KR20170042964A - Optical Source Unit and Display Device Using the Same - Google Patents

Abstract

The present invention relates to a light source unit employing a band-pass filter film which does not cause material deterioration and which broadens a gamut, and which solves the light leakage problem, and a display device using the same. In the light source unit of the present invention, And a reflection hologram optical film having a Bragg mirror function is applied for this purpose.

Description

Technical Field [0001] The present invention relates to a light source unit and a display device using the same,

The present invention relates to a display device, and more particularly, to a light source unit employing a band-pass filter film which does not cause material deterioration, and which solves the light leakage problem, and a display device using the same.

Specific examples of the flat panel display include a liquid crystal display (LCD) device, an organic light emitting display device, a plasma display panel (PDP) device, a quantum dot display device ), A field emission display device (FED), and an electrophoretic display device (EPD). The flat display panel, which realizes images in common, is an essential component, The flat panel display panel has a structure in which a pair of transparent insulation substrates are bonded together with inherent light emission, polarization, or other optical material layers interposed therebetween.

Among them, the light-receiving display panel such as the liquid crystal display device does not emit light itself, and necessarily uses the light source unit attached to one side. In particular, the backlight unit is referred to as being positioned below the light-receiving display panel. In this case, the light emitted from the backlight passes through the transparent electrode (pixel electrode, common electrode) in the display panel to display information, It is possible to provide the image to the viewer.

On the other hand, a general backlight unit includes a light guide plate having a light source on one side and a plurality of optical sheets on the light guide plate.

However, the color gamut expressed by the backlight unit developed until now remains in a limited color expression, not so much as to express the natural color.

In addition, efforts have been made to expand the gamut by applying an optical sheet that emits light in the form of photo luminescence using a quantum dot, which is a semiconductor of several nanometers in size, in an optical sheet The optical sheets including the quantum dots are easily oxidized by oxygen, moisture, and heat applied conditions, thereby deteriorating the performance of the optical sheets.

Since the optical sheet including the quantum dots absorbs the light emitted from the light guide plate and emits the secondary light through the omnidirectional angle, there is a problem that light leakage occurs, and there is a problem in applying the light leakage to the backlight unit. A solution was required.

SUMMARY OF THE INVENTION The present invention has been devised to solve the problems described above, and it is an object of the present invention to provide a light source unit employing a bandpass filter film which does not cause material deterioration while expanding gamut, There is a purpose.

According to an aspect of the present invention, there is provided a light source unit including: a light source unit that absorbs light of a specific wavelength and transmits a wavelength of a remaining region band to extend a gamut; A hologram optical film is applied.

For example, the light source unit of the present invention includes a light guide plate, an LED array disposed on one side of the light guide plate, and an LED array disposed on the light guide plate and absorbing a wavelength between red light and green light and a wavelength between green light and red light And a band-pass filter film.

The band-pass filter film preferably has a total reflection characteristic with respect to the wavelength of the absorbed light. To this end, the band-pass filter film may be formed by stacking one or more pairs of insulating layers having a difference in refractive index. In addition, the band-pass filter film may have a repeated refractive index pattern in the form of a horizontal or inclined shape in at least one of the insulating layers in the pair of insulating layers.

For example, the band-pass filter film can absorb a wavelength of 560 nm to 610 nm, or absorb wavelengths of a wavelength of 450 nm to 500 nm.

The band-pass filter film may further include a lens unit for transmitting light emitted from the LED array to the light guide plate as parallel light, between the light guide plate and the LED array. In this case, can do. A plurality of stripe patterns perpendicular to the light traveling direction of the light guide plate may be provided on the surface of the light guide plate.

Alternatively, the light source unit may further include a prism sheet between the light guide plate and the band-pass filter film, and a diffusion plate above the band-pass filter film.

The display device to which the above-described light source unit structure is applied can have the following structure. That is, a cover bottom having a reflective plate on the inside thereof, a light guide plate on the reflection plate in the cover bottom, an LED array disposed on one side of the light guide plate, a prism sheet on the light guide plate, and a prism sheet on the prism sheet, A band-pass filter film for absorbing at least one of a wavelength of red light and a wavelength of red light; and a diffusion plate on the band-pass filter film and a display panel on the diffusion plate.

In addition to the prism sheet and the diffusing plate, the display unit may further include a lens unit for transmitting light emitted from the LED array to the light guide plate as parallel light, between the light guide plate and the LED array.

The light source unit of the present invention and the display device using the light source unit have the following effects.

The HOE film that selectively absorbs light of a specific wavelength is applied to the upper side of the light guide plate to shape the wavelength characteristics of the outgoing light transmitted to the display panel so that the distinction between the primary color light areas can be prominent. This improves the color gamut and allows the color gamut to be expanded.

In addition, the light source unit of the present invention can solve the deterioration problem and the environmental pollution problem of the conventional optical sheet by applying the band-pass filter film to the HOE film without material deterioration due to long-time use.

The light leakage problem caused by the omnidirectional reflection characteristic of the conventional optical sheet can also be solved. Particularly, when the omnidirectional reflection occurs, the bezel area is also increased. In the light source unit of the present invention, the absorbed light is totally reflected in the band-pass filter film and is not reflected to the outside, .

1 is a perspective view showing a light source unit according to a first embodiment of the present invention;
FIGS. 2A and 2B are cross-sectional views showing the structure and function of the band-pass filter film of FIG.
FIG. 3 is a graph showing the transmittance per wavelength according to an example of the band-pass filter film of FIG.
4 is a graph showing a spectrum of incident light and transmitted light when the light source unit of the present invention is applied
5A and 5B are diagrams showing refractive index distributions of light for explaining the principle of spectral deformation of the light source unit of the present invention
6 is a view showing the gamut expansion of the light source unit of the present invention
7 is a perspective view showing a display device to which the light source unit according to the first embodiment of the present invention is applied
8 is a perspective view illustrating a light source unit according to a second embodiment of the present invention.
9 is a sectional view showing a light source unit according to a second embodiment of the present invention
10 is a cross-sectional view showing an example of the structure of the band-pass filter film of FIG. 9
11 is a graph showing the transmittance according to the wavelength of the light source unit of the second embodiment of the present invention
12 is a sectional view showing a display device to which the light source unit according to the second embodiment of the present invention is applied

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, a detailed description of known technologies or configurations related to the present invention will be omitted when it is determined that the gist of the present invention may be unnecessarily obscured. The component names used in the following description are selected in consideration of easiness of specification, and may be different from the parts names of actual products.

l First Embodiment

FIG. 1 is a perspective view showing a light source unit according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a structure and a function of the bandpass filter film of FIG. FIG. 3 is a graph showing the transmittance of the band-pass filter film of FIG. 2 according to an example.

1 and 2, the light source unit 1000 according to the first embodiment of the present invention includes a light guide plate 100, an LED array 120 disposed on one side of the light guide plate 100, , And a bandpass filter (140) for absorbing at least one of a wavelength between red light and green light and a wavelength between green light and red light.

3, the band-pass filter film 140 has an absorption characteristic with respect to a specific wavelength lambda c of light incident from the light guide plate 100 and has a transmission characteristic with respect to the remaining wavelengths lambda a and lambda b . And has a total internal reflection characteristic with respect to the wavelength? C of the absorbed light, and is made of, for example, a holographic optical element (HOE). Particularly, the band-pass filter film 140 has a function of shaping a spectrum of light to be emitted by trapping light having a specific wavelength out of the light to be emitted, The color gamut and the color gamut can be extended.

For example, when the band-pass filter film 140 absorbs light between green light and red light, it absorbs a wavelength of 560 nm to 610 nm, and when absorbing light between blue light and green light, it has a wavelength of 450 nm to 500 nm Can be absorbed. The band-pass filter film 140 may simultaneously absorb light in these two regions, and may absorb only light in one region of the band-pass filter film 140.

The color reproduction ratio is expanded by the following principle. That is, for example, when the band-pass filter film 140 absorbs light having a wavelength of 560 nm to 610 nm between the green light and the red light, when using the same LED light source array, The light emitted from the light source array of the bandpass filter film 140 is uniformly emitted over the entire range of the visible light region. After the application of the bandpass filter film 140, the specific wavelength of 560 nm to 610 nm is absorbed. The green color light and the red color light are remarkably expressed. Therefore, it is possible to obtain an improvement in the color reproduction ratio close to the actual color of the natural world.

As shown in FIG. 2A, the band-pass filter film 140 may be formed by stacking one or more pairs of insulating layers 145a and 145b having different refractive indices n1 and n2 on a transparent substrate 141 145) and a protective film (148) on the stack (145).

The protective film 148 is a transparent film provided to prevent particles such as dust from affecting optical characteristics, and may be omitted as the case may be.

The substrate 141 is used as a surface for forming the stack 145. It is preferable that the substrate 141 is as thin and transparent as possible in terms of the optical surface. However, in order to prevent deformation of the stack 145 during formation, have. Here, when a plurality of pairs of the insulating layers 145a and 145b in the stack 145 are provided, each pair may have the same configuration, and each pair of insulating layers may have the same refractive indexes n1 and n2 and the same thickness.

One of the insulating layers 145a and 145b has a high refractive index n1 and the other has a low refractive index n2. For example, when the first insulating layer 145a has a high refractive index n1, the value of the refractive index may be 1.5 to 2.3, and the value of the refractive index of the second insulating layer 145b of the low refractive index n2 May be 1.0 to 1.5. However, the range of the refractive index is not limited to this, and the band-pass filter film 140 may be formed on the light guide plate 100 in a different refractive index condition . The band-pass filter film 140 has an internal total reflection characteristic only for a specific wavelength. Total reflection occurs at a specific wavelength within the stack 145, and light of the remaining wavelength is transmitted as it is.

A plurality of stacks 145 in the band-pass filter film 140 may be provided to have absorption and total reflection characteristics for two or more wavelengths. In this case, at least one of the refractive index values of the first and second insulating layers of different stacks will be different and preferably the refractive index value of the high refractive index of each stack will be different.

On the other hand, the insulating layers 145a and 145b in the stack 145 of the band-pass filter film 140 have different refractive indices, and the first insulating layer 145a and the second insulating layer 145b in each pair of insulating layers in the stack 145, The thickness of the two insulating layers 145b may be different from each other.

2B, in another embodiment, the band-pass filter film 245 has a repeated refractive index in a horizontal or inclined form in at least one insulating layer 245 in a pair of insulating layer units 2450 Pattern 245a. Here, the refractive index pattern 245a may be located in a long direction in the y-axis direction when the transverse direction in the drawing is referred to as an x-axis and the direction of piercing the sheet is referred to as a y-axis. The refractive index pattern 245a has a high refractive index n1, And another low refractive index (n3) material. For convenience, the insulating layer having the refractive index pattern 245a is referred to as a first insulating layer 245. [

The second insulating layer 244 in the pair of insulating layer units 2450 is made of a material having a refractive index n2 lower than the high refractive index n1 and in this case, The refractive index n3 of the region other than the refractive index pattern 245a of the refractive index pattern 245a.

On the other hand, the pair of insulating layer units 2450 may have the same structure and may have a stacked structure with absorption characteristics of the same wavelength, or may have a plurality of stacks of different kinds of insulating layer units 2450, The band-pass filter film 140 may have a wavelength absorption characteristic.

In addition to the band-pass filter film 140, optical sheets 130 and 150 are provided on the light guide plate 100 to condense and diffuse light. The optical sheets include a prism sheet 130 for outputting light with better light collecting performance from the lower light guide plate 100 and a diffusion plate 150 for diffusing the emitted light upward.

Here, the band-pass filter film 140 is preferably positioned directly above the prism sheet 130 that emits light condensed upward from the light guide plate 100.

Here, the LED array 120 is disposed on one side of the light guide plate 100 having a regular thickness and a predetermined thickness, and supplies light to the light guide plate 100 in a side view . The LED is a light source that supplies white light to the light guide plate 100, and supplies light to the light guide plate 100 over a RGB spectrum based on a specific phosphor.

Meanwhile, the light guide plate 100 includes a reflector (see 170 in FIG. 7) on the lower side and is housed in a cover bottom (see 160 in FIG. 7) together with the LED array 120.

In this case, the light guide plate 100 advances the light incident from the LED array 120 in a plan view and the light transmitted in the lateral direction is reflected by a reflector 170 (FIG. 7) provided at the lower side in the vertical direction To the upper optical sheets (130, 150) and the band-pass filter film (140).

The reason why the band-pass filter film 140 is closest to the prism sheet 130 is that the light-guiding property is best on the prism sheet 130 among the optical sheets. The light having some divergence characteristics among the light emitted from the light guide plate 100 does not have the Bragg mirror characteristics normally in the band-pass filter film 140.

4 is a graph showing the spectra of incident light and transmitted light when the light source unit of the present invention is applied.

FIG. 4 shows a spectrum of incident light and transmitted light when the light source unit of the present invention is applied. For example, when the LED light source used in the LED array 120 is a KSF phosphor, the first peak characteristic of the blue light region And shows transmittance spectra in the case where the band-pass filter film is applied and in the case where the band-pass filter film is applied, when the second peak characteristic is uniformly shown in the green light and red light regions.

That is, when the band-pass filter film is not applied, the transmitted light spectrum shows a spectrum with a slightly weaker intensity than the light source directly emitted from the LED light source, but no change in the second peak characteristic is observed. However, in the case of applying the band-pass filter film of the present invention, it was confirmed that the absorption characteristics of light clearly appear in the region between the green light and the red light, that is, in the wavelength range of 575 nm to 600 nm.

That is, the light source unit of the present invention can improve the color reproduction rate by enhancing the representation of the primary color light adjacent to the wavelength of the mixed color through absorption of the mixed color light region.

FIGS. 5A and 5B are views showing a refractive index distribution of light for explaining the principle of spectral deformation of the light source unit of the present invention, and FIG. 6 is a diagram showing the gamut expansion of the light source unit of the present invention.

FIGS. 5A and 5B are diagrams showing a periodic refractive index distribution before and after passage of a band-pass filter film. It can be seen that a certain wavelength gap occurs when passing through the band-pass filter film. Here, the band of the forbidden wavelength region of light is referred to as a photonic band gap.

Meanwhile, FIG. 6 also shows the color gamut (color gamut) defined by the CIE in 1931 as shown in FIG. 6, and the area within the boundary that appears as a horseshoe is a natural range that can be perceived by a person. The range that can be expressed by the actual display device is limited to the triangular shape therein. However, when the bandpass filter film is applied, the area of the triangular shape can be increased by improving the color reproduction ratio.

7 is a perspective view and a cross-sectional view illustrating a display device to which the light source unit according to the first embodiment of the present invention is applied.

7 shows a display device 2000 to which the light source unit of the present invention described above is applied. Referring to FIG. 7, the cover bottom 170 and the reflection plate 160 provided on the inner side surface of the cover bottom 170 A light guide plate 100 positioned on the reflection plate 160 and received in the cover bottom 170 and a light guide plate 150 disposed on one side of the light guide plate 100 and being accommodated in the cover bottom 170 together with the light guide plate An optical sheet 130 including an LED array 120 and a bandpass filter 140 disposed on the light guide plate 100 and an optical sheet 130 disposed on an upper portion of the light guide plate 100 to support the display panel 200. [ A display panel 200 placed on the guide panel 180 and a case top 190 having an upper edge and a side edge of the display panel 200. The display panel 200 includes a guide panel 180,

Here, the case top 190 and the guide panel 180 are frame-shaped open at least to the active area (display area) of the display panel 200.

In addition, the LED array 120 may be replaced with other types of light sources, such as fluorescent lamps, as the case may be. However, in this case, the region of the absorption wavelength can be shifted and adjusted according to the wavelength spectrum of the light source.

The LED array 120 includes a plurality of LEDs 120a mounted on a PCB substrate 120b so that the incident portion of the LEDs 120a is disposed so that the side surfaces of the light guide plate 100 face each other.

Also, the LED array 120 may be disposed on the lower side of the light guide plate 100 instead of the side.

The cover bottom 160 has a rectangular inner side surface and side surfaces vertically connected to the four sides of the inner side surface, and has a storage space inside the inner side surface and the side surface. The thickness of the side surface of the cover bottom 160 is equal to or greater than the sum of the thicknesses of the light guide plate 100 and the reflection plate 170. The thickness of the light guide plate 100 and the reflection plate 170 ).

The display panel 200 may be a liquid crystal display panel, for example, a liquid crystal display panel. The liquid crystal display panel includes a TFT array substrate 210 opposed to each other, And a color filter substrate 220 and a liquid crystal layer therebetween. The lower and upper portions of the display panel may include polarizing plates 230a and 230b having transmission axes crossing each other. Here, the TFT array substrate and the color filter substrate include a plurality of pixels in a matrix corresponding to the active region (display region), and the TFT array substrate includes a gate line and a data line for crossing the pixels, A pixel electrode provided in an area between the gate line and the data line in each pixel, and a thin film transistor connected to the gate line and the data line. The color filter substrate includes a gate line and a data line, a black matrix layer covering the thin film transistor, and a color filter layer corresponding to each pixel. In addition, a common electrode may be formed over the entire active region of the color filter substrate or may be provided in the TFT array substrate in such a manner that the pixel electrode is alternated with the pixel electrode.

On the other hand, the liquid crystal display panel of the above-mentioned shape is only an example, and each component may be formed on a substrate different from the example shown, and further includes a component such as an inorganic insulating film or an organic insulating film between lines and lines can do.

l Second Embodiment

FIG. 8 is a perspective view illustrating a light source unit according to a second embodiment of the present invention, and FIG. 9 is a cross-sectional view illustrating a light source unit according to a second embodiment of the present invention. 10 is a cross-sectional view showing an example of the structure of the band-pass filter film of FIG.

A light source unit according to a second embodiment of the present invention shows a backlight unit that emits light with directivity.

8 and 9, the light source unit according to the second embodiment of the present invention includes a light guide plate 300, a lens unit 420 on one side of the light guide plate 300, A light incident portion 400 including an LED array 410 regularly arranged with an LED light source 410a having a focal length; and a light incident portion 400 disposed above the light guide plate and having a wavelength between red light and green light and a wavelength between green light and red light, And a bandpass filter 500 that absorbs the wavelength of the light.

The lens unit 420 receives the light from the LED light source 410a of the point light source 410 and receives the incident light according to the focal distance from the LED light source 410a and the curvature of the incident part of the lens unit 420, And extends to a width corresponding to the lens unit 420 to transmit linear light, and the light guide plate 300 functions to output the transmitted linear light in parallel.

The lens unit 420 is not limited to the example shown in the drawing and may extend the light of the LED light source between the LED light source 410a and the light guide plate 300 to the width of the light guide plate 300, If so, it can be changed to other forms.

The lens unit 420 may further include a reflective layer on its upper side to concentrate the transmission of light to the light guide plate 300 in parallel without diverging light toward the upper side. In addition, the lens unit 420 may have the same thickness corresponding to the thickness of the light guide plate 300.

On the upper surface of the light guide plate 300, a plurality of stripe patterns 310 may be formed in a shape perpendicular to the parallel light traveling direction of the light guide plate 300. With the provision of the stripe pattern 310, it is easy to control the outgoing direction of the light emitted from the light guide plate 300.

In the light source unit according to the second embodiment of the present invention, the lens unit 420 is disposed between the light guide plate 300 and the LED array 410 to transmit a constant parallel light to the light guide plate 300, (Not shown) through the band-pass filter film 500 to the display panel (not shown), so that the emitted light has a uniform directivity, Or a privacy display panel, which is useful for a directional device.

In this case, a display panel may be directly provided on the band-pass filter film 500 without an additional optical film. In addition, the band-pass filter film 500 itself may be disposed in contact with the light guide plate 300 to perform selective reflection of the selective light of the parallel light emitted to the image side and total reflection in the band-pass filter film 500.

Here, the structure of the band-pass filter film 500 is the same as the structure described in FIG. 2A or 2B described above, or a stack 545 having at least one insulating layer pair unit so as to maintain the directivity of the outgoing light inclinated in a specific direction, Or a surface grating or volume grating with a constant thickness.

The stack 545 may be formed on a transparent substrate 541 having a constant thickness.

On the other hand, the light source unit of the second embodiment described above may also have the same wavelength-selective characteristics of the outgoing light as in the first embodiment described above.

11 is a graph showing the transmittance according to the wavelength of the light source unit of the second embodiment of the present invention.

In Fig. 11, the band-pass filter film 500 is configured so that the light source unit of the second embodiment has absorption characteristics at a first wavelength lambda c between red light and green light and at a second wavelength lambda d between green light and blue light, And stacking two stacks 545 of different configurations.

Further, the light source unit of the second embodiment of the present invention may have the following configuration.

12 is a cross-sectional view illustrating a display device to which the light source unit according to the second embodiment of the present invention is applied.

12, the display device according to the second embodiment of the present invention includes a cover bottom 170, a reflection plate 160 provided on an inner side surface of the cover bottom 170, A light guide plate 300 positioned on the reflection plate 160 and received in the cover bottom 170 and a light guide plate 300 positioned on one side of the light guide plate 300 and being accommodated in the cover bottom 170 together with the light guide plate 300. [ And a lens unit 420 having a predetermined focal distance with respect to each LED light source 410a constituting the LED array and having a distance from the LED light source 410a to the light guide plate 300, A bandpass filter 500 disposed on the upper side of the light guide plate 300 and a guide panel 180 disposed on the upper side of the light guide plate 300 and supporting the display panel 200, 180), and a display panel (200) on which the upper edge and the side of the display panel It may comprise a top case 190. The

Here, the LED array 410 may be replaced with another type of light source, such as a fluorescent lamp, as the case may be. However, in this case, the region of the absorption wavelength of the band-pass filter film 500 can be shifted and adjusted according to the wavelength spectrum of the light source.

In the meantime, the same reference numerals as in the above-described first embodiment have the same functions, and a description thereof will be omitted.

The light source unit and the display device using the same according to the present invention apply the HOE film selectively absorbing light of a specific wavelength to the upper side of the light guide plate to shape the wavelength characteristic of the emitted light transmitted to the display panel, can do. This improves the color gamut and allows the color gamut to be expanded.

In addition, the light source unit of the present invention can solve the deterioration problem and the environmental pollution problem of the conventional optical sheet by applying the band-pass filter film to the HOE film without material deterioration due to long-time use.

The light leakage problem caused by the omnidirectional reflection characteristic of the conventional optical sheet can also be solved. Particularly, when the omnidirectional reflection occurs, the bezel area is also increased. In the light source unit of the present invention, the absorbed light is totally reflected in the band-pass filter film and is not reflected to the outside, .

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Will be apparent to those of ordinary skill in the art.

100: light guide plate 120: LED array
130: prism sheet 140: bandpass filter film
141: Base material 145: Stack
145a: first insulating layer 145b: second insulating layer
148: protective film 150: diffuser plate
160: Cover Bottom 170: Reflector
180: guide panel 190: case top
200: display panel 300: light guide plate
310: stripe pattern 410: LED array
420: lens unit 500: bandpass filter film

Claims (11)

A light guide plate;
An LED array disposed on one side of the light guide plate; And
And a band-pass filter film disposed on the light guide plate and absorbing at least one of a wavelength between the red light and the green light and a wavelength between the green light and the red light, and totally reflecting the light of the absorbed wavelength. The method according to claim 1,
Wherein the band-pass filter film comprises one or more layers of a pair of insulating layers having a refractive index difference. 3. The method of claim 2,
Wherein the band-pass filter film has a repeated refractive index pattern in the form of a horizontal or inclined shape in at least one of the insulating layers in the pair of insulating layers. The method according to claim 1,
Wherein the band-pass filter film includes a band-pass filter film that absorbs a wavelength of 560 nm to 610 nm. The method according to claim 1,
Wherein the band-pass filter film absorbs a wavelength of a wavelength of 450 nm to 500 nm. The method according to claim 1,
And a lens unit for transmitting light emitted from the LED array to the light guide plate as parallel light, between the light guide plate and the LED array. The method according to claim 6,
Wherein the band-pass filter film is located closest to the light guide plate. 8. The method of claim 7,
And a plurality of stripe patterns perpendicular to the light traveling direction of the light guide plate are formed on the surface of the light guide plate. The method according to claim 1,
A prism sheet disposed between the light guide plate and the band-pass filter film,
And a diffusion plate on the band-pass filter film. A cover bottom having a reflector on the inside thereof;
A light guide plate on a reflection plate in the cover bottom;
An LED array disposed on one side of the light guide plate;
A prism sheet on the light guide plate;
A band pass filter film which is in contact with the prism sheet at its frontmost side and absorbs at least one of a wavelength between red light and green light and a wavelength between green light and red light;
A diffusion plate on the band-pass filter film; And
And a display panel on the diffusion plate. A cover bottom having a reflector on the inside thereof;
A light guide plate on a reflection plate in the cover bottom;
An LED array disposed on one side of the light guide plate;
A lens unit disposed between the light guide plate and the LED array for transmitting light emitted from the LED array to the light guide plate as parallel light;
A band pass filter film which is in contact with the prism sheet at its frontmost side and absorbs at least one of a wavelength between red light and green light and a wavelength between green light and red light; And
And a display panel on top of the band-pass filter.

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