KR20070080415A - Back light unit using light pipe and liquid crystal display having the same - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) comprising the same are provided to selectively remove a light guiding plate and a diffusing plate and increase the efficiency of light, by forming a light source part using a light pipe functioning as the light guiding plate and the diffusing plate. A backlight unit comprises a plurality of light source parts(P) disposed at the rear of an LCD panel. The light source parts are disposed adjacently to each other in one direction. Each of the light source parts includes a lamp(102) for generating light, and a hollow light pipe(101) disposed outside the lamp. The light pipe emits and diffuses the light generated from the lamp. The light pipe has an optical film(103) for totally reflecting a light incident at an angle more than the critical angle and outputting a light incident at an angle less than the critical angle, wherein the optical film has one surface structured.

Description

BACK LIGHT UNIT USING LIGHT PIPE AND LIQUID CRYSTAL DISPLAY HAVING THE SAME}

1A is a cross-sectional view illustrating an example of a backlight unit for illuminating a liquid crystal panel from a back side, and illustrates a direct backlight unit.

FIG. 1B is a cross-sectional view showing another example of a backlight unit for illuminating the liquid crystal panel from the back, and shows an edge-lighted backlight unit.

2A is a cross-sectional view illustrating an embodiment of a liquid crystal display device having a backlight unit of the present invention.

FIG. 2B is a cross-sectional view illustrating an embodiment of the liquid crystal panel of FIG. 2A.

3A-3C are cross-sectional views of other embodiments of the light pipe of FIG. 2A.

The present invention relates to a backlight unit used to illuminate a liquid crystal panel from a back side, and more specifically, by constructing a light source unit using a light pipe, a light guide plate and a diffusion plate included in a conventional backlight unit can be selectively removed. The present invention relates to a backlight unit capable of increasing light efficiency and preventing deformation of an optical sheet due to heat generation, and a liquid crystal display device having the same.

In general, a liquid crystal display device is an electronic device that transmits various electrical information generated by various devices to visual information by using a change in liquid crystal transmittance according to an applied voltage.

Liquid crystal display has been attracting attention as an alternative means to overcome the shortcomings of the CRT (Cathode Ray Tube), which has been widely used since it has the advantages of miniaturization, light weight, low power consumption, etc. Is installed in almost all information processing equipment.

Such liquid crystal displays generally apply a voltage to a liquid crystal having a specific molecular array and change it to another molecular array, and optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal generated by the change of the molecular array. It is a display device that converts the change of the light into a visual change and uses modulation of light by liquid crystal.

A liquid crystal display device, which is a light-receiving element without a self-luminous source, requires a separate light source device capable of illuminating the entire screen of the device from the back side. Such an illumination device for a liquid crystal display device is commonly referred to as a backlight unit.

In general, the backlight unit is classified into an edge-light method and a direct lighting method according to a method of disposing a light emitting lamp.

The edge-light method is a method in which a light emitting lamp is disposed on a side of a light guide plate for guiding light generated from a light emitting lamp, and is applied to a comparatively small liquid crystal display device such as a desktop computer or a laptop monitor. It is good, excellent in durability, and advantageous for thinning the device. On the other hand, the direct method has been developed for use in medium and large display devices of 20 inches or more, and a method of directly illuminating the front of the liquid crystal panel by arranging a plurality of lamp light sources under the liquid crystal panel.

1A is a cross-sectional view illustrating an example of a backlight unit for illuminating a liquid crystal panel from a back side, and illustrates a direct backlight unit.

Referring to FIG. 1A, the backlight unit 10 includes a light source 11, a light source reflector 12, a transparent acrylic plate 14, and an optical sheet 15.

As the light source 11, a cold cathode fluorescent lamp (hereinafter referred to as “CCFL”) capable of generating light of a predetermined wavelength may be used, and the light source 11 is accommodated in the light source reflector 12. do.

The light source reflector 12 is positioned below the light source 11 and reflects the light emitted from the light source 11 in the direction of the liquid crystal panel (not shown) disposed on the light source 11.

The transparent acrylic plate 14 has a predetermined pattern formed therein and serves to remove radiation of light generated from the light source 11. The transparent acrylic plate 14 is typically formed of polymethyl methacrylate (PMMA).

The optical sheet 15 includes a diffusion sheet 15a, a prism sheet 15b and a protective sheet 15c.

The light passing through the transparent acrylic plate 14 is incident on the diffusion sheet 15a, and the diffusion sheet 15a diffuses or condenses the incident light to make the luminance uniform and widen the viewing angle.

On the other hand, the light passing through the diffusion sheet 15a is sharply lowered in brightness, the prism sheet 15b is used to compensate for this. Since the prism sheet 15b refracts the light emitted from the diffusion sheet 15a and concentrates the light incident at a low angle toward the front side, the luminance increases in the effective viewing angle range.

The protective sheet 15c is positioned on the prism sheet 15b to prevent scratches of the prism sheet 15b and to re-expand the viewing angle reduced by the prism sheet 15b within a predetermined range.

In the direct type backlight unit having the above structure, there is a problem that the light efficiency is lowered due to the transparent acrylic plate 14 disposed between the light source 11 and the optical film 15. In addition, when a plurality of CCFLs are disposed adjacent to each other as in the related art, heat convection occurs in a limited space of the liquid crystal display device, thereby deforming the optical sheet 15 disposed thereon, and furthermore, the display quality of the liquid crystal display device. Will adversely affect.

FIG. 1B is a cross-sectional view showing another example of a backlight unit for illuminating the liquid crystal panel from the back, and shows an edge-lighted backlight unit.

Referring to FIG. 1B, the backlight unit 20 includes a light source 21, a light source reflecting plate 22, a light guide plate 26, a reflecting sheet 23, and an optical sheet 25.

CCFL may be used as the light source 21, and the light source 21 is disposed along the light incident surface disposed on both sides of the light guide plate 26.

The light source reflector 22 is disposed along the outer circumferential surface of the light source 21, and reflects the light generated from the light source 21 toward the light guide plate 26 to improve the efficiency of light incident to the light guide plate 26.

The light guide plate 26 uniforms the incident light incident through the light incident surfaces disposed on both sides, and emits the light through the light exit surface toward the liquid crystal panel (not shown) disposed thereon.

The reflective sheet 23 reflects the light emitted to the rear surface of the light guide plate 26 back toward the light guide plate 26 to improve the light efficiency.

The optical sheet 25 includes a diffusion sheet 25a, a prism sheet 25b and a protective sheet 25c, which are the diffusion sheet 15a and prism sheet 15b of the optical sheet 15 described with reference to FIG. 1A. ) And protective sheet 15c, respectively. Therefore, these are not repeated.

In the edge-light type backlight unit having the above structure, the light efficiency is not only lowered because the light incident through the light incident surface disposed on one or both sides of the light guide plate 26 is reduced, and the light is also applied to the light guide plate 26 itself. There is a problem that loss occurs.

On the other hand, a linear light source such as CCFL is widely used as a light source for a backlight unit, but in recent years, color reproducibility is being replaced with a light emitting diode (LED) which is superior to CCFL and is more environmentally friendly.

Backlight units using light emitting diodes are disclosed in Korean Patent Laid-Open No. 10-2005-0113419 (L. Philips LCD Co., Ltd.) and Japanese Patent Laid-Open No. 2004-79488 (Fujitsu Ten Co., Ltd.).

Korean Patent Publication No. 10-2005-0113419 uses a light emitting diode that generates colors of red (R), green (G), and blue (B), which extends the lifespan of a light emitting lamp and provides excellent white light. A direct type backlight unit capable of realizing a power supply, comprising: a power printed circuit board having a plurality of light emitting diodes mounted thereon, a light guide plate that is coupled to the power printed circuit board and mixes light generated from a live light emitting diode, and between the light guide plate and a low source circuit board; Disclosed is a backlight unit including a reflective plate interposed therebetween.

Further, Japanese Laid-Open Patent Publication No. 2004-79488 discloses a light guide plate that equalizes and emits light incident from light incidence planes disposed at two opposite edges, and first and second light incidences on the light incidence plane of the light guide plate. And a plurality of light emitting diodes disposed in the first light source along one longitudinal direction of the two opposite edges, and the second light source along the other longitudinal direction of the two opposite edges and simultaneously in the light guide plate. Disclosed is an edge-lighted backlight unit in which a plurality of light emitting diodes are arranged such that an optical axis is different from an optical axis of light incident from the first light source.

Light emitting diodes are more advantageous than CCFLs in that they are more environmentally friendly than CCFLs, have excellent color reproducibility and contrast, and are capable of partial luminance control (adjusting light and dark areas with greater emphasis). However, when a plurality of light emitting diodes are used in the backlight unit, there is a technical problem that excellent heat dissipation is required due to the characteristics of the heat-generating light emitting diodes, and there is a problem that the cost is increased because the components are expensive compared to the CCFL.

The present invention is to solve the problems of the prior art as described above, by constituting the light source using a light pipe that can replace the function of the light guide plate and the diffuser plate to selectively remove the light guide plate and the diffuser plate, increase the light efficiency An object of the present invention is to provide a backlight unit and a liquid crystal display device having the same, which can prevent deformation of the optical sheet due to heat generation.

In order to achieve the above object of the present invention, the backlight unit for illuminating the liquid crystal panel according to an embodiment of the present invention is disposed in one direction adjacent to each other at the rear of the liquid crystal panel, A plurality of light source units for illuminating a front surface, wherein the light source unit comprises: a lamp generating light having a predetermined wavelength; And a hollow light pipe disposed outside the lamp and configured to emit and diffuse light emitted from the lamp to the outside.

Here, the light pipe includes an optical film capable of total reflection of the light generated from the lamp, one surface of the optical film may be structured. In this case, the structured surface may include a plurality of linear prisms disposed adjacent to each other.

The light pipe may further include a reflector capable of reflecting light incident directly from the lamp or totally reflected by the optical film, and the reflector may be disposed inside the optical film, or the optical It may be disposed along the outer circumferential surface of the optical film on the outside of the film.

The light pipe may further include a diffusion layer disposed along an outer circumferential surface of the optical film and capable of diffusing light emitted from the optical film.

The lamp may be a light emitting diode, and the light emitting diode may be disposed at an end of the light pipe.

The lamp may be a CCFL, and the light pipe may be disposed along an outer circumferential surface of the fluorescent lamp outside the CCFL.

On the other hand, the liquid crystal display device according to an embodiment of the present invention, a pair of substrates facing each other; A liquid crystal layer interposed between the pair of substrates; And a plurality of electrode layers formed on opposite surfaces of the pair of substrates, the plurality of electrode layers for supplying a signal for controlling the alignment of the liquid crystal layer. And a backlight unit for illuminating the liquid crystal panel from the rear. The backlight unit may include a plurality of light source units disposed adjacent to each other at the rear of the liquid crystal panel to illuminate the front surface of the liquid crystal panel, wherein the light source unit may include a lamp to generate light having a predetermined wavelength; And a hollow light pipe disposed outside the lamp and configured to emit and diffuse light emitted from the lamp to the outside.

Here, the light pipe includes an optical film capable of total reflection of the light generated from the lamp, one surface of the optical film may be structured. In this case, the structured surface may include a plurality of linear prisms disposed adjacent to each other.

The light pipe may further include a reflector capable of reflecting light incident directly from the lamp or totally reflected by the optical film, and the reflector may be disposed inside the optical film, or the optical It may be disposed along the outer circumferential surface of the optical film on the outside of the film.

The light pipe may further include a diffusion layer disposed along an outer circumferential surface of the optical film and capable of diffusing light emitted from the optical film.

The lamp may be a light emitting diode, and the light emitting diode may be disposed at an end of the light pipe.

The lamp may be a CCFL, and the light pipe may be disposed along an outer circumferential surface of the fluorescent lamp outside the CCFL.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the present invention.

2A is a cross-sectional view showing an embodiment of a liquid crystal display device having a backlight unit of the present invention, and FIG. 2B is a cross-sectional view showing an embodiment of the liquid crystal panel of FIG. 2A.

2A and 2B, a liquid crystal display according to an exemplary embodiment of the present invention includes a liquid crystal panel 110 for displaying an image according to a driving signal and a data signal applied from the outside, and an upper and a lower portion of the liquid crystal panel. A pair of polarizing films 111 and 111 disposed in the liquid crystal display panel and a backlight unit 100 disposed under the liquid crystal panel to illuminate the liquid crystal panel 110.

The liquid crystal panel 110 includes a lower glass substrate 110a and an upper glass substrate 100b, a color filter 112, a black matrix 117, a pixel electrode 114, a common electrode 115, a liquid crystal layer 116, and TFT array 113 is included.

The color filter 112 includes color filters corresponding to red (R), green (G), and blue (B), and when light is applied, generates the image corresponding to the color of red, green, or blue.

The TFT array 113 switches the pixel electrode 114 as a switching element.

The common electrode 115 and the pixel electrode 114 convert an array of molecules of the liquid crystal layer 116 according to a predetermined voltage applied from the outside.

The liquid crystal layer 116 is composed of a plurality of liquid crystal molecules, and the liquid crystal molecules change an arrangement in accordance with a voltage difference generated between the pixel electrode 114 and the common electrode 115, whereby the backlight unit ( Light provided from 100 is incident on the color filter 112 in response to a change in the molecular arrangement of the liquid crystal layer 116.

The backlight unit 100 is positioned under the liquid crystal panel 110 and provides light, for example, white light, to the liquid crystal panel 110.

The backlight unit 100 includes a plurality of light source units P disposed adjacent to each other and a bottom chassis 107 for accommodating the plurality of light source units P, and includes an inner wall of the bottom chassis 107. Between the light source unit P disposed at the outermost portion, a reflective member 106 capable of reflecting light generated from the light source unit P may be disposed.

In one embodiment of the present invention, the backlight unit 100 is a direct method in which the light source unit P is disposed under the liquid crystal panel 110.

The light source unit P includes a lamp 102 for generating light of a predetermined wavelength.

The outer side of the lamp 102 includes a hollow light pipe 101 provided with an inner space for accommodating the lamp 102. The light pipe 101 is a tubular optical member having at least the same length as one side of the liquid crystal panel 110.

Lamp 102 according to an embodiment of the present invention is a light emitting diode (LED). In this case, the lamp 102 may be disposed at either end of the light pipe 101 or may be disposed opposite to both ends.

When the light emitting diode 102 is disposed only at one end of the light pipe 101, the light emitting diode 102 is provided with reflecting means capable of reflecting light on the other end to be generated from the light emitting diode 102 and transmitted to the end of the light pipe 101. It is desirable to be able to reuse the light that is being used. In addition, in order to uniformize the light emitted from the light pipe 101, it is preferable to design the taper to decrease the cross-sectional area of the light pipe 101 from one end of the light emitting diode 102 to the other end of the opposite side.

By arranging the light emitting diode 102 at the end of the light pipe 101 according to an embodiment of the present invention, it is not only possible to utilize the light emitting diode 102 as a point light source as a linear light source equivalent to a CCFL, but also a backlight unit. The number of light emitting diodes used in the 100 can be significantly reduced as compared with the related art.

The light emitting diode 102 used in the backlight unit 100 according to an embodiment of the present invention is not limited, and one white light emitting diode may be used, or red (R), green (G), and blue (B) may be used. It is also possible to use a combination of three light emitting diodes that generate color.

Lamp 102 according to another embodiment of the present invention is a CCFL. In this case, the CCFL 102 has a predetermined length suitable for illuminating the front surface of the liquid crystal panel 110, and the light pipe 101 accommodating the CCFL 102 therein has at least the same length as the CCFL 102.

Light pipe 101 according to an embodiment of the present invention is a hollow tubular optical waveguide is an optical film designed to continuously totally reflect the light incident below the critical angle, and to emit light incident from above the critical angle to the outside (103). The critical angle can be defined as the arc sine of the ratio of the refractive index of the surrounding medium, for example air, to the optical film 103 to the refractive index of the material constituting the optical film 12, which is a person skilled in the art. Would be understandable without further explanation.

The optical film 103 is generally manufactured from a transparent acrylic resin such as polymethyl methacrylate (Poly Methyl Meta Acrylate), and may be obtained by forming a hollow tubular shape after structuring one surface as described below. Polymethacrylates are high in strength and therefore not easily broken and easily deformed. In addition, the visible light transmittance is high, making it suitable as a light source material.

The optical film 103 is structured on one surface 103a, and the other surface opposite thereto is an unstructured film, which can be obtained by forming a plurality of linear prisms disposed adjacent to the base.

In the embodiment shown in FIG. 2A, the structured face 103a is designed to face the inside of the light pipe 101, but if necessary, the structured face 103a faces the outside of the light pipe 101. It is also possible to design.

A diffusion layer 105 is disposed on an outer surface of the optical film 103, and the diffusion layer 105 emits light incident through the optical film 103 to the outside, and simultaneously scatters it to be emitted through the light pipe 101. Equalizes light The diffusion layer 105 may be used without limitation as long as the layer has a function of diffusing light, and is obtained by, for example, dispersing acrylic beads in a resin and placing the film solidified outside the optical film 103. Can be.

The light pipe 101 may include a reflector 104 to assist in reflecting light emitted from the lamp 102 and emitting it out of the light pipe 101.

Reflector 104 according to one embodiment of the present invention is disposed on the structured surface 103a of optical film 103 between lamp 102 and optical film 103, as shown The light incident directly from 102 or totally reflected by the optical film 103 is reflected so that the light is reincident to the optical film 103 above the critical angle. Light reincident to the optical film 103 above the critical angle is emitted through the optical film without total reflection at the surface. The reflector 104 is made of a highly reflective material, for example, can be obtained by coating silver (Ag) on the surface.

3A-3C are cross-sectional views of other embodiments of the light pipe of FIG. 2A. However, it will be described based on the structural differences from the light pipe shown in FIG. 2A.

Referring to FIG. 3A, a light pipe 201 according to another embodiment of the present invention is a hollow tubular optical waveguide that continuously reflects light incident at a critical angle or less, and light incident at or above a critical angle emits light to the outside. And an optical film 203 designed to be made.

The optical film 203 may have a structured surface 203a in which a plurality of linear prisms are disposed, which is disposed toward the inside of the light pipe 201.

The diffusion layer 205 is disposed outside the optical film 203, and the diffusion layer 205 emits light incident through the optical film 203 to the outside, and simultaneously scatters it to radiate through the light pipe 201. Equalizes light

The light pipe 201 includes a reflector 204 capable of reflecting light exiting out of the light pipe 201, the reflector 204 being disposed along the outer circumferential surface of the diffusion layer 205, as shown. do. The diffusion layer 205 increases the light efficiency by injecting light emitted in a direction opposite to the direction in which the liquid crystal panel (not shown) is positioned to the inside of the light pipe 201.

Referring to FIG. 3B, the light pipe 301 according to another embodiment of the present invention is a hollow tubular optical waveguide that continuously reflects light incident below a critical angle, and light incident above the critical angle emits light to the outside. And an optical film 303 designed to be able to exit.

The optical film 303 may have a structured surface 303a in which a plurality of linear prisms are disposed, which is disposed toward the inside of the light pipe 301.

In the present embodiment, both the reflector 304 and the diffusion layer 305 are disposed on the outer circumferential surface of the optical film 303. However, the diffusion layer 305 for diffusing the light emitted through the light pipe 301 is disposed toward the liquid crystal panel (not shown), and reflects the light emitted through the optical film 303 to re-inject. Reflector 304 is disposed opposite diffusion layer 305.

Referring to FIG. 3C, the light pipe 401 according to another embodiment of the present invention is a hollow tubular optical waveguide, and continuously reflects light incident at a critical angle or less, and light incident at or above a critical angle emits light to the outside. And an optical film 403 designed to be able to exit.

The optical film 403 may have a structured face 403a in which a plurality of linear prisms are disposed, the structured face being disposed toward the inside of the light pipe 401. In at least a portion of the structured face 403a in this embodiment, no structure, such as a linear prism, is formed.

Where the structure is not formed, the light incident directly from a lamp (not shown) or totally reflected from the optical film 403 reflects the incident light to assist the light to be emitted in the direction in which the liquid crystal panel (not shown) is arranged. Reflector 404 may be disposed.

A diffusion layer 405 is disposed on the outer circumferential surface of the optical film 403 to diffuse light emitted through the optical film 405.

Referring back to FIG. 2A, the backlight unit 100 according to the exemplary embodiment of the present invention includes an optical sheet 108, and the optical sheet 108 is disposed above the light source unit P. Referring to FIG.

The optical sheet 108 includes a diffusion sheet 108a, a prism sheet 108b and a protective sheet 108c.

The light emitted from the light source unit P passes through the diffusion sheet 108a, and the diffusion sheet 108a diffuses or condenses the incident light to make the luminance uniform and widen the viewing angle.

On the other hand, the light passing through the diffusion sheet 108a is sharply lowered in brightness, the prism sheet 108b is used to compensate for this. Since the prism sheet 108b refracts the light emitted from the diffusion sheet 108a and concentrates the light incident at a low angle toward the front side, the luminance increases in the effective viewing angle range.

The protective sheet 108c is located on the prism sheet 108b to prevent scratches of the prism sheet 108b and to re-expand the viewing angle reduced by the prism sheet 108b within a predetermined range.

According to the present invention, by combining a point light source or a linear light source with a light pipe that can replace the functions of the light guide plate and the diffuser plate, the light source unit is configured to remove the light guide plate and the diffuser plate which are normally provided in the liquid crystal display, thereby increasing the light efficiency. There is an advantage.

In addition, since the heat generating light source is a structure housed inside the light pipe, heat generated from the light source is only convection inside the light pipe, and thus heat due to interaction with heat generated from other light sources arranged adjacently. Convection is significantly reduced. Therefore, there is an advantage that the thermal deformation of the optical sheet due to the heat generation of the light source portion can be significantly alleviated.

Claims (18)

A backlight unit for illuminating a liquid crystal panel from the rear, Is disposed in one direction adjacent to each other in the rear of the liquid crystal panel includes a plurality of light source for illuminating the front of the liquid crystal panel, The light source unit, A lamp for generating light of a predetermined wavelength; And And a hollow light pipe disposed outside the lamp and configured to emit and diffuse light emitted from the lamp to the outside. The method of claim 1, The light pipe totally reflects light incident below a critical angle, and light incident above the critical angle includes an optical film designed to emit light to the outside. One surface of the optical film is structured, characterized in that the backlight unit. The method of claim 2, And said structured face has a plurality of linear prism arrays arranged adjacently. The method of claim 2, The light pipe, And a reflector capable of reflecting light incident directly from the lamp or totally reflected from the optical film. The method of claim 4, wherein And the reflector is disposed inside the optical film. The method of claim 4, wherein And the reflector is disposed outside the optical film along an outer circumferential surface of the optical film. The method of claim 2, The light pipe is disposed along an outer circumferential surface of the optical film, the backlight unit further comprises a diffusion layer capable of diffusing light emitted from the optical film. The method of claim 1, The lamp is a light emitting diode, And the light emitting diode is disposed at an end of the light pipe. The method of claim 1, The lamp is a cold cathode fluorescent lamp, And the light pipe is disposed along an outer circumferential surface of the cold cathode fluorescent lamp at an outer side of the cold cathode fluorescent lamp. A pair of substrates opposed to each other; A liquid crystal layer interposed between the pair of substrates; And A liquid crystal panel formed on opposite surfaces of the pair of substrates, the liquid crystal panel including a plurality of electrode layers for supplying a signal for controlling the alignment of the liquid crystal layer; And Including a backlight unit for illuminating the liquid crystal panel from the rear, The backlight unit, Is disposed in one direction adjacent to each other in the rear of the liquid crystal panel includes a plurality of light source for illuminating the front of the liquid crystal panel, The light source unit, A lamp for generating light of a predetermined wavelength; And And a hollow light pipe disposed outside the lamp and configured to emit and diffuse light emitted from the lamp to the outside. The method of claim 10, The light pipe totally reflects light incident below a critical angle, and light incident above the critical angle includes an optical film designed to emit light to the outside. And one surface of the optical film is structured. The method of claim 11, And wherein said structured surface has a plurality of linear prism arrays arranged adjacently. The method of claim 11, The light pipe, And a reflector capable of reflecting light incident directly from the lamp or totally reflected from the optical film. The method of claim 13, And the reflector is disposed inside the optical film. The method of claim 13, And the reflector is disposed outside the optical film along an outer circumferential surface of the optical film. The method of claim 11, The light pipe is disposed along the outer circumferential surface of the optical film, the liquid crystal display device further comprising a diffusion layer capable of diffusing light emitted from the optical film. The method of claim 10, The lamp is a light emitting diode, And the light emitting diode is disposed at an end of the light pipe. The method of claim 10, The lamp is a cold cathode fluorescent lamp, And the light pipe is disposed along an outer circumferential surface of the cold cathode fluorescent lamp at an outer side of the cold cathode fluorescent lamp.

Images