KR101441382B1 - A prism sheet and the fabrication method, a backlight unit and a liquid crystal display device having the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prism sheet capable of improving hot spots, color unevenness, and brightness, a method of manufacturing the prism sheet, and a backlight unit and a liquid crystal display having the same.

A prism sheet according to the present invention includes: a first prism sheet having an acid (?) Shape on an upper surface and a lower surface; And a second prism sheet having the same refractive index as the first prism sheet and having an upper surface formed along a lower surface of the first prism sheet, wherein an upper surface of the first prism sheet and an upper surface of the second prism sheet .

According to the present invention, the first prism sheet and the second prism sheet can concentrate and disperse light, thereby preventing a bright line generated in the light-incident portion of the backlight unit using the lamp, It is possible to prevent mura phenomenon. Further, the first prism sheet refracts the light refracted and incident on the second prism sheet, refracts the incident light, vertically condenses the light, and disperses the light, thereby improving the brightness of the liquid crystal display device.

Prism sheet, hot spot, colorless

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prism sheet, a prism sheet, a method of manufacturing the same and a backlight unit and a liquid crystal display having the prism sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a prism sheet capable of improving hot spots, color unevenness, and brightness, a method of manufacturing the same and a backlight unit and a liquid crystal display having the same.

2. Description of the Related Art In recent years, various flat panel display devices that can reduce weight and volume, which are disadvantages of cathode ray tubes (CRTs), are emerging. Examples of such flat panel display devices include a liquid crystal display, a field emission display, a plasma display panel, and a light emitting display device.

2. Description of the Related Art Generally, a liquid crystal display device is in a trend of widening its application range due to features such as light weight, thinness, and low power consumption driving. According to this tendency, the liquid crystal display device is used as a portable computer such as a notebook PC, an office automation device, an audio / video device, an indoor and outdoor advertisement display device, etc. With recent achievements of mass production technology and research and development, It is rapidly developing.

Such a liquid crystal display device displays an image by adjusting the light transmittance of the liquid crystal using an electric field. To this end, the liquid crystal display device includes a liquid crystal panel having a liquid crystal cell, a backlight unit for applying light to the liquid crystal panel, and a driving circuit for driving the liquid crystal cell.

In this case, since the liquid crystal panel of the liquid crystal display device is a light-receiving device that displays an image by adjusting the amount of a light source coming from the outside, a back light unit, which is a separate light source for irradiating light to the liquid crystal panel, do. Such a backlight unit is classified into an edge type and a direct type according to the installed position.

Here, the edge type backlight unit is formed on both sides of the liquid crystal panel, and includes a lamp for generating light and a light guide plate for guiding the light generated from the lamp toward the liquid crystal panel, a lamp housing for protecting the lamp, And a plurality of optical sheets formed on the lamp housing and the light guide plate and uniformly transmitting light toward the liquid crystal panel.

The plurality of optical sheets include a diffusion sheet for diffusing the light emitted from the diffusion plate to the entire area of the liquid crystal panel and a prism sheet for raising the progress angle of light diffused by the diffusion sheet in the vertical direction of the liquid crystal panel .

A prism sheet used for such a backlight unit is divided into a forward prism sheet and a reverse prism sheet according to a method of condensing or diffusing light.

In the backlight unit using the backward prism sheet 10, the amount of light is concentrated at the light-incident portion of the light guide plate 30 and the light of the light source 20, which is totally reflected inside the light guide plate 30, Is emitted to the prism sheet 10 at 72 degrees with respect to the normal (dotted line). At this time, since the backward prism sheet 10 vertically converges the light of the light source 20 using the total reflection, the light converging efficiency is increased but the refractive index dispersion is less than that of the forward prism sheet. Therefore, in the case of the backward prism sheet 10 using the light source 20 as a lamp, a bright spot is generated at the light entrance portion of the light guide plate 30, and a hot spot or color unevenness occurs when the light source is an LED .

The backlight unit using the forward prism sheet 40 is configured such that the light of the light source 60 is incident at 72 degrees with respect to the normal line (dotted line) like the backlight unit using the backward prism sheet 10, And exits in the direction of the sheet 40. The emitted light is supplied to a BEF (Brightness Enhancement Film) 50 in order to increase the brightness. The intensity of the light passing through the BEF 50 and supplied to the forward prism sheet 40 is emitted from the light source 60 Which is lower than the main emitted light. The backlight unit using the forward prism sheet can improve the hot spot and the color unevenness by dispersing the light of the light source, but has a problem that the brightness is reduced by 30% or more as compared with the backward prism sheet 10.

In order to solve the above-mentioned problems, the present invention provides a prism sheet capable of improving the hot spot, color unevenness and brightness by simultaneously forming forward and backward prism sheets, a method of manufacturing the prism sheet and a backlight unit and a liquid crystal display Device.

A prism sheet according to the present invention includes: a first prism sheet having an acid (?) Shape on first and second surfaces; And a second prism sheet having a refractive index different from that of the first prism sheet and corresponding to one of the surfaces of the first prism sheet.

A method of manufacturing a prism sheet according to an embodiment of the present invention includes: preparing a first prism sheet; Passing the first prism sheet through an acid type roller to form a first prism sheet having first and second surfaces in acid form; Applying a UV curable resin to either side of the first prism sheet; Planarizing the applied UV curable resin using a roller; And curing the UV curable resin to form a second prism sheet.

A method of manufacturing a prism sheet according to another embodiment of the present invention includes: preparing a base film; Applying a first UV curable resin to a first side of the base film; Passing the first UV curable resin through an acid type roller to form a first side of the base film in an acid form; Curing an acidic UV curable resin on the first side of the base film; Forming a second UV curable resin on the cured base film; Curing the second UV curable resin to form a second prism sheet; Applying a third UV curable resin to a second side of the base film; Passing the third UV curable resin through an acid type roller to form an acid form; And curing the third UV curable resin to form a first prism sheet.

A prism sheet, a method of manufacturing the same, and a backlight unit and a liquid crystal display having the prism sheet according to the present invention can prevent a bright line generated in a light-incoming portion of a backlight unit using a lamp by focusing and dispersing light in the first and second prism sheets. And it is possible to prevent a hot spot or a color unevenness of the backlight unit using the LED. Further, the first prism sheet refracts the light refracted and incident on the second prism sheet, refracts the incident light, vertically condenses the light, and disperses the light, thereby improving the brightness of the liquid crystal display device.

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

2 is a view showing a prism sheet according to an embodiment of the present invention.

Referring to FIG. 2, a prism sheet according to an embodiment of the present invention includes a first prism sheet 104 having an acid (?) Shape on first and second surfaces, a first prism sheet 104 having a different refractive index And a second prism sheet 102 formed on one surface of the first prism sheet 104 and corresponding to the shape of the first prism sheet 104.

The first prism sheet 104 is formed to have an acid shape on the first and second surfaces. The first prism sheet 104 refracts light (2) supplied from the second prism sheet 102 to form a liquid crystal panel (not shown) so that light can be irradiated vertically (). Here, the first prism sheet 104 may be formed of the same material as or different from the second prism sheet 102. At this time, the first prism sheet 104 is formed of a polycarbonate series or an acrylic resin series.

The second prism sheet 102 is formed to correspond to the shape on either side of the first prism sheet 104. Here, the second prism sheet 102 refracts light (?) Irradiated from a light source (not shown) (?) And supplies it to the sheet of the first prism 104. At this time, the second prism sheet 102 is formed to be equal to or larger than the refractive index of the first prism sheet 104. In addition, the second prism sheet 102 is formed of an acryl resin series.

Referring to FIG. 2, the first and second prism sheets 102 and 104 are arranged such that light (1) incident from the outside passes through the incident surface of the second prism sheet 102, (2)), and is again refracted and diffused on the inclined surface of the second prism sheet 102 using the principle of the forward prism sheet, and is supplied to the first prism sheet 104. In the first prism sheet 104, the light refracted and diffused by the second prism sheet is refracted and diffused in the third prism sheet 104 using the principle of the reverse prism sheet, And reaches the inclined surface of the sheet 104, thereby converging the light vertically (4) and emitting the light. Therefore, light passing through the first and second prism sheets 102 and 104 is optimized so that light can be irradiated perpendicularly to a liquid crystal panel not shown.

At this time, the inclined surfaces of the first and second prism sheets 102 and 104 are formed such that the light emitted from the first prism sheet 104 can be vertical. Here, the slopes α and β of the first and second prism sheets 102 and 104 are different from each other. Further, the valleys and the floor of the first and second prism sheets 102 and 104 may be coincident or different from each other.

In the prism sheet 100 according to the embodiment of the present invention, the second prism sheet disperses the light of the light source, thereby preventing a bright line generated in the light-incident portion of the backlight unit using the lamp, It is possible to prevent a hot spot or a color unevenness phenomenon. Further, the first prism sheet is refracted by the second prism sheet and refracts the incident light to vertically condense the light, thereby improving the brightness of the liquid crystal display device.

3 is a diagram illustrating a backlight unit according to an embodiment of the present invention.

Referring to FIG. 3, at least one light source 106, a light source housing 108 for protecting the light source 106, a light guide plate 112 for scattering light incident from the light source 106 and emitting light to the front side, A diffusion sheet 110 for diffusing the light supplied to the light guide plate 112 and a prism sheet for refracting the light supplied from the diffusion sheet 110 100).

At least one light source (106) is arranged to face the light incoming portion of the light guide plate (112). The light source 112 is driven by a light source voltage from the outside to generate light, and irradiates the generated light to the light-incoming portion of the light guide plate 112. The light source 106 may be any one of a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED).

The light source housing 108 is formed to surround the light source. The light source housing 108 protects the light source 106 and reflects the light from the light source 106 and guides the light to the light guide plate 112. At this time, a reflective material capable of reflecting light of the light source 106 may be formed inside the light source housing 108. At this time, the reflective material may be formed by coating or painting any one of Cr, Ag, and Br.

The light guide plate 112 guides the traveling direction of light incident from the light source 106 to the prism sheet 100 through the incident surface. That is, the light guide plate 112 converts the incident light incident from the light source 106 into plane light and irradiates the prism sheet 100 with the light. At this time, the light guide plate 112 may be formed of a plastic material such as PMA (poly methylmethacrylate) or a resin or a heat resistant glass material in a flat type or a wedge type

On the other hand, the light guide plate 112 may be a prism light guide plate having a tilted rear surface and a prism-shaped exit surface having an obtuse and a convex shape formed in a linear or circular shape. That is, a plurality of prism patterns having hills and valleys may be formed on the exit surface of the light guide plate 112.

The reflection plate 114 is disposed on the lower surface of the light guide plate 112 and redirects light incident from the light guide plate 112 toward the light guide plate 112 to reduce light loss.

The diffusion sheet 110 diffuses the light irradiated from the light guide plate 112 to the entire area and irradiates the light onto the prism sheet 100.

The prism sheet 100 is composed of first and second prism sheets, and has the same configuration as the prism sheet according to the embodiment of the present invention shown in FIG.

The first prism sheet 104 is formed to have an acid shape on the first and second surfaces. The first prism sheet 104 refracts light (2) supplied from the second prism sheet 102 (3) and condenses the light vertically () onto a liquid crystal panel (not shown). Here, the first prism sheet 104 may be formed of the same material as or different from the second prism sheet 102. At this time, the first prism sheet 104 is formed of a polycarbonate series or an acrylic resin series.

The second prism sheet 102 is formed to correspond to the shape on either side of the first prism sheet 104. Here, the second prism sheet 102 refracts (not shown) light (1) emitted from the light source (2) and supplies it to the first prism sheet 104. At this time, the second prism sheet 102 is formed of an acryl resin series. Further, the second prism sheet 102 is formed to be equal to or smaller than the refractive index of the first prism sheet 104.

Therefore, by using the refraction diffusion phenomenon which is an advantage of the forward prism sheet and the convergence phenomenon which is an advantage of the reverse prism sheet, the light is condensed in the first prism sheet 104 via the second prism sheet 102, The brightness can be improved by supplying light to the liquid crystal panel (not shown) within a range of 20 to 30 ° with respect to the normal line.

4 is a view illustrating a liquid crystal display device according to an embodiment of the present invention.

4, a liquid crystal display device according to an embodiment of the present invention includes a liquid crystal panel 120 for displaying an image by adjusting a light transmittance, and a backlight unit 200 for irradiating light to the liquid crystal panel 120 .

The liquid crystal panels are composed of a lower substrate and an upper substrate 120, 118 which are bonded to each other and facing each other. At this time, a spacer (not shown) and a liquid crystal layer (not shown) are provided between the lower substrate and the upper substrate 120 to keep the gap therebetween constant.

The upper substrate 120 includes at least three color filters including red, green, and blue, a separation matrix of each color filter, a black matrix defining a pixel cell, and a common electrode to which a common voltage is supplied. Here, the common electrode may be formed on the lower substrate 118 according to the mode of the liquid crystal.

The lower substrate 118 includes a plurality of data lines and a plurality of gate lines formed to intersect with each other, a thin film transistor (TFT) and a thin film transistor (TFT) formed in each pixel cell region defined by intersecting data lines and gate lines And a pixel electrode connected to the TFT. The thin film transistor TFT supplies an image signal from the data line to the liquid crystal cell in response to a gate pulse from the gate line.

Since the liquid crystal cell (not shown) is composed of a common electrode facing the liquid crystal layer and a pixel electrode connected to the thin film transistor (TFT), it can be equivalently expressed by a liquid crystal capacitor. The liquid crystal cell also includes a storage capacitor for holding the image signal charged in the liquid crystal capacitor until the next image signal is charged.

The bottom cover 116 is formed to accommodate the backlight unit 200.

The top cover 112 covers the front edge of the liquid crystal panel disposed on the bottom cover 102 and the side surface of the bottom cover 116. To this end, the top cover 112 is composed of a non-display area excluding the display area of the liquid crystal panel, that is, a flat part covering the edge, and a side part folded vertically from the flat part and wrapping the side surface of the bottom cover 310 .

As a result of the experiment of the liquid crystal display device using the first and second prism sheets 102 and 104, the first and second prism sheets 102 and 104 according to the embodiment of the present invention were used to measure the viewing angle FIG. 5B is a graph showing the brightness of the center portion of the prism sheet according to the embodiment of the present invention by using the first and second prism sheets 102 and 104 according to an embodiment of the present invention. The vertical luminance was 4000 nit in the Polar chart.

It can be confirmed that the luminance improvement and the color unevenness are improved by comparing FIG. 6A showing color unevenness on the conventional liquid crystal panel with FIG. 6B showing the liquid crystal panel using the prism sheet of the present invention.

7 is a view illustrating a method of manufacturing a prism sheet according to an embodiment of the present invention.

Referring to Figure 7, there is shown a method of making a prism sheet 302 comprising the steps of preparing a first prism sheet 302 and passing the first prism sheet 302 through a roller 304a of an acid form 306, Forming a first prism sheet 302a having a first prism sheet 302a and a second prism sheet 314 on one side of the first prism sheet 302a; (312), and curing the second prism sheet (314).

First, a first prism sheet 302 is prepared. At this time, the first prism sheet 302 is formed of a polycarbonate series or an acrylic resin series.

The first prism sheet 302 is then passed through the rollers 304a and 304b of the acid form 306 to form a first prism sheet 302a having first and second surfaces in acid form.

Next, the UV curable resin 310 supplied by the resin feeder 308 is applied to either side of the first prism sheet 302a having the first and second surfaces in an acid form. At this time, the UV curable resin 310 is formed of a polycarbonate series or an acrylic resin series.

Next, the UV curable resin 310 applied to the first prism sheet 302a is planarized using a roller 312. Then,

Then, the planarized UV curable resin 310 is cured by a UV curing unit 316 to form a second prism sheet 314. [

8 is a view showing another method of manufacturing a prism sheet according to an embodiment of the present invention.

8, there is provided a method of manufacturing a semiconductor device, comprising the steps of preparing a base film 402, applying a UV curable resin 406 to a first surface of a base film 402, Forming a first prism sheet (406a) having an acid shape on a first surface by passing the first prism sheet (406a) through the first prism sheet (408); curing a first prism sheet (406a) Curing the UV-curable resin 408 on the first prism sheet 406a having an acid form to form a second prism sheet 406a by curing the UV-curable resin 408 on the first prism sheet 406a, (418) is applied to the second surface of the base film (402), and the UV curable resin (418) is applied to the second surface of the base film Passing through a roller (420) to form a first prism sheet (418a) having an acid shape on a second surface of the base film It is configured to include a first step of curing a first prism sheet (418a) having an acid form to a second surface of the film device (402).

The base film 402 is moved using the first and second rollers 420a and 420b and the UV curable resin 406 supplied through the first resin feeder 404 is supplied to the first Lt; / RTI > At this time, the UV curing resin 406 is formed of a polycarbonate series or an acrylic resin series.

The UV curable resin 406 applied to the first side of the base film 402 is then passed through the roller 408 in the form of an acid to form the first side of the base film 402 to have an acid form.

Then, the UV curable resin 406 having an acid form formed on the first surface of the base film 204 is cured by using the first UV curing unit 412 to form a first prism sheet 406a ).

The first surface moving between the third and fourth rollers 420c and 420d is then irradiated with UV curable resin 408 supplied through the second resin feeder 410b onto the first prism sheet 406a in the form of an acid, ).

Next, the UV curable resin 408 formed on the first prism sheet 406a is cured by using the second UV curing unit 414 to form the second prism sheet 408a.

Next, the second film is rotated by using the third to fifth rollers 420e, 420f, and 420g so that the second side of the base film faces upward.

Then, the UV curable resin 418 supplied through the third resin feeder 416 is applied to the second surface of the base film.

Then, a roller 420 in the form of an acid is passed through the second surface of the base film coated with the UV curable resin 418 to form a UV curable resin having an acid form on the second surface.

Next, the UV curable resin 418 having an acid form formed on the second surface of the base film 204 is cured by using the third UV curing apparatus 420 to form a second prism sheet 418a ).

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Will be clear to those who have knowledge of.

1A and 1B show a conventional prism sheet.

2 illustrates a prism sheet according to an embodiment of the present invention.

3 illustrates a backlight unit using a prism sheet according to an embodiment of the present invention.

4 is a view illustrating a liquid crystal display device using a prism sheet according to an embodiment of the present invention.

5A and 5B are diagrams showing the results of measurement of viewing angle and luminance according to the present invention.

6A and 6B are diagrams showing improvement of the color unevenness in the conventional and the liquid crystal display device of the present invention.

7 is a view illustrating a manufacturing process of a prism sheet according to an embodiment of the present invention.

7 is a view illustrating a manufacturing process of a prism sheet according to another embodiment of the present invention.

Description of the Related Art

100: prism sheet 102: second prism sheet

104: first prism sheet

Claims (27)

A first prism sheet having an acid (?) Shape on the upper surface and the lower surface; And a second prism sheet having the same refractive index as the first prism sheet and having an upper surface formed along a lower surface of the first prism sheet, Wherein an inclination of the upper surface of the first prism sheet and an upper surface of the second prism sheet are different from each other. delete The method according to claim 1, Wherein the first and second prism sheets are formed of the same material. The method of claim 3, Wherein the first and second prism sheets are made of acryl resin. delete delete The method according to claim 1, And the valleys and the valleys of the first and second prism sheets coincide with each other. The method according to claim 1, And the valleys of the first and second prism sheets are different from each other. A light source; A light guide plate for scattering light incident from the light source and emitting the light to the front side; And a prism sheet according to any one of claims 1, 3, 4, 7, and 8 for refracting light emitted from the light guide plate. 10. The method of claim 9, Wherein the light source comprises any one of a cold cathode fluorescent lamp (CCFL), a hot cathode fluorescent lamp (HCFL), an external electrode fluorescent lamp (EEFL), and a light emitting diode (LED). A liquid crystal panel for displaying an image by adjusting a light transmittance; And A liquid crystal display device comprising the backlight unit according to claim 10 for emitting light to the liquid crystal panel. Rotating an acid (DELTA) shaped roller at the top and bottom of the first prism sheet to form an acid shape on the top and bottom surfaces of the first prism sheet; Applying a UV curable resin having the same refractive index as the first prism sheet to the lower surface of the first prism sheet; Planarizing the applied UV curable resin using a roller; And Curing the UV curable resin to form a second prism sheet having a top surface formed along the bottom surface of the first prism sheet, Wherein an inclination degree of the upper surface of the first prism sheet and an upper surface of the second prism sheet are different from each other. delete 13. The method of claim 12, Wherein the first and second prism sheets are formed of the same material. 15. The method of claim 14, Wherein the first and second prism sheets are formed of an acryl resin series. delete delete 13. The method of claim 12, And the valleys and the floor of the first and second prism sheets coincide with each other. 13. The method of claim 12, And the valleys of the first and second prism sheets are different from each other. Preparing a base film; Applying a first UV curable resin to the entire surface of the base film; Passing the first UV curable resin through a roller in the form of an acid (?) To form a surface of the first UV curable resin in an acid form; Curing the first UV curable resin; Forming a second UV curable resin on the first UV curable resin; Curing the second UV curable resin to form a second prism sheet having a top surface formed along the acid form of the first UV curable resin; Applying a third UV curable resin to the back side of the base film; Passing the third UV curable resin through an acid type roller to form a surface of the third UV curable resin in an acid form; And Curing the third UV curable resin to form a first prism sheet having an acidic top surface of the third UV curable resin and an acidic bottom surface of the first UV curable resin, Wherein the refractive index of the second prism sheet is equal to the refractive index of the first prism sheet and the inclination of the upper surface of the first prism sheet and the upper surface of the second prism sheet are different. delete 21. The method of claim 20, Wherein the first and second prism sheets are formed of the same material. 23. The method of claim 22, Wherein the first and second prism sheets are formed of an acryl resin series. delete delete 21. The method of claim 20, And the valleys and the floor of the first and second prism sheets coincide with each other. 21. The method of claim 20, And the valleys of the first and second prism sheets are different from each other.

Images