JP2003178717A - Light source device and liquid crystal display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source having high luminous efficiency and a liquid crystal display device using the same. <P>SOLUTION: The light source device comprises at least one light-emitting tube 20, a discharge medium filled in the light-emitting tube 20, and a first and a second electrodes 21, 22 for exciting the discharge medium. And the first electrode 21 is formed inside or outside the light-emitting tube 20, and the second electrode 22 contacts the outside face of the light-emitting tube 20 at a plurality of contacting parts that are in the different distance from the first electrode 21 and are discontinuous. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device including an arc tube in which a discharge medium is enclosed and electrodes for exciting the discharge medium, and a liquid crystal display using the same.

[0002]

2. Description of the Related Art In recent years, in backlights (light source devices) used for liquid crystal displays and the like, in addition to research on backlights that use mercury, backlights that do not use mercury (hereinafter sometimes referred to as mercuryless backlights). Is being actively researched. The mercury-less backlight is
Since mercury is not used, the luminous efficiency does not decrease as the mercury temperature rises, and the luminous flux rises quickly. A mercury-less backlight is environmentally preferable.

As a light source device that does not use mercury, a discharge lamp device having a bulb filled with a rare gas, 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 valve so as to be parallel to the central axis of the valve. This rare gas discharge lamp device emits light by applying a voltage to the inner electrode and the outer electrode.

Also disclosed is a rare gas discharge lamp having 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. (See Patent Document 2).

Further, as a discharge lamp using a rare gas as a main discharge medium, there is a discharge lamp having an airtight container, an internal electrode arranged inside the airtight container, and an external electrode having a coil shape or a mesh shape. It is disclosed (see Patent Document 3). This publication discloses a method of fixing an external electrode using a shrinkable tube.

Further, the discharge lamp disclosed in Patent Document 4 is provided with an arc tube filled with a rare gas, an internal electrode and an external electrode. The internal electrodes are formed on almost the entire area of the arc tube along the central axis of the arc tube. The external electrode is
It is a linear electrode and is formed on the outer surface of the arc tube so as to be parallel to the central axis of the arc tube.

[0007]

[Patent Document 1] JP-A-5-29085

[0008]

[Patent Document 2] Japanese Patent Laid-Open No. 10-112290

[0009]

[Patent Document 3] Japanese Patent Laid-Open No. 2001-325919

[0010]

[Patent Document 4] US Pat. No. 5,604,410

[0011]

However, if a linear external electrode is formed over almost the entire area of the arc tube, the discharge is concentrated near the external electrode and the discharge contracts, so that the discharge medium cannot be efficiently excited. In some cases, as a result, luminous efficiency may decrease. On the other hand, even when a spiral external electrode is provided on the outer surface of the arc tube, the external electrode linearly contacts the outer surface of the arc tube, so that the discharge easily contracts.

In view of such circumstances, it is an object of the present invention to provide a novel light source device and a liquid crystal display device using the same.

[0013]

In order to achieve the above object, the light source device of the present invention comprises at least one arc tube,
A discharge medium enclosed inside the arc tube, and first and second electrodes for exciting the discharge medium, wherein the first electrode is formed inside or outside the arc tube. The second electrode is in contact with the outer surface of the arc tube at a plurality of discontinuous contact portions that are different in distance from the first electrode. In this specification,
The "contact between the second electrode and the outer surface of the arc tube" includes the case where the second electrode and the arc tube are in contact with each other through a dielectric or the like. “Contact” means a space between two members (air spac
e) does not exist.

In the above light source device, the plurality of contact portions are
It may be arranged along the direction of the tube axis of the arc tube.

In the above light source device, the first electrode may be formed at an end portion of the arc tube, and the surface density of the plurality of contact portions may increase as the distance from the first electrode increases.

In the above light source device, the surface of the first electrode may be covered with a dielectric.

The light source device may further include a phosphor layer formed on the inner surface of the arc tube.

In the light source device, the arc tube may include a glass tube and a dielectric layer formed on an outer surface of the glass tube.

In the above light source device, the second electrode may be in contact with the arc tube via a dielectric.

In the above light source device, the discharge medium may contain xenon gas, and the discharge medium may further contain mercury. Further, in the above light source device, the discharge medium may not contain mercury.

The light source device further includes a support plate,
The arc tube may be arranged on a side surface of the support plate.

In the above light source device, the support plate may take in light emitted from the arc tube and emit the light from one main surface of the support plate.

In the above light source device, a support plate and a plurality of the arc tubes supported by the support plate are provided, and the second electrode includes a plurality of linear electrodes arranged in parallel. May be arranged so as to be orthogonal to the linear electrode.

In the above light source device, the arc tube may include a plurality of first arc tubes, a plurality of second arc tubes, and a plurality of third arc tubes. The first, second, and third arc tubes are repeatedly arranged in this order, and the first, second, and third arc tubes emit light of different wavelengths.

The light source device may further include a third electrode disposed on the inner surface of or around the arc tube.
The third electrode is linearly formed so as to be parallel to the tube axis of the arc tube, and has a potential E of the first electrode.
1, the potential E2 of the second electrode, and the potential E3 of the third electrode are | E2 | ≦ | E3 | <| E1 | and 0.
The relationship of ≦ E1 · E3 is satisfied.

In the above light source device, both ends of the third electrode may be connected to the second electrode at two contact portions selected from a plurality of the contact portions.

A liquid crystal display of the present invention is a liquid crystal display including the above-mentioned light source device of the present invention and a liquid crystal panel through which light emitted from the light source device is transmitted. The light source device includes at least one arc tube, a discharge medium sealed inside the arc tube, and first and second electrodes for exciting the discharge medium, wherein the first electrode is The second electrode is formed inside or outside the arc tube, and contacts the outer surface of the arc tube at a plurality of discontinuous contact portions having different distances from the first electrode.

The light source device of the liquid crystal display is
A light guide plate that receives the light emitted from the arc tube and emits the light from one main surface may be further provided. The liquid crystal panel is arranged to face the light guide plate.

Further, the light source device of the liquid crystal display includes a support plate and a plurality of the arc tubes supported by the support plate, and the second electrodes are a plurality of linear electrodes arranged in parallel. And the arc tube may be arranged so as to be orthogonal to the linear electrode.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. In the following description, the same reference numerals may be given to the same parts, and overlapping description may be omitted.

(Embodiment 1) In Embodiment 1, an example of a light source device (discharge lamp device) of the present invention will be described. The configuration of the light source device 10 of the first embodiment is shown in FIG. Figure 1
A cross-sectional view taken along line I-I of (A) is shown in FIG.
The light source device 10 includes an arc tube (discharge tube) 20 and an arc tube 20.
And a second electrode 22 arranged outside the arc tube 20. A lead 24 is connected to the first electrode 21.

The arc tube 20 is made of a translucent material,
For example, it is formed of borosilicate glass. The arc tube 20 may be made of quartz glass, soda glass, or lead glass. The arc tube 20 may include a dielectric layer (for example, a resin layer) arranged on the outer surface thereof.
An example of such an arc tube 20 is shown in FIG. The arc tube 20 includes a tube 20a and a dielectric layer 20b formed on the outer surface of the tube 20a. The tube 20a is made of, for example, borosilicate glass. For the dielectric layer 20, for example, a multilayer film made of polyester resin or a thin film made of titanium oxide or silicon oxide can be used. The outer diameter of the glass tube used for the arc tube 20 is normally 1.2 mm to 15 m.
It is about m. Also, the distance between the outer surface and the inner surface of the glass tube,
That is, the thickness of the glass tube is usually 0.2 mm to 1.0
It is about mm. When the dielectric layer is formed on the surface of the glass tube, its thickness is usually about 0.5 μm to 100 μm. The arc tube 20 is not limited to the linear shape,
Other shapes may be used. For example, it may be L-shaped, U-shaped or rectangular.

The arc tube 20 is sealed, and a discharge medium (not shown) is sealed inside the arc tube 20 (the same applies to the following embodiments). A rare gas can be used as the discharge medium used in the light source device 10.
The rare gas is at least one selected from krypton gas, argon gas, helium gas and xenon gas.
Two gases can be used. The discharge medium may further contain mercury in addition to the rare gas. However, when the discharge medium does not contain mercury, it is possible to prevent a change in luminous efficiency due to a change in mercury vapor pressure due to a change in ambient temperature. In addition, the wavelength of ultraviolet rays emitted from xenon gas is close to the wavelength of ultraviolet rays emitted from mercury.
Therefore, by using xenon gas as the rare gas, there is an advantage that the same fluorescent substance as the fluorescent lamp using mercury can be used. The above-mentioned discharge medium can be applied as the discharge medium of the following embodiments.

As shown in FIG. 1B, a phosphor layer 23 is formed on the inner surface of the arc tube 20. Phosphor layer 23
Are formed to convert the wavelength of light emitted from the discharge medium. Light of various wavelengths can be obtained by changing the material of the phosphor layer 23. For example, white light and 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.

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 the deterioration of the electrode due to ion bombardment can be prevented. Moreover, the surface of the first electrode 21 may be covered with a dielectric layer (for example, a glass layer). Figure 1
FIG. 1D shows a cross-sectional view of the first electrode 21 including the metal electrode 21a and the dielectric layer 21b formed so as to cover the metal electrode 21a. By using such a dielectric layer, the electric current at the time of discharge can be suppressed. As a result, it is possible to suppress the continuous flow of current during discharge and stabilize the discharge. The first electrode 21 may be formed outside the arc tube 20 as described in the second embodiment.

The second electrode 22 is formed outside the arc tube 20. The second electrode 22 can be formed of a conductive material. For example, the second electrode 22 may be formed of a metal such as copper, aluminum or phosphor bronze, or may be formed of a metal paste containing a metal powder (for example, silver powder) and a resin. The second and third electrodes described below can be formed of the same material. The second electrode 22 is in contact with the outer surface of the arc tube 20 at a plurality of discontinuous portions (contact portions) having different distances from the first electrode 21.

A sectional view taken along the line II-II in FIG. 1A is shown in FIG. The second electrode 22 has a plurality of contact portions 22.
It is in contact with the arc tube 20 at P. Multiple contact parts 2
2P have different distances from the first electrode 21 and are separated from each other. The plurality of contact portions 22P are arranged along the tube axis direction AX of the arc tube 20. As shown in FIG. 2B, the plurality of contact portions 22P may form a plurality of groups arranged along the tube axis direction AX of the arc tube 20. The contact portions 22P included in each group are arranged along the tube axis direction AX of the arc tube 20. The contact portions 22P do not have to be aligned along the tube axis direction AX. Further, the shape of the contact portion 22P is not limited to the square. For example, the shape of the contact portion 22P may be rectangular or linear. Further, as shown in FIG. 2B, as long as the contact portions having different distances from the first electrode 21 are included, the contact portions having the same distance from the first electrode 21 may be included. 1
The length of the two contact portions 22P in the tube axis direction is, for example, in the range of 0.1% to 5% of the length of the arc tube 20 in the tube axis direction, for example, in the range of 0.5% to 3%. . The distance between the two contact portions 22P adjacent to each other in the tube axis direction is preferably larger than the thickness of the arc tube 20 and not more than 10 times the maximum inner diameter of the arc tube 20. By making the interval larger than the thickness of the arc tube 20, the discharge is generated by the second electrode 2.
It is possible to prevent linear shrinkage along the line 2. Further, by setting the interval to 10 times or less of the maximum inner diameter of the arc tube 20, it is possible to prevent non-uniform discharge. Further, in order to prevent light from being shielded by the second electrode 22, it is preferable that the length of the contact portion 22p in the circumferential direction of the arc tube 20 be half or less of the circumference of the arc tube 20.

An example of the light source device 10 will be described. The arc tube 20 has, for example, an outer diameter of 2.6 mm and an inner diameter of 2.0.
mm and the length is 250 mm. Inside the arc tube, as a phosphor layer, a three-wavelength emission type rare earth phosphor used in a general fluorescent lamp is applied. The length of the contact portion 22P in the tube axis direction is 3 mm, and the interval in the tube axis direction is 1 mm. The pressure inside the arc tube is about 2
A mixed gas of xenon gas and argon gas is filled so that the pressure becomes 1 kPa.

In the light source device 10, the first electrode 21 and the second electrode 21
A discharge is generated by applying a voltage between the electrode 22 and the electrode 22, and the discharge medium is excited. The excited discharge medium is
It emits ultraviolet rays when it moves to the ground state. This ultraviolet ray is converted into visible light by the phosphor layer 23 and emitted from the arc tube 20.

Below, the first electrode 21 and the second electrode 22
An example of the voltage applied between and will be described. The voltage applied between the first electrode 21 and the second electrode 22 may be a sine wave or a rectangular wave, and the polarity may or may not change. When mercury is not contained inside the arc tube 20, that is, when the discharge medium is only rare gas, the second electrode 22 is connected to the ground and the polarity of the voltage changes with respect to the first electrode 21. It is preferable to apply a rectangular wave voltage. An example of such an applied voltage is shown in FIG. In the example shown in FIG. 3A, the applied voltage to the first electrode 21 is modulated between 0 volt and the positive voltage V1. The value of the ratio (T1 / T2) between the time T1 for applying the voltage V1 and the period T2 of the rectangular wave is preferably about 0.15 to 0.5. The frequency of the rectangular wave is in the range of 10 kHz to 60 kHz, for example. The current flowing between the two electrodes when the voltage shown in FIG. 3 (A) is applied is shown in FIG. 3 (B). A current corresponding to the differential waveform of the applied voltage flows between the first electrode 21 and the second electrode 22.

FIG. 4 shows an example of the structure of the lighting circuit 13 for applying the voltage shown in FIG. 3 (A). The lighting circuit 13 is connected between the first electrode 21 and the second electrode 22. The second electrode 22 is usually connected to ground. The lighting circuit 13 includes an AC power supply 13a, a rectifier circuit 13b, a smoothing circuit 13c, a booster circuit 13d, and a switching circuit 13e. These circuits include
A general circuit can be used. The AC voltage generated by the AC power supply 13a is converted into a DC positive voltage by the rectifier circuit 13b. The rectified voltage is smoothed by the smoothing circuit 13c and boosted by the boosting circuit 13d. The boosted voltage is applied for a predetermined time T1 by the switching circuit 13e. In this way
A rectangular wave voltage is applied.

In the light source device 10, since the second electrode 22 discontinuously contacts the arc tube 20, it is possible to prevent the discharge from contracting to the second electrode 22 side. Therefore, in the light source device 10, uniform discharge is likely to be obtained even when the filled gas pressure is increased or the input power is increased. As a result, in the light source device 10, the discharge efficiency can be increased,
5 to 2 compared with the conventional light source device to which the same electric power is input
In some cases, 0% brightness improvement can be achieved. Further, in the light source device 10, since the second electrode 22 can be easily fixed so that the second electrode 22 contacts the arc tube 20, it can be easily manufactured at low cost.

The light source device of the present invention may further include a linear third electrode arranged parallel to the central axis of the arc tube 20 (the same applies to the light source devices of the following embodiments. ). An example of such a light source device is shown in FIG. 5 is a cross-sectional view taken along line VV in FIG.
It shows in (B). The light source device 10 a of FIG. 5A includes the arc tube 20, the first electrode 21, the second electrode 52, and the third electrode 53. First electrode 21 and second electrode 52
A lighting circuit 13 is connected to.

The second electrode 52 of the light source device 10a includes a plurality of cylindrical electrodes 52a. The electrode 52a is the arc tube 20.
Are arranged around. The electrode 52a can be formed of, for example, metal or a metal paste (for example, silver paste).

The third electrode 53 has a linear shape, and the arc tube 2
It is formed on the outer surface of the arc tube 20 so as to be parallel to the central axis of zero. The third electrode 53 is formed discontinuously. The third electrode 53 can be formed of, for example, metal or metal paste. In the example shown in FIGS. 5A and 5B, the third electrode 53 is connected to two adjacent electrodes 52a. However, the second electrode 52 and the third electrode 53
And may not be connected. The potential of the third electrode 53 may be the same as the potential of the second electrode 52 or a potential between the potential of the first electrode 21 and the potential of the second electrode 52.
That is, the potential E1 of the first electrode, the potential E2 of the second electrode, and the third electrode E3 are | E2 | ≦ | E3 | <|
The relationship of E1 | and 0 ≦ E1 · E3 is satisfied.

The width of the third electrode 53 is preferably narrow.
By making the width of the third electrode 53 smaller than the thickness of the arc tube 20, it is possible to suppress the adverse effect on the discharge. The third electrode 53 facilitates stabilizing the discharge. The third electrode 53 is used for the arc tube 2
It may be formed on the inner surface of 0. In that case, the phosphor layer 23
Are formed so as to cover the third electrode 53. In this case, the third electrode 53 is preferably made of a transparent conductive material containing tin oxide as a main component or a transparent conductive material containing indium oxide as a main component.

(Second Embodiment) In the second embodiment, another example of the light source device of the present invention will be described. The configuration of the light source device 60 of the second embodiment is schematically shown in FIG. Further, a cross-sectional view taken along line VIIA-VIIA in FIG. 6 is shown in FIG.
FIG. 7B is a cross-sectional view taken along line VIIB-VIIB in FIG. Note that the illustration of the diffusion plate is omitted in FIG. 6. Further, in FIGS. 7 (A) and 7 (B), illustration of the phosphor layer is omitted. Further, in FIGS. 6, 7 (A) and 7 (B), the arc tube at the right end is not shown.

The light source device 60 includes a support plate 61 and a diffusion plate 6.
2, the arc tube 20, the first electrode 21 arranged inside the arc tube 20, and the second electrode 72 arranged outside the arc tube 20. The second electrode 72 is connected (grounded) to the ground. First electrode 21 and second electrode 72
A voltage is applied by the lighting circuit 13 between and. As the lighting circuit 13, a general circuit including an inverter circuit can be used.

The support plate 61 is provided with a groove 61a having a V-shaped cross section in which the arc tube 20 is arranged. Arc tube 20
Are fixed to the support plate 61 by support members 63. The support plate 61 can be formed of resin, metal (for example, aluminum), or the like. The surface of the support plate 61 is preferably treated to improve the light reflection efficiency and the light diffusion efficiency. For example, titanium oxide powder may be applied to the surface or a reflection sheet may be attached. In addition, as long as insulation with the second electrode 72 can be secured, the support plate 61
A metal film may be formed on the surface of the. Further, the surface may be sandblasted. When light is emitted from the back surface side of the support plate 61, the support plate 61 is formed of transparent resin or glass. The shape of the support plate 61 is not limited and is determined according to the application. Another example of the shape of the support plate 61 is shown in FIGS. 8 (A) and 8 (B). In the example of FIG. 8B, the support member 63 is made of a conductive material and functions as a part of the second electrode.

The diffusion plate 62 is arranged so as to face the support plate 61 with the arc tube 20 interposed therebetween. The diffusion plate 62 is
It is arranged to uniformly diffuse the light emitted from the arc tube 20. The diffusion plate 62 is made of glass or translucent resin.

A plurality of arc tubes 20 are arranged in parallel on the support plate 61. There is no limit to the number of arc tubes 20.
May be one. A first electrode 21 is arranged inside one end of each arc tube 20. Arc tube 20
Can be easily removed from the support member 63.

The second electrode 72 comprises a plurality of linear electrodes 72a formed on the support plate 61. Multiple linear electrodes 7
2a is connected and connected to the lighting circuit 13. As shown in FIG. 6, the second electrode 72 is preferably connected to the ground. The arc tube 20 can be safely replaced by connecting the second electrode 72 to the ground. The plurality of linear electrodes 72a are arranged in stripes. Each linear electrode 72a is formed so as to be orthogonal to the central axis of the arc tube 20. The linear electrode 72a can be formed of, for example, a metal paste (for example, silver paste) or a metal film. The linear electrode 72a may be made of a conductive resin. In this case, the support plate 61 made of resin and the linear electrode 72a made of resin can be integrally molded.

If the distance between the linear electrodes 72a is constant, the brightness may decrease as the distance from the first electrode 21 increases. Therefore, as shown in FIG. 6, the distance between the adjacent linear electrodes 72a may be reduced as the distance from the first electrode 21 increases. In this case, as the distance from the first electrode 21 increases,
The width of the linear electrode 72a may be increased. With such a configuration, uniform light emission can be easily obtained.

As shown in FIG. 7A, the linear electrode 72a
Contacts the arc tube 20 at the groove 61a. That is, the second electrode 72 contacts the outer surface of the arc tube 20 at a plurality of contact portions having different distances from the first electrode 21. Similar to the contact portion 22P of FIG. 2B, the contact portions form two groups arranged parallel to the central axis of the arc tube 20. These contact portions are separated from each other and are not continuous.

In the light source device 60, the first electrode 21 and the second electrode 21
A discharge is generated by applying a voltage between the electrode 72 and the electrode 72, and the discharge medium is excited. The excited discharge medium is
It emits ultraviolet rays when it moves to the ground state. This ultraviolet ray is converted into visible light by the phosphor layer 23 and emitted from the arc tube 20. The emitted visible light becomes more uniform light by the diffusion plate 62. In this way, the light source device 60
Functions as a surface light source.

Although the light source device of the second embodiment has been described above, the light source device of the present invention is not limited to the illustrated form. Another form of the support member 63 is shown in FIGS.
It shows in (B). In the example of FIG. 9A, the support member 63 a is made of metal and is connected to the second electrode 72. Therefore, the support member 63a functions as a part of the second electrode 72. In the example of FIG. 9B, a support member 63b that is attachable to and detachable from the support plate 61 is used. Support members 63 and 63
It is preferable that b is formed of an insulating material such as resin. Instead of the supporting member 63, the arc tube may be fixed with an adhesive or an adhesive tape.

The first electrodes 21 may be arranged at both ends of the arc tube 20. An example of such a light source device is shown in FIG.
It shows in 0. In the light source device 100 of FIG. 10, the first electrodes 21 are arranged at both ends of the arc tube 20. First electrode 21
The greater the distance from, the narrower the interval between the linear electrodes 72a. In addition, at the central portion of the arc tube 20,
May have a smaller inner diameter or may be closed.

The first electrode 21 may be formed outside the arc tube 20. A first electrode 111 which is another mode of the first electrode 21 is shown in FIG. Also, FIG.
A cross-sectional view taken along line XI-XI in FIG. 1A is shown in FIG. The first electrode 111 has a cylindrical shape and is arranged on the outer peripheral portion of one end of the arc tube 20.

The first electrode 111 and the wiring can be connected by various methods. 12A to 12D show four connection methods. In FIGS. 12A to 12D, the first electrode 111 and the wiring 121 are connected to each other through the electrode terminal 122 (and the conductive member 123). An insulating layer 124 is formed around the electrode terminals 122. Figure 1
In the connection method of 2 (D), the arc tube 20 is easily attached and detached by using a spring.

Further, the first electrode 21 is the second electrode 72.
You may form on a support plate similarly to. An example of such a light source device is shown in FIG. In the light source device 130 of FIG. 13, the linear first electrode 131 is formed on the support plate 61 so as to be orthogonal to the arc tube 20. Such a first
Similarly to the second electrode 72, the electrode 131 of can be formed of a conductive material such as a metal paste.

The light source device of the second embodiment may further include a third electrode arranged parallel to the central axis of the arc tube 20. An example of such a light source device is shown in FIG. 14
The light source device 140 of 1 is different from the light source device 60 only in that a plurality of third electrodes 143 are provided, and therefore, redundant description will be omitted.

The third electrode 143 is the linear electrode 7 adjacent to the third electrode 143.
It is formed so as to connect 2a. The plurality of third electrodes 143 are discontinuous, that is, discretely arranged. The third electrode 143 can be formed of the same material as the linear electrode 72a.

According to the light source device of the second embodiment, the same effect as that of the light source device described in the first embodiment can be obtained. The light source device according to the second embodiment can be used as a surface light source and can be used as, for example, a backlight of a liquid crystal display. In that case, the liquid crystal panel is arranged above the diffusion plate 62.

(Embodiment 3) In Embodiment 3, another light source device of the present invention will be described. The light source device according to the third embodiment can be applied to a field sequential type display device. The configuration of the light source device 150 of the third embodiment is schematically shown in FIG.

In the light source device 150, three types of arc tubes 15 are used.
Arc tube group 151 composed of 1a, 151b and 151c
Are arranged in multiple numbers. The arc tubes 151a, 151b, and 151c are repeatedly arranged in order. The light emitting tubes 151a, 151b and 151c respectively emit light of different wavelengths. That is, each arc tube includes a phosphor layer corresponding to the emitted light. These phosphor layers can be formed of known phosphors. Specifically, the arc tube 151
a, 151b and 151c may emit red, green and blue lights, respectively. The arc tubes 151a, 151b and 151c are respectively
It may emit cyan, magenta, and yellow light. These arc tubes 151a, 151b and 1
When 51c is turned on at the same time, white light is obtained.

In the field-sequential display device, a liquid crystal panel is arranged above the light source device 150.
The arrangement of the liquid crystal panel is similar to that of the device shown in FIG.
As this liquid crystal panel, the same liquid crystal panel used in a monochrome liquid crystal display device can be applied. When displaying an image, arc tubes 151a, 151b and 151
blink c in sequence at high speed. As a result, for example, red, green and blue lights are emitted in sequence. In each pixel of the liquid crystal panel, the liquid crystal is driven to control the opening time (the time that light is transmitted). For example, in a pixel that displays yellow, the open time for red light emission may be equal to the open time for green light emission, and the open time for blue light emission may be zero. In such a case, red light emission and green light emission are combined by an afterimage, which is perceived by humans as yellow. In such a field-sequential display device, since the color filter of the liquid crystal panel is unnecessary, each pixel can be made small, and high-definition image display can be performed. If you do not change the pixel size,
Since the loss of light due to the color filter can be prevented, the light utilization rate can be increased.

The light source device of the present invention may further include a diffuser plate arranged between the liquid crystal panel and the arc tube (the same applies to the following embodiments). In addition, like the light source device 140, a third electrode may be included. The arc tube group 151 may be arranged on the side surface of the light guide plate.

(Embodiment 4) In Embodiment 4, another example of the light source device of the present invention will be described. The light source device of Embodiment 4 is shown in FIG. 17 is a cross-sectional view taken along the line XVII-XVII in FIG. The liquid crystal panel 170 is also shown in FIG.

The light source device 160 shown in FIG.
1, arc tube 20, first electrode 21 and second electrode 16
2 is provided.

The second electrode 162 is formed on the support plate 163. The support plate 163 fixes the arc tube 20 and functions as a reflection plate.

The arc tube 20 is disposed on the side surface of the light guide plate 161. The light emitted from the light emitting tube 20 is guided by the light guide plate 161.
Thus, the light is emitted from the surface 161a of the light guide plate 161 substantially uniformly. The light guide plate 161 can be formed of, for example, a transparent resin. The back surface 161b of the light guide plate 161 is provided with irregularities in order to make the emitted light uniform. Further, a reflective layer 164 is formed on the back surface 161b. The reflective layer 164 can be formed of, for example, titanium oxide or metal. Further, a diffusion sheet or a lens sheet may be arranged on the surface 161a of the light guide plate 161 depending on the usage situation. Also in the light source device 160, the second electrode 162
Are in contact with the arc tube 20 at a plurality of discontinuous and different distances from the first electrode 21.

When the light source device 160 is used in a liquid crystal display device, the liquid crystal panel 170 is used as the light guide plate 16 as shown in FIG.
1 (the same applies to the following light source devices).

The second electrode may be formed between the light guide plate and the arc tube. The configuration of such a light source device 180 is schematically shown in FIG. Further, FIG. 19 shows a sectional view taken along the line XIX-XIX. The liquid crystal panel 170 is also shown in FIG.

In the light source device 180, the second electrode 182 is arranged between the light guide plate 161 and the arc tube 20. The second electrode 182 can be formed with a metal paste or a conductive resin. The L-shaped arc tube 20 is supported by the support member 63. It is preferable to form a third electrode on the bent portion of the L-shaped arc tube 20. A reflection plate 183 that reflects the light emitted from the arc tube 20 toward the light guide plate 161 is disposed outside the arc tube 20. Light source device 180
When using as a backlight of a liquid crystal display device,
As shown in FIG. 19, the liquid crystal panel 17 is formed on the light guide plate 161.
0 is placed.

An example of the light source device 180 will be described.
The light guide plate can be made of acrylic resin and its size is 1.
It can be 60 mm × 93 mm. The L-shaped arc tube has a length of 252 mm, an outer diameter of 2.6 mm, and an inner diameter of 2.0 m.
It can be m. As the discharge medium, a mixed gas (pressure: about 21 kPa) of xenon gas and argon gas can be used. The length of one contact portion between the arc tube and the second electrode in the tube axis direction can be 3 mm. Further, the interval between the adjacent contact portions can be set to 1 mm.

The second electrode may be arranged between the arc tube and the reflector. Such a light source device 200
FIG. 20 schematically shows the configuration of the above. 21 is a cross-sectional view taken along the line XXI-XXI. The liquid crystal panel 170 is also shown in FIG.

In the light source device 200, the second electrode 202 is arranged between the arc tube 20 and the reflection plate 183. The second electrode 202 can be formed of a metal paste or a conductive resin. The L-shaped arc tube 20 is supported by the support member 63. A third electrode 203 is formed on the bent portion of the L-shaped arc tube 20. The reflection plate 183 arranged outside the arc tube 20 reflects the light emitted from the arc tube 20 toward the light guide plate 161. When the light source device 200 is used as a backlight of a liquid crystal display device, a liquid crystal panel 170 is arranged on the light guide plate 161 as shown in FIG.

Although the embodiments of the present invention have been described above with reference to examples, 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. .

[0079]

As described above, in the light source device of the present invention, 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. According to this light source device, it is possible to prevent the discharge from being concentrated near the second electrode. Further, since the light source device of the present invention does not need to use a contraction tube or the like when fixing the second electrode to the arc tube, it is easy to manufacture and the arc tube can have a free shape. The light source device of the present invention can be used as a light source for various devices such as a backlight of a liquid crystal display device.

[Brief description of drawings]

1A and 1B are a side view and a cross-sectional view showing an example of a light source device of the present invention, respectively, and FIG.
[Fig. 6] is a cross-sectional view showing another example of the light source device, and (D) is a cross-sectional view showing an example of the first electrode.

2A is a sectional view of the light source device shown in FIG. 1A, and FIG. 2B is a sectional view of another example.

FIG. 3A is a diagram showing an example of a voltage applied to the light source device of the present invention, and FIG. 3B is a diagram showing an example of a current flowing between electrodes.

FIG. 4 is a diagram schematically showing an example of a lighting circuit for driving the light source device of the present invention.

5A and 5B are a side view and a cross-sectional view schematically showing another example of the light source device of the present invention.

FIG. 6 is a diagram schematically showing another example of the light source device of the present invention.

7A and 7B are cross-sectional views of the light source device shown in FIG. 6, respectively.

8A and 8B are cross-sectional views showing another example of the diffusion plate used in the light source device of the present invention.

9 (A) and 9 (B) are cross-sectional views showing another example of a supporting member used in the light source device of the present invention.

FIG. 10 is a diagram schematically showing another example of the light source device of the present invention.

11A and 11B are a side view and a cross-sectional view, respectively, showing an example of a first electrode formed outside the arc tube.

12A to 12D are diagrams showing a method of connecting a first electrode formed outside the arc tube to a circuit, respectively.

FIG. 13 is a diagram schematically showing another example of the light source device of the present invention.

FIG. 14 is a diagram schematically showing another example of the light source device of the present invention.

FIG. 15 is a diagram schematically showing another example of the light source device of the present invention.

FIG. 16 is a diagram schematically showing another example of the light source device of the present invention.

17 is a sectional view of an example of a liquid crystal display device using the light source device shown in FIG.

FIG. 18 is a diagram schematically showing another example of the light source device of the present invention.

19 is a cross-sectional view of an example of a liquid crystal display device using the light source device shown in FIG.

FIG. 20 is a diagram schematically showing another example of the light source device of the present invention.

21 is a cross-sectional view of an example of a liquid crystal display device using the light source device shown in FIG.

[Explanation of symbols]

10, 10a, 60, 100, 130, 140, 15
0, 160, 180, 200 Light source device 13 Lighting circuit 20, 151a, 151b, 151c Arc tube 20a Tube 20b Dielectric layer 21, 111 First electrode 21a Metal electrode 21b Dielectric layer 22, 52, 72, 162, 182 , 202 second electrode 22P contact portion 23 phosphor layer 53, 143, 203 third electrode 61 support plate 61a groove 62 diffuser plate 63 support member 72a linear electrode 151 arc tube group 161 light guide plate 164 reflective layer 170 liquid crystal panel

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G02F 1/13357 F21Y 103: 00 // F21Y 103: 00 F21S 1/00 E (72) Inventor Nobuhiro Shimizu Osaka 1006, Kadoma, Kadoma, Fuchu, Matsushita Electric Industrial Co., Ltd. F term (reference) 2H091 FA41Z FA42Z FA43Z LA16 LA18 3K013 AA03 BA02 CA02 CA06 CA07 EA03 EA13

Claims (19)

[Claims] 1. At least one arc tube, a discharge medium sealed inside the arc tube, and first and second electrodes for exciting the discharge medium, wherein the first electrode is A light source that is disposed inside or outside the arc tube and in which the second electrode is in contact with the outer surface of the arc tube at a plurality of discontinuous contact portions that are different in distance from the first electrode. apparatus. 2. The light source device according to claim 1, wherein the plurality of contact portions are arranged along a direction of a tube axis of the arc tube. 3. The first electrode is formed at an end portion of the arc tube, and a distance between the contact portions adjacent to each other in the tube axial direction of the arc tube becomes narrower as the distance from the first electrode increases. The light source device according to claim 2. 4. The light source device according to claim 1, wherein the surface of the first electrode is covered with a dielectric. 5. The light source device according to claim 1, further comprising a phosphor layer formed on an inner surface of the arc tube. 6. The light source device according to claim 1, wherein the arc tube includes a glass tube and a dielectric layer formed on an outer surface of the glass tube. 7. The light source device according to claim 1, wherein the second electrode is in contact with the arc tube via a dielectric. 8. The light source device according to claim 1, wherein the discharge medium contains xenon gas. 9. The light source device according to claim 8, wherein the discharge medium further contains mercury. 10. The light source device according to claim 1, wherein the discharge medium does not contain mercury. 11. The light source device according to claim 1, further comprising a support plate, wherein the arc tube is disposed on a side surface of the support plate. 12. The light source device according to claim 11, wherein the support plate takes in light emitted from the arc tube and emits the light from one main surface of the support plate. 13. A support plate and a plurality of the arc tubes supported by the support plate, wherein the second electrode includes a plurality of linear electrodes arranged in parallel, and the arc tube includes the line. The light source device according to any one of claims 1 to 10, wherein the light source device is arranged so as to be orthogonal to the strip electrodes. 14. The arc tube includes a plurality of first arc tubes, a plurality of second arc tubes, and a plurality of third arc tubes, wherein the first, second and third arc tubes are The light source device according to any one of claims 1 to 10, wherein the first, second, and third arc tubes are repeatedly arranged in this order, and emit light of different wavelengths. 15. The apparatus further comprises a third electrode disposed on or around the inner surface of the arc tube, wherein the third electrode is linearly formed so as to be parallel to the tube axis of the arc tube. , The potential E1 of the first electrode and the potential E1 of the second electrode
2 and the potential E3 of the third electrode are | E2 | ≦ | E
11. The light source device according to claim 1, wherein the relationship of 3 | <| E1 | and 0 ≦ E1 · E3 is satisfied. 16. The light source device according to claim 15, wherein both ends of the third electrode are connected to the second electrode at two contact portions selected from a plurality of the contact portions. 17. A liquid crystal display comprising a light source device and a liquid crystal panel through which light emitted from the light source device is transmitted, wherein the light source device is the light source device according to any one of claims 1 to 16. A liquid crystal display characterized by that. 18. The light source device further comprises a light guide plate that takes in light emitted from the arc tube and emits the light from one main surface, and the liquid crystal panel is arranged so as to face the light guide plate. Item 17. The liquid crystal display according to item 17. 19. The light source device includes a support plate and a plurality of the arc tubes supported by the support plate, the second electrode includes a plurality of linear electrodes arranged in parallel, The liquid crystal display according to claim 17, wherein the arc tube is arranged so as to be orthogonal to the linear electrodes.