Backlight having all-in-one type light guide plate and method of ...

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BACKLIGHT HAVING ALL-IN-ONE TYPE
LIGHT GUIDE PLATE AND METHOD OF
MANUFACTURING ALL-IN-ONE TYPE
LIGHT GUIDE PLATE

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CROSS-REFERENCE TO RELATED PATENT
APPLICATIONS

This application claims the benefit of Korean Patent Application Nos. 10-2006-0028028, filed on Mar. 28, 2006, and 10 10-2007-0002647, filed on Jan. 9, 2007, in the Korean Intellectual Property Office, the disclosures of which are incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION 15

1. Field of the Invention

Apparatuses and methods consistent with the present invention relate to a backlight and a method of manufacturing a light guide plate, and more particularly, to a backlight hav- 20 ing an all-in-one type light guide plate and a method of manufacturing the all-in-one type light guide plate.

2. Description of the Related Art

Typically, backlights are used to illuminate flat displays, for example, liquid crystal displays, and are mainly classified 25 as direct light emitting type backlights or light guide plate type backlights depending on the positions of the light sources. Light guide plate type backlights may be also classified as flat type backlights or wedge type backlights.

In direct light emitting type backlights, a light source is 30 installed close below a light exit surface, thereby enabling a surface light emission. Advantageously, direct light emitting type backlights include more light sources in comparison with light guide plate type backlights, thus increasing light brightness and widening the light exit surface. However, in 35 direct light emitting type backlights, power consumption is higher because many light sources are used. Also, it is difficult to realize thin film direct light emitting type backlights because the shape of light sources is reflected, and thus light uniformity is severely reduced. 40

In light guide plate type backlights, a light guide plate is employed to guide light to a light exit surface. Light sources are disposed on a side surface of the light guide plate. The number of light sources is limited according to a length of a side surface of the light guide plate. Advantageously, thin film 45 light guide plate type backlights can be realized easily. On the other hand, a process for making light brightness uniform on the entire light exit surface is complicated in comparison with direct light emitting type backlights.

Flat type backlights are used in monitors or when high- 50 brightness is required. In flat type backlights, the light sources may be fixed to two or all four edges of the light guide plate. To increase light brightness when a plurality of light sources are used, an edge thickness of the light guide plate should be uniform. 55

Wedge type backlights are used in devices, such as notebook computers, in which it is difficult to use several light sources due to limited power resources. Only one surface constituting a light incident portion is widened and other surface is narrowed, to thereby reduce the weight of the 60 backlight.

Light sources used in light guide plate type backlights may be line light-sources and point light-sources. A cold cathode fluorescent lamp (CCFL) may be used as a line light-source. In this case, electrodes at both ends of the CCFL are installed 65 within a pipe. A light emitting diode (LED) may be used a point light-source. Advantageously, the CCFL emits strong

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white light having high-brightness and high-uniformity, and allows design enlargement. However, the CCFL is operated via a high frequency alternating current (AC) signal and at a narrow range of an operation temperature. Meanwhile, the performance of the LED is inferior to that of the CCFL in view of light brightness and uniformity. However, the LED has advantages of operating via a direct current (DC) signal and at a wide range of operation temperatures. In addition, LEDs have long lifespans and can be used to make a thin film direct light emitting type backlight.

FIG. 1 is a sectional view schematically illustrating a conventional side emitting type backlight.

Referring to FIG. 1, line light-sources 10 are installed at both sides 21 and 22 of a light guide plate 20. A light path converter 23 is formed on a lower surface of the light guide plate 20 to guide light incident from the line light-sources 10.

A plurality of prisms or prism-shaped structures 30 are formed on an upper side of the light guide plate 20 to diffuse the light coming out from an exit surface 24 into the upper side of the light guide plate 20. The prism-shaped structures 30 are fixed to the upper side of the light guide plate 20 by an adhesive layer 31.

The light incident from the line light-sources 10 into the light guide plate 20 is guided to the exit surface 24 of the light guide plate 20 by the light path converter 23. The light passes through an adhesive layer 31 and diffuses to the upper side of the light guide plate 20 through the prism-shaped structures 30.

Since the prism-shaped structures 30 are fixed to the upper side of the light guide plate 20 by the adhesive layer 31, the light incident into prism-shaped structures 30 must pass through the adhesive layer 31. Thus, the adhesive layer 31 affects the transmission of light. In particular, since the backlight performance depends on an adhering degree of the adhesive force, the adhesive layer 31 should be removed to increase the backlight performance.

SUMMARY OF THE INVENTION

Exemplary embodiments of the present invention provide an all-in-one type light guide plate having improved performance by integrally forming a prism-shaped structure thereon, a backlight having the all-in-one type light guide plate, and a method of manufacturing the all-in-one type light guide plate.

According to an aspect of the present invention, there is provided an all-in-one type light guide plate including a plurality of prism-shaped structures which are integrally formed thereon and which reflect light incident form a light source to be emitted from the light guide plate.

The prism-shaped structures may be formed so that a width of an upper surface through which light is emitted is greater than a width of a lower region thereof.

A plurality of diffusers which diffuse light may be integrally formed on the upper surfaces of the prism-shaped structures.

According to another aspect of the present invention, there is provided a backlight including: a light source; and an all-in-one type light guide plate including a plurality of prism-shaped structures integrally formed thereon, wherein the prism-shaped structures reflect light incident form a light source to be emitted from the light guide plate.

Each of the prism-shaped structures may be formed so that a width of an upper surface through which light is emitted is greater than a width of a lower region thereof.

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A plurality of diffusers which diffuse light may be integrally formed on the upper surface of the prism-shaped structures.

According to another aspect of the present invention, there is provided a method of manufacturing an all-in-one type light guide plate including a plurality of prism-shaped structures that are integrally formed on the light guide plate and which reflect light, the method including: forming a sacrificial layer on a substrate; etching the sacrificial layer to form a plurality of prism-shaped structures on the sacrificial layer; forming an all-in-one type light guide plate by coating an elastic material on the sacrificial layer and the prism-shaped structures; and separating the all-in-one type light guide plate from the sacrificial layer.

The etching of the sacrificial layer on the substrate may include regulating a thickness of the sacrificial layer so that a width of an upper, light exit surface of each of the prismshaped structures is larger than a width of a lower, light entry region of the prism-shaped structures.

The etching of the sacrificial layer may also include partially filing an etched portion of the sacrificial layer with a filler to adjust a thickness of the prism-shaped structures.

The etching of the sacrificial layer may further include positioning a mask having a plurality of through-holes patterned in a predetermined pattern on the sacrificial layer, and irradiating UV light through the through-holes so that the prism-shaped structures formed have oval cross-sections, or have trapezoidal cross-sections.

The method may further include forming a plurality of diffusers on the substrate prior to forming the sacrificial layer on the substrate.

The sacrificial layer may include a hardening material, and the all-in-one type light guide plate may comprise an elastic material.

The sacrificial layer and the all-in-one type light guide plate may each include an elastic material.

The sacrificial layer may include an elastic material, and the all-in-one type light guide plate may comprise a hardening material.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects and advantages of the present invention will become more apparent by the following detailed description of exemplary embodiments thereof with reference to the attached drawings in which:

FIG. 1 is a sectional view schematically illustrating a conventional side emitting type backlight;

FIG. 2 is a sectional view illustrating a backlight having an all-in-one type light guide plate according to an exemplary embodiment of the present invention;

FIG. 3 is a sectional view illustrating a backlight having an all-in-one type light guide plate according to another exemplary embodiment of the present invention;

FIGS. 4A through 4F are sectional views for illustrating a method of manufacturing an all-in-one type light guide plate according to an exemplary embodiment of the present invention;

FIG. 5 is a sectional view for illustrating a method of irradiating ultraviolet (UV) light on a sacrificial layer so as to form a prism, according to an exemplary embodiment of the present invention; and

FIG. 6 is a sectional view for illustrating a method of adjusting a thickness of the prism of FIG. 5, according to an exemplary embodiment of the present invention

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DETAILED DESCRIPTION OF EXEMPLARY
EMBODIMENTS OF THE INVENTION

The present invention will now be described more fully

5 with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are

10 provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art.

Referring to FIG. 2, a backlight 100 according to an embodiment of the present invention includes a light source

15 110 emitting light and an all-in-one type light guide plate 120. The light source 110 is formed on a side surface 122 of the all-in-one type light guide plate 120, but the present invention is not limited thereto. That is, the light source 110 may be formed on any one of the four surfaces of the all-in-one type

20 light guide plate 120.

The all-in-one type light guide plate 120 includes a light path converter 123 which is formed on a lower surface of a light guide plate 121, and a plurality of prisms or prismshaped structures 124 which totally reflect light to be emitted

25 upwards, are integrally formed on a upper surface of the light guide plate 121. A longitudinal section of the prism-shaped structures 124 has a partially oval shape. A plurality of diffusers 125, which diffuse the light coming out from the prismshaped structures 124, are integrally formed on light exit

30 surfaces 1242 of the prism-shaped structures 124. Accordingly, the light emitted from the light source 110 is incident into the light guide plate 121, is directed to the prism-shaped structures 124 by the light path converter 123, passes through the prism-shaped structures 124, and is diffused finely by the

35 diffusers 125.

The prism-shaped structures 124 include lower light entry regions 1241 onto which the light is incident, and upper light exit surfaces 1242. A width Wl ofthe lower regions 1241 may be smaller than a width W2 of the upper surfaces 1242. A

40 method of forming the prism-shaped structures 124 will be described later.

The light source 110 is formed on one side surface 122 of the light guide plate 121. The light emitted from the light source 110 is incident onto the light guide plate 121 through

45 the one side surface 122 of the light guide plate 121.

Referring to FIG. 3, a backlight 200 according to another embodiment of the present invention includes a light source 210 which emits light, and an all-in-one type light guide plate 220.

50 The light source 210 is formed on one side surface 222 of the all-in-one type light guide plate 220, but a position of the light source 210 innot limited thereto. That is, the light source 210 may be formed on at any one of the four surfaces of the all-in-one type light guide plate 220.

55 The all-in-one type light guide plate 220 includes a light path converter 223 which is formed on a lower surface of a light guide plate 221, and a plurality of prism-shaped structures 224 which totally reflect light to be emitted upwards, and are integrally formed on a upper surface of the light guide

60 plate 221. The prism-shaped structures 224 may have a trapezoidal longitudinal section, unlike the prism-shaped structures 124 illustrated in FIG. 2. A plurality of diffusers 225, which further diffuse the light coming out from the prismshaped structures 224, are integrally formed on each upper

65 surface 2242 of the prism-shaped structures 224. Accordingly, when the light source 210 emits light, the light is incident onto the light guide plate 221, is directed to the