KR101288594B1 - Optical fiber type light guide plate and backlight unit using the same - Google Patents

Abstract

There is provided a light guide plate of an optical fiber type and a backlight unit having the same, which can easily control the amount of light emitted along the longitudinal direction of the optical fiber and improve flatness. The light guide plate of the optical fiber type includes a core and a plurality of optical fiber bundles including a cladding formed of a light guide portion having a smaller refractive index than the core and a light emitting portion having a larger refractive index than or equal to the core. These are the plates listed in parallel.

Backlight Unit, Optical Fiber, Light Guide Plate

Description

Optical fiber type light guide plate and backlight unit using the same}

1 is a block diagram showing a conventional optical fiber.

2 is a configuration diagram of a backlight unit having a conventional optical fiber.

3 is a schematic cross-sectional view of a backlight unit according to an embodiment of the present invention.

4 is a perspective view of an optical fiber constituting the light guide plate of FIG. 3.

FIG. 5 is a cross-sectional view illustrating lines II and II of FIG. 4.

6 to 12 are views for explaining various modified structures of the optical fiber shown in FIG.

DESCRIPTION OF THE REFERENCE NUMERALS (S)

210: light source 100: light guide plate of optical fiber type

101: optical fiber 110: core

120: clad 121: light guide portion

122: light diverging unit 220: reflective sheet

230: optical sheet

The present invention relates to a backlight unit using an optical fiber, and more particularly, to a light guide plate of an optical fiber type and a backlight unit having the same.

Optical fiber (Fiber optics) is a thin, flexible fiber made of thin, long pulled transparent dielectrics (insulators), such as quartz glass or plastic, which allows light to pass through its center and does not leak light when bent slightly. The light is propagated to a long distance without attenuation.

As the optical fiber, light incident on the core is made to be slightly smaller than the refractive index of the core and clad optical fiber, that is, a cladding layer that prevents light from going out than the refractive index of the core, which is a core part passing through the light. Optical fibers that propagate while repeating total reflection at the interface between the core and the clad with different refractive indices are mainly used.

On the other hand, a flexible display device having a display surface that can be bent is a reflective display method that displays an image by reflecting ambient light without a backlight unit, which is a self-luminous source. The introduction of a display method that includes an in-backlight unit and can display an image regardless of surrounding conditions is under consideration.

Optical fiber is mainly used in the field of communication and sensors, but due to its thin and flexible characteristics, it is expected to have various strengths when applied to a backlight unit of a flexible display device.

1 is a block diagram showing a conventional optical fiber, Figure 2 is a block diagram of a backlight unit having a conventional optical fiber.

Referring to FIG. 1, light generated from a light source (not shown) is collected by the light collecting unit 10 and is incident into the optical fiber 20, and the incident light is totally reflected inside the optical fiber 20 and proceeds to the optical fiber ( 20) is bent more than a certain angle and exits outside where the critical angle condition of total reflection is broken. Fill threads are disposed at portions where the optical fiber 20 is bent for a flat structure.

FIG. 2 is a light source 50, a light collecting unit 10, and a bundle using a plurality of optical fibers 20 of the configuration as shown in FIG. 1 to produce a planar light, the reflecting plate 40 and several optical sheets 41, 42, 43 ) Shows a backlight unit constructed by combining.

However, in such a structure, the optical fiber 20 must be partially bent so as to be out of the total reflection condition in order to emit light traveling through the inside of the optical fiber 20 to the outside.

At this time, it is difficult to constantly control the degree of bending of the optical fiber 20, the bundle of the optical fiber 20 by the bending of the optical fiber 20 does not have a flat overall, has a constant thickness. In addition, in order to eliminate the light loss, a length greater than or equal to a predetermined value is required for the connection portion between the incident surface of the optical fiber 20 bundle and the light source 50.

These issues have a problem of forming a backlight unit applicable to a thin and highly efficient backlight unit and a flexible display device that can be folded or rolled using the optical fiber 20.

Accordingly, an object of the present invention is to provide a light guide plate of an optical fiber type and a backlight unit having the same, which can easily control the amount of light emitted along the longitudinal direction of the optical fiber and improve flatness.

Another object of the present invention is to provide a light guide plate having a thin, highly efficient optical fiber type, and a backlight unit having the same.

Another object of the present invention is to provide a light guide plate of a flexible optical fiber type that can be applied to a flexible display device and a backlight unit having the same.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise forms disclosed. Other objects, which will be apparent to those skilled in the art, It will be possible.

The optical guide plate of the optical fiber type according to the present invention for achieving the above technical problem surrounds a core and an outer circumferential surface of the core, and a light guide portion having a smaller refractive index than the core and a light having a greater refractive index than the core. A plurality of optical fiber bundles including a clad made up of diverging parts are plate bodies arranged in parallel.

The backlight unit according to the present invention comprises a light source for generating light and a plurality of optical fibers each having a core and a clad surrounding the outer circumferential surface of the core, the backlight unit being disposed on the side of the light source, A light guide plate of an optical fiber type for converting the emitted light into planar light and emitting the light to the front, a reflective sheet positioned at the bottom of the light guide plate to reflect the light toward the back, and at least one optical sheet positioned at the top of the light guide plate. Include.

The details of other embodiments are included in the detailed description and drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. Like reference numerals refer to like elements throughout.

Hereinafter, a light guide plate of an optical fiber type and a backlight unit having the same according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a schematic cross-sectional view of a backlight unit according to an embodiment of the present invention.

Referring to FIG. 3, a backlight unit according to an exemplary embodiment of the present invention may include a light source 210 for generating light and an optical fiber type for providing light generated from the light source 210 to a display panel (not shown). The light guide plate 100 is disposed at the rear of the light guide plate 100 to reflect the light generated from the light source 210 to the light guide plate 100 so as to improve the efficiency of light, disposed on the front surface of the light guide plate 100. And a plurality of optical sheets 230 for diffusing and condensing light emitted from the light guide plate 100.

The light source 210 is a light source in the form of a line light source disposed on one or both sides of the light guide plate 100 to emit light, and includes a light emitting diode array (LED Array) and a cold cathode fluorescent lamp (CCFL). Fluorescent Lamp) and External Electrode Fluorescent Lamp (EEFL) are used.

The light emitted from the light source 210 is directly incident into the light guide plate 100 of the optical fiber type, or reflected by a lamp housing (not shown) surrounding a part of the light source 210 and then into the light guide plate 100. Incident.

The light guide plate 100 of the optical fiber type is disposed on the side of the light source 210 and guides the light emitted from the light source 210 to the plane and converts the light into planar light and emits the converted light to the front.

The optical sheet 230 and the reflective sheet 220 are for obtaining uniformly emitted light distribution characteristics in the light exit surface of the light guide plate 100 made of the optical fiber bundle.

The reflective sheet 220 is located under the optical guide plate 100 of the optical fiber type and reflects the light toward the rear of the light guide plate 100 back to the front to increase the efficiency of the light.

As the optical sheet 230, diffusion sheets 231 and 234 for diffusing light and prism sheets 232 and 233 for condensing light are used, and two diffusion sheets 231 and 234 are disposed at the top and the bottom. It is possible to adopt a structure in which two prism sheets 232 and 233 are placed therebetween.

In this structure, the lowermost diffusion sheet 231 uniformly distributes the light incident from the light guide plate 100 to prevent the light from being partially condensed, and the two prism sheets 232 and 233 have a lower diffusion. The light diffused by the sheet 231 is collected to increase the front luminance of the light provided to the display panel (not shown).

The two prism sheets 232 and 233 are unilaterally formed with a plurality of triangular prisms on each upper surface, and the directions of the prisms formed on the prism sheets 232 and 233 are each other on a plane parallel to the display panel (not shown). It is provided orthogonally.

The top diffusion sheet 234 protects the surfaces of the prism sheets 232 and 233, and the two prism sheets 232 and 233 in order to improve the brightness for each viewing angle degraded by the condensing characteristics of the prism sheets 232 and 233. ) Diffuses the collected light.

All four optical sheets 230 need not be provided in the backlight unit, and may be selectively applied according to the structure of the backlight unit or the type of display panel.

Conventional light guide plate should be formed to have a thickness (for example, 0.5mm to 10mm) or more in a flexible material such as a transparent plastic material, while the light guide plate 100 of the optical fiber type has flexibility, relatively without bending The light emitted from the light source 210 can be converted into planar light with only a thin thickness (for example, 0.5 mm or less).

Therefore, the flexible display may be easily implemented using the backlight unit provided with the optical fiber type light guide plate 100, the flexible optical sheet 230, the reflective sheet 220, and the like.

FIG. 4 is a perspective view of an optical fiber constituting the light guide plate of FIG. 3, and FIG. 5 is a cross-sectional view illustrating lines II and II of FIG. 4.

The light guide plate 100 of the optical fiber type is configured such that the optical fiber bundles composed of a plurality of optical fibers 101 are arranged in parallel to form a plate.

Each optical fiber 101 constituting the light guide plate 100 is composed of a core 110 at the center and a clad 120 surrounding the outer circumferential surface of the core.

The clad 120 has a smaller refractive index n 2 than the refractive index n 1 of the core 110, so that the light guide 121 and the core 110 have a larger refractive index n 3 than or equal to the refractive index n 1 of the core 110. It consists of a light diverging unit 122 to be emitted to the outside.

Here, the refractive index n1 of the core 110, the light guide portion 121 of the clad 120 and the refractive indexes n2 and n3 of the light diverging portion 122 have values of about 1.2 to 1.6 which are larger than the refractive index of air. .

That is, the light emitted from the light source 210 is totally internally reflected through the core 110 of the optical fiber 101 and proceeds, so that the light passing through the core is partially emitted to the outside of the optical fiber 101 at an arbitrary position. The refractive index of the cladding 120 surrounding the 110 is configured differently at a predetermined position, that is, the light diverging portion 122.

When the refractive index of the clad 120 is smaller than the refractive index of the core 110 in the optical fiber 101, the light inside the core 110 may travel in total reflection. However, when the refractive index of the clad 120 is greater than the core 110 at any position, the total reflection condition is broken so that a part of the light traveling inside the core 110 may escape to the outside of the optical fiber 101.

The light guide portion 121 and the light diverging portion 122 are configured to contact the inner surface of the clad 120 from the outermost layer of the clad 120.

When the optical fiber 101 having such a structure is bundled into two or more strands to form a light guide plate 100 of an optical fiber type, and light is incident on one side or both sides of the light guide plate 100, the optical fiber 101 may be formed in an arbitrary length direction of the optical fiber 101. The backlight unit may be configured to emit light at a position.

In addition, as shown in FIGS. 4 and 5, when the light diverging part 122 is formed to surround the entire outer surface of the core 110, since the light traveling in the core 110 may be emitted to both the upper and lower parts. The structure of the optical fiber 101 can be effectively employed for a double-sided display.

On the other hand, in the optical fiber type light guide plate 100, the amount of light incident from the light source 210 and exiting the front surface of the light guide plate 100 is the structure of the optical fiber 101, that is, the area, the length, It may be adjusted differently by the position, the distance between the adjacent light emitting portion 122, and the like.

6 to 12 are views for explaining various modified structures of the optical fiber shown in FIG.

In the case of FIG. 5, the light diverging part 122 of the clad 120 is formed to surround the entire outer circumferential surface of the core 110 in a predetermined region. On the other hand, referring to FIG. 6, the light diverging part 122 of the clad 120 is formed only on a part of the outer circumferential surface (upper side) in a predetermined region of the core 110.

5 and 6, when the refractive indices of the core 110, the light guide portion 121 of the clad 120, and the light diverging portion 122 are n1, n2, n3, the refractive index characteristics of the optical fiber 101 are represented. The mathematical expression is as follows.

n3 ≥ n1> n2

Referring to FIG. 7, a plurality of light diverging parts 122 of the clad 120 are formed on a part of an outer circumferential surface of a predetermined region of the core 110, and the refractive indices are all the same, but are formed to have different lengths for each position.

FIG. 8 illustrates a case in which the light diverging part 122 of the clad 120 is formed over the entire outer circumferential surface within a predetermined region of the core 110.

The refractive index characteristics of FIGS. 7 and 8 are the same as Equation 1, and the length characteristics are the same as Equation 2.

a ≠ b ≠ c

9 and 10, the clad 120 includes a plurality of light diverging parts 122 having the same refractive index and the same length. FIG. 9 illustrates a case in which the light diverging portion 122 of the clad 120 is formed only on a part of the outer circumferential surface in a predetermined region, and FIG.

The refractive index characteristics of FIGS. 9 and 10 are also the same as in Equation 1, and the length characteristic is as in Equation 3.

l ≠ m ≠ n

11 and 12, in the clad 120, a plurality of light diverging parts 122 having different refractive indices and the same length are formed at regular intervals.

FIG. 11 illustrates a case in which each of the light diverters 122 is formed only on a part of the outer circumferential surface in a predetermined region, and FIG. 12 illustrates a case in which the light diverters 122 are formed on the entire outer circumferential surface of the predetermined region.

The refractive index characteristics of FIGS. 11 and 12 are shown in Equation 4.

n3 ≠ n4 ≠ n5 ≠ n6 ≥ n1> n2

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand.

Therefore, it should be understood that the above-described embodiments are provided so that those skilled in the art can fully understand the scope of the present invention. Therefore, it should be understood that the embodiments are to be considered in all respects as illustrative and not restrictive, The invention is only defined by the scope of the claims.

The light guide plate of the optical fiber type and the backlight unit having the same according to the present invention made as described above can easily control the amount of light emitted along the longitudinal direction of the optical fiber and improve flatness.

In addition, the light guide plate of the optical fiber type and the backlight unit having the same according to the present invention are thin and have high efficiency, and thus can be easily applied to a flexible display device.

Claims (19)

Core; And Clad covering the outer circumferential surface of the core, consisting of a light guide portion having a smaller refractive index than the core and a light diverging portion having a larger refractive index than or equal to the core. A plurality of optical fiber bundles including a parallel to form a plate body, the light inside the core proceeds to form a total reflection in the light guide portion, a portion of the light from the light emitting portion is emitted to the outside of the core The cladding has a plurality of refractive indices, and the refractive index of the light emitting portion is greater than the refractive index of the light guide portion, and the light emitted to the outside of the core is controlled by at least one of an area, a length, a position, and an interval of the light emitting portion. Light guide plate of the optical fiber type, characterized in that the. The method of claim 1, The light emitting part of the optical fiber type, characterized in that formed in a portion of the outer peripheral surface of the core within a predetermined region. The method of claim 1, The light emitting part of the optical fiber type, characterized in that formed in the predetermined area to surround the entire outer peripheral surface of the core. The method of claim 1, The light emitting part of the optical fiber type, characterized in that formed in a plurality of pieces having a different length for each position. The method of claim 1, The light guiding plate of the optical fiber type, characterized in that a plurality of light emitting portions are formed at regular intervals. The method of claim 1, The light emitting part of the optical fiber type, characterized in that the plurality of light diverging portion is formed to have a different refractive index. Core; And Clad covering the outer circumferential surface of the core, consisting of a light guide portion having a smaller refractive index than the core and a light diverging portion having a larger refractive index than or equal to the core. Includes, the light inside the core proceeds to form a total reflection in the light guide portion, a portion of the light from the light emitting portion is emitted to the outside of the core, the clad has a plurality of refractive index, the light divergence The negative refractive index is greater than the refractive index of the light guide portion, the light emitted to the outside of the core is controlled by at least one of the area, length, position, interval of the light diverging portion. A light source for generating light; An optical fiber type, each of which is composed of a plurality of optical fibers having a core and a clad that surrounds an outer circumferential surface of the core, is disposed on the side of the light source, and converts light emitted from the light source into planar light and exits to the front. Light guide plate; A reflection sheet positioned below the light guide plate to reflect light toward the rear in front; And One or more optical sheets positioned on the light guide plate Including, The light guide plate of the optical fiber type includes a light guide portion having a smaller refractive index than the core and a light diverging portion having a refractive index greater than or equal to that of the core, and the light inside the core is totally reflected by the light guide portion. And a part of light is emitted to the outside of the core in the light emitting part, the clad has a plurality of refractive indices, and the refractive index of the light emitting part is greater than the refractive index of the light guide part and is emitted to the outside of the core. The light unit is controlled by at least one of the area, length, position, interval of the light diverging portion. delete Claim 10 has been abandoned due to the setting registration fee. 9. The method of claim 8, The light emitting unit is a backlight unit, characterized in that formed in a portion of the outer peripheral surface of the core within a predetermined area. Claim 11 was abandoned when the registration fee was paid. 9. The method of claim 8, The light emitting unit is a backlight unit, characterized in that formed in the entire outer peripheral surface of the core within a predetermined region. Claim 12 is abandoned in setting registration fee. 9. The method of claim 8, The light emitting unit is a backlight unit, characterized in that formed in plurality having a different length for each position. Claim 13 was abandoned upon payment of a registration fee. 9. The method of claim 8, The light emitting unit, the backlight unit, characterized in that a plurality of formed at regular intervals. Claim 14 has been abandoned due to the setting registration fee. 9. The method of claim 8, The light emitting unit is a backlight unit, characterized in that formed in a plurality of different refractive index. Claim 15 is abandoned in the setting registration fee payment. 9. The method of claim 8, And an amount of light incident from the light source and output to the front surface of the light guide plate is differently controlled by an area, a length, a position of the light emitting part, and a distance between the light emitting parts. 9. The method of claim 8, The light emitting unit is in contact with the inner surface of the cladding from the outermost layer of the cladding unit. Claim 17 has been abandoned due to the setting registration fee. 9. The method of claim 8, The light source may be any one of a light emitting diode array (LED array), a cold cathode fluorescent lamp (CCFL), and an external electrode fluorescent lamp (EEFL). Claim 18 has been abandoned due to the setting registration fee. 9. The method of claim 8, The optical sheet, A diffusion sheet for uniformly diffusing light from the light guide plate of the optical fiber type; And Prism sheet for collecting light incident from the diffusion sheet . 9. The method of claim 8, The light guide plate of the optical fiber type is flexible.

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