂ 55-73%, B ₂ O ₃ 10-25%, Al
₂ O ₃ 1-10%, Li ₂ O + Na ₂ O + K ₂ O 4
~ 16%, ZrO ₂ 0-5%, TiO ₂ + PbO + S
b ₂ O ₃ 0.05~11% of the small-diameter fluorescent lamp envelope of claim 1, characterized in that it comprises a composition. 3. TiO ₂ is 0.05 to 5% and PbO is 0.
The envelope for a small-diameter fluorescent lamp according to claim 1 or 2, wherein Sb ₂ O ₃ is 10% and Sb ₂ O ₃ is 0-4%. 4. TiO ₂ is 0 to 5% and PbO is 0.05.
The envelope for a small-diameter fluorescent lamp according to claim 1 or 2, wherein Sb ₂ O ₃ is 10% and Sb ₂ O ₃ is 0-4%. 5. TiO ₂ is 0 to 5% and PbO is 0 to 10.
%, Sb ₂ O ₃ is 0.1 to 4%, and the envelope for a small-diameter fluorescent lamp according to claim 1 or 2. 6. The envelope for a small-diameter fluorescent lamp according to claim 1, which is used for a small-diameter fluorescent lamp which is a light source of an illuminating device for a liquid crystal display element. 7. A small-diameter fluorescent lamp using Kovar as an introduction metal, wherein TiO ₂ , PbO, Sb _{2 is used} as an envelope.
_{30 to 3} containing at least one of O _{3 in} the glass composition
A tubular glass having an outer diameter of 5.2 mm or less and a wall thickness of 0.6 mm or less, which is made of borosilicate glass having a linear expansion coefficient at 80 ° C. of 43 to 55 × 10 ⁻⁷ / ° C. A small diameter fluorescent lamp. 8. The borosilicate glass comprises, in weight percentage, S
iO ₂ 55-73%, B ₂ O ₃ 10-25%, Al
₂ O ₃ 1-10%, Li ₂ O + Na ₂ O + K ₂ O 4
~ 16%, ZrO ₂ 0-5%, TiO ₂ + PbO + S
thin fluorescent lamp of claim 7, characterized in that it has a b ₂ O ₃ 0.05~11% of the composition. 9. TiO ₂ is 0.05 to 5% and PbO is 0.
The small-diameter fluorescent lamp according to claim 7, wherein Sb ₂ O ₃ is 0 to 4% and Sb ₂ O ₃ is 0 to 4%. 10. TiO ₂ is 0 to 5% and PbO is 0.0.
5-10%, small diameter fluorescent lamp of claim 7 or 8 Sb ₂ O ₃ is equal to or is 0-4%. 11. TiO ₂ is 0 to 5% and PbO is 0 to 1.
The small-diameter fluorescent lamp according to claim 7 or 8, wherein 0% and Sb ₂ O ₃ are 0.1 to 4%. 12. The small-diameter fluorescent lamp according to claim 7, which is used as a light source of a lighting device for a liquid crystal display device.