JP2008235152A - Electrode coil for hot-cathode type discharge lamp, hot-cathode type discharge lamp and lighting system using this electrode coil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the mechanical strength of a winding structure of a lead part of an electrode coil. <P>SOLUTION: The lead part of the electrode coil is formed such that a primary coil wire is folded back by two times and that the primary coil wire having a singular close contact winding part formed by two primary coil wires 21 and 23 densely wound at a predetermined pitch in the same winding direction, and a double winding part formed by the primary coil wires 21 and 23 densely wound at the predetermined pitch and a primary coil wire 22 wound rougher than at the predetermined pitch. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrode coil for a hot cathode discharge lamp used in an illumination device for a liquid crystal display, and a hot cathode discharge lamp and an illumination device using the same.

  Discharge lamps using phosphors as light emitters for light sources are used in a wide range of fields. Among the discharge lamps, a hot cathode type discharge lamp has high luminous efficiency and high luminance, and thus is used for general illumination and also as a backlight for liquid crystal displays.

  FIG. 1 is a cross-sectional view of a hot cathode discharge lamp used for conventional illumination. The hot cathode discharge lamp includes electrodes 4 at both ends of a glass tube, and a rare gas such as argon and mercury are sealed in the space of the glass tube 2 and a phosphor 8 is applied to the inner wall of the glass tube 2 ( For example, Patent Document 1).

  The electrode 4 includes a heater 6 having a coil portion 5. An electron emitting material 7 such as barium oxide is applied to the heater 6. The heater 6 is stretched by applying tension between the two lead wires 3 a and 3 b welded to the end of the glass tube 2. From these structures, the electrode 4 is arranged in a horizontal direction in which the coil portion 5 of the heater 6 is orthogonal to the tube axis of the glass tube.

  The light emission principle of such a hot cathode type discharge lamp 1 is as follows. When the electrodes 4 at both ends are energized and the electron emitting material 7 is heated by the heater 6 and a high frequency voltage is applied between the electrodes 4, electrons are emitted from the electron emitting material 7 and a glow discharge is generated between the electrodes 4. . The accelerated electrons emitted from the electron emitting material 7 collide with mercury atoms, and the mercury atoms emit ultraviolet rays. The ultraviolet light is converted into visible light by the phosphor 8, and the discharge lamp emits light.

  When a hot cathode type discharge lamp is used for a liquid crystal display backlight or the like, the heater is arranged in a direction orthogonal to the tube axis, so that there is a problem that a small diameter discharge lamp having an outer diameter of 4 mmφ or less cannot be configured. there were. Therefore, an electrode coil designed so that the heater is parallel to the tube axis has been devised, and a hot cathode discharge lamp with a glass tube outer diameter of 4 mmφ or less used for a liquid crystal display has been proposed (for example, Patent Document 2). ).

  FIG. 2 is a diagram showing a configuration in which the heater is arranged in parallel to the tube axis. A first lead 10 a and a second lead 10 b extend from the rear end side of the electrode coil portion, and a heater 9 is formed. The coil heater 9 is coated with an electron emitting substance 12. The electrode coil is disposed in a glass tube in which a gas containing a luminescent material is sealed and a phosphor is applied on the inner surface. Moreover, as for the electrode coil, the coil part is arrange | positioned in the vertical direction along the tube axis of a glass tube. A first lead 3a and a second lead 3b provided at both ends of the glass tube are welded to the electrode coil. Thus, since an electrode coil is arrange | positioned along the tube axis | shaft of a glass tube, a glass tube can be made thin, without shortening the length of a coil part.

  By reducing the diameter of the glass tube, the luminance can be improved, and the coil portion can be secured with a length that allows a sufficient amount of the electron-emitting material to be applied. Furthermore, ion sputtering can be further suppressed by disposing the anti-scattering member 11 around the electrode coil.

JP-A-5-251042 Japanese Patent Laid-Open No. 2005-235749

  Incidentally, a triple wound helical coil is suitable as the electrode coil shown in FIG. The triple-winding helical coil can hold the electron-emitting material more firmly than the double-helical coil-wound, and the electron-emitting material is less likely to fall off and has high reliability. However, the electrode coil arranged in the vertical direction along the tube axis has a drawback that it is deformed by mechanical vibration and thermal strain during heating. Since the support point of the electrode coil is a welding point between the leads 3a and 3b and the electrode coil legs 10a and 10b, the strength of the electrode coil legs is important for holding the electrode coil.

  In the electrode coil arranged in the vertical direction, it is necessary to secure a certain amount of the electron emitting material applied in order to increase the thermal efficiency and extend the life. Therefore, the length from the coil apex to the lead welded portion is required to be at least about 3 mm to 6 mm.

  The triple helical coil having such a length has a weak mechanical strength at the lead portion in the conventional winding method, and it is desired to be strengthened so as to be strong against mechanical vibration as an electrode coil for a hot cathode discharge lamp.

  In practice, in order to mechanically reinforce the lead portion of the electrode coil, one method is to make the primary coil wire of that portion an ideal tight winding. However, it is difficult to realize such close winding of an ideal primary coil wire due to variation in the diameter of the coil wire and springback, and sufficient mechanical strength cannot be obtained.

  Further, by making the lead part tightly wound, the electrical resistance of the lead part is lowered, and the effective heat generation amount of the main coil part which is supposed to generate heat can be increased. Thereby, it is desired to realize power saving for the entire heater.

  In view of the above-described conventional problems, the present invention provides an electrode coil for a hot cathode discharge lamp used in a lighting device for a liquid crystal display and the like that can solve at least one of the above problems, and a hot cathode discharge lamp and an illumination using the same. An object is to provide an apparatus.

  One aspect of the present invention is configured by a primary coil wire including a core wire that forms an electrode coil main portion and a winding wound around the core wire, and the primary coil wire is wound twice back and forth. A single tightly wound portion formed by two closely wound primary coil wires in the same winding direction and at a predetermined pitch; a primary coil wire closely wound at the predetermined pitch; An electrode coil for a hot-cathode discharge lamp, comprising a composite winding portion composed of a double winding portion formed by a primary coil wire wound more coarsely than the pitch of. The double winding portion is formed on the lead portion of the electrode coil for the hot cathode discharge lamp.

  Here, the double primary winding is formed by the first primary coil wire that is densely wound at the predetermined pitch and the second primary coil wire that is folded back and coarsely wound around the predetermined pitch. A third primary coil wire wound from the outside of the double winding portion with the same winding direction and the same pitch as that of the first primary coil wire; It is preferable that the single tightly wound portion is composed of a primary coil wire.

  Moreover, it is preferable that the first primary coil wire and the third primary coil wire are entangled with each other in the single-contact winding portion.

  Moreover, it is preferable that the winding pitch of the second primary coil wire is 9 times or more the predetermined pitch. The predetermined pitch is preferably about twice the outer diameter of the primary coil wire.

  The electrode coil for a hot cathode type discharge lamp of the present invention can be used as an electrode for a hot cathode type discharge lamp for a liquid crystal display. Moreover, the electrode coil for hot cathode discharge lamps of the present invention can be used as an electrode for an illumination device for a liquid crystal display.

  According to the present invention, since the winding structure of the lead portion is entangled and becomes dense, the mechanical strength is enhanced. In addition, since the coil wires are in close contact with each other, the electrical resistance is reduced and the heating efficiency can be improved.

  A method of winding the electrode coil in the embodiment of the present invention will be described below. In the present embodiment, a triple-winding helical coil is formed using a tungsten wire and a molybdenum wire. However, the present embodiment is characterized in that the winding is performed at the lead portion of the electrode coil.

  In the first step, a core wire is formed. A first molybdenum wire having a diameter of 10 to 50 μmφ is wound around a first molybdenum wire having the same diameter as that of the tungsten wire at a predetermined pitch to form a stranded wire to be a core wire. The predetermined pitch is preferably 100 μm to 1000 μm, more preferably 300 μm to 500 μm, and even more preferably about 500 μm.

  The molybdenum wire is melted by an etching process described later. The molybdenum wire is used as a spacer for providing a gap between the primary coil wire formed in the next step and the tungsten wire serving as the core wire.

  In the second step, a primary coil wire is formed. A primary coil wire is formed by winding a second tungsten wire having a diameter smaller than that of the first tungsten wire around the core wire formed in the first step at a predetermined pitch. The predetermined pitch is set to be narrower than at least the predetermined pitch in the first step. Specifically, the predetermined pitch is preferably 10 μm to 50 μm, and more preferably 20 μm.

  In the third step, a secondary coil wire is formed. The primary coil wire formed in the second step is wound around the second molybdenum wire at a predetermined pitch to form a secondary coil wire that is a coil having a larger structure. The diameter of the second molybdenum wire is preferably larger than the winding pitch of the primary coil wire. Specifically, the diameter of the second molybdenum wire is preferably 50 μm to 200 μm, and more preferably 100 μm. The predetermined pitch is preferably larger than the winding pitch of the primary coil wire. Specifically, for the predetermined pitch, the diameter of the second molybdenum wire is preferably 50 μm to 200 μm, and more preferably about 100 μm.

  In the third step, the lead portion of the electrode coil is formed by folding back. FIG. 3 is a diagram showing a winding procedure of the lead portion of the electrode coil. In FIG. 3, the primary coil wires 21, 22, and 23 are illustrated as one line for easy understanding of the description. As described in the above step, it is coiled. Also, in FIG. 3, at the end of the primary coil wire, the primary coil wire 21 that is densely wound for the first time, the primary coil wire 22 that is coarsely wound back, and the primary coil that is densely wound for the second time. The winding direction of the line 23 is indicated by an arrow.

  First, the primary coil wire 21 is wound around the second molybdenum wire from the start point to the end point of the lead at a pitch about twice the outer diameter of the primary coil wire. Next, the primary coil wire 22 is wound from the end point of the lead to the start point with a coarse pitch of 9 times or more of the pitch before the return, that is, 18 times or more of the outer diameter of the primary coil wire. Further, the lead coil 23 is folded back at the lead start point, and the primary coil wire 23 is wound from the lead start point to the end point at a pitch of about twice the outer diameter of the primary coil wire. Thereby, the structure of the lead part of the electrode coil is formed.

  Thereafter, the secondary coil wire is heat treated. The heat treatment is performed for about several tens of seconds at a temperature of about 1500 ° C. in a hydrogen atmosphere.

  In the fourth step, the overall structure of the electrode coil is formed. A part of the secondary coil wire formed in the third step is wound in a helical shape around a jig bar at a predetermined pitch to form a coil part structure of the electrode coil. The diameter of the jig bar is preferably larger than the winding pitch of the secondary coil wire. After winding, the coil is pulled out from the jig bar to form a final shape coil. Specifically, the diameter of the jig rod of the helical winding machine is preferably 200 μm to 2500 μm.

  Thereafter, heat treatment is performed. The heat treatment is performed for about several tens of seconds at a temperature of about 1500 ° C. in a hydrogen atmosphere.

  In the fifth step, the molybdenum wire is etched. The first and second molybdenum wires are melted with acid, leaving only the first and second tungsten wires. Thereby, an electrode coil is completed.

<Example>
As an example of a triple helical electrode for a hot cathode discharge lamp having an inner diameter of 2 mmφ, a tungsten wire 20 μmφ, a helical coil outer diameter 0.85 mmφ, a coil portion length 1.35 mm, a composite closely wound lead portion 4.8 mm, and a total length 7.0 mm The example of formation of the electrode coil of specification is shown.

  In the first step, a core wire was formed by winding a first molybdenum wire (diameter 20 μm) around a first tungsten wire (diameter 20 μmφ) at a pitch of 500 μm. In the second step, a primary coil wire was formed by winding a second tungsten wire (diameter: 10 μmφ) at a pitch of 20 μmφ around the core wire. In the third step, the primary coil wire was wound around a second molybdenum wire (diameter: 100 μmφ) with a pitch of 110 μmφ to form a secondary coil wire. Furthermore, the primary coil wire is wound around the second molybdenum wire at a pitch of 120 μm from the lead start point to the end point, folded at the lead end point, and the primary coil wire is wound at a pitch of 1200 μm from the lead end point to the start point. The lead coil was folded at the lead start point and the primary coil wire was wound at a pitch of 120 μm from the lead start point to the end point to form a lead portion of the electrode coil. Thereafter, heat treatment was performed at 1550 ° C. for 60 seconds in a hydrogen atmosphere. In the fourth step, a secondary coil wire was helically wound around a helically wound jig bar (diameter 400 μmφ) to form a coil part structure of the electrode coil. Thereafter, heat treatment was performed at 1550 ° C. for 60 seconds in a hydrogen atmosphere. In the fifth step, the first and second molybdenum wires were melted with acid to complete the final electrode coil.

  FIG. 4 shows an overall view of the electrode coil in this embodiment, and FIG. 5 shows the structure of the lead portion of the electrode coil in this embodiment. In order to show the structure of the electrode coil more clearly, no electron emitting material is applied to the coil.

  As shown in FIG. 4, the electrode coil has a coil portion 30 and a lead portion 32 as a whole. 4 and 5, the first and second molybdenum wires are melted to form a primary coil wire in which the second tungsten is helically wound so as to have a gap with respect to the first tungsten wire serving as the core wire. You can see that

  Thus, by putting a molybdenum wire as a core wire and melting the molybdenum wire, the electrode coil can have a structure having many complicated spaces. Such a space is effective for fixing as much electron emitting material as possible in the coil.

  Further, in the lead portion 32, as shown in FIG. 5, the primary coil wires 21, 22, and 23 are folded back and wound around the primary coil wire 21 wound at the first dense pitch. The primary coil wire 23 wound with a dense pitch is inserted, and the second tungsten wires constituting the primary coil wires 21 and 23 are intertwined with each other.

  According to the present embodiment, since the winding structure of the lead portion of the electrode coil is entangled and becomes dense, mechanical strength is enhanced. In addition, since the coil wires are in close contact with each other at the lead portion, the electrical resistance is reduced and the heating efficiency is improved. Specifically, it is considered that there is an effect that the power consumption required for heating the main part of the heater which is supposed to generate heat can be reduced by 5% to 10%.

  In the present invention, the helical coil is described as being suitable for the triple-winding electrode coil main part. However, as a simpler shape, the helical shape is not wound, and a V-shaped bent shape or an M-shaped bent shape can be easily obtained. Conceivable.

  Such an electrode coil can be used for an illumination device for a liquid crystal display.

  As a comparative example, FIG. 6 shows an example of a coil in which the lead portion is not reinforced. This is an example in which the composite coil is not formed in the lead portion by the secondary coil wire described in the present embodiment. It can be seen that the winding at the end of the coil is not a tightly wound structure and the vicinity of the weld with the lead wire is not strengthened. In such a winding structure, there is a risk of deformation due to mechanical vibration or thermal strain during heating.

It is a figure which shows the structure of the hot cathode type discharge lamp in background art. It is a figure which shows the structure of the hot cathode type discharge lamp in background art. It is a figure which shows the manufacturing method of the electrode coil in embodiment of this invention. It is a figure which shows the structure of the electrode coil in embodiment of this invention. It is an enlarged view which shows the structure of the lead part of the electrode coil in embodiment of this invention. It is a figure which shows the structure of the electrode coil in background art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Hot cathode type discharge lamp, 2 glass tube, 3a, 3b lead wire (lead), 4 electrodes, 5 coil part, 6 heater, 7 electron emission substance, 8 phosphor, 9 coil heater, 10a, 10b lead (foot) 11 scattering prevention member, 12 electron emitting material, 21, 22, 23 primary coil wire, 30 coil portion, 32 lead portion.

Claims (8)

It is constituted by a primary coil wire consisting of a core wire that forms an electrode coil main part and a winding wound around the core wire,
The primary coil wire is wound twice,
A single tightly wound portion formed by two closely wound primary coil wires in the same winding direction and at a predetermined pitch;
A double winding part formed by a primary coil wire wound densely at the predetermined pitch and a primary coil wire wound more coarsely than the predetermined pitch;
An electrode coil for a hot cathode discharge lamp, comprising a composite winding portion comprising: It is an electrode coil for hot cathode type discharge lamps according to claim 1,
The double-winding portion is composed of a first primary coil wire that is densely wound at the predetermined pitch and a second primary coil wire that is folded back and wound more coarsely than the predetermined pitch. Configured,
A third primary coil wire wound from the outside of the double winding portion at the same winding direction and the same pitch as the first primary coil wire, the first primary coil wire, An electrode coil for a hot cathode type discharge lamp, characterized in that the single-contact winding portion is configured. It is an electrode coil for hot cathode type discharge lamps according to claim 2,
The electrode coil for a hot cathode discharge lamp, wherein the first primary coil wire and the third primary coil wire are intertwined with each other in the single-contact winding portion. It is an electrode coil for hot cathode type discharge lamps according to claim 2 or 3,
An electrode coil for a hot cathode discharge lamp, wherein the winding pitch of the second primary coil wire is 9 times or more of the predetermined pitch. It is an electrode coil for hot cathode type discharge lamps according to any one of claims 1 to 4,
The electrode coil for a hot cathode discharge lamp, wherein the predetermined pitch is approximately twice the outer diameter of the primary coil wire. It is an electrode coil for hot cathode type discharge lamps according to any one of claims 1 to 5,
An electrode coil for a hot cathode discharge lamp, wherein the double winding portion is formed in a lead portion.   A hot-cathode discharge lamp for a liquid crystal display using the electrode coil for a hot-cathode discharge lamp according to any one of claims 1 to 6 as an electrode.   The illuminating device for liquid crystal displays using the electrode coil for hot cathode discharge lamps as described in any one of Claims 1-6 as an electrode.