GB2492854A - Cold cathode fluorescent lamp for illumination - Google Patents
Cold cathode fluorescent lamp for illumination Download PDFInfo
- Publication number
- GB2492854A GB2492854A GB1118607.9A GB201118607A GB2492854A GB 2492854 A GB2492854 A GB 2492854A GB 201118607 A GB201118607 A GB 201118607A GB 2492854 A GB2492854 A GB 2492854A
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- GB
- United Kingdom
- Prior art keywords
- coil
- wire coil
- helical wire
- emitter
- cold cathode
- Prior art date
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Links
- 238000005286 illumination Methods 0.000 title claims abstract description 27
- 239000011521 glass Substances 0.000 claims abstract description 37
- 239000010953 base metal Substances 0.000 claims abstract description 31
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims abstract description 29
- 229910052721 tungsten Inorganic materials 0.000 claims abstract description 29
- 239000010937 tungsten Substances 0.000 claims abstract description 29
- 229910001080 W alloy Inorganic materials 0.000 claims abstract description 14
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 claims abstract description 12
- 238000004804 winding Methods 0.000 claims abstract description 11
- KOPBYBDAPCDYFK-UHFFFAOYSA-N caesium oxide Chemical compound [O-2].[Cs+].[Cs+] KOPBYBDAPCDYFK-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910001942 caesium oxide Inorganic materials 0.000 claims abstract description 6
- UQYQVPOTZORXPY-UHFFFAOYSA-N calcium strontium oxygen(2-) Chemical compound [O-2].[Ca+2].[O-2].[Sr+2] UQYQVPOTZORXPY-UHFFFAOYSA-N 0.000 claims abstract description 6
- 230000001939 inductive effect Effects 0.000 claims abstract description 3
- 239000011248 coating agent Substances 0.000 claims description 5
- 238000000576 coating method Methods 0.000 claims description 5
- 239000000395 magnesium oxide Substances 0.000 claims description 5
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 5
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 5
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 claims description 5
- 239000000463 material Substances 0.000 abstract description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 4
- 239000002041 carbon nanotube Substances 0.000 abstract description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 abstract description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 16
- 238000004544 sputter deposition Methods 0.000 description 12
- 239000007789 gas Substances 0.000 description 8
- 230000001965 increasing effect Effects 0.000 description 7
- 229910000990 Ni alloy Inorganic materials 0.000 description 6
- 229910052759 nickel Inorganic materials 0.000 description 6
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 5
- 229910052753 mercury Inorganic materials 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 238000010304 firing Methods 0.000 description 4
- 230000000717 retained effect Effects 0.000 description 4
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
- 239000007924 injection Substances 0.000 description 2
- 229910000833 kovar Inorganic materials 0.000 description 2
- 239000004973 liquid crystal related substance Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 239000002071 nanotube Substances 0.000 description 1
- 229910052754 neon Inorganic materials 0.000 description 1
- GKAOGPIIYCISHV-UHFFFAOYSA-N neon atom Chemical compound [Ne] GKAOGPIIYCISHV-UHFFFAOYSA-N 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 229940056345 tums Drugs 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000003466 welding Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
- H01J61/76—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a filling of permanent gas or gases only
- H01J61/78—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a filling of permanent gas or gases only with cold cathode; with cathode heated only by discharge, e.g. high-tension lamp for advertising
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/04—Electrodes; Screens; Shields
- H01J61/06—Main electrodes
- H01J61/067—Main electrodes for low-pressure discharge lamps
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/04—Electrodes; Screens; Shields
- H01J61/06—Main electrodes
- H01J61/067—Main electrodes for low-pressure discharge lamps
- H01J61/0672—Main electrodes for low-pressure discharge lamps characterised by the construction of the electrode
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/04—Electrodes; Screens; Shields
- H01J61/06—Main electrodes
- H01J61/067—Main electrodes for low-pressure discharge lamps
- H01J61/0675—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/04—Electrodes; Screens; Shields
- H01J61/06—Main electrodes
- H01J61/067—Main electrodes for low-pressure discharge lamps
- H01J61/0675—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode
- H01J61/0677—Main electrodes for low-pressure discharge lamps characterised by the material of the electrode characterised by the electron emissive material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/30—Vessels; Containers
Landscapes
- Discharge Lamp (AREA)
- Vessels And Coating Films For Discharge Lamps (AREA)
- Discharge Lamps And Accessories Thereof (AREA)
- Light Sources And Details Of Projection-Printing Devices (AREA)
Abstract
Provided is a cold cathode fluorescent lamp (CCFL) that can be used as an illumination light source. The CCFL includes a cold cathode electrode disposed at each end of a glass tube, a fluorescent layer being formed on an inner surface of the glass tube 17. Each of the cold cathode electrodes includes a base metal 7 connected to the front ends of lead wires 9a, 9b for connection with a power source. A helical wire coil 3 is formed by helically winding a tungsten or tungsten-alloy wire around a cup shape (Fig. 1), the helical wire coil 3 being connected to the base metal 7 in a manner such that the helical wire coil 3 is erected in a length direction of the glass tube. An emitter coated coil is inserted in the helical wire coil about the end of the coil and is coated with an emitter material such as cesium oxide, barium oxide, strontium calcium oxide, carbon nanotubes etc for inducing emission of electrons.
Description
COLD CATHODE FLUORESCENT LAMP FOR ILLUMINATION
BACKGROUND
[0001] The present disclosure herein relates to a cold cathode fluorescent lamp (CCFL) for illumination, and more particularly, to a highly efficient, long-lifespan CCFL improved in tube current, optical efficiency, brightness, and lifespan for being used as an illumination light source in addition to conventional use as a backlight of a liquid crystal display, a scanning light source of a facsimile, an eraser lamp of a copier, etc. [0002] In the related art, cold cathode fluorescent lamps (CCFL5) are used as light sources such as backlights of liquid crystal displays, scanning light sources of facsimiles, and eraser lamps of copiers, and necessary brightness levels for such devices can be obtained by applying onLy a tube current of about 4 to 4 mA to the CCLFS. Such a CCFL includes cup-shaped electrodes provided at both ends of a glass tube, and a fluorescent layer formed by applying a fluorescent material to the inner surface of the glass tube. Rare gas such as neon gas, argon gas, and xcnon gas is tiLled in the glass tube together with a small amount of mercury, and the glass tube is sealed. If a high voltage is applied to the cup-shaped electrodes provided at both sides of the glass tube, a small number of electrons ionize the rare gas sealed in the glass tube, and secondary electrons are emitted from the cup-shaped electrodes as the ionized rare gas collide with the cup-shaped electrodes (this is called a glow discharge). The secondary electrons collide with the mercury, and as a result, the mercury emits ultraviolet rays toward the fluorescent layer formed on the inner surface of the glass tube. Then, the fluorescent material of the fluorescent layer emits visible light. At this time, a tube current of about 4 mA to 5 mA flows in the glass tube. However, a tube current of 10 mA or higher is necessary to increase the brightness of the CCFL to a level necessary for illumination.
[0003] In the related art, electrodes of a CCFL are formed into a cup shape to increase inner areas of the electrodes necessary for electron emission. In addition, such electrodes are mainly formed of nickel (Ni) because nickel (Ni) has a relative low melting point and can be easily machined into a desired shape such as a cup shape. However, nickel (Ni) or nickel alloys have high work functions and high sputtering coefficients. For this reason, cup-shape electrodes arc formed of an Nb-Ni alloy or Y-Ni alloy for increasing the sputtering resistance of the cup-shaped electrodes. However, the lifespan of such cup-shaped electrodes is short due to sputtering if a tube current of 10 mA or higher is applied to the electrodes.
Sputtering causes excessive heat generation at electrodes and largely decreases luminous efficacy. In addition, since a sputtering layer is formed on an inner surface 1 5 of a glass tube due to sputtering, it is difficult to obtain a brightness level necessary for illumination if electrodes are sputtered. That is, electrodes formed of nickel (Ni) or a nickel alloy are not suitable for a CCFL having a tube current of 5 mA or higher, and thus it is difficult to use a CCFL including cup-shaped nickel or nickel-alloy electrodes as an illumination light source.
[0004] Furthermore, in the related, since electrodes having large area are preferred, the sizes of the electrodes are excessively increased. Large electrodes occupy large spaces in glass tubes, and thus spaces for positive columns are reduced to decrease luminous efficacy and energy efficiency. Therefore, it is difficult to use CCFLs as illumination light sources.
STUJYIMARY
[0005] The present inyention is proposed to obviate the above-mentioned limitations arising when using a cold cathode fluorescent lamp (CCFL) as an illumination light source. For this, an object of the present invention is to provide an illumination CCFL including cold cathode electrodes that can be easily formed into a cup shape by using tungsten or a tungsten alloy having a low sputtering coefficient and a low work function.
[0006] Another object of the present invention to provide an illumination CCFL including short electrodes but capable of emitting very bright light.
[0007] Another object of the present invention is to provide an illumination CCFL on which two lead wires can be easily installed for compatibility with a socket for a typical hot cathode fluorescent lamp.
[0008] Another object of the present invention to provide an illumination 1 5 CCFL requiring a low discharge sustaining voltage so that the lifespan of electrodes can be increased.
(00091 Another object of the present invention is to provide an illumination CCFL having a structure on which an emitter can be easily coated and retained.
[0010] Embodiments of the present invention provide a CCFL for illumination, the CCFL including cold cathode electrodes, wherein each of the cold cathode electrodes include: a base metal connected to front ends of lead wires for coimection with a power source; a helical wire coil formed by helically winding a tungsten or tungsten-alloy wire around a cup shape, the helical wire coil being connected to the base metal in a manner such that the helical wire coil is erected in a length direction of the glass tube; and an emitter-coated coil inserted in the helical wire coil and coatcd with an emitter for inducing emission of electrons.
[0011] In some embodiments, the lead wires connected to the base metal may be two in number and may be electrically disconnected from each other at the base metal.
[0012] In other embodiments, the emitter-coated coil may be formed by forming a tungsten thin wire thinner than the helical wire coil and coating the thin wire with at least one emitter selected from cesium oxide, barium oxide, strontium calcium oxide, yttrium oxide, and magnesium oxide.
[0013] In still other embodiments, the emitter-coated coil may be formed by winding a tungsten thin wire thinner than the helical wire coil into a thin coil, winding the thin coil into a helical shape, and coating the thin coil with at least one emitter selected from cesium oxide, barium oxide, strontium calcium oxide, yttrium oxide, and magnesium oxide.
BRIEF DESCRIPTION OF THE DRAWINGS
(00141 The accompanying drawings are included to provide a further understanding of the inventive concept, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the inventive concept and, together with the description, serve to explain principles of the inventive concept. In the drawings: [0015] FIG. I is a perspective view illustrating an emitter-coated coil according to the present invention; [0016] FIG. 2 is an exploded perspective view illustrating a cold cathode electrode according to the present invention; [0017] FIG. 3 is a perspective view illustrating the cold cathode electrode according to the present invention; [0018] FIG. 4 is a partial perspective view illustrating the cold cathode electrode sealed in a glass tube according to the present invention; and [0019] FIG. 5 is a partial sectional view illustrating a cold cathode fluorescent lamp (CCFL) for illumination according to the present invention.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0020] Hereinafter, exemplary embodiments will be described in more detail with reference to the accompanying drawings.
[0021] Referring to FIGS. 4 and 5, a cold cathode fluorescent lamp (CCFL) is provided for using as an illumination lamp. The CCFL includes a pair of cold cathode electrodes 1 disposed at both ends of a glass tube 17, and the inner surface of the glass tube 17 is coated with a fluorescent layer. The cold cathode electrodes 1 1 5 have a low sputtering coefficient, a low firing voltage, and a low discharge sustaining voltage, but can emit a large amount of electrons. In the CCFL, the fluorescent layer is formed on the inner surface of the glass tube 17 by using a fluorescent material, and the cold cathode electrodes I are disposed at both ends of the glass tube 17 to face each other. If a high voltage is alternately applied to the cold cathode electrodes 1, electrons are emitted from the cold cathode electrodes 1. The cold cathode electrodes I of the present invention have satisfactory resistance against sputtering, a low discharge firing voltage, and a low discharge sustaining voltage so that a tube current can be increased to 10 mA or higher for emitting a large amount of electrons for the purpose of illumination. Therefore, the CCFL of the present invention can be used as an illumination light source.
[0022] An emitter-coated coil 21 which is characteristic element of the present invention will now be described with reference to FIG. 1.
[0023] As shown in FIG. I, the emitter-coated coil 21 of the present invention has an appropriate structure for applying a powder emitter 5 to the emitter-coated coil 21 and retainitig the applied emitter 5. According an exemplary embodiment shown in FIG. 1, a thin wire coil 19 is formed of a tungsten thin wire (for example, having a diameter of 0.02 mm to 0.05 mm) which is thinner than a helical wire coil 3 (refer to FIG. 2) disposed around the emitter-coated coil 21, and then the thin wire coil 19 is wound in a helical shape to form the emitter-coated coil 21. The emitter 5 includes at least one of cesium oxide, barium oxide, strontium calcium oxide, yttrium oxide, and magnesium oxide in the form of powder. In the present invention, the eniittcr 5 is formed of a material having a low work thnction for easily emitting electrons. As a material has a low work function, the material can easily emit electrons. That is, the material can be easily discharged. Carbon 1 5 nanotubes may be used to easily apply the emitter 5. In this case, a coating material may be prepared by dispersing carbon nanotubcs in water and isopropyl alcohol while facilitating dispersion of the carbon nanotubes with sodium dodecylbeuzenesulfonate (a surfactant). Owing to the above-described structure of the emitter-coated coil 21, the total length of the emitter-coated coil 21 can be increased as compared with the size of the emitter-coated coil 21, and thus electrons can be emitted in a small space to cause a tube current of 1 0 mA or higher. In addition, it may be easy to densely apply the emitter 5 to gaps among closely stacked tums of a thin wire of the thin wire coil 19. Furthermore, the emitter S can be stably retained on the thin wire coil 19 for a long time, and thus the lifespan of the cold cathode electrodes 1 can be increased.
[0024] The emitter-coated coil 21 may be formed by winding a tungsten or tungsten-alloy linear thin wire (for example, having a diameter of 0.02 mm to 0.05 mm) thinner than the helical wire coil 3 instead of forming the emitter-coated coil 21 using the thin wire coil 19. The thin wire may be coated with an emitter including at least one of cesium oxide, barium oxide, strontium calcium oxide, yttrium oxide, and magnesium oxide. In the case, however, it may be difficult to coat the thin wire with the emitter and the emitter may not be retained for a long time as compared with the case of using the thin wire coil 19.
[0025] FIGS. 2 and 3 illustrate the helical wire coil 3 which is another characteristic element of the present invention. The helical wire coil 3 is formed by helically winding a tungsten or tungsten-alloy wire (having a diameter of 0.2 mm to 0.5 mm) around a cup shapc. The helical wire coil 3 is connected to a base metal 7 in a manner such that the helical wire coil 3 is erected in the length direction of the glass tube 17. In each of thc cold cathode electrodes 1 of the present invention, the base metal 7 is coupled to lead wires 9a and 9b connected to a powcr source. Dumet wires or Kovar wircs arc used as the lead wircs 9a and 9b. The lead wires 9a and 9b are perpendicular to the base metal 7. The helical wire coil 3 is erected on the base metal 7 in a direction opposite to the lead wires 9a and 9b. In the present invention, owing to the base metal 7, two lead wires can be used. Therefore, a typical fluorescent lamp socket can be used with the CCFL of the present invention. Both ends of the helical wire coil 3 are firmly fixed to the base metal 7 so that the helical wire coil 3 can be erected in the length direction of the glass tube 17, and the lead wires 9a and 9b (Dumet or Kovar wires) can be easily connected to the helical wire coil 3 through the base metal 7. Therefore, the base metal 7 is made of a material that can be welded to both the helical wire coil 3 and the lead wires 9a and 9b. The base metal 7 may have a rod or bead shape. If the base metal 7 is made of tungsten or a tungsten alloy, the base metal 7 may not be welded to the helical wire coil 3 made of tungsten or a tungsten alloy due to the high melting point of tungsten.
Therefore, the base metal 7 may be made of nickel or an nickel alloy. The helical wire coil 3 is electrically connected to a side of the base metal 7 by spot welding.
The two lead wires 9a and 9b are connected to the base metal 7 in a state where the lead wires 9a and 9b are electrically disconnected from each other. The lead wires 9a and 9b extend in a direction opposite to the helical wire coil 3 and are connected to an external power source.
[0026] As shown in FIG. 2, both ends of the helical wire coil 3 may extend toward the base metal 7 in a manner such that one of both ends of the helical wire coil 3 extends from the topside of the helical wire coil 3 toward the base metal 7 through the helical wire coil 3, and the emitter-coated coil 21 may be inserted in the helical wire coil 3 around the end of the helical wire coil 3. In this case, the emitter-coated coil 21 may not be separated from the helical wire coil 3. An end of the emitter-coated coil 21 may be welded to thc base metal 7 or not welded to the base metal 7. Referring to FIGS. 2 and 3, one emitter-coated coil 21 is disposed in the helical wire coil 3. However, another emitter-coated coil may be disposed in the emitter-coated coil 21, or two or more emitter-coated coils may be are closely arranged in the helical wire coil 3. Therefore, the cold cathode electrodes I can emit a large amount of electrons although a low voltage is applied to the cold cathode electrodes 1, and thus a brightness level necessary for illumination can be obtained without reducing the size of a positive column.
[0027] As shown in FIG. 3 and 4, the lead wires 9a and 9b are coupled to a glass stem 11 by a glass beading method, and the glass stem 11 is coupled to the glass tube 17. In the glass beading method, the lead wires 9a and 9b of the cold cathode electrode 1, and a gas injection conduit 15 are inserted in the glass stem 11, and an upper part of the glass stem 1] is melted to lix the lead wires 9a and 9b and the gas injection conduit 15. After the glass beading method is performed, glass beads remain at coupled portions. In this way, gaps between the glass tube 17 and the lead wires 9a and 9b of the cold cathode electrode 1 can be easily sealed.
[0028] It is difficult to make a cup-shaped electrode by using tungsten or a tungsten alloy because tungsten or tungsten alloys are not easily machined into desired shapes through a plastic working process. However, it is easy to make 1 0 tungsten or tungsten-alloy wires through a drawing process and wind the tungsten or tungsten-alloy wires into coils. A cup-shaped electrode having a low sputtering coefficient and a low work function can be made by stacking such coils having different diameters in multiple stages. The present invention is proposed based on this.
[0029] That is, according to the present invention, since the helical wire coil 3 is formed of tungsten or a tungsten alloy having a low sputtering coefficient and a low work function, the lifespan of the CCFL can be increased, and a discharge can be initiated with a low firing vohage. In addition, since the emitter-coated coil 2] is disposed in the helical wire coil 3, a discharge (electron emission) level necessary for illumination (10 mA or more) can be maintained with a low voltage in a stead state after the initial firing.
[0030] As shown in FIGS. 4 and 5, if a voltage is alternately applied to the cold cathode electrodes] of the CCFL, electrons are emitted from the cold cathode electrodes 1 by an electric field formed by the voltage. That is, since electrons arc emitted by an electric field, heat is not necessary for electron emission. Initially, a small amount of electrons remaining in the glass tube 17 collide with the cold cathode electrodcs 1, and thcn electrons arc emitted from the cold cathodc clectrodes 1. The electrons emitted from thc cold cathode electrodes I collide again with thc cold cathodc clcctrodes 1. In this way, the discharge (electron emission) continues.
During thc discharge, electrons moving to an anode collidc with the mercury filled in thc glass tube 17, and thcn ultraviolet rays arc emitted from the mercury toward the fluorescent layer of the glass tube 17. Then, the fluorescent layer is optically excited and emits visible light. Since electrons can be easily emitted in the CCFL of the prescnt invention, the CCFL can have high brightness and a long lifespan. In the present invention, the cold cathode electrodes I are formed of tungsten (W) having a high melting point as compared with a work flinction. Since it is difficult to machine tungsten (W), thc cold cathode electrodes 1 are formed by drawing tungsten wires and winding the tungsten wires into helical coils. Electrons can be emitted from the helical coils. As described above, if an electrode is constituted by a densely wound 1 5 helical tungsten coil having a sufficiently largc diameter and an emitter-coated coil disposed in the coil, the electrode can have an electron emission area greater than that of a corresponding cup-shaped electrode. In an illumination lamp, energy of 10 eV or higher is necessary for electrons colliding with an electrode. Therefore, it may be necessary to form electrodes of an illumination CCFL by using tungsten (W). In addition, the electrode may be formcd into a helical shape to increase an electron emission area of the clectrode. However, although the tungsten electrode has a helical shape, the electrode may require a high discharge sustaining voltage and may emit a small amount of electrons. Thus, the electrode may not be used in an illumination device. However, according to the present invention, a helical wire coil is formed of tungsten, and an emitter-coated coil is disposed in the helical wire coil, so that a tube current of 10 mA or higher necessary for illumination can be obtained while keeping a discharge sustaining voltage at a low level.
[0031] As described above, according to the present invention, since the electrodes of the CCFL are formed of tungsten or a tungsten alloy and have a double-coil structure, the electrodes can have a high sputtering resistance even when a tube current is 10 mA or higher, and the CCFL can emit very bright light owning to a low work function of tungsten. In addition, the electrodes can emit a sufficient amount of electrons although the electrodes have short lengths. Furthermore, since the base metal is disposed between the helical wire coil and the lead wires, the lead wires can be easily installed for compatibility with a socket for a typical hot cathode fluorescent lamp. Furthermore, since the emitter-coated coil is used as an inner coil, secondary electrons can be emitted at a low voltage, and thus a discharge sustaining voltage can be reduced to increase the lifespan of the electrodes. Furthermore, since the inner coil is formed by winding a tungsten thin coil into a helical shape and 1 5 coating the helically wound thin coil with an emitter, the emitter can be easily coated and stably retained on the inner coil.
Claims (1)
- <claim-text>WHAT IS CLAIMED IS: 1. A cold cathode fluorescent lamp (CCFL) for illumination, comprising cold cathode electrodes disposed at both ends of a glass tube, a fluorescent layer being formed on an inner surface of the glass tube, wherein each of the cold cathode electrodes comprise: a base metal connected to front ends of lead wires for conncction with a power source; a helica' wire coil formed by hehcally winding a tungsten or tungsten-alloy wire around a cup shape, the helical wire coil being connected to the base metal in a manner such that the helical wire coil is erected in a length direction of the glass tube; and an emitter-coated coil inserted in the helical wire coil and coated with an emitter for inducing emission of electrons.</claim-text> <claim-text>2. The CCFL of claim 1, wherein the lead wires connected to the base metal are two in number and are electrically disconnected from each other at the base metal.</claim-text> <claim-text>3. The CCFL of claim 1, wherein both ends of the helical wire coil extend toward the base metal in a manner such that an end of both ends of the helical wire coil extends from a topside of the helical wire coil toward the base metal through the helical wire coil, wherein the emitter-coated coil is disposed around the end of the helical wire coil.</claim-text> <claim-text>4. The CCFL of claim I, wherein the emitter-coated coil is formed by winding a tungsten thin wire thinner than the helical wire coil into a thin coil, winding the thin coil into a helical shape, and coating the thin coil with at least one emitter selected from cesium oxide, barium oxide, strontium calcium oxide, yttrium oxide, and magnesium oxide.</claim-text>
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR1020110069236A KR101206681B1 (en) | 2011-07-13 | 2011-07-13 | Cold cathode fluorescent lamp of high efficiency and long life for illumination |
Publications (2)
Publication Number | Publication Date |
---|---|
GB201118607D0 GB201118607D0 (en) | 2011-12-07 |
GB2492854A true GB2492854A (en) | 2013-01-16 |
Family
ID=45373539
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB1118607.9A Withdrawn GB2492854A (en) | 2011-07-13 | 2011-10-27 | Cold cathode fluorescent lamp for illumination |
Country Status (25)
Country | Link |
---|---|
JP (1) | JP5342627B2 (en) |
KR (1) | KR101206681B1 (en) |
CN (1) | CN102427016A (en) |
AR (1) | AR083680A1 (en) |
AT (1) | AT511690A1 (en) |
AU (1) | AU2011244900A1 (en) |
BR (1) | BRPI1106641A2 (en) |
CA (1) | CA2756496A1 (en) |
CH (1) | CH705270B1 (en) |
DE (1) | DE102011085328A1 (en) |
ES (1) | ES2402160B1 (en) |
FR (1) | FR2977973A1 (en) |
GB (1) | GB2492854A (en) |
GR (1) | GR1007827B (en) |
IL (1) | IL216064A0 (en) |
IT (1) | ITMI20112009A1 (en) |
MX (1) | MX2011011924A (en) |
NL (1) | NL2007664C2 (en) |
NZ (1) | NZ596039A (en) |
PL (1) | PL396924A1 (en) |
RU (1) | RU2486627C1 (en) |
SG (1) | SG187301A1 (en) |
TR (1) | TR201111032A1 (en) |
TW (1) | TW201303957A (en) |
ZA (1) | ZA201107898B (en) |
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US12020921B2 (en) | 2021-12-30 | 2024-06-25 | Awexome Ray, Inc. | Ultraviolet ray emitting device |
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Also Published As
Publication number | Publication date |
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DE102011085328A1 (en) | 2013-01-17 |
TW201303957A (en) | 2013-01-16 |
GB201118607D0 (en) | 2011-12-07 |
NL2007664C2 (en) | 2013-01-15 |
GR1007827B (en) | 2013-02-08 |
AU2011244900A1 (en) | 2013-01-31 |
JP5342627B2 (en) | 2013-11-13 |
MX2011011924A (en) | 2013-01-24 |
BRPI1106641A2 (en) | 2014-02-11 |
CH705270B1 (en) | 2013-04-30 |
ES2402160R1 (en) | 2013-11-04 |
ES2402160A2 (en) | 2013-04-29 |
CA2756496A1 (en) | 2013-01-13 |
FR2977973A1 (en) | 2013-01-18 |
CN102427016A (en) | 2012-04-25 |
NZ596039A (en) | 2013-05-31 |
AR083680A1 (en) | 2013-03-13 |
AT511690A1 (en) | 2013-01-15 |
CH705270A2 (en) | 2013-01-15 |
RU2486627C1 (en) | 2013-06-27 |
PL396924A1 (en) | 2013-01-21 |
ITMI20112009A1 (en) | 2013-01-14 |
ES2402160B1 (en) | 2014-08-27 |
IL216064A0 (en) | 2012-02-29 |
RU2011145580A (en) | 2013-05-20 |
KR101206681B1 (en) | 2012-12-03 |
ZA201107898B (en) | 2012-07-25 |
JP2013020927A (en) | 2013-01-31 |
SG187301A1 (en) | 2013-02-28 |
TR201111032A1 (en) | 2013-01-21 |
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