JP4305844B2 - Tube for fluorescent lamp - Google Patents

Description

  The present invention relates to an outer tube of 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, notebook computers, TV monitors, personal computer (PC) monitors, in-vehicle instruments, etc. that use a dedicated illumination device (hereinafter referred to as backlight unit) for transmissive liquid crystal display elements are generally used. Has been.

  A fluorescent lamp serving as a light source of the backlight unit is a cold cathode tube, but its light emission principle is the same as that of a general illumination fluorescent lamp. That is, the mercury gas enclosed by the discharge between the electrodes is excited, and the phosphor coated on the inner wall surface of the glass tube emits visible light by ultraviolet rays emitted from the excited gas. However, since a cold cathode tube has a high initial voltage, a high voltage and a high frequency are applied by an inverter power supply. In such a fluorescent lamp, a combination of a borosilicate glass and an introduced metal, which has high thermal and mechanical strength and is advantageous in terms of electrical insulation, a fluorescent lamp using Kovar metal sealing glass and Kovar metal, Fluorescent lamps using tungsten metal sealing glass and tungsten metal have been developed and commercialized. The lamp power unit includes an individual capacitor for controlling current and an individual inverter power source. For this reason, a unit in which an inverter power supply and a capacitor are set for each lamp is required.

  A backlight unit that emits a plurality of fluorescent lamps evenly on a back side of a liquid crystal display device at intervals of about 1 to 5 cm and emits light through a diffusion plate is mainly used for a TV monitor.

  In the TV monitor, since the power supply is filled by the number of lamps, not only the volume occupied by the power supply is large in the display device but also the price increases. Therefore, it is expected to combine the power sources of the unit into one, but this has not been possible because the capacitor cannot be omitted.

  The lifetime of a conventional cold cathode lamp is considered to be determined by forming an alloy with Hg and consuming Hg when the metal electrode is sputtered in the lamp. In order to maintain the electron emission characteristics, a metal electrode is necessary, and the lifetime is limited. Its lifetime is not long enough for TV monitors.

For this reason, an external electrode lamp in which there is no internal electrode that tends to affect the life and the electrodes are disposed in the vicinity of both ends of the outer peripheral surface of the lamp has been studied. (Patent Document 1, Non-Patent Document 1)
JP2002-8408 JP 2000-311659 A JP 2002-338296 A Journal of the Illuminating Society of Japan vol. 87 no. 1 2003 p18

  The external electrode lamp does not emit electrons directly from the electrodes, but causes the glass outer tube to function as a dielectric and emits electrons from the inner surface of the tube due to its dielectric properties. That is, a mechanism that replaces the condenser is constructed in the lamp, and as a result, the condenser is not necessary and the power supply can be integrated.

  However, in this structure, the temperature of the glass acting as a dielectric increases, but the volume resistance at high temperatures is not sufficient with the conventional glass envelope material, and not only does the glass generate heat as a resistor, but also increases the dielectric loss tangent. Doing so increases dielectric loss and causes energy loss, which is not preferable from the viewpoint of energy efficiency. Moreover, since the generated energy loss is converted into thermal energy, the temperature of the electrode part rises abnormally and there is a risk of causing a fire in the peripheral members. In particular, the liquid crystal backlight unit is surrounded by a reflector or a liquid crystal panel, so that generated heat is difficult to dissipate and the lamp ambient temperature tends to rise. For this reason, it is necessary to consider the heat dissipation of the lamp, and various restrictions arise, such as the need for a heat dissipation device and the inability to increase the lamp output.

  For these reasons, there is a need for a glass envelope for an external electrode fluorescent lamp that does not increase the energy loss extremely even when the lamp ambient temperature rises, that is, the lamp heat generation does not increase excessively. It was.

  An object of the present invention is to provide an outer electrode fluorescent lamp outer tube capable of producing an energy efficient external electrode lamp even when the lamp ambient temperature increases.

  As a result of various studies, the present inventor has found that the above object can be achieved by constituting the lamp envelope itself functioning as a dielectric with glass having excellent electrical characteristics even in a high temperature region. It is what we propose.

That is, the fluorescent lamp outer tube of the present invention is a fluorescent lamp outer tube used for manufacturing an external electrode fluorescent lamp having a structure in which electrodes are provided in the vicinity of both ends of the outer peripheral surface of the lamp outer tube. The volume resistivity Ω · cm at 150 ° C. of the glass constituting the glass tube is 13 or more in terms of log and is made of glass containing the following composition. By mass _{percentage, SiO 2 20~80%, B 2} O 3 0~40%, Al 2 O 3 0~50%, Li 2 O + Na 2 O + K 2 O 0~ less than 4.5%, _ZrO 2 0~10% MgO 0-30%, CaO 0-30%, SrO 0-30%, BaO 0-30%, ZnO 0-30%, Nb ₂ O ₅ 0-10%, TiO ₂ 0-30%, CeO ₂ 0 _{~10%, WO 3 0~10%,} Sb 2 O 3 0~6%, Cl 2 0~0.5%.

  Further, the outer tube for a fluorescent lamp of the present invention is characterized in that it has a volume resistivity Ω · cm at 250 ° C. of 10.3 or more in terms of log.

  The outer tube for a fluorescent lamp of the present invention is characterized in that it has a volume resistivity Ω · cm at 350 ° C. of 8.3 or more in terms of log.

  Further, the outer tube for a fluorescent lamp of the present invention is characterized by being made of glass having the following composition.

Fluorescent lamp mantle tube of the present invention or may, MgO + CaO + SrO + BaO is characterized in that it consists of glass which is from 1 to 50% by weight.

In the outer tube for the fluorescent lamp of the present invention, Li ₂ O + Na ₂ O + K ₂ O is 2% by mass or more, and (MgO + CaO + SrO + BaO) / (Li ₂ O + Na ₂ O +). It is characterized by being made of glass satisfying the relationship of K ₂ O) ≧ 0.5.

In addition, the outer tube for a fluorescent lamp of the present invention is characterized by being made of glass having a TiO ₂ + CeO ₂ + WO ₃ content of 0.01 to 20% by mass.

The fluorescent lamp envelope of the present invention is characterized in that it is made of glass having a Na ₂ O content of 3% by mass or less.

  The fluorescent lamp envelope of the present invention is characterized in that the wall thickness is 0.1 to 2 mm.

  The fluorescent lamp envelope of the present invention is characterized in that an exhaust pipe is further joined to at least one open end.

  The fluorescent lamp envelope of the present invention is characterized in that a sealing member is further joined to at least one opening end, thereby sealing the opening end.

  The fluorescent lamp envelope of the present invention is characterized in that an electrode layer is further formed on the outer peripheral surface of the glass tube.

  The fluorescent lamp outer tube of the present invention is characterized in that a phosphor layer is further formed on the inner peripheral surface of the glass tube.

  The external electrode fluorescent lamp of the present invention is characterized by using the above-mentioned outer tube.

  In addition, the external electrode fluorescent lamp of the present invention is used as a fluorescent lamp for a lighting device of a liquid crystal display element.

  If the dielectric member for a fluorescent lamp according to the present invention is used, an external electrode lamp having good energy efficiency and no abnormal heat generation can be manufactured.

  In addition, the fluorescent lamp manufactured using the outer tube of the present invention has a long life because there is almost no electrode deterioration because the electrode is outside. In addition, it is possible to consolidate inverter power supplies without the need for capacitors. Moreover, abnormal heat generation hardly occurs. Therefore, it is suitable as a lamp for an illumination device for a liquid crystal backlight that is inexpensive and highly reliable.

  As a fluorescent lamp having a structure that does not use an internal electrode that tends to affect the lamp life, an external electrode lamp in which electrodes are arranged in the axial direction of the external surface of the lamp is known in addition to the external electrode lamp that is the subject of the present invention. (For example, Patent Document 2).

  For example, Patent Document 3 proposes a glass used for an outer tube of this type of lamp. However, in this outer electrode lamp structure, since the electrode is provided on the entire outer surface of the outer tube, insulation is achieved by coating a transparent resin on the entire outer periphery of the lamp including the electrode. When the transparent resin is irradiated with light, there is a problem that the transparent resin is deteriorated and easily colored, and the luminance of the lamp cannot be maintained for a long time. Further, due to the presence of the electrode, the generated light is reflected inside the lamp, which is inferior in efficiency. For this reason, the external electrode lamp is suitably used for applications that generate intense light instantaneously and do not require continuous lighting, such as a copying machine.

  On the other hand, the external electrode fluorescent lamp which is the subject of the present invention is used in applications where continuous lighting for a long time is performed, for example, a backlight for liquid crystal. In this type of application, it is necessary to maintain the lamp brightness over a long period of time. Therefore, an electrode is provided in the vicinity of both ends of the outer peripheral surface of the outer tube, and resin is coated only on that portion for insulation. By adopting such a structure, there is an advantage that it is not necessary to form a transparent resin or an electrode in the light extraction portion, and light can be efficiently extracted from the entire circumference of the lamp mantle tube.

  However, since the external electrode lamp has a smaller electrode area than the external electrode lamp, a high voltage is applied. As a result, the temperature of the glass mantle is easily raised due to the influence of dielectric loss expressed as a function of the product of voltage, frequency, dielectric constant of dielectric, and dielectric loss tangent. In addition, since the external electrode lamp is continuously lit, the temperature is likely to rise at an accelerated rate.

As a result of considering such conditions, the glass constituting the fluorescent lamp envelope of the present invention requires the following characteristics.
(1) The volume resistance is high from 150 ° C to 350 ° C.

When the volume resistance is low, current flows, energy is wasted due to Joule heat, and the luminous efficiency is deteriorated. In addition, Joule heat may cause deformation of the outer tube and fire of surrounding members.
(2) The dielectric loss tangent at 150, 250, and 350 ° C. is as small as possible.

  When an AC high voltage is applied by an inverter, dielectric heat is generated due to dielectric loss of glass. The heat generation first deteriorates the luminous efficiency of the lamp due to waste of energy. Second, when heat is generated, the temperature rises until equilibrium is reached due to heat dissipation of the entire outer tube, but due to the temperature rise, the dielectric loss tangent of the glass increases and the dielectric loss increases, and further heat generation increases and the temperature rises. Eventually, the outer tube is deformed and burns out. Under normal conditions, the electrode temperature is around 150 ° C., but it rarely reaches 250 ° C.

Since dielectric heating is proportional to frequency, dielectric constant, dielectric loss tangent, and voltage, if the frequency and voltage of power supply conditions are constant, dielectric heating can be reduced by reducing the dielectric constant and dielectric loss tangent. The dielectric constant is a factor that greatly influences the design of the dielectric capacitance that secures the electric power sent to the lamp, and the degree of freedom in design is small. Therefore, it is important to reduce the dielectric tangent value of the glass in the lamp driving temperature range in order to reduce the dielectric heating. In addition, if the dielectric loss tangent increases significantly due to temperature rise, the glass itself generates heat, which increases the dielectric loss of the glass itself, and further repeats a vicious cycle that causes the temperature to rise, eventually leading to burning of the outer tube. It is important that the dielectric loss from 150 ° C. to 250 ° C. is less changed by temperature. Further, in order to prevent burning of the outer tube, the dielectric loss amount at 350 ° C. needs to be sufficiently small.
(3) Low alkali content. In particular, the Na ₂ O content should be as low as possible.

  Alkali components are required to be as small as possible because they greatly affect the dielectric loss tangent and volume resistance value at high temperatures. In particular, Na ions have a large effect on lowering the volume resistivity of glass. Moreover, it is known that ion exchange with Hg is easy, and it is desired to limit the use to the limit. Since K ions and Li ions also have a function of increasing dielectric loss, it is better not to contain them if possible.

However, if it is unavoidable to reduce the viscosity of the glass or increase the productivity, it can be dealt with by introducing abundant alkaline earth components at the same time when it contains an alkali component of 2% by mass or more.
(4) The heat resistant temperature is sufficiently high.

  Since the phosphor is fired at about 500 ° C., a heat resistant temperature of 500 ° C. or higher is required. If the heat-resistant temperature is 600 ° C. or higher, it is easy to form an electrode on the outer peripheral surface of the glass tube using a metal paste, and it is convenient because an electrode having good adhesion can be formed simultaneously with the phosphor firing. Note that the firing temperature of the metal paste is not limited to 600 ° C., and may be fired at a temperature suitable for the material.

If the heat-resistant temperature is low, the outer tube is deformed and it is difficult to manufacture a fluorescent lamp.
(5) Excellent in ultraviolet shielding property and solarization property In a liquid crystal backlight, since an organic member such as a reflector is provided in the vicinity of the fluorescent lamp, the light quantity may be attenuated due to deterioration of organic matter due to ultraviolet rays. For this reason, the glass for the outer tube is required to have an ultraviolet shielding property so that ultraviolet rays generated inside the fluorescent lamp are not leaked to the outside.

  Further, when ultraviolet rays hit the glass, glass coloring (solarization) occurs, but if coloring occurs, the amount of light of the lamp decreases, which is not preferable. For this reason, it is necessary to cope with the composition so that the glass is not colored.

  The outer tube of the present invention that satisfies the required characteristics will be described in detail below.

  The outer tube of the present invention is made of glass having a high volume resistance. The volume resistance is a numerical value indicating the insulating property of glass. If the resistance is small, an electric current flows and the glass generates heat due to Joule heat, so a value as high as possible is required.

  The volume resistivity Ω · cm at 150 ° C. is 13.0 or more, preferably 13.5 or more, and more preferably 14.0 or more in terms of log. If it is 13.0 or more, it shows a sufficient resistance with no practical problem. If it is 13.5 or more, the influence on the dielectric loss is reduced, and if it is 14.0 or more, it can be regarded as a complete insulator.

  The volume resistivity Ω · cm at 250 ° C. is preferably 10.3 or more, preferably 10.5 or more, more preferably 11 or more, particularly 12 or more in terms of log. If it is 10.3 or more, it shows resistance with no practical problem, and if it is 10.5 or more, the effect on dielectric loss is small. Can be used. If it is 12 or more, it is safer.

  The volume resistivity Ω · cm at 350 ° C. is 8.3 or more, preferably 8.5 or more, particularly 9 or more in terms of log. If the volume resistivity is 8.3 or more, a practically satisfactory resistance is shown, and if the volume resistivity is 8.5 or more, the lamp can be used even under severe use conditions where the ambient temperature of the lamp becomes high. If it is 9 or more, it is safer.

  The outer tube of the present invention is made of glass having a small dielectric loss tangent.

  The dielectric property of 1 MHz is a value representative of the property of the substance. In the present invention, a glass having a dielectric loss tangent at 1 MHz of 0.003 at room temperature, preferably 0.0025, more preferably 0.002 or less should be used. It is. 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.

  The lamp is used at 40 KHz to 100 KHz, but the dielectric loss tangent tends to decrease with increasing frequency, so the dielectric loss tangent at 40 KHz is higher than that at 100 KHz. Therefore, the dielectric properties of the glass for the outer tube can be defined by a value of 40 KHz. 150 ° C. is the normal operating temperature of the lamp, and 250 ° C. is the temperature that can occur inside the lamp. Furthermore, 350 ° C. is a temperature that should be considered from the viewpoint of safety.

  The dielectric loss tangent at 150 ° C. and 40 kHz is usually larger than 0.0005, but is desirably 0.005 or less, preferably 0.004 or less, and more preferably 0.003 or less. If it is 0.005 or less, 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 0.004 or less, a lamp having a high operating temperature can be used. Furthermore, if it is 0.003 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 0.02 or less, preferably 0.015 or less, more preferably 0.01 or less. If it is 0.02 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 0.015 or less, it can be used even at a lamp operating temperature high. If it is 01 or less, it is possible to use a type that generates a large amount of heat, such as a high-output type fluorescent lamp, which is preferable.

  The dielectric loss tangent at 350 ° C. and 40 kHz is 0.1 or less, preferably 0.07 or less, more preferably 0.05 or less. If it is less than or equal to 0.1, 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. If the temperature is 0.07 or less, a lamp having a high lamp operating temperature can be used, and if it is 0.05 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.

  Moreover, it is desired that the dielectric loss tangent change rate represented by the following formula is an average value between 150 ° C. and 250 ° C., 0.0002 or less, preferably 0.0001 or less, and more preferably 0.00008 or less. If it is 0.0002 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 0.0001 or less, the influence of the external environment of the lamp is reduced, and 0.00008 or less. If so, the calorific value of the lamp is reduced, which is extremely ideal for the environment.

  Moreover, it is desired that the dielectric loss tangent change rate represented by the following formula is an average value between 250 ° C. and 350 ° C., 0.001 or less, preferably 0.0007 or less, and more preferably 0.0005 or less. If it is 0.001 or less, abnormal heat generation due to an increase in dielectric loss accompanying a temperature rise can be suppressed, so that the outer tube can be prevented from being burned out. If it is 0.007 or less, the outer tube is not easily burned even under the condition that the heat radiation from the lamp is limited, but more ideally if it is 0.005 or less, the temperature of the lamp can be further stabilized. preferable.

Dielectric loss tangent change rate = ΔDielectric loss tangent / ΔT
ΔDielectric loss tangent: Difference in dielectric loss tangent
△ T: In difference present invention measured temperature of the dielectric characteristics (° C.), as the glass used as a mantle tube material, for example, by mass _{percentage, SiO 2 20~80%, B 2} O 3 0~40%, Al 2 O ₃ 0-50%, Li ₂ O + Na ₂ O + K ₂ O 0- less than 4.5% , ZrO ₂ 0-10%, MgO 0-30%, CaO 0-30%, SrO 0-30%, BaO 0 30%, ZnO 0-30%, Nb ₂ O ₅ 0-10%, TiO ₂ 0-30%, CeO ₂ 0-10%, WO ₃ 0-10%, Sb ₂ O ₃ 0-6%, Cl ₂ Contains 0-0.5% composition. The reason for limiting the range of each component will be described below.

SiO ₂ is a main component and a skeletal component of glass. The SiO ₂ content is preferably 20 to 80%, more preferably 20 to 60%, and even more preferably 40 to less than 55%. When the amount of SiO ₂ is more than 20%, the above-described effects are obtained, which is preferable. If it is 40% or more, the weather resistance is improved, and it is possible to prevent alkali blown or the like that makes the glass surface white. If it is less than 80%, the moldability when the molten glass is directly formed into a tube is improved. If it is 60% or less, the viscosity of the glass is lowered, the productivity is improved, and it is suitable for mass production. In the case where it is required to perform a more precise molding with less composition of the alkali component is preferably in the SiO ₂ less than 55% in order to lower the glass viscosity.

B ₂ O ₃ is a component that improves the meltability, the expansion, the viscosity, and the chemical durability, and its content is 0 to 40%, preferably 0 to 30%. When B ₂ O ₃ is 40% or less is preferable because easily becomes uniform glass evaporates less from the glass melt. When it is 30% or less, the evaporation of the glass component is preferably reduced even during heat processing during the lamp manufacturing process.

Al ₂ O ₃ is a component that greatly improves the devitrification property of glass and is a component that facilitates melting and forming of glass. The content is 0 to 50%, preferably 0.5 to 50%. If Al ₂ O ₃ is 0.5% or more, the above effect can be obtained. If it is 50% or less, melting and processing are industrially easy.

Even if a small amount of the alkali component is used, the temperature of the glass is lowered, and there is an effect of obtaining a glass suitable for mass production. Also the effect of acting as a fusing material to facilitate melting the raw material of the glass, but cause ionic conduction in a high temperature state, there is also a disadvantage that tends to cause an increase in the degradation and dielectric loss tangent of the volume resistivity. In particular , when a lamp is used in a situation where heat generation is very likely to occur due to deterioration of volume resistance or increase of dielectric loss tangent, it is desirable to limit the total amount of Li ₂ O + Na ₂ O + K ₂ O to less than 4.5%. . If the content of the alkali component is limited, the above-mentioned drawbacks can be compensated by introducing an alkaline earth component.

Na ₂ O is preferably 3% or less, preferably 1% or less, and particularly preferably 0.1% or less, because the dielectric loss tangent and volume resistance in the high temperature range are improved. The content of Li ₂ O is preferably 3 % or less. K ₂ O is less than 4.5%. Note Na 2 _{if O} the use more than 2%, yet preferably it is possible to suppress the deterioration of the volume resistivity in a high temperature range by using the Li 2 _O and K _{2 O} at the same time.

ZrO ₂ is a component that increases the chemical stability of the glass and has the effect of preventing glass from being blown with alkali or alkaline earth. The content is 0 to 10%, preferably 0.001 to 5%. If ZrO ₂ is 0.001% or more, the above effect can be obtained. Further, if it is within 10%, a stable glass without devitrification is obtained, and if it is 5% or less, it is more preferable.

  The alkaline earth components MgO, CaO, SrO and BaO have the effect of suppressing the movement of the alkali component in the glass and the effect of stabilizing the glass and preventing devitrification from occurring in the glass. Their contents are each 0 to 30%, preferably 0 to 20%. If each component is 30% or less, a stable glass can be obtained without causing alkaline earth devitrification, and more preferably 20% or less. The use of two or more alkaline earth components is preferable because the above effects can be obtained more easily.

  When using a plurality of alkaline earth components, the total content is preferably 1 to 50%, particularly preferably 2 to 40%. When the content is 1% or more, the above effect starts to appear, but in order to obtain the effect with certainty, it is desirable to contain 2% or more. Further, if it is 50% or less, a stable glass can be obtained without causing alkaline earth devitrification, and if it is 40% or less, devitrification is less likely to occur, and the fire resistance of the melting furnace, which is the cause of devitrification, is generated. The restrictions on the use of things can be relaxed.

  When it is unavoidable to introduce an alkali component of 2% or more in total due to reasons such as improving the productivity of glass, by introducing an alkaline earth component at an appropriate ratio, the dielectric loss tangent and volume resistance of the high temperature range are reduced. Deterioration can be mitigated. In this case, the relaxation effect is increased by introducing two or more alkaline earth components, preferably three or more.

In the case where the alkali component is contained in an amount of 2% or more, (MgO + CaO + SrO + BaO) / (Li ₂ O + Na ₂ O + K ₂ O) is 0. It is preferably 5 or more, particularly 0.9 or more, and more preferably 1.5 or more. If this ratio is 0.5 or more, the above-mentioned effect starts to appear, and in order to obtain the effect with certainty, it is desirable to set it to 0.9 or more. Further, if it is 1.5 or more, heat generation such that the outer tube is deformed hardly occurs even in an environment where the outer tube is exposed to a high temperature.

  ZnO is a component effective for reducing the temperature of the glass, and its content is 0 to 30%, preferably 0 to 15%. If it is less than 30%, it becomes possible to obtain a stable glass without devitrification, and if it is 15% or less, it is more preferable.

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

TiO ₂ has an effect of preventing solarization and shielding ultraviolet rays. Moreover, it is a component which raises the dielectric constant of glass, and when a high dielectric constant is required, it is preferable to contain. Its content is 0-30%, preferably 0-10%. If it is less than 30%, it can be stably produced without causing devitrification in the glass, and if it is less than 10%, further stabilization of the process can be expected.

CeO ₂ and WO ₃ are effective in shielding ultraviolet rays and preventing solarization. The content of each component is 0 to 10%. If it is less than 10%, it can be stably produced without causing devitrification in the glass.

TiO ₂ , CeO ₂ and WO ₃ are preferably contained in order to shield ultraviolet rays, and the total content is preferably 0.01 to 20%, particularly preferably 0.1 to 20%. . The above effect can be confirmed if it is 0.01% or more, but it is desirable to contain 0.1% or more in order to surely obtain the above effect. Moreover, if it is 20% or less, it can produce stably, without producing devitrification in glass.

In addition, Ta ₂ O ₅ , MoO ₃ , Bi ₂ O ₃ , rare earth components (Y ₂ O ₃ , La ₂ O _3, etc.) can be introduced at 40% or less as components for adjusting the dielectric constant. Also it is contained _{SnO 2, Sb 2 O 3,} As 2 O 3, SO 3 , etc. as a fining agent component is also possible. However, As ₂ O ₃ should not be used from the environmental aspect. Further, when CeO ₂ and Sb ₂ O ₃ or As ₂ O ₃ coexist, the ultraviolet solarization resistance tends to deteriorate. Fe ₂ O ₃ is a component that is not only included in inexpensive glass materials but is also included in commercial glasses because it is mixed in from the process. However, in order to cause glass coloring, the content of the present invention should be limited to 0.1% or less, particularly 0.03% or less, and further 0.02% or less.

  The moisture contained in the glass has the function of reducing the low temperature viscosity of the glass and improving the workability. On the other hand, however, if it is released as gas into the lamp, the brightness of the lamp may be reduced. In addition, the amount of moisture is also related to the dielectric loss tangent, and it is advantageous to reduce the amount of moisture in order to further reduce the dielectric loss tangent.

  For this reason, it is preferable to properly manage the water content. Specifically, when the coefficient X obtained by the following formula is 1.2 or less, the gas is hardly released and the above problem is hardly caused. Moreover, if it is 0.1 or more, it becomes easy to process the lamp stably. A preferable range of the coefficient X is 0.1 to 0.8, and more preferably 0.1 to 0.6.

  The water content is proportional to the infrared transmittance coefficient (X) represented by the following formula.

X = (log (a / b)) / t
a: Transmittance (%) of a minimum point near 3840 cm ⁻¹
b: Transmittance (%) of the minimum point near 3560 cm ⁻¹
t: Sample measurement thickness (mm)
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 thickness of the outer tube of the present invention is preferably thin in order to ensure the capacitance, but is preferably thick in order to maintain the strength. Therefore, the thickness is preferably 0.1 mm or more, preferably 0.2 mm or more, 2 mm or less, more preferably 1 mm or less. The outer diameter of the outer tube is preferably 1 to 12 mm, particularly 1 to 6 mm from the viewpoint of luminous efficiency.

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

  First, 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 tubular glass is cut into a predetermined size, and post-processed as necessary, whereby a fluorescent lamp outer tube can be obtained.

  Using the outer tube thus obtained, an external electrode fluorescent lamp can be produced according to a conventional method. Prior to assembling the fluorescent lamp, an electrode can be formed on the outer surface of the outer tube, or a layer made of a phosphor or an electron emitting material can be formed on the inner surface. Further, an exhaust pipe can be joined to the opening end of the outer tube or a sealing member can be provided.

Hereinafter, the present invention will be described based on examples. Table 1 shows glass materials (samples A to I ) constituting the outer tube. Samples E, F, H, and I are reference examples.

  First, after preparing a glass raw material so that it might become the composition of Table 1, it melt | dissolved at 1550-1650 degreeC for 8 hours using the platinum crucible. The glass materials used are stone powder, alumina, boric acid, zircon, titanium oxide, magnesium oxide, calcium carbonate, strontium carbonate, barium carbonate, zinc white, lithium carbonate, sodium carbonate, potassium carbonate, sodium chloride, niobium oxide, titanium oxide, oxide Such as cerium, tungsten oxide, and antimony oxide. This is an example and is not limited to the type of raw material. Moreover, the component shown by a composition is a conversion value and is not limited to the description oxide valence.

  Next, the glass melts A to I were formed into a tubular shape by a downdraw method and then cut into a predetermined length to obtain an outer tube made of a transparent glass tube. As other tube forming methods, a Dunner method, an updraw method, or the like can be applied.

The outer tube thus obtained had a linear thermal expansion coefficient of 38 to 95 × 10 ⁻⁷ / ° C. and a strain point of 450 ° C. or higher. The volume resistivity (log display) was 13 or more at 150 ° C., 10 or more at 250 ° C., and 8 or more at 350 ° C.

  The strain point is a measure of the heat resistance of the glass outer tube and is measured according to JIS R3103. If the temperature is below the strain point, the glass can be handled like a ceramic without being deformed by firing during phosphor or external electrode coating, but the viscosity is so hard that the strain point is industrially sufficient. Therefore, the actual heat resistant temperature is 80 ° C. higher than the strain point. The volume resistivity was measured as follows. First, a gold electrode was formed by vapor deposition on a # 1000 polished plate glass sample having a 5 cm square and a thickness of 1 mm. Subsequently, the sample was held in an electric furnace equipped with electrodes so as to be sandwiched between the electrodes. Thereafter, the resistance value at a predetermined temperature was measured using a high resistance measuring device.

  Next, an external electrode fluorescent lamp was manufactured using these mantle tubes.

Table 2 shows examples (sample Nos. 1 to 4 and 7 ) of the external electrode fluorescent lamp of the present invention. The sample No. Reference numerals 5, 6, 8 , and 9 are reference examples.

  Each fluorescent lamp was produced as follows according to the lamp type shown in the table. In the table, the types of lamps mean that the samples A to C are external electrode fluorescent lamps of the first form, and the samples D to I are external electrode fluorescent lamps of the second form.

  A method for manufacturing the fluorescent lamp of the first embodiment will be described. In the fluorescent lamp of the first form, a sealing member and an exhaust pipe are respectively bonded to both opening ends of an outer tube in which an electrode is formed on an outer peripheral surface in advance and a phosphor layer is formed on an inner peripheral surface using sealing glass. It has the structure to do. 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 tube 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. 1A, the sealing member 1, the sealing glass tablet 2, the outer tube 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.

  Here, the outer tube 4 is a transparent glass tube made of the glass of Table 1 and having an outer diameter of 4 mm, a thickness of 0.5 mm, and a length of 500 mm. A phosphor 6 is applied in advance to the inner peripheral surface of the glass tube. Excess phosphor near the ends of the glass tube is removed with a brush. The applied phosphor 6 is baked onto the inner peripheral surface of the glass tube at the time of baking for subsequent electrode baking to form a phosphor layer.

  The electrode 3 formed in advance on the outer tube 4 is made of the materials shown in Table 2. 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 tube and sintering in nitrogen at 600 ° C. As an electrode, there is a method of adhering an aluminum foil with an adhesive. When using aluminum, a ring having a wall thickness of 0.03 to 3 mm, preferably 0.1 to 1 mm, is heated to a temperature about 200 ° C. higher than that of the glass tube to be expanded, and then is inserted into the glass tube and caulked. For example, good results can be obtained in terms of dielectric capacitance.

  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) A tablet having an outer diameter of 4 mm, an inner diameter of 3 mm, and a thickness of 0.3 mm 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 a mantle tube.

  Further, the sealing member 1 is formed into a disk shape having a diameter of 4 mm and a thickness of 2 mm after granulating by adding a binder to glass powder obtained by pulverizing an outer tube glass with an alumina ball mill and classifying with a sieve having an opening of 200 μm. Are press-molded and 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. 1B, 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. 1 (c))
Then, the exhaust pipe 5 is cut off to obtain a first type of fluorescent lamp as shown in FIG.

  Note that either one or both of the joining of the outer tube 4 and the exhaust tube 5 may be performed by direct fusion.

  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. 2A, the phosphor 6 is applied to the inside of the outer tube 4. At that time, excess phosphor is removed with a brush. Further, a metal paste for electrode formation is applied to the outer periphery of the outer tube 4 as shown in Table 2. 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. 2 (b), after melting and sealing one end portion of the outer tube, exhaust, introduction of Ar and Ne gas, and insertion of a mercury amalgam boat are performed from the other end. (Fig. 2 (c))
Next, the opening is sealed, and the mercury amalgam boat is further induction-heated to introduce Hg into the pipe. (Fig. 2 (d))
Thereafter, the portion of the outer tube where the mercury amalgam boat 7 is present is cut off to obtain a fluorescent lamp of the second form. (Fig. 2 (e))
In the fluorescent lamp of the second form, when the outer tube is made of glass having insufficient heat resistance, a metal paste material that can be fired 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 tube and the other end is melt-sealed.

  The external electrode type fluorescent lamp assembled as described above was evaluated for lamp illuminance, parallel lighting, ultraviolet shielding, solarization, and abnormal heating.

  As a result, when compared with the conventional cold cathode lamp 21 (FIG. 3) that was lit under the same conditions, each lamp was not inferior or the lamp of this example was brighter. In addition, lamps can be lit in parallel to the inverter power supply, indicating that power supply can be consolidated. It was found that both the ultraviolet shielding property and the solarization resistance were good. For abnormal heating, the temperature near the outer tube was No. Except for 9, it was about 150 ° C., and no abnormality was observed. No. The lamp No. 9 has a temperature higher than that of the other lamps and is about 240 ° C., so it is indicated by “Δ”. In addition, although sufficient verification about brightness maintenance has not been performed, it has been confirmed that stable brightness maintenance is exhibited at the 100 hr level.

The lamp illuminance was evaluated through observation through a filter, and was compared with a cold cathode lamp lit under the same conditions. As for the parallel lighting property, as shown in FIG. 4, the external electrode fluorescent lamps 22 were arranged in parallel, and it was investigated whether lighting was possible without using a capacitor. In this test, for safety, a power source was used in which the breaker worked when the average current of one lamp exceeded 100 mA. The UV shielding property was measured at a wavelength of 254 nm using a commercially available illuminometer, and 0.1 mW / cm ² or less was determined to be good at a distance of 3 cm. The solarization property was determined to be good when the transmittance of a spectrophotometer 400 nm after irradiation before ultraviolet irradiation was measured on a mirror-polished 1.0 mm thick glass plate and the transmittance difference was 0.5% or less. Irradiation with ultraviolet rays was performed for 1 hour using an ozone cleaning apparatus (Iwasaki Electric OC-2650) at an irradiation distance of 20 mm. For abnormal heating, the lamp ambient temperature was measured, and when heating above 250 ° C. was recognized, it was recognized as abnormal heating.

  The fluorescent lamp of the present invention can be used as a fluorescent lamp for an illumination device (hereinafter referred to as a backlight unit) of a transmissive liquid crystal display element mounted on a notebook personal computer, a TV monitor, a personal computer (PC) monitor, an in-vehicle instrument or the like. is there. Further, the outer tube of the present invention can be used as a structural member of such a fluorescent lamp.

It is explanatory drawing which shows the method of manufacturing the fluorescent lamp of a 1st form. It is explanatory drawing which shows the method of manufacturing the fluorescent lamp of a 2nd form. It is explanatory drawing which shows the conventional cold cathode lamp. It is explanatory drawing which shows the state which arranged the external electrode fluorescent lamp of this invention in parallel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing member 2 Sealing glass tablet 3 Electrode 4 Mantle tube 5 Exhaust tube 6 Phosphor 7 Mercury amalgam boat 10 Carbon type 11 Exhaust device 21 Conventional cold cathode lamp 22 External electrode fluorescent lamp of the present invention

Claims (13)

An outer tube for a fluorescent lamp having a structure in which electrodes are provided in the vicinity of both ends of an outer peripheral surface of a lamp envelope, and is made of a transparent glass tube, and 150 of the glass constituting the glass tube. The volume resistivity Ω · cm at 0 ° C. is 13.0 or more in terms of log, and the glass composition is SiO ₂ 20-80%, B ₂ O ₃ 0-40%, Al ₂ O ₃ 0 in terms of mass percentage. _{~50%, Li 2 O + Na} 2 O + K 2 O 0~ less than _{4.5%, ZrO 2 0~10%,} 0~30% MgO, CaO 0~30%, SrO 0~30%, BaO 0~30%, _{0~30% ZnO, Nb 2 O 5} 0~10%, TiO 2 0~30%, CeO 2 0~10%, WO 3 0~10%, Sb 2 O 3 0~6%, Cl 2 0~0 . Made of glass containing 5% An outer tube for a fluorescent lamp characterized by: 2. The fluorescent lamp envelope according to claim 1, wherein the volume resistivity Ω · cm at 250 ° C. is made of glass having a log representation of 10.3 or more. 3. The fluorescent lamp envelope according to claim 1, wherein the volume resistivity Ω · cm at 350 ° C. is made of glass having a log display of 8.3 or more. The outer tube for a fluorescent lamp according to any one of claims 1 to 3 , wherein the outer tube is made of glass containing 1 to 50 mass% of MgO + CaO + SrO + BaO. Li ₂ O + Na ₂ O + K ₂ O is 2% by mass or more and (MgO + CaO + SrO + BaO) / (Li ₂ O + Na ₂ O + K ₂ O) ≧ 0.5 The outer tube for a fluorescent lamp according to any one of claims 1 to 4 , wherein the outer tube is made of filled glass. Fluorescent lamp mantle tube according to any one of claims 1 to 5, TiO ₂ + CeO ₂ + WO ₃ is characterized in that it consists of glass is 0.01 to 20 mass%. Fluorescent lamp mantle tube according to any one of claims 1 to 6, characterized in that the Na 2 _O content of of 3 wt% or less of the glass. At least one opening end, further fluorescent lamp mantle tube according to any one of claims 1 to 7, the exhaust pipe is characterized by comprising bonded. The fluorescent lamp envelope according to any one of claims 1 to 8 , wherein a sealing member is further joined to at least one open end, whereby the open end is sealed. The fluorescent lamp envelope according to any one of claims 1 to 9, wherein an electrode layer is further formed on the outer peripheral surface of the glass tube. The fluorescent lamp envelope according to any one of claims 1 to 10 , further comprising a phosphor layer formed on an inner peripheral surface of the glass tube. An external electrode fluorescent lamp having a structure in which electrodes are provided in the vicinity of both ends of an outer peripheral surface of a lamp mantle tube, wherein the mantle tube according to any one of claims 1 to 11 is used. lamp. The external electrode fluorescent lamp according to claim 12 , wherein the external electrode fluorescent lamp is used as a fluorescent lamp for an illumination device of a liquid crystal display element.