KR20170050701A

KR20170050701A - Polarizer for improving brightness and liquid crystal display device having thereof

Info

Publication number: KR20170050701A
Application number: KR1020150152568A
Authority: KR
Inventors: 한상대; 어윤정; 이건우
Original assignee: 엘지디스플레이 주식회사
Priority date: 2015-10-30
Filing date: 2015-10-30
Publication date: 2017-05-11

Abstract

In the present invention, a light path control layer is provided on a lower polarization plate in a region corresponding to a hot spot of a light guide plate to prevent unevenness of brightness in the region by changing the path of light which is incident to the region, wherein to this end, the light path control layer is composed of a base film, a phase separating means disposed on the base film and separating the phase of the inputted light, and a diffusion layer disposed on the base film.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate for improving luminance and a liquid crystal display device having the polarizing plate.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate, and more particularly, to a polarizing plate capable of realizing a uniform luminance and a liquid crystal display device having the polarizing plate.

2. Description of the Related Art [0002] With the development of information electronic devices for realizing high-resolution and high-quality images of portable devices such as mobile phones and notebook computers and HDTVs, flat panel display devices ) Are increasingly in demand. As such flat panel display devices, a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), and an organic light emitting diode (OLED) have been actively studied. However, Liquid crystal display devices (LCDs) are in the spotlight at present due to the realization of large-area screens.

Such a liquid crystal display element is a transmissive display element and displays a desired image gradation on the screen by adjusting the amount of light transmitted through the liquid crystal layer by the refractive index anisotropy of liquid crystal molecules. Therefore, in the liquid crystal display device, a back light for providing light that transmits the liquid crystal layer for displaying an image is provided. Generally, the backlight unit can be divided into two types according to the structure of the light source.

One type is a direct type, and a lamp or a light emitting device (LED) as a light source is disposed on the back surface of the liquid crystal panel to directly supply light from the bottom to the panel direction. A lamp or an LED is disposed on a side surface of the liquid crystal panel, and light is supplied to the liquid crystal panel through light path conversion means such as a light guide plate.

The direct type liquid crystal display device is mainly applied to manufacture a large area liquid crystal display device such as a large-screen TV because the light emitted from a light source is directly supplied to a liquid crystal panel and thus can be applied to a large-

On the other hand, since the side type light source is provided on the side of the liquid crystal panel and supplies light to the liquid crystal panel through the light guide plate, it is difficult to apply to a large area liquid crystal panel as compared with the direct type, It becomes difficult. However, in the case of the side-by-side method, since the backlight portion is located on the side surface, the thickness of the liquid crystal display device can be reduced. Therefore, such a side-by-side method is mainly applied to the backlight unit of a liquid crystal display device provided in a mobile apparatus or the like requiring a thin-thickness display apparatus.

Conventionally, a fluorescent lamp such as CCFL (Cold Cathode Fluorescent Lamp) or EEFL (External Electrode Fluorescent Lamp) is mainly used as a light source of such a backlight unit. Recently, however, a light emitting device Device) is widely used. Since such a light emitting device emits RGB monochromatic light, it has a merit that when it is applied to a backlight, the color reproduction rate is good and driving power can be reduced.

1 is an exploded perspective view showing a structure of a conventional side-type backlight unit including an LED.

1, the conventional side-type backlight unit includes an LED 34 positioned at one end of a liquid crystal panel and supplying light to the liquid crystal panel, an LED substrate 32 on which the LED 34 is mounted, A light guide plate 50 disposed on the light guide plate 50 and arranged to face the LED 34 to guide the light emitted from the LED 34 and to supply light to the upper portion of the light guide plate 50, An optical sheet 38 composed of a diffusion sheet 38a and prism sheets 38b and 38c for improving the efficiency of light emitted from the light guide plate 50 and a light guide plate 50 disposed below the light guide plate 50, And a reflection plate 36 for reflecting the light onto the display panel 50.

In the backlight unit of this structure, the light emitted from the LED 34 is incident into the light guide plate 50 through the light entrance surface of the light guide plate 50. In the light guide plate 50, after the incident light is totally reflected, And then supplied to the liquid crystal panel as a light source. At this time, a reflection plate 36 is provided under the light guide plate 50 to improve the light efficiency by introducing light output through the lower surface of the light guide plate 50 into the light guide plate 50 again. A diffusion sheet 38a and prism sheets 38b and 38c are disposed on the upper surface of the light guide plate 50 to improve the efficiency of light output through the upper surface of the light guide plate 50. [

However, the following problems arise in the conventional backlight unit having the above structure.

Unlike the fluorescent lamp, the LED 34, which is mainly used in recent years, is a point light source. As shown in FIG. 2, the LED 34 is located at a certain distance g1 from the light entrance surface of the light guide plate 50, G2.

The light emitted from the LED 34 is irradiated to a certain region of the light incidence plane of the light guide plate 50 and is input into the light guide plate 50. Since the LED 34 is a point light source, Therefore, a light irradiation area and a light irradiation area are generated on the light entrance surface of the light guide plate 50.

On the other hand, the light is refracted at the light incident surface of the light guide plate 50, is incident inside, is totally propagated through the light guide plate 50 to the opposite surface, and then supplied to the liquid crystal panel through the upper surface. The light emitted from the specific LED 34 and incident into the light guide plate 50 spreads throughout the light guide plate 50 through total internal reflection and is mixed with the light emitted from the other LED 50, And light of uniform luminance is supplied to the liquid crystal panel.

However, the light incident into the light guide plate 50 is refracted at the light incidence surface and travels to a region spaced a certain distance from the light incidence plane. In the light incidence plane of the light guide plate 50, The light does not reach or a region having a small luminance is generated in a portion of the upper surface adjacent to the light-incident surface. That is, hot spots or dead areas are generated due to uneven brightness on the upper surface adjacent to the light incidence surface. These hot spots and quadrature regions cause hot spots or dust regions in corresponding areas on the screen when light is supplied to the liquid crystal panel, thereby deteriorating the image quality of the liquid crystal display device.

Such a hot spot or dead area can be eliminated by reducing the gap g2 between the LED 34 and the LED 34, but in this case, the number of the LEDs 34 increases and manufacturing costs increase.

It is also possible to increase the distance g1 between the LED 34 and the light incident surface of the light guide plate 50 to increase the area of the light irradiation area irradiated from the one LED 34 to the light incident surface, The hot spot or the warp region can be removed by overlapping with the light irradiation region that emits light from the light source 34. However, in this case, the bezel of the liquid crystal display element becomes large, so that the narrow bezel required in recent years can not be satisfied.

On the other hand, the diffusion sheet 38a and the prism sheets 38b and 38c are provided on the upper surface of the light guide plate 50 so that the light supplied to the liquid crystal panel has a uniform luminance. The diffusion sheet 38a and the prism sheet 38b and 38c are designed so as to have a uniform luminance as a whole by diffusing and straightening the light output from the entire upper surface of the light guide plate 50. The light emitted from the hot spot area on the upper surface adjacent to the light entrance surface of the light guide plate 50 There was a limit to making the luminance uniform. Of course, the diffusion sheet 38a and the prism sheets 38b and 38c may be provided in a specially designed manner to uniform the brightness of the light output from the hot spot area on the upper surface adjacent to the light entrance surface of the light guide plate 50. However, It is inefficient to newly fabricate the entire diffusion sheet 38a and the prism sheets 38b and 38c for the luminance uniformity of the area.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a polarizing plate having an optical path control layer in a part of a polarizing plate and capable of changing the path of light emitted from a hot spot region of the light guide plate to supply uniform light to the liquid crystal panel And to provide a liquid crystal display element.

In order to achieve the above object, in the present invention, a light path control layer is provided on a lower polarizer plate in a region corresponding to a hot spot of a light guide plate, thereby changing the path of light incident on this region, thereby preventing luminance unevenness in this region.

The light path control layer is composed of a base film, phase separating means disposed on the base film for phase-separating light inputted thereto, and a diffusion layer disposed on the base film. The phase separating means is composed of a prism, a lenticular lens, and a fine lens, and the prism and the lenticular lens extend along the arrangement direction of the LED, which is a point light source. Further, the fine lenses are arranged in a regular or irregular manner.

The light path control layer is disposed in a region corresponding to the hot spot region of the light guide plate to change the path of light input from the hot spot region to make the brightness of light in this region uniform.

The liquid crystal display device according to the present invention includes a liquid crystal panel, a light guide plate disposed below the liquid crystal panel, and a light guide plate for emitting light to the liquid crystal panel through the light guide plate, A first polarizing plate disposed on the lower surface of the liquid crystal panel to polarize light input to the liquid crystal panel and changing a path of light incident on the partial area, and a second polarizer disposed on the upper surface of the liquid crystal panel, And a second polarizer plate for controlling transmittance.

In the present invention, the following effect can be obtained by providing the optical path control layer in the polarizing plate.

First, by arranging the light path control layer in the region corresponding to the hot spot region of the light guide plate, the brightness of the light input from the hot spot region of the light guide plate is uniformized and supplied to the liquid crystal panel, thereby deteriorating the image quality in which bright lines and dark lines are generated in the liquid crystal display elements .

Second, in the present invention, since the light of uniform luminance can be provided to the liquid crystal panel without increasing the number of LEDs used, it is possible to prevent an increase in cost due to an increase in the number of LEDs.

Third, in the present invention, it is possible to provide a uniform brightness of light to the liquid crystal panel without increasing the interval between the LED and the light-incident surface of the light guide plate, thereby reducing the area of the bezel where the LEDs are disposed, .

1 is an exploded perspective view showing a structure of a conventional backlight unit;
2 is a diagram showing a hot spot occurring in a conventional backlight unit;
3 is an exploded perspective view showing a structure of a liquid crystal display element according to a first embodiment of the present invention.
4A to 4C are diagrams showing the structure of a polarizing plate according to the first embodiment of the present invention.
5A and 5B are diagrams showing the structure of an optical path control layer of a polarizing plate according to a first embodiment of the present invention.
6 is a view showing a path of light in an optical path control layer according to the present invention;
7 is a view showing another structure of an optical path control layer of a polarizing plate according to the first embodiment of the present invention.
8A and 8B are diagrams showing the structure of an optical path control layer of a polarizing plate according to a second embodiment of the present invention.
9 is a view showing a structure of an optical path control layer of a polarizing plate according to a third embodiment of the present invention.
10 is a view showing a structure of an optical path control layer of a polarizing plate according to a fourth embodiment of the present invention.
11A and 11B are views showing the structure of an optical path control layer of a polarizing plate according to a fifth embodiment of the present invention.

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

3 is an exploded perspective view illustrating a liquid crystal display device according to a first embodiment of the present invention. As shown in FIG. 3, the liquid crystal display according to the present invention includes a liquid crystal panel 110 and a backlight unit. The liquid crystal panel 110 includes a first substrate 101 and a second substrate 103 and a liquid crystal layer (not shown) between the first substrate 101 and the second substrate 103. The liquid crystal panel 110 adjusts the transmittance of light transmitted through the liquid crystal layer And implements the image.

The backlight is for supplying light to the liquid crystal panel 110. A plurality of LEDs (Light Emitting Devices) 134 are disposed on the lower side of the liquid crystal panel 110 and emit light as a signal is applied thereto. A light guide plate 150 disposed at a lower portion of the liquid crystal panel 110 and guiding light emitted from the LED 134 to the liquid crystal panel 110; Diffusion sheet 138a and prism sheets 138b and 138c which are provided between the light guide plate 150 and the light guide plate 150 to diffuse and concentrate the light guided from the light guide plate 150 and supplied to the liquid crystal panel 110, And a reflection plate 136 disposed below the light guide plate 150 and reflecting the light guided to the lower portion of the light guide plate 150 back to the light guide plate 150.

After the LED substrate 132, the reflection plate 136, the light guide plate 150 and the optical sheet 138 of the backlight unit are housed in the lower cover 140, the lower cover 140 and the guide panel 162 are coupled Assembled.

A liquid crystal panel 110 is placed on the guide panel 162. The guide panel 162 is formed in a rectangular shape and an edge area of the liquid crystal panel 110 is placed on the guide panel 162.

The liquid crystal panel 110 includes a first substrate 101 and a second substrate 102 and a liquid crystal layer (not shown) disposed between the first substrate 101 and the second substrate 102 do. Though not shown in the figure, a plurality of gate lines and data lines are vertically and horizontally arranged on the first substrate 101 to define a plurality of pixel regions, and a thin film transistor serving as a switching element is formed in each pixel region A pixel electrode formed on the pixel region is formed. The thin film transistor includes a gate electrode connected to a gate line, a semiconductor layer formed by stacking amorphous silicon or the like on the gate electrode, and a source electrode and a drain electrode formed on the semiconductor layer and connected to the data line and the pixel electrode .

The second substrate 102 includes a color filter composed of a plurality of sub-color filters embodying colors of red (R), green (G) and blue (B) And a black matrix for blocking light passing through the liquid crystal layer.

The first substrate 101 and the second substrate 102 constituted as described above are adhered to each other by a sealant (not shown) formed on the periphery of the image display region to constitute a liquid crystal panel, and the first substrate 101 (Not shown) formed on the first substrate 101 or the second substrate 102. As shown in FIG.

The first polarizing plate 170 and the second polarizing plate 180 are attached to the first substrate 101 and the second substrate 102 and are input to and output from the liquid crystal panel 110 The light is polarized to realize an image.

The first substrate 101 is formed to have a smaller area than the second substrate 102. When the first substrate 101 and the second substrate 102 are attached together, A pad region which is not covered by the second substrate 102 and which is exposed to the outside is formed, and a gate pad and a data pad, which are electrically connected to the gate line and the data line, are formed in the pad region, Is supplied to the gate line and the data line of the first substrate 101 through the gate pad and the data pad.

Although not shown in the drawing, one end of an FPC (flexible printed circuit) having a gate driving element and / or a data driving element mounted thereon is connected to the pad region to supply a scanning signal and an image signal .

The light guide plate 150 is for guiding the light emitted from the LED 134 to the liquid crystal panel 110. The light guide plate 150 is disposed on one side of the light guide plate 150, And is then output to the outside of the light guide plate 150. At this time, the light guide plate 150 is a rectangular parallelepiped. The light guide plate 150 is formed of a material such as PMMA (Polymethyl-Methacrylate), glass or polyethylene terephthalate (PET), and an engraved pattern or a relief pattern is formed on the lower surface thereof.

The light incident into the light guide plate 150 through the light incident surface of the light guide plate 150 is reflected by the upper surface and the lower surface of the light guide plate 150 and propagates to a side opposite to the light entrance surface. The light incident on the upper surface of the light guide plate 150 at a critical angle or more with respect to the normal to the upper surface of the light guide plate 150 is totally reflected and propagated from the upper surface of the light guide plate 150 to the inside of the light guide plate 150, And is supplied to the liquid crystal panel 110.

The optical sheet 138 is supplied to the liquid crystal panel 110 by improving the efficiency of light output from the light guide plate 150. The optical sheet 138 includes a diffusion sheet 138a for diffusing the light output from the light guide plate 150 and a first diffusion sheet 138a for condensing the light diffused by the diffusion sheet to supply uniform light to the liquid crystal panel 110. [ A prism sheet 138b and a second prism sheet 138c. At this time, the diffusion sheet 138a is provided with one sheet, but the prism sheet includes a first prism sheet 138b and a second prism sheet 138c in which the prism crosses vertically in the x-, y- The light is refracted in the axial direction to improve the linearity of the light.

As the LED 134, R, G, B LEDs emitting white light of R (Red), G (Green) and B (Blue), or LED devices emitting white light may be used.

When monochromatic LEDs emitting monochromatic light are arranged, monochromatic LEDs of R, G, and B are alternately arranged at regular intervals to mix monochromatic light emitted from the LEDs into white light and then to the liquid crystal panel 110, A plurality of LED elements are arranged at regular intervals to supply white light to the liquid crystal panel 110. [

The white light LED device comprises a blue LED that emits blue light and a phosphor that emits yellow light by absorbing blue monochromatic light. The blue monochromatic light output from the blue LED and the yellow monochromatic light emitted from the phosphor are mixed to form a liquid crystal And is supplied to the panel 110. Although the LEDs 134 are disposed on one side of the light guide plate 150, the LEDs 134 may be disposed on both sides of the light guide plate 150.

The LED 134 is mounted on an LED substrate 132 made of a metal or a flexible film. The LED substrate 132 is disposed along a side surface of the light guide plate 150 and faces a side surface of the light guide plate 150. An LED 134 is mounted on the LED substrate 132, The light from the LED 134 is incident on the light guide plate 150. [

A flexible circuit board 133a is attached to an end of the LED substrate 132 and a wire 133b is attached to an end of the flexible circuit board 133a. The flexible circuit board 133a and the wire 133b are connected to a driving circuit portion outside the liquid crystal display device so that the LED 134 mounted on the LED substrate 132 is connected to the driving circuit portion of the liquid crystal display device, The LED controller drives the LED 134 according to the input signal. A signal wiring is formed on the upper surface and / or the lower surface of the flexible circuit board 133a and the signal wiring is electrically connected to the wire 133b so that the signal of the driving circuit portion is transmitted to the wire 133b and the signal of the flexible circuit board 133a And is input to the LED substrate 132 through the wiring.

Meanwhile, the present invention is not limited to the LED 134 as a point light source for supplying light to the liquid crystal panel 110. In the present invention, the LED 134 is illustrated as an example of a light source for convenience of explanation. The light source of the present invention is not limited to the LED 134.

The guide panel 162 is coupled to the lower cover 140 in such a manner that the upper surface thereof surrounds the edge of the optical sheet 138 of the liquid crystal panel 110 and the side surface of the lower cover 140. The liquid crystal panel 110 is seated on the upper surface of the guide panel 162.

A reflection plate 136 is disposed on the lower portion of the light guide plate 150 and the upper portion of the lower cover 140. The reflection plate 136 reflects the light emitted from the lower surface of the light guide plate 150 and reflects the light to the inside of the light guide plate 136, thereby improving the light efficiency.

The first polarizing plate 170 and the second polarizing plate 180 are attached to the lower surface and the upper surface of the liquid crystal panel 110. The first polarizing plate 170 linearly polarizes the light incident from the backlight, And the second polarizing plate 180 is set to be parallel or perpendicular to the optical axis of the first polarized light 170 so that the optical axis of the second polarizing plate 180 is perpendicular to the optical axis of the liquid crystal layer 110 of the liquid crystal panel 110, Polarizing plate 180. The light transmittance of the light passing through the liquid crystal panel 110 is controlled by transmitting only the light parallel to the polarization direction of the polarizing plate 180.

Meanwhile, in the present invention, a path of light emitted from the backlight unit and supplied to the liquid crystal panel 110 is adjusted so that a bright line or a dark line is generated in a region of the liquid crystal panel corresponding to the hot spot region adjacent to the light incident side of the light guide plate 150 Which will be described in more detail as follows.

4A and 4B are views showing the structures of the second polarizer 180 and the first polarizer 170 of the liquid crystal display element according to the first embodiment of the present invention. The first polarizing plate 170 and the second polarizing plate 180 are generally described in order. In the present invention, however, the first polarizing plate 170 is manufactured in such a manner that an additional structure is added to the structure of the second polarizing plate 180 First, the second polarizing plate 180 will be described first and then the first polarizing plate 170 including the structure added thereto will be described.

4A, the second polarizing plate 180 of the liquid crystal display according to the first embodiment of the present invention includes a second substrate 182 and a second polarizing layer (not shown) disposed on the second substrate 182 184).

The second substrate 182 is in the form of a transparent film, and a second polarizing layer 184 is formed thereon. At this time, triacetylcellulose (TAC) or zero retardation TAC having no phase difference (Rth) may be used as the second base material 182.

The second polarizing layer 184 is a layer capable of converting natural light into arbitrary polarized light. At this time, when the incident light is divided into two polarized light components orthogonal to each other, the second polarized light layer 184 has a function of passing one polarized light component of two polarized light components and absorbing, reflecting, or scattering other polarized light components May be used. The material used for the second polarizing layer 184 is not particularly limited. For example, a polymer material containing a polyvinyl alcohol (PVA) based resin containing iodine or a dichroic dye as a main component, An O-type polarizing material in which a liquid crystal composition containing a substance and a liquid crystal compound are aligned in a certain direction, and an E-type polarizing material in which a lyotropic liquid crystal is aligned in a certain direction.

4B, the first polarizing plate 170 according to the first embodiment of the present invention includes a first substrate 172, a first polarizing layer 174 disposed on the first substrate 182, And an optical path control layer 176 constituted by a predetermined width in a predetermined region of the first polarizing layer 174 and controlling a path of light to be input.

The first substrate 172 is in the form of a transparent film, and a second polarizing layer 184 is formed thereon. At this time, TAC having no TAC or phase difference (Rth) may be used as the first substrate 172.

The first polarizing layer 174 has a function of passing one polarized light component of two polarized light components and absorbing, reflecting or scattering other polarized light components when the incident light is divided into two polarized light components orthogonal to each other Can be used. The material used for the first polarizing layer 174 is not particularly limited. For example, a polymer material containing a polyvinyl alcohol (PVA) based resin containing iodine or a dichroic dye as a main component, An O-type polarizing material in which a liquid crystal composition containing a substance and a liquid crystal compound are aligned in a certain direction, and an E-type polarizing material in which a lyotropic liquid crystal is aligned in a certain direction.

The light path control layer 176 is provided in a region where the LED 134 of the liquid crystal display element is disposed to change the path of light incident on the region to change the brightness of light incident on the liquid crystal panel 110 in this region to another region So that an image having a uniform brightness over the entire liquid crystal panel 110 can be realized. The light path control layer 176 is disposed in a region corresponding to the hot spot region of the upper surface adjacent to the light incident surface of the light guide plate 150 shown in FIG. 3, which is one side of the first polarizer 170, Is set to correspond to the hot spot area on the upper surface of the light guide plate 150, but is preferably formed to be generally about 10 mm or less. The thickness of the optical path control layer 176 is preferably 5 占 퐉 or more except for the base film.

The incident light of the light output through the hot spot region on the upper surface of the light guide plate 150 is reflected by the light guide plate 150 Is changed by the refraction and diffusion in the optical sheet 138, Since the width d of the light path control layer 176 is set to correspond to the width of the hot spot area of the light guide plate 150 because the area corresponding to the hot spot area can be calculated by the characteristics of the optical sheet Light emitted from the hot spot region on the upper surface of the light guide plate 150 is supplied to the liquid crystal panel 110 via the light path control layer 176 of the first polarizer 170. [

That is, the length (L) of the optical path control layer 176 is equal to the length of one side of the light guide plate 150, but the width d is not equal to the width of the hot spot area of the light guide plate 150, It is determined by optical properties. At this time, the length (l) direction of the light path control layer 176 is parallel to the longitudinal direction of the LED substrate 32 on which the LEDs 34 are disposed.

The hot spot area adjacent to the light incoming surface of the light guide plate 150 depends on the distance between the light incoming surface of the light guide plate 150 and the LED 134, the distance between the LEDs 134, and the directivity angle of the light output from the LED 134 And the width d of the light path control layer 176 may be varied depending on the distance between the light incoming surface of the light guide plate 150 and the LED 134, the distance between the LEDs 134, Will be determined. Since the light output through the upper surface of the light guide plate 150 changes the optical path through refraction and diffusion while passing through the optical sheet 138, the width d of the optical path control layer 176 is changed by the optical seek 138).

FIGS. 5A and 5B are views showing the structure of an optical path control layer 176 provided in the first polarizer 170 according to the first embodiment of the present invention, wherein FIG. 5A is a sectional view and FIG. 5B is a perspective view.

5A and 5B, the optical path control layer 176 includes a base film 176a, a diffusion layer 176b disposed between the prism 176b disposed on the base film 176a and the prism 176b, (176c).

The base film 176a is made of a transparent film such as polyvinyl alcohol, triacetylcellulose, or polyethylene terephthalate (PET), but a transparent film of another material can be used. The prism 176b is an acrylic resin such as PMMA (Poly-Methyl-Metacryl Acrylate) as a phase separation means for separating incident light. At this time, the prism 176b extends from one side to the other side of the base film 176a of the optical path control layer 176, and its cross section is formed in a triangular shape. At this time, the extending direction of the prism 176b is parallel to the arrangement direction (x-direction) of the LEDs 134 shown in Fig. 3 and the pitch direction (y-direction) 134). Accordingly, the light emitted from the LED 134 and input to the first polarizing plate 170 through the light guide plate 150 is incident on the inclined surface of the prism 176b, and the incident light is refracted on the inclined surface, Phase is separated. The prism 176b may be disposed at a pitch p of 10 mu m or more and the angle alpha of the vertex on the triangle of the cross section may be about 60 deg. The refractive index of the prism 176b is preferably 1 or more.

The diffusion layer 176c can be formed by distributing particles such as beads that scatter light to an adhesive layer such as a resin. At this time, the diffusion layer 176c may fill the entire region between the prisms 176b. Although the diffusing layer 176 is disposed only in the region between the prisms 176b, the diffusing layer 176 may be disposed on the vertex of the prism 176b to cover the entire prism 176b (i.e., a <b). In other words, the diffusion layer 176c is disposed on the entire region between the prisms 176b or on the entire region between the prisms 176b and on the prism 176b and on the light path control layer 170 excluding the base film 176a Since the thickness is 5 占 퐉 or more, the thickness (b) of the diffusion layer 176c is also 5 占 퐉 or more.

The optical path control layer 176 is attached to the first polarizing layer 174 by the adhesive material of the diffusion layer 176c but the optical path control layer 176 is provided with a separate adhesive layer so that the first polarizing layer 174 As shown in Fig. In the case where the adhesive layer is provided as described above, the diffusion layer 176c may be formed of a material having a diffusion property rather than an adhesive substance.

The scattered particles scattered in the diffusion layer 176c diffuse the phase-separated light incident from the prism 176b and emit light in various paths, Thereby making the luminance uniform. At this time, the diameter of the particles may be 0.5-1 탆, and the difference in refractive index from the prism 176b is preferably 0.01 or more.

6, the light output from the hot spot region of the upper surface adjacent to the light incident surface of the light guide plate 150 facing the LED 134 and input to the first polarizer 170 is reflected by the light path control layer 176, The incident light is refracted at the interface (sloped surface) of the prism 176b and the image of the light supplied to the liquid crystal panel 110 is separated. The separated light is diffused in various directions by the diffusion layer 176c and input to the first polarizing layer 176b. Accordingly, the light incident on the light path control layer 176 is mixed with the light of the other path while being changed in path, so that the light is uniformly distributed over the entire area of the light control path layer 176 and supplied to the liquid crystal panel 110 (For example, bright lines and dark lines) due to uneven brightness can be prevented in the region corresponding to the hot spot region of the light guide plate 150 (that is, the side edge region in which the LEDs 134 are arranged) .

As a result, without increasing the number of the LEDs 134 and increasing the interval between the LED 134 and the light incoming surface of the light guide plate 150, the liquid crystal display of the area corresponding to the hot spot area adjacent to the light incoming surface of the light guide plate 150 The brightness of the screen of the device can be made uniform with other areas. Accordingly, it is possible not only to prevent deterioration of the image quality of the liquid crystal display device, but also to prevent an increase in cost and an increase in bezel area due to an increase in the number of LEDs 134. [

7 is a view showing another structure of the optical path control layer 176 according to the first embodiment of the present invention.

7, in the optical path control layer 176 of this structure, the triangular vertexes of the triangular cross section of the prism 176b face downward, that is, the side of the light guide plate 150, The film 176a is disposed in the first polarizing layer 174. At this time, an adhesive layer may be provided between the base film 176a and the first polarizing layer 174 so that the optical path control layer 176 may be attached to the first polarizing layer 174.

A diffusion layer 176c is stacked between the prisms 176b and the diffusion layer 176c may be formed to cover the vertex of the prism 176b. As the diffusion layer 176c, a diffusion material including diffusion particles such as beads may be used.

The light output from the hot spot region of the light guide plate 150 among the light emitted from the LED 134 and incident on the first polarizer 170 through the light guide plate 150 is reflected by the diffusion layer 176c And the diffused light is refracted at an inclined surface of the prism 176b and input to the first polarizing layer 174. [

Therefore, light of uniform brightness is supplied to the area of the liquid crystal panel 110 corresponding to the hot spot area of the light guide plate 1500, and a bright line due to uneven brightness and a bright line It is possible to prevent dark lines from being generated.

Although not shown in the figure, in the first polarizing plate 170 of this structure, the cross section of the prism 176b may not be a complete triangle but may have a round shape having vertices of curvature.

8A and 8B are views showing the structure of the polarizing plate 270 according to the second embodiment of the present invention.

As shown in FIG. 8A, in the optical path control layer 276 of the polarizing plate 270 of this embodiment, a lenticular lens 276b is disposed on the base film 276a instead of the prism of the first embodiment. At this time, the lenticular lens 276b is made of PMMA (Poly-Methyl-Metacryl Acrylate), and the upper surface of the lens is directed to the upper direction, that is, the first polarizing layer 274 and the extending direction of each lenticular lens 276b And the pitch direction of the lenticular lens is perpendicular to the extending direction of the LED substrate (the arrangement direction of the LEDs).

A diffusion layer 276c made of an adhesive material or a diffusion material in which particles such as beads are scattered is disposed in the area between the lenticular lenses 276b. At this time, the diffusion layer 276c is also laminated on the lens surface of the lenticular lens 276b so that the diffusion layer 276c covers the lenticular lens 276b.

8B, in the polarizing plate 270 of this embodiment, the lens upper surface of the lenticular lens 276b of the optical path control layer 276 is directed downward, that is, toward the light guide plate, and between the lenticular lenses 276b A diffusion layer 276c is formed in the region. An adhesive layer may be provided between the optical path control layer 276 and the polarizing layer 274 so that the optical path control layer 276 may be attached to the polarizing layer 274.

In the light path control layer 276 of this embodiment as well as in the first embodiment, light output from the hot spot region of the light guide plate among the light emitted from the LED and incident on the polarizer 270 through the light guide plate is refracted by the lenticular lens 276b The light diffused by the diffusing layer 276c is diffracted by the diffusing layer 276c or diffused by the diffusing layer 276c is refracted by the lens surface of the lenticular lens 276b and inputted to the polarizing layer 274, The brightness of the arranged side becomes uniform with the brightness of the other region.

9 is a view showing a structure of a polarizing plate 370 according to a third embodiment of the present invention.

9, in the polarizing plate 370 of this embodiment, a prism 376b is disposed on the base film 376a, and a diffusion layer 376c is formed in the area between the prisms 376b. At this time, unlike the first embodiment and the second embodiment, in this embodiment, only a part of the region between the prisms 376b of the diffusion layer 376c is formed. That is, the diffusion layer 376c is laminated on the first polarizing layer 374 to a thickness of about 1 mu m, and the diffusion layer 376c and the prism 376b overlap each other by 1 mu m.

Although not shown in the drawing, the diffusion layer 376c may be disposed on the base film 376a to have a thickness of about 1 占 퐉, and the diffusion layer 376c and the prism 376b may overlap by 1 占 퐉. Although the prism is provided as the phase separating means in the figure, a lenticular lens may be provided, and the lenticular lens and the diffusion layer 376c may partially overlap. In addition, the prism 376b and the lenticular lens and the diffusion layer 376c may partially overlap with each other in a state in which the vertex of the prism 376b and the lenticular lens or the upper surface of the lens face the light guide plate.

In the polarizing plate 370 of this embodiment, light output from the hot spot region of the light guide plate among the light emitted from the LED and incident on the polarizing plate 370 through the light guide plate is refracted by the prism 376b and diffused by the diffusion layer 376c The brightness of the side on which the LEDs are arranged becomes equal to the brightness of the other regions by being input to the rear polarizing layer 374. [

10 is a view showing a structure of a polarizing plate 470 according to a fourth embodiment of the present invention.

In the polarizing plate 470 of this embodiment, a fine lens is applied in place of the prism and the lenticular lens used in the first and second embodiments. That is, a fine lens 476b having a pitch of several micrometers is disposed over the entire optical path control layer of the polarizing plate 470. At this time, the fine lenses 476b are regularly or irregularly arranged on the light path control layer, and refract light inputted from a hot spot region adjacent to the light incident surface of the light guide plate to change the light path. Although not shown in the figure, a diffusing layer made of an adhesive material or a diffusing material in which diffusing particles are dispersed is provided in a region between the fine lenses 476b to diffuse light refracted by the fine lens 476b, It is possible to supply light of uniform luminance to the corresponding liquid crystal panel. At this time, the diffusion layer may be formed on the upper region of the fine lens 476b.

Although the fine lens 476b is a convex lens, various lenses such as a concave lens can be used as the fine lens 476b in this embodiment.

11A and 11B are views showing the structure of a polarizing plate 570 according to a fifth embodiment of the present invention.

As shown in FIGS. 11A and 11B, the optical path control layer 476 of the polarizing plate 570 of this embodiment is composed of a diffusion layer made of an adhesive material or a diffusion material in which diffusion particles such as beads are injected. That is, in another embodiment, a prism, a lenticular lens, a fine lens, and the like are provided as phase separating means in addition to the diffusion layer. In this embodiment, the diffusion layer 576 (the light path control layer is a diffusion layer, There is no separate phase separating means.

However, in this embodiment, the diffusion layer 576 serves as phase separation means. That is, as shown in Figs. 11A and 11B, in this embodiment, the lower surface of the diffusion layer 576 itself is formed in a lens shape. Since the adhesive material of the diffusion layer 576 is made of a material having a refractive index of 1 or more, the light emitted from the hot spot region of the light guide plate and incident on the polarizing plate 570 passes through the light path control layer 576, The incident light is refracted at the surface of the lens shape and enters the light path control layer 576. The input refracted light is diffused by the diffusion particles in the light path control layer 576 and then transmitted through the polarizing layer 574 of the polarizing plate 570 And the light polarized linearly by the polarizing layer 574 is supplied to the liquid crystal panel.

As described above, in this embodiment, the light emitted from the hot spot region of the light guide plate is refracted on the surface of the diffusion layer 576 and then diffused therein, so that the input light path is changed and the liquid crystal display The brightness of light input to the region of the device becomes uniform, and image quality deficiency due to uneven brightness can be prevented.

In the figure, only the configuration in which the interface of the light path control layer 576, that is, the diffusion layer is formed by the concave lens (Fig. 10A) and the convex lens 10b is disclosed. However, the configuration of this embodiment is not limited to such a structure The interface of the diffusion layer may be a prism with its vertex pointing to the light guide plate or the liquid crystal panel, and a lenticular lens shape with the upper surface of the lens facing the light guide plate or the liquid crystal panel.

As described above, in the present invention, the light path control layer for changing the path of the light output from the hot spot region of the light guide plate to one region of the first polarizer, that is, the region corresponding to the hot spot region on the light incident surface of the light guide plate facing the LED It is possible to prevent the brightness unevenness of the screen corresponding to the hot spot area of the light guide plate from being generated.

While the invention has been described by way of example and in terms of the foregoing description, it is not intended to be limited to the specific construction of the invention. The most important characteristic of the present invention is that the optical path control layer for changing the optical path of the polarizing plate is provided to uniformize the brightness of the light supplied to the liquid crystal panel and thus can be applied to all polarizing plates having the optical path control layer .

In the above description, the optical path control layer has been described with a specific structure. However, the present invention is not limited to the polarizing plate having the optical path control layer having such a specific structure, but may be applied to a polarizing plate As shown in FIG.

Accordingly, it will be understood by those skilled in the art that various modifications and equivalent implementations of the present invention are possible, and that the scope of the present invention is not limited to any particular structure, Various modifications and improvements of those skilled in the art using the basic concept of the present invention are also within the scope of the present invention.

110: liquid crystal panel 134: LED
138: optical sheet 150: light guide plate
170, 180: Polarizing plate 176: Light path control layer
176a: base film 176b: prism
176c: diffusion layer

Claims

materials;
A polarizing layer disposed on the substrate; And
And an optical path control layer disposed in a partial region of the polarizing layer to control a path of the input light.

The optical path control apparatus according to claim 1,
A base film;
Phase separating means disposed on the base film for phase-separating input light; And
And a diffusion layer disposed on the base film.

The polarizing plate according to claim 2, wherein the phase separating means comprises at least one of a prism, a lentiginal lens and a fine lens.

The polarizing plate according to claim 2, wherein the diffusion layer comprises an adhesive material in which particles are dispersed.

The polarizer according to claim 2, wherein the diffusion layer is disposed over the entire region between the phase separation means.

The polarizing plate according to claim 5, wherein the diffusion layer covers the phase separation means.

The polarizing plate according to claim 2, wherein the diffusion layer is disposed in a part of the region between the phase separation means and overlaps with a part of the phase separation means.

The optical path control apparatus according to claim 1,
A base film; And
And a diffusion layer disposed on the base film,
Wherein the diffusion layer has a surface that is phase-separated.

The polarizing plate according to claim 8, wherein the phase-separated shape includes a prism shape, a lenticular lens shape, and a fine lens shape.

A liquid crystal panel;
A light guide plate disposed under the liquid crystal panel;
A point light source for emitting light to the liquid crystal panel through the light guide plate, the point light source emitting light to face the light incident surface on the side surface of the light guide plate;
A first polarizer disposed on a lower surface of the liquid crystal panel for polarizing light input to the liquid crystal panel and changing a path of light incident on the partial region; And
And a second polarizing plate disposed on an upper surface of the liquid crystal panel to adjust transmittance of light transmitted through the liquid crystal panel.

The liquid crystal display device according to claim 10, wherein the point light source is an LED (Light Emitting Device).

The liquid crystal display according to claim 10,
materials;
A polarizing layer disposed on the substrate; And
And a light path control layer for controlling the path of light to which the polarizing layer is disposed in a partial region.

13. The optical information recording medium according to claim 12,
A base film;
Phase separating means disposed on the base film for phase-separating input light; And
And a diffusion layer disposed on the base film.

11. The liquid crystal display element according to claim 10, wherein the light path control layer is disposed in a region corresponding to the hot spot region on the upper surface of the light guide plate.

15. The liquid crystal display device according to claim 14, wherein the hot spot region of the light guide plate is formed in a region adjacent to the light incidence surface facing the point light source.