KR100802999B1 - Optical sheet and back light assembly of luquid crystal display equipped with the prism sheet - Google Patents

Abstract

The present invention relates to an optical sheet, and more particularly, to an optical sheet having a predetermined protrusion and a backlight assembly of a liquid crystal display device having the optical sheet.

Optical sheet according to the present invention is a light incident light, the projecting portion is formed to project a predetermined thickness; And a body part formed on an upper side of the protruding part, wherein the protruding part comprises a first protruding part having a predetermined curvature and a second protruding part formed in a prism shape.

Optical sheet

Description

Optical sheet and back light assembly of luquid crystal display equipped with the prism sheet

1 and 2 are views for explaining a backlight assembly of a conventional direct type liquid crystal display device.

3 and 4 show the movement of light in a conventional backlight assembly.

5A is a cross-sectional view illustrating an optical sheet according to a first embodiment of the present invention.

5B is a perspective view for explaining an optical sheet according to a first embodiment of the present invention.

6 is a view for explaining how light is moved in the optical sheet according to the first embodiment of the present invention.

7 is a cross-sectional view illustrating an optical sheet according to a second embodiment of the present invention.

8A is a cross-sectional view for illustrating an optical sheet according to a third embodiment of the present invention.

8B is a perspective view for explaining an optical sheet according to a third embodiment of the present invention.

9 is a view for explaining a state in which light is moved in the optical sheet according to the third embodiment of the present invention.

10 is a photograph showing a luminance distribution in a backlight assembly according to the prior art.

11 is a photograph showing luminance distribution in a backlight assembly using an optical sheet according to the present invention.

The present invention relates to an optical sheet, and more particularly, to an optical sheet having a predetermined protrusion and a backlight assembly of a liquid crystal display device having the optical sheet.

The liquid crystal display device includes a liquid crystal display panel, which includes a TFT array substrate in which unit pixels are arranged and thin film transistors are arranged as switching elements for each unit pixel, and the TFT array substrate faces and expresses colors. A color filter substrate, and a liquid crystal layer filled between the two substrates.

Since the liquid crystal display panel does not emit light by itself, light must be supplied from the outside in order to express an image.

In addition, the LCD may be classified into an edge type and a direct type according to a structure in which a backlight, which is a light source, is installed. The edge type has a backlight assembly formed on the side of the liquid crystal display panel, and the direct type has a backlight assembly formed under the liquid crystal display panel.

Edge type liquid crystal display devices are used for small liquid crystal display devices, and direct type liquid crystal display devices are mainly used for large liquid crystal display devices.

1 and 2 illustrate a backlight assembly of a conventional direct type liquid crystal display.

In the backlight assembly, as a light source, a plurality of bar lamps 103 are formed under the liquid crystal display panel (not shown) in parallel with each other, and are protected by a lower cover 101 which is a mold frame. The upper surface of the lower cover 101 is provided with a reflecting plate 102 for reflecting the light of the lamp 103 to the liquid crystal panel, a plurality of lamps 103 are arranged on the reflecting plate 102. Further, a diffusion plate 104 for uniformly diffusing the light generated from the lamp 103 into the liquid crystal panel, a diffusion sheet 105 placed on the diffusion plate 104, and the diffusion sheet 105. A prism sheet 106 is further provided for refracting the light diffused by.

In addition, although not shown, in general, a protective sheet (not shown) is further provided on the prism sheet 106, and thus, a cost of the product is increased as a plurality of films or sheets are used in the direct backlight assembly in the related art. Will rise.

The diffusion plate 104 and the diffusion sheet 105 are supported by the edge of the lower cover.

A plurality of lamps 103, which are light sources, are formed on the reflecting plate 102 in parallel with each other, and the lamps 103 are supported by the lamp fixing members 111.

Electrodes for supplying power to the lamp are formed at both ends of the lamp 103, the lamp electrode is supported by the lamp support 112 formed on both sides of the lower substrate (101). In addition, an electrode supply line (not shown) for supplying power to the lamp is connected to both electrodes of the lamp 103.

The power supply lines are connected to each other to form a closed circuit around a single lamp. In the closed circuit, an inverter that converts a DC voltage applied from the outside into an AC voltage and supplies a current to the lamp is installed.

In general, a cold cathode fluorescent lamp (CCFL) is used as the lamp. Looking at the structure of the lamp, the lamp includes a light emitting part coated with a fluorescent material and an external device for applying a voltage to the lamp. It can be divided into electrode parts.

Meanwhile, a problem occurring in the conventional direct type backlight assembly will be described with reference to FIG. 3.

3 and 4 are diagrams showing the movement of light in a conventional backlight assembly.

Referring to FIG. 3, as a lamp is used as a light source, which is generally circular in cross section, the light emitted from the lamp is not evenly incident on all regions of the diffusion plate.

That is, as shown, the reflecting plate portion 3A positioned above the light source has a high density of incident light, but the reflecting plate portion 3B positioned in the region between the light source and the light source has a relatively low density of incident light.

In addition, in the conventional direct backlight assembly, many efforts have been made to reduce the number of plates or sheets used, and among them, the diffusion sheet 105 together with the diffusion plate 104. Sometimes only three are used.

However, in this case, too, as the three diffusion sheets are laminated in addition to the diffusion plate 104, the manufacturing cost thereof increases, and there is a limit in improving the optical characteristics.

In addition, the incident angle of the incident light is often greater than the magnitude of the critical angle totally reflected in the portion 3B of the reflecting plate formed at the position of the region between the lamp and the lamp, and is reflected on the surface of the reflecting plate, and the reflected light is moved toward the lamp side. As a result, there is a problem of lowering the optical efficiency of the backlight assembly.

In addition, since the density of light incident on the portion of the reflector located in the area between the lamp and the lamp is low, the luminance of the light emitted through the liquid crystal display becomes uneven and the image is not clearly displayed through the liquid crystal display. There is this.

The present invention is proposed to solve the above problems, the light generated from the light source to be evenly moved to the side of the liquid crystal display panel, an optical sheet capable of improving the optical characteristics of the backlight assembly and the liquid crystal display with the optical sheet It is an object to propose a backlight assembly of the device.

Another object of the present invention is to propose an optical sheet and a backlight assembly of a liquid crystal display device having the optical sheet, which can replace the conventional diffusion plate and at the same time reduce the number of diffusion sheets.

An optical sheet according to an embodiment of the present invention for achieving the above object is an optical sheet for moving the light moved from the light source toward the liquid crystal display panel side, the optical sheet has a protrusion protruding toward the light source, The protrusion may be formed in a different shape according to the position of the light source.

In addition, the optical sheet according to the present invention includes a protrusion in which light is incident and protrudes a predetermined thickness; And a body part formed on an upper side of the protruding part, wherein the protruding part comprises a first protruding part having a predetermined curvature and a second protruding part formed in a prism shape.

In addition, the optical sheet according to the present invention includes a body portion forming a substrate; And a protrusion having a predetermined thickness protruding from the surface of the body portion, wherein the protrusion includes a first protrusion that serves to diffuse incident light and a second protrusion that condenses incident light. The cross-sectional shape of the first protrusion and the second protrusion is different.

In addition, the optical sheet according to the present invention includes a body portion, and protrusions protruding a predetermined thickness from the surface of the body portion, wherein the protrusions are embossed first protrusions, the first protrusions and the shape is reversed It is characterized by consisting of a second projection of the intaglio shape.

The backlight assembly of the liquid crystal display according to the present invention comprises a lamp for generating light; A reflection plate installed under the lamp and reflecting light generated from the lamp; And an optical sheet provided on the upper side of the reflecting plate and configured to guide incident light toward the liquid crystal display panel, wherein the optical sheet is provided with a protrusion having a predetermined thickness protruding toward the reflecting plate.

In addition, the backlight assembly of the liquid crystal display according to the present invention includes a lamp for generating light; A reflection plate installed under the lamp and reflecting light generated from the lamp; And an optical sheet provided on the upper side of the reflecting plate and configured to guide incident light toward the liquid crystal display panel, wherein the optical sheet is provided with a protrusion for diffusing or condensing the light generated from the lamp. Is characterized in that it is formed to have a predetermined bend.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention will be described in detail. However, the spirit of the present invention is not limited to the embodiments in which the present invention is presented, and those skilled in the art who understand the spirit of the present invention easily suggest other embodiments by adding, changing, adding, and deleting elements within the scope of the same idea. Although this may be done, this also falls within the scope of the spirit of the present invention.

5A is a cross-sectional view illustrating an optical sheet according to a first embodiment of the present invention, and FIG. 5B is a perspective view illustrating an optical sheet according to a first embodiment of the present invention.

In addition, the optical sheet according to the present invention may be used in place of a conventional diffusion plate, and furthermore, in view of its role, a conventional diffusion plate and a diffusion sheet are combined.

5A and 5B, the optical sheet 200 according to the first embodiment of the present invention includes a body 210 and a protrusion 220 protruding a predetermined height from the body 210. The protrusion 220 includes a first protrusion 221 having a relatively smooth curve, and a second protrusion 222 having a shape that can be identified from the first protrusion 221.

The protrusion 220 serves to condense or diffuse incident light, and the protrusion 220 refracts and diffuses the light generated from the light source 203 so that the luminance of the light is evenly distributed. Be sure to

In addition, although only the optical sheet according to the present invention is illustrated in the drawings, the diffusion sheet may be further used in the backlight assembly to which the optical sheet of the present invention is applied.

In detail, the body portion 210 is formed of a flat surface and the surface formed with the protrusion 220, the protrusion 220 is coated on the body portion 210.

In this case, the body portion 210 made of acryl is characterized in that the protrusions 220 of various shapes according to the present invention are formed.

In addition, the protrusion 220 may be manufactured by using a molding mold patterned in a reverse phase with the protruding shape of the protrusion 220 by a roll-coating method.

The protrusion 220 includes a first protrusion 221 having a predetermined curvature and a second protrusion 222 having a prism shape, and the first protrusion 221 is positioned at a vertical position from the light source 203. Is formed.

In more detail, the first protrusion 221 serves to diffuse the light generated from the light source 203, and the second protrusion 222 serves to condense the light generated from the light source 203. To perform.

In addition, the first protrusion 221 may have a predetermined curvature, the cross-sectional shape of which may be part of a circle or an ellipse, and may be regarded as a convex lens.

The second protrusion 222 has a prism shape or a triangular cross section, and is linearly arranged in the longitudinal direction of the diffusion sheet 200. The second protrusion 222 has a predetermined inclined surface, and the end portion of the second protrusion 222 has a pointed shape as the inclined surface is formed.

5A and 5B, although the first protrusion 221 and the second protrusion 222 are shown to be arranged regularly (or linearly) with a predetermined number, respectively, the light sources 203 More first protrusions 221 may be formed or more second protrusions 222 may be formed depending on the distance therebetween.

The light source 203 is positioned below the first protrusion 221 so that the second protrusion 222 is positioned vertically above the region between the light source 203 and the light source.

In this case, the second protrusion 222 is formed at a position where the density of the light incident from the light source 203 is relatively small, thereby inducing the light passing through the second protrusion 222 to be collected and to the first light. The light passing through the protrusion 221 is diffused to induce light to move toward the second protrusion 222.

Therefore, even when there is a region where the amount of incident light is relatively small according to the position of the light source 203, the light eventually passing through the optical sheet 200 toward the liquid crystal display panel may be uniformly distributed in all regions. Can be.

The optical sheet 200 according to another aspect of the present invention serves to move the light moved from the light source toward the liquid crystal display panel, and the optical sheet 200 protrudes toward the light source 203. 220, the protrusion 220 has a different shape according to the position of the light source 203.

In this case, the protrusion 220 has a predetermined inclined surface, and the protrusion located vertically upward of the light source 203 is urgently formed, and is located vertically upward in an area between the light sources 203. The protrusion is formed with a gentle slope.

Meanwhile, the body portion 210 may include, but is not limited to, a polyethylene film made of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), oriented polypropylene, polycarbonate, triacetate, and the like.

For example, polyester films such as Tetron® film, MELINEX® film and the like can be used as the substrate.

In addition, the protrusion 220 may be formed of a UV curable acrylate or a thermosetting resin and coated on the surface of the body portion 210.

6 is a view for explaining a state in which light is moved in the optical sheet according to the first embodiment of the present invention.

As described above, the first protrusion 221 is positioned vertically above the light source 203, and the second protrusion 222 is positioned vertically above the regions between the light sources.

Accordingly, the light 6A incident on the first protrusion 221 is refracted and diffused by the gentle surface of the first protrusion 221 and the light 6B incident on the second protrusion 222. They are refracted and collected by a prism shape of the second protrusion 222.

According to the exemplary embodiment of the present invention, the first projection may include an area in which light generated from the light source 203 is incident relatively less and an area in which light is relatively incident to the optical sheet. The convex portion 221 is formed to be convex, and a region where light is relatively incident is formed to have a triangular shape like the second protrusion 222.

7 is a cross-sectional view for describing an optical sheet according to a second exemplary embodiment of the present invention.

Referring to FIG. 7, the optical sheet 300 according to the present invention includes a body 310 facing the liquid crystal display panel and a protrusion 320 protruding a predetermined thickness on the surface of the body 310. The protrusion 320 is coated on the surface of the body 310.

In detail, the protrusion 320 includes an embossed third protrusion 321 and an intaglio fourth protrusion 322, and the embossed third protrusion 321 is vertically upward of the light source 303. It is formed to be located in.

In addition, the fourth protrusion 322 having an intaglio shape is formed to be positioned vertically upward in an area of the space between the light sources 303.

The third protrusion 321 serves to diffuse light incident like the first protrusion 221 described above, and the fourth protrusion 322 is incident like the second protrusion 222 described above. It serves to condense light.

Therefore, in the region where the amount of incident light is relatively small, light collected by the fourth protrusion 322 and light diffused and guided by the third protrusion 321 are present. The generated light is moved while having an even luminance distribution in the entire area of the diffusion sheet 300.

8A is a cross-sectional view illustrating an optical sheet according to a third embodiment of the present invention, FIG. 8B is a perspective view illustrating an optical sheet according to a third embodiment of the present invention, and FIG. 9 is a third view of the present invention. FIG. Is a view for explaining how light is moved in the optical sheet according to the embodiment.

First, referring to FIGS. 8A and 8B, the optical sheet 400 according to the third embodiment of the present invention includes a body portion 410 and an upper protrusion portion protruding from the surface of the body portion 410 toward the liquid crystal display panel. 430 and a lower protrusion 420 protruding from the surface of the body portion 410 toward the light source 403.

8A to 9, the lower protrusion 420 is illustrated in the shape of the protrusion according to the first embodiment of the present invention described above, but may be provided in the shape of the protrusion according to the second embodiment of the present invention.

In addition, the upper protrusion 430 is provided in a convex shape having a predetermined curvature, and the cross section is a shape of a circle or an ellipse as shown.

In addition, although the upper protrusion 430 is illustrated as having a plurality of regular convex shapes having a predetermined curvature, irregularly convex shapes may be formed.

That is, the upper protrusion 430 is provided in a shape protruding a predetermined thickness on one surface of the body portion 410, the upper protrusion 430 is formed in a shape that increases in thickness toward the center from the edge.

In more detail, as the upper protrusion 430 is formed to protrude to a predetermined thickness, the body portion 410 may be described as having a plurality of convex lenses, and the body portion 410 The face can also be seen as an embossing face.

In addition, a plurality of upper protrusions 430 may be irregularly provided, and may be formed to be spaced apart from each other by a predetermined distance between the upper protrusions 430.

In addition, the lower protrusion 420 includes a fifth protrusion 421 formed so that its cross section has a predetermined radius of curvature, and a sixth protrusion 422 provided in a triangular shape or a prism shape. The protrusion 421 serves to diffuse the incident light, and the sixth protrusion 422 collects the incident light.

An optical sheet according to a third embodiment of the present invention according to another aspect is represented as follows.

That is, the optical sheet 400 according to the third embodiment of the present invention includes a lower protrusion 420 protruding in a direction toward the light source 403, and a body portion through which light passing through the lower protrusion 420 flows ( 410 and the upper protrusion 430 to emit light passing through the body 410 to the upper side, the upper protrusion 430 has a shape that becomes thicker toward the center from its edge. .

As described above, the upper protrusion 430 is irregularly arranged in plural on the surface of the body 410.

The lower protrusion 420 is alternately formed while the fifth protrusion 421 having a predetermined curvature and the sixth protrusion 422 having a triangular cross section repeat a predetermined number.

According to another aspect of the present invention, an optical sheet 400 includes a first surface, an array including protrusions 430 formed on the first surface, and a second surface opposite to the first surface. An optical sheet comprising: the second surface is provided with a triangular protrusion 422 and a protrusion 421 having a predetermined curvature in cross section, and the protrusion 430 formed on the first surface has various curvature radii. Have

Next, referring to FIG. 9, the light B1 is emitted by the upper protrusion 430 so that the light moved into the optical sheet 400 according to the present invention is evenly distributed.

As described above, the optical sheet according to the embodiment of the present invention has been described based on the cross-sectional shape in order to clearly describe the optical characteristics, and the protrusions according to the present invention may be linearly formed in the longitudinal direction of the optical sheet.

In addition, the optical sheet having the protrusion according to the present invention can perform all the roles of the conventional diffusion plate, the diffusion sheet and the prism sheet, and as one of the diffusion plates (the optical sheet according to the present invention) can be used, The manufacturing cost of the liquid crystal display device and the backlight assembly of the liquid crystal display device can be reduced.

10 is a photograph showing a luminance distribution in a backlight assembly according to the prior art, and FIG. 11 is a photograph showing a luminance distribution in a backlight assembly using an optical sheet according to the present invention.

In addition, one optical sheet according to the present invention used for the experiment of FIG. 11 is used, and FIG. 10 is a case where a diffusion plate and a diffusion sheet are used together according to the prior art.

The measurement conditions were for the 26-inch TV direct backlight assembly, and the measurement equipment CA-2000 was used when the driving voltage was 24V.

As shown, when the optical sheet according to the present invention is used, it has a 9220 cd / m 2 luminance, but is about 6450 cd / m 2 in the backlight assembly according to the prior art.

Therefore, it can be seen that the luminance is greatly increased by allowing protrusions of different patterns to be formed according to the position of the light source.

The table below is a result of comparing the optical properties of the optical sheet according to the present invention with the conventional diffusion plate.

division Uniformity Luminance gain Conventional diffuser 86 1.30 First embodiment of the present invention 87 1.33 Third embodiment of the present invention 88 1.35

division Uniformity Luminance gain Existing diffuser plate + 3 diffuser sheets 86 1.37 First Embodiment of the Invention + 1 Diffusion Sheet 87 1.41 Embodiment 3 of the Invention + 1 Diffusion Sheet 88 1.43

Table 1 above shows optical properties when the light diffusing sheets according to the first and third embodiments of the present invention are used in place of a conventional diffuser plate in the backlight assembly. The optical characteristic when the case where one general diffusion sheet is laminated | stacked and used together with the optical sheet which concerns on 1st Example and 3rd Example is used by laminating | stacking three diffusion sheets with an existing diffuser plate is shown.

In terms of the brightness of the backlight assembly, the optical sheet according to the present invention appeared to be 1.33 or 1.35 better than that of the conventional diffusion plate, and even when one diffusion sheet was used together with the optical sheet according to the present invention, The luminance characteristics superior to the case where three diffusion sheets were used together with the diffusion plate were obtained.

Therefore, the optical sheet according to the present invention can fully realize the role of the conventional diffusion plate, and furthermore it is possible to simultaneously perform the role of the conventional diffusion plate and the diffusion sheet.

This can significantly reduce the number of sheets used in the direct backlight assembly in the case of using the optical sheet according to the present invention, thereby reducing the manufacturing cost of the backlight assembly.

By the optical sheet and the backlight assembly of the liquid crystal display device provided with the optical sheet as proposed, the light generated from the light source is evenly moved to the liquid crystal display panel side, thereby improving the optical properties of the backlight assembly. .

Claims (18)

delete delete A projection into which light is incident and formed to protrude a predetermined thickness; And It includes a body portion formed on the upper side of the protrusion, The projection is an optical sheet comprising a plurality of first projections having a predetermined curvature in cross section, and a plurality of second protrusions having a prism shape in cross section. The method of claim 3, wherein And the first protrusion is formed so as to be positioned above the light source for generating light. The method of claim 3, wherein And the first protrusion and the second protrusion are alternately formed by repeating a predetermined number. delete A body portion and a protrusion formed to protrude a predetermined thickness from the surface of the body portion, The projection is an optical sheet, characterized in that the embossed first projection, and the first projection and the intaglio second projection is inverted in shape. The method of claim 7, wherein The first protrusion and the second protrusion is formed in consideration of the position of the light source for generating light. The method of claim 7, wherein And the first protrusion is formed above the light source for generating light. delete delete delete A first surface having a plurality of protrusion arrays formed thereon; An optical sheet comprising a second surface opposite the first surface, And a plurality of protrusions having a triangular cross section and a plurality of protrusions having a predetermined curvature on the second surface. The method of claim 13, The protrusions formed on the second surface are arranged linearly along their length direction. The method of claim 14, The formation position of the protrusion part formed in the said 2nd surface and whose cross section has a triangular shape is changed according to the position of the light source which produces light. A lamp for generating light; A reflection plate installed under the lamp and reflecting light generated from the lamp; And An optical sheet provided at an upper side of the lamp and configured to guide incident light toward a liquid crystal display panel; The optical sheet may include a plurality of first protrusions having a predetermined thickness protruding toward the lamp and having a predetermined curvature in cross section, and a plurality of second protrusions having a prism shape in cross section thereof. . The method of claim 16, And wherein the protruding portion has a protruding shape different according to the position of the lamp. delete

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