KR20110074148A - Direct type backlight unit - Google Patents

Abstract

PURPOSE: A direct type backlight unit is provided to uniformly emit light by penetrating the light into a light transmission plate. CONSTITUTION: A plurality of LEDs(200) are arranged in a light transmission plate(100). The light transmission plate comprises a plurality of openings(110). A reflector(300) is placed on the lower part of the light transmission plate by being isolated with the light transmission plate. Light from the KEDs is reflected by the reflector and the reflected light is emitted to the upper part through the light transmission plate. The reflected light is emitted to the upper part of the light transmission plate through the openings and the light transmission plate in which the openings are not formed.

Description

Direct type backlight unit

The present invention relates to a direct type backlight unit capable of improving the uniformity of emitted light.

Recently, with the rapid development of the information society, the necessity of a flat panel display device having excellent characteristics such as thinness, light weight, and low power consumption has emerged. Among these, liquid crystal display devices are excellent in resolution, color display, image quality, and so on. It is actively applied to monitors.

In general, a liquid crystal display device is formed by arranging two substrates on which electric field generating electrodes are formed so that the surfaces on which two electrodes are formed face each other, injecting a liquid crystal material between the two substrates, and then applying a voltage to the two electrodes. By moving the liquid crystal molecules by an electric field, the device expresses an image by the transmittance of light that varies accordingly.

However, the liquid crystal display does not emit light by itself and merely controls a light transmittance, and thus requires a separate light source.

Therefore, an image is displayed by arranging a backlight on the back of the liquid crystal panel and injecting light from the backlight into the liquid crystal panel to adjust the amount of light according to the arrangement of the liquid crystals.

Such a backlight is divided into a direct method of directly dimming the entire surface of the substrate by placing a light source on the bottom of the liquid crystal panel and an edge method of reflecting and diffusing light by a light guide plate and a reflecting plate by placing the light source on one side or both sides of the liquid crystal panel.

The direct method requires no light guide plate because light emitted from the lamp is directly emitted to the front of the liquid crystal panel, whereas the edge method requires a light guide plate for emitting light emitted from the side lamp to the front of the backlight.

This invention solves the subject which can improve the uniformity of the emitted light.

The present invention,

A plurality of light emitting diodes;

A light transmissive plate in which the plurality of light emitting diodes are arranged and in which a plurality of openings are formed;

Provided is a direct type backlight unit including a reflector positioned below the light transmissive plate and spaced apart from the light transmissive plate.

The present invention,

A plurality of light emitting diodes;

A light transmitting plate on which the plurality of light emitting diodes are arranged;

A reflection coating film formed on a surface of the light transmissive plate in which the plurality of light emitting diodes are present and having a plurality of openings;

Provided is a direct type backlight unit including a reflector positioned below the light transmissive plate and spaced apart from the light transmissive plate.

In the direct type backlight unit of the present invention, light having a large light intensity is emitted through a light transmissive plate region proximate to each of the plurality of light emitting diodes, and light having a relatively small light intensity is emitted through openings, thereby making it possible to obtain a hot spot. There is an effect that can eliminate the spot and improve the uniformity of the emitted light.

In addition, the direct type backlight unit of the present invention reflects the light emitted from the light emitting diodes to the reflector and transmits the light transmissive plate, so that the path of the light is long, and thus the light can be uniformly emitted.

In addition, in the direct type backlight unit of the present invention, the light emitted from the light emitting diode is reflected between the reflector and the reflective coating film, so that the path is elongated and is emitted to the upper portion of the light transmissive plate through the openings to uniformly emit light. There is.

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

1 is a schematic configuration diagram of a direct type backlight unit according to a first embodiment of the present invention.

The direct type backlight unit according to the first embodiment of the present invention includes a plurality of light emitting diodes 200; A light transmitting plate (100) in which the plurality of light emitting diodes (200) are arranged and in which a plurality of openings (110) are formed; A reflector 300 is disposed below the light transmissive plate 100 and positioned below the light transmissive plate 100.

In the direct type backlight unit according to the first embodiment, the light emitted from the plurality of light emitting diodes 200 is reflected by the reflector 300 and is emitted upward through the light transmissive plate 100.

In this case, since the openings 110 are formed in the region of the light transmissive plate 100 between the plurality of light emitting diodes 200, the light emitted from the plurality of light emitting diodes 200 is reflected by the reflector 300. ) And the openings 110 are emitted to the upper portion of the light transmissive plate 100 through the untransformed region of the light transmissive plate 100 and the openings 110.

Here, of the light a1 and a2 emitted from the plurality of light emitting diodes 200 and reflected by the reflector 300, an area of the light transmissive plate 100 that is close to each of the plurality of light emitting diodes 200. The light a1 emitted from the light a1 has a large light intensity, and the light a2 emitted to a region of the light transmissive plate 100 far from each of the plurality of light emitting diodes 200 has a light intensity that is relatively higher than that of the a1 light. Small as

Therefore, in the direct type backlight unit according to the first embodiment of the present invention, light a1 having a high light intensity is emitted through an area of the light transmissive plate 100 adjacent to each of the plurality of light emitting diodes 200. Light a2 having a relatively small light intensity is emitted through the openings 110, thereby eliminating a hot spot and improving the uniformity of the emitted light.

Meanwhile, optical sheets 500 for a backlight unit including a diffusion plate are positioned on the light transmissive plate 100, and a liquid crystal display panel is positioned on the optical sheets 500.

The distance between the light transmissive plate 100 and the reflector 300 may be 3 mm to 10 mm.

That is, when the distance between the light transmissive plate 100 and the reflector 300 is less than 3 mm, the light transmissive plate 100 and the reflector 300 are in close proximity to the light transmissive plate 100. Since the light emitted from the mounted light emitting diodes 200 is not reflected by the reflector 300 several times, the light does not spread, thereby decreasing the uniformity of the light emitted from the light transmissive plate 100.

In addition, when the distance between the light transmissive plate 100 and the reflector 300 is greater than 10 mm, it is difficult to thin the direct type backlight unit.

Referring to FIG. 1, the plurality of light emitting diodes 200 is arranged on a bottom surface of the light transmissive plate 100, and the plurality of light emitting diodes 200 is opposite to the reflector 300.

Therefore, the light emitted from the plurality of light emitting diodes 200 is reflected by the reflector 300 to be emitted to the upper portion of the light transmissive plate 100 through the light transmissive plate 100 and the openings 110. It can be.

In addition, in the direct type backlight unit of the present invention, the plurality of light emitting diodes 200 may be disposed in parallel on the bottom surface of the bottom chassis.

2A and 2B are schematic diagrams for describing a direct backlight unit according to a first embodiment of the present invention and a direct backlight unit of a comparative example.

In the direct backlight unit of the general comparative example, as shown in FIG. 2A, the light emitting diode 20 is mounted on the substrate 10, and the diffusion plate 30 is positioned above the light emitting diode 20. The distance L1 at which the light emitted from the light emitting diode 20 reaches the diffuser plate 30 depends on the distance from the light emitting diode 20 to the diffuser plate 30.

On the other hand, in the direct type backlight unit according to the first exemplary embodiment of the present invention, as shown in FIG. 2B, the light emitted from the light emitting diode 200 mounted under the light transmissive plate 100 is reflected by the reflector 300 and thus the By reaching the diffuser plate 30 through the region of the transparent plate 100 or through the opening 110 of the transparent plate 100, the light emitted from the light emitting diode 200 reaches the diffuser plate 30. The distance becomes a distance L2 from the light emitting diodes 200 to the reflector 300 and a distance L3 from the reflector 300 to the diffusion plate 30.

Therefore, the direct type backlight unit according to the first embodiment of the present invention has an advantage that the path of light reaching the optical sheets such as the diffusion plate is longer than that of the direct type backlight unit of the comparative example so that the light can be uniformly emitted.

Therefore, the direct type backlight unit of the present invention reflects the light emitted from the light emitting diode to the reflector and transmits the light transmissive plate, so that the path of the light can be extended to uniformly emit the light.

Here, the diffusion plate 30 in the substrate D of the direct backlight unit of the comparative example and the distance (D) from the reflector 300 to the diffuser plate 30 of the direct backlight unit according to the first embodiment of the present invention The interval D until is the same.

3 is a schematic diagram of a direct backlight unit according to a second embodiment of the present invention.

In the direct type backlight unit according to the second exemplary embodiment of the present invention, the reflective coating film 150 is formed on the lower surface of the light transmissive plate 100 on which the light emitting diode 200 is mounted, and a plurality of openings are formed in the reflective coating film 150. Fields 161 and 162 are formed.

That is, the direct type backlight unit according to the second embodiment includes a plurality of light emitting diodes 200; A light transmissive plate (100) in which the plurality of light emitting diodes (200) are arranged; A reflective coating film 150 formed on a surface of the light transmissive plate 100 in which the plurality of light emitting diodes 200 are present and having a plurality of openings 161 and 162 formed therein; A reflector 300 is disposed below the light transmissive plate 100 and positioned below the light transmissive plate 100.

According to the second embodiment, the light b1 and b2 emitted from the light emitting diode 200 have a path reflected by the reflector 300 and emitted through the '161' opening, or the reflector 300 and the Reflected by the reflective coating film 150 has a path that is emitted through the '162' opening.

Therefore, the light emitted from the light emitting diodes 200 is continuously reflected between the reflector 300 and the reflective coating film 150 to pass through the openings 161 and 162 through the openings 161 and 162. By being emitted to the top, there is an advantage that can emit light uniformly.

The reflective coating layer 150 may be configured as a specular reflector that directly reflects incident light or a diffuse reflector that scatters and reflects the incident light.

4 is a schematic configuration diagram illustrating an example of a light transmissive plate of a direct backlight unit according to a second embodiment of the present invention, and FIG. 5 is a light diagram of the direct backlight unit according to the first embodiment of the present invention. It is a schematic block diagram for demonstrating another example of a permeable plate.

The light transmissive plate 100 applied to the direct type backlight unit according to the second embodiment may be formed of a diffusion plate or a transparent resin plate.

The transparent resin plate may be formed of polycarbonate (PC) or poly (methyl methacrylate) (PMMA).

When the light transmissive plate 100 is a diffusion plate, as shown in FIG. 4, the light passing through the opening 161 is diffused and emitted to the light transmissive plate 100.

In addition, when the light transmissive plate 100 is a transparent resin plate, as shown in FIG. 5, light passing through the opening 161 is emitted through the light transmissive plate 100.

FIG. 6 is a schematic diagram for explaining a pattern shape of an example of openings applied to an embodiment of the present invention, and FIG. 7 is a schematic diagram for explaining a pattern shape of another example of the openings applied to an embodiment of the present invention. 8 is a view showing a part of the region of the light transmissive plate having an opening applied to the present invention.

A plurality of openings 170 penetrating the light transmissive plate are formed between the light emitting diodes 200 mounted on the light transmissive plate of the direct backlight unit of the first and second embodiments.

The plurality of openings 170 may be arranged in a matrix form as shown in FIG. 6.

The diameters of the plurality of openings 170 may be smaller as they approach the light emitting diodes 200.

For example, as shown in FIG. 7, the diameter of the opening '171' closest to the light emitting diode 200 is smaller than the diameter of the opening '172' closest to the second light emitting diode 200, and the light emitting diode 200 The diameter of the opening '172', which is the second proximate from), is designed to be smaller than the diameter of the opening '173', which is the third proximate from the light-emitting diode 200.

Here, the distance (l1) between the light emitting diode 200 and the opening '171', the distance l2 between the light emitting diode 200 and the opening '171' and the distance (l) between the light emitting diode 200 and the opening '171' ( The relationship between L3) is L3> L2> L1.

As such, the diameters of the plurality of openings 170 are designed to be smaller as they are closer to the light emitting diodes 200, so that light may be uniformly emitted through the light transmissive plate.

That is, since the light intensity incident to the light transmissive plate region is greater as the LED 200 approaches, the light amount of the smallest light passes through the opening '171' closest to the light emitting diode 200. The second amount of light passes through the second opening 172 that is closest to the light emitting diode 200, and the most amount of light passes through the second opening 172 that is closest to the third light emitting diode 200. Light may be evenly emitted through the light transmissive plate.

For reference, although the opening size of FIG. 7 is similar, the above-described principle, that is, the diameter of the plurality of openings 170 is designed to be smaller as it approaches the light emitting diode 200.

8 is a view showing a part of the region of the light transmissive plate having an opening applied to the present invention.

As shown in FIG. 8, openings 160 are formed in a region of the light transmissive plate 150 around the light emitting diode 200.

The diameter of the openings 170 is preferably 1㎛ ~ 10mm.

That is, when the diameters of the plurality of openings 170 are smaller than 1 μm, the amount of light emitted through the plurality of openings 170 is extremely small, and the diameter of the plurality of openings 170 is reduced. If it is larger than 10 mm, it is difficult to exist between the light emitting diodes 200.

In addition, the uniformity of light emitted from the light transmissive plate may be optimized by changing the size of the openings 170, the spacing and the density of the openings 170.

9A to 9C are simulation result graphs in the direct type backlight unit according to the comparative example of the present invention, and FIGS. 10A to 10C are simulation result graphs in the direct type backlight unit according to the embodiment of the present invention.

9A to 9C and 10A to 10C are modeled using 'Lighttools', an optical design tool, and then simulated.

First, in the direct type backlight unit according to the comparative example as illustrated in FIG. 2A, a hot spot is generated when referring to FIG. 9A, and an optical peak is generated in a region where the hot spot is generated when referring to FIG. 9B, which is a light intensity graph in the Y-axis direction. In FIG. 9C, which is a light intensity graph in the X-axis direction, a light peak is generated in a region where hot spots are generated, and thus uniformity of light emitted is poor.

And, in the direct type backlight unit according to the embodiment of the present invention, as shown in Figure 10a, by using the light-transmitting plate provided with the opening pattern, it can be seen that the uniformity of the light emitted by the hot spot is removed.

Also, referring to FIG. 10B, which is a light intensity graph in the Y-axis direction, and FIG. 10C, which is a light intensity graph in the X-axis direction, it can be seen that the hot spot is removed and the light is uniform.

And, as shown in Table 1 below, the light uniformity of the comparative example is 5%, whereas the light uniformity of the embodiment of the present invention is 74%, the direct type backlight unit according to the embodiment of the present invention shows that the light uniformity is significantly improved. Able to know.

Light uniformity Comparative example 5% Example 74%

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1 is a schematic configuration diagram of a direct type backlight unit according to a first embodiment of the present invention;

2A and 2B are schematic configuration diagrams for describing a direct backlight unit according to a first embodiment of the present invention and a direct backlight unit of a comparative example;

3 is a schematic configuration diagram of a direct type backlight unit according to a second embodiment of the present invention;

4 is a schematic configuration diagram illustrating an example of a light transmissive plate of a direct type backlight unit according to a second embodiment of the present invention;

FIG. 5 is a schematic diagram illustrating another example of a light transmissive plate of a direct type backlight unit according to a first embodiment of the present invention; FIG.

6 is a schematic diagram for explaining a pattern shape of an example of openings applied to an embodiment of the present invention.

7 is a schematic diagram for explaining a pattern shape of another example of the openings applied in the embodiment of the present invention.

8 is a view showing a part of the region of the light transmissive plate having an opening applied to the present invention;

9A to 9C are schematic diagrams of a direct type backlight unit according to a first embodiment of the present invention.

10A to 10C are schematic configuration diagrams of a direct type backlight unit according to a first embodiment of the present invention.

Claims (9)

A plurality of light emitting diodes; A light transmissive plate with the plurality of light emitting diodes arranged on a lower surface thereof and having a plurality of openings formed therein; And a reflector positioned below the light transmissive plate and spaced apart from the light transmissive plate. The method according to claim 1, The light transmissive plate, Direct type backlight unit composed of diffuser plate or transparent resin plate. The method according to claim 2, The material of the transparent resin plate, Direct backlight unit which is PC (polycarbonate) or PMMA (Poly (methyl methacrylate)). The method according to claim 1, And a distance between the light transmissive plate and the reflector is 3 mm to 10 mm. The method according to claim 1, The diameter of the openings 1㎛ 10mm direct backlight unit. The method according to claim 1, And a diameter of the plurality of openings decreases closer to the light emitting diode. The method according to claim 1, The light emitted from the plurality of light emitting diodes is reflected by the reflector to reflect the light emitted through the light transmissive plate and the openings so that the path of the light emitted from the plurality of light emitting diodes is long to uniformly emit the light. Direct type backlight unit with a path. A plurality of light emitting diodes; A light transmitting plate on which the plurality of light emitting diodes are arranged; A reflection coating film formed on a surface of the light transmissive plate in which the plurality of light emitting diodes are present and having a plurality of openings; And a reflector positioned below the light transmissive plate and spaced apart from the light transmissive plate. The method according to claim 8, The reflective coating film, A direct type backlight unit, which is a specular reflector that directly reflects incident light or a diffuse reflector that scatters and reflects incident light.

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