WO2013180385A1

WO2013180385A1 - Optical sheet and method for manufacturing same

Info

Publication number: WO2013180385A1
Application number: PCT/KR2013/003091
Authority: WO
Inventors: 김영길
Original assignee: 주식회사 코아옵틱스
Priority date: 2012-05-31
Filing date: 2013-04-12
Publication date: 2013-12-05
Also published as: KR101195309B1

Abstract

Suggested are an optical sheet of which the luminance can be enhanced and a method for manufacturing same. The optical sheet which is suggested comprises: a base material layer; and a Fresnel lens pattern layer including at least one Fresnel lens pattern which is provided on top of the base material layer.

Description

Optical sheet and its manufacturing method

The present invention relates to an optical sheet and a method for manufacturing the same, and more particularly, to an optical sheet capable of improving luminance and a method for manufacturing the same.

In the information display technology, the display device has occupied a position that CRT has been unique for more than half a century, but in the rapidly evolving information age, a larger and thinner display technology is required. As a result, flat panel display technology that can be enlarged and thinned has been developed. Liquid crystal display (LCD), projection display, and plasma display (PDP) have become mainstream, and field emission display (FED) and electroluminescent display ( ELD) has been developed along with the improvement of related technologies.

Compared with CRTs, LCDs are flat and large in size, and thus their use is expanding in display fields such as monitors and TVs, accounting for 80% of the flat panel market. The LCD includes a panel in which a liquid crystal and an electrode matrix are disposed between a pair of light absorbing optical films. In an LCD, the liquid crystal portion moves the liquid crystal portion by an electric field generated by applying a voltage to two electrodes, thereby having an optical state that is changed, and displaying an image using a polarized light in a specific direction. . Thus, the LCD includes a front optical film and a back optical film that induce polarization.

Since the LCD is not a self-luminous display but a non-luminous display, it includes a backlight unit on the back and uses the light generated therefrom. The backlight unit used in such a non-light emitting display includes an edge type backlight unit that supplies light from a side of the display panel and a direct backlight unit that directly supplies light from a rear side of the display panel. In the case of an edge type backlight unit, a light guide plate is provided to radiate light emitted from a light source upwardly, and at least one optical sheet, for example, a diffusion sheet, is disposed above the light guide plate to adjust optical characteristics of light passing through the light guide plate. Or a prism sheet.

With the trend toward larger and thinner flat panel displays, efforts have been made to secure a predetermined amount of light and luminance supplied to the display panel while maintaining or minimizing the number of light sources. Accordingly, an optical sheet has been added to improve the amount of light and the brightness of the backlight unit, but this has caused a problem that is contrary to the trend of thinning of the display.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical sheet capable of improving luminance and a manufacturing method thereof.

Optical sheet according to an aspect of the present invention for achieving the above object, the base layer; And a Fresnel lens pattern layer including at least one Fresnel lens pattern on the base layer. The Fresnel lens pattern may be embossed, or the Fresnel lens pattern may be engraved. In addition, the Fresnel lens pattern may be in the form of a bar.

The Fresnel lens pattern layer may have an inclination in the longitudinal direction with respect to the base material layer, or the Fresnel lens pattern layer may have an inclination in the Fresnel lens pattern cross-sectional direction with respect to the base material layer. Furthermore, the Fresnel lens pattern layer may have both the inclination in the longitudinal direction and the inclination in the cross section of the Fresnel lens pattern with respect to the substrate layer.

The optical sheet according to the embodiment of the present invention may include two or more Fresnel lens patterns, and when the Fresnel lens pattern is the first Fresnel lens pattern and the second Fresnel lens pattern, the first Fresnel The lens pattern may have a positive first slope and the second Fresnel lens pattern may have a negative second slope. In this case, the first Fresnel lens pattern and the second Fresnel lens pattern may be adjacent to each other. In addition, the Fresnel lens pattern layer may include a plurality of pairs of the first Fresnel lens pattern and the second Fresnel lens pattern.

The angle of inclination of the Fresnel lens pattern layer with respect to the substrate layer may be 0.7 ° to 1.5 °.

It is preferable that a Fresnel lens pattern layer is located in front of a base material layer, and it is preferable that a Fresnel lens pattern layer is integral with a base material layer.

According to another aspect of the present invention, by applying a master roll including a Fresnel lens pattern to the base layer to form a Fresnel lens pattern layer on the base layer; there is provided an optical sheet manufacturing method comprising a. When the master roll is applied on the substrate layer, the substrate layer is preferably moved.

According to another aspect of the invention, the light guide plate; A light source positioned on at least one of side and bottom surfaces of the light guide plate; And an optical sheet including a Fresnel lens pattern layer on an upper surface of the light guide plate. The Fresnel lens pattern may be positioned to face the light guide plate, or the Fresnel lens pattern may be positioned toward an exit surface from which light is emitted from the backlight unit.

The backlight unit including the optical sheet according to the present invention is capable of uniform backlighting by reducing hot spots, improving luminance, and the optical sheet can be used as a polarizing film, so that the minimum number of optical sheets can be used. It works.

In addition, since the pattern layer has a bar shape, it is easy to manufacture and is formed on the entire surface, so that the light collecting efficiency is increased.

In addition, since the Fresnel lens pattern layer is positioned with an inclination with respect to the base layer, the light condensing direction can be adjusted, so that light condensing can be adjusted in a desired direction according to the arrangement of the light source, thereby effectively disposing the light source.

Furthermore, in the case of providing two kinds of Fresnel lens patterns, it is possible to apply the autostereoscopic 3D display without additional devices or components by adjusting the condensing direction.

1 is a cross-sectional view of a backlight unit according to an embodiment of the present invention, FIG. 2 is a perspective view of the backlight unit of FIG. 1, and FIGS. 3 and 4 are cross-sectional views of a backlight unit according to another embodiment of the present invention.

5 is a perspective view of an inclined optical sheet in a longitudinal direction according to another embodiment of the present invention, and FIG. 6 is a cross-sectional view of an inclined optical sheet in a cross-sectional direction of a Fresnel lens pattern according to another embodiment of the present invention. .

FIG. 7 is a cross-sectional view of an optical sheet including Fresnel lens patterns having different inclinations, and FIG. 8 is a view illustrating a condensing form of the optical sheet of FIG. 7.

9 is a view provided for explaining the manufacturing method of the optical sheet according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. In the accompanying drawings, there may be a component having a specific pattern or having a predetermined thickness, but this is for convenience of description or distinction. It is not limited only.

1 is a cross-sectional view of a backlight unit according to an embodiment of the present invention, Figure 2 is a perspective view of the backlight unit of FIG.

The backlight unit 100 according to the present embodiment includes a light guide plate 130; And an optical sheet 110 including a light source 120 positioned on at least one of a side surface and a lower surface of the light guide plate and a Fresnel lens pattern layer 112 positioned on an upper surface of the light guide plate 130. Here, the optical sheet 110 is a base layer 111; And a Fresnel lens pattern layer 112 on the base layer 111.

The light source 120 is for supplying light from the back of the display device. For example, a light source such as a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) may be used. .

The light source 120 is positioned on at least one of side and bottom surfaces of the light guide plate 130. In FIG. 1 and FIG. 2, the edge type backlight unit in which the light source 120 is positioned on one side of the light guide plate 130 is illustrated. In contrast, the present invention is also applicable to a direct type backlight unit positioned on the bottom surface of the light guide plate 130. It is obvious to those skilled in the art to which the present invention pertains.

The light guide plate 130 is made of a resin made of a transparent material such as polymethyl methacrylate (PMMA), and guides light from the light source 120 to the emission surface to uniformly transmit light to the entire surface of the display device. A reflecting plate (not shown) may be provided on the opposite side of the emitting surface of the light guide plate 130 to reflect the light traveling toward the opposite surface side of the emitting surface back to the emitting surface side, and the upper surface of the light guide plate 130 may be provided on the light emitting plate 130. A diffusion plate (not shown) for uniformly diffusing the light traveling from 130 may be provided.

The optical sheet 110 is positioned on the upper surface of the light guide plate 130. As shown in FIG. 1, the optical sheet 110 may be in contact with the light guide plate 130 or may be spaced apart from a predetermined distance. The optical sheet 110 includes a Fresnel lens pattern layer 112, and is positioned on the base layer 111 that can support the Fresnel lens pattern layer 112 as shown in FIG. 1.

The base layer 111 is a substrate on which the Fresnel lens pattern layer 112 is located, and includes glass, polycarbonate, polyallylate, polyethersulfone, amorphous polyolefin or polyethylene terephthalate, polymethyl methacrylate, and the like. It may include a transparent material (transparent material).

Fresnel lens pattern layer 112 may be formed by molding a light-transmissive resin, for example, acrylic resin, such as polymethyl methacrylate, polyhydroxyethyl methacrylate or polycyclohexyl methacrylate, poly Allyl resin, such as diethylene glycol bisallylcarbonate or polycarbonate, methacryl resin, polyurethane resin, polyester resin, polyvinyl chloride resin, polyvinyl acetate resin, cellulose resin, polyamide resin, fluorine resin At least one of resin, polypropylene resin and polystyrene resin may be used. Alternatively, the base layer 111 and the Fresnel lens pattern layer 112 may be integrally formed by using one kind of resin.

The Fresnel lens pattern layer 112 is a layer on which a pattern of the Fresnel lens is formed. Fresnel lens is generally a lens that serves as a convex lens by dividing into a plurality of circular band-shaped lens in order to reduce the thickness of the convex lens. Fresnel lenses can be used to create large-diameter lenses without increasing the thickness of the lens. When the Fresnel lens pattern is incident on one surface of the Fresnel lens, the Fresnel lens pattern is focused on the other surface irrespective of the incident angle of the incident light to emit light. Therefore, when the light source 120 is located at the side or the rear side of the light guide plate 130, the light source 120 may focus light upward through the Fresnel lens pattern layer 112 to emit light.

Therefore, since the light from the light source 120 is focused upward through the Fresnel lens pattern layer 112, the luminance is improved, and the hot spot is reduced, thereby enabling uniform backlighting. In addition, by adjusting the shape of the Fresnel lens pattern of the Fresnel lens pattern layer 112 to form a Brewster angle (Brewster angle), it can also be used as a polarizing film to reduce the number of optical sheet backlight unit and this The display can be thinned.

Referring to FIG. 2, the Fresnel lens pattern layer 112 includes a Fresnel lens pattern having a bar shape. That is, in the present embodiment, the Fresnel lens pattern is formed in the shape of a bar formed along one surface of the light guide plate 130. Since the Fresnel lens pattern has a bar shape, the Fresnel lens pattern may be formed over the entire surface of the light guide plate 130, and the entire incident light from the light source 120 may be focused to improve luminance efficiency, resulting in more uniform light condensation. Reduces hot spots In addition, one Fresnel lens pattern may be corresponded to one light source, thereby making it possible to efficiently collect incident light from each light source.

3 and 4 are cross-sectional views of a backlight unit according to another embodiment of the present invention. In the backlight unit 100 ′ of FIG. 3, the Fresnel lens pattern of the Fresnel lens pattern layer 112 ′ on the base layer 111 ′ is intaglio. In FIG. 1, an embossed Fresnel lens pattern may be formed in the Fresnel lens pattern layer 112, while an intaglio Fresnel lens pattern may be implemented as shown in FIG. 3. In the case of embossing the Fresnel lens pattern, the angle of each pattern of the Fresnel lens pattern is variously adjusted to control the light condensing direction in consideration of the position of the light source 120 'or the thickness or characteristics of the light guide plate 130'. Even easier.

In the backlight unit 100 ″ of FIG. 4, unlike the optical sheet 110 of FIG. 1, a Fresnel lens pattern layer 112 ″ is disposed under the base layer 111 ″. That is, the Fresnel lens pattern layer 112 of FIG. 1 is positioned toward the exit surface from which light is emitted from the backlight unit 100, whereas the Fresnel lens pattern layer 112 ″ of FIG. 4 is a light guide plate 130 ″. )

As shown in FIG. 4, when the Fresnel lens pattern layer 112 ″ is positioned to face the light guide plate 130 ″, light may be efficiently collected from a point light source such as the light source 120 ″. Particularly, in the case of the direct type backlight unit in which the light source is located on the lower surface of the light guide plate, the Fresnel lens pattern layer 112 ″ efficiently converts the light from the light source in the vertical direction to the exit surface side to prevent hot spots, thereby improving luminance. Can be improved.

5 is a perspective view of an inclined optical sheet in a longitudinal direction according to another embodiment of the present invention, and FIG. 6 is a cross-sectional view of an inclined optical sheet in a cross-sectional direction of a Fresnel lens pattern according to another embodiment of the present invention. . In FIG. 2, the direction in which the Fresnel lens pattern of the Fresnel lens pattern layer 112 is formed to be long is called the Fresnel lens pattern longitudinal direction A, and the cross-sectional direction of the Fresnel lens pattern is the Fresnel lens pattern cross-sectional direction B It is called). Hereinafter, a description will be given with reference to FIGS. 2, 5, and 6.

In FIG. 5, the optical sheet 210 has an inclination angle θ _{1 in} the Fresnel lens pattern longitudinal direction A, and in FIG. 6, the optical sheet 310 has an inclination angle θ _{2 in the} Fresnel lens pattern cross-section direction B. Has a slope.

That is, in FIG. 5, the Fresnel lens pattern layer 212 has an inclination extending in the longitudinal direction, that is, the bar shape, on the base layer 211. Referring to FIG. 2, the Fresnel lens pattern layer 212 has a height higher on the opposite side where the light source is not positioned than on the light guide plate. In contrast, in FIG. 6, the Fresnel lens pattern layer 312 is formed on the base layer 311 at one side of the cross section of the Fresnel lens pattern in contact with the base layer 311, and the other side is formed at a predetermined height from the base layer 311. The cross section of the Fresnel lens pattern is formed in an inclined form.

When the inclination is formed as shown in FIG. 5, the condensed light is emitted in a form inclined toward the light source and condensed in a desired direction. In addition, when the light source is located on one side of the backlight unit as shown in FIG. 2, light incident on the light guide plate from the light source is emitted after moving away from the incident surface. When the light travels a long distance from the light guide plate, the amount of light is lost, and the light having a longer travel distance can be collected more efficiently in a Fresnel lens pattern having an inclination as shown in FIG. 5.

When the inclination is formed as shown in FIG. 6, the collected light is inclined in the left direction in the drawing and is emitted. On the contrary, if the Fresnel lens pattern layer having the inclination in the opposite direction to FIG. 6 is formed, it will be inclined to the right in the drawing and thus the outgoing can be made in the desired direction by adjusting the inclination. In addition, the inclination of the Fresnel lens pattern layer can be formed to have both the inclination of the Fresnel lens pattern longitudinal direction (A) and the Fresnel lens pattern cross-sectional direction (B), so that a single Fresnel lens pattern is used for two-dimensional Condensing direction can be adjusted.

In FIG. 2, the light source 120 is positioned at one side of the light guide plate 130, but differently, the light source is located at at least one of the edges of the light guide plate, or is located at a greater number than the other side on one side or is not symmetric with each other. There may be cases. In this case, since the inclination of the Fresnel lens pattern of the Fresnel lens pattern layer can be adjusted at various angles to condense in a desired direction, the light source can be efficiently arranged.

The inclination of the Fresnel lens pattern layer may be selected according to the desired condensing direction. In particular, the inclination of the Fresnel lens pattern layer with respect to the substrate layer may be 0.7 ° to 1.5 °.

FIG. 7 is a cross-sectional view of an optical sheet including Fresnel lens patterns having different inclinations, and FIG. 8 is a view illustrating a condensing form of the optical sheet of FIG. 7. In the present invention, the optical sheet may include two or more Fresnel lens patterns. In FIG. 7, the optical sheet 410 includes two kinds of

Fresnel lens patterns

412 and 413 having different inclinations with respect to the base layer 411.

The first Fresnel lens pattern 412 and the second Fresnel lens pattern 413 respectively have an inclination in the cross section of the Fresnel lens pattern with respect to the base layer 411. The first Fresnel lens pattern 412 has a first slope, and the second Fresnel lens pattern 413 has a second slope. In addition, the first Fresnel lens pattern 412 has a first inclination of a positive value, and the second Fresnel lens pattern 413 has a second inclination of a negative value. That is, when θ ₃ , which is the first inclination degree in FIG. 7, is a positive value, θ _{4, which} is the second inclination degree of the second Fresnel lens pattern 413 facing this, is a negative value.

Accordingly, as shown in FIG. 8, the first Fresnel lens pattern 412 is focused in the right direction as shown in the drawing, and the second Fresnel lens pattern 413 is focused in the left direction as shown in the drawing. Using 410, the light can be focused in two directions.

In this case, as shown in FIG. 7, the first Fresnel lens pattern 412 and the second Fresnel lens pattern 413 are located adjacent to each other, and the first Fresnel lens pattern 412 and the second Fresnel lens pattern are located. In the case of the optical sheet 410 including a plurality of pairs, the light collecting direction may be adjusted and applied to the autostereoscopic 3D display. That is, the light L ₂ from the first Fresnel lens pattern 412 is seen from the second Fresnel lens pattern 413 to the right eye of the user to be located to the left as seen in the drawing. Since light L ₁ reaches, it can be applied to auto glasses-free 3D display without any extra parts.

9 is a view provided for the description of the manufacturing method of the optical sheet according to the embodiment of the present invention. In the present embodiment, the optical sheet including the Fresnel lens pattern layer is manufactured by applying the master roll 520 including the Fresnel lens pattern 522 to the base layer 511.

9, a master roll 520 having a master roll Fresnel lens pattern 522 having a shape opposite to a desired Fresnel lens pattern is formed on the base layer 511 moving in the direction of the arrow. The NEL lens pattern 512 is formed integrally with the base layer 511.

In particular, when the Fresnel lens pattern layer is bar-shaped as shown in Figure 9, using the master roll 520 it is possible to manufacture the optical sheet in a simpler process, and the Fresnel lens pattern layer on the front surface of the substrate layer 1 Since it can be formed by applying it once, it is possible to manufacture the optical sheet with a minimum of the master roll can be used to extend the life of the expensive master roll to the maximum.

In FIG. 9, the optical sheet of the present invention is directly manufactured by using a master roll. Alternatively, a pattern such as a polyethylene terephthalate film or a polycarbonate film is formed by using a master roll having the same pattern as a desired Fresnel lens pattern. It is apparent to those skilled in the art that a method of forming a Fresnel lens pattern on a base layer using a duplicated film and using a duplicated film may be used.

The invention is not to be limited by the foregoing embodiments and the accompanying drawings, but should be construed by the appended claims. In addition, it will be apparent to those skilled in the art that various forms of substitution, modification, and alteration are possible within the scope of the present invention without departing from the technical spirit of the present invention.

Claims

Base layer; And

And a Fresnel lens pattern layer including at least one Fresnel lens pattern on the base layer.
The method according to claim 1,

The Fresnel lens pattern is an optical sheet, characterized in that the embossed form.
The method according to claim 1,

The Fresnel lens pattern is an optical sheet, characterized in that the intaglio form.
The method according to claim 1,

The Fresnel lens pattern is an optical sheet, characterized in that the bar (bar) shape.
The method according to claim 1,

The Fresnel lens pattern has an inclined in the longitudinal direction with respect to the base layer.
The method according to claim 1,

And the Fresnel lens pattern has an inclination in a cross section direction of the Fresnel lens pattern with respect to the base layer.
The method according to claim 1,

The Fresnel lens pattern layer has an inclination in the longitudinal direction and the Fresnel lens pattern cross-sectional direction with respect to the substrate layer.
The method according to claim 6,

Includes two or more Fresnel lens patterns,

The two or more Fresnel lens patterns are a first Fresnel lens pattern and a second Fresnel lens pattern,

The first Fresnel lens pattern has a positive first inclination, and the second Fresnel lens pattern has a negative second inclination.
The method according to claim 8,

And the first Fresnel lens pattern and the second Fresnel lens pattern are adjacent to each other.
The method according to claim 9,

And the Fresnel lens pattern layer includes a plurality of pairs of the first Fresnel lens pattern and the second Fresnel lens pattern.
The method according to any one of claims 5 to 7,

The angle of the inclination is an optical sheet, characterized in that 0.7 ° to 1.5 °.
The method according to claim 1,

The Fresnel lens pattern layer is an optical sheet, characterized in that located on the front of the base layer.
The method according to claim 1,

The Fresnel lens pattern layer is an optical sheet, characterized in that integral with the base layer.
And applying a master roll including a Fresnel lens pattern to the base layer to form a Fresnel lens pattern layer on the base layer.
The method according to claim 14,

When the master roll is applied, the substrate layer is characterized in that the movement of the optical sheet manufacturing method.
Light guide plate;

A light source positioned on at least one of side and bottom surfaces of the light guide plate; And

And an optical sheet including a Fresnel lens pattern layer including at least one Fresnel lens pattern positioned on an upper surface of the light guide plate.
The method according to claim 16,

The Fresnel lens pattern is positioned to face the light guide plate.
The method according to claim 16,

And the Fresnel lens pattern is positioned toward the emission surface of the light from the light source.