KR20220030352A - Edge type backlight unit mini LED - Google Patents

Abstract

Disclosed is an edge type backlight device using a mini-LED as a light source. According to an embodiment of the present invention, the backlight device comprises: a cover bottom having a bottom unit and a vertical fastening unit having an edge of the bottom unit extending to a front surface, and having an accommodation space therein; a light guide plate disposed in the accommodation space; a light source module including a substrate, a plurality of mini-LEDs mounted on a front surface of the substrate at a predetermined interval in a longitudinal direction of the substrate, a reflective member formed on the front surface of the substrate along the periphery of the mini-LEDs and a resin layer for sealing the mini-LEDs while filling a light source space of the reflective member, and disposed at one side of the light guide plate to provide light of the mini-LEDs into the light guide plate; and an optical sheet disposed on an upper part of the light guide plate. Therefore, the luminance characteristics and color uniformity of a liquid crystal display can be improved or easily adjusted.

Description

Edge type backlight unit mini LED using a mini LED as a light source

The present invention discloses an edge type backlight device using a mini LED as a light source.

In general, a display device is a device that receives and displays an image signal, and includes a TV or a monitor. As a means for displaying an image, a liquid crystal display device (LCD: Liquid Crystal Display Device), an organic light emitting device (OLED: Organic Light) Various devices such as emitting display) and plasma display panel (PDP) are being used.

A liquid crystal display device is a display device in which a desired image can be displayed by individually supplying data signals according to image information to pixels arranged in a matrix form, and adjusting the light transmittance of the pixels. Since the liquid crystal display does not emit light by itself and is a light-receiving element that displays an image by controlling the transmittance of light coming from the outside, a separate device for irradiating light to the liquid crystal panel, that is, a backlight unit is required.

The backlight device is divided into an edge type and a direct type according to the arrangement structure of the LED light source. The edge type has a structure in which the light source is disposed on the side of the light guide plate, and the direct type has a structure in which a plurality of light sources are optical It has a structure disposed under the seat. The edge type is advantageous in realizing a slim type display device due to a structure in which the light source is disposed on the side of the light guide plate, and the surface light source is converted and emitted through the light guide plate, so that the light uniformity is excellent.

As a light source of a backlight device, an LED having advantages such as miniaturization, weight reduction, and low power consumption is mainly used. Recently, the chip size of the LED light source has also been gradually reduced, which helps to reduce the power consumption of the liquid crystal display and to improve the light uniformity.

On the other hand, the backlight device may exhibit various effects when the light emission angle is efficiently controlled by using a mini LED or a micro LED as a light source. In particular, in an edge-type backlight device, when a mini LED or micro LED is used as a light source, the bezel width of the light source area can be reduced according to the directional angle of the light emitted from the light source module, and the number of LEDs constituting the light source module can be reduced to a minimum. This may reduce the manufacturing cost.

Nevertheless, in the current edge-type backlight device using a mini LED or a micro LED as a light source, there is a problem in that the beam angle of the light source cannot be efficiently controlled.

The present invention has been proposed to solve the above problems, and in an edge-type backlight device using a mini LED as a light source, the bezel width of the light source region can be reduced by efficiently controlling the beam angle of the light source, and the number of LEDs can be reduced. An object of the present invention is to provide a backlight device capable of reducing manufacturing cost by minimizing it.

The backlight device of this embodiment for solving the above problems includes a cover bottom having a bottom portion and a vertical fastening portion extending to the front of the edge of the bottom portion and forming an accommodation space therein, a light guide plate disposed in the accommodation space, A plurality of mini LEDs mounted on the front surface of the substrate while forming a predetermined interval in the longitudinal direction of the substrate and the reflective member formed on the front surface of the substrate along the periphery of the LED and the light source space of the reflective member A light source module including a resin layer sealing the LED, disposed on one side of the light guide plate to provide the light of the plurality of mini LEDs to the inside of the light guide plate, and an optical sheet disposed on the light guide plate.

In this embodiment, the mini LED may be composed of an LED chip having a diameter of 500 μm or less.

In addition, in the present embodiment, the mini LED is composed of a blue chip emitting light in a wavelength range of 450 nm±10 nm, and a fluorescent layer may be further provided on the light incident surface or the light output surface side of the light guide plate.

In addition, in the present embodiment, the reflective member may have a higher thickness than the LED, and the directional angle of the light emitted from the light source module may be controlled according to the thickness of the reflective member.

In addition, in this embodiment, the resin layer may be composed of a methyl-based silicone resin or a phenyl-based silicone resin.

In the backlight device of the present invention, since the number of light sources can be easily adjusted by employing a mini LED as a light source, the luminance characteristics and color uniformity of the liquid crystal display can be improved or easily adjusted. ,

In addition, in the backlight device of the present invention, the beam angle can be easily controlled by a combination of a mini-LED, which is a light source, and a reflective sheet formed around the LED, thereby improving a hot spot and easily reducing a bezel width.

In addition, since the backlight device of the present invention uses a mini-LED as a light source, a light source module having a multi-layer structure can be configured, and the light guide plate can be arranged in a multi-layer structure corresponding to this, so there is an advantageous effect for luminance control and local dimming. .

1 is a cross-sectional view showing an edge type backlight device according to the present embodiment;
2 is a front view and a side view showing a light source module, which is a main part of FIG. 1;
3 is a graph showing the orientation angle of the light source module according to the present embodiment;
4 is a conceptual diagram showing the light output characteristics of the light source module according to the present embodiment;
5 is a cross-sectional view illustrating another example of an edge-type backlight device according to the present embodiment.

The present invention and the technical problems achieved by the practice of the present invention will be made clear by the preferred embodiments described below. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

It should be understood that the differences between the embodiments described below are not mutually exclusive. That is, without departing from the spirit and scope of the present invention, the specific shapes, structures and characteristics described may be implemented in other embodiments with respect to one embodiment, and the location of individual components within each disclosed embodiment Alternatively, it should be understood that the arrangement may be changed, and similar reference numerals in the drawings refer to the same or similar functions over several aspects, and the length, area, thickness, and the like may be exaggerated for convenience. In the description of this embodiment, top, bottom. Expressions such as left, right, first, second, etc. indicate relative positions, directions, and sequences, and their technical meanings are not limited by dictionary meanings.

1 is a cross-sectional view showing an edge-type backlight device according to the present embodiment, FIG. 2 is a front view and a side view showing a light source module which is a main part of FIG. 1, and FIG. 3 is a graph showing the orientation angle of the light source module according to this embodiment and FIG. 4 is a conceptual diagram illustrating the light output characteristics of the light source module according to the present embodiment.

First, referring to FIGS. 1 and 2, the backlight device of this embodiment includes a cover bottom 100, a first reflective sheet 200 seated on the inner surface of the cover bottom, a light guide plate 300 disposed in the inner space of the cover bottom, It includes a light source module 400 disposed on one side of the light guide plate and an optical sheet 500 stacked on the light guide plate.

Specifically, the cover bottom 100 accommodates the optical member and the light source therein, and constitutes a rear cover of the backlight unit that protects the respective components.

The cover bottom 100 is a hexahedral housing with an open upper side, and a vertical fastening part 120 bent upward along the edge of the bottom part 110 on a square plate is formed, and each part is accommodated therein. space is formed. The bottom part 110 may have a rectangular plate shape, and a back cover may be assembled on the rear surface or the bottom part 100 may replace the back cover. The vertical fastening part 120 may be provided with fastening means for fastening the guide panel (not shown). The cover bottom 100 is preferably made of a material exhibiting excellent rigidity and heat dissipation characteristics, and may be made of, for example, aluminum or an aluminum alloy material.

The first reflective sheet 200 is coupled to the inner surface of the cover bottom 100 to reflect light leaking downward from the light guide plate 300 upward, thereby blocking light leakage and improving the brightness of the backlight device. The first reflective sheet 200 may be formed of a sheet or film having excellent light reflectance, and may be formed by coating a light reflective material such as Ag on the inner surface of the cover bottom 100 .

The light guide plate 300 is a light conversion element that receives light from a plurality of point light sources from the light source module 400 and converts the light to a planar light source through total internal reflection and emits the light upward. For this purpose, the light guide plate 300 is made of a transparent acrylic resin having a predetermined refractive index, and for example, PMMA (Polymethylmethacrylate), PS (Poly styrene), MS (Meta styrene) or PC (Polycarbonate). can The light guide plate 300 is composed of a plate or sheet having a predetermined thickness, at least one side of which constitutes a light incident surface on which light is incident, a lower surface of which constitutes a reflective surface that reflects light, and an upper surface of which light is emitted. composes the exit surface.

In addition, a fluorescent layer 310 may be formed on the light incident surface of the light guide plate 300 . The fluorescent layer 310 converts the wavelength of the light emitted from the LED 420 to be emitted as white light. The fluorescent layer 310 may be formed by attaching a fluorescent film to the light-receiving surface or by coating a fluorescent material on the light-receiving surface. In addition, the fluorescent layer 310 may be formed by being coated on the light exit surface of the light guide plate 300 , or a fluorescent sheet may be laminated on the light guide plate 300 instead of the fluorescent layer.

The light source module 400 is configured to inject light from a plurality of point light sources into the light guide plate 300 , and is disposed on at least one side of the light guide plate 300 in the inner space of the cover bottom 100 . The light source module 400 may be adhered to the vertical fastening unit 120 through an adhesive member (not shown) such as a double-sided tape, and the LED 420 , which is a light emitting source, is disposed to face the light incident surface of the light guide plate 300 . .

In the light source module 400 , a plurality of LEDs 420 are mounted on a substrate 410 , and a second reflective sheet 430 is coupled along the periphery of the LED 420 on the upper surface of the substrate 410 , and the second reflection In the light source space inside the sheet 430 , the resin layer 440 is molded while sealing the LED 420 .

The substrate 410 is printed with a predetermined circuit for driving the LED 420 and may be formed of a band-shaped PCB or FPCB having a predetermined width and length. The substrate 410 is fixed by mounting the LED 420 on the front side and bonding to the vertical fastening part 120 of the cover bottom 100 via a double-sided tape on the back side.

A plurality of LEDs 420 are mounted on the substrate 410 at predetermined intervals in the longitudinal direction as light sources of the backlight device. The LED 420 is configured as a miniaturized mini LED. The light source module 400 is advantageous in achieving high brightness since a large number of light sources can be mounted on the substrate 410 of a limited area by configuring the light source as the mini LED 420 . In addition, since the light source module 400 using the mini LED 420 can easily adjust the number of LEDs, the luminance characteristics and color uniformity of the liquid crystal display can be improved.

The LED 420 may be classified into various types of LED light sources according to the size of the LED chip. The mini LED of this embodiment has a horizontal and vertical diameter of 500 μm or less, and a thickness of **** μm or less . Consists of LED chips. In addition, the LED 420 is composed of a chip emitting light in the blue region, preferably composed of a blue chip emitting light in a wavelength range of 450 nm±10 nm. The blue light emitted from the LED 420 is wavelength-converted in the fluorescent layer 310 to emit white light.

The second reflective sheet 430 is formed on the substrate 410 along the periphery of the LED 420 , and controls the beam angle of light traveling from the light source module 400 to the light guide plate 300 , and the light source module 400 . The light distributed between the light guide plate 300 and the light guide plate 300 is re-entered into the light guide plate 300 . For this purpose, the second reflective sheet 430 may be formed to have a predetermined thickness that is at least thicker than the LED 420 . The second reflective sheet 430 may be formed by attaching a sheet or film having excellent light reflectance to the substrate 410 , or may be formed by coating a surface of the substrate with a light reflective material such as Ag.

The resin layer 440 is filled in the light source space inside the second reflective sheet 430 to seal and protect the LED 420 , and at the same time improve light extraction efficiency, and first diffuse the light emitted from the LED 420 . It is a configuration that makes The resin layer 440 may be made of a silicone resin of a transparent material, and as long as it is a material capable of transmitting and diffusing light, it may be made of various materials. In addition, a light diffusing agent may be mixed with a silicone resin constituting the resin layer 440 .

The silicone resin should have a predetermined refractive index, and as the refractive index increases, light extraction efficiency may be improved. Methyl-based silicone having a refractive index of 1.41 may be applied to the silicone resin of this embodiment, and phenyl-based silicone having a high refractive index of 1.53 to 1.55 may be applied to further increase light extraction efficiency.

Referring to FIG. 3 , the light source module 400 configured as described above exhibits a wide beam angle with respect to the longitudinal direction (x-x' direction) and the width direction (y-y' direction) of the substrate 410 . That is, in the light source module 400 of this embodiment, 50% or more of the light is distributed with respect to the center in a wide range of about 140° with respect to the longitudinal direction (x-x') as shown in (a), and as shown in (b). It can be seen that 50% or more of the light is distributed from the center in a wide range of about 120° with respect to the width direction (y-y'). Therefore, the light source module 400 of this embodiment exhibits a wide beam angle by a combination of a plurality of mini LEDs 420 , the second reflective sheet 430 and the resin layer 440 , and improves the hot spot to improve the bezel width of the light source area. has the effect of reducing

In addition, referring to FIG. 4 , the light source module 400 of the present embodiment may control the orientation angle by adjusting the thickness t of the second reflective sheet 430 . Referring to the drawings, the light source module 400 emits light at an orientation angle of about 140° when the thickness t of the second reflective sheet 430 is 0.2 mm as shown in (a), and as shown in (b). When the thickness (t) of the second reflective sheet 430 is 0.5 mm, it has a directivity angle of about 120°. In this case, as the LED 420, an LED chip having a thickness of *** μm was used. By appropriately adjusting the thickness t of the second reflective sheet 430 as described above, the orientation angle can be easily controlled according to the purpose or function of the liquid crystal display to which the backlight device is applied.

The optical sheet 500 is disposed on the light guide plate 300 to condense and diffuse the light emitted from the light guide plate 300 so that it is emitted with a wide viewing angle and high luminance. The optical sheet 500 may include a diffusion sheet and a pair of prism sheets. The light emitted from the light guide plate 300 is condensed and diffused while passing through the diffusion sheet and the pair of prism sheets to have a predetermined luminance and a viewing angle.

5 is a cross-sectional view illustrating another example of an edge-type backlight device according to the present embodiment.

In the edge-type backlight device of this embodiment, the LEDs 420 of the light source module 400 are mounted in n columns in a plurality of longitudinal directions (x-x'). For example, the LEDs 420 form a structure in two upper and lower rows, and two light guide plates 300 arranged in two upper and lower rows corresponding thereto are stacked on the front surface of the LEDs 420 in each column. That is, the light guide plate 300 and the LED 420 disposed on the light incident surface of the light guide plate form a top and bottom two-layer structure.

In the backlight device having a two-layer structure as described above, the upper LED 420-1 or the lower LED 420-2 is dividedly driven to selectively generate a surface light source from the upper light guide plate 300-1 or the lower light guide plate 300-2. By allowing it to be emitted, it is advantageous for local dimming driving. To this end, light patterns for guiding light emission in different regions may be formed on the upper light guide plate 300-1 and the lower light guide plate 300-2.

In addition, the backlight device having the above configuration has an effect of selectively controlling the luminance by driving only the LEDs 420 of one layer or driving the LEDs 420 of all layers.

In the present embodiment, the LED 420 and the light guide plate 300 have a two-layer structure, but the present invention is not limited thereto, and a multi-layer structure more than that may be formed if necessary.

As described above, although exemplary embodiments of the present invention have been illustrated and described, various modifications and other embodiments may be made by those skilled in the art. All such modifications and other embodiments are intended to be contemplated and included in the appended claims without departing from the true spirit and scope of the present invention.

100: cover bottom
110: bottom part 120: vertical fastening part
200: first reflective sheet
300: light guide plate 310: fluorescent layer
400: light source module
410: substrate 420: LED
430: second reflective sheet 440: resin layer
500: optical sheet

Claims (5)

a cover bottom having a bottom part and a vertical fastening part having an edge of the bottom part extending to the front and forming an accommodating space therein;
a light guide plate disposed in the accommodation space;
A substrate; a light source module including a resin layer for sealing the LED while being filled, the light source module being disposed on one side of the light guide plate to provide the light of the plurality of mini LEDs to the inside of the light guide plate; and
and an optical sheet disposed on the light guide plate. The method of claim 1, wherein the mini LED is
A backlight device comprising an LED chip having a diameter of 500 μm or less. 3. The method of claim 2,
The mini LED is composed of a blue chip that emits light in a wavelength range of 450 nm±10 nm,
The backlight device, further comprising a fluorescent layer on the light-incident surface or the light-exit surface side of the light guide plate. The method of claim 1,
The reflective member has a thickness higher than that of the LED, and a beam angle of light emitted from the light source module is controlled according to the thickness of the reflective member. According to claim 1, wherein the resin layer,
A backlight device comprising a methyl-based silicone resin or a phenyl-based silicone resin.

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