WO2007055379A1

WO2007055379A1 - External electrode driven discharge lamp, method for producing same, and liquid crystal display

Info

Publication number: WO2007055379A1
Application number: PCT/JP2006/322661
Authority: WO
Inventors: Seiichirou Fujioka; Susumu Takahashi
Original assignee: Nec Lighting, Ltd.
Priority date: 2005-11-14
Filing date: 2006-11-14
Publication date: 2007-05-18
Also published as: JP4309393B2; CN101310363B; CN101310363A; KR20080069243A; JP2007134289A; KR100940372B1

Abstract

Disclosed is an external electrode driven discharge lamp comprising a hollow glass bulb (1) forming a hermetically sealed space, a discharge gas sealed in the glass bulb, and an external electrode (22) arranged outside the glass bulb. The external electrode is a plate composed of a conductive material, and is connected to the glass bulb with a fusion-bonding layer (5) whichi is composed of a solder alloy. The solder alloy is an alloy of bismuth and tin containing 30-70% by weight of bismuth. Since the linear expansion coefficient of the glass bulb is almost equal to the linear expansion coefficient of the solder alloy, damages to the glass bulb caused by thermal impact during production can be suppressed.

Description

Specification

External electrode type discharge lamp, method for manufacturing the same, and liquid crystal display device

Technical field

The present invention relates to a structure of an external electrode type discharge lamp used for a backlight of a liquid crystal display panel, a manufacturing method thereof, and a liquid crystal display device using the external electrode type discharge lamp as a backlight.

Background art

In a liquid crystal display device, it is necessary to apply external force illumination light in order to visualize an electronic image formed on the liquid crystal display panel. This illumination method includes a passive illumination method using ambient light and an active illumination method using a light source such as a cold cathode fluorescent lamp or a light emitting diode on the back side or the front side of the liquid crystal display panel. Among the active illumination methods, the size of the liquid crystal display panel is large, and in large display devices, a light source arranged on the back of the liquid crystal display panel, the so-called backlight, is generally used, and the use of fluorescent lamps as the size increases There are problems such as an increase in the manufacturing cost due to the increase in the number, and there is a demand for improvements in fluorescent lamps.

[0003] As a fluorescent lamp for knocklights, a cold cathode fluorescent lamp and an external electrode fluorescent lamp are used. In general, a pair of internal electrodes are provided in the fluorescent lamp, and a voltage is provided between the electrodes. In general, a cold cathode fluorescent lamp having a structure in which electric discharge is generated by discharging a mark is generally used. However, cold cathode fluorescent lamps cannot handle thinning of the display, reduction of power consumption, production cost, etc., and external electrode type fluorescent lamps that can be expected to reduce production cost and power consumption will attract attention. Became. As this external electrode type fluorescent lamp, Japanese Patent Application Laid-Open No. 2003-91007 discloses a configuration in which short tubular metal electrodes are respectively provided outside both ends of a glass tube.

Disclosure of the invention

[0004] By the way, in the external electrode fluorescent lamp as described above, in order to avoid problems such as variations in lamp current when a plurality of fluorescent lamps are lit in parallel and local temperature rise in the external electrode portion. The glass tube and the metal material constituting the external electrode must be in close contact. There is a point. However, in order to overcome the above-mentioned problems, the gap between the outer surface of the glass tube and the inner surface of the external electrode is mainly composed of tin. It is considered to join by filling with a solder alloy.

[0005] On the other hand, a solder alloy mainly composed of tin has an average linear expansion coefficient of about 230 X 10 " ⁶ cm / cm / ° C to 250 X 10 ^_6 cm / cm / ° C. Coefficient of linear expansion 51 X 10 " ⁶ c mZcmZ ° C The melting point is much larger than 210 ° C to 230 ° C, and the soldering temperature during operation is around S250 ° C.

[0006] For this reason, when a solder alloy fusion layer is provided in the gap between the glass tube and the external electrode, the end portion of the glass tube to which the external electrode is attached is immersed in a molten solder alloy solder bath. The glass tube may be damaged by thermal shock. In addition, even after the external electrode is soldered to the glass tube, when the solder alloy is solidified, the glass tube may be damaged due to the difference in coefficient of linear expansion between the solder alloy and the glass tube. However, there is a problem that sufficient reliability cannot be obtained as a backlight lamp of a liquid crystal display device.

[0007] Therefore, the present invention provides an external electrode type discharge that can prevent the occurrence of damage after attaching an external electrode to an envelope, and improve reliability. An object of the present invention is to provide a lamp, a manufacturing method thereof, and a liquid crystal display device.

In order to achieve the above-described object, an external electrode type discharge lamp according to the present invention includes an envelope made of a glass material that forms a hollow hermetic space, and a discharge medium sealed inside the envelope. A body gas and an external electrode provided on the outer surface of the envelope for causing a dielectric barrier discharge in the gas of the discharge medium. Further, the external electrode is made of a conductive material plate and is joined by a solder alloy fusion layer provided around the outer surface of the envelope. The solder alloy contains bismuth in the range of 30% to 70% by weight, with the balance being tin.

[0009] According to the external electrode type discharge lamp of the present invention configured as described above, the non-linear alloy forming the fusion layer contains bismuth, so that the linear expansion of the envelope made of the glass material can be achieved. Since the coefficient of thermal expansion of the solder alloy can be made close to the coefficient, damage due to thermal shock can be suppressed when the external electrode is joined to the envelope with a solder alloy. In addition, according to the external electrode type discharge lamp, the fusion layer of the solder alloy is favorably formed between the external electrode and the envelope. Therefore, for example, when a plurality of discharge lamps are lit in parallel, variations in lamp current are reduced, and a local temperature rise in the external electrode portion can be suppressed. As a result, the reliability of the external electrode type discharge lamp is improved and manufacturing defects are reduced.

[0010] Further, in the external electrode type discharge lamp according to the present invention, it is preferable that copper is added to the solder alloy in the range of 0.01 wt% to 2 wt% in addition to bismuth and tin. By adding copper, the molten solder alloy is easily spread, and the solder alloy is easily adhered to the outer surface of the envelope.

In addition, the liquid crystal display device according to the present invention includes the above-described external electrode type discharge lamp according to the present invention.

In addition, an external electrode type discharge lamp is used as a backlight of the liquid crystal display panel.

[0012] In addition, the manufacturing method of the external electrode type discharge lamp according to the present invention includes an envelope made of a glass material that forms a hollow airtight space, and a gas of a discharge medium sealed inside the envelope. And an external electrode provided on the outer surface of the envelope for causing a dielectric barrier discharge in the gas of the discharge medium. The external electrode extends around the outer surface of the envelope due to the plate force of the conductive material. This is a method for manufacturing an external electrode type discharge lamp in which a solder alloy is bonded by a fusion layer of a solder alloy, and the solder alloy contains bismuth in the range of 30% by weight and 70% by weight, and the balance is tin. A first step of attaching the external electrode to the envelope, and a second step of forming a fusion layer by pouring a solder alloy between the outer surface of the envelope and the inner surface of the external electrode.

[0013] According to the present invention, the bonding state between the envelope and the external electrode is ensured satisfactorily by the fusion layer of the solder alloy, and the linear expansion coefficient of the envelope made of the glass material is reduced. The linear expansion coefficient of the alloy can be approached. Therefore, according to the present invention, the variation in lamp current when a plurality of discharge lamps are lit in parallel is reduced, and when the external electrode is soldered to the envelope, the discharge is performed after soldering. It is possible to prevent lamp breakage and improve reliability.

Brief Description of Drawings

FIG. 1 is a side view showing an entire external electrode type discharge lamp of a first embodiment.

FIG. 2 is a side view showing an end portion of the external electrode type discharge lamp of the first embodiment.

FIG. 3A is an AA cross-sectional view showing the external electrode type discharge lamp of the first embodiment. FIG. 3B is a cross-sectional view taken along the line BB showing the external electrode type discharge lamp of the first embodiment.

FIG. 4A is a diagram showing a method of soldering external electrodes in the second embodiment.

FIG. 4B is a diagram showing a method of soldering external electrodes according to the second embodiment.

FIG. 5A is a longitudinal sectional view showing an external electrode type discharge lamp of a second embodiment.

FIG. 5B is a longitudinal sectional view showing another example of the external electrode type discharge lamp of the second embodiment.

FIG. 6A is a cross-sectional view showing an external electrode type discharge lamp of a third embodiment.

FIG. 6B is a longitudinal sectional view showing an external electrode type discharge lamp of a third embodiment.

FIG. 7A is a front view showing an example of an external electrode according to a fourth embodiment in a component state.

FIG. 7B is a perspective side view showing an example of the external electrode according to the fourth embodiment in a component state.

FIG. 8A is a front view showing another example of the external electrode according to the fourth embodiment in a component state.

FIG. 8B is a transparent side view showing another example of the external electrode according to the fourth embodiment in a component state.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

[0016] (First embodiment)

FIG. 1 shows an external electrode type discharge lamp of this embodiment. FIG. 2 shows a side view of the end portion of the external electrode type discharge lamp according to the first embodiment of the present invention. 3A and 3B are cross-sectional views showing electrode portions of the external electrode type discharge lamp according to the first embodiment.

3A is a cross-sectional view taken along the line AA, and FIG. 3B is a cross-sectional view taken along the line BB.

As shown in FIG. 1, FIG. 2, FIG. 3A, and FIG. 3B, the external electrode type discharge lamp is a mercury fluorescent lamp, and external electrodes 22 are formed on the outer surfaces of both ends of the cylindrical glass bulb 1. There is one each.

[0018] The external electrodes 22 are electrically insulated from each other. The glass bulb 1 has a light-transmitting hermetically sealed cylindrical shape such as borosilicate glass, for example, and has a medium air-tight space (discharge chamber) inside, such as a mixed gas of argon and mercury vapor. The discharge medium gas is sealed. Examples of the discharge medium gas include a mixed gas of argon and mercury vapor, a rare gas such as argon, neon, krypton, or xenon, or these. A mixed gas of noble gas and mercury vapor is enclosed. The filling pressure is about 1.3 X 10 ³ Pa to 40 X 10 ³ Pa (10 Torr to 300 Torr). The basic structure related to the discharge is the glass bulb 1, the discharge medium gas, and the external electrode 22 described above. In addition, the phosphor layer 4 is provided on the inner surface of the glass bulb 1 on the discharge chamber side. It has been. The phosphor layer 4 plays a role of converting ultraviolet rays generated in the glass bulb 1 by discharge into light of other wavelengths such as visible light. The phosphor is not particularly limited, and an appropriate phosphor is selected according to the wavelength of light to be emitted to the outside.

In addition, a protective layer 3 is formed on the inner surface of the glass bulb 1 corresponding to the bottom of each external electrode 22, and a phosphor layer 4 is formed on the other portions. The protective layer 3 is for protecting the inner surface of the glass nozzle 1 and is made of a metal oxide such as yttrium oxide. The protective layer 3 and the phosphor layer 4 do not affect the function and effect of the present invention even if they are not particularly provided, as will be described later. For this reason, the illustration of the protective layer 3 formed on the inner surface of the glass bulb 1 is omitted in the AA sectional view shown in FIG. 3A.

In the present embodiment, each external electrode 22 is formed in a ring shape by using a belt-like plate having a force such as 42 alloy (Fe—Ni42 alloy) or Kovar (KOV), for example. In the state of the parts before being attached to 1, the inner diameter is made smaller than the outer diameter of the glass bulb 1. However, the circumferential length of the strip-shaped metal plate is sufficiently longer than that of the conventional “C” -shaped electrode, and one end and the other end of the strip are rounded in a ring shape. It has a “deep winding” structure that overlaps at an appropriate distance, and that the overlapping part remains even after it is mounted on the glass nozzle. Such a structure is called “deep winding” or “lap winding”. The length L1 of the portion where the ends overlap is not particularly limited.

In the present embodiment, the inner diameter of the external electrode component having the “deep winding” structure as described above is expanded, and the glass nozzle 1 is passed through the tube in the direction of the tube axis. Cover the glass bulb 1 with the external electrode. After the mounting, the external electrode 22 is fixed by pressing the glass bulb 1 by spring elasticity due to the fact that the inner diameter is larger than that in the component state.

[0022] The external electrode 22 is formed by covering a ring electrode having a deep winding structure on the outside of the glass nozzle 1. Easy to install. Since the external electrode 22 is “deeply wound” and the end portion of the ring shape overlaps the end portion, the end electrode is different from the conventional “C” -shaped external electrode. The light leakage of force between the breaks is eliminated. Further, according to the external electrode 22, the electrode area can be made larger than that of the conventional “C” -shaped external electrode, the amount of heat generation can be reduced, and the heat radiation area can be increased.

[0023] The material of the external electrode 22 is not limited to 42 alloy or KOV. However, considering the relationship with the coefficient of thermal expansion of the borosilicate glass bulb, 42 alloy or KOV that has a coefficient of thermal expansion close to that of the glass valve is preferred. That is, the thermal expansion coefficient of the external electrode 22 is made substantially equal to the thermal expansion coefficient of the glass bulb 1, thereby preventing the glass bulb 1 from being damaged.

[0024] Although not shown in the figure, the inner electrode surface of the external electrode 22 (the surface facing the outer peripheral surface side of the glass bulb 1) is provided with, for example, a structural force prevention by which metal plating is applied by a flash plating method. Is preferable. In particular, since the external electrode 22 is made of an alloy containing iron (Fe) and 42 alloy or KOV, the effect of plating is great. Examples of the plating material include, but are not limited to, metals such as gold and nickel, which are not easily oxidized, and copper, tin, zinc, silver, and the like. It is also effective if the outer peripheral surface of the external electrode 22 is similarly subjected to metal plating.

[0025] In the external electrode type mercury fluorescent lamp configured as described above, for example, frequency: 10 kHz to 100 kHz, voltage: lkV to 10 kV between an external power supply (not shown) and a pair of external electrodes 22. By applying a certain amount of AC power, a dielectric barrier discharge is generated in which the tube wall of the glass bulb 1 is a dielectric. Then, the ultraviolet rays generated by the dielectric barrier discharge excite the phosphor layer 4, and the light converted to another wavelength by the phosphor layer 4 is emitted to the outside through the glass bulb 1.

In the external electrode type discharge lamp of this embodiment, a solder alloy fusion layer 5 is provided between the external electrode 22 and the glass bulb 1. In other words, in the present embodiment, each external electrode 22 is joined to both ends of the glass nozzle 1 by a solder alloy wetting phenomenon, so that there is no contact state unevenness caused by mechanical contact.

[0027] Since the solder alloy is a metal material, there is no deterioration due to ultraviolet rays. Therefore, follow Unlike external electrodes using conventional adhesives containing organic resin, the bonding state between the external electrode and the glass valve does not deteriorate over time.

[0028] The external electrode 22 according to the present embodiment is manufactured as follows. FIG. 4A shows a state when the external electrode 22 is soldered in this embodiment. As shown in FIG. 4A, first, “deep winding” external electrodes 22 are attached to the outer surfaces of both ends of the glass bulb 1. Then, attach the tip of the solder bar 6 to the edge of the circumference of the outer electrode 22 surrounding the glass bulb 1, and bring the solder rod 7 into contact with the outer electrode 22, so that the glass bulb 1 rotates around the tube axis. Heat and ultrasonic energy are applied to the external electrode 22 while rotating. As a result, the molten solder alloy penetrates into the gap between the external electrode 22 and the glass bulb 1 and the overlap between the electrode ends of the deeply wound portion of the external electrode 22 by capillary action. Soldering is done. Further, the external electrode 22 soldered to the glass bulb 1 is coated with a solder alloy to a degree that is not visible from the outside.

[0029] In the case of attaching and slashing by this method, the glass bulb 1 may be held horizontally or may be set up vertically! /. Before soldering with the glass bulb 1 fitted into the glass bulb 1, the external electrode 22 is fixed to the glass bulb 1 by spring elasticity, so that it slides down from the glass nozzle 1 even when held vertically. There is no hindrance to soldering work. Such a method of soldering while applying heat and ultrasonic energy to an object to be soldered using a soldering iron is called “ultrasonic soldering”.

The soldering of the external electrode is not limited to the “ultrasonic soldering” described above, but can be similarly realized by the “ultrasonic soldering dip method” described below. Figure 4B shows the soldering method using the “ultrasonic soldering method”. As shown in FIG. 4B, the solder alloy is melted in the solder bath 9 including the ultrasonic vibrator 8. Then, the glass bulb 1 is previously covered with an external electrode 22 having a “deep winding” structure, and the glass bulb 1 is immersed in the molten solder 10 to operate the ultrasonic vibrator 8. As a result, the solder alloy penetrates smoothly between the gap between the external electrode 22 and the glass bulb 1 and the overlap between the electrode ends of the deeply wound portion of the external electrode 22, for example, a thickness of 100 m. As a result, a sufficient amount of the fusion layer 5 is formed, and the soldering is performed well.

[0031] Using such a solder bath, while applying ultrasonic energy to molten solder, The soldering method in which the object to be soldered is immersed in molten solder is called the “ultrasonic solder dip method”. In the case of soldering by the ultrasonic solder dip method, the fusion layer 5 is also formed on the end face of the glass nozzle 1 as shown in FIG. 3B.

[0032] In the case of soldering by the ultrasonic solder dave method, the force that normally dries the glass nozzle 1 in the molten solder 10 with the tube axis direction vertical, even in that case, the external electrode 22 before soldering is Since it is fixed to the glass bulb 1 with spring elasticity, there is no problem in the work. According to this ultrasonic solder dip method, the permeability of the solder alloy into the gap between the external electrode 22 and the glass bulb 1 is improved, and the bonding force by the fusion layer is also improved.

[0033] When the external electrode 22 and the glass nozzle 1 are soldered as in this embodiment, a solder alloy fusion layer may be formed directly on the glass bulb, but as a foundation for the fusion layer, It is also a good method to form a plating layer of a metal such as nickel on the outer surface of the glass bulb 1 in advance. By doing so, the familiarity between the fusion layer 5 and the glass bulb 1 becomes better, and the soldering operation becomes easier.

[0034] Here, the solder alloy used for soldering, which is the main part of the present invention, will be described in detail.

[0035] The solder alloy contains bismuth in the range of 30 wt% to 70 wt%, and copper is 0.0.

It is added in the range of 01% to 2% by weight, with the balance being tin.

Bismuth is added for the purpose of reducing the linear expansion coefficient of the solder alloy so that the linear expansion coefficient of the solder alloy approaches that of the glass bulb 1. When bismuth is less than 30% by weight, the effect of reducing the linear expansion coefficient of the solder alloy is poor. If the glass mass is higher than 70% by weight, when the glass bulb 1 is immersed in the molten solder alloy, the so-called “dama” is easily generated, the solder alloy becomes brittle after solidification, and cracking and peeling are likely to occur. There is an inconvenience.

[0037] Copper has a function of facilitating the melting of the solder alloy and is added for the purpose of facilitating adhesion of the solder alloy to the outer surface of the glass bulb 1, and if less than 0.01%, the solder alloy Is not preferable because it becomes brittle after solidification. When it exceeds 2%, the fluidity of the molten solder alloy is lowered, and so-called “dama” is easily generated when the glass bulb 1 is immersed in the molten solder alloy, which is inconvenient. [0038] Then, contact!, The external electrode type discharge lamp of the present embodiment Te, As an example of the component ratio of the solder alloy, bismuth 40 weight ^_0/0, copper 0.1 wt ^_0/0, tin It was optimal to have 59.9% by weight.

[0039] According to the solder alloy according to the above-described embodiment, the optimum wettability with respect to the external electrode 22 and the glass nozzle 1 is ensured, so that the inner peripheral surface of the external electrode 22 and the outer peripheral surface of the glass bulb 1 are The solder alloy penetrates well into the gap by capillary action, and the fusion layer 5 can be formed with a substantially uniform thickness over almost the entire area of the gap. Also, according to this solder alloy, when the external electrode 22 is pulled out after being immersed in the molten solder 10, it is possible to prevent the oxides adhering to the outer inner surface of the outer electrode 22 from remaining on the surface. Thus, a flat fusion layer 5 can be formed satisfactorily.

[0040] Further, as another application of the above-described solder alloy, for example, a configuration in which a current conductor layer is formed as an external electrode on the outer peripheral surface of a glass bulb by an ultrasonic solder dubbing method, for example, JP-A-2004-146351 It is suitable for use in an external electrode type discharge lamp disclosed in the publication. The solder alloy having the above component ratio is used in the ultrasonic solder dubbing method to form the external electrode, so that the wettability of the solder alloy is ensured. Therefore, the glass bulb and the external electrode are connected to the solder bath. When immersed in the outer surface of the solder dubbing layer, it is possible to prevent foreign substances such as oxides from remaining on the outer peripheral surface, and to prevent the unevenness caused by the oxides from forming on the outer peripheral surface. In addition to forming the outer peripheral surface of a flat surface, the fused layer can be formed with a substantially uniform thickness. Therefore, by improving the flatness of the outer peripheral surface of the external electrode, it is possible to prevent peeling of the external electrode and breakage of the glass valve due to unevenness of the oxide, and to supply power to the external electrode. A good contact state is ensured, and productivity and yield can be improved.

[0041] It is also good to form a metal plating layer on the inner peripheral surface of each external electrode 22. In the present embodiment, the inner peripheral surface of the external electrode 22 is soldered and does not come into direct contact with air, so that it has a structure that is resistant to oxidization. Wetting of the solder alloy during soldering Therefore, when immersed in the solder bath, the solder alloy smoothly enters the gap between the external electrode 22 and the glass bulb 1, facilitating the soldering work and improving the soldering reliability. Can do. Sarako, outer surface of external electrode 22 Similarly, by applying metal plating, the fusion layer 5 can be satisfactorily adhered to the outer peripheral surface with a uniform thickness.

[0042] As described above, according to the external electrode type discharge lamp of the first embodiment, the solder alloy force bismuth forming the fusion layer 5 provided across the gap between the external electrode 22 and the glass bulb 1 is provided. By using tin, copper, etc., the linear expansion coefficient of the fusion layer 5 can be brought close to the linear expansion coefficient of the glass bulb 1. Therefore, according to this external electrode type discharge lamp, the glass bulb 1 may be damaged by thermal shock in the process of soldering the external electrode 22 to the glass bulb 1 or the glass bulb 1 may be damaged after soldering. It can be suppressed.

Further, according to this external electrode type discharge lamp, since the solder alloy fusion layer 5 is well formed between the external electrode 22 and the glass bulb 1, for example, a plurality of discharge lamps are arranged in parallel. When the lamp is lit, the variation in lamp current is reduced, and the local temperature rise at the outer electrode 22 is suppressed. As a result, the reliability of the external electrode type discharge lamp is improved, and the manufacturing cost can be reduced by reducing manufacturing defects.

[0044] (Second Embodiment)

5A and 5B are longitudinal sectional views of the external electrodes according to the second embodiment. Referring to FIGS. 5A and 5B and FIGS. 3A and 3B together, in this embodiment, the external electrode having the “deep winding” structure is used V, and the external electrode is made of the above-described solder alloy with glass bulb 1. The point of soldering is the same as in the first embodiment, except that the end face of the external electrode 24 protrudes outward from the end face of the glass bulb 1 in the axial direction. And

With this configuration, as shown in FIG. 5A, in the thin glass bulb, the thickness of the fusion layer 5 formed on the end surface of the glass bulb 1 is such that the glass bulb 1 of the external electrode 24 Depending on the amount of protrusion L2 of the end face force, it is formed thicker than when it is not protruded, so heat dissipation is improved accordingly.

[0046] Further, in the case where the end surface of the glass bulb 1 is a flat surface, as shown in FIG. 5B, the end surface of the glass electrode 1 from which the end surface of the external electrode 24 protrudes is bent. Since 5 becomes thicker, the heat dissipation is improved accordingly.

[0047] (Third embodiment)

FIG. 6A shows a cross-sectional view of the external electrode according to the third embodiment, and FIG. 6B shows the third embodiment. The longitudinal cross-sectional view of the external electrode which concerns on a form is shown. In the cross-sectional view of FIG. 6A, illustration of the protective layer 3 on the inner surface of the glass bulb 1 is omitted for the same reason as in the first embodiment.

[0048] Referring to FIGS. 3A and 3B in combination with FIGS. 6A and 6B, in this embodiment, the external electrode 25 is soldered to the glass valve 1, and the solder alloy used is the first. It is the same as the embodiment. However, this is different from the first embodiment in which an electrode having a “deep winding” structure using a “C” -shaped external electrode is used. The “C” -shaped external electrode 25 used in the present embodiment is obtained by curving a strip of 42 alloy or KOV into a ring shape with a circular cross section. The outer electrode 25 has an inner diameter of the ring that is smaller than the outer diameter of the glass bulb 1 in the state of the parts before being attached to the glass bulb 1, and is expanded after being attached to the glass bulb 1. The ends of the are separated into a “C” shape.

The external electrode 25 of the present embodiment has a “C” -shaped force. As a base of the external electrode 25, the fusion layer 5 soldering the external electrode 25 to the glass bulb 1 is the circle of the glass bulb 1. Since it is provided in the circumferential direction, it is blocked by the optical force fusion layer 5 radiated from the inside of the glass bulb 1 and does not leak to the outside from the `` C '' shaped cut portion of the external electrode 25. .

[0050] Since the external electrode 25 and the glass bulb 1 are fixed to each other by soldering, a mechanical “C” -shaped external electrode made of a metal plate is simply fitted into the glass bulb. Unlike the conventional external electrode which is only in contact, there is no unevenness in the contact state. In addition, since the fusion layer 5 is not deteriorated by ultraviolet rays, the contact state does not deteriorate over time unlike the conventional external electrode in which the “C” -shaped external electrode is fixed to the glass bulb with an adhesive. Yes.

[0051] When forming the external electrode 25 according to the present embodiment, the external electrode 25 is first fitted into the glass bulb 1 as in the second embodiment. Thereafter, the fusion layer 5 is poured between the glass valve 1 and the external electrode 25 by ultrasonic soldering or ultrasonic solder dipping. Even if the glass bulb 1 is set up vertically during soldering, the workability is not reduced as the external electrode 25 does not slide off the glass bulb 1. The “C” -shaped external electrode 25 originally has an inner diameter smaller than the outer diameter of the glass nozzle 1. Therefore, when the glass bulb 1 is fitted, the external electrode itself This is because it is fixed to the glass bulb 1 by the spring elasticity.

[0052] As described above, according to the external electrode type discharge lamp of the present embodiment, the light of the internal force of the glass bulb 1 is caused by the fusion layer 5 provided around the outer surface of the glass bulb 1. Since the light is blocked, light leakage at the external electrode 25 can be eliminated.

[0053] (Fourth embodiment)

FIG. 7A shows a front view of an example of the external electrode according to the fourth embodiment, and FIG. 7B shows a perspective side view of an example of the external electrode according to the fourth embodiment. FIG. 8A shows a front view of another example, and FIG. 8B shows a perspective side view of another example. These FIGS. 7A, 7B and 8A, 8B all show the external electrodes in the state of the parts before being mounted on the glass bulb. With reference to FIG. 7A, FIG. 7B, and FIG. 8A, FIG.

[0054] The cylinder 13 made of a metal plate has an inner diameter larger than the outer diameter of the glass bulb 1, and is provided with a protrusion protruding toward the glass bulb 1 inside. As the protrusion, for example, as shown in FIGS. 7A and 7B, a protrusion 14 having a structure in which the middle of the cylinder 13 is radially narrowed and protruded inward is used. Alternatively, as shown in FIGS. 8A and 8B, a protrusion 15 formed by cutting the side surface of the cylinder 13 into a “U” shape in the tube axis direction and causing it to the inside may be used. In either case, the protrusion L3 of protrusion 14 or protrusion 15 is the diameter of the circle inscribed in the tip of protrusions 14 and 15 in the state of the part before attaching external electrode 26 to glass valve 1. It is sized so that it becomes smaller. After the external electrode 26 is attached to the glass bulb 1, the glass bulb 1 is pressed down by the spring elasticity of the internal projection.

According to the present embodiment, since the external electrode 26 is mainly a cylinder, there is no light leakage through the glass bulb 1 internal force external electrode 26. When the external electrode 26 is assembled to the glass bulb 1, the external electrode 26 is simply fitted along the one end force tube axis direction of the glass bulb 1, so that the assembling work is simple.

[0056] The external electrode 26 shown in FIGS. 7A, 7B, 8A, and 8B is soldered to the glass bulb 1 with the above-described solder alloy, as in the first embodiment (see FIGS. 3A and 3B). ing. In this way, the external electrode made of a metal plate was simply fitted into the glass nozzle. The uneven contact state caused by mechanical contact is eliminated. In this embodiment

When soldering, as in the first embodiment, after the external electrode 26 is fitted into the glass nozzle 1, the glass valve 1 and the external electrode 26 are connected to each other by ultrasonic soldering or ultrasonic solder dipping. By forming a solder alloy into the gap between the two, the fusion layer 5 is formed.

In each of the first to fourth embodiments described above, the external electrode having a structure that is substantially cylindrical and has both end faces open in the tube axis direction is illustrated, but the present invention is limited to this configuration. Not. Although not shown in the drawings, the external electrode may have a cap-like structure in which the end surface near the end surface of the glass bulb is closed. In this way, since the heat radiation area is further increased, the heat radiation effect can be further improved.

[0058] Further, as apparent from the above description, the present invention is not limited to a mercury discharge lamp in which mercury vapor is included in the gas of the discharge medium. The presence or absence of the layer 3 or the material does not affect the operational effects of the present invention.

[0059] In addition, the external electrode type discharge lamp according to the present invention is called a so-called flat plate structure, which is not a case where a cylindrical envelope (glass bulb 1) as described in the embodiment is used. It is also suitable for those having a loose structure. The external electrode type discharge lamp of this structure has a structure in which a pair of external electrodes are provided on the outer surface of the glass plate by creating a medium airtight discharge space with two glass flat plates facing each other at an interval. Speak. Even in this flat electrode type external electrode type discharge lamp, the glass plate and the external electrode made of a metal plate can be joined with a solder. And by comprising in this way, the nonuniformity of the contact state which arises by the structure only of the direct mechanical contact of an external electrode and a glass plate can be improved. In addition, the contact state between the envelope and the external electrode can be prevented from being deteriorated by the ultraviolet rays radiated from the discharge space.

Example

As shown in FIG. 1, FIG. 2, FIG. 3A, and FIG. 3B, in the fluorescent lamp of the example, the external electrodes 22 are respectively provided outside the both ends of the glass valve 1 to cover the external electrodes 22. Thus, a solder alloy fusion layer 5 made of tin, bismuth, and a small amount of copper is provided, and a solder alloy fusion layer 5 is formed in the gap between the glass valve 1 and the external electrode 22. Also implemented The solder alloy used in the example consists of 0% by weight of bismuth, 0.1% by weight of copper and the balance of tin.

[0061] As a structure in which the external electrodes 22 are provided outside the both ends of the glass bulb 1 of the fluorescent lamp, a configuration in which a thin metal plate is wound around the outside of the glass bulb 1 is adopted. In addition, in the process of forming the solder alloy fusion layer 5 in which 40% by weight of bismuth, 0.1% by weight of copper and the remainder of which is tin force are formed in the gap between the metal external electrode 22 and the glass bulb 1, Then, the end of the glass bulb 1 to which the outer electrode 22 is attached is immersed in the melt of the solder alloy and then pulled up, so that the solder alloy is fused to the gap between the inner surface of the outer electrode 22 and the outer surface of the glass nozzle 1. Layer 5 was formed.

A structure having the same structure as that of the example and provided with a solder alloy fusion layer containing tin as a main component without containing bismuth is referred to as Comparative Example 1.

[0063] Comparative Example 2 is a configuration in which a solder alloy fusion layer 5 having adhesiveness between the glass bulb 1 and the external electrode 22 in the embodiment is provided, and the outer side of both ends of the fluorescent lamp. In this configuration, only external electrodes are provided respectively. This configuration is the same as that of the external electrode disclosed in Japanese Patent Laid-Open No. 2003-91007 described above.

[0064] Comparative example 3 is configured without the external electrode 22 in the example. Comparative Example 3 has a structure in which a solder alloy fusion layer mainly composed of tin is provided outside the both ends of the glass bulb.

[0065] For each fluorescent lamp of Example, Comparative Example 1, Comparative Example 2 and Comparative Example 3, the peeling rate, the presence or absence of thermal shock damage during production, the presence or absence of pinholes in the external electrode, and the lamp current variation Table 1 shows the results of measuring the tack. Peeling rate is the ratio of peeling when a lkg diameter copper wire is joined to the target external electrode part and a 2Kgf bow tension is loaded in the glass tube axis direction (number of experiments: n = 20 Number). In addition, the presence or absence of pinholes was inspected by turning on the manufactured fluorescent lamp.

[0066] [Table 1] Peeling rate Pinhole during manufacturing Lamp current

Variation of thermal shock damage Example 0% 0.00% None ± 4% Comparative example 1 0% 0. 58% None ± 4% Comparative example 2 ― 0.00% None ± 1 1% Comparative example 3 60% 1. ± 5% with 73%

As is apparent from the results shown in Table 1, the fluorescent lamp of the present invention (Example) has a fluorescent lamp (Comparative Examples 1, 2, and 3) that lacks some of the structural requirements of the present invention. If the characteristics were excellent, it was a fluorescent lamp with excellent reliability without damage and pinholes due to thermal shock during manufacturing. In addition, according to the embodiment, since damage due to thermal shock during production does not occur, in addition to the direct effect of reducing the defective rate, sorting work for non-defective products and defective products becomes unnecessary and the inspection process is omitted. Can greatly contribute to the reduction of manufacturing costs. In addition, according to the external electrode type discharge lamp of the present invention, it becomes possible to improve the reliability of the pack light in the liquid crystal display device and to provide it at a low price, and the liquid crystal display device whose display screen will become larger in the future. It is suitable for being used.

Claims

The scope of the claims

[1] An envelope made of a glass material that forms a hollow hermetic space, a gas of a discharge medium enclosed in the envelope, and a gas of the discharge medium provided on the outer surface of the envelope An external electrode for causing a dielectric barrier discharge,

The external electrode is made of a conductive material plate, and is bonded by a solder alloy fusion layer provided around the outer surface of the envelope.

The solder alloy is an external electrode type discharge lamp in which bismuth is contained in an amount of 30 wt% to 70 wt%, and the balance is made of tin.

2. The external electrode type discharge lamp according to claim 1, wherein the external electrodes are provided at both ends of the cylindrical envelope.

[3] The external electrode type discharge lamp according to claim 1 or 2, wherein the solder alloy contains copper in an amount of 0.01 wt% to 2 wt% in addition to the bismuth and the tin.

4. The external electrode type discharge lamp according to claim 1, wherein the external electrode is covered with the solder alloy.

[5] An envelope made of glass material forming a hollow hermetic space, a gas of a discharge medium enclosed in the envelope, and a gas of the discharge medium provided on the outer surface of the envelope An external electrode for causing a dielectric barrier discharge, and the external electrode is made of a conductive material, and is formed by a solder alloy fusion layer provided around the outer surface of the envelope. The solder alloy is bonded to an external electrode type discharge lamp comprising bismuth in a range of 30% to 70% by weight and the balance being tin.

With a liquid crystal display board,

The liquid crystal display device, wherein the external electrode type discharge lamp is used as a backlight of the liquid crystal display panel.

6. The liquid crystal display device according to claim 5, wherein the external electrodes are respectively provided at both ends of the cylindrical envelope.

7. The liquid crystal display device according to claim 5, wherein the solder alloy contains copper in an amount of 0.01 wt% to 2 wt% in addition to the bismuth and the tin.

[8] The external electrode is covered with the solder alloy! 6. A liquid crystal display device according to claim 5 Place.

[9] An envelope made of a glass material that forms a hollow hermetic space, a gas of a discharge medium enclosed in the envelope, and a gas of the discharge medium provided on the outer surface of the envelope An external electrode for causing dielectric barrier discharge, and the external electrode is provided with a plate force of a conductive material and is provided around the outer surface of the envelope. The solder alloy is a method of manufacturing an external electrode type discharge lamp, wherein the solder alloy contains bismuth in a range of 30% to 70% by weight and the balance is tin.

A first step of attaching the external electrode to the envelope;

A method of manufacturing an external electrode type discharge lamp, comprising: a second step of forming the fusion layer by pouring the solder alloy between an outer surface of the envelope and an inner surface of the external electrode.

[10] In the second step, the fusion layer is formed between the envelope and the external electrode by immersing the external electrode attached to the envelope in the molten solder alloy. The method of manufacturing an external electrode type discharge lamp according to claim 9 to be formed.

11. The method for manufacturing an external electrode type discharge lamp according to claim 10, wherein in the second step, the external electrode is immersed while applying an ultrasonic wave to the solder alloy.

12. The external electrode type according to claim 9, wherein, in the second step, the solder alloy in which copper is added in a range of 0.01 wt% to 2 wt% in addition to the bismuth and the tin is used. Manufacturing method of discharge lamp.