KR20120011185A - Liquid crystal display device using light diffusion lens - Google Patents

Abstract

PURPOSE: A liquid crystal display apparatus using a light diffusion lens is provided to reduce the manufacturing costs of a backlight unit by reducing the number of an LED(Light Emitting Diode) package. CONSTITUTION: The thickness of a light diffusion lens is the thinnest at the center of an outer surface. Air is filled between the inner surface of the light diffusion lens and a PCB(Printed Circuit Board). Light emitted by the inner surface passes through the center unit(111a) of the outer surface. The total reflection unit of the outer surface(111b) totally reflects the light. The side unit of the outer surface inflects the light according to an incidence angle.

Description

Liquid crystal display using light diffusion lens {LIQUID CRYSTAL DISPLAY DEVICE USING LIGHT DIFFUSION LENS}

The present invention relates to a liquid crystal display device using a light diffusing lens.

BACKGROUND ART Liquid crystal display devices have tended to be gradually widened due to their light weight, thinness, and low power consumption. Liquid crystal displays are widely used as portable computers such as notebook PCs, office automation equipment, audio / video equipment, indoor and outdoor advertising display devices, and the like. The LCD displays an image by controlling an electric field applied to the liquid crystal layer to modulate the light incident from the backlight unit.

The liquid crystal display device includes a liquid crystal display panel for displaying video data, and a back light unit for irradiating light to the liquid crystal display panel. The liquid crystal display panel and the backlight unit are assembled in a stacked state to form a liquid crystal module. The liquid crystal module further includes a guide / case member for fixing the liquid crystal display panel and the backlight unit, and a driving circuit board of the liquid crystal display panel.

The backlight unit is roughly divided into a direct type and an edge type. The direct type backlight unit has a structure in which a plurality of light sources are disposed under the liquid crystal display panel, and the edge type backlight unit has a light source disposed to face the side of the light guide plate, and a plurality of optical sheets are disposed between the liquid crystal display panel and the light guide plate. It has a structure.

1 is a cross-sectional view illustrating a liquid crystal module including a direct type backlight unit. The direct type backlight unit has a structure in which a plurality of optical sheets 5 and a diffusion plate 4 are stacked below the display panel 6 and a plurality of light sources are disposed below the diffusion plate 4. Light generated from the light sources is scattered and refracted through the diffusion plate 4 and the optical sheets 5 to spread to the front surface of the display panel 6.

Recently, a light emitting diode (Light Emitting Diode, hereinafter referred to as "LED"), which has advantages such as high efficiency, high brightness, and low power consumption, has been in the spotlight as a light source of a backlight unit. The optical gap is defined as the distance (G) between the PCB (2) and the diffuser plate (4). The LED has a narrow optical spread angle (θ), so that the optical gap (G) of constant height is not secured. Otherwise, there is a problem that luminance unbalance occurs. For example, when the distance between the LED package 1 is long as shown in FIG. 2 or when the optical gap G of a constant height is not secured as shown in FIG. 3, the light from the LED package 1 is diffused into the diffuser plate 4. Because it does not touch a part of the), hot spot mura may appear, where only the light hits it. Therefore, in the case of the direct type backlight unit, since the optical gap G having a predetermined height must be secured, the thickness of the backlight unit becomes thick.

In order to solve this problem, a light diffusing lens capable of widely diffusing light generated from the LED package 1 has been proposed. As one example of the light diffusing lens, the light diffusing lens disclosed in Japanese Patent Laid-Open No. 10-2006-0051465 is known. However, in the light diffusing lens disclosed in Korean Patent Laid-Open Publication No. 10-2006-0051465, when the LED package 1 having a light emitting surface having a rectangular shape in which the ratio of the length and the length of the width is not 1: 1, as shown in FIG. The distribution of light passing through the diffusion lens is an elliptical light distribution, not circular.

5 shows the distribution of light passing through the light diffusing lens shown in the diffuser plate. When the light distribution is elliptical in the structure T in which the LED package 1 is arranged in a triangular shape as shown in FIG. 5, the uniformity of light at the point A and the point B is different. In the case where the uniformity of light at the A and B points is different, it is difficult to make the uniformity of the light at the A and B points equal even when using the optical sheets, so that an unbalance in luminance occurs.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display using a light diffusing lens without luminance unbalance in the light emitting surface of a rectangular LED package.

In order to achieve the above object, the liquid crystal display device using the light diffusing lens of the present invention includes an LED package having a rectangular light emitting surface; A PCB on which the LED package is mounted; And a light diffusing lens attached to the PCB to cover the LED package, wherein the light diffusing lens is formed of a transparent material having an outer surface and an inner surface, and the inner surface includes an elliptical cross section concave toward the outer surface. The outer surface includes a central portion concave toward the inner surface and facing the center of the light emitting surface of the LED package, a total reflection portion formed around the central portion, and a side portion extending below the total reflection portion. The thickness of the lens is thinnest at the center of the outer surface, the space between the inner surface and the PCB is filled with air, the center portion passes light incident through the inner surface as it is, and the total reflection portion is the inner portion. Total reflection of the light incident through the surface, and the side portion refracts the light incident through the inner surface according to the incident angle. Characterized in that for spreading.

According to the present invention, a light diffusing lens is disposed in each of the LED packages having a light emitting surface having a rectangular shape, and the light diffusing lens is designed to have a circular distribution of light passing through the light diffusing lens. As a result, the present invention can minimize the unbalance of luminance in the LED package array. In addition, the present invention can reduce the optical gap can reduce the thickness of the backlight unit, it is possible to reduce the number of LED packages can reduce the backlight manufacturing cost.

1 is a cross-sectional view illustrating a liquid crystal module including a direct type backlight unit.
2 and 3 are cross-sectional views showing an optical gap of the direct type backlight unit.
4 is a diagram illustrating light distribution of an LED package in which a conventional light diffusing lens is disposed.
5 is a diagram illustrating a light distribution of an LED package array in which a conventional light diffusing lens is disposed.
6 is a cross-sectional view illustrating a liquid crystal module including a backlight unit using a light diffusing lens according to an exemplary embodiment of the present invention.
7 is a perspective view illustrating a light emitting area of an LED package.
8 is a cross-sectional view illustrating a light diffusing lens according to an exemplary embodiment of the present invention.
9 is a cross-sectional view illustrating the diffusion of light through the light diffusing lens of FIG. 8.
FIG. 10 is a perspective view illustrating a bottom surface of the light diffusing lens of FIG. 8.
FIG. 11 is a perspective view illustrating an outer surface shape of the light diffusing lens of FIG. 8.
12 is a perspective view illustrating an inner surface shape of the light diffusing lens of FIG. 8.
FIG. 13 is a plan view illustrating an inner surface and an LED package of the light diffusing lens of FIG. 8.
14 is a view showing a light distribution of the LED package in which the light diffusing lens according to the embodiment of the present invention is disposed.
FIG. 15 is a view illustrating a light distribution of an LED package array in which a light diffusing lens is disposed according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Like numbers refer to like elements throughout. In the following description, when it is determined that a detailed description of known functions or configurations related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Component names used in the following description are selected in consideration of ease of specification, and may be different from actual product names.

6 is a cross-sectional view illustrating a liquid crystal module including a backlight unit using a light diffusing lens according to an exemplary embodiment of the present invention. Referring to FIG. 6, the liquid crystal module of the present invention includes a display panel 106, a driver of a display panel 106 (not shown), a backlight unit, a guide / case member for supporting the backlight unit, and the like. The backlight unit of the present invention includes an LED package 101, a PCB 102, a reflective sheet 103, a diffuser plate 104, optical sheets 105, and the like, and a light diffusion lens on the LED package 101. 110 is disposed.

LED package 101 of the present invention has a light emitting surface of a rectangular shape, the ratio of the horizontal and vertical length is not 1: 1. As shown in FIG. 7, the LED package 101 emits light having the maximum light emission brightness in a vertical direction (V) with respect to the horizontal light emitting surface, and has approximately the maximum light emission brightness at a left and right azimuth angle of 60 degrees based on the vertical direction (V). 50% brightness. Therefore, the light passing through the light diffusion lens 110 from the LED package 101 is shown as shown in FIG.

Each of the outer surface 111 and the inner surface of the light diffusing lens 110 is processed into a specific shape, the inner surface 112 of the lens primarily refracts the light from the LED package 101, the outer surface of the lens 111 secondly refracts light primarily refracted by the inner surface 112 of the lens. Hereinafter, the light diffusing lens 110 will be described in detail with reference to FIGS. 8 to 15.

8 is a cross-sectional view illustrating a light diffusing lens 110 according to an exemplary embodiment of the present invention, and FIG. 9 is a cross-sectional view showing light diffusion through the light diffusing lens 110 of FIG. 8. Referring to FIG. 8, the light diffusion lens 110 may include an outer surface 111 of the lens, an inner surface 112 of the lens, a bottom surface 113 of the lens, and an inner surface 112 and a bottom surface of the lens. It includes an inner space 114 that is a space.

8 and 9, the outer surface 111 of the lens extends downward from the total center portion 111a concave toward the inner surface, the total reflection portion 111b and the total reflection portion 111b formed convexly around the central portion 111a. It is divided into side parts 111c. The center portion 111a allows the light incident through the inner surface 112 of the lens to proceed L1 without refraction. Light L1 propagated through the center portion 111a is incident on the diffusion plate 104. The total reflection part 111b totally reflects the light incident through the inner surface 112 of the lens. The light totally reflected by the total reflection part 111b travels toward the bottom surface of the lens (L2), is reflected by the PCB 102 or the reflective sheet 103 and is incident on the diffusion plate 104. The side portion 111c refracts light incident through the inner surface 112 of the lens according to its incident angle to diffuse (L3). The light refracted by the side portion 111c is reflected by the reflective sheet 103 and is incident on the diffuser plate 104.

As a result, light of a part of the light diffusing lens 110 proceeds as it is (L1) and is incident on the diffuser plate 104, and is totally reflected by the total reflection part 111b of the light diffusing lens 110, or the side part 111c. The large amount of light L2 and L3 refracted by the light is reflected by the PCB 102 or the reflective sheet 103 and incident on the diffuser plate 104. Therefore, in the case of the liquid crystal display device using the light diffusing lens 110 of the present invention, since the light of the LED package can be widely spread, even if the optical gap (G) is reduced or the number of LED packages is reduced, the luminance imbalance is reduced. You can implement a screen that does not exist.

The inner surface 112 of the lens has the shape of an elliptical cross section concave toward the outer surface 111, and therefore, the thickness of the light diffusing lens 110 is the thinnest at the central portion 111a of the outer surface 111. Light directed toward the center of the inner surface 112 of the lens is not refracted, and the light travels in the vertical direction L1 through the center portion 111a of the outer surface 111 of the lens.

The bottom surface 113 of the lens is bonded to the PCB 102 and serves to support the light diffusion lens 110. The adhesion of the light diffusing lens 110 and the PCB 102 is performed by applying an ultraviolet curing adhesive to the PCB 102 and then attaching the light diffusing lens 110 and then applying ultraviolet rays to cure the adhesive.

The bottom surface 113 of the lens is connected to the outer surface 111 and the inner surface 112 of the lens. Between the bottom surface 113 of the lens and the inner surface 112 of the lens may lead to a stepped shape 115 to facilitate receiving the LED package 101.

The inner space 114 is a space between the inner surface 112 and the bottom surface 113 of the lens, the LED package 101 is located in the center of the inner space 114. The remaining space after storing the LED package 101 in the internal space 114 may be filled with an air layer.

FIG. 10 is a perspective view illustrating a bottom surface of the light diffusing lens 110 of FIG. 8. The bottom surface 113 of the light diffusing lens 110 has an elliptical shape. Since the LED package 101 has a light emitting surface having a rectangular shape in which the ratio of the width and the length is not 1: 1, the light diffusion lens 110 is used to uniformly diffuse the light from the LED package 101 in a circular shape. Bottom surface 113 of) is formed in an elliptical shape rather than a circular shape. Detailed description thereof will be described later with reference to FIG. 13.

FIG. 11 is a perspective view illustrating a shape of an outer surface 111 of the light diffusing lens 110 of FIG. 8. Referring to FIG. 11, the light diffusing lens 110 has a form of an aspheric lens. Aspherical lens means a lens whose surface is aspherical rather than spherical or flat. The shape of the outer surface 111 of the lens is a shape implemented by rotating the curve (C) represented by Equation 1 360 degrees as shown in FIG.

In Equation 1, r is the radius of the lens bottom surface, c is the curvature of the curved surface, k is the conic constant, A is the aspherical coefficient of the fourth order term, B is the aspherical coefficient of the sixth term, C is the aspherical surface of the eighth term The coefficient and D are aspherical coefficients of the tenth order. The curvature c of the curved surface refers to the curvature of the concave shape toward the inner surface of the center portion 111a of the outer surface 111 of the lens. The fourth to tenth terms are defined by the aspherical shape of the total reflection portion 111b and the side portion 111c, and the aspherical coefficients A, B, C, and D are necessary to design the total reflection portion 111b and the side portion 111c. Coefficients.

In Equation 1, the radius of the lens bottom surface is greater than 0.25 and has a value less than or equal to 5, and the koenic constant k is greater than -12 and has a value less than or equal to zero. In addition, aspherical coefficient A has a value greater than -0.01 and less than or equal to 0, aspheric coefficient B has a value greater than 0 and less than or equal to 0.0001, and aspheric coefficient C is greater than -0.000001 and less than or equal to 0. Aspheric coefficient D has a value greater than 0 and less than or equal to 0.000000001. In addition, in order to make the aspherical surface of the outer surface 111 of the lens more precise, a higher order term having aspherical coefficients other than A, B, C, and D may be added.

FIG. 12 is a perspective view illustrating an inner surface 112 of the light diffusing lens 110 of FIG. 8. Referring to FIG. 12, the shape of the inner surface 112 of the lens is formed in an elliptic hemispherical shape. The shape of the inner surface 112 of the lens may be expressed as Equation 2.

Referring to FIG. 12, in Equation 2, x is the major axis radius of the elliptic hemisphere, y is the minor axis radius of the elliptical hemisphere, c _x is the curvature of the surface in the x direction, c _y is the curvature of the surface in the y direction, k _x is x Direction conic constant, k _y means the conic constant in the y direction. In addition, higher order terms with aspherical coefficients may be added to make the aspherical surface of the inner surface 112 of the lens more precise. A higher order term in which aspheric coefficients are added to Equation 2 is shown in Equation 3.

In Equation 3, A _x is a fourth aspherical coefficient in the x direction, A _y is a fourth aspherical coefficient in the y direction, B _x is a sixth aspherical coefficient in the x direction, B _y is a sixth aspherical coefficient in the y direction, C _x means the 8th order aspherical coefficient in the x direction, C _y means the 8th order aspherical coefficient in the y direction. In order to further refine the aspherical surface of the inner surface 112 of the lens, higher order terms with aspherical coefficients other than A _x , A _y , B _x , B _y , C _x , and C _y can be added. The shape of the inner surface 112 of the light diffusing lens depends on the size of the light emitting surface of the LED package 101, which will be described later with reference to FIG.

FIG. 13 is a plan view illustrating the inner surface 112 and the LED package 101 of the light diffusing lens 110 of FIG. 12. Referring to FIG. 13, the major axis radius x and the minor axis radius y of the elliptical hemisphere are related to the length of the light emitting surface of the rectangular LED package 101. 13 is a plan view of the light emitting surface of the rectangular LED package 101 as viewed from above. The long side l at the light emitting surface of the LED package 101 corresponds to the major axis radius x of the ellipsoidal hemisphere, and the short side s of the length corresponds to the minor axis radius y of the oval hemisphere. The ratio (x / y) of the major axis radius (x) and the minor axis radius (y) of the oval hemisphere is 0.2 of the ratio (l / s) of the length of the long side (l) and the short side (s) of the LED package 101. Pear to 2 times. Therefore, by adjusting the long axis radius (x) and the short axis radius (y) of the oval hemisphere according to the horizontal and vertical length of the light emitting surface of the rectangular LED package 101, the light from the LED package 101 in a circular form. It can spread uniformly. As a result, the light diffusion lens 110 optimized for the light emitting surface of the rectangular LED package 101 may be designed.

The outer surface 111 and the inner surface 112 of the light diffusing lens 110 have a smooth curved surface, and the light from the LED package 101 passes through the light diffusing lens 110 while the outer surface 111 of the lens is ) And the inner surface 112 respectively. In this case, since the refraction angles of the short wavelength light of the blue color and the long wavelength light of the red color are different, the problem of color scattering may occur. In order to solve this problem, it is possible to form a micro pattern that roughens the surfaces of the outer surface 111 and the inner surface 112 of the lens, or to remove color dispersion by applying a scattering agent coating.

The micro pattern is to corrode the smooth mold mold of the light diffusing lens 110 in a regular or irregular pattern. The micropattern forming method is to form a micropattern on the surface of the light diffusing lens 110 that is made by injection molding, and the surface of the light diffusing lens 110 is roughened by a regular or irregular pattern.

The scattering agent coating is to coat a surface of the light diffusing lens 110 with a resin containing scattering beads. The scattering agent coating method is to produce a scattering effect by coating the scattering beads on the surface of the light diffusing lens 110 made by injection molding, the surface of the light diffusing lens 110 through the scattering agent coating becomes rough.

Micro pattern or scattering agent coating is applied to both the outer surface 111 and the inner surface 112 of the light diffusing lens 110, or the micro pattern or scattering agent coating on only one surface of the outer surface 111 and the inner surface 112 can do. However, each of the outer surface 111 and the inner surface 112 may be applied only one of the micro-pattern or scattering agent coating.

14 is a view illustrating a light distribution of the LED package 101 in which the light diffusing lens 110 is disposed according to an embodiment of the present invention, and FIG. 15 is a light diffusing lens 110 according to an embodiment of the present invention. A diagram showing the light distribution of the LED package array. Referring to FIG. 14, the distribution of light appearing from the LED package 101 through the light diffusing lens 110 is circular rather than elliptical. Since the light distribution is circular, the uniformity of the light at the A and B points adjacent to each other in the circular light distribution is substantially the same in the structure T in which the LED package 101 is arranged in a triangle as shown in FIG. 15. Therefore, when the distribution of light appearing in the diffuser plate 104 from the LED package 101 through the light diffusing lens 110 is circular, light without luminance unbalance is irradiated onto the front of the display panel through the optical sheets 105. Can be.

On the other hand, the light diffusion lens 110 is a transparent plastic lens may be made of PMMA (Polymethylmethacrylate) or polycarbonate (Polycarbonate) as a material. The refractive index of the light diffusion lens 110 made of polymethylmethacrylate (PMMA) or polycarbonate is 1.49.

Referring to FIG. 6, the liquid crystal display device using the light diffusing lens 110 according to the present invention includes a display panel 106, a driver of a display panel 106 (not shown), and the light diffusing lens described with reference to FIGS. 8 to 15. And a direct backlight unit in which the 110 is disposed on the LED package 101, and a guide / case member for supporting the backlight unit.

In the display panel 106, a liquid crystal layer is formed between two glass substrates. A plurality of data lines and a plurality of gate lines intersect with the lower glass substrate 106b of the display panel 106. Liquid crystal cells are arranged in a matrix form on the display panel 106 due to the intersection structure of the data lines and the gate lines. In addition, a thin film transistor (TFT), a pixel electrode of a liquid crystal cell connected to the TFT, and a storage capacitor are formed on the lower glass substrate 106b of the display panel 106. . The liquid crystal cells are driven by an electric field generated by the potential difference between the data voltage supplied to the pixel electrode through the data lines and the common voltage supplied to the common electrode to adjust the amount of light transmitted through the display panel 106.

The black matrix, the color filter, and the common electrode are formed on the upper glass substrate 106a of the display panel 106. The common electrode is formed on the upper glass substrate 106a in a vertical electric field driving method such as twisted nematic (TN) mode and vertical alignment (VA) mode, and has an in plane switching (IPS) mode and a fringe field switching (FFS) mode. In the same horizontal electric field driving method, a pixel electrode is formed on the lower glass substrate 106b. On each of the upper glass substrate 106a and the lower glass substrate 106b of the display panel 106, a polarizing plate is attached and an alignment film for setting the pretilt angle of the liquid crystal is formed on the inner surface of the display panel 106 in contact with the liquid crystal.

The driving circuit board of the display panel 106 (not shown) includes a gate driver, a data driver, and a timing controller. The data driver stores a shift line for sampling a clock signal, a register for temporarily storing digital video data (RGB), and one line of data in response to a clock signal from the shift register, and simultaneously outputs the stored one line of data. A digital / analog converter for selecting a positive / negative gamma voltage with reference to a gamma reference voltage corresponding to a digital data value from the latch, and analog data converted by the positive / negative gamma voltage A plurality of data drive integrated circuits each include a multiplexer for selecting a supplied data line and an output buffer connected between the multiplexer and the data line. The data driver latches the digital video data RGB under the control of a timing controller, and converts the latched digital video data RGB into a positive / negative analog data voltage using a positive / negative gamma compensation voltage. Then supply it to the data lines.

The gate driver comprises a plurality of gate drive integrated circuits each including a shift register, a level shifter for converting an output signal of the shift register into a swing width suitable for driving a TFT of a liquid crystal cell, an output buffer, and the like. Under the control of the timing controller, the gate driver sequentially outputs gate pulses (or scan pulses) having a pulse width of approximately one horizontal period and supplies them to the gate lines.

The timing controller receives digital video data RGB and timing signals Vsync, Hsync, DE, and DCLK input from a system board on which an external video source is mounted, and supplies digital video data RGB to the data driver. The timing signals Vsync, Hsync, DE, and DCLK include a vertical synchronization signal Vsync, a horizontal synchronization signal Hsync, a data enable signal DE, a dot clock signal DCLK, and the like. The timing controller generates timing control signals DDC and GDC for controlling the operation timing of the data driver and the gate driver based on the timing signals Vsync, Hsync, DE, and DCLK from the system board. The timing controller inserts an interpolation frame between the frames of the input video signal input at a frame frequency of 60 Hz and multiplies the data timing control signal DDC and the gate timing control signal GDC to 60 × N, where N is two or more. The frequency of Hz may control the operation of the data driver and the gate driver.

The direct type backlight unit of the present invention includes an LED package 101, a PCB 102, a reflective sheet 103, a diffuser plate 104, optical sheets 105, and the like, and includes light on the LED package 101. The diffusion lens 110 is disposed. In the direct backlight unit of the present invention, a plurality of optical sheets 105 and a diffusion plate 104 are stacked below the display panel 106 and a plurality of LED packages 101 are disposed below the diffusion plate 104. Has a structure. The light diffusing lens 110 is disposed on each LED package 101.

The LED package 101 receives an electrical signal from the light source driver through the PCB 102 to turn on and turn off the LED. The PCB 102 is formed with a circuit for electrically connecting the LED package 101 and the light source driver. PCB 102 may be formed of a metal PCB, and the metal PCB may be made of aluminum to favor heat dissipation.

A reflective sheet 103 capable of reflecting light back from the light diffusing lens 110 may be adhered to the bottom cover 107. As shown in FIG. 9, the light L2 and the side surface 111c are refracted toward the bottom surface 113 of the lens through the total reflection portion 111b of the outer surface 111 of the light diffusion lens 110 in the horizontal direction. The refracted light L3 is reflected back through the PCB 102 or the reflective sheet 103 and is incident to the diffuser plate 104.

The diffuser plate 104 includes beads to diffuse light from the LED packages 101. The diffuser plate 104 diffuses light incident from the LED packages 101 to make the luminance of the display surface uniform. The optical sheets 105 include at least one prism sheet and at least one diffusion sheet to diffuse light incident from the diffuser plate 104 and at an angle substantially perpendicular to the light incident surface of the display panel 106. Refract the path of light. The optical sheets 105 may include a dual brightness enhancement film (DBEF).

The guide / case member includes a bottom cover 107, a guide panel 108, a case top 109, and the like. The bottom cover 107 is made of a metal of a rectangular frame to surround the side and bottom of the backlight unit. The bottom cover 107 is made of a high strength steel sheet, for example, an electrogalvanized steel sheet (EGI), stainless steel (SUS), galvalume (SGLC), aluminum plated steel sheet (aka ALCOSTA), tin plated steel sheet (SPTE), etc. Can be.

The guide panel 108 includes a step surface facing the side of the display panel 106 and the backlight unit to surround the top edge and the side of the display panel 106 and surround the side of the backlight unit. The stepped portion of the guide panel 108 supports the display panel 106 from below and secures a panel gap between the display panel 106, the diffusion plate 104, and the optical sheets 105.

The case top 109 has a structure surrounding the top and side surfaces of the guide panel 108. The case top 109 is fixed to at least one of the guide panel 108 and the bottom cover 107 by a hook or a screw.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the present invention should not be limited to the details described in the detailed description, but should be defined by the claims.

1, 101: LED package 2, 102: PCB
3, 103: reflection sheet 4, 104: diffusion plate
5, 105: optical sheets 6, 106: display panel
6a, 106a: upper glass substrate 6b, 106b: lower glass substrate
7, 107: bottom cover 8, 108: guide panel
9, 109: case top 110: light diffusing lens
111: outer surface of the lens 111a: center portion
111b: total reflection 111c: side
112: inner surface of the lens 113: bottom surface of the lens
114: internal space G: optical gap

Claims (8)

An LED package having a rectangular emitting surface;
A PCB on which the LED package is mounted; And
A light diffusing lens adhered to the PCB to cover the LED package,
The light diffusing lens is made of a transparent material having an outer surface and an inner surface,
The inner surface comprises an elliptical cross section concave towards the outer surface,
The outer surface includes a concave center portion concave toward the inner surface and facing the center of the light emitting surface of the LED package, a total reflection portion formed around the center portion, and a side portion extending below the total reflection portion,
The thickness of the light diffusing lens is the thinnest at the center of the outer surface,
The space between the inner surface and the PCB is filled with air,
The central portion passes light incident through the inner surface as it is, the total reflection portion totally reflects light incident through the inner surface, and the side portion refracts and diffuses the light incident through the inner surface according to the incident angle. Liquid crystal display using a light diffusion lens, characterized in that. The method of claim 1,
The outer surface is

The shape is implemented by rotating a curve that satisfies 360 degrees,
The curve is a function of z ₁ , where r is the radius of the bottom surface of the light diffusing lens, c is the curvature of the center portion of the outer surface, k is the conic constant, and the shape of the center portion is defined as c. The shape of the total reflection portion and the side portion is defined by the fourth to tenth term,
R is greater than 0.25 and equal to or less than 5, k is greater than -12 and equal to or less than 0, A is greater than -0.01 and equal to or less than 0, and B is greater than 0 and less than or equal to 0.0001 And C is greater than -0.000001 and less than or equal to 0, and D is greater than 0 and less than or equal to 0.000000001. The method of claim 1,
The shape of the inner surface,

Satisfying
The shape is a function of z ₂ , wherein x is the major axis radius of the elliptic hemisphere, y is the minor axis radius of the elliptic hemisphere, c _x is the curvature of the curved surface in the direction of the major axis radius, and c _y is the minor axis radius. Curvature of the curved surface in the direction, k _x is a conic constant in the radial direction of the major axis, k _y is a conic constant in the minor axis radial direction, the liquid crystal display using a light diffusing lens. The method of claim 3, wherein
And the ratio between the long axis radius and the short axis radius is 0.2 to 2 times the ratio of the length of the long side and the short side of the LED package. The method of claim 1,
The light diffusion lens is made of any one of acrylic PMMA and polycarbonate. The method of claim 1,
The LED package is a liquid crystal display using a light diffusing lens, characterized in that for emitting a light of 50% of the maximum light emission luminance at an angle of 60 ° to 120 ° in the vertical direction with respect to the horizontal light emitting surface. The method of claim 1,
And a reflective sheet reflecting the totally reflected or refracted light through the light diffusing lens. The method of claim 1,
And roughening the surface of the outer surface and / or the inner surface to prevent color dispersion of light refracted from the light diffusing lens.

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