KR20040041485A - Prism sheet, method for manufacturing thereof and liquid crystal display device using the same - Google Patents

Abstract

A prism sheet having improved luminance and viewing angle, a method of manufacturing the same, and a liquid crystal display using the same are disclosed. By changing the internal angle of the peak portion of the prism-shaped condenser having the function of condensing light and providing it to the liquid crystal display device to have an obtuse angle, and changing the light refractive index of the condenser according to the size of the inner angle of the condenser Increase the light collection efficiency of the light generated by the lamp. Increasing the condensing efficiency of the light emitted from the lamp improves the luminance characteristic which acts as a big factor in evaluating the display device and the viewing angle characteristic which acts as another big factor in evaluating the display device.

Description

PRISM SHEET, MANUFACTURING METHOD AND MANUFACTURING METHOD THEREOF {PRISM SHEET, METHOD FOR MANUFACTURING THEREOF AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME}

The present invention relates to a prism sheet, a manufacturing method thereof and a liquid crystal display device using the same. In particular, the present invention relates to a prism sheet having greatly improved luminance and viewing angle characteristics, a manufacturing method thereof, and a liquid crystal display device using the same.

The prism sheet is widely known as an optical sheet used in a liquid crystal display device (LCD). For example, US Pat. No. 6,354,709, "OPTICAL FILM," has a prism that has a function of condensing light and a function of preventing moiré caused by interference with a pixel pattern of an LCD panel. The sheet is described.

Prism sheet is widely used to be applied to most liquid crystal display devices to increase the display brightness.

1 is a conceptual diagram showing a conventional prism sheet.

Referring to FIG. 1, the conventional prism sheet 100 has a very simple configuration. The prism sheet 100 includes a light exit surface 120 having a smooth light incident surface 110, a plurality of light collecting portions 116 having a triangular pillar shape, and a light incident surface 110 and a light exit surface 120. It has a side 130 for connecting.

In this case, two surfaces of the condenser 116 which face each other and are connected to each other will be defined as a first condensing surface 112 and a second condensing surface 114. In the conventional prism sheet 100, the angle between the peak portions of the first light collecting surface 112 and the second light collecting surface 114 is optimized at 90 °.

2 is a conceptual diagram showing a relationship between a conventional prism sheet and incident light.

Referring to FIG. 2, the prism sheet 100 may be formed at an angle between the incident light 140 and the first condensing surface 112 or the incident light 140 and the second condensing surface 114 that are incident on the light incident surface 110. Therefore, the incident light 140 is reflected or collected and transmitted.

For example, the angle between the peak portions of the light converging portion 116 of the prism sheet 100 is 90 °, and the incident light 140 is angled close to the right angle with respect to the light incident surface 110. When it is assumed to reach, the incident light 140 passes through the light incident surface 110 as it is by Snell's law and reaches the first condensing surface 112. The incident light 140 reaching the first condensing surface 112 is reflected at right angles to the second condensing surface 114. Thereafter, the incident light 140 is reflected back from the second light collecting surface 114 and then exits through the light incident surface 110.

That is, the angle between the peak portions of the light collecting portions 116 of the prism sheet 100 is 90 °, and the incident light 140 may reach the first light collecting surface 112 at an angle of 90 ° with the light incident surface 110. In this case, the incident light 140 may not pass through the prism sheet 100.

Alternatively, when the angle between the peak portions of the light collecting portion 116 of the prism sheet 100 is 90 ° and the incident light 150 reaches the first light collecting surface 112 at an acute angle with respect to the light incident surface 100, The incident light 150 incident on the prism sheet 100 may be emitted from the prism sheet 100.

According to the relation between the prism sheet 100 and the incident light, the prism sheet 100 whose angle between the peak portions of the light converging portion 116 of the prism sheet 100 is optimized by 90 ° is used for a liquid crystal display device using a light guide plate. Very suitable.

3 is a conceptual view of a liquid crystal display device to which a prism sheet having a 90 ° angle between peak portions of a light collecting portion is applied.

Referring to FIG. 3, the conventional liquid crystal display 200 includes a lamp 210, a light guide plate 220, a diffusion plate 230, a prism sheet 100, and a liquid crystal display panel 250. Light generated by the lamp 210 is supplied to the liquid crystal display panel 250 via the light guide plate 220, the diffusion plate 230, and the prism sheet 100.

In this case, the lamp 210 is disposed on the side surface 222 of the light guide plate 220 to reduce the volume of the liquid crystal display 200 to supply light to the side surface 222 of the light guide plate 220. Such a liquid crystal display device 200 is called an edge type liquid crystal display device. The light guide plate 220 emits the supplied light toward the diffuser plate 230, wherein most of the light emitted from the light guide plate 220 has an acute angle with respect to the exit surface 224 of the light guide plate 220. Have

FIG. 4 is a graph measuring front luminance from an upper surface of the diffusion plate of FIG. 3. FIG. 5 is a luminance graph in a state of cutting 90 ° and 270 ° of FIG. 4.

Referring to the graph of FIG. 4 or 5, the light emitted from the surface of the light guide plate 220 is emitted in both directions inclined by about 30 ° from the front surface O , which is mostly perpendicular to the surface of the light guide plate 220. In FIG. 4, reference numerals L1 and L2 are shown in portions where maximum luminance is observed. Referring to FIG. 5, luminance C is observed at two places inclined by about 30 ° from the front surface O of the light guide plate. At this time, the luminance D lower than the luminance C is observed in the front side O portion.

As described above, when the front luminance is lower than the peripheral portion with respect to the front side, display quality is deteriorated, and therefore, a diffusion plate 230 is formed on the upper surface of the light guide plate 220 to improve the front luminance.

However, the prism sheet 100 is disposed on the upper surface of the diffusion plate because it is difficult to greatly improve the front luminance with only the diffusion plate 230.

The prism sheet 100 refracts light incident at an acute angle with respect to the light incident surface 110 of the prism sheet 100, thereby greatly improving the front luminance. As such, in order to increase the front luminance by the prism sheet 100, it is preferable to adjust the angles of the first and second condensing surfaces 112 and 114 of the prism sheet 100 to 90 °.

6 is a conceptual view of another conventional liquid crystal display device.

The conventional liquid crystal display shown in FIG. 6 is a direct type liquid crystal display in which a plurality of lamps are arranged in parallel.

The direct type liquid crystal display device 300 includes a lamp 310, a diffusion plate 320, a prism sheet 100 illustrated in FIG. 1, and a liquid crystal display panel 330. The light path of the direct type liquid crystal display 300 is a lamp 310, a diffusion plate 320, a prism sheet 100, and a liquid crystal display panel 100.

Since the lamp 310 is disposed below the liquid crystal display panel 330 in parallel, most of the light generated by the lamp 310 and passing through the diffusion plate 320 is perpendicular to the light incident surface of the prism sheet 100. Direction, and the remaining minority light has an acute angle with respect to the light incident surface 110 of the prism sheet 100.

The direct type liquid crystal display device has a very different optical path from the edge type liquid crystal display device. Most of the light generated from the lamp of the edge type liquid crystal display is incident inclined to the light incident surface of the prism sheet, and most of the light generated from the lamp of the direct type liquid crystal display is incident to the light incident surface of the prism sheet in the vertical direction. do.

When the angle between the first condensing surface 112 and the second condensing surface 114 of the prism sheet 100 used in the direct type liquid crystal display device is 90 °, the light emitted from the diffuser plate 230 is the prism sheet. After being reflected at 100, it is directed back to diffuser plate 230. Light directed toward the diffuser plate 230 is scattered, extinguished, and lost in the diffuser plate 230.

This is also demonstrated by a simple experiment: light traveling straight at an angle of 90 ° with respect to the light incident plane of the prism sheet 230 having an angle of 90 ° between the first and second condensing surfaces 112. When scanning, it can be seen that a significant amount of light generated by the lamp 310 is reflected from the prism sheet and only a part passes through the prism sheet.

As a result, when the prism sheet used in the edge type liquid crystal display device is applied to the direct type liquid crystal display device as it is, the brightness and viewing angle are greatly reduced, and when the brightness and viewing angle is decreased, the display performance of the direct type liquid crystal display device is also greatly reduced. do.

7 is a graph showing the viewing angle distribution when the prism sheet used in the conventional edge type liquid crystal display is applied to the direct type liquid crystal display. FIG. 8 is a graph illustrating luminance at 90 ° and 270 ° portions of FIG. 7.

Referring to FIG. 7 or 8, only a small amount of light passes from the front side of the direct type liquid crystal display as compared to the edge type liquid crystal display. This is because, as mentioned above, most of the light is reflected from the prism sheet.

6 to 8, a part of light incident from the diffuser plate 320 to the prism sheet 100 near the vertical is emitted in a direction substantially parallel to the prism sheet. This part is shown by reference numerals L3 and L4 in FIG. 7, and by reference numeral F or G in FIG. 8. Light emitted in a direction substantially parallel to the prism sheet cannot be used for the display. Therefore, it is difficult to apply a prism sheet having an angle of 90 degrees between the light collecting portions of the prism sheet to the direct type liquid crystal display device.

U. S. Patent No. 6,354, 709 " OPTICAL FILM " discloses a technique in which the angles of the first and second light collecting surfaces of the prism sheet are extended to 70 to 110 degrees. However, according to US Pat. No. 6,354,709, the brightness improvement effect is extremely small even if the angles of the first condensing surface and the second condensing surface are increased from 90 ° to 110 ° while the light refractive index of the prism sheet is fixed at 1.586. This is because the optical refractive index of the prism sheet and the angle at the first and second condensing surfaces determine the optical properties of the prism sheet. However, US Pat. No. 6,354,709 still has many problems because the optical refractive index is not taken into account.

Accordingly, the present invention has been made in view of the above problems of the prior art, and a first object of the present invention is to provide a prism sheet having a high viewing angle and brightness by changing the optical refractive index and the angle between the light collecting surface.

A second object of the present invention is to provide a method of manufacturing a prism sheet having a high viewing angle and brightness by changing the angle between the light refractive index and the light collecting surface.

It is a third object of the present invention to provide a high quality liquid crystal display device having improved viewing angle and luminance by using a prism sheet having a change in the refractive index and the angle between the light collecting surface.

1 is a conceptual diagram showing a conventional prism sheet.

2 is a conceptual diagram showing a relationship between a conventional prism sheet and incident light.

3 is a conceptual view of a liquid crystal display device to which a prism sheet having a 90 ° angle between peak portions of a light collecting portion is applied.

FIG. 4 is a graph measuring front luminance from an upper surface of the diffusion plate of FIG. 3.

FIG. 5 is a luminance graph in the 90 ° and 270 ° cut states of FIG. 4.

6 is a conceptual view of another conventional liquid crystal display device.

7 is a graph showing the viewing angle distribution when the prism sheet used in the conventional edge type liquid crystal display is applied to the direct type liquid crystal display.

FIG. 8 is a graph illustrating luminance at 90 ° and 270 ° portions of FIG. 7.

9 is a partial cutaway perspective view of a prism sheet according to the present invention.

FIG. 10 is an enlarged view of a portion A of FIG. 9.

11 is a side view of a prism sheet according to an embodiment of the present invention.

12 is a conceptual diagram illustrating one light collecting unit of a prism sheet according to an embodiment of the present invention.

It is a conceptual diagram which shows that curvature was formed in the peak part of the prism sheet by this invention.

14 is a conceptual diagram illustrating a base film formed on the rear surface of the prism sheet according to the present invention.

15 is a conceptual diagram illustrating a first process of manufacturing a prism sheet according to an embodiment of the present invention.

16 is a flowchart illustrating a process of forming a light collecting part on a light refracting thin film.

17 illustrates a liquid crystal display using a prism sheet according to an embodiment of the present invention.

It is a graph which measured the viewing angle of the light radiate | emitted from the prism sheet from the front part.

In order to implement the first object of the present invention, the present invention faces a light incident surface to which light is incident, a light incident surface, and is connected to a first condensing surface and a first condensing surface that are inclined in a first section. The second section connected to the section includes a light exit surface repeatedly formed, and a side connecting the light exit surface and the light incidence surface including a condenser including a second inclined condensing surface, the first condensing surface and the second condenser The angle formed by the light collecting surface provides a prism sheet having an obtuse angle.

In addition, in order to implement the second object of the present invention, the present invention comprises the steps of processing a flowable light refracting material comprising a conditionally cured material cured by an externally applied stimulus in the form of a thin film, in the thin film, Forming an inclined first condensing surface, a second inclined condensing surface repeatedly formed in a second section connected to the first section, and an angle between the first condensing surface and the second condensing surface is an obtuse angle; and It provides a method for producing a prism sheet comprising the step of curing the conditionally cured material.

In addition, in order to implement the third object of the present invention, the present invention provides a lamp assembly in which at least one lamp for generating the first light is arranged in parallel, a diffusion member for emitting the second light diffused by receiving the first light, diffusion The first light converging surface having an inclined surface in the first section for condensing and exiting the light incidence surface disposed above the member and in which the second light is incident, the third light substantially perpendicular to the light incidence surface of the second light; In the second section connected to the first condensing surface and connected to the first section, a condenser including a second condensing surface having a reverse inclined surface is formed repeatedly, and an angle between the first condensing surface and the second condensing surface is obtuse. A liquid comprising a prism sheet including a light exit surface and a side connecting the light exit surface and the light exit surface, and a liquid crystal display panel for converting the fourth light emitted from the light exit surface into a fifth light including information. It provides a display device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

9 is a partial cutaway perspective view of a prism sheet according to the present invention. FIG. 10 is an enlarged view of a portion A of FIG. 9.

Referring to FIG. 10 or 9, the prism sheet 400 includes a light incident surface 410, a light exit surface 420, and a side surface 430.

The light incident surface 410 receives light generated from a lamp or the like and is configured as a smooth surface. The light exit surface 420 has a relationship facing the light incident surface 410, and the side surface 430 connects the light exit surface 420 and the light incident surface 410.

The light exit surface 420 includes a plurality of light collecting parts 440 that protrude continuously from the light exit surface 420. The light collecting part 440 is composed of a first light collecting surface 442 and a second light collecting surface 445. The first condensing surface 442 and the second condensing surface 445 are alternately formed on the light exit surface 420.

11 is a side view of a prism sheet according to an embodiment of the present invention.

Referring to FIG. 11, the first condensing surface 442 is formed over a first section having a first length among the light emitting surfaces 420. The first condensing surface 442 has a first height H1 and is formed to be inclined in the first section. In this case, the first light collecting surface 442 has an inclination angle in a counterclockwise direction with respect to the light incident surface 410.

The second light collecting surface 445 is formed in the second section extending from the first section to the first length. The second light collecting surface 445 is connected to the end of the first light collecting surface 442 having the first height H1 from the light exit surface 420. Therefore, the second condensing surface 445 is formed to be inclined reversely to reach the light exit surface 420 by gradually lowering the height from the first height H1. In this case, the second light collecting surface 445 has a reverse tilt angle in the clockwise direction with respect to the light incident surface 410. The inclination angle of the first light collecting surface 442 with respect to the light incident surface 410 and the reverse inclination angle of the second light collecting surface 445 with respect to the light incident surface 410 are the same.

Meanwhile, an angle formed between the first light collecting surface 442 and the second light collecting surface 445 included in each light collecting part 440 has an obtuse angle. In addition, the prism sheet 400 has an optical refractive index that increases in proportion to the size of the angle formed between the first and second condensing surfaces 442 and 445 of the condenser 440.

As such, when the angle between the first condensing surface 442 and the second condensing surface 445 of the prism sheet 400 is formed at an obtuse angle, the light incident to the light incident surface 410 is substantially close to 90 °. The light is condensed from the first light collecting surface 442 and the second light collecting surface 445 and then emitted.

To implement this, the angle formed by the first light collecting surface 442 and the second light collecting surface 445 is greater than 90 degrees and smaller than 140 degrees. Preferably, the angle formed between the first condensing surface 442 and the second condensing surface 445 may be greater than 110 degrees and less than 140 degrees. In addition, the optical refractive index of the light collecting part 440 is changed between 1.40 and 1.70 depending on the angle formed between the first light collecting surface 442 and the second light collecting surface 445 of the light collecting part 440.

12 is a conceptual diagram illustrating one light collecting unit of a prism sheet according to an embodiment of the present invention. 12 illustrates incident light 450 incident at right angles to the light incident surface 410 of the prism sheet 400 according to the angle between the first and second condensing surfaces 442 and 445 of the prism sheet 400. Is shown.

Referring to FIG. 12, the light refractive index n _a of air is 1, and the light refractive index n _p of the prism sheet is selected from 1.40 to 1.70.

In this case, as shown in FIG. 12, an angle formed by normals (N) normal to the first light collecting surface 442 and incident light 450 incident at an angle of 90 ° with respect to the light incident surface 410 is illustrated. It is defined as β °.

In addition, an angle formed by the first light collecting surface 442 and the second light collecting surface 445 will be defined as α °. In addition, an angle formed by the normal line N and the outgoing light 455 emitted from the first light collecting surface 442 will be defined as γ ° (gamma). The angle formed by the light emitted from the first light collecting surface 442 based on the direction perpendicular to the light incident surface 410 is determined. This will be defined.

In FIG. 12 and Equation 1, the prism incidence angle β ° and the angle angle α ° are all in degrees, and 90 ° is in radians. to be.

In FIG. 12 and Equation 2, the prism exit angle γ ° is a degree unit, and n _p is a refractive index of the prism sheet 400.

) = 90 °- γ °

Hereinafter, the prism sheet shown in FIG. 11 or 12 with respect to the optical refractive index 1.41 to 1.49, the optical refractive index 1.51 to 1.59 and the optical refractive index 1.61 to 1.69 through <Equation 1>, <Equation 2> and <Equation 3> When the angle between the light collecting part 440 of 400 is increased from 79 ° to 140 °, the angle change perpendicular to the emission light 455 will be described. In this case, the viewing angle and the luminance are changed according to the angle and the light refractive index formed by the emitted light 455 and the vertical.

<Table 1> selects any one of 1.41 to 1.49, for example, 1.4 as the optical refractive index of the prism sheet 400 shown in FIG. 11 or 12, and the first and second condensing surfaces 442 and 442 are shown. A diagram simulating the distribution of light emitted from the prism sheet while changing the angle between 445 to 79 °.

Prism Inter Angle Prism incident angle (β °) Prism emission angle (γ °) Exit angle for vertical ( ) Simulation conditions: Prism refractive index (n _p ) 1.41 to 1.49, in one embodiment 1.4 140 ° 20 ° 14.14 ° 5.86 ° 130 ° 25 ° 17.57 ° 7.43 ° 125 ° 27.5 ° 19.25 ° 8.24 ° 122 ° 29 ° 20.26 ° 8.74 ° 120 ° 30 ° 20.92 ° 9.07 ° 117 ° 31.5 ° 21.91 ° 9.58 ° 115 ° 32.5 ° 22.56 ° 9.93 ° 111 ° 34.5 ° 23.86 ° 10.63 ° 110 ° 35 ° 24.18 ° 10.81 ° 105 ° 37.5 ° 25.77 ° 11.72 ° 103 ° 38.5 ° 26.40 ° 12.09 ° 101 ° 39.5 ° 27.02 ° 12.47 ° 100 ° 40 ° 27.33 ° 12.66 ° 98 ° 41 ° 27.94 ° 13.05 ° 97 ° 41.5 ° 28.25 ° 13.25 ° 96 ° 42 ° 28.55 ° 13.44 ° 90 ° 45 ° 30.33 ° 14.66 ° 89 ° 45.5 ° 30.63 ° 14.87 ° 88 ° 46 ° 30.92 ° 15.08 ° 85 ° 47.5 ° 31.78 ° 15.72 ° 80 ° 50 ° 33.17 ° 16.82 ° 79 ° 50.5 ° 33.45 ° 17.05 °

First, in Table 1, the prism incidence angle β ° is the angle between the peak portions of the first condensing surface 442 and the second condensing surface 445 at the interposition angle α °, which is a variable in Equation 1. Is calculated by substituting one selected from 79 ° to 140 °.

For example, when the angle α is 110 °, the prism incident angle β ° is 90 °- By 35 °.

Subsequently, a prism emission angle γ °, which is an angle of light emitted from the prism sheet with respect to the direction perpendicular to the light incidence plane 110, is calculated using Equation (2).

In order to calculate the prism exit angle γ °, for example, 1.4 of the optical refractive indices of 1.41 to 1.49 is selected for n _p in Equation 2, and the substitution and the previously calculated prism incidence angle β ° are substituted. For example, if the prism exit angle (γ °) is n _p is 1.4 and the angle is 110 °, This calculation yields 24.18 °. In this case, the calculation is performed in units of degrees.

When the prism incidence angle β and the prism emission angle γ ° are calculated by Equation 1, the emission angle with respect to the vertical ) Can be calculated. Exit angle for vertical ( ) Is calculated by Equation 3. For example, the exit angle for vertical ( ) Is 90 °- -24.18 ° makes it about 10.81 °.

At this time, the exit angle for the vertical ( ) Is closer to zero, the vertical luminance increases significantly, and the exit angle to vertical ( Increasing) decreases the vertical luminance.

Referring to Table 1, the luminance distribution has a light index of refraction of 1.41 to 1.49 of the prism sheet 400, and a peak portion of the first and second condensing surfaces 442 and 445 of the prism sheet 400. When the angle between is within 60 ° to 90 °, the incident light 450 is very difficult to exit from the prism sheet 400, and even when exiting from the prism sheet 400, the angle formed with the vertical becomes very large so that the front viewing angle and the front luminance are increased. It is greatly reduced.

In general, in a liquid crystal display device using a light guide plate, since the angle emitted from the light guide plate is emitted in a direction inclined with respect to the surface of the light guide plate, the angle between the two light collecting surfaces of the prism sheet is optimized at 90 degrees. On the other hand, in a liquid crystal display device not using a light guide plate, when a prism sheet having an angle of 90 ° between two light collecting surfaces is used, the luminance and viewing angle characteristics are rather deteriorated.

According to the present embodiment, in the liquid crystal display device which does not use the light guide plate, the luminance and viewing angle characteristics can be improved by making the angle between the two light collecting surfaces of the prism sheet larger than 90 degrees and about 140 degrees. Preferably, by setting the angle between the two light collecting surfaces of the prism sheet to be greater than 110 ° and less than or equal to 140 °, the luminance and viewing angle can be further improved.

On the other hand, the light emitted in a section in which the angle between the peak portions of the first condensing surface 442 and the second condensing surface 445 of the prism sheet 400 is 140 ° or more increases in brightness, but greatly reduces the viewing angle. It is not preferable to apply to a TV or the like. Therefore, the prism sheet having an angle of 140 ° or more between the peak portions of the first light collecting surface 442 and the second light collecting surface 445 is preferably applied to a liquid crystal display device in which luminance characteristics are more important than viewing angle characteristics.

Luminance required for display in an interval between a peak portion of the first light collecting surface 442 and the second light collecting surface 445 of the prism sheet 400 larger than 90 ° and smaller than 140 °, in particular, between 90 ° and 120 °. Is increased more and the viewing angle distribution at the front is also increased.

<Table 2> selects any one of 1.51 to 1.59 as the optical refractive index of the prism sheet, and sets the angle between the first and second condensing surfaces 442 and 445 shown in FIG. 11 or 12. It is a table simulating the distribution of the light emitted from the prism sheet 400 while changing from ° to 140 °.

Prism Inter Angle Prism incident angle (β °) Prism emission angle (γ °) Exit angle for vertical ( ) Simulation conditions: Prism refractive index (n _p ) 1.51 to 1.59, in one embodiment 1.5 140 ° 20 ° 13.18 ° 6.82 ° 130 ° 25 ° 16.36 ° 8.63 ° 125 ° 27.5 ° 17.93 ° 9.57 ° 122 ° 29 ° 18.85 ° 10.14 ° 120 ° 30 ° 19.47 ° 10.52 ° 117 ° 31.5 ° 20.38 ° 11.11 ° 115 ° 32.5 ° 20.99 ° 11.51 ° 111 ° 34.5 ° 22.18 ° 12.31 ° 110 ° 35 ° 22.48 ° 12.51 ° 105 ° 37.5 ° 23.94 ° 13.55 ° 103 ° 38.5 ° 24.52 ° 13.97 ° 101 ° 39.5 ° 25.09 ° 14.40 ° 100 ° 40 ° 25.37 ° 14.62 ° 98 ° 41 ° 25.93 ° 15.06 ° 97 ° 41.5 ° 26.21 ° 15.28 ° 96 ° 42 ° 26.49 ° 15.50 ° 90 ° 45 ° 28.12 ° 16.87 ° 89 ° 45.5 ° 28.39 ° 17.10 ° 88 ° 46 ° 28.65 ° 17.34 ° 85 ° 47.5 ° 29.44 ° 18.05 ° 80 ° 50 ° 30.71 ° 19.28 ° 79 ° 50.5 ° 30.96 ° 19.53 °

First, in Table 2, the prism incidence angle β ° is the angle between the peak portions of the first condensing surface 442 and the second condensing surface 445 at the inter angle α °, which is a variable in Equation 1. Is calculated by substituting one selected from 79 ° to 140 °.

For example, when the angle α is 110 °, the prism incident angle β ° is 90 °- By 35 °.

Subsequently, a prism emission angle γ °, which is an angle of light emitted from the prism sheet with respect to the direction perpendicular to the light incidence plane 110, is calculated using Equation (2).

In order to calculate the prism exit angle γ °, Equation 2 selects 1.5 out of the optical refractive indices 1.51 to 1.59 and substitutes n _p in the equation 2 and substitutes the prism incident angle β previously calculated. If the prism exit angle (γ °) is n _p is 1.5 and the angle is 110 °, This calculation yields 22.48 °. In this case, the calculation is performed in units of degrees.

When the prism incidence angle β and the prism emission angle γ ° are calculated by Equation 1, the emission angle with respect to the vertical ) Can be calculated. Exit angle for vertical ( ) Is calculated by Equation 3. For example, the exit angle for vertical ( ) Is 90 °- -22.48 ° means about 12.52 °.

At this time, the exit angle for the vertical ( ) Is closer to zero, the vertical luminance increases significantly, and the exit angle to vertical ( Increasing) decreases the vertical luminance.

Referring to Table 2, the luminance distribution has a light index of refraction of 1.51 to 1.59 of the prism sheet 400, and a peak portion of the first and second condensing surfaces 442 and 445 of the prism sheet 400. When the angle between is within 60 ° to 90 °, the incident light 450 is very difficult to exit from the prism sheet 400, and even when exiting from the prism sheet 400, the angle formed with the vertical becomes very large so that the front viewing angle and the front luminance are increased. It is greatly reduced.

In general, in a liquid crystal display device using a light guide plate, since the angle emitted from the light guide plate is emitted in a direction inclined with respect to the surface of the light guide plate, the angle between the two light collecting surfaces of the prism sheet is optimized at 90 degrees. On the other hand, in a liquid crystal display device not using a light guide plate, when a prism sheet having an angle of 90 ° between two light collecting surfaces is used, the luminance and viewing angle characteristics are rather deteriorated.

According to the present embodiment, in the liquid crystal display device which does not use the light guide plate, the luminance and viewing angle characteristics can be improved by making the angle between the two light collecting surfaces of the prism sheet larger than 90 degrees and about 140 degrees. Preferably, by setting the angle between the two light collecting surfaces of the prism sheet to be greater than 110 ° and less than or equal to 140 °, the luminance and viewing angle can be further improved.

On the other hand, the light emitted in a section in which the angle between the peak portions of the first condensing surface 442 and the second condensing surface 445 of the prism sheet 400 is 140 ° or more increases in brightness, but greatly reduces the viewing angle. It is not preferable to apply to a TV or the like. Therefore, the prism sheet having an angle of 140 ° or more between the peak portions of the first light collecting surface 442 and the second light collecting surface 445 is preferably applied to a liquid crystal display device in which luminance characteristics are more important than viewing angle characteristics.

Luminance required for display in an interval between a peak portion of the first light collecting surface 442 and the second light collecting surface 445 of the prism sheet 400 larger than 90 ° and smaller than 140 °, in particular, between 90 ° and 120 °. Is increased more and the viewing angle distribution at the front is also increased.

Table 3 shows that the refractive index of the prism sheet is selected from 1.61 to 1.69, and is emitted from the prism sheet while changing the angle between the first condensing surface 442 and the second condensing surface 445 from 79 ° to 140 °. This table simulates the distribution of light.

Prism Inter Angle Prism incident angle (β °) Prism emission angle (γ °) Exit angle for vertical ( ) Simulation conditions: Prism refractive index (n _p ) 1.61 to 1.69, in one embodiment 1.6 140 ° 20 ° 6.82 ° 12.34 ° 130 ° 25 ° 8.63 ° 15.13 ° 125 ° 27.5 ° 9.57 ° 16.77 ° 122 ° 29 ° 10.14 ° 17.63 ° 120 ° 30 ° 10.52 ° 18.21 ° 117 ° 31.5 ° 11.11 ° 19.06 ° 115 ° 32.5 ° 11.51 ° 19.62 ° 111 ° 34.5 ° 12.31 ° 20.73 ° 110 ° 35 ° 12.51 ° 21.00 ° 105 ° 37.5 ° 13.55 ° 22.36 ° 103 ° 38.5 ° 13.97 ° 22.89 ° 101 ° 39.5 ° 14.40 ° 23.42 ° 100 ° 40 ° 14.62 ° 23.68 ° 98 ° 41 ° 15.06 ° 24.20 ° 97 ° 41.5 ° 15.28 ° 24.46 ° 96 ° 42 ° 15.50 ° 24.72 ° 90 ° 45 ° 16.87 ° 26.23 ° 89 ° 45.5 ° 17.10 ° 26.47 ° 88 ° 46 ° 17.34 ° 26.71 ° 85 ° 47.5 ° 18.05 ° 27.44 ° 80 ° 50 ° 19.28 ° 28.60 ° 79 ° 50.5 ° 19.53 ° 28.83 °

First, in Table 3, the prism incidence angle β ° is the angle between the peak portions of the first condensing surface 442 and the second condensing surface 445 at the inter angle α ° which is a variable in Equation 1. Is calculated by substituting one selected from 79 ° to 140 °.

For example, when the angle α is 110 °, the prism incident angle β ° is 90 °- By 35 °.

Subsequently, a prism emission angle γ °, which is an angle of light emitted from the prism sheet with respect to the direction perpendicular to the light incidence plane 110, is calculated using Equation (2).

In order to calculate the prism exit angle γ °, n _p is selected in Equation 2, and 1.6 of the optical refractive indices 1.61 to 1.69 is substituted, and the prism incident angle β previously calculated is substituted. The prism exit angle γ is 1.5 when n _p is 1.5 and the angle is 110 °. This calculation yields 21.00 °. In this case, the calculation is performed in units of degrees.

When the prism incidence angle β and the prism emission angle γ ° are calculated by Equation 1, the emission angle with respect to the vertical ) Can be calculated. Exit angle for vertical ( ) Is calculated by Equation 3. For example, the exit angle for vertical ( ) Is 90 °- It becomes about 14.00 degrees by 21.00 degrees.

At this time, the exit angle for the vertical ( ) Is closer to zero, the vertical luminance increases significantly, and the exit angle to vertical ( Increasing) decreases the vertical luminance.

Referring to Table 3, the luminance distribution has a light refractive index of 1.61 to 1.69 of the prism sheet 400, and a peak portion of the first and second condensing surfaces 442 and 445 of the prism sheet 400. When the angle between is within 60 ° to 90 °, the incident light 450 is very difficult to exit from the prism sheet 400, and even when exiting from the prism sheet 400, the angle formed with the vertical becomes very large so that the front viewing angle and the front luminance are increased. It is greatly reduced.

In general, in a liquid crystal display device using a light guide plate, since the angle emitted from the light guide plate is emitted in a direction inclined with respect to the surface of the light guide plate, the angle between the two light collecting surfaces of the prism sheet is optimized at 90 degrees. On the other hand, in a liquid crystal display device not using a light guide plate, when a prism sheet having an angle of 90 ° between two light collecting surfaces is used, the luminance and viewing angle characteristics are rather deteriorated.

According to the present embodiment, in the liquid crystal display device which does not use the light guide plate, the luminance and viewing angle characteristics can be improved by making the angle between the two light collecting surfaces of the prism sheet larger than 90 degrees and about 140 degrees. Preferably, by setting the angle between the two light collecting surfaces of the prism sheet to be greater than 110 ° and less than or equal to 140 °, the luminance and viewing angle can be further improved.

On the other hand, the light emitted in a section in which the angle between the peak portions of the first condensing surface 442 and the second condensing surface 445 of the prism sheet 400 is 140 ° or more increases in brightness, but greatly reduces the viewing angle. It is not preferable to apply to a TV or the like. Therefore, the prism sheet having an angle of 140 ° or more between the peak portions of the first light collecting surface 442 and the second light collecting surface 445 is preferably applied to a liquid crystal display device in which luminance characteristics are more important than viewing angle characteristics.

Luminance required for display in an interval between a peak portion of the first light collecting surface 442 and the second light collecting surface 445 of the prism sheet 400 larger than 90 ° and smaller than 140 °, in particular, between 90 ° and 120 °. Is increased more and the viewing angle distribution at the front is also increased.

It is a conceptual diagram which shows that curvature was formed in the peak part of the prism sheet by this invention.

Referring to FIG. 13, a curved surface 444 is formed at a peak portion of the prism sheet 400 where the first condensing surface 445 and the second condensing surface 442 meet.

The curved surface 444 forms the luminance distribution of the light emitted from the prism sheet 400 more uniformly.

At this time, the projection length W1 of the curved surface 444 is preferably within 5% to 20% of the total projection length W2 of the first light collecting surface 442 and the second light collecting surface 445.

14 is a conceptual diagram illustrating a base film formed on the rear surface of the prism sheet according to the present invention.

Referring to FIG. 14, the prism sheet 400 is preferably made of a material having a light refractive index between 1.40 and 1.70. However, the prism sheet 400 is similar to the prism sheet 400 while being transparent to the rear surface of the prism sheet 400. The base film 460 having the optical refractive index may be formed.

The prism sheet 400 having such a configuration may be made of a material such as polycarbonate, polyester, polyethylene terephthalate (PET), or a mixture thereof.

Hereinafter, a process of manufacturing a prism sheet having such a configuration will be described with reference to the accompanying drawings.

15 is a conceptual diagram illustrating a first process of manufacturing a prism sheet according to an embodiment of the present invention.

Referring to FIG. 15, first, a flowable light refracting material 443 including a conditional curing material cured by an externally applied magnetic pole is applied to the base body 460 in a thin film form. Hereinafter, the light refraction material applied to the base body 460 will be referred to as a light refraction thin film, and the reference numeral 443 will be given.

At this time, it is preferable to use the ultraviolet curable material hardened | cured by ultraviolet-ray as a conditional hardening material. The flowable light refraction material is made of a material such as polycarbonate, polyester, polyethylene terephthalate, or a mixture thereof. At this time, the optical refractive index of the optical refraction material is preferably selected from 1.40 to 1.70.

16 is a conceptual diagram illustrating a process of forming a light collecting part on a light refracting thin film.

Referring to FIG. 16, the surface of the light refracting thin film 443 is pressed by a cylindrical stamper 515 having a pattern 510 having a shape opposite to that of the light collecting portion shown in FIG. 11. As a result, the surface of the optical refraction thin film 443 is inclined in the first section having the first length and is connected to the first condensing surface 442 and the first condensing surface 442 having the first height, and from the first section. A second condensing surface 445 is formed which extends by the first length and is inclined. The cylindrical stamper 515 is pressurized while rotating the surface of the light refracting thin film 443 so that the condenser 440 is continuously formed on the surface of the light refracting thin film 443.

The ultraviolet light 535 is again scanned by the ultraviolet ray scanning device 530 to the light collecting portion 440 processed by the cylindrical stamper 515. The ultraviolet curable material included in the light collecting part 440 by the ultraviolet ray 535 is cured to produce a prism sheet 400 as illustrated in FIG. 11.

At this time, the angle between the first condensing surface 442 and the second condensing surface 445 of the prism sheet 400 is an obtuse angle, preferably between the first condensing surface 442 and the second condensing surface 445. Has an angle greater than 90 ° and less than 140 °.

17 illustrates a liquid crystal display using a prism sheet according to an embodiment of the present invention.

Referring to FIG. 17, the liquid crystal display 700 is generally composed of a lamp assembly 710, a diffusion plate 720, a prism sheet 400, and a liquid crystal display panel assembly 730.

The lamp assembly 710 consists of at least one lamp 714 that generates light. The lamp assembly 710 is preferably composed of a plurality of lamps, each lamp 714 is arranged in parallel.

The light generated by the lamp assembly 710 having such a configuration has a non-uniform brightness because the lamps 714 are spaced apart from each other. Specifically, the brightness is higher as the lamp 714 gets closer, and has a relatively low brightness between the lamp 714 and the lamp 714.

Nevertheless, in order to have a uniform brightness at the top of the lamps 714, the diffusion plate 720 is installed on the top of the lamp assembly 710.

The diffuser plate 720 changes the path of the light so that the light generated by the lamp assembly 710 has a direction perpendicular to the diffuser and the diffuser plate 720.

The prism sheet 400 for condensing light generated by the diffusion plate 720 is provided on the diffusion plate 720.

Since the prism sheet 400 and its manufacturing method have been described in detail with reference to the drawings below in FIG. 9, duplicate description thereof will be omitted. Hereinafter, the same names and reference numerals as those described above will be used for the parts related to the prism sheet 400.

Most of the light incident on the light incident surface 410 of the prism sheet 400 has an optical distribution close to a right angle with respect to the diffusion plate 720. The prism sheet 400 is configured such that the angle formed between the first and second condensing surfaces 442 and 445 of the condenser 440 is an obtuse angle, preferably greater than 90 ° and smaller than 140 ° so that the diffusion plate 720 is formed. Most of the light emitted from the light is focused and emitted. Alternatively, the prism sheet 400 may be configured such that an angle formed between the first condensing surface 442 and the second condensing surface 445 of the condenser 440 is preferably larger than 110 ° and smaller than 140 °.

It is a graph which measured the viewing angle of the light radiate | emitted from the prism sheet from the front part.

Referring to FIG. 18, by adjusting an angle between the light collecting units 440 in the direct type liquid crystal display, light emitted from the prism sheet in a direction substantially parallel to the prism sheet as shown in FIG. 7 or 8 is known. It does not exist, and therefore, the luminance of the light emitted from the prism sheet 400 shown in FIG. 17 is improved, and the viewing angle is also improved.

The liquid crystal display panel 700 converts the light emitted from the prism sheet 400 into image light including an image. In this case, since the light incident on the liquid crystal display panel 700 is incident to the liquid crystal display panel 700, the front viewing angle is excellent, and the luminance is greatly increased to perform high quality display.

As described in detail above, the optical refractive index is changed according to the angle and the angle between the light collecting parts formed on the prism sheet, and thus the image can be displayed at a higher luminance and a better viewing angle.

In the detailed description of the present invention described above with reference to a preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge in the scope of the invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (20)

The light incident surface to which light is incident, the first condensing surface facing the light incidence surface and inclined in a first section, the second condensing surface inclined in reverse in a second section connected to the first condensing surface and connected to the first section. And a light exit surface repeatedly formed, and a side connecting the light exit surface and the light incident surface, wherein the angle between the first and second light condensing surfaces of the light converging portion is an obtuse angle. Prism sheet, characterized in that. 2. The method of claim 1, wherein the angle of incidence is greater than 90 ° and less than 140 ° in order to transmit the light incident at an angle substantially close to the light incident plane, in proportion to the magnitude of the angle between the angles. The refractive index of the light collecting portion is increased, characterized in that the prism sheet. The prism sheet according to claim 2, wherein the light refractive index of the light collecting portion is 1.4 to 1.7. The light collecting part according to claim 1, wherein the angle between the light beams is greater than 90 ° and less than 140 ° so as to transmit the light incident at an angle substantially close to the right angle to the light incidence plane, and to further improve the brightness. The said optical refractive index of is 1.41-1.49, The prism sheet characterized by the above-mentioned. The method of claim 1, wherein the angle between the angle is greater than 90 ° and less than 140 °, and the optical refractive index is between 1.50 and 1.59 to transmit the light incident at an angle substantially close to the light incident surface Prism sheet, characterized in that. The method of claim 1, wherein the angle between the angle is greater than 90 ° and less than 140 °, and the optical refractive index is 1.60 to 1.70 to transmit the light incident at an angle substantially close to the right angle to the light incident surface A prism sheet characterized by the above. 2. The method of claim 1, wherein the angle of incidence is greater than 110 ° and less than 140 ° in order to transmit the light incident at an angle substantially close to the light incident plane, in proportion to the magnitude of the angle of incidence. The refractive index of the light collecting portion is increased, characterized in that the prism sheet. The prism sheet of claim 1, further comprising a base body having the same refractive index as that of the light collecting portion on the light incident surface. The prism sheet according to claim 1, wherein a boundary between the first condensing surface and the second condensing surface is curved. The prism sheet according to claim 9, wherein the curved length is 5% to 20% with respect to the bottom width of the light converging portion. The prism sheet of claim 1, wherein the light collecting part is made of a material selected from the group consisting of polycarbonate, polyester, and polyethylene terephthalate. Processing the flowable light refracting material in a thin film form including a conditionally cured material cured by an externally applied stimulus; In the thin film, a first condensing surface inclined in a first section and a second condensing surface inclined in reverse in a second section connected to the first section are formed repeatedly, and an angle between the first condensing surface and a second condensing surface is formed. Forming a light collecting portion that is obtuse; And And curing the conditionally cured material. The method of manufacturing a prism sheet according to claim 12, wherein the forming of the light collecting part is performed by forming the convex angle greater than 90 degrees and less than 140 degrees. The method of manufacturing a prism sheet according to claim 12, wherein the forming of the light collecting part is performed by forming the convex angle larger than 110 ° and less than 140 °. The prism of claim 12, wherein the light refractive index of the flowable light refracting material is adjusted between 1.4 and 1.7 prior to processing the flowable light refracting material including the conditional curable material into a thin film form. Method of manufacturing the sheet. The method of manufacturing a prism sheet according to claim 12, wherein the forming of the light converging portion forms the inter-angle angle greater than 90 degrees and smaller than 120 degrees. A lamp assembly in which at least one lamp for generating a first light is arranged in parallel; A diffusion member configured to emit the second light diffused by the first light; An inclined surface is disposed in the first section in order to collect and emit a light incident surface disposed on the diffusion member and the third light that is substantially perpendicular to the light incident surface of the second light is incident. A first light collecting surface having a second light collecting surface having a second light collecting surface having a reverse inclined surface in a second section connected to the first light collecting surface and connected to the first section; A prism sheet including a light exit surface having an obtuse angle between planes and a side surface connecting the light exit surface and the light exit surface; And And a liquid crystal display panel for converting the fourth light emitted from the light exit surface into a fifth light including information. 18. The liquid crystal display device according to claim 17, wherein the angle is greater than 90 degrees and less than 140 degrees. 18. The liquid crystal display device according to claim 17, wherein the angle is greater than 90 degrees and less than 120 degrees. 18. The liquid crystal display device according to claim 17, wherein the angle is greater than 110 degrees and less than 140 degrees.