JP2005005186A - Light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a fixing method of a second electrode on the outer surface of an arc tube of a light source device with high luminous efficiency. <P>SOLUTION: The light source device is equipped with the arc tube 20; a discharge medium sealed on the inside of the arc tube 20; and first and second electrodes 21, 22 for exciting the discharge medium. Since the first electrode 21 is arranged on the inside or the outside of the arc tube 2 and the second electrode 22 is fixed to the outer surface of the arc tube 20 with a thermosetting insulating material in a plurality of contact parts where the distance from the first electrode 21 is different and discontinuous, the second electrode 22 resistant to mechanical vibration can be realized. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a light is output to the outside of the arc tube by applying a voltage between the first electrode provided in the arc tube filled with the rare gas and the second electrode provided outside the arc tube. The present invention relates to a method of fixing a second electrode in a light source device that generates the above.
[0002]
[Prior art]
In recent years, in backlights (light source devices) used for liquid crystal displays and the like, in addition to research on backlights using mercury, research on backlights that do not use mercury (hereinafter sometimes referred to as mercury-less backlights) has become active. Has been done. Since the mercury-less backlight does not use mercury, the luminous flux rises quickly because it does not cause a decrease in luminous efficiency due to an increase in mercury temperature. In addition, a mercury-less backlight is environmentally preferable.
[0003]
As a light source device that does not use mercury, a discharge lamp device having a bulb in which a rare gas is sealed, an internal electrode arranged inside the bulb, and an external electrode arranged outside the bulb is disclosed. (See Patent Document 1). The external electrode is a linear electrode, and is formed on the outer surface of the bulb so as to be parallel to the central axis of the bulb. This rare gas discharge lamp device emits light by applying a voltage to an internal electrode and an external electrode.
[0004]
Also disclosed is a rare gas discharge lamp comprising an arc tube filled with a rare gas, an internal electrode formed inside the arc tube, and an external electrode spirally formed on the outer peripheral surface of the arc tube. (Patent Document 2).
[0005]
Further, as a discharge lamp using a rare gas as a main discharge medium, a discharge lamp including an airtight container, an internal electrode disposed inside the airtight container, and an external electrode having a coil shape or a mesh shape is disclosed. (Patent Document 3). This publication discloses a method of fixing an external electrode using a shrinkable tube.
[0006]
[Patent Document 1]
JP-A-5-29085 [Patent Document 2]
Japanese Patent Laid-Open No. 10-112290 [Patent Document 3]
Japanese Patent Laid-Open No. 2001-325919
[Problems to be solved by the invention]
However, if a linear external electrode is formed over almost the entire area of the arc tube, the discharge may concentrate in the vicinity of the external electrode and the discharge contracts, and the discharge medium may not be excited efficiently. May decrease. On the other hand, even when a spiral external electrode is provided on the outer surface of the arc tube, since the external electrode is in linear contact with the outer surface of the arc tube, the discharge tends to contract.
[0008]
In view of such a situation, there is a light source device disclosed by the present inventors in Japanese Patent Application No. 2002-262047 and a liquid crystal display using the light source device. In the light source device of the present invention, since the second electrode and the discharge tube are in contact with each other at a plurality of portions having different distances from the first electrode, the discharge does not concentrate in the vicinity of the second electrode and high light emission is achieved. It became possible to achieve efficiency.
[0009]
An object of the present invention is to provide an improved fixing structure of the second electrode on the outer surface of the arc tube in the light source device.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a light source device of the present invention includes at least one arc tube, a discharge medium enclosed in the arc tube, and first and second electrodes for exciting the discharge medium. The first electrode is disposed inside or outside the arc tube, and the second electrode is an insulator with a plurality of discontinuous contact portions that are different in distance from the first electrode. Is fixed to the outer surface of the arc tube. According to this light source device, a stable light beam can be obtained.
[0011]
In the light source device, the plurality of contact portions may be arranged along a tube axis direction of the arc tube.
[0012]
In the light source device, the insulator may have a heat dissipation property.
[0013]
In the light source device, the inner peripheral surface of the arc tube may be coated with a phosphor layer that converts generated light into a predetermined visible light wavelength.
[0014]
In the light source device, the insulator may reflect visible light.
[0015]
In the light source device, the insulator may be silicone rubber.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts may be denoted by the same reference numerals and redundant description may be omitted.
[0017]
(Embodiment 1)
In Embodiment 1, an example of a light source device of the present invention will be described. The structure of the light source device 10 of Embodiment 1 is shown in FIG. The figure seen from the side surface of the direction of the arrow (A) of Fig.1 (a) is shown in FIG.1 (b). A cross-sectional view taken along line II in FIG. 1A is shown in FIG. The light source device 10 includes an arc tube 20, a first electrode 21 disposed inside the arc tube 20, and a second electrode 22 disposed on the outer surface of the arc tube 20. A lead wire 24 is connected to the first electrode 21. The second electrode 22 is grounded. The first electrode 21 may be external.
[0018]
The arc tube 20 is formed of a translucent material, for example, borosilicate glass. The arc tube 20 may be formed of quartz glass, soda glass, or lead glass. The outer diameter of the glass tube used for the arc tube 20 is usually about 1.2 mm to 15 mm. The distance between the outer surface and the inner surface of the glass tube, that is, the thickness of the glass tube is usually about 0.2 mm to 1.0 mm. The arc tube 20 is not limited to a linear shape, and may have other shapes. For example, it may be L-shaped, U-shaped or rectangular. In the example of FIG. 1, two linear arc tubes 20 are provided.
[0019]
The arc tube 20 is sealed, and a discharge medium (not shown) is sealed therein (the same applies to the following embodiments). The discharge medium includes at least xenon. The pressure of the gas sealed in the arc tube 20, that is, the pressure inside the arc tube 20 is about 13 kPa to 36 kPa.
[0020]
As shown in FIG. 1C, a phosphor layer 23 is formed on the inner surface of the arc tube 20. The phosphor layer 23 is formed in order to convert the wavelength of light emitted from the discharge medium. By changing the material of the phosphor layer 23, light of various wavelengths can be obtained. For example, white light and visible light such as red, green, and blue (RGB) light can be obtained. The phosphor layer 23 can be formed of a material generally used for a discharge lamp.
[0021]
The first electrode 21 is formed inside one end of the arc tube 20. The first electrode 21 can be formed of a metal such as tungsten or nickel. The surface of the first electrode 21 may be covered with a metal oxide layer such as cesium oxide, magnesium oxide, or barium oxide. By using such a metal oxide layer, the lighting start voltage can be reduced and electrode deterioration due to ion bombardment can be prevented. The surface of the first electrode 21 may be covered with a dielectric layer (for example, a glass layer).
[0022]
The second electrode 22 is formed of a metal such as copper, aluminum, or phosphor bronze. The second electrode 22 is a thermosetting insulator 25 and is a plurality of discontinuous portions (contact portions) that are different in distance from the first electrode 21 and are discontinuous along the tube axis direction of the arc tube 20. It is fixed so as to be in contact with the outer surface.
[0023]
As a method for fixing the second electrode to the arc tube 20, first, an appropriate amount of sol-like thermosetting insulator 25 is poured into the surface where the second electrode 22 contacts the arc tube 20 with a dispenser or the like. Next, the arc tube 20 is pressed against the surface and heated in an atmosphere of 100 to 400 ° C. for 5 to 60 minutes. By heating, the thermosetting insulator 25, which is in the form of a sol, is cured, and the second electrode 22 is fixed to the arc tube 20.
[0024]
In the light source device 10, a discharge is generated by applying a voltage between the first electrode 21 and the second electrode 22 by the lighting circuit 13, and a discharge medium (not shown) is excited. The excited discharge medium emits ultraviolet rays (not shown) when transitioning to the ground state. This ultraviolet light (not shown) is converted into visible light (not shown) by the phosphor layer 23 and emitted from the arc tube 20. Visible light (not shown) becomes light having a uniform intensity on the surface by the light guide plate 26 and the reflection sheet 27 formed of acrylic resin or the like.
[0025]
In the light source device 10, since the second electrode 22 is firmly fixed to the arc tube 20 by the thermosetting insulator 25, the second electrode 22 is attached to the arc tube 20 even if mechanical vibration occurs in the light source device 10. The contact area can be kept constant. The merit that the area where the second electrode 22 is in contact with the arc tube 20 can be kept constant will be described below.
[0026]
If the area where the second electrode 22 is in contact with the arc tube 20 fluctuates due to mechanical vibration or the like, the discharge current decreases when the contact area is small, and the discharge current when the contact area is large. Becomes larger. Since the increase / decrease in the discharge current changes the visible light amount radiated from the arc tube 20, the visible light amount periodically changes due to mechanical vibration. Further, when the contact failure increases, a slight discharge may occur in the air and ozone may be generated. In the present invention, even when mechanical vibration occurs, the contact area can be kept constant, so that the visible light amount can be kept constant, and the possibility that ozone is generated can be reduced.
[0027]
In addition, by blending a heat dissipation filler with the thermosetting insulator 25, the thermosetting insulator 25 has heat dissipation, and heat generated from the arc tube 20 can be efficiently released to the outside.
[0028]
Moreover, the visible light (not shown) radiated | emitted from the arc_tube | light_emitting_tube 20 is efficiently guide | induced to the light-guide plate 26 by mix | blending the filler which fully reflects visible lights, such as a titanium oxide, with the thermosetting insulator 25. FIG. Is possible.
[0029]
Further, by using the thermosetting insulator 25 as a silicone rubber (for example, KE1223 manufactured by Shin-Etsu Chemical Co., Ltd.), it is possible to realize the long-life light source device 10 having excellent insulating characteristics.
[0030]
(Embodiment 2)
In Embodiment 2, an example will be described that shows that the degree of freedom of the shape of the second electrode is increased because the second electrode is firmly fixed to the arc tube in the light source device of the present invention.
[0031]
The structure of the light source device 11 of Embodiment 2 is shown in FIG. FIG. 2B shows a cross-sectional view taken along line II-II in FIG. A schematic view of the second electrode 32 and the electrode substrate 38 of FIGS. 2A and 2B as viewed from the arrow (b) on the arc tube 30 side is shown in FIG. The light source device 11 of FIG. 2A includes an arc tube 30, a first electrode 31 disposed inside the arc tube 30, a second electrode 32 disposed outside the arc tube 30, and an electrode substrate 38. With. A lead wire 34 is connected to the first electrode 31. The lead wire 34 has the second electrode 32 grounded. In the light source device 11, the first electrode 31 is connected to the lighting circuit 14 via the lead wire 34.
[0032]
The structure and operation of the arc tube 30 are exactly the same as in the first embodiment.
[0033]
The difference from the first embodiment is that the second electrode 32 is formed on the electrode substrate 38. The electrode substrate 38 has a thickness of 0.2 to 2 mm and is made of an insulating material such as glass. The second electrode 32 is formed by screen printing a metal paste containing a metal powder (for example, silver powder) and a resin on the electrode substrate 38. As other methods, metal deposition on the electrode substrate 38, dip coating, or the like may be used.
[0034]
The electrode substrate 38 on which the second electrode 32 is formed is fixed to the arc tube 32 by the thermosetting insulator 35 as in the first embodiment.
[0035]
The merit of the above structure is that the machining of the second electrode is not required, so the degree of freedom in designing the shape of the second electrode 32 is greatly increased, and the second electrode having the optimum shape for each type of the light source device 11 can be obtained. Can be provided.
[0036]
The embodiments of the present invention have been described above by way of examples. However, the present invention is not limited to the above-described embodiments, and can be applied to other embodiments based on the technical idea of the present invention.
[0037]
【The invention's effect】
In the light source device according to the present invention, the second electrode is fixed to the outer surface of the arc tube by an insulator at a plurality of discontinuous contact portions with different distances from the first electrode. A light source device having a strong second electrode can be realized.
[Brief description of the drawings]
FIG. 1A is a schematic plan view showing an example of a light source device according to the present invention. FIG. 1B is a side view of the light source device according to the present invention as viewed from an arrow A. FIG. FIG. 2A is a schematic plan view showing an example of a light source device according to the present invention, and FIG. 2B is a schematic plan view showing an example of the light source device according to the present invention. Sectional view (c) of the light source device according to the present invention as viewed from the arrow (B) on the arc tube 30 side of the second electrode 32 and the electrode substrate 38 of FIG.
10, 11 Light source device 13, 14 Lighting circuit 20, 30 Arc tube 21, 31 First electrode 22, 32 Second electrode 23, 33 Phosphor layer 24, 34 Lead wire 25, 35 Thermosetting insulator 26, 36 Light guide plate 27, 37 Reflective sheet 38 Electrode substrate

Claims (6)

Arc tube,
A discharge medium enclosed in the arc tube;
First and second electrodes for exciting the discharge medium;
The first electrode is disposed inside or outside the arc tube;
The light source device, wherein the second electrode is fixed to the outer surface of the arc tube with an insulating material at a plurality of discontinuous contact portions having different distances from the first electrode. The light source device according to claim 1, wherein the plurality of contact portions are arranged along a tube axis direction of the arc tube. The light source device according to claim 1, wherein the insulator has a heat dissipation property. The light source according to any one of claims 1 to 3, wherein a phosphor layer for converting generated light into visible light having a predetermined wavelength is coated on an inner peripheral surface of the arc tube. apparatus. The light source device according to claim 4, wherein the insulator reflects visible light. The light source device according to claim 1, wherein the insulator is silicone rubber.

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