JP2010080338A - Fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hot cathode fluorescent lamp in which the end part of a filament is connected to a lead wire with a required strength and with a simple structure, and of which tube diameter is 8 mm or less. <P>SOLUTION: The fluorescent lamp is equipped with: a thin and long bulb 1 of the tube diameter of 8 mm or less, wherein a phosphor layer is formed inside the surface of the bulb; a pair of hot cathode type electrode mounts 2 which includes a filament 2a of which the central part is curved and the both end parts are nearly in straight shape, a pair of lead wires 2b of which the top ends are inserted into the coil of the both end parts of the filament and a part of the insertion portion is welded to the filament to support the filament, and an emitter 2e which is supported to the portion excluding the both end parts of the filament, wherein the electrode mounts are arranged separated inside the bulb; and a discharge medium sealed inside the bulb. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fluorescent lamp having a small diameter and a hot cathode type.

  Currently, a cold cathode fluorescent lamp having a tube diameter of 3 to 4 mm is used as a backlight for a liquid crystal display. In general, cold cathode fluorescent lamps are known to have lower luminous efficiency and less total luminous flux than hot cathode fluorescent lamps. This is because the upper limit of the discharge current is about 10 mA due to the performance of the electrode.

  Recently, higher brightness and lower power consumption of liquid crystal displays have been developed. Accordingly, it is desired to develop a fluorescent lamp having a large lamp current upper limit, a high luminous efficiency, and a tube diameter equivalent to that of a cold cathode fluorescent lamp as a backlight light source.

  It is known that a hot cathode fluorescent lamp that has been widely used for general illumination has an advantage that the lamp current upper limit is larger and the luminous efficiency is higher than that of a cold cathode fluorescent lamp.

  When the electrode incorporated in the small-diameter bulb is replaced with a hot cathode type, an emitter is attached thereto using a filament. If the filament is made small enough to be compatible with a small-diameter bulb, the amount of deposited emitter will be reduced and the fluorescent lamp will have a short life. Therefore, when the filament is bent so that the required amount of emitter can be attached, the filament must be connected between the pair of lead wires with the required strength, and the connecting portion must not be enlarged. .

  Conventionally, both ends of a coil (filament) for a discharge lamp curved in a U-shape are sandwiched between sleeve-shaped contact plates, and the contact plate is partially melted and solidified to coincide with the lead wire in the axial direction. It is known to fix it (see Patent Document 1).

Japanese Patent Application Laid-Open No. 07-014542

  However, in the discharge lamp described in Patent Document 1, since the filament is connected to the lead wire using the contact plate, the structure is complicated, the connecting work is troublesome, and the connecting portion becomes large. When the inside of the bulb having a tube diameter of 8 mm or less is adapted, the filament length cannot be increased accordingly.

  An object of the present invention is to provide a hot-cathode fluorescent lamp having a tube diameter of 8 mm or less in which the end of the filament is connected to a lead wire with a required strength and a simple structure.

  The fluorescent lamp of the present invention includes an elongated bulb having a tube diameter of 8 mm or less having a phosphor layer formed on the inner surface side; a filament having a curved central portion and substantially straight ends on both ends, and coils in both ends of the filament A pair of lead wires that are welded to the filament at a part of the insertion part to support the filament, and an emitter supported at a part excluding both ends of the filament, and are separated from the inside of the bulb. And a pair of hot cathode electrode mounts; a discharge medium sealed in the bulb.

  According to the present invention, in the hot cathode electrode mount, the tip of the lead wire is inserted into the coil at both ends of the filament supported by the emitter, and the lead is welded to the filament at a part of the insertion portion. By connecting the wire and the filament, the support structure by the lead wire at the end of the filament is simplified, and the connecting portion is miniaturized. A long-life fluorescent lamp can be provided by increasing the size of the connecting portion.

  Further, in addition to the above, the cross-sectional shape of the coil wire in the welded portion with the filament lead wire is deformed into an elliptical shape and is recessed into the lead wire, so that the contact area between the lead wire and the filament is increased, which is favorable. An electrical connection is obtained and the filament can be supported mechanically and firmly.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  1 and 2 show an embodiment for carrying out the fluorescent lamp of the present invention. FIG. 1 is a cross-sectional view of the main part of the fluorescent lamp, and FIG. 2 is connected to a lead wire by bringing the end of the filament closer to the bead member. It is the enlarged front view and principal part expanded sectional view which show the connection part at the time of doing.

  In this embodiment, the fluorescent lamp includes a bulb 1, a hot cathode electrode mount 2, and a discharge medium.

  The bulb 1 is elongate and translucent, preferably transparent. The tube diameter is the outer diameter of the light emitting portion of the bulb 1, and both ends may be somewhat thicker due to sealing, or may be narrower. Further, the bulb 1 shown in FIG. 1 is flat at both end portions in a plane parallel to the drawing, and the width of the flat portion is slightly narrower than the light emitting portion.

  In the present invention, the tube diameter is not particularly limited as long as the tube diameter is 8 mm or less and the hot-cathode electrode mount 2 can be incorporated into the bulb 1. However, if the tube diameter is less than 3 mm, the difficulty in incorporating the hot cathode electrode mount 2 into the bulb 1 tends to increase. On the other hand, if the tube diameter exceeds 8 mm, it becomes too thick to meet the demand for thin backlight. The tube diameter is preferably 3 to 8 mm.

  In the present invention, the tube length can be appropriately selected according to the use of the fluorescent lamp, and is not particularly limited. However, several hundred to several hundreds of millimeters are suitable from the request of the main application. A preferred material for the bulb 1 is a glass bulb, and borosilicate glass is particularly suitable as the glass.

  Further, the bulb 1 can be formed in an airtight state by sealing both ends of the glass base tube having both ends opened. In this case, various known sealing structures can be appropriately selected and employed. In the illustrated form, the sealing portion 1b that can be evacuated by heating and melting the end portion of the glass base tube in a state where the exhaust pipe 1a is inserted at the center axis position in the end portion of the glass base tube and pinch sealing is provided. Forming. If desired, a bead sealing structure in which a bead member 2c, which will be described later, is sealed and sealed to the end of the glass base tube can also be employed.

  Note that both ends of the glass tube can have the same sealing structure as the above-described pinch seal. As a result, the exhaust pipe 1c can be sealed at both ends of the valve 1 at the time of sealing and exhausted from both ends and, if desired, from only one end. However, if desired, a pinch seal or other sealing structure that does not seal the exhaust pipe 1a can be adopted on the other end side. Moreover, the code | symbol 1a1 of FIG. 1 is the exhaust chip off part formed after sealing the exhaust pipe 1a.

Further, the bulb 1 has a phosphor layer 1c formed on the inner surface side. The phosphor layer 1c can be formed by an ordinary method using an appropriate phosphor, but a phosphor having a three-wavelength emission type is preferably used. Further, the phosphor layer 1c can be formed directly on the inner surface of the bulb 1, but is preferably formed on the inner surface of the bulb 1 through a protective film (not shown). Note that the protective film can be formed using a known material, for example, a metal oxide such as aluminum oxide Al ₂ O ₃ , Y ₂ O ₃ , CeO, ZnO, TiO ₂ , or SiO ₂ . In order to prevent the occurrence of exhaust failure, the phosphor layer 1c may be formed closer to the center of the lamp than the gap c of the bulb 1-bead member 2c.

  A pair of hot cathode electrode mounts 2 are arranged opposite to both end sides of the bulb 1, and each includes a filament 2a, a pair of lead wires 2b, 2b, and an emitter 2e, and at least the filament 2a is preferably disposed inside the bulb 1. Are sealed apart from each other at both ends. If desired, a bead member 2c and an anchor 2d can be added to the hot cathode electrode mount 2.

  The filament 2a is curved at the center and has substantially straight portions at both ends. The shape of the curve is not particularly limited. For example, it is U-shaped or semicircular. Since the bulb 1 has a small diameter of 8 mm or less, the degree of freedom with respect to the arrangement of the curved portion of the filament 2a in the bulb 1 is not great. For example, as shown in FIG. The pair of end portions 2a2 and 2a2 are substantially linear and can be supported by the pair of lead wires 2b and 2b. Since the center of the filament 2a is curved, the filament 2a can be lengthened. The adhesion amount of the emitter 2e can be increased according to the length of the filament 2a. In the case of FIG. 1, the filament 2 a has a convex shape toward the center in the length direction of the bulb 1. In the above arrangement, it is preferable that the center of the folded portion 2a1 is located substantially on the tube axis. Moreover, when the bead member 2c mentioned later is comprised, the width a of the filament 2a is preferably set so as to be within the line of sight of the bead member 2c.

  Further, the coil pitch of the filament 2a is preferably 150 to 350% at the attachment portion of the emitter 2e, 100 to 200% at the connection portion with the lead wire 2b at both ends, and smaller in coil pitch than the former. . As a result, the contact area between the lead wire 2b and the filament 2a can be increased to increase the welding strength, and the amount of attached emitter can be increased at the attached portion of the emitter 2e.

  Further, as shown in FIG. 2, in the curved portion of the filament 2a, the outer coil pitch interval D1 is larger than the inner coil pitch interval D2. As a result, the emitter holding force of the filament 2a is improved.

  Furthermore, the filament 2a may be either a single coil or a multiple coil in the present invention. Generally, it is preferable to select a single coil for miniaturization and a multiple coil such as a triple coil for long life.

  The pair of lead wires 2b and 2b supports the filament 2a connected to both ends thereof as shown in an enlarged view of the main part of the hot cathode electrode mount 2 in FIG. The mode of support is as follows. That is, the end 2a2 of the filament 2a and the axis of the lead wire 2b are aligned with each other, the tip of the lead wire 2b is inserted into the coil of the linear portion of the filament 2a, and the lead wire 2b and the filament 2a are partly inserted. And is supported by welding. In addition, a welding part is a circular part which gave the dotted line in FIG.

  As an aspect of the welding, as shown in the enlarged cross-sectional view of the main part in FIG. 2, the coil wire of the filament 2a is deformed into an ellipse at the welded portion between the lead wire 2b and the filament 2a. Further, as shown in the enlarged cross-sectional view of the main part of FIG. 2, the contact portion of the coil wire can be configured to be recessed from the surface of the lead wire 2b to the inside. In order to achieve such a configuration, for example, a lead wire 2b having a melting point lower than that of the filament 2a may be used, and resistance welding may be performed so as to sandwich the filament 2a from the outside. The lead wire 2b in the vicinity of the bead member 2 has an oxidized surface during the process of forming the bead member 2c, and the portion is a portion that is difficult to maintain electrical continuity with the filament 2a. It is desirable that the lead wire 2b is welded at a point separated from the bead member 2c by 1.0 mm or more.

  For the lead wire 2b, a metal having good sealing property with the valve 1 and / or a bead member 2c described later, such as Kovar, can be used. In this aspect, since the sealing property is good, the lead wire 2b can be directly sealed to the end of the bulb 1 and led out to the outside.

  Furthermore, the lead wire 2b is shaped by sharpening the tip portion of the lead wire 2b, rounding, or forming the taper portion connected to the flat portion with the tip portion being a substantially flat portion having a small diameter. Can be easily inserted into the end 2a2 of the filament 2a.

  Furthermore, if the flat portion is formed on the side surface of the portion of the lead wire 2b that is inserted into the end portion 2a2 of the filament 2a, and the end portion 2a2 of the filament 2a is welded to the flat portion, the lead wire 2b in the welding is obtained. And the end area 2a2 of the filament 2a can be increased, which contributes to the formation of a reliable connection. When forming the flat portion, the lead wire 2b is crushed to form a protruding portion on the side of the flat portion, and this protruding portion is used for temporarily fixing the end 2a2 of the filament 2a before welding. This improves the workability of the connection forming process.

  The bead member 2c is attached to the hot cathode electrode mount 2 as desired. The bead member 2c is formed by forming glass into a ball shape having an appropriate shape, for example, a substantially spherical shape, an elliptical spherical shape, and the like, and a desired pair of lead wires 2b, 2b are separated and sealed therein. Support at intervals. Therefore, the bead member 2c is sealed to the intermediate portion of the lead wire 2b.

  As shown in FIG. 2, the end portions 2a2 and 2a2 of the filament 2a inserted through the lead wires 2b and 2b may be brought into contact with the bead member 2c. Thereby, since the insertion length of the filament 2a can be managed to be a constant length, variations in the length b of the filament 2a can be suppressed. However, if the end portions 2a2 and 2a2 of the filament 2a are brought into contact with the bead member 2c, there is a concern that the heat of the filament 2a is transmitted to the bead member 2c and the bead member 2c is broken. Therefore, when the end portions 2a2 and 2a2 of the filament 2a are brought into contact with the bead member 2c, the protruding length g of the lead wires 2b and 2b is set to 1.5 mm or more, and the filament 2a is heated to about 800 ° C. during lighting. It is preferable to prevent the above problem from occurring by keeping the distance between the two and lowering the temperature of the contact portion. The upper limit of the protrusion length g is desirably 5 mm or less in order to shorten the invalid light emission length.

  Further, the length by which the lead wire 2d is sealed in the bead member 2d, that is, the sealing length is preferably 0.5 mm or more. Since the lead wire 2b is firmly supported as the sealing length increases, the strength of the portion of the lead wire 2b protruding from the bead member 2c increases. As a result, the filament 2a can be prevented from contacting the inner surface of the valve 1. Further, the heat of the filament 2a is transferred to the sealing portion of the bulb 1 to suppress the sealing portion temperature from increasing.

  Moreover, since the diameter of the bead member 2b is smaller than the inner surface of the valve 1, that is, the inner diameter, a gap c is formed between the bead member 2b and the inner surface of the valve 1. If the gap c (mm) satisfies 0.1 ≦ c ≦ 0.4, the hot cathode electrode mount 2 can be inserted into the valve 1 without difficulty, and the inside of the valve 1 can be exhausted through the gap c. It is. Here, the inner surface of the bulb 1 includes an adhesion layer such as the phosphor layer 1c, and the inner diameter is slightly smaller than the inner surface of the bulb 1 alone. However, when all or part of the adhesion layer such as the phosphor layer 1c is not present at the insertion position of the bead member 2c, the inner diameter is increased accordingly.

  Furthermore, the protruding length g of the lead wire 2b from the bead member 2c is a dimension including the tip portion inserted through the end 2a1 of the filament 2a, but the bead member 2c and both ends 2a2, 2a2 of the filament 2a Determine the distance between. For this reason, if the protrusion length g is too short, the heat generated by the filament 2a is conducted through the lead wire 2b and is easily absorbed by the bead member 2c having a large heat capacity, resulting in a temperature drop at both ends of the coil filament 2a. This is not preferable because temperature uniformity of 2a is hindered.

  The protrusion length g is preferably 1 mm or more. However, if the protrusion length g is too large, the coil filament 2a tends to swing undesirably, which is not preferable. The protrusion length g is preferably 5 mm or less. The protrusion length g is more preferably 1 to 2.5 mm.

  The anchor 2d is added to the hot cathode electrode mount 2 as desired. And the support part 2d1 of the front-end | tip supports the return part 2a1 of the filament 2a, for example, and the base end part is planted to the bead member 2c by glass welding. As a result, the folded portion 2a1 of the filament 2a is supported by the anchor 2d and both ends thereof are supported by the pair of lead wires 2b and 2b, so that the earthquake resistance and impact resistance are improved.

  Further, it is preferable to use an extremely fine heat-resistant metal wire in which the diameter of the anchor 2d is in the range of 0.05 to 0.3 mm in order to suppress the temperature drop of the support portion of the filament 2a. If the diameter is less than 0.05 mm, the mechanical strength as the anchor 2d is insufficient, which is not possible. On the other hand, if it exceeds 0.3 mm, the heat capacity becomes too large, and the temperature in the vicinity of the support portion by the anchor 2d of the folded portion 2a1 of the filament 2a is undesirably lowered.

  Furthermore, the anchor 2d is formed using a heat-resistant metal. As the heat-resistant metal, for example, a heat-resistant metal such as molybdenum Mo, tungsten W, rhenium-tungsten alloy Re-W can be used.

  The emitter 2e is a thermoelectron emitting material, and is attached to and supported by the filament 2a mainly on a curved semi-circular portion of the filament 2a as shown in FIG. The emitter 2e is heated when the temperature of the filament 2a rises, and starts thermionic emission. The emitter 2e is not limited in its material, but a known one can be used. For example, about 3.0 mg of a coating solution prepared by mixing barium carbonate, calcium carbonate, and strontium carbonate in a mass ratio of 4: 4: 2 is applied to the filament 2a, dried and energized and heated to turn the carbide into a metal. An emitter changed to oxide is generated and left in the filament 2a. The emitter 2e has a lead wire 2b in order to effectively remove impurities such as moisture from the emitter 2e in a heating process performed after the application of the coating liquid, so as not to affect the lamp characteristics. It is desirable to form in a region from a part about 1 mm away from the other part to the other same part.

  Further, as a preferred embodiment of the present invention, in addition to the above, the emitter 2e1 can be attached to the support portion 2d1 of the filament 2a of the anchor 2d and the vicinity thereof. As described above, in the embodiment in which the fine heat-resistant metal wire is used for the anchor 2d, the temperature at the support portion 2d1 of the coil filament 2a on the tip side rises to near the temperature of the coil filament 2a during lighting. Therefore, thermionic radiation can be emitted from the emitter 2e1 attached thereto, and the lifetime of the fluorescent lamp is increased accordingly. In the above aspect, the emitter anchor 2d may be attached to a portion other than the support portion 2d1 and the vicinity thereof. According to this embodiment, an average life extension of about 5% can be obtained as compared with the case where the emitter 2e1 is not attached to the anchor 2d.

  The discharge medium is enclosed in the bulb 1 and radiates ultraviolet rays by discharge generated between the pair of filaments 2a and 2a. As the discharge medium, it is preferable to use a rare gas such as neon, argon, xenon, or krypton or a mixed gas thereof and mercury.

  In the embodiment, the whole structure is shown in FIG. 1, and the manner of connecting filament leads and supporting the emitter is the structure shown in FIG.

Valve: BKU (borosilicate glass) manufactured by Nippon Electric Glass Co., Ltd., pipe diameter 4mm, inner diameter 3.0mm, total length 1200mm, exhaust pipe is outer diameter 2.0mm, inner diameter 1.4mm,
The phosphor layer is made of Y ₂ O ₃ : Eu ³⁺ , LaPO ₄ : Ce ³⁺ , Tb ³⁺ , BaMg ₂ Al ₁₀ O ₁₇ : Eu ²⁺
3-wavelength phosphor, film thickness 20μm
Filament: W, wire diameter 50μm, inner diameter 200μm, single coil,
The length b protruding from the lead wire is 5mm and the width a is 2mm.
Lead wire: Kovar, diameter 0.3mm, protrusion length g = 2mm
Anchor: Mo, diameter 0.15mm
Bead member: Borosilicate glass, almost spherical shape with a diameter of 2.7 mm Lead wire connection form: Lead wire protruding length from the bead member is 2 mm,
Lead wire insertion length to filament 2mm,
The weld was resistance welded at a position 1 mm away from the bead member.

  Emitter support: The emitter was supported from a position 1 mm away from the welding position to the tip of the curved portion.

Discharge medium: Ar40%, Ne60% (enclosure pressure 1330Pa), Hg about 3mg
Current: Lamp current 10-30mA, filament heating current about 500mA

Next, the preferable aspect at the time of lighting the fluorescent lamp of this invention is demonstrated. When the fluorescent lamp of the present invention is lit, it is preferable that a filament heating current is supplied separately from the lamp current to constantly heat the filament 2a. By this heating, the emitter 2e adhering to the filament 2a reaches about 800 ° C. even if a configuration in which an intermediate portion of the filament 2a is supported using an extremely fine (0.05 to 0.3 mm diameter) anchor is adopted. . In this state, thermionic emission is performed from most of the emitter 2e attached to the filament 2a.

  As a result, the current density on the surface of the electrode composed of the filament 2a and the emitter 2e is reduced, and the electrode life and thus the life of the fluorescent lamp is extended. In addition, a known circuit configuration can be used as appropriate for supplying a filament heating current separately from the lamp current.

Sectional section showing an embodiment for carrying out the fluorescent lamp of the present invention The enlarged front view and principal part expanded sectional view which show the connection part at the time of making the end part of a filament approach a bead member similarly, and connecting with a lead wire

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Valve | bulb, 1a ... Exhaust pipe, 1b ... Pinch seal part, 1c ... Phosphor layer, 2 ... Hot cathode type electrode mount, 2a ... Filament, 2a1 ... Folding part, 2a2 ... End part, 2b ... Lead wire, 2c ... Bead member, 2d ... anchor, 2d1 ... support part, 2e, 2e1 ... emitter

Claims (2)

An elongated bulb having a tube diameter of 8 mm or less having a phosphor layer formed on the inner surface side;
A pair of lead wires that are curved at the center and both ends are substantially linear, and are inserted into the coils at both ends of the filament, and welded to the filament at a part of the insertion portion to support the filament And a pair of hot cathode electrode mounts comprising an emitter supported on the filament and spaced apart within the bulb;
A discharge medium enclosed within the bulb;
A fluorescent lamp characterized by comprising:   2. The fluorescent lamp according to claim 1, wherein the filament is indented into the lead wire by deforming the cross-sectional shape of the coil wire into an elliptical shape at a welded portion with the lead wire.

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