WO2015046905A1 - Condensing-type optical sheet - Google Patents

Abstract

The present invention relates to a condensing-type optical sheet and, more particularly, to a condensing-type optical sheet that can minimize a reduction in brightness while improving color uniformity by virtue of the curvature of a cross-sectional sloped portion of a three-dimensional structure formed on a structure layer of the condensing-type optical sheet.

Description

Condensing Optical Sheet

The present invention relates to a light collecting optical sheet used in a liquid crystal display.

As the industrial society develops into an advanced information age, the importance of the electronic display device as a medium for displaying and transmitting various information is increasing day by day. CRT (Cathode Ray Tube), which has been widely used in the past, has limitations due to large installation space, which makes it difficult to increase the size. Therefore, such as liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), and organic EL It is being replaced by various flat panel display devices. Among such flat panel display devices, in particular, in the case of liquid crystal display devices (LCDs), due to the advantages of thin, light, and low power consumption as a technology-intensive device in which liquid crystal and semiconductor technologies are combined, its structure and manufacturing technology have been researched and developed. In addition to the areas where liquid crystal displays have been widely used, such as notebook computers, desktop computer monitors, and portable personal communication devices (PDAs and mobile phones), large-sized technologies are gradually exceeding their limitations. It is being applied as a new display device that can replace CRT, which is synonymous with display, as it is being applied to large TV of TV.

In the liquid crystal display (LCD) device, since the liquid crystal itself cannot emit light, a separate light source is installed at the rear of the device, and the intensity of the light passing through the liquid crystal installed in each pixel is controlled to adjust the light and shade. Implement In more detail, the liquid crystal display device is a device for controlling the light transmittance by using the electrical properties of the liquid crystal material, the uniformity and the directionality is controlled by passing through various functional prism films or sheets by emitting light from the light source lamp on the back of the device Indirect light emission method that realizes the image of red, blue, green (R, G, B) by passing light through color filter and controls the light and shade of each pixel by electric method As a display device, a light emitting device that provides a light source is an important component for determining image quality such as brightness and uniformity of a liquid crystal display device.

As the light emitting device, a backlight unit (BLU) is widely used. In general, a diffuser plate, a diffusion sheet, and a prism are used to sequentially emit light emitted by using a plurality of light sources such as a cold cathode fluorescent lamp (CCLF). A sheet such as a sheet is passed through to reach the liquid crystal panel. Here, the diffusion sheet performs a function of obtaining a uniform light intensity over the entire screen, and at the same time concealing a device such as a light source mounted under the diffusion sheet from the front. The prism sheet, on the other hand, performs an optical path control function for causing the light beams from various directions passing through the diffusion sheet to be converted into a range of viewing angle θ suitable for the viewer to recognize the image.

Meanwhile, the demand for high quality and high reliability products is increasing in the display market in recent years, and in particular, the uniformity of color according to the field of view has emerged as an important factor.

In this regard, in the case of a conventional optical sheet having a vertex angle of 90 degrees and a straight hypotenuse formed on the front surface of the optical sheet, the angle of the prism pattern may be designed at an obtuse angle to improve the uniformity of color depending on the field of view. An attempt was made to give a round.

However, such a prior art has a slight deterioration in luminance, and the effect of improving the uniformity of color is insignificant, such as the uniformity of color according to the viewing angle is improved to 1/1000 level.

In order to improve this, Korean Patent Publication No. 10-2011-0011931 (published on Feb. 9, 2011) previously filed and filed by the present applicant has a three-dimensional structure of the structural layer having a streamlined longitudinal section and including an inclined portion based on one peak point. The inclined portion is described with respect to the optical sheet having a form that is part of the virtual first and second circumferences. Such an optical sheet was advantageous in terms of not causing a yellow band or rainbow phenomenon.

An object of the present invention is to provide a light collecting type optical sheet capable of minimizing luminance degradation and improving color uniformity according to a field of view.

Accordingly, the present invention is a first preferred embodiment, the base layer; And a structural layer formed on one side or both sides of the base layer and having a plurality of three-dimensional structures arranged thereon, wherein the three-dimensional structure of the structural layer has a longitudinal cross-section of which is slanted and extends in both directions based on one peak point. Wherein the inclined portion is symmetrical or asymmetrical with respect to the peak point, and each inclined portion is part of the circumference of the overlapping imaginary first ellipse and the second ellipse, wherein the first ellipse and the second ellipse are respectively represented by Equation 1 Provided is a light collecting type optical sheet characterized in that the shape is defined by.

<Equation 1>

Wherein x and y are each real, a and b are integers 0 <a <b <10 and a: b is from 2: 1 to 100: 1.

According to the embodiment, the inclined portion may include one of the contacts formed by overlapping the first ellipse and the second ellipse as a peak point.

The inclined portion according to the embodiment may be a part of the first ellipse and the second ellipse adjacent to the hypotenuse of the triangle formed by connecting three of the contacts formed by overlapping the first ellipse and the second ellipse.

In the first ellipse and the second ellipse according to the embodiment, each major axis is orthogonal to each other, and the center of each major axis may be overlapped.

The center of the base of the three-dimensional structure according to the embodiment and the center of the long axis of each of the first ellipse and the second ellipse may coincide with each other.

The substrate layer according to the embodiment may be formed of a resin selected from polyethylene terephthalate resin, polymethyl methacrylate resin, polycarbonate resin, polypropylene resin, polyethylene resin, polystyrene resin and styrene-acrylic copolymer resin.

The structural layer according to the embodiment may be formed of a resin selected from a polymer resin including an ultraviolet curable resin or a thermosetting resin.

The present invention also provides a backlight unit assembly including the light converging optical sheet as a second preferred embodiment.

According to the present invention, by optimizing the curvature of the pattern including the streamline formed on the structural layer of the light converging optical sheet, it is possible to provide a light converging optical sheet having a uniform uniformity of color according to the viewing angle while minimizing luminance deterioration. There is.

1 shows an elliptic graph according to Equation 1 which defines the shape of the first ellipse and the second ellipse associated with the inclination curvature of the three-dimensional structure formed in the structural layer of the light converging optical sheet according to the present invention.

Figure 2 shows a cross-sectional shape of the three-dimensional structure formed in the structural layer of the light collecting optical sheet according to the present invention.

Figure 3 shows a schematic diagram in which the cross-section of the three-dimensional structure is formed by the first ellipse and the second ellipse in the light collecting optical sheet according to the present invention.

Figure 4 shows a schematic diagram of the first ellipse and the second ellipse orthogonally overlap in the light collecting optical sheet according to the present invention.

FIG. 5 is a scanning electron microscope (SEM) photograph of a three-dimensional cross section formed in a structural layer of a light collecting optical sheet according to Examples and Comparative Examples of the present invention (magnification: (a) Cross section × 500, Left Slop or Right Slop × 3,000; (b) Cross section × 500, Left Slop or Right Slop × 3,000; (c) Left × 4,000, Right × 500; (d) Left × 4,000, Right × 500; (e) Left × 1,500, Right × 300 (f) left x 1,500 and right x 500).

Figure 6 shows the color coordinate (u ', v') CIE chromaticity diagram as a reference when measuring the color uniformity for the light collecting optical sheet in the present invention.

Figure 7 shows an example of the inclined portion of the three-dimensional structure formed by the first ellipse and the second ellipse in the light collecting optical sheet according to the present invention.

<Description of the code>

10: solid structure

11: peak, 12: slope

21: first ellipse, 22: second ellipse, 23: long axis

Hereinafter, the present invention will be described in more detail.

The present invention is a substrate layer; And a structural layer formed on one side or both sides of the base layer and having a plurality of three-dimensional structures arranged thereon, wherein the three-dimensional structure of the structural layer has a longitudinal cross-section of which is slanted and extends in both directions based on one peak point. Wherein the inclined portion is symmetrical or asymmetrical with respect to the peak point, and each inclined portion is part of the circumference of the overlapping imaginary first ellipse and the second ellipse, wherein the first ellipse and the second ellipse are respectively represented by Equation 1 It relates to a light collecting optical sheet characterized in that the shape is defined by.

<Equation 1>

Wherein x and y are each real, a and b are integers 0 <a <b <10 and a: b is from 2: 1 to 100: 1. That is, the ellipse may be defined by the a and b values in the x-y coordinate system including the x and y axes.

The first ellipse and the second ellipse may have an elliptic shape as shown in FIG. 1 according to Equation 1.

The inclined portion may be formed by including one of the contacts formed by overlapping the first ellipse and the second ellipse as a peak point.

For example, as shown in FIG. 7, any one of the four contacts formed by overlapping the first ellipse and the second ellipse is a peak point, and any of the peak points and the circumference of the first ellipse and the second ellipse. Can be connected to form a slope.

In addition, the peak point, another contact point and peak point, and one of the circumferences of the first ellipse and the second ellipse, with one of four contacts formed by overlapping the first ellipse and the second ellipse as a peak point. Any one of them can be connected to form an inclined portion.

In addition, the inclined portion may be formed by connecting three of four contacts formed by overlapping the first ellipse and the second ellipse.

In the light converging optical sheet of the present invention, the three-dimensional structure 10 formed in the structural layer has an inclined longitudinal cross section extending in both directions with respect to one peak point 11, as shown in FIG. It includes a portion 12, the inclined portion 12 may be symmetrical or asymmetrical with respect to the peak point (11). When the inclined portion 12 is symmetrical, each of the first ellipse and the second ellipse including the respective inclined portions has the same shape, and in the asymmetrical case, the first ellipse and the second ellipse have different shapes. If it is.

As shown in FIG. 3, the inclined portion 12 of the three-dimensional structure is a part of the circumference of the superimposed virtual first ellipse 21 and the second ellipse 22, and the first ellipses 21 and the first ellipse 21 are formed. The two ellipses 22 can be defined by Equation 1.

<Equation 1>

Wherein x and y are each real, a and b are integers 0 <a <b <10 and a: b is from 2: 1 to 100: 1.

If a = b in Equation 1, it becomes a circle rather than an ellipse, and when a = ∞ or b = ∞, the inclined portion of the three-dimensional structure may be a straight line rather than a streamline.

On the other hand, since the inclined portion is streamlined and is part of the circumference of the first ellipse and the second ellipse, the curvature may be determined by the shape of the ellipse.

The shape of the first ellipse and the second ellipse may vary according to the a: b value of Equation 1, and a: b may be 2: 1 to 100: 1, and when a: b is less than 2: 1, the luminance is decreased. There is a severe problem, if more than 100: 1 there is a problem that the color uniformity according to the field of view does not improve. Preferably a: b is from 2: 1 to 8: 1.

Specifically, as shown in FIG. 3, the inclined portion 12 may include any three contacts A, B, and C among four contacts formed by overlapping the first ellipse 21 and the second ellipse 22. It may be a part of the first ellipse and the second ellipse adjacent to the hypotenuse (D) of the triangle formed by connecting the.

In this case, as illustrated in FIG. 4, the first ellipse 21 and the second ellipse 22 may overlap each of the long axes 23 at right angles, and the prism pattern when the long axes cross at 90 degrees or less. Becomes an acute prism and an obtuse prism above 90 degrees. It is advantageous that the prism pattern is formed such that the long axes 23 overlap each other at right angles, in terms of improving the luminance than when the prism patterns become acute or obtuse.

In addition, the center of the base of the three-dimensional structure and the center of the long axis of each of the first ellipse and the second ellipse may coincide.

On the other hand, the base layer may be formed of a resin selected from polyethylene terephthalate resin, polymethyl methacrylate resin, polycarbonate resin, polypropylene resin, polyethylene resin, polystyrene resin and styrene-acrylic copolymer resin.

In addition, the structural layer is a curable resin, and is not particularly limited as long as it is a light transmissive material. That is, any one selected from polymer resins including an ultraviolet curable resin or a thermosetting resin can be used without limitation, and examples thereof include unsaturated fatty acid esters, aromatic vinyl compounds, unsaturated fatty acids and derivatives thereof, and unsaturated dibasic acids. And derivatives thereof, and vinyl cyanide compounds such as methacrylonitrile. At this time, it is possible to adjust the polymer resin to be used in consideration of the refractive index with the base layer.

The base layer may have a thickness of 10 μm to 1000 μm, and preferably 15 μm to 400 μm in terms of preventing loss of transmitted light to be advantageous in mechanical strength, thermal stability, and flexibility.

On the other hand, although not shown, when the structural layer is formed on one side of the base layer, the bottom layer may be cured on the other side of the base layer, it may be used organic particles or inorganic particles as known light diffusing particles .

The present invention may provide a backlight unit assembly including the light collecting optical sheet described above, and the light collecting optical sheet may be formed on the uppermost layer to provide a backlight unit assembly which does not further include an additional protective sheet. .

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

Example 1

As a base material layer, the polyethylene terephthalate film T600 (Mitsubishi Corporation) (refractive index: 1.49) of 250 micrometers was used.

In order to design the three-dimensional structure of the structural layer, as shown in Figure 1 the longitudinal section of the three-dimensional structure is designed to include a slanted portion symmetrical around one peak point and the peak point.

At this time, the curvature of the slanted portion of the streamline is adjacent to the two hypotenuses of the triangle formed by connecting three contacts formed by making the long axes of the first ellipse and the second ellipse of the same shape and size orthogonal to each other perpendicular to each other. Part of the circumference of the first ellipse and the second ellipse. At this time, in formula 1, a: b was set to 6: 1.

The three-dimensional structure of the structural layer was arranged to be linear.

A mold having a three-dimensional structure designed as described above was produced, and a condensed optical sheet was produced by forming a structural layer (refractive index: 1.60) that was cured by injecting an acrylic ultraviolet curable resin composition (refractive index: 1.57).

The cross section of the obtained light converging optical sheet was observed using a scanning electron microscope (SEM), as shown in FIG. 5 (a).

Example 2

In Formula 1, the condensing optical sheet was produced in the same manner as in Example 1 except that a: b was 2: 1.

The cross section of the obtained light converging optical sheet was observed using a scanning electron microscope (SEM), as shown in FIG. 5 (b).

Example 3

In Formula 1, a condensing optical sheet was produced in the same manner as in Example 1 except that a: b was 4: 1 (not shown).

Example 4

In Formula 1, a condensing optical sheet was produced in the same manner as in Example 1 except that a: b was set to 8: 1 (not shown).

Comparative Example 1

A light converging optical sheet was manufactured in the same manner as in Example 1, except that the three-dimensional structure of the structural layer was an acute-angle prism having a triangular shape with an acute angle of 80 degrees.

The cross section of the obtained light converging optical sheet was observed using a scanning electron microscope (SEM), as shown in FIG. 5 (c).

Comparative Example 2

A light converging optical sheet was manufactured in the same manner as in Example 1, except that the three-dimensional structure of the structural layer was an obtuse prism having a triangular shape whose vertex angle of the cross section was an obtuse angle (100 degrees).

The cross section of the obtained light converging optical sheet was observed using a scanning electron microscope (SEM), as shown in FIG. 5 (d).

Comparative Example 3

In Formula 1, a condensing optical sheet was manufactured in the same manner as in Example 1 except that a: b was set to 1.5: 1.

The cross section of the obtained light converging optical sheet was observed using a scanning electron microscope (SEM), as shown in FIG.

Comparative Example 4

In Formula 1, a condensing optical sheet was manufactured in the same manner as in Example 1 except that a: b was set at 200: 1.

The cross section of the obtained light converging optical sheet was observed using a scanning electron microscope (SEM), as shown in FIG. 5 (f).

Comparative Example 5

In Formula 1, a condensing optical sheet was manufactured in the same manner as in Example 1 except that a: b was 1: 1.

That is, in a three-dimensional structure in which the longitudinal section is streamlined and includes an inclined portion symmetric about one peak point and the peak point, the streamline is not an ellipse but a part of a circular circumference.

For the light converging optical sheet manufactured in Examples and Comparative Examples, luminance and color uniformity were measured by the following method, and the results are shown in Table 1.

(1) luminance measurement

After sequentially stacking DBEF (Dual Brightness Enhancement Film), condensing optical sheet (Example or Comparative Example) and diffusion film on BLU (Backlight Unit, 27 inch LED 1vertical), brightness measuring equipment (BM-7A, TOPCON) 13 points were measured, and the average value was calculated.

The relative luminance value with respect to Ref. Was measured with the luminance of the prism film as the reference (Ref.). At this time, the prism formed on the prism film has a vertex angle of 90 degrees, a curvature R of 0, and a pitch of 50 mu m.

(2) color uniformity measurement

DBEF (Dual Brightness Enhancement Film), Condensing Optical Sheet (Example or Comparative Example) and Down Diffusion Film (KOLON, XC210) are sequentially stacked on BLU (27 inch LED 1vertical), and then color uniformity measuring equipment (SR3) , TOPCON), and after measuring the x and y color coordinates, it was converted to u 'and v' color coordinates using the following formula (2).

<Equation 2>

In Equation 2, in the XYZ color space coordinate system of CIE, the amount of three primary colors to be mixed to produce the same color as a given color is called X, Y, and Z (tristimulus values), and Y represents luminance.

X, Y, and Z may be represented by x and y using Equation 3 below.

<Equation 3>

The color can be obtained by applying the color coordinates (u ', v') obtained as described above to the CIE chromaticity diagram as shown in FIG.

On the other hand, the color uniformity was obtained by the following equation 4 using the color coordinates of the prism film as a reference (Ref.), And the color uniformity (Δu ′, Δv ′) is excellent as the negative value increases.

<Equation 4>

Color uniformity = (color coordinate of Ref.)-(Color coordinate of example or comparative example)

Table 1

	Luminance (%)	Color uniformity
		Horizontal		Vertical
		Δu	Δv	Δu	Δv
Ref.	100	Ref.	Ref.	Ref.	Ref.
Example 1	99	-0.0005	-0.0007	0	0
Example 2	97	-0.0006	-0.0029	0	-0.0008
Example 3	98	-0.0005	-0.0018	0	-0.0002
Example 4	99	-0.0004	-0.0003	0.0001	0
Comparative Example 1	90	-0.0004	-0.0008	0.0003	-0.001
Comparative Example 2	94	-0.0011	-0.0012	0.0012	0.0002
Comparative Example 3	95	0.0009	-0.0013	0.0017	-0.0011
Comparative Example 4	89	0.0001	-0.0022	0.0024	-0.0019
Comparative Example 5	93	-0.0005	-0.0028	0.0001	-0.0004

As a result of measuring the physical properties, as shown in Table 1, the light collecting type optical sheets of Examples 1 to 4 can be seen that the color uniformity is improved when the decrease in luminance is minimized.

However, Comparative Example 1 was excellent in color uniformity, but showed a severe decrease in luminance.

In addition, Comparative Examples 2 to 4 show that the vertical Δu 'value increases with brightness deterioration, and in particular, Comparative Example 3 shows that both Horizontal and Vertical Δu ′ increase.

Claims (8)

1. Base layer; And a structural layer formed on one or both surfaces of the base layer and having a plurality of three-dimensional structures arranged thereon.

   The three-dimensional structure of the structural layer is a streamlined longitudinal section, and includes a slope extending in both directions based on one peak point,

   The inclined portion is symmetrical or asymmetrical with respect to the peak point, and each inclined portion is part of the circumference of the imaginary first ellipse and the second ellipse,

   The first ellipse and the second ellipse are each condensing optical sheet, characterized in that the shape is defined by Equation 1.

   <Equation 1>

   

   Wherein x and y are each real, a and b are integers 0 <a <b <10 and a: b is from 2: 1 to 100: 1.
2. The method of claim 1,

   The inclined portion of the light converging optical sheet, characterized in that it comprises one of the contacts formed by overlapping the first ellipse and the second ellipse as a peak point.
3. The method of claim 1,

   The inclined portion is a light collecting type optical sheet, characterized in that the first ellipse and the second ellipse is a part of the first ellipse and the second ellipse adjacent to the hypotenuse of the triangle formed by connecting three of the contacts formed by overlapping.
4. The method of claim 3,

   The first ellipse and the second ellipse have their respective long axes perpendicular to each other, but the center of each long axis of the light converging optical sheet is characterized in that the overlap.
5. The method of claim 1,

   Condensing optical sheet, characterized in that the center of the center of the base of the three-dimensional structure and the center of the long axis of each of the first ellipse and the second ellipse is coincident with each other.
6. The method of claim 1,

   The substrate layer is a light converging optical sheet, characterized in that formed of a resin selected from polyethylene terephthalate resin, polymethyl methacrylate resin, polycarbonate resin, polypropylene resin, polyethylene resin, polystyrene resin and styrene-acrylic copolymer resin.
7. The method of claim 1,

   The structural layer is a light converging optical sheet, characterized in that formed of a resin selected from a polymer resin containing a UV curable resin or a thermosetting resin.
8. The backlight unit assembly comprising the light collecting optical sheet of any one of claims 1 to 7.

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