JP2003223868A - Light source device and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device and a liquid crystal display device which realizes luminescence of high, good luminance distribution, and easy manufacturing. <P>SOLUTION: The light source device or the liquid crystal display device is provided with at least one luminescence tube 20, a discharge medium which is sealed in the luminescence tube 20, and the first and the second electrodes 21 and 22 for exciting the discharge medium. The first electrode 21 is disposed inside the luminescence tube 20 or outside it. The second electrodes 22 contact with outer surface of the luminescence tube 20 at a plurality of discrete contacting areas which are situated at different distances from the first electrode 21. At least one gas chosen from argon gas or krypton gas, and xenon gas of 60 to 80 vol.%, are sealed in the luminescence tube 20. <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 and a liquid crystal display device 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, Patent Document 4 (US Patent)
No. 5,604,410) includes a discharge 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 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 in the arc tube, and first and second electrodes for exciting the discharge medium.
Electrode is disposed inside or outside the arc tube, and the second electrode contacts the outer surface of the arc tube at a plurality of discontinuous contact portions having different distances from the first electrode. The arc tube is filled with a mixed gas containing at least one gas selected from argon gas and krypton gas and xenon gas in the range of 60% by volume to 80% by volume. . According to this light source device, high-luminance light emission with uniform luminance distribution can be obtained.

In the above light source device, the mixed gas may be composed of argon gas and xenon gas.

In the above light source device, it is preferable that the discharge medium does not contain mercury.

In the above light source device, the pressure of the mixed gas may be in the range of 13 kPa to 36 kPa.

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.

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

In the above light source device, the arc tube may include a glass tube and a dielectric layer formed on the 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.

The light source device may further include a support plate, and the arc tube may be disposed on a side surface of the support plate.
In this case, the support plate may take in the light emitted from the arc tube and emit the light from one main surface of the support plate.

The light source device comprises a support plate and a plurality of the arc tubes arranged on the support plate, and the second electrodes are arranged on the support plate so as to be parallel to each other. The arc tube may include a plurality of linear electrodes, and the arc tube may be arranged so as to be orthogonal to the linear electrodes.

Further, the liquid crystal display device of the present invention is a liquid crystal display device including 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 comprises:
It is the above-mentioned light source device of the present invention.

[0024]

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 parts may be given the same parts, and duplicate descriptions 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 20b, 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 mm.
It is about mm. Further, the distance between the outer surface and the inner surface of the glass tube, that is, the wall thickness of the glass tube (wall thickness)
ess) is usually about 0.2 mm to 1.0 mm. When the dielectric layer is formed on the surface of the glass tube, the thickness of the dielectric layer is usually about 0.5 μm to 100 μm. The arc tube 20 is not limited to the linear shape and may have another shape. 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 same applies to the following embodiments). The discharge medium contains at least xenon. The arc tube 20 is filled with at least one gas selected from argon gas and krypton gas and xenon gas. The proportion of xenon gas in the gas sealed in the arc tube 20 is in the range of 60% by volume to 80% by volume. The gas other than xenon is in the range of 40% by volume to 20% by volume, and argon gas, krypton gas, or a mixed gas of argon gas and krypton gas can be used. For example, the gas contained in the arc tube 20 is a mixed gas of xenon gas (60% by volume to 80% by volume) and argon gas (40% by volume to 20% by volume), xenon gas (60% by volume).
Volume% to 80 volume% and krypton gas (40 volume% to
20% by volume, mixed gas, xenon gas (60% by volume)
Mixed gas of argon gas and krypton gas can be used. The gas sealed in the arc tube 20 may slightly contain a gas other than the rare gas (for example, a rare gas). However, from the environmental point of view, it is preferable that the discharge medium does not contain mercury.

The pressure of the gas enclosed in the arc tube 20,
That is, the pressure inside the arc tube 20 is 13 kPa to 36 kPa.
It is preferably in the range of kPa, and 17 kPa to 28
The range of kPa is more preferable. The type and pressure of the gas sealed in the arc tube 20 are the same in the light source devices 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 includes a plurality of electrodes 22a which are in contact with the outside of the arc tube 20. Each electrode 2
2a is connected by wiring. The electrode 22a can be formed of a conductive material. For example, the electrode 22a may be formed of a metal such as copper, aluminum or phosphor bronze,
You may form with the metal paste containing a metal powder (for example, silver powder) and resin. The second electrode described below can be formed of the same material. The second electrode 22 is the first electrode 2
A plurality of discontinuous portions (contact portions) having different distances from 1 are in contact with the outer surface of the arc tube 20.

A sectional view taken along 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 interval between the two contact portions 22P adjacent to each other in the tube axis direction is preferably larger than the wall 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 wall 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.

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 is, for example, a rectangular wave, and its polarity may or may not change. An example of the applied voltage is shown in FIG. Figure 3 (A)
In the example shown in, the applied voltage to the first electrode 21 is 0
It is modulated between a volt and a positive voltage V1. Voltage V
The ratio of the time T1 for applying 1 to the period T2 of the rectangular wave (T1
The value of / T2) is preferably about 0.15 to 0.5. The frequency of the rectangular wave is, for example, 10 kHz.
Is in the range of -60 kHz. 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. The lighting circuit can be simplified when a rectangular wave whose polarity changes is applied.

In the light source device 10, since the second electrode 22 is discontinuously in contact with the arc tube 20, it is possible to prevent 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,
The brightness can be improved as compared with the conventional light source device to which the same electric power is input. 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.

Embodiment 2 In Embodiment 2, another example of the light source device of the present invention will be described. The configuration of the light source device 50 of the second embodiment is schematically shown in FIG. A cross-sectional view taken along line VIA-VIA in FIG. 5 is shown in FIG. 6A, and a cross-sectional view taken along line VIB-VIB in FIG. 5 is shown in FIG. 6B. In addition,
In FIG. 5, the illustration of the diffusion plate is omitted. In addition, FIG.
In (A) and 6 (B), illustration of the phosphor layer is omitted. Further, in FIGS. 5, 6 (A) and 6 (B), the arc tube at the right end is not shown.

The light source device 50 includes a support plate 51 and a diffusion plate 5.
2, the arc tube 20, the first electrode 21 arranged inside the arc tube 20, and the second electrode 62 arranged outside the arc tube 20. The second electrode 62 is connected (grounded) to the ground. First electrode 21 and second electrode 62
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.

A groove 51a having a V-shaped cross section in which the arc tube 20 is arranged is formed in the support plate 51. Arc tube 20
Are fixed to the support plate 51 by support members 53. The support plate 51 can be formed of resin, metal (for example, aluminum), or the like. The surface of the support plate 51 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 62 can be secured, the support plate 51
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 51, the support plate 51 is made of transparent resin or glass. The shape of the support plate 51 is not limited and is determined according to the application.

The diffusion plate 52 is arranged so as to face the support plate 51 with the arc tube 20 interposed therebetween. The diffusion plate 52 is
It is arranged to uniformly diffuse the light emitted from the arc tube 20. The diffusion plate 52 is formed of glass or translucent resin.

A plurality of arc tubes 20 are arranged in parallel on the support plate 51. The number of arc tubes 20 is not limited. A first electrode 21 is provided inside one end of each arc tube 20.
Are arranged. The arc tube 20 can be easily removed from the support member 53.

The second electrode 62 comprises a plurality of linear electrodes 62a formed on the support plate 51. Multiple linear electrodes 6
2a is connected by a wire and is connected to the lighting circuit 13. As shown in FIG. 5, the second electrode 62 is preferably connected to the ground. The arc tube 20 can be safely replaced by connecting the second electrode 62 to the ground. The plurality of linear electrodes 62a are arranged in stripes so as to be parallel to each other. Each linear electrode 62a
Are formed so as to be orthogonal to the central axis of the arc tube 20. The linear electrode 62a can be formed of, for example, a metal paste (for example, silver paste) or a metal film. Further, the linear electrode 62a may be formed of a conductive resin. In this case, the support plate 51 made of resin and the linear electrode 6 made of resin
2a can be integrally molded.

If the distance between the linear electrodes 62a is constant, the brightness may decrease as the distance from the first electrode 21 increases. Therefore, as shown in FIG. 5, the distance between the adjacent linear electrodes 62a 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 62a may be increased. With such a configuration, uniform light emission can be easily obtained. On the other hand, if the widths and intervals of the linear electrodes 62a are constant, manufacturing becomes easy. Particularly, in the light source device of the present invention, the arc tube 2
Since the composition and pressure of the gas sealed in 0 are limited, it is easy to obtain light emission with a uniform luminance distribution even if the width and interval of the linear electrodes 62a are constant.

As shown in FIG. 6A, the linear electrode 62a is formed.
Contacts the arc tube 20 at the groove 51a. That is, the second electrode 62 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 50, the first electrode 21 and the second electrode 21
A discharge is generated by applying a voltage between the electrode 62 and the electrode 62, 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 52. In this way, the light source device 50
Functions as a surface light source.

FIG. 7 shows the result of examining the relationship between the composition and pressure of the enclosed gas and the brightness using the light source device 50 of the second embodiment. The horizontal axis of FIG. 7 represents the pressure of the gas sealed in the arc tube 20, and the vertical axis represents the relative value of brightness. Further, in the lines a, b, c, d, e, f and g, the enclosed gas is xenon-argon (80 vol%: 20 vol), respectively.
%), Xenon-argon (60 vol%: 40 vol)
%), Xenon-krypton (80 vol%: 20 vo)
1%), xenon-krypton (60 vol%: 40v)
ol%), xenon-neon (80 vol%: 20 vo)
1%), xenon-neon (60 vol%: 40 vol)
%) And xenon 100 vol%.
The arc tube 20 has an inner diameter of 2 mm, an outer diameter of 2.6 mm,
An arc tube having a length of 164 mm was used. Further, the second electrode was formed so that the length of the contact portion in the tube axis direction was 3 mm. Moreover, the interval in the tube axis direction between the adjacent contact portions was set to 1 mm.

As shown in FIG. 7, argon gas / krypton gas and xenon gas (60 vol.% To 80 vol.
%) Is a light source device using a mixed gas (lines a, b, c and d) is a light source device using only xenon gas (line g).
The peak of brightness was higher than that. Then, in the light source devices of the lines b, c, and d, the peak of the brightness was shifted to the high voltage side.

Xenon-neon (80vol%: 20v
The brightness of the light source device (line e) using (ol%) was slightly higher than that of the light source device using only xenon gas (line g). Xenon-neon (60vol%: 40vol
%), The luminance peak was lower than that of the light source device (line g) using only xenon gas.

As described above, xenon (60 vol%-
When a gas containing 80 vol%) and argon and / or krypton (40 vol% to 20 vol%) is enclosed in the arc tube 20, the brightness can be increased. The filling pressure of the gas is higher than that of the light source device (line g) using only xenon gas, and in order to prevent contraction discharge,
13 kPa to 36 kPa (more preferably 17 kPa to
It is preferably in the range of 28 kPa). Filling pressure is 1
If it is 3 kPa or less, the number of xenon atoms that emit ultraviolet light may decrease, and the brightness may decrease. When the filling pressure is 36 kPa or more, the discharge may contract and the brightness may decrease. In addition, the ratio of xenon is 60 vol%
With the above, a sufficient number of xenon atoms that emit ultraviolet rays can be secured. Further, by setting the proportion of xenon to 80 vol% or less, it is possible to suppress an increase in current density during discharge and suppress contraction of discharge.

The reason why the brightness is increased by using the mixed gas of argon gas / krypton gas and xenon gas is not clear, but is presumed as follows.

Xenon (80 vol%) and argon (2
FIG. 8 shows the respective emission spectra of the light source device using a mixed gas of 0 vol%) as the filling gas and the light source device using only xenon as the filling gas.
Here, the phosphor layer was formed of phosphors of three wavelengths. Also,
The pressure of the enclosed gas was 15.6 kPa.

In the graph of FIG. 8, 450 nm to 70 nm
The 0 nm spectrum corresponds to the luminescence generated by the excitation of the phosphor layer by the UV radiation generated from the excited fill gas. In addition, the spectrum after 800 nm is
It corresponds to the emission of xenon.

As shown in FIG. 8, the emission intensities of xenon at 823 nm were almost the same even when the enclosed gas was different. On the other hand, the emission intensity at 828 nm was smaller in the light source device using the mixed gas. Xenon 60v
mixed gas of 40 vol% of argon and 40 vol% of argon, mixed gas of 60 vol% of xenon and 40 vol% of krypton,
Similar results were obtained for a light source device using a mixed gas of 80 vol% xenon and 20 vol% krypton. The high emission spectrum intensity of the phosphor means that the brightness of the light source device is high, and the ultraviolet rays (147 nm and 172n) generated by the excitation of the enclosed gas.
It means that the strength of m) is high. And 800n
spectrum intensity after m (for example, 823 nm or 828)
nm peak) means a reduction in energy loss.

FIG. 9 is a schematic diagram showing the excitation process of xenon. In the light source device using the mixed gas of xenon and argon, the excitation from the metastable state 6s ( ³ P ₁ ) to the high level band shown in FIG. 9 is suppressed, and the surplus energy is used for ultraviolet emission. It is thought that it was done. As a result, it is considered that in this light source device, the emission spectrum intensity of xenon at 828 nm was low and the emission spectrum intensity of the phosphor was high. On the other hand, as shown in FIG.
The emission spectrum intensities of xenon in nm were almost the same because the energy difference from the metastable state 6s ( ³ P ₂ ) to the high level band was large and it was difficult to be excited to the high level band, and thus there was no change. it is conceivable that. If the pressure of the enclosed gas is constant, the amount of xenon should be 60%.
When the content is not more than vol%, the amount of xenon atoms that emit ultraviolet light decreases, so that the brightness decreases.

Although an example of the light source device according to the second embodiment has been described above, the present invention is not limited to the above device. For example, the light source device of the present invention may include two first electrodes 21 formed at both ends of the arc tube 20.
Further, the first electrode may have a tubular shape and may be arranged outside the arc tube 20. An example of the cylindrical first electrode 101 is shown in FIG. In addition, line XX in FIG.
FIG. 10B is a cross-sectional view taken along the line. First electrode 10
The outer side of 1 is preferably covered with an insulating layer.
The first electrode 101 is arranged so as to cover the end portion of the arc tube 20.

Further, the first electrode may be formed on the support plate 51 similarly to the linear electrode 62a. A plan view of such a light source device 110 is shown in FIG. Light source device 110
Is different from the light source device 50 only in the first electrode 111.
The first electrode 111 can be formed of a metal paste, like the linear electrode 62a.

The light source device of the present invention can also be applied to the backlight of a field sequential type display device. In this case, a plurality of arc tube groups each including an arc tube that emits red light, an arc tube that emits green light, and an arc tube that emits blue light may be arranged on the support plate.

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 of 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 device. In that case, the liquid crystal panel is arranged above the diffusion plate 52.

(Embodiment 3) In Embodiment 3, another example of the light source device of the present invention will be described. FIG. 12 shows the light source device 120 of the third embodiment. Also, line XIII- in FIG.
A sectional view taken along line XIII is shown in FIG. The liquid crystal panel 130 is also shown in FIG.

The light source device 120 shown in FIG.
1, an arc tube 20, a first electrode 21, a second electrode 122, and a reflector 123.

In the light source device 120, the second electrode 122 is arranged between the light guide plate 121 and the arc tube 20. The second electrode 122 can be formed of a metal paste or a conductive resin. The L-shaped arc tube 20 is supported by a support member 53. It is preferable to form a third electrode on the bent portion of the L-shaped arc tube 20. A reflection plate 123 that reflects the light emitted from the arc tube 20 to the light guide plate 121 side is arranged outside the arc tube 20. Light source device 120
When using as a backlight of a liquid crystal display device,
As shown in FIG. 13, the liquid crystal panel 13 is formed on the light guide plate 121.
0 is placed.

The arc tube 20 is arranged on the side surface of the light guide plate 121. The light emitted from the light emitting tube 20 is guided by the light guide plate 121.
Thus, the light is substantially uniformly emitted from the surface 121a of the light guide plate 121. The light guide plate 121 can be formed of, for example, a transparent resin. The back surface 121b of the light guide plate 121 is provided with irregularities in order to make the emitted light uniform. A reflective layer 124 is formed on the back surface 121b. The reflective layer 124 can be formed of, for example, titanium oxide or metal. Further, a diffusion sheet or a lens sheet may be arranged on the surface 121a of the light guide plate 121 depending on the usage situation. Also in the light source device 120, the second electrode 122
Are in contact with the arc tube 20 at a plurality of discontinuous and different distances from the first electrode 21.

The second electrode may be arranged between the arc tube and the reflector. Such a light source device 140
14 schematically shows the structure of the above. Further, a cross-sectional view taken along the line XV-XV is shown in FIG. The liquid crystal panel 130 is also shown in FIG.

In the light source device 140, the second electrode 142 is arranged between the arc tube 20 and the reflection plate 123. The second electrode 142 can be formed with a metal paste or a conductive resin. The L-shaped arc tube 20 is supported by a support member 53. A third electrode 143 is formed on the bent portion of the L-shaped arc tube 20. The reflection plate 123 arranged outside the arc tube 20 reflects the light emitted from the arc tube 20 toward the light guide plate 121 side. When the light source device 200 is used as a backlight of a liquid crystal display device, a liquid crystal panel 130 is arranged on the light guide plate 121 as shown in FIG.

Although the embodiments of the present invention have been described above by way of example, the present invention is not limited to the above embodiments and can be applied to other embodiments based on the technical idea of the present invention. .

[0066]

As described above, according to the light source device of the present invention, 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. is doing. According to this light source device, it is possible to prevent the discharge from being concentrated near the second electrode. Further, in the light source device of the present invention, high brightness can be obtained by specifying the gas to be sealed in the arc tube. 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.

FIG. 5 is a plan view schematically showing another example of the light source device of the present invention.

6A and 6B are cross-sectional views of the light source device shown in FIG. 5, respectively.

7 is a graph showing the relationship between the pressure of the enclosed gas and the relative brightness of the light source device shown in FIG.

FIG. 8 is a graph showing an example of an emission spectrum of a light source device with a different enclosed gas.

FIG. 9 is a diagram schematically showing an excitation process of xenon.

10A is a plan view showing another example of the first electrode, and FIG. 10B is a sectional view thereof.

FIG. 11 is a plan view schematically showing another example of the light source device of the present invention.

FIG. 12 is a plan view schematically showing still another example of the light source device of the present invention.

13 is a cross-sectional view of the light source device shown in FIG.

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

15 is a cross-sectional view of the light source device shown in FIG.

[Explanation of symbols]

10, 50, 110, 120, 140 Light source device 13 Lighting circuit 20 arc tube 20a tube 20b dielectric layer 21, 101, 111 First electrode 21a metal electrode 21b Dielectric layer 22, 62, 122, 142 Second electrode 22P contact part 23 Phosphor layer 143 Third electrode 51 support plate 51a groove 52 Diffuser 53 Support member 62a linear electrode 121 Light guide plate 123 Reflector 124 reflective layer 130 LCD panel

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigeta Lighting             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd.

Claims (14)

[Claims] 1. At least one arc tube, a discharge medium enclosed in the arc tube, and first and second electrodes for exciting the discharge medium, wherein the first electrode is the light emission. The second electrode is arranged inside or outside of a tube, and the second electrode is in contact with the outer surface of the arc tube at a plurality of discontinuous contact portions having different distances from the first electrode, The tube contains at least one gas selected from argon gas and krypton gas, and 60% by volume to 80% by volume.
A light source device characterized in that a mixed gas containing xenon gas in a volume range is filled. 2. The light source device according to claim 1, wherein the mixed gas comprises argon gas and xenon gas. 3. The discharge medium does not contain mercury.
The light source device according to. 4. The pressure of the mixed gas is 13 kPa-3.
The light source device according to claim 1, wherein the light source device has a range of 6 kPa. 5. 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. 6. The light source device according to claim 1, further comprising a phosphor layer formed on the inner surface of the arc tube. 7. 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. 8. The light source device according to claim 1, wherein the second electrode is in contact with the arc tube via a dielectric. 9. 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. 10. The light source device according to claim 9, wherein the support plate takes in light emitted from the arc tube and emits the light from one main surface of the support plate. 11. A support plate and a plurality of the arc tubes arranged on the support plate, wherein the second electrodes are arranged on the support plate so as to be parallel to each other. The light source device according to claim 1, further comprising a linear electrode, wherein the arc tube is arranged so as to be orthogonal to the linear electrode. 12. A liquid crystal display device 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 at least one arc tube and is enclosed in the arc tube. A discharge medium and first and second electrodes for exciting the discharge medium, wherein the first electrode is disposed inside or outside the arc tube, and the second electrode is A plurality of discontinuous contact portions having different distances from the first electrode are in contact with the outer surface of the arc tube, and the arc tube contains at least one gas selected from argon gas and krypton gas; Volume% to 80
A liquid crystal display device, wherein a mixed gas containing xenon gas in a volume range is filled. 13. The light source device further includes 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 13. The liquid crystal display device according to item 12. 14. The light source device comprises 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 device according to claim 12, wherein the arc tube is arranged so as to be orthogonal to the linear electrodes.