KR20100122315A - Pattern structure of prism film for reducing moire - Google Patents

Abstract

PURPOSE: A prism film pattern structure for reducing moire is provided to prevent a moire phenomenon due to regularity of a prism by irregularly arranging the prism. CONSTITUTION: Mx rows and Ny columns are set on a prism surface. Vertexes are arranged by setting the coordinates of the vertexes according to a preset equation. An x axial pitch is controlled by the preset equation and the x and y coordinates of the vertexes of nx-th row and ny-th column are changed according to the preset equation.

Description

Prism film pattern structure for moiré reduction {PATTERN STRUCTURE OF PRISM FILM FOR REDUCING MOIRE}

The present invention relates to a prism film used for a liquid crystal display backlight unit, and more particularly, to a prism film pattern structure capable of reducing the moire phenomenon by randomizing the shape of the prism.

Typically, a liquid crystal display (LCD) is backlighted by a liquid crystal panel composed of a plurality of liquid crystal cells arranged in a matrix form and a plurality of control switches for switching a video signal to be supplied to each of these liquid crystal cells. A transmission amount of light supplied from the unit (Back Light Unit) is adjusted to display a desired image on the screen.

In order to supply light to the liquid crystal panel, the backlight unit located at the rear of the liquid crystal panel includes a lamp for generating light, a lamp housing equipped with the lamp, a light guide plate for converting light incident from the lamp into a surface light source, and a light guide plate. And optical sheets for increasing light efficiency incident to the liquid crystal panel and a reflecting plate for reflecting light emitted to the rear surface of the light guide plate to the display panel.

The prism sheet of the optical sheets includes a prism mountain having a triangular structure as shown in FIG. 1. The inclined surface of the prism mountain is formed to have a predetermined angle. Light incident on the prism sheet is refracted on the inclined surface of the prism mountain having a predetermined angle and is emitted in a direction perpendicular to the plane of the liquid crystal panel. As such, the prism sheet condenses the light diffused from the diffusion sheet in a direction perpendicular to the plane of the liquid crystal panel to increase luminance.

However, when two sheets of the above prism sheet are used in the liquid crystal display, the reflection moiré caused by the interference of the two periodic patterns occurs. This refers to a phenomenon in which the reflection image of the film pattern is visually recognized by the periodic pattern of the prism film itself. If two prism sheets are used, the brightness of the liquid crystal display may be increased within a narrow viewing angle, but there is a problem in that the moiré phenomenon occurs by reflecting more light back through a periodic pattern of the lower prism film.

The present invention relates to an optical film for a liquid crystal display backlight unit, and relates to a prism pattern and a structure generating method capable of removing the moiré effect in a structure using two prism films.

The structure of the prism pattern according to the present invention has a random shape in order to reduce the visibility of the moire interference pattern, which is formed of a prism of a random triangular, square, or hexagonal shape according to the design and manufacturing method. It is done.

The present invention sets up Nx rows and Ny columns on the prism surface,

After arranging the vertices so that the coordinates of the vertices of the nxth row and the nyth column are represented by Equation 4 below, the x-axis pitch is adjusted by Equation 5 below to adjust the nxth row and the nyth column. It provides a prism film pattern structure characterized in that the x- and y-coordinates of the vertices are changed as shown in Equation 7 below.

&Quot; (4) "

Where px is the x-axis pitch, py is the y-axis pitch,

type is 0 if nx is even, 1 if nx is odd

[Equation 5]

Where qx is the changed x-axis pitch, Δpx is a variable maximum x-axis pitch,

r is a random number in the range -1 <r <1

[Equation 7]

Where sx = 0.5 * px * (Nx-1)

In the present invention, a hexagonal prism is formed at random, and Nx rows and Ny columns are set on the prism surface, and the coordinates of the vertices of the nxth row and the nyth column are represented by Equation 4 below. After arranging the vertices so as to be shown, a prism film pattern structure is provided, wherein the y-axis coordinates of the vertices are moved to Equation 14 below.

&Quot; (4) &quot;

Where px is the x-axis pitch, py is the y-axis pitch,

type is type = 1 if ny-nx% 2 is a multiple of 3, type = 0 if not multiple of 3

(nx% 2 is the remainder of nx divided by 2)

[Equation 14]

,

는 (-D, D) 구간에서 임의로 생성된 계수,

Where K is the number of the last term in the Fourier series,

,

Is a randomly generated coefficient in the interval (-D, D),

The present invention provides a structure in which the prism is arranged in an irregular shape, thereby providing an effect that can prevent the moiré phenomenon caused by the regularity of the prism.

According to the present invention, a plurality of vertices are set on a prism film surface, and three-dimensional coordinates of X (lateral coordinates), Y (vertical coordinates), and Z (height) are given to the vertices, and the prism pattern is arranged in a random form. To form.

Basically, after setting vertex coordinates in a regular form, the vertices are moved in random directions in the X-axis direction or the Y-axis direction to have an irregular arrangement.

Hereinafter, a method of forming a prism pattern according to the present invention will be described in detail.

1. Vertex and Coordinate Set

On the surface composed of prisms, let the basic prism face be a two-dimensional face, and define the number of rows and columns in Nx, Ny, and the horizontal and vertical pitch in px and py, respectively. px is twice the vertex distance in the row direction, and py corresponds to the vertex distance in the unit column direction. Horizontal and vertical tile sizes sx and sy are defined as follows.

[Equation 1]

      sx = 0.5 * px * (Nx-1)

      sy = py * (Ny-1)

In this case, the total number of vertices is as follows.

[Equation 2]

      V = Nx * Ny

All vertices can be represented by the number ν represented by the nxth row (nx = 0, 1, ... Nx-1) and the nyth column (ny = 0, 1, ..., Ny-1).

&Quot; (3) &quot;

     ν = nx * Ny + ny

If nx is even, define valley or type = 0, and if nx is odd, define peak or type = 1.

In this case, the coordinates of each vertex may be expressed as follows.

&Quot; (4) &quot;

By the above equation, a regular virtual vertex on the prism surface can be set as shown in FIG. 2 from the general prism structure as shown in FIG. 1.

2. pitch Randomization

A method for obtaining a random prism structure that eliminates the periodicity of the prism for effectively reducing the moiré phenomenon will be described.

Let variable maximum horizontal pitch be Δpx, and define the distance between the nxth and nx + 1th vertices in the x-axis direction (i.e. the variable half horizontal pitch qx) by the following equation.

[Equation 5]

Where r is a random number in the range -1 <r <1, and the variable range of the horizontal pitch 2qx is as follows.

The following describes a method of giving a change in the z-axis direction, that is, a change in height between the nx th and nx + 1 th rows in proportion to the horizontal half pitch.

&Quot; (6) &quot;

Where θ means the angle between the xy plane and the cross section.

n If you define the coordinates of the _x-th row,

[Equation 7]

For half pitch randomization, it must be confirmed that the following equation is satisfied.

[Equation 8]

Where c is any constant in the range 0 <c <1,

[Equation 9]

For example, Zmin and Zmax can be set to -1.0 and 1.5 as default values, respectively. If the requirements [Equation 8] and [Equation 9] are not satisfied, they can be set again in the range of -1 <r <1. In this case, Equation 5 may be modified by Equation 10 below.

[Equation 10]

3A and 3B are a plan view and a sectional view of an embodiment of the present invention by silver pitch randomization.

3. Vertex Randomization

Next, the coordinates of the vertices are independently randomized.

From Equation 4 and Equation 7, each vertex can be defined as follows.

[Equation 11]

To give variation by each coordinate, it can be defined as follows.

[Equation 12]

,

,

는 각각 x, y, z 축을 따라 최대 허용 가능 변동량이고, r은 -1<r<1 범위의 난수로, 각각의 축에서 독립적으로 발생시킨다. here

,

,

Are the maximum allowable variations along the x, y, and z axes, respectively, and r is a random number in the range -1 < r <

4A and 4B are a plan view and a cross-sectional view of an embodiment of the present invention for vertex randomization by Equation (12).

4. Fourier Modulus Used Randomization Way

In the above, the basic randomization methods have been described. Hereinafter, a look at a more improved randomization method for reducing the moiré phenomenon.

It is a method of randomizing by introducing the Fouier coefficient. This is to change the vertex in the column direction using a random period function, which can be defined by the following equation.

[Equation 13]

,

는 (-A, A) 구간에서 생성된 계수이다.

이다. Where K is the number of the last term in the Fourier series,

,

Is a coefficient generated in the interval (-A, A).

to be.

 5A and 5B are plan and cross-sectional views of an embodiment of the present invention for randomizing the pitch and vertex positions of a prism using Fourier coefficients.

5. Hexagon To the structure by Randomization

(1) hexagon Vertex Set

It relates to a film, which is formed of a prism of a random hexagonal shape.

For example, if nx is even, it is defined as valley or type = 0, and if nx is odd, it is defined as peak or type = 1.

In this case, if ny-nx% 2 can be divided by 3, define type = 1 (peak). (nx% 2 is the remainder when nx is divided by 2.)

Otherwise, type = 0 (valley) for the vertices from the nth row and the nyth column.

으로 치환한다. 수학식 1을 사용하여 타일 크기는 sx=30.0, sy=17.3205를 얻을 수 있다.The height of the vertex (z-axis) is set according to the type. To complete the tile, Nx-1 must be divided by 2 and Ny-1 by 3. As a simple example, let's say Nx = 61 and Ny = 3. To create an equilateral hexagonal pyramid, py

Replace with Using Equation 1, the tile size may be obtained by sx = 30.0 and sy = 17.3205.

6A and 6B are a plan view and a cross-sectional view of a hexagonal basic prism according to the present invention, and FIGS. 7A and 7B are a plan view and a cross-sectional view of an embodiment of the present invention for a random hexagonal prism.

(2) hexagon Row On the move by Randomization

The film is characterized in that formed by a random hexagonal prism according to the column shift (colunm shift) method.

As a method of moving a vertex row using a random periodic function, it may be randomized by the following equation similarly to the expression of Equation 13.

[Equation 14]

,

는 (-D, D) 구간에서 생성된 계수이다. 그리고

이다. Where K is the number of the last term in the Fourier series,

,

Is a coefficient generated in the interval (-D, D). And

to be.

8A and 8B are a plan view and a cross-sectional view of an embodiment of the present invention randomized by the movement of a row of hexagonal prisms.

In the case of a notebook liquid crystal display device using two prism sheets overlapped with each other, when the prism film having a random shape as described above is used on the lower side, the moiré phenomenon in which the wavy pattern is seen can be prevented.

The present invention is not limited to the above embodiments, but may be manufactured in various forms, and a person skilled in the art to which the present invention pertains has another specific form without changing the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1 is a plan view showing a conventional prism structure.

Figure 2 is a plan view showing the arrangement of vertices in accordance with the present invention.

3A and 3B are plan and cross-sectional views of an embodiment of the present invention with silver pitch randomization.

4A and 4B are plan and cross-sectional views of an embodiment of the present invention for vertex randomization by Equation 12;

 5A and 5B are plan and cross-sectional views of an embodiment of the present invention for randomizing pitch and vertex positions of a prism using Fourier coefficients.

6A and 6B are a plan view and a cross-sectional view of a basic prism of hexagonal form according to the present invention.

7A and 7B are plan and cross-sectional views of an embodiment of the present invention for a random hexagonal prism.

8A and 8B are plan and cross-sectional views of an embodiment of the present invention randomized by movement of a row of hexagonal prisms.

Claims (10)

Set Nx rows and Ny columns on the prism surface, After arranging the vertices so that the coordinates of the vertices of the nxth row and the nyth column are represented by Equation 4 below, the x-axis pitch is adjusted by Equation 5 below to adjust the nxth row and the nyth column. A prism film pattern structure, wherein the x and y coordinates of the vertices are changed as shown in Equation 7 below. &Quot; (4) &quot;

Where px is the x-axis pitch, py is the y-axis pitch, type is 0 if nx is even, 1 if nx is odd [Equation 5]

Where qx is the changed x-axis pitch, Δpx is a variable maximum x-axis pitch, r is a random number in the range -1 <r <1 [Equation 7]

Where sx = 0.5 * px * (Nx-1) The method of claim 1, The prism film characterized in that the coordinates of Equation 7 generated by the random number r satisfy the following Equations 8 and 9, and if not satisfied, generate the random number r again. Pattern structure. [Equation 8]

Where c is any constant in the range 0 <c <1 [Equation 9]

Where Z _min is the minimum allowable height and Z _max is the maximum allowable height Set Nx rows and Ny columns on the prism surface, After arranging the vertices so that the coordinates of the vertices of the nxth row and the nyth column are represented by Equation 4 below, the x-axis pitch is adjusted by Equation 10 below to adjust the nxth row and the nyth column. A prism film pattern structure, wherein the x and y coordinates of the vertices are changed as shown in Equation 7 below. &Quot; (4) &quot;

Where px is the x-axis pitch, py is the y-axis pitch, type is 0 if nx is even, 1 if nx is odd [Equation 10]

Where qx is the changed x-axis pitch, Δpx is a variable maximum x-axis pitch, r is a random number in the range -1 <r <1 [Equation 7]

Where sx = 0.5 * px * (Nx-1) Set Nx rows and Ny columns on the prism surface, After arranging the vertices such that the coordinates of the vertices of the nxth row and the nyth column are represented by Equation 11 below, the prism film pattern is provided with a variation amount in each axis by Equation 12 below. rescue. [Equation 11]

here,

, xx is the changed x-axis pitch, Δpx is the variable maximum x-axis pitch, r is a random number in the range -1 <r <1, type is 0 if nx is even, 1 if nx is odd [Equation 12]

here

,

,

Is the maximum allowable variation along the x, y, and z axes, r is a random number in the range -1 <r <1, occurring independently on each axis. Set Nx rows and Ny columns on the prism surface, After arranging the vertices such that the coordinates of the vertices of the nxth row and the nyth column are represented by Equation 4 below, the prism film pattern comprising moving the x-axis coordinates of the vertex to Equation 13 below. rescue. &Quot; (4) &quot;

Where px is the x-axis pitch, py is the y-axis pitch, type is 0 if nx is even, 1 if nx is odd [Equation 13]

Where K is the number of the last term in the Fourier series,

,

Is a randomly generated coefficient in the interval (-A, A) The method of claim 5, remind

The prism film pattern structure characterized by the above-mentioned. Set Nx rows and Ny columns on the prism surface, After arranging the vertices such that the coordinates of the vertices of the nxth row and the nyth column are represented by Equation 4 below, the prism film pattern comprising moving the y-axis coordinates of the vertex to Equation 14 below. rescue. &Quot; (4) &quot;

Where px is the x-axis pitch, py is the y-axis pitch, type is type = 1 if ny-nx% 2 is a multiple of 3, type = 0 if not multiple of 3 (nx% 2 is the remainder of nx divided by 2) [Equation 14]

Where K is the number of the last term in the Fourier series,

,

Is a randomly generated coefficient in the interval (-D, D),

The method of claim 7, wherein Py is

The prism film pattern structure characterized by the above-mentioned. The prism film provided with the prism film pattern in any one of Claims 1-8. A backlight unit for a liquid crystal display device comprising the prism film of claim 9.

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