JP2006114384A - Envelope for external electrode fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an envelope for an external electrode fluorescent lamp whose dielectric loss is small and whose dielectric capacity variation is hardly generated. <P>SOLUTION: The envelope for an external electrode fluorescent lamp used for manufacturing the external electrode fluorescent lamp having a structure in which electrodes are installed on the outer surface thereof is composed of glass having a dielectric loss tangent of 0.02 (not including 0.02) to 0.2 at 40 kHz at 250°C and a strain point of ≤650°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a jacket for an external electrode fluorescent lamp serving as a light source of an illumination device such as a liquid crystal display element.

  Since liquid crystal display elements do not self-emit, a dedicated lighting device (hereinafter referred to as a backlight unit) may be used when used in applications such as notebook computers, TV monitors, personal computer (PC) monitors, and in-vehicle instruments. Widely done.

  A fluorescent lamp serving as a light source of a conventionally used backlight unit uses a compact and long-life cold-cathode tube, and its light emission principle is the same as that of a general illumination fluorescent lamp. That is, electric power is supplied to the internal electrodes via a jumet wire, Kovar metal, tungsten metal, etc. enclosed in a glass jacket, and a discharge is caused between the electrodes. The discharge between the electrodes excites mercury (Hg) and xenon (Xe) sealed in the outer container, and radiates ultraviolet rays. The phosphor coated on the inner wall surface of the outer container emits visible light by the emitted ultraviolet light. In order to control the amount of current during emission of the fluorescent lamp, the cold cathode tube unit is composed of an inverter that increases the voltage for each lamp and a capacitor that controls the current.

  In recent years, liquid crystal display devices have become larger, and accordingly, a plurality of cold cathode tubes have been used in the backlight unit in order to ensure sufficient brightness. For example, a TV monitor mainly uses a backlight unit that emits light uniformly by arranging a plurality of fluorescent lamps on the back side of a liquid crystal display device at intervals of about 1 to 5 cm and emitting light through a diffusion plate. In such a display device, as many power supplies as the number of lamps are mounted, the volume occupied by the power supply in the device increases, and it is difficult not only to reduce the thickness of the display device but also to increase the price. Therefore, it is expected to integrate the power supply of the unit into one, but it was impossible in the past because the capacitor cannot be omitted.

  In the conventional cold cathode lamp, the metal electrode reacts with Hg during lighting to form an alloy and consumes Hg. Since Hg is a component that contributes to light emission, the cold-cathode lamp gradually becomes dark and eventually cannot withstand use. Thus, although there is a limit in the lifetime of the cold cathode tube, it cannot be said that the lifetime is sufficiently long for a TV monitor.

  Under such circumstances, an external electrode fluorescent lamp (EEFL) in which there is no internal electrode that tends to affect the life and electrodes are arranged in the vicinity of both ends of the outer surface of the lamp mantle tube has been studied. (For example, Patent Document 1 and Non-Patent Document 1) There is also a flat-type external electrode lamp having a plurality of discharge spaces. (For example, Patent Documents 2 and 3)

The method of supplying power to the lamp of the external electrode fluorescent lamp is not to emit electrons directly from the electrode as in the case of a cold cathode lamp, but the glass portion of the glass outer tube functions as a dielectric, and the inner surface of the tube depends on its dielectric characteristics. From which electrons are emitted. In other words, an alternative mechanism for the condenser is constructed using the lamp mantle. As a result, no capacitor is required and power supply can be integrated. The basic light emission principle is to generate ultraviolet rays by Hg or Xe to illuminate the phosphor as in the conventional fluorescent lamp.
JP2002-8408 Special table 2002-508574 JP 2000-156199 A Journal of the Illuminating Society of Japan vol. 87 no. 1 2003 p18

The outer container of the external electrode fluorescent lamp is required to have the following characteristics.
(1) The dielectric loss is small.
The amount of heat generated by the dielectric loss represents the energy loss of the capacitor, and is a function of the product of the dielectric loss tangent, the dielectric constant, the square of the electric field strength, and the frequency, as shown in the following equation.

P = k × f × ε × tan δ × E ² − Equation 1
[P: dielectric loss k: constant f: frequency ε: dielectric constant tan δ: dielectric loss tangent E: strength of electric field (E is proportional to voltage V if the shape of the capacitor is the same)]

  As this increases, energy loss increases, and as a result of being released as thermal energy, the dielectric (outer container) itself generates heat. The generation of thermal energy is a disadvantage in the environment because it deteriorates the efficiency of the lamp.

  Moreover, the driving temperature of a normal fluorescent lamp rises from room temperature due to internal loss. However, in the external electrode fluorescent lamp, when the temperature of the electrode portion of the outer container increases, the dielectric loss of the glass constituting the outer container increases, and the glass itself starts to generate heat, and this heat generation further increases the dielectric loss of the glass. It falls into a vicious circle. As a result, there is a risk of causing a fire in the organic members around the lamp. In particular, the liquid crystal backlight unit is surrounded by an organic substance such as a reflector or a liquid crystal panel, so that the generated heat is difficult to dissipate and the ambient temperature of the lamp is likely to rise. For this reason, it is necessary to consider the heat dissipation of the lamp, and a heat dissipation device is required, or the lamp output cannot be increased. As a result, various restrictions arise when used for the light source of a large liquid crystal display device.

  In addition, when the dielectric loss is large, slight temperature fluctuation of the electrode portion causes a local temperature rise, which causes the above-mentioned problem, and the glass melts locally, and the lamp is perforated and the lamp is stopped.

(2) There is no variation in dielectric capacitance (capacitance).
The external electrode fluorescent lamp uses a glass outer casing as a dielectric to supply electric power, so that the dielectric capacity determines the amount of electric power supplied to the lamp. Since the dielectric capacitance depends on the thickness of the dielectric, that is, the thickness of the outer container, the thickness variation of the dielectric portion is required to be as small as possible.

  As described above, the external electrode fluorescent lamp does not have an electrode inside, and the tube-type external electrode lamp has a structure having an electrode on the outer peripheral surface of the outer casing. As shown in FIG. 5, it has a mechanism similar to a capacitor in which the thickness of glass is a dielectric, one electrode is an external electrode, and the other electrode is Hg vapor or Xe inside the lamp. When a plurality of lamps L1 and L2 are connected to one power source 20, the voltage is equal for each lamp.

  The flat external electrode lamp has a structure having electrodes on the outer surface of the lamp on the opposite side from which light is extracted. As shown in FIG. 31, it has the same mechanism as a condenser in which the thickness of the plate glass indicated by hatching is a dielectric, one pair of electrodes is an external electrode, and the other electrode is Hg vapor or Xe inside the lamp. .

  Electric power is supplied to the lamp by driving the condenser mechanism with an AC power source. The brightness of the lamp is determined by the electric energy, and the electric energy (electric charge) of the capacitor is obtained by the capacitance and voltage (below).

Q = C × V − Formula 2
[Q: charge C: capacitance V: terminal voltage]
Since the voltage of the tube-type external electrode lamp is the same for each lamp, it can be said that the capacitance determines the amount of power. Even in a flat external electrode lamp, the glass thickness of the electrode portion determines the capacitance. Capacitance is the product of the reciprocal of dielectric constant, area and thickness. (Following formula)
C = ε × S × (1 / d) −Formula 3
[C: Capacitance ε: Dielectric permittivity S: Electrode area d: Dielectric thickness]
Here, it can be seen that the dielectric thickness (= the thickness of the outer container) is an important factor for determining the capacitance. In other words, since the amount of charge increases as the outer container wall thickness is thinner, the lamp becomes brighter. Conversely, as the wall thickness increases, the amount of charge decreases and the lamp becomes dark. Therefore, in a backlight unit having a structure in which a plurality of tubular external electrode lamps are connected to a single power source, in order to suppress variations in brightness between the lamps, and in a box-shaped external electrode lamp, the brightness of the electrode portion is reduced. In order to suppress the variation, it is extremely important that the thickness of the lamp envelope is uniform.

  However, the outer electrode fluorescent lamp envelope used at present is merely a diversion of a normal fluorescent lamp envelope, and the above required characteristics are not fully considered.

  An object of the present invention is to provide a jacket for an external electrode fluorescent lamp which has a small dielectric loss and hardly causes variations in dielectric capacitance.

  As a result of various studies, the present inventor has found that the above-described object can be achieved by producing a mantle container with a glass having a small dielectric loss tangent and excellent moldability, and proposes the present invention. .

  In other words, the outer electrode fluorescent lamp envelope of the present invention is an outer electrode fluorescent lamp envelope used for manufacturing an external electrode fluorescent lamp having a structure in which an electrode is provided on the outer surface. It is characterized by being made of glass having a tangent of 0.02 (excluding 0.02) to 0.2 and a strain point of 650 ° C. or lower.

  The “outer container” in the present invention includes various shapes such as a tube shape and a planar shape, and is used as a member for forming a discharge space of a fluorescent lamp or an enclosure.

  Since the outer electrode fluorescent lamp envelope of the present invention has a small dielectric loss tangent, the dielectric loss is small compared to the conventional glass, and the efficiency of the lamp is good. Moreover, since local heating hardly occurs, the reliability is high. For this reason, the external electrode fluorescent lamp manufactured using the outer casing of the present invention does not need to install a heat dissipation device or restrict the lamp output.

  Further, the glass constituting the outer container of the present invention has a low strain point and a wide molding temperature range or processing temperature range, and thus has excellent moldability and workability. Therefore, it is easy to form the outer container to a constant thickness, and variations in the dielectric capacitance between lamps or in the lamps are less likely to occur. For this reason, in the external electrode fluorescent lamp using the outer casing of the present invention, there is no difference in brightness between lamps or in the lamp, and display unevenness does not occur.

  In addition, since it is made using glass having excellent moldability, in the case of a tubular outer container, the roundness is high and the tube is not bent. Generally, a fluorescent lamp used for a backlight unit or the like has a small diameter, and thus it is difficult to apply a phosphor. For this reason, when the roundness of the tube is poor, phosphor coating unevenness tends to occur. Moreover, since the lamp length is long for a thin tube diameter, a slight bending of the tube becomes conspicuous. However, since the outer container of the present invention has a high roundness and no bending of the tube, there is an effect that the above-described problem hardly occurs.

  On the other hand, since the flat outer casing is excellent in workability, press molding of a front plate or the like is easy, and each discharge space can be formed accurately. For this reason, the variation in the brightness for each discharge space hardly occurs.

  The outer electrode fluorescent lamp envelope of the present invention is made of glass having a small dielectric loss tangent.

  The dielectric loss that affects the heat generation of glass is proportional to the product of dielectric loss tangent, voltage, dielectric constant and frequency. The voltage and frequency of the power supply are constant depending on the power supply conditions. If a lamp having the same electrode area and glass thickness is made to have a constant brightness, the value of the product other than the dielectric loss tangent in Equation 1 becomes constant, so the dielectric loss tangent is an important factor determining the dielectric loss. . The dielectric loss tangent is largely governed by the influence of the ionic conduction of the glass at a frequency of about 100 kHz or less used in a fluorescent lamp. Since the ionic conduction of glass tends to increase rapidly as the temperature rises, the dielectric loss tangent increases as the temperature rises.

  Next, the dielectric loss tangent of the glass constituting the outer container of the present invention will be described in detail.

  Fluorescent lamps are used at 40 KHz to 100 KHz, but the dielectric loss tangent tends to decrease with increasing frequency. In other words, the dielectric loss tangent at 40 KHz is higher than that at 100 KHz. Therefore, the dielectric property of the glass for an outer container can be defined by a value of 40 KHz. The dielectric loss tangent values at 150 ° C., 250 ° C., and 350 ° C. are shown below. Note that 150 ° C. corresponds to the normal operating temperature of the lamp, and 250 ° C. corresponds to a temperature that may occur inside the lamp. Furthermore, 350 ° C. is a temperature that should be considered from the viewpoint of safety. In the present invention, the value at 250 ° C., which is the maximum temperature conceivable for a fluorescent lamp, is recognized as being most important, and this value is emphasized.

  The dielectric loss tangent at 150 ° C. and 40 kHz is preferably larger than 0.005 and not larger than 0.05. In particular, it is desired to be 0.02 or less, and further 0.01 or less. If it is 0.05 or less, the dielectric loss becomes small, and it becomes possible to suppress the amount of generated heat to a level that does not cause a problem in practical use. Furthermore, if it is 0.01 or less, even a high output type fluorescent lamp is preferable because heat generation is reduced.

  The dielectric loss tangent at 250 ° C. and 40 kHz is greater than 0.02 and less than or equal to 0.2. Preferably it is 0.1 or less, More preferably, it is 0.05 or less. If it is 0.2 or less, the dielectric loss becomes small, and it becomes possible to suppress the calorific value to a level at which there is no problem in practical use, and if it is 0.1 or less, it can be used even at a lamp operating temperature high. If it is 05 or less, it is possible to use even a type with high heat generation such as a high output type fluorescent lamp, which is preferable.

  The dielectric loss tangent at 350 ° C. and 40 kHz is preferably greater than 0.1 and 2 or less. In particular, it is preferably 1 or less, more preferably 0.5 or less. If it is 2 or less, the dielectric loss becomes small, the heat generation of the electrode can be suppressed, and the heat generation amount can be suppressed to a level that does not cause a problem in actual use. A lamp having a high lamp operating temperature can be used if it is 1 or less, and if it is 0.5 or less, a high output type lamp can be used even in an environment where the ambient temperature is high and heat radiation is difficult.

  The dielectric property of 1 MHz is a value representative of the properties of the substance. In the present invention, a glass having a dielectric loss tangent at 1 MHz of 0.003 or less, particularly 0.0025 or less, and further 0.002 or less at room temperature is used. It is preferable. If it is 0.003 or less, the dielectric loss becomes small, and the amount of generated heat can be suppressed to a level that does not cause a problem in practical use. If it is 0.025 or less, a lamp having a high operating temperature can be used. Furthermore, if it is 0.002 or less, the heat generation is reduced even in a high output type or high frequency type lamp, which is preferable.

  In the tube type external electrode lamp, light cannot be extracted from the electrode metal portion, so the electrode needs to be made as small as possible, and as a result, the drive voltage must be increased. On the other hand, in a flat external electrode lamp, a large electrode can be formed on a back plate that is not related to light extraction efficiency. Therefore, the driving voltage is lowered as compared with a tube external electrode lamp. Can do. In other words, the allowable range of the dielectric loss tangent of glass is larger in the flat lamp. Therefore, when the envelope of the present invention is used for a tube-type external electrode lamp, it is necessary to consider the lamp design. On the other hand, when it is used for a flat type external electrode lamp, it can be used without any particular restriction.

  Further, it is desirable that the dielectric loss tangent change rate represented by the following formula is 0.002 or less, preferably 0.001 or less, and more preferably 0.0005 or less, as an average value between 150 ° C. and 250 ° C. If it is 0.002 or less, even if the lamp ambient temperature rises, it can be used at a stable temperature with little change in lamp heat generation. If it is 0.001 or less, the influence of the external environment of the lamp is reduced, and 0.0005 or less. Then, the lamp can be used with high reliability even in a high temperature atmosphere.

  Further, it is desired that the dielectric loss tangent change rate represented by the following formula is 0.01 or less, preferably 0.008 or less, more preferably 0.004 or less, as an average value between 250 ° C. and 350 ° C. If it is 0.01 or less, abnormal heat generation due to an increase in dielectric loss accompanying a temperature rise can be suppressed, so that abnormal heating of the outer casing can be prevented. If it is 0.008 or less, more preferably 0.004 or less, abnormal heating of the mantle container is unlikely to occur even under conditions where heat dissipation from the lamp is limited.

Dielectric loss tangent change rate = ΔDielectric loss tangent / ΔT
[△ Dielectric loss tangent: Difference in dielectric tangent △ T: Difference in measurement temperature (° C) of dielectric properties]
In order to reduce the dielectric loss tangent of the glass, ion conduction may be made difficult to occur compositionally. Specifically, it can be adjusted by reducing the alkali component, adjusting the proportion of the alkali component, or limiting the amount of water. Further, since low alkali or non-alkali glass has a low dielectric loss tangent, the outer container may be made of this type of glass when a low dielectric loss tangent is particularly required. However, since this type of glass tends to have high viscosity, formability and workability may be inferior.

  The glass constituting the outer container of the present invention preferably has a desired dielectric constant in addition to the above-described dielectric loss tangent. That is, the dielectric capacitance is determined by the product of the dielectric constant and the voltage. Therefore, if the dielectric constant of the glass is high, the driving voltage can be lowered, the insulating material around the lamp can be reduced, and the conductive loss due to the volume resistance of the glass can be reduced. The dielectric constant will be specifically described below.

  The dielectric constant at 150 ° C. and 40 kHz is preferably 5 or more. In particular, it is desired to be 6 or more, and further 7 or more. If it is 5 or more, the necessary electric capacity can be secured while suppressing the practical electrode area and the lamp driving voltage. If it is 6 or more, it is more preferable, and if it is 7 or less, a high output type fluorescent lamp However, it can be used and is preferable.

  The dielectric constant at 250 ° C. and 40 kHz is preferably 5 to 13, particularly 6 to 11, and more preferably 7 to 10. If it is 5 or more, the necessary electric capacity can be secured while suppressing the practical electrode area and the lamp driving voltage. If it is 6 or more, it is more preferable, and if it is 7 or less, a high output type fluorescent lamp However, it can be used and is preferable. If it is 13 or less, it becomes a standard that there is no abnormality as a glass dielectric, and if it is 11 or less and further 10 or less, the variation in the electrode becomes small, which is preferable.

  The dielectric constant at 350 ° C. and 40 kHz is preferably 5 to 22, particularly 6 to 15, and more preferably 7 to 12. If it is 5 or more, the necessary electric capacity can be secured while suppressing the practical electrode area and the lamp driving voltage. If it is 6 or more, it is more preferable, and if it is 7 or less, a high output type fluorescent lamp However, it can be used and is preferable. If it is 22 or less, it becomes a standard that there is no abnormality in the glass dielectric, and if it is 15 or less and 12 or less, the variation in the electrode is preferably reduced.

  Further, it is preferable to use a glass having a dielectric constant at 1 MHz of 5 or more, particularly 6 or more, more preferably 7 or more at room temperature. If it is 5 or more, the dielectric loss becomes small, and the amount of heat generation can be suppressed to a level that does not cause a problem in practical use. If it is 6 or less, a lamp having a high lamp operating temperature can be used. Further, if it is 7 or more, heat generation is reduced even in a high output type or high frequency type lamp, which is preferable. 10 or less is preferable because there is no variation because there is no abnormality as a glass dielectric.

  Moreover, it is desirable that the dielectric constant change rate represented by the following formula is an average value between 150 ° C. and 250 ° C., 0.04 or less, particularly 0.02 or less, and further 0.01 or less. If it is 0.04 or less, even if the lamp ambient temperature rises, it is possible to prevent charge concentration due to variations in the dielectric constant in the electrode to prevent local heating, and more preferably 0.02 or less, If it is 0.01 or less, the influence of the lamp driving voltage is reduced, which is extremely ideal.

  Moreover, it is desirable that the dielectric loss tangent change rate represented by the following formula is an average value between 250 ° C. and 350 ° C. of 0.1 or less, particularly 0.05 or less, and further 0.02 or less. If it is 0.1 or less, abnormal heat generation due to variations in dielectric constant accompanying temperature rise can be suppressed, and local heating of the jacket can be prevented. If it is 0.05 or less, it is more preferable, and local heating of the mantle container is less likely to occur even under conditions where heat dissipation from the lamp is limited.

Dielectric constant change rate = △ Dielectric constant / △ T
[Δ dielectric constant: difference in dielectric constant Δ T: difference in measurement temperature (° C.) of dielectric properties]
In order to reduce the change in the dielectric constant of the glass, ion conduction may be made difficult to occur compositionally. Specifically, it can be adjusted by introducing an alkaline earth component to reduce the alkali component or adjusting the ratio of the alkali component.

  The glass constituting the outer electrode fluorescent lamp envelope of the present invention is excellent in formability and workability, and can be accurately formed into a tubular shape, a plate shape, or the like. The glass member formed into a plate shape is used as it is as a back plate or the like, or is further subjected to press processing or the like for use in a front plate or the like, and is used for the production of a flat outer container. .

  The formability of glass depends on whether it has viscosity characteristics suitable for the molding method. For example, glass that is formed into a tubular shape is usually formed by tube drawing by a method such as the Danner method, the down draw method, or the up draw method. Further, the glass formed into a plate shape is formed by drawing by a method such as an overflow method, a float method, or a slot down method. For this reason, it is better that the viscosity change of the glass with respect to the temperature is gentle (long glass) in the molding temperature range. In particular, in an outer electrode fluorescent lamp envelope used for a lighting device application of a liquid crystal display element as in the present invention, in the case of a tube type, the tube glass has a thin and thin diameter. In addition, since restrictions on roundness, eccentricity of the inner diameter and thickness variation are severe, it is necessary for the glass to have a sufficiently gentle viscosity change with respect to temperature in order to perform precision molding. Also in the case of a flat type, high flatness and uniform wall thickness are required.

  Therefore, in the present invention, the strain point at which the glass is almost solid is used as a guide. That is, the lower the strain point, the larger the temperature difference from the actual molding temperature, so that a so-called long glass is obtained. Specifically, glass having a temperature of 650 ° C. or lower, preferably 600 ° C. or lower is used. If the strain point is 650 ° C. or lower, the viscosity of the glass does not change suddenly, and it becomes easy to obtain viscosity characteristics suitable for tube drawing or plate drawing. Furthermore, if it is 600 degrees C or less, it will become possible to reduce the glass forming temperature.

For the same reason, it is desired that the difference between the strain point and the temperature corresponding to 10 ⁴ dPa · S is 400 ° C. or higher, preferably 450 ° C. or higher, particularly 500 ° C. or higher, and more preferably 550 ° C. or higher. If this temperature difference is 400 ° C. or more, it becomes possible to obtain a tube glass with good dimensional accuracy, and if it is 450 ° C. or 500 ° C. or more, a tube glass with good dimensional accuracy can be easily obtained. If it is 550 degreeC or more, it will become possible to raise a shaping | molding speed, maintaining a high dimensional accuracy.

  Moreover, when the glass forming temperature is high, not only special heat-resistant bricks and Pt are required, but also the amount of energy used is increased from the environmental viewpoint, which is not preferable. Therefore, it is desirable that the temperature corresponding to the viscosity (103 dPa · S) at the start of the tube drawing be 1400 ° C. or lower. Similarly, it is desirable that the temperature corresponding to the processing viscosity (104 dPa · S) of the lamp is 1200 ° C. or less.

In addition, when crystals are formed during molding, the viscosity around the crystals changes, resulting in a difference in the elongation of the glass, making it difficult to obtain tube glass or plate glass with good dimensional accuracy. The liquid phase viscosity of glass represents the ease of crystal generation of glass. It can be said that the larger the value is, the less the crystal is generated even with a large viscosity. In the present invention, the liquid phase viscosity is preferably 10 ⁴ dPa · S or more, more preferably 10 ^4.5 dPa · S or more, and even more preferably 10 ⁵ dPa · S. If it is 10 ⁴ dPa · S or more, there is no hindrance to the forming of tubes and plates, and if it is 10 ^4.5 dPa · S or more, improvement in mass productivity can be expected. If it is 10 ⁵ dPa · S or more, it is possible to efficiently form a tube glass or the like with good dimensional accuracy without special consideration for the molding equipment.

  In the case of a flat-type lamp envelope, for example, constituent members such as a front plate are used by processing plate glass into a bento case type or corrugated plate. This processing is performed by pressing the glass at a temperature near the softening point. In order to improve the workability, it is desired that the glass has a long viscosity in the processing temperature range. In the present invention, the glass constituting the outer container has a low strain point, and therefore has a large temperature difference from the actual processing temperature, and is a long glass, so that the workability is good. Specifically, the temperature difference between the softening point and the strain point is desired to be in the range of 150 to 400 ° C, particularly 220 to 300 ° C. If this temperature difference is 150 ° C. or more, the above-described effect appears. Moreover, if it is within 400 degreeC, it can shape | mold, without raising a shaping | molding temperature extremely.

In order to make the viscosity characteristics of the glass long, the content of alkaline components such as Li ₂ O, Na ₂ O, K ₂ O and B ₂ O ₃ is increased, the content of SiO ₂ and Al ₂ O ₃ is decreased, This can be achieved by increasing the amount of moisture. In addition, the liquid phase viscosity of the glass can be increased by optimizing the content of alkaline earth components such as MgO, CaO, SrO, BaO, ZnO, Al ₂ O ₃ and the ratio of these components. is there.

  The moisture contained in the glass has a function of reducing the low-temperature viscosity of the glass and improving the workability of the lamp. However, there is a problem that the dielectric loss tangent increases as the amount of moisture increases. Further, when emitted as gas into the lamp, the brightness of the lamp decreases. Furthermore, it becomes a cause of a bubble defect.

  For this reason, it is preferable to properly manage the water content. Specifically, if the coefficient X obtained by the following equation is 0.8 or less, the above problem is unlikely to occur. Moreover, if it is 0.1 or more, it becomes easy to form glass with high accuracy. A suitable range for the coefficient X is 0.15 to 0.6, in particular 0.2 to 0.5.

The water content is proportional to the infrared transmittance coefficient (X) represented by the following formula.
X = (log (a / b)) / t
a: transmittance of 3840cm ^-1 (%)
b: Transmittance (%) of the minimum point near 3560 cm ⁻¹
t: Sample measurement thickness (mm)

  However, depending on the shape of the outer container, it may be difficult to directly measure the infrared transmittance coefficient. For example, in the case of a tube shape, it is difficult to directly measure the infrared transmittance. In such a case, an outer container placed on a platinum plate is placed in an electric furnace set to a temperature at which the viscosity (dPa · s) of the glass to be measured is 5.0 ± 0.5 in log display for 5 minutes. Then, after melting and mirror-polishing the obtained massive glass so as to have a thickness of 1 mm, it may be subjected to evaluation. If the measurement sample is prepared under these conditions, the decrease in the amount of water accompanying sample preparation can be minimized, and the obtained infrared transmittance coefficient X can be regarded as the coefficient X before sample preparation.

  The amount of water in the glass is usually adjusted by the amount of water in the combustion gas when the glass is melted and the glass raw material (mixing ratio of boric acid and anhydrous borax). Moreover, when it cannot adjust with these, it can adjust by the dry air bubbling etc. at the time of glass melting.

  The outer casing used for the external electrode fluorescent lamp is required to satisfy the characteristics (1) and (2) above.

(3) Do not contain bubbles.
When bubbles are present in the outer casing which is a dielectric portion, electric charges are accumulated on the electrode side of the bubbles. This causes a minute discharge phenomenon called a tree, and there is a possibility that the glass is melted due to significant local heating. As a result, the airtightness of the outer casing is impaired, and the light emission of the lamp may stop. Therefore, the outer electrode fluorescent lamp envelope is required to have less bubbles than the conventional fluorescent lamp envelope.

  In the case of the envelope of a conventional fluorescent lamp, the number of bubbles has been allowed up to 200 pieces / 100 g in the glass. However, in the envelope of an external electrode fluorescent lamp used for illumination of a liquid crystal display element. It is necessary to be 10 pieces / 100 g or less, more preferably 1 piece / 100 g or less.

(4) Excellent in ultraviolet shielding properties.
In a backlight unit of a liquid crystal display device, since an organic member such as a reflector is provided in the vicinity of a fluorescent lamp, the amount of light may be attenuated due to deterioration of organic substances due to ultraviolet rays. For this reason, the outer casing must be made of glass having a high ultraviolet shielding property so that ultraviolet rays generated inside the fluorescent lamp are not leaked to the outside.

(5) Excellent solarization resistance.
When ultraviolet rays hit the glass, glass coloring called solarization occurs. However, if the glass constituting the outer casing is colored, the amount of light from the lamp decreases, which is not preferable. For this reason, it is necessary to employ glass that is less prone to solarization.

(6) Difficult to bend.
The tube-shaped fluorescent lamp used in the backlight unit is thin and long, and when fixed at both ends, the central part tends to hang down due to the weight of the lamp. However, bending of the lamp is not preferable because it causes interference of the backlight. Further, the flat fluorescent lamp used in the backlight unit is thin and flat, and the central portion is easily bent. However, when this type of lamp bends, the volume of the discharge space changes, causing variations in light emission. Therefore, it is desirable to make an outer container with glass having a density as low as possible and a high Young's modulus.

As a material for the outer container, a usable glass may be appropriately selected in consideration of the various conditions described above. For example, in mass percentage
SiO ₂ 35~75%,
B ₂ O ₃ 0-25%,
Al ₂ O ₃ 0.1-20%,
Li ₂ O + Na ₂ O + K ₂ O 0-25%
A glass having a composition of
SiO ₂ 35~75%,
B ₂ O ₃ 0-25%,
Al ₂ O ₃ 0.1-20%,
Li ₂ O 0-10%,
Na ₂ O 0~18%,
K ₂ O 0-18%,
Li ₂ O + Na ₂ O + K ₂ O 0-25%,
MgO 0-20%,
CaO 0-20%,
SrO 0-30%,
BaO 0-30%,
MgO + CaO + SrO + BaO 1-45%,
ZnO 0-25%,
TiO ₂ 0-15%,
WO ₃ 0~15%,
CeO ₂ 0-5%,
TiO ₂ + WO ₃ + CeO ₂ + Fe ₂ O ₃ 0.005-15%,
ZrO ₂ 0-9%,
SnO ₂ 0-10%,
Nb ₂ O ₅ 0-15%,
Ta ₂ O ₅ 0-15%,
Fe ₂ O ₃ 0-1%
P ₂ O ₅ 0~10%,
Bi ₂ O ₃ 0-30%,
Cl ₂ 0-0.5%,
Sb ₂ O ₃ 0 to 1%
The containing glass can be used. The reason for limiting the range of each component in the above composition will be described below.

SiO ₂ is a main component necessary for constituting the glass skeleton, and the chemical durability improves as the content increases. On the other hand, since there exists a tendency to raise a viscosity, when too much, it will become difficult to obtain long glass. Its content is 35% or more, preferably 40% or more. Moreover, it is 75% or less, Preferably it is 70% or less, More preferably, it is 65% or less, More preferably, it is 59% or less. If SiO ₂ is 40% or more, a usable chemical durability can be secured. If it is 35% or more, the chemical durability is sufficiently high, and the occurrence of burns on the glass surface can be prevented, and a fluorescent lamp with no reduction in luminance over a long period can be produced. If SiO ₂ is 75% or less, it does not take a long time to melt the silica raw material, so that productivity is not hindered. If it is 70% or less, the glass viscosity becomes low. If it is 65% or less, it becomes easy to obtain a viscosity suitable for molding. In particular, if it is 59% or less, the viscosity of the glass is further lowered, and a glass with good dimensional accuracy can be easily obtained.

Although B ₂ O ₃ is not essential, it is a necessary component for improving the meltability and lowering the viscosity, and the glass becomes lower in viscosity as the content increases. If B ₂ O ₃ is contained in an amount of 0.1% or more, the above-described effects appear. On the other hand, there is a tendency to lower the chemical durability and lower the dielectric constant. The upper limit of B ₂ O ₃ is 25% or less, particularly 16% or less, and further 5% or less. If B ₂ O ₃ is 25% or less, chemical durability that can be used practically can be secured. If it is 20% or less, the chemical durability is further improved. If it is 16% or less, there is almost no risk of burns or the like on the glass surface, and a fluorescent lamp that does not decrease in luminance over a long period of time can be produced.

Al ₂ O ₃ is an essential component that greatly improves the stability of the glass, and facilitates melting and forming of the glass. At the same time, it is a component that increases the Young's modulus. On the other hand, since there exists a tendency to raise a viscosity, when too much, it will become difficult to obtain long glass. The content is preferably 0.1% or more, particularly 3% or more, and more preferably 5% or more. Further, it is 20% or less, particularly 15% or less, and further 12.5% or less. If Al ₂ O ₃ is 0.1% or more, the above-described effects appear, and if it is 3% or more, the effect of stabilizing the glass appears. If it is 5% or more, the generation of crystals is reduced, and it is suitable for producing a tube glass having excellent dimensional accuracy. From the viewpoint of obtaining a glass having a high Young's modulus, it is preferably contained in an amount of 6% or more. If Al ₂ O ₃ is 20% or less, the viscosity of the glass melt will not be too high. If it is 15% or less, it becomes easy to achieve both low viscosity and glass stability. If it is 12.5% or less, it becomes possible to achieve both the viscosity suitable for molding and the stability of the glass even if the alkali content is less than 0.1%.

Li ₂ O is an alkali metal oxide, Na ₂ O and K ₂ O acts as a flux to facilitate melting of the glass raw material, to facilitate glass melting. When the total amount of these components is 0.1% or more, an effect of improving the solubility of the glass can be expected. Further, the viscosity of the glass can be lowered to increase the viscosity characteristics, and the stability of the glass can be improved. Furthermore, there is an effect that the electric resistance of the glass is lowered to facilitate the electric melting. However, since it is also a component that increases the dielectric loss tangent of glass, it is necessary to pay close attention when determining the content. When it is desired to reduce the viscosity with an alkali metal oxide, the total amount is preferably 0 to 25%, particularly 1 to 20%, more preferably 8 to 18%. If the total amount of these components is 0.1% or more, it is possible to improve the viscosity characteristics of the glass, and if it contains 4% or more, the effect of reducing the viscosity of the glass is sufficiently obtained. Moreover, since meltability improves, it is preferable also from the point of energy efficiency. If the content is 8% or more, the electric resistance of the glass becomes a value suitable for electric melting. Further, when the alkali component is 25% or less, the dielectric loss tangent is not so high, and the heat generation of the glass can be suppressed to a level causing no practical problem, but if possible, 18% or less is recommended.

The Li ₂ O, Na ₂ O, and the content of each of K ₂ O is respectively Li ₂ O 0~10% (particularly _{0~6%), Na 2 O 0~18} % ( particularly 0.1-10 %, further 1-9% is), K ₂ O 0 to 18% (particularly 0-10, and more preferably from 0.1% to 10%). Note that K ₂ O is recommended to be used preferentially because the degree of increasing the dielectric loss tangent is smaller than that of other alkali components. When Na ₂ O is used, it is particularly preferable to use it together with alkaline earth.

The alkaline earth components MgO, CaO, SrO, and BaO stabilize the glass and prevent the formation of crystals in the glass. In addition, there is an effect of suppressing an increase in dielectric loss tangent by suppressing alkali movement in the glass. On the other hand, there is a possibility that an alkaline earth feldspar crystal is generated by reacting with a refractory or the like of a glass forming apparatus. The total content is 1 to 45%, preferably 5 to 35%, more preferably 10 to 25%. If the content is 3% or more, the effect of preventing alkali migration appears. If the content is 5% or more, the effect of suppressing crystals becomes remarkable. If it is 10% or more, the amount of SiO ₂ can be relatively reduced, and as a result, the viscosity of the glass can be reduced. Further, if it is 45% or less, it is possible to suppress the formation of alkaline earth feldspar crystals, but if it is 35% or less, particularly 25% or less, alkaline earth feldspar crystals are very difficult to form, and there are restrictions on molding equipment and the like Less. In order to reduce the density of the glass, for example, SrO or CaO may be used rather than BaO.

  MgO has the effect of increasing the Young's modulus of glass in addition to the above characteristics, but depending on the combination with other components, Mg-based crystals are easily generated. The content is 0 to 20%, preferably 0 to 5%, more preferably 0 to 2.5%. If it is 20% or less, precipitation of Mg-based crystals can be suppressed, and if it is 5% or less, Mg-based crystals are difficult to precipitate during glass forming. If it is 2.5% or less, Mg-based crystals are very difficult to precipitate, which is preferable because the degree of freedom in combination with other components increases.

  CaO is a component similar to MgO, but is less reactive with refractories than MgO. The content is 0 to 20%, preferably 0.1 to 10%, more preferably 1 to 8%, and further preferably 1 to 5%. When CaO is contained in an amount of 0.1% or more, the effect of stabilizing the glass appears, and when it is contained in an amount of 1% or more, the glass is further stabilized. Moreover, if it is 20% or less, precipitation of Ca type | system | group crystal | crystallization can be suppressed and it will become easy to obtain a tube glass with high roundness. If it is 10% or less, particularly 8% or less, Ca-based crystals are very difficult to precipitate. More preferably, it is 5%.

The SrO content is 0 to 30%, preferably 0.1 to 25%, more preferably 3 to 20%, more preferably 5 to 15%. If SrO is contained in an amount of 0.1% or more, an effect of stabilizing the glass appears. More effectively, it is 3% or more, and if it is 5% or more, the amount of SiO ₂ can be relatively reduced, and as a result, the viscosity of the glass can be reduced. Moreover, if it is 30% or less, precipitation of Sr-type crystal | crystallization can be suppressed and it will become easy to obtain the tube glass excellent in roundness. If it is 25% or less, particularly 15% or less, Sr-based crystals are more difficult to precipitate.

The BaO content is 0 to 30%, preferably 3 to 30%, more preferably 5 to 15%. In the case of containing BaO, when glass touches a refractory rich in SiO ₂ and Al ₂ O ₃ , Ba feldspar crystals are likely to be generated at that portion. For this reason, it is better that the amount of BaO in the glass is as small as possible depending on the molding equipment used. However, BaO is preferably contained in an amount of 3% or more because it has a great effect of stabilizing glass and suppressing crystal precipitation. If there is no restriction on the forming equipment, if it exceeds 5%, the amount of SiO ₂ can be relatively reduced, and as a result, the viscosity of the glass can be reduced. Moreover, if it is 30% or less, precipitation of Ba type | system | group crystal | crystallization can be suppressed and the tube glass of the outstanding roundness will be obtained, and if it is 15% or less, Ba type crystal | crystallization will be hard to generate | occur | produce further.

  ZnO is a component that has the effect of reducing the viscosity of the glass and suppressing crystal precipitation. Its content is 0-25%, preferably 0-5%. If it is 25% or less, crystals containing Zn are hardly formed, and if it is 5% or less, volatilization is reduced, which is more preferable.

TiO ₂ , CeO ₂ , Fe ₂ O ₃ and WO ₃ are optional components. However, when it is desired to shield ultraviolet rays, it is desirable to contain one or more kinds, in which case the total amount is 0.005 to 15%, In particular, it is preferably 0.005 to 10%, more preferably 0.1 to 3%. The above effect can be confirmed if it is 0.005% or more, but it is desirable to contain 0.1% or more in order to surely obtain the above effect. Moreover, if it is 10% or less, it can produce stably, without a crystal | crystallization precipitating in glass.

TiO ₂ has the highest solarization prevention and ultraviolet shielding effect. It is also a component that increases the dielectric constant and Young's modulus of glass. When it is desired to obtain the above effect, it is preferable to contain 0.01% or more, particularly 0.1% or more. When the content is 0.1% or more, the above-described effects can be obtained without being affected by coloring such as Ce. However, TiO ₂ may cause crystals in the glass, or if it coexists with Fe ₂ O _{3 in the} glass. Therefore, the upper limit of TiO ₂ is preferably 15% or less, particularly 5% or less. If it is 15% or less, it can be stably produced without producing crystals in the glass, and if it is 5% or less, the effect of coloring is reduced even if the content of Fe ₂ O ₃ is increased.

WO ₃ has an effect of shielding ultraviolet rays. Its content is 0-15%, preferably 0-5%. If it is less than 15%, it can be stably produced without precipitating crystals in the glass.

The CeO ₂ content is preferably 5% or less. CeO ₂ has an ultraviolet shielding effect and a solarization prevention effect. There is also a clarification action. When it is desired to obtain the above effect, it is preferably 0.01 to 5%, particularly preferably 0.1 to 3%. If it is 5% or less, it is possible to melt the glass without precipitating crystals. On the other hand, if it is 0.01% or more, the effect as a clarifying agent can be expected, if it is 0.1% or more, the effect of preventing solarization can be expected, and if it is more than 2%, a high ultraviolet shielding effect can be obtained. It becomes possible to shield ultraviolet rays around 313 nm alone with a glass wall thickness of 0.2 mm.

ZrO ₂ has an effect of improving the chemical stability of the glass and preventing the glass from being blown with alkali or alkaline earth. It is also a component that increases Young's modulus. When it is desired to obtain the above effect, it is preferable to contain 0.01% or more. On the other hand, ZrO ₂ is a component that increases the glass viscosity. For this reason, it is desired to be 9% or less, particularly 5% or less, further 3% or less, and optimally 2%. In particular, if ZrO ₂ is 3% or less, a stable glass can be easily obtained without producing crystals containing Zr, and if it is 2% or less, there is no fear of inducing precipitation of other crystals.

SnO ₂ has a clarification action and an effect of stabilizing the glass. If SnO2 is 0.01% or more, a clarification effect can be expected. On the other hand, SnO ₂ is a component that may cause crystals to precipitate in the glass. Therefore, it is preferably 10%, particularly 5% or less. If SnO ₂ is 10% or less, particularly 5% or less, it is preferable that no crystals are formed.

Nb ₂ O ₅ has an effect of preventing solarization, and its content is 0 to 15%, preferably 0 to 10%. If it is 15% or less, it can be stably produced without precipitating crystals, and if it is 10% or less, the process can be further stabilized.

Ta ₂ O ₅ has an effect of preventing solarization, and its content is 0 to 15%. If it is 15% or less, it can be stably produced without precipitating crystals.

P ₂ O ₅ is an element that becomes a skeletal component of glass, and has an effect of suppressing generation of crystals in a small amount. When it is desired to obtain the above effect, it is preferable to contain 0.1% or more. On the other hand, if there is too much P ₂ O _5, phase separation occurs and the glass becomes cloudy. Therefore, the content of P ₂ O ₅ is desirably 10% or less, particularly 5% or less, and further desirably 3% or less. If it is 10% or less, the phase separation is reduced, and if it is 5% or less, it is preferable for mass production, and if it is 3% or less, it is more preferable.

Bi ₂ O ₃ is a component that increases the dielectric constant of the glass, and is preferably contained when a high dielectric constant is required to reduce the area of the external electrode. The content is preferably 0 to 30%. If it is less than 30%, it can be stably produced without precipitating crystals in the glass.

  Chloride is effective as a fining agent and can be introduced into the glass by using a chloride source, such as barium chloride. It tends to volatilize before the molding of the glass, and its residual content is 1% or less, particularly 0.5 or less. In order to obtain an effect as a fining agent, the residual content may be 0.0001% or more, particularly 0.001% or more.

Sb ₂ O ₃ is effective as a fining agent. In order to acquire the said effect, it is preferable that it is 0.01% or more, especially 0.1% or more. If it is 0.01% or more, a clarification effect appears, and if it is 0.1% or more, a sufficient clarification effect can be obtained. On the other hand, when Sb ₂ O ₃ increases, a phenomenon may occur in which Sb is reduced by heating during lamp processing and the glass becomes black. Therefore, Sb ₂ O ₃ is preferably limited to 1% or less.

In addition to the above components, various components may be included. For example, Fe ₂ O ₃ , sulfur component (SO ₃ ), F ₂ , and rare earths (other than CeO ₂ ) may be contained in the glass.

Fe ₂ O ₃ is a component inevitably contained in the glass industry unless it is intentionally excluded, and it is 1% or less. Depending on the valence and coordination number of Fe ₂ O ₃ , the glass may be colored or solarized, or it may absorb ultraviolet rays to suppress solarization. That is, Fe ²⁺ ions give the glass a blue color, and in the case of low coordination of Fe ³⁺ ions, the glass turns brown. Further, in the case of high coordination of Fe ³⁺ ions, it has a sharp absorption in the ultraviolet region, and imparts ultraviolet absorptivity without coloring the glass. It also has an effect of preventing solarization. Each ion coexists, and the ratio of each ion changes continuously according to the degree of oxidation of the glass. Therefore, it is necessary to make the oxidation state so that the trivalence of Fe is as much as possible, but it is difficult to make only the trivalent high coordination of Fe completely. For this reason, management of content of Fe itself becomes important. The content of Fe ₂ O ₃ is preferably 0.001 to 0.1%, preferably 0.005 to 0.06%, and more preferably 0.01 to 0.03%. In order to obtain the effect of preventing solarization, 0.001% or more is desirable, and 0.005% or more is recommended. When the content is 0.01% or more, the effect of preventing solarization is further enhanced. Moreover, if it is 0.1% or less, it becomes possible to eliminate the influence of coloring caused by Fe ions, but it is desirable that it is 0.06% or less. In the case of containing TiO ₂ , coloring is promoted, so that it is preferably 0.03% or less particularly in applications such as a high-definition liquid crystal TV having a severe color tone.

The sulfur component in the glass raw material is a component that facilitates the dissolution of the raw material powder and improves the bubble breakage. When it is desired to obtain the above effect, it is preferable to contain 0.0001% or more, particularly 0.0005% or more, expressed as SO ₃ . However, if the sulfur component remains excessively in the glass, it may be reboiled during lamp processing and cause bubbles, so its content is 0.5% or less, especially 0.2% or less, and further 0.1% Should be restricted to:

Note that SO ₃ may be contained as an impurity in the raw material and fuel, and depending on the amount of the impurity, it is necessary to select the raw material. If the impurities alone are insufficient, they can be added in the form of sulfate. Since the allowable amount of SO ₃ increases as the alkali increases, the content of SO ₃ may be adjusted in consideration of the state of glass bubbles. Further, as a method for reducing SO ₃ remaining in the glass, a method of coexisting with at least one kind of CeO ₂ , SnO ₂ , Sb ₂ O ₃ , Cl, F and nitrate, preferably two or more kinds, There is a method of bubbling with a gas such as air.

F ₂ has a clarification effect and can be introduced into the glass by using a fluoride raw material, such as aluminum fluoride. It tends to volatilize before the molding of the glass, and its residual content is preferably 1% or less.

Rare earths such as Y ₂ O ₃ and La ₂ O ₃ can be contained up to 10% for the purpose of increasing the Young's modulus of the glass.

As ₂ O ₃ has a large refining action and has an effect of suppressing coloring due to high coordination of Fe ³⁺ ions. However, coexistence with CeO ₂ causes solarization. Further, since it is highly toxic, it is desirable not to introduce it in the design, and it is desirable to limit the impurity level to 0.1% or less, preferably 0.005% or less. PbO is also desired to have an impurity level of 0.5% or less, preferably 0.1% or less, and more preferably 0.01% or less, for environmental reasons like As ₂ O ₃ .

  Next, a method for manufacturing the outer electrode fluorescent lamp outer casing of the present invention will be described.

  First, the case of manufacturing a tubular envelope will be described.

  The raw materials are prepared so as to have the above characteristics or composition, mixed, and then melted in a melting furnace. At this time, the amount of water in the glass is adjusted as necessary. Next, the molten glass is formed into a tubular shape by using a tube drawing method such as the Danner method, the down draw method, or the up draw method. Thereafter, the outer glass fluorescent lamp envelope can be obtained by cutting the tubular glass into a predetermined size and post-processing as necessary.

  The dimensions of the outer electrode fluorescent lamp outer tube are not particularly limited, but when used in a backlight unit of a liquid crystal display device, the outer diameter is 8 mm or less, particularly 5.2 mm or less. It is desirable to be. Further, the thickness of the outer tube is desirably thin in order to increase the capacitance, and specifically, 0.6 mm or less, particularly 0.4 mm or less, and further 0.3 mm or less. Further, the variation in thickness affects the power supplied to the lamp and causes unevenness in the brightness of each lamp. Therefore, it is important to make the variation as small as possible, and it is desirable that the variation is within 0.02 mm, particularly 0.01 mm or less. In addition, the thickness variation was determined by measuring the thickness of the outer peripheral portion of the outer container portion with a micro gauge, and determining the difference between the maximum value and the minimum value.

  Next, a method for producing a flat outer jacket will be described.

  The raw materials are prepared so as to have the above characteristics or composition, mixed, and then melted in a melting furnace. At this time, the amount of water in the glass is adjusted as necessary. Next, the molten glass is formed into a sheet by a method such as an overflow method, a float method, or a slot down method. Thereafter, the plate-like glass is cut into a predetermined size and post-processed as necessary to obtain a back plate. Further, a plate glass produced in the same manner is re-formed by pressing or the like, and a plurality of concave portions are formed so that a discharge space can be formed. In this way, a front plate is obtained. Thereafter, the front plate and the back plate are sealed using a sealing material or the like. In addition, you may apply | coat a fluorescent substance to the predetermined location of a front plate and a back plate beforehand. In this way, a flat outer electrode fluorescent lamp envelope having a plurality of discharge spaces can be obtained.

  The outer electrode fluorescent lamp can be produced according to a conventional method using the outer container thus obtained. Prior to assembling the fluorescent lamp, electrodes can be formed on the outer surface of the outer casing, for example, in the vicinity of both ends of a tube-shaped outer casing, or on the back plate of a flat outer casing.

  Hereinafter, the present invention will be described based on examples. Table 1 shows Examples (Sample Nos. 1 to 3) and Comparative Example (No. 4) of the glass constituting the outer container of the present invention.

  First, glass raw materials were prepared so as to have the composition shown in the table, and then melted at 1600 ° C. for 18 hours using a platinum crucible. After melting, the melt was shaped into a predetermined shape and processed to prepare each glass sample. The characteristics of each sample are shown in the table. The main raw materials are silicon oxide (1% or less on a 150 μm sieve, 30% or less under a 45 μm sieve), aluminum oxide (average particle size 50 μm / microtrack), boric acid (10% or less on a 400 μm sieve, 10% or less on a 63 μm sieve) , High purity calcium carbonate, strontium carbonate (average particle size 2 μm), barium nitrate (1% or less on a 500 μm sieve, 5% or less under a 45 μm sieve), barium carbonate (average particle size 2 μm), lithium carbonate (granulated product), Uses sodium carbonate (granulated product), potassium carbonate, zinc oxide (1% or less on 45 μm sieve), and reagent grade boric acid, magnesium oxide, strontium nitrate, barium chloride, zirconium oxide, antimony pentoxide as other minor components , Aluminum metaphosphate, titanium oxide, iron oxide, tungsten oxide, strontium sulfate, and cerium oxide It was used.

  About the dielectric constant and dielectric loss tangent in 1 MHz, the plate-shaped sample of the magnitude | size of 50x50x3tmm was produced from each glass sample, the 30 mm diameter electrode was affixed, and it measured with the LCR meter. The measurement conditions were 1 MHz and 25 ° C.

  Evaluation of dielectric constant and dielectric loss tangent at 40 KHz was performed as follows. Specifically, first, as shown in FIG. 1, a # 1000-finished disk-shaped sample G having a diameter of 20 mm and a thickness of 1 mm is prepared, and a main electrode a having an outer diameter of 14.5 mm and a main electrode a are provided on one side thereof. A guide electrode b having an outer diameter of 20 mm and an inner diameter of 16 mm provided concentrically on the outer side of each was prepared by gold vapor deposition. On the other surface of the sample, a counter electrode c was formed on the entire surface by gold vapor deposition.

  As shown in FIG. 2, the measuring apparatus has a structure including a heater 100, a sample measuring chamber 110, and an LCR meter (not shown). The heater is a non-dielectric wound tape heater. The sample measurement chamber 110 is installed in a shield (metal cylinder) 120 in order to avoid electromagnetic induction due to the influence of the heater 100. In the sample measuring chamber 110, a main electrode terminal 111 and a guard electrode terminal 112 for contacting the main electrode a and the guard electrode b of the sample G are provided so as to be integrally movable up and down. The main electrode terminal 111 is connected to the terminal of the LCR meter, and the guard electrode terminal 112 is connected to the guard terminal of the LCR meter via the lead wires. In addition, a counter electrode terminal 113 for contacting the counter electrode c of the sample G is provided in the upper part of the sample measuring chamber 110. The counter electrode terminal 113 is connected to the terminal of the LCR meter via a conducting wire. In addition, a shield (aluminum foil, not shown) is provided between the conductive wire of the counter electrode terminal 113 and the conductive wire of the main electrode terminal 111 so as not to be affected. A thermocouple 114 connected to a thermometer is installed in the vicinity of the sample G held in the sample measurement chamber 110 so that the sample temperature can be measured.

  In order to measure the dielectric characteristics of the sample G using the measuring apparatus, first, the sample G is placed on the main electrode terminal 111 and the guard electrode terminal 112. Next, both terminals are moved upward, and the sample G is held in a state of being pressed against the counter electrode terminal 113 installed at the upper part. Subsequently, the sample G is heated by the heater 100, and the dielectric characteristics when the temperature reaches a predetermined temperature are measured by an LCR meter. Thus, the dielectric loss tangent was measured under conditions of room temperature-1 MHz, 40 KHz-150 ° C., 40 KHz-250 ° C., 40 KHz-350 ° C.

  The thermal expansion coefficient was measured with a thermal expansion measuring device.

  The temperature corresponding to each viscosity was determined by ASTM C336, ASTM C338 and the ball pulling method.

  The liquid phase viscosity was determined as follows. First, glass crushed to a particle size of about 0.1 mm was placed in a boat-shaped platinum container, held in a temperature gradient furnace for 24 hours, and then taken out. The sample is observed with a microscope to measure the temperature at which the initial phase of the crystal appears (liquidus temperature), and then the viscosity corresponding to the temperature of the initial phase is determined from the relationship between the temperature and viscosity of the glass measured in advance. (Liquidus viscosity) was determined.

  The coefficient X indicating the amount of water was obtained by substituting the transmittance a at the minimum point near 3846 cm −1 and the transmittance b at the minimum point near 3560 cm −1 measured with an infrared spectrophotometer into the following equation. . Here, t is the sample thickness (mm).

X = (log (a / b)) / t
The density was determined by the Archimedes method, and the Young's modulus was determined by the bending resonance method.

  Next, the obtained glass sample was evaluated for ultraviolet shielding property, solarization resistance, bubble number, reboil property, workability, and coloration. The results are shown in Table 2.

  The ultraviolet shielding property was determined as “A” when a plate glass sample having a thickness of 0.2 mm having both surfaces mirror-polished was prepared and the spectral transmittance at a wavelength of 253.7 nm was measured. The wavelength of 253.7 nm is a mercury emission line. For applications of the present invention, the lower the transmittance at this wavelength, the better.

  The ultraviolet solarization resistance was evaluated as follows. First, a sample was obtained by mirror polishing both surfaces of a 1 mm thick plate glass. Next, the wavelength of light at which the transmittance of the sample before ultraviolet irradiation showed 80% was measured. Further, after the sample was irradiated with ultraviolet light having a main wavelength of 253.7 nm for 60 minutes at an irradiation distance of 20 mm by a 40 W low-pressure mercury lamp, the transmittance was compared with the transmittance after irradiation before the irradiation of 400 nm. % Or less was designated as “A”. In addition, although the transmittance | permeability fall becomes so large that it is inferior to ultraviolet solarization resistance, it is important that the outer casing for fluorescent lamps, such as a liquid crystal backlight, hardly has this fall.

  For the coloring of the glass, a glass sample having a thickness of 1 mm was observed with the naked eye, and a glass sample without coloring was designated as “A”.

  The solubility was evaluated as follows. First, 100 g of a glass raw material was put into a triangular crucible, heated at 1550 ° C. for 2 hours, and then cooled and solidified in the crucible. After solidification, the glass lump was taken out from the crucible so as not to be broken and annealed. Then, the central part of the glass lump was cut out with a thickness of 7 mm, and the cross section was observed using transmitted light. As a result, “A” indicates that no undissolved material is found, “B” indicates that it is slightly recognized, and “C” indicates that the undissolved material aggregates and appears white.

  The number of bubbles is a value obtained by observing a glass sample cut out in a block shape, counting the number of bubbles (bubbles having a diameter of about 30 μm or more) that can be seen with a 40 × microscope, and converting the number to 100 g.

  Workability was evaluated by sealing the end of the tube glass. Specifically, it was performed as follows. First, the sample is processed into a glass tube, and while one end is heated with a burner, the encapsulated surface is picked and sealed with a scissor-like tool to confirm that there is no reboil bubbles and no deformation around the encapsulated tube. If there was no problem, “A” was assigned.

  For the coloring of the glass, a glass sample having a thickness of 1 mm was observed with the naked eye, and a glass sample without coloring was designated as “A”.

  The mold adhesion was evaluated by evaluating the ease of peeling from the mold when a plate glass was sandwiched between the molds and heated to a softening point of + 30 ° C., and the mold that could be released without problems was designated as “A”. .

  Using a glass having the same composition as that of the glass sample used in Example 1, a tube-type outer electrode outer tube for fluorescent lamp was produced, and the variation in thickness was evaluated. As a result, it was confirmed that the thickness variation was within 0.01 mm.

  The outer container was produced as follows. First, after the raw materials prepared so as to be the same glass as each sample were melted in a refractory kiln at 1600 ° C. for 24 hours, the glass melt was supplied to a dunner forming apparatus, piped, and cut. A tube glass having a diameter of 3.0 mm, a wall thickness of 0.3 mm, and a length of 800 mm was obtained and used as an outer container.

The thickness variation was evaluated by measuring the roundness with an outer diameter inner diameter measuring instrument.
The swell of the plate glass was measured using a surface roughness meter.

  An external electrode fluorescent lamp is produced using the mantle container produced in Example 2. Here, two types of lamps are manufactured.

  A method for manufacturing the fluorescent lamp of the first embodiment will be described. The fluorescent lamp of the first form has a structure in which a sealing member and an exhaust pipe are respectively joined to both opening ends of an outer casing in which electrodes are previously formed on the outer peripheral surface using sealing glass. In this embodiment using the sealing glass, the sealing glass functions as a thermal fuse, which is safe. That is, since the sealing glass is not high in heat resistance, the temperature of the outer casing should be the heat resistance temperature of the sealing glass, that is, in the case of amorphous glass, the softening point (for example, 390 ° C. in LS-1301 described later), the crystallinity In the case of glass, when the melting temperature of the precipitated crystal is exceeded, the sealing glass is softened to break the airtightness of the lamp, and the lamp can be stopped to prevent a peripheral member from being fired.

  First, as shown in FIG. 3A, the sealing member 1, the sealing glass tablet 2, the outer container 4 on which the electrode 3 is formed, and the exhaust pipe 5 are inserted and disposed in the carbon mold 10 as shown in FIG. Baking is performed at the sealing temperature of the sealing glass, and the members are joined and integrated. A phosphor 6 is applied in advance in the transparent tube glass 4 constituting the outer container 4.

  The electrode 3 formed in advance on the outer casing 4 is made of a material such as Ni, Cu, or Ag. Although there is no restriction | limiting in particular in an electrode formation material, For example, DD3600Cu paste, DD300Ag paste, DD7000Ni paste, etc. by Kyoto Elex Co., Ltd. can be used. For example, when DD300Ag paste is used, a homogeneous electrode layer adhered to the outer surface can be obtained by transfer printing on the outer peripheral surface of the outer container and sintering in nitrogen at 600 ° C. As an electrode, there is a method in which an aluminum foil is bonded with an adhesive.

  The sealing glass tablet 2 includes, for example, LS-1301 (using amorphous glass, sealing temperature 430 ° C., heat-resistant temperature 390 ° C.), LS-1320 (using amorphous glass, sealing) manufactured by Nippon Electric Glass Co., Ltd. 320 ° C, heat resistance 270 ° C), LS-0206 (using amorphous glass, sealing temperature 450 ° C, heat resistance 410 ° C), LS-7105 (using crystalline glass, sealing temperature 450 ° C, heat resistance) 500 degreeC) etc. can be used. These tablets are formed by extruding a glass powder kneaded with a low-temperature decomposable binder, and sealing each member without affecting the electrodes on the phosphor or dielectric member. it can. In the above example, the sealing glass is all lead-based glass, but silver phosphate glass, tin phosphate glass, or the like may be employed. In selecting the sealing glass, the sealing glass may be appropriately selected in consideration of the heat resistant temperature and the thermal expansion coefficient of the sealing member such as the outer container.

  Further, the sealing member 1 is formed by pressing the outer container glass with an alumina ball mill, classifying it with a sieve having an opening of 200 μm, adding a binder to the glass powder, granulating it, and then press-molding it into a disk shape. Sintered. The shape of the sealing member is not limited to a disk shape, and may be a convex shape, for example.

  Next, as shown in FIG. 3B, a mercury amalgam boat 7 is inserted into the exhaust pipe 5, and after exhausting by the exhaust device 11, Ar and Ne gas are introduced.

Subsequently, the end of the exhaust pipe 5 is sealed, and the mercury amalgam boat 7 is further heated to introduce Hg into the pipe. (Fig. 3 (c))
Thereafter, the exhaust pipe 5 is sealed off to obtain a fluorescent lamp of the first form as shown in FIG.

  It is also possible to adopt a form in which either one of the sealing member and the exhaust pipe is bonded by a sealing glass tablet and the other is directly fused to the outer container.

  A method of manufacturing the fluorescent lamp of the second form will be described. The fluorescent lamp of the second form has a structure in which the sealing member and the exhaust pipe are not joined.

  First, as shown in FIG. 4A, the phosphor 6 is applied inside the outer container 4. At that time, excess phosphor is removed with a brush. Further, a metal paste for electrode formation is applied to the outer peripheral portion of the outer container 4. Thereafter, the entire tube is baked at 600 ° C., and the phosphor 6 and the electrode 3 are baked simultaneously. The formation of the electrode 3 can also be performed in the final process.

Subsequently, as shown in FIG. 4B, one end of the outer container is melt-sealed, and then the other end is evacuated, Ar and Ne gas sealed, and Hg introduced into the tube. (Fig. 4 (c) (d))
Thereafter, the portion of the outer container where the mercury amalgam boat 7 is present is cut off to obtain a fluorescent lamp of the second form. (Fig. 4 (e))
In the fluorescent lamp of the second form, when the outer container is made of glass having insufficient heat resistance, a metal paste material that can be baked at about 500 ° C. is used, or an electrode may be attached in the final process. Is possible.

  In addition to the first and second forms, it is also possible to adopt a form in which a sealing member or an exhaust pipe is joined to one end of the outer container and the other end is melt-sealed.

  A flat outer electrode fluorescent lamp envelope (FIG. 6) was prepared using glass having the same composition as the glass sample used in Example 1, and the undulation and thickness variation of the back plate on which the electrodes were formed were evaluated. As a result, it was confirmed that the swell was within 0.01 mm. Moreover, when the thickness variation was evaluated with a gauge capable of measuring up to 1/100 mm, it was below the measurement limit.

  The outer container was produced as follows. First, after the raw materials prepared so as to be the same glass as each sample were melted at 1600 ° C. in a refractory kiln, the glass melt was supplied to a float forming apparatus, and was drawn and cut to 300 × 200 mm A plate glass having a thickness of 0.9 mm was obtained, and this was used as a back plate 41 for an outer container. Similarly, a plate glass having a size of 300 × 200 mm and a thickness of 0.9 mm was pressed by a mold to form a recess 421 for forming a discharge space. In this way, a front plate 42 for a mantle container was obtained. Subsequently, the front plate 42 and the back plate 41 were sealed with a sealing material to produce an outer container.

  In order to produce an external electrode fluorescent lamp using this mantle, for example, the following method can be employed.

First, an Al ₂ O ₃ protective film (not shown) is formed in the discharge space forming recess 421 of the front plate 42, and the phosphor 6 is applied thereon. In addition, the electrode 3 is formed on the outer surface side of the back plate 41, an Al ₂ O ₃ protective film (not shown) is formed on the inner surface side, and the phosphor 6 is applied thereon. Subsequently, the spacer 8 coated with sealing glass is disposed between the front plate 42 and the rear plate 41, and sealed by heat treatment. Further, the exhaust pipe 5 is disposed in the exhaust hole formed in the back plate 41 via the sealing glass tablet 2 and is heat-bonded. Next, while heating to about 400 ° C. and exhausting from the exhaust pipe 5, cooling is performed and gas is introduced into the pipe. Thereafter, the exhaust pipe 5 is chipped off. When mercury is introduced into the lamp, mercury amalgam is placed in the exhaust pipe and diffused into the lamp.

  In this way, a flat external electrode fluorescent lamp having a plurality of discharge spaces can be produced.

It is explanatory drawing which shows the sample which measures a dielectric property, (a) is the figure which looked at the sample from the side surface, (b) has shown the figure which looked at the sample from the bottom face side. It is explanatory drawing which shows the apparatus which measures a dielectric property. It is explanatory drawing which shows the method of manufacturing the tubular external electrode fluorescent lamp of a 1st form. It is explanatory drawing which shows the method of manufacturing the tube type external electrode fluorescent lamp of a 2nd form. It is explanatory drawing which shows the usage method of a tube type external electrode fluorescent lamp. It is explanatory drawing which shows the method of manufacturing a flat fluorescent lamp. It is explanatory drawing which shows the cross section of a planar fluorescent lamp.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing member 2 Sealing glass tablet 3 Electrode 4 Mantle container 5 Exhaust pipe 6 Phosphor 7 Mercury amalgam boat 8 Spacer 10 Carbon type 11 Exhaust device 20 Power supply 41 Back plate for mantle container 42 Front plate for mantle container 421 Discharge space formation Recess L1, L2 External electrode fluorescent lamp

Claims (15)

An outer electrode fluorescent lamp envelope used for manufacturing an external electrode fluorescent lamp having a structure in which an electrode is provided on an outer surface, and a dielectric loss tangent at 40 KHz and 250 ° C. is 0.02 (excluding 0.02) to An outer electrode fluorescent lamp outer casing made of glass having a 0.2 and a strain point of 650 ° C. or lower. An outer electrode fluorescent lamp envelope for a tube-type external electrode fluorescent lamp according to claim 1, wherein the outer electrode fluorescent lamp envelope is provided with electrodes in the vicinity of both ends of the outer peripheral surface. . 2. A flat outer electrode fluorescent lamp envelope having a plurality of discharge spaces, comprising a front plate for emitting light and a back plate on which electrodes are formed as constituent materials. A jacket for an external electrode fluorescent lamp. 2. The outer electrode fluorescent lamp envelope according to claim 1, wherein the outer electrode fluorescent lamp envelope is made of glass having a dielectric loss tangent of 1 MHz at room temperature of 0.003 or less. 2. The outer electrode fluorescent lamp envelope according to claim 1, wherein the outer electrode fluorescent lamp envelope is made of glass having a dielectric loss tangent at 40 KHz and 150 [deg.] C. of 0.005 (excluding 0.005) to 0.05. 2. The outer electrode fluorescent lamp envelope according to claim 1, wherein the outer electrode fluorescent lamp envelope is made of glass having a dielectric loss tangent at 40 KHz and 350 [deg.] C. of 0.1 (not including 0.1) to 2. 2. The outer electrode fluorescent lamp envelope according to claim 1, wherein the rate of change in dielectric loss tangent between 150 and 250 [deg.] C. is 0.002 or less. The outer electrode fluorescent lamp envelope according to claim 1, wherein the outer electrode fluorescent lamp envelope is made of glass having a temperature corresponding to a viscosity of 10 ⁴ dPa · S of 1200 ° C or lower. The outer electrode fluorescent lamp envelope according to claim 1, wherein the outer electrode fluorescent lamp envelope is made of glass having a temperature corresponding to a viscosity of 10 ³ dPa · S of 1400 ° C or lower. 2. The outer electrode fluorescent lamp envelope according to claim 1, wherein the outer electrode fluorescent lamp is made of glass having a liquidus viscosity higher than 10 ⁴ dPa · S. 2. An outer electrode fluorescent lamp envelope according to claim 1, which is made of glass having an infrared transmittance coefficient (X) represented by the following formula of 0.1 to 0.8.
X = (log (a / b)) / t
a: Transmittance (%) of 3840 cm ⁻¹
b: Transmittance (%) of the minimum point near 3560 cm ⁻¹
t: Sample measurement thickness (mm) In mass percentage,
SiO ₂ 35~75%,
B ₂ O ₃ 0-25%,
Al ₂ O ₃ 0.1-20%,
Li ₂ O 0-10%,
Na ₂ O 0~18%,
K ₂ O 0-18%,
Li ₂ O + Na ₂ O + K ₂ O 0-25%,
MgO 0-20%,
CaO 0-20%,
SrO 0-30%,
BaO 0-30%,
MgO + CaO + SrO + BaO 1-45%,
ZnO 0-25%,
TiO ₂ 0-15%,
WO ₃ 0~15%,
CeO ₂ 0-5%,
TiO ₂ + WO ₃ + CeO ₂ + Fe ₂ O ₃ 0.005-15%,
ZrO ₂ 0-9%,
SnO ₂ 0-10%,
Nb ₂ O ₅ 0-15%,
Ta ₂ O ₅ 0-15%,
Fe ₂ O ₃ 0 to 1%
P ₂ O ₅ 0~10%,
Bi ₂ O ₃ 0-30%,
Cl ₂ 0~0.5%,
Sb ₂ O ₃ 0 to 1%
2. The outer electrode fluorescent lamp envelope according to claim 1, wherein the outer electrode fluorescent lamp envelope is made of glass. The outer electrode fluorescent lamp envelope according to claim 1, wherein an electrode is formed on the outer surface. 3. The outer electrode fluorescent lamp envelope according to claim 2, wherein electrodes are formed in the vicinity of both ends of the outer peripheral surface. 4. The outer electrode fluorescent lamp envelope according to claim 3, wherein an electrode is formed on the back plate.