KR101897323B1

KR101897323B1 - Transparent display device

Info

Publication number: KR101897323B1
Application number: KR1020150161388A
Authority: KR
Inventors: 윤종문; 김동용; 정지현
Original assignee: (주)뉴옵틱스
Priority date: 2015-11-17
Filing date: 2015-11-17
Publication date: 2018-09-11
Also published as: KR20170057930A

Abstract

This application relates to a transparent display device.
The transparent display of the present application improves the moire phenomenon that can be induced by the pixel period of the liquid crystal panel and the pattern of the light guide plate while appropriately securing the inherent transparency and can improve the difficulty of applying the backlight unit.

Description

Transparent display device

This application relates to a transparent display device.

Flat panel displays (FPDs) have been replaced with conventional cathode ray tube (CRT) display devices to provide a compact and lightweight display device for portable computers such as notebook computers, PDAs, and mobile phone terminals as well as monitors of desktop computers Lt; RTI ID = 0.0 > system. &Lt; / RTI > Currently available flat panel display devices include a liquid crystal display (LCD), a plasma display panel (PDP), an organic light emitting diode (OLED) The device is favored as a display device used for a mobile device, a computer monitor, and an HDTV due to its advantages such as excellent visibility, easy thinning, low power and low heat generation.

In particular, a liquid crystal display device is a flat panel display device comprising electrode wirings arranged in a lattice shape on a pair of transparent substrates facing each other, a liquid crystal panel having a liquid crystal layer therebetween, and a light source for providing light therebetween, And thus it is advantageous to realize a transparent display.

However, the liquid crystal display device can not emit light by itself, and a separate backlight unit must be provided, which includes one or more optical members for improving light efficiency. Such optical members include a light guide plate, a reflection plate, a diffusion sheet, and a prism sheet.

However, when the optical member is applied to a transparent display, the reflection plate hides an object on the back face, the diffusion sheet lowers the transparency and lowers the visibility of the object on the back face, and the prism sheet distorts the image of the back face, The remaining optical sheets are omitted to constitute a transparent display. However, even if the optical member that affects the transparency is omitted, the light transmissivity of the transparent display is low due to the light control pattern formed on the light guide plate. Therefore, basically, There is a limitation that the visibility is very low, and there is also a problem that moire phenomenon occurs due to interaction with the unit pixel of the liquid crystal panel.

Patent Document 1: Korean Patent Publication No. 2015-0074803

The present application provides a transparent display device which improves the difficulty of applying a backlight unit by improving a moiré phenomenon caused by interaction between a pixel period of a liquid crystal panel and a light guide plate reflection surface pattern.

The present application also provides a transparent display device which can effectively transmit or realize a normal mode without an external light source, while appropriately securing the transparency of the transparent display.

Hereinafter, the transparent display device according to the present application will be described in more detail.

This application relates to a transparent display device.

The transparent display device of the present application includes a pattern shape on the reflective surface of the light guide plate and by shaping the pattern at regular intervals, it is possible to effectively improve the moire phenomenon that can be induced by the application of the backlight unit, It is possible to prevent a decrease in transmittance of the device.

The transparent display device of the present application can also be selectively switched between a transparent mode and a normal mode, and a display image can be implemented regardless of the presence or absence of an external light source by applying a backlight unit.

That is, the present application relates to a liquid crystal panel; And a backlight unit. The backlight unit has a light guide plate arranged so that light from the light source unit and light from the light source unit can enter the liquid crystal panel, and includes a pattern shape formed on the reflection surface. The pattern shape formed on the reflection surface is formed on the first axis at regular intervals.

The light guide plate of the backlight unit according to the present application secures excellent transparency by forming a certain period on the reflection surface, for example, a pattern having a constant period in the first axis direction so as to be suitable for application to a transparent display device And the moiré phenomenon due to the interaction with the pixel period of the liquid crystal panel can be effectively prevented.

The term " transparent display device " in the present application means a display device in which an object positioned on the back surface can be viewed, for example, a display device having a transmittance of 5% or more with respect to light having a wavelength of 550 nm.

The transparent display device includes a liquid crystal panel.

The liquid crystal panel can be applied without limitation in the present application as long as it is a liquid crystal panel applied to a general transparent display device.

In one example, the liquid crystal panel includes a pair of substrates arranged opposite to each other; And a liquid crystal layer disposed between the pair of substrates.

The pair of substrates included in the liquid crystal panel have appropriate transparency and strength, and examples thereof include a transparent plastic substrate and a glass substrate.

The liquid crystal panel may include, in addition to the above-described structure, a well-known structure that can include a liquid crystal panel, for example, an alignment film, a transparent electrode, a color filter substrate, or a black matrix.

The liquid crystal layer in the liquid crystal panel changes its arrangement depending on whether an external action is applied, for example, an external electric field, and selectively transmits or blocks the light emitted from the backlight unit to display an image in units of pixels .

At this time, the moire phenomenon may occur due to the interaction between the unit pixel of the liquid crystal panel and the pattern shape present on the reflection surface in the light guide plate included in the backlight unit described later. However, the transparent display device according to the present application can overcome such moire phenomenon by arranging the pattern shape of the light guide plate with a certain period and regularity, and can provide a transparent display with excellent transparency.

The transparent display device according to the present application includes a backlight unit.

Further, the backlight unit includes a light source portion and a light guide plate.

1 is a schematic diagram of a transparent display device according to the present application. 1, the transparent display device according to the present application includes a liquid crystal panel 1000; And a backlight unit 2000 positioned on the rear surface of the liquid crystal panel 1000 and having a light source unit 100 and a light guide plate 200. Further, a glass substrate 3000 to be described later may be further included on the back surface of the backlight unit 2000.

The backlight unit is disposed on the back surface of the liquid crystal panel, and can provide light to the liquid crystal panel to enable the display device to implement an image.

In one example, the light source unit included in the backlight unit may be arranged so as to allow light to enter the liquid crystal panel.

Generally, a case where a light source is directly disposed on a surface of a liquid crystal panel is referred to as a direct type, and a case where a light source is not directly disposed on a surface of the liquid crystal panel, ), And the backlight unit of the transparent display device according to the present application may be an edge type.

Accordingly, the light source portion may be disposed on at least one side surface of the light guide plate. Further, as a more specific example, the light source unit may be disposed on both sides of the light guide plate, as shown in Fig.

The light source unit may include a light source and a light source substrate designed to dispose the light source.

The light source may include three light emitting diodes (LEDs) that emit red, green, and blue light, respectively, or a single light emitting diode (LED) that emits white light may be used. However, A lamp, an organic light emitting diode (OLED) or a laser diode (LD) can be applied without limitation.

In one example, in a method of emitting light in the light source portion, a method of alternately arranging elements emitting light of red, green, and blue at regular intervals to generate white light therefrom, and then supplying the generated white light to the liquid crystal panel Or a method of supplying white light to the liquid crystal panel by arranging single elements emitting white light at regular intervals may be used.

The backlight unit of the present application may further include other additional configurations, for example, to increase the efficiency with which light from the light source enters the light guide plate.

The backlight unit also includes a light guide plate.

The light guide plate can change the incident light in the form of a point light source into a planar light source. In one example, the light output distribution emitted from the light source has a point light source shape. The light source passing through the light guide plate diffuses through the light guide plate to have a light output distribution in the form of a planar light source on the upper surface of the light guide plate facing the liquid crystal panel Can be released.

2, the light guide plate 200 of the present application includes a light-incident portion 201 and a light-emitting portion 202 for guiding light to the liquid crystal panel, (203, P).

The light-incident portion of the light guide plate may be formed on at least one of four surfaces perpendicular to the surface of the light-emitting portion of the light guide plate, which will be described later.

In one example, the light-incident portions of the light guide plate may be formed on both sides of the light guide plate as shown in Fig.

In addition, the light incident surface of the light guide plate and the light emitted from the light source may be perpendicular to each other. That is, the light incident surface 204 of the light guide plate and the axis 101 of light emitted from the light source 100 may be vertical as shown in FIG.

In another example, the surface of the light-incoming portion of the light guide plate may have a concave shape, a predetermined radius of curvature with respect to the light source, and a structure that surrounds the light source.

The light emitting portion of the light guide plate may be formed on the upper surface parallel to the light reflection portion of the light guide plate, for example, perpendicular to the light entrance portion of the light guide plate. The light emitter can emit the light incident through the light emitter to a liquid crystal panel and the direction of the light emanating from the light emitter is substantially perpendicular to the emitter's surface and the intensity of the light is uniformly distributed can do.

The light guide plate includes a pattern shape formed on the reflection surface. The pattern shape is formed at regular intervals in the first axis direction.

The light guide plate of the backlight unit according to the present application includes a pattern shape of a predetermined period on the reflection surface so as to be suitable for application to a transparent display device, thereby ensuring excellent transparency and, at the same time, The moire phenomenon can be effectively prevented.

The pattern formed on the reflective surface of the light guide plate functions to reflect the light traveling from the light incident portion to the light emitting portion, and typically has a low pattern density around the light entering portion, The density of the recorded pattern is set to be high, and the desired reflection characteristic of the light guide plate is appropriately secured. However, in this case, there is a problem that moire phenomenon occurs due to the interaction between the unit pixel of the liquid crystal panel and the arrangement of the reflective surface pattern of the light guide plate.

Thus, by forming the pattern shape formed on the reflective surface with a certain period in the first axis direction, the light guide plate according to the present application can improve the moire phenomenon while ensuring the desired reflection characteristic.

In the light guide plate of the present application, the interval of the pattern shapes formed in the first axis direction is designed to have a predetermined magnification with the unit pixel period of the liquid crystal panel, whereby the moire phenomenon can be improved while ensuring the desired reflection characteristic .

In one example, the periodicity of the pattern shape formed in the first axis direction may be 0.1 to 2 times the pixel pitch of the liquid crystal panel. In another example, the periodicity of the pattern shape may be in the range of 0.15 to 1.8 or 0.2 to 1.6 of the pixel pitch in the liquid crystal panel. In the above, the pixel pitch of the liquid crystal panel may be the width or the length of the unit pixel of the liquid crystal panel.

The direction of the first axis may be, for example, inclined at an angle with respect to an axis of light emitted from the light source unit or an axis perpendicular to the axis of the light.

In one example, the direction of the first axis may be one to twenty degrees from the direction of the axis incident on the light guide plate.

Specifically, as shown in Fig. 3, the direction A of the first axis on which the pattern shape is formed is set to a predetermined angle (?) With respect to the direction X of the axis incident on the light guide plate, for example, 1 Lt; / RTI > to 20 degrees.

In another example, the direction of the first axis may be inclined by 1 to 20 degrees with respect to the direction perpendicular to the direction of the axis incident on the light guide plate from the light source portion.

4, the direction A of the first axis on which the pattern shape is formed is set to a predetermined angle? (T) with respect to the vertical direction Y of the direction X of the axis incident on the light guide plate, ), For example, from 1 degree to 20 degrees.

In this way, when a pattern is formed on the first axis inclined at 1 degree to 20 degrees with respect to the direction of the axis incident to the light guide plate or the direction orthogonal to the axis, the moire phenomenon can be improved.

The direction of the first axis on the reflective surface of the light guide plate may be inclined by 2 to 15 degrees or 5 to 10 degrees with respect to the direction of the axis incident on the light guide plate or the direction orthogonal to the axial direction in another example.

The light guide plate of the present application may further include a pattern shape formed at regular intervals on a second axis having a direction different from the first axis.

The term "first axis and second axis" in the present application means two axes which are different in the direction in which the pattern shape formed on the reflection surface of the light guide plate is arranged, and the number of each axis does not determine the direction of the pattern shape .

The fact that the pattern shape is formed with a certain period in the first axis and the second axis direction can mean that the pattern shape has a lattice arrangement, for example.

For example, as shown in FIG. 5, the reflective surface pattern of the light guide plate has a pattern with a predetermined pitch X _{p in} the first axis direction A, and the pattern shape has a predetermined angle a has a direction (B) at a constant pitch (Y _p) forming, first there is a pattern formed in a first axial direction (a '), and ultimately to the first axis and the first axis and the second axis has a different direction Patterns may be formed with a certain period.

The directions of the first axis and the second axis may be, for example, 5 to 90 degrees. In another example, the directions of the first and second axes may be in the range of 10 degrees to 90 degrees, 20 degrees to 90 degrees, 30 degrees to 90 degrees, 40 degrees to 90 degrees, or 50 degrees to 90 degrees, The directions of the first axis and the second axis may be orthogonal to each other. In the above, orthogonal means a substantially vertical direction, and can be understood to include an error of about 2 degrees.

As described above, the pattern shape may be formed with a certain period in the first axis direction and the second axis direction, and the predetermined period may be different according to the direction of each axis.

In one example, the pattern shape may be formed with a first pitch in the first axis direction and a second pitch different from the first pitch in the second axis direction.

In a more specific example, when the first axis direction is inclined by 1 degree to 20 degrees with respect to the direction (Y) orthogonal to the direction of the axis incident on the light guide plate, the pattern shape formed in the first axis direction, A pitch of 0.7 to 1.5 times the pixel pitch, and a pattern shape formed in the second axis direction may have a pitch of 0.1 to 0.5 times the pixel pitch of the liquid crystal panel, but the present invention is not limited thereto.

The size of the pattern shape formed on the reflective surface of the light guide plate may be, for example, in the range of 10 to 300 占 퐉, 20 to 250 占 퐉, or 30 to 200 占 퐉, but not limited thereto, And the numerical value may be varied to effectively improve the moire phenomenon.

The shape of the pattern formed on the reflective surface of the light guide plate may include, for example, a center portion and a peripheral portion surrounding the central portion, and the circumference of the peripheral portion may include irregular protrusions. Such a pattern shape may be formed by a silk screening technique, a printing technique, a laser etching technique, a deposition technique, a pressing technique, or a roll stamping technique. However, in the case of using a roll stamping technique, It is preferable because it can be more effective for the improvement.

The light guide plate may be made of PMMA (Poly Methyl Methacrylate), polycarbonate or glass based material having excellent light transmittance.

In one embodiment of the production of the light guide plate, the pattern may be manufactured by forming the pattern at regular intervals using a roll stamping process on one side of the rectangular PMMA transparent panel, but the present invention is not limited thereto.

The backlight unit according to the present application may further include a light path change layer disposed on one or both surfaces of the light guide plate.

The term " light path changing layer " in the present application means a layer in which the path of incident light can be changed according to whether an external electric field is applied or not, and a layer in which light shielding, scattering, or reflection is selectively controlled.

The light-path change layer may include, for example, a light-path change material. The light path changing material means a material capable of selectively controlling shielding, scattering, or reflection of a target light of the light path changing layer by changing the alignment direction according to whether an external electric field is applied. The light-path changing material may be, for example, a liquid crystal compound.

The kind of the light path changing layer may be adopted and used without limitation in the present application as long as it includes the above-mentioned light path changing substance, for example, a liquid crystal compound.

In one example, the light-path change layer may be a polymer dispersed liquid crystal layer or a cholesteric liquid crystal layer.

The polymer dispersed liquid crystal layer may include, for example, a polymer network and a liquid crystal compound dispersed in the polymer network.

In one example, the polymer network may be an oriented network of precursors comprising an orienting compound.

As used herein, the term " oriented network of precursors comprising an orienting compound " can refer to a polymer network comprising, for example, a precursor comprising an orienting compound, or a polymer network comprising said precursor crosslinked or polymerized.

The term " orienting compound " in the present application means a compound that is orientationally ordered through, for example, irradiation of light or the like, and is capable of interacting with adjacent liquid crystals through an interaction such as anisotropic interaction in the aligned state May refer to a compound capable of orienting the compound in a predetermined direction. The compound may be a monomolecular compound, a monomeric compound, an oligomeric compound or a polymeric compound.

As the orienting compound, for example, a photo aligning compound may be used. The photo-aligning compound may mean a compound capable of aligning in a predetermined direction by irradiation of light, for example, irradiation of linearly polarized light, to induce orientation of the adjacent liquid crystal compound.

The ratio within the polymer dispersed liquid crystal layer of the polymer network can be suitably selected within a range that does not impair the desired physical properties. For example, the polymer dispersed liquid crystal layer may be contained in a ratio of about 20 to 50 parts by weight of the polymer network and about 50 to 80 parts by weight of the liquid crystal compound, but the ratio may be appropriately changed according to need.

The liquid crystal compound contained in the polymer dispersed liquid crystal layer is a liquid crystal molecule which can be changed in alignment direction by the above-described polymer network. For example, a nematic liquid crystal compound is exemplified, but is not limited thereto.

The driving principle of the transparent mode and the normal mode of the polymer dispersed liquid crystal layer will be described in more detail.

Specifically, in the state where no external voltage is applied, the liquid crystal compound dispersed on the polymer network exists in a state in which alignment is not possible without orientation, so that light is scattered inside the polymer dispersed liquid crystal layer, And when an external voltage is applied, the liquid crystal compound dispersed on the polymer network is aligned in one direction by the dielectric constant characteristics or the like, so that light passes through the polymer dispersed liquid crystal layer as it is, A transparent mode can be realized.

When the light path change layer is a cholesteric liquid crystal layer, the light path change layer may include a cholesteric liquid crystal compound. The alignment direction of the cholesteric liquid crystal compound changes depending on whether an external electric field is applied, for example, to selectively implement a normal mode and a transparent mode.

That is, the cholesteric liquid crystal compound in the cholesteric liquid crystal layer has a helical structure in which the director of the liquid crystal molecule is twisted along a helical axis, and in a state in which no external electric field is applied, Scattered to realize a normal mode of the display device and transmit light in a state where an external electric field is applied, thereby realizing a transparent mode of the display device.

The method for forming such a light path changing layer is not particularly limited. For example, a method of coating a composition containing the above-mentioned substance on an arbitrary substrate and curing the composition may be used, but the present invention is not limited thereto .

The optical path change layer, such as the polymer dispersed liquid crystal layer or the cholesteric liquid crystal layer, can switch between a transparent mode or a normal mode depending on whether an external action is applied, thereby improving the brightness of an image, To increase the visibility of the object located in the area.

In one example, the light path change layer may selectively implement a transparent mode and a normal mode.

The term " transparent mode " in the present application may refer to a mode in which an external electric field is applied to the light path change layer so that an object positioned on the back of the transparent display can be viewed, for example, a transmittance %) Is 78% or more.

The term " normal mode " in the present application may refer to a state in which an external electric field is not applied to the light path change layer and an object located on the back surface of the transparent display is not visible. For example, (%) Is 10% or less.

The light path changing layer may be formed on one or both surfaces of the light guide plate, for example.

6 is a schematic diagram of a transparent display device further comprising a light path change layer according to the present application.

6, when the backlight unit 2000 according to the present application further includes the light path change layer 300, the light path change layer 300 is formed on the liquid crystal panel (not shown) of the light guide plate 200 1000 may be located on the opposite side of the plane on which they are located.

The backlight unit may further include an electrode layer disposed opposite to both surfaces of the light path change layer so as to apply an electric field to the light path change layer.

In the transparent display device according to the present application, the backlight unit may be disposed on the back surface of the liquid crystal panel so that the transmissive mode or the normal mode can be implemented effectively even in the absence of an external light source.

In one example, the backlight unit implements an off-mode with an external light source and an on-mode with no external light source.

The off-mode may mean a mode in which a light source included in the backlight unit is turned off and a transparent display is implemented using a natural light source.

The on-mode may mean a mode in which a light source included in the backlight unit is turned on to implement a transparent display. When the backlight unit further includes a light path change layer, in the on-mode or off-mode, an electric field is applied to the light path change layer separately to realize a transparent mode, or an electric field is not applied, Mode. &Lt; / RTI >

The transparent display according to the present application may further comprise control means for implementing the on-mode or off-mode of the backlight unit.

The transparent display device according to the present application may further include, for example, a glass substrate. The glass substrate is for maintaining the durability and rigidity of the transparent display device, and may be located on the opposite side of the surface on which the liquid crystal panel of the backlight unit is located, for example.

More specifically, the glass substrate may be present on the opposite side of the backlight unit 2000 where the liquid crystal panel 1000 is located, as shown in Fig.

The transparent display device according to the present application can attain a high transmittance and light efficiency even though the backlight unit is introduced due to the pattern shape formed at regular intervals on the light guide plate reflection surface.

In one example, the transparent display device may have a transmittance of 5% or more for light with a wavelength of 550 nm. In another example, the transmittance of the transparent display device may be at least 5.5%, at least 6%, or at least 7%. The upper limit of the transmittance is not particularly limited, and may be, for example, 80% or less and 70% or less.

The present application can provide a transparent display device which improves the moire phenomenon caused by interaction between the pixel period of the liquid crystal panel and the light guide plate reflection surface pattern, thereby improving the difficulty of applying the backlight unit.

The present application can also provide a transparent display device that can effectively transmit or realize a normal mode without an external light source, while appropriately securing transparency of the transparent display.

1 and 6 are schematic diagrams of a transparent display device according to the present application.
2 is a schematic diagram of a backlight unit according to the present application.
Figs. 3 to 5 are schematic diagrams for explaining a reflection surface pattern shape of the light guide plate according to the present application. Fig.

Hereinafter, the transparent display device according to the present application will be described in more detail with reference to examples and comparative examples. However, the following examples are merely examples according to the present application, and the technical idea of the present application is not limited. It will be apparent to those of ordinary skill in the art.

[ Example 1] - Manufacture of transparent displays

Manufacture of light guide plate

A pattern shape having a size of about 55 mu m was formed on one surface of the PMMA transparent panel at 100 to 110 DEG C using a roll stamping method.

Specifically, the pattern shape is formed at a pitch (X pitch) corresponding to 1.5 times the panel pixel in the first axis direction which is inclined by about 10 degrees with respect to the direction in the direction of the axis incident on the light guide plate, (Y pitch) corresponding to 0.20 times of the panel pixel in the second axis direction which is about 90 degrees from the first axis direction.

Manufacture of transparent displays

Light sources were disposed on both sides of the light guide plate to manufacture a backlight unit. Thereafter, one side of the backlight unit was bonded to the LCD panel, and a glass substrate was included on the backlight unit side where the LCD panel was not formed to manufacture a transparent display.

[ Example 2] - Manufacture of transparent displays

(X pitch) corresponding to 0.75 times of the panel pixel in the first axis direction which is inclined by about 10 degrees with respect to the direction perpendicular to the direction of the axis incident on the light guide plate, And a pitch (Y pitch) corresponding to 0.20 times of the panel pixels in the second axis direction, which is about 90 degrees from the first axis direction, is manufactured in the same manner as in Embodiment 1, Respectively. Also, a transparent display was produced in the same manner as in Example 1 using the light guide plate.

[ Comparative Example One]

The pattern shape is formed at a pitch (X pitch) corresponding to 1.5 times of the panel pixel in the first axial direction which is inclined by about 0.5 degrees with respect to the direction of the axis incident on the light guide plate, The light guide plate and the transparent display device were manufactured in the same manner as in Example 1 except that the light guide plate and the transparent display device were formed at a pitch (Y pitch) corresponding to 0.20 times of the panel pixel in the direction orthogonal to the panel pixel.

[ Comparative Example 2]

The pattern shape is formed at a pitch (X pitch) corresponding to 1.5 times the panel pixel in the first axial direction which is inclined by about 21 degrees with respect to the direction perpendicular to the direction of the axis incident on the light guide plate, The light guide plate and the transparent display device were manufactured in the same manner as in Example 1, except that the pitch was set at a pitch (Y pitch) corresponding to 0.20 times of the panel pixel in the direction perpendicular to the first axis direction.

[ Experimental Example One] - Moire Observation of phenomenon

The presence or absence of the moire phenomenon of the transparent display device manufactured according to the examples and the comparative example was observed using a naked eye and the degree of occurrence of the moire phenomenon was evaluated as A (little occurrence of moiré), B ), C (severe occurrence of moire), or D (very serious occurrence of moire), which are shown in Table 1 below.

As shown in the following Table 1, the transparent display device according to the present application is characterized in that the light from the light source is reflected by the light guide plate in the axial direction inclined by 1 to 20 degrees with respect to the direction of the axis incident to the light guide plate, The occurrence of moire phenomenon can be minimized by forming a pattern shape having a constant period.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Moiré phenomenon result photograph

Visual observation result B A D D

100: Light source
101: axis of light emitted from the light source
200: light guide plate
201: light-
202:
203:
203, P: pattern shape
204:
300: light path changing layer
1000: liquid crystal panel
2000: Backlight unit
3000: glass substrate
A, A ': First axis
B: Second axis
X: Direction of axis incident on light guide plate
Y: Light perpendicular to the direction of the axis incident on the light guide plate

Claims

In a transparent display device including a liquid crystal panel and a backlight unit,
Wherein the backlight unit includes a light source unit and a light guide plate disposed so that light from the light source unit can enter the liquid crystal panel,
Wherein the light guide plate includes a reflective surface having a pattern shape formed at regular intervals on a first axis and a second axis having a direction different from the first axis,
The direction of the first axis is a direction inclined by 1 to 20 degrees with respect to a direction of an axis incident on the light guide plate,
The second axis is at an angle of 5 to 90 degrees with the first axis,
The pattern shape formed in the first axis direction has a pitch of 0.7 to 1.5 times the pixel pitch of the liquid crystal panel,
The pattern shape formed in the second axis direction has a pitch of 0.1 to 0.5 times the pixel pitch of the liquid crystal panel,
Wherein the shape of the pattern includes a central portion and a peripheral portion surrounding the central portion, wherein a circumference of the peripheral portion is in the form of an irregular projection.

The method according to claim 1,
A liquid crystal display device comprising: a pair of substrates arranged to face each other; And
And a liquid crystal layer positioned between the pair of substrates.

The method according to claim 1,
And the light source portion is disposed on at least one side surface of the light guide plate.

delete

The method according to claim 1,
And the pattern shape has a size of 10 mu m to 300 mu m.

The method according to claim 1,
Wherein the backlight unit further comprises a light path changing layer disposed on one or both sides of the light guide plate.

12. The method of claim 11,
Wherein the light path changing layer selectively implements a transparent mode and a normal mode depending on whether an electric field is applied or not.

12. The method of claim 11,
Wherein the optical path changing layer is a polymer dispersed liquid crystal layer or a cholesteric liquid crystal layer.

The method according to claim 1,
The backlight unit implements an off-mode with an external light source, and implements an on-mode with no external light source.

The method according to claim 1,
Wherein the backlight unit is located on the opposite side of the surface on which the liquid crystal panel is located.

The method according to claim 1,
Transparency is at least 5%.