KR20210124590A - Direct backlight unit having local dimming function - Google Patents

Abstract

The present invention relates to a direct backlight device with an enhanced local dimming function. A direct type backlight device of the present embodiment includes: a substrate; a plurality of LED devices mounted on the substrate while forming a predetermined interval; a reflective member which forms a light source hole at a position corresponding to the LED element, and is coupled to an upper surface of the substrate while exposing the LED element through the light source hole; and a light blocking dam formed along the upper surface of the reflective member while forming a block in units of a predetermined area including one or more of the LED elements; and a sealing layer for sealing the LED element. Local dimming is implemented by driving the LED element in unit blocks formed by the light blocking dam. Therefore, diffusion or progress of light between neighboring unit blocks is blocked by the light blocking dam made of white material formed in units of predetermined blocks, thereby exhibiting excellent contrast ratio.

Description

Direct backlight unit having local dimming function

The present invention relates to a direct backlight device with enhanced local dimming function.

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

Unlike other display devices, the LCD does not emit light by itself, and thus requires a separate external light source to realize high-quality images. Therefore, the LCD further includes a backlight device of a surface light source in addition to the liquid crystal panel, and the backlight device uniformly supplies a high-brightness light source to the liquid crystal panel, thereby realizing a high-quality image. As described above, the backlight device refers to a surface lighting device for realizing an image of a non-emission type display device such as LCD, and may be classified as a direct lighting type or edge lighting type backlight device depending on the location of the light source. are separated A light emitting diode (hereinafter referred to as 'LED') having advantages such as small size, low power consumption, and high reliability is mainly used as a light source of the backlight device.

The direct backlight device is advantageous for realizing a large screen backlight device in a way that a plurality of LED light sources are disposed on a flat substrate to provide direct light, and the side-type backlight device has an LED light source disposed on the side of the light guide plate and passes through the light guide plate. It is advantageous for implementing a slim-type backlight device by providing light.

Recently, display devices have been applied and used in various types of display devices in addition to TVs and smart phones, and demands for image or luminance control in a specific area such as local dimming or scanning are also increasing depending on the types of display devices. At this time, in the case of LCD, image or luminance control for a specific area is generally possible with local dimming through the liquid crystal cell arrangement of the liquid crystal panel, but local dimming through the liquid crystal cell arrangement has a limitation in contrast ratio. Accordingly, in recent years, local dimming of the backlight device for a corresponding area is performed using a liquid crystal cell arrangement for local dimming, that is, individual on/off control of an LED light source.

However, in the direct backlight device according to the related art, the light of the LED light source that is individually driven in units of a predetermined area is diffused to neighboring areas while passing through the light mixing space or the diffusion plate, thereby limiting the implementation of precise local dimming. Accordingly, there is an increasing need to implement local dimming capable of exhibiting a better contrast ratio in response to an image of a display device that has recently become high-quality.

The present invention has been proposed to solve the above problems, and an object of the present invention is to provide a direct type backlight device capable of exhibiting a better contrast ratio by strengthening a local dimming function.

In the direct backlight device of this embodiment for solving the above problems, a substrate, a plurality of LED elements mounted on the substrate at a predetermined interval, a light source hole is formed at a position corresponding to the LED element, and the A reflective member coupled to the upper surface of the substrate while exposing the LED element through a light source hole, a light blocking dam formed along the upper surface of the reflective member while forming a block in units of a predetermined area including one or more of the LED elements, and, A sealing layer for sealing the LED element is included, and local dimming is implemented by driving the LED element in unit blocks formed by the light blocking dam.

In the backlight device of the present embodiment, the reflective member includes a first reflective surface formed on a side surface of the light source hole and a second reflective surface formed on an upper surface of the reflective member while connecting the first reflective surface of the neighboring light source hole may include.

In addition, in the backlight device of the present embodiment, the light blocking dam may include a third reflective surface formed on a side surface.

Also, in the backlight device of the present embodiment, the light blocking dam may have a polygonal planar shape.

In addition, in the backlight device of this embodiment, the light-shielding dam is TiO2, CaCO3, ZnS, Si, Ag, Al, SiO2, BaSO4, Al2O3 any one or more of the light reflective material may be composed of a mixed white resin.

According to the present invention having the above configuration, diffusion or propagation of light between neighboring unit blocks is blocked by a light blocking dam made of white material formed in units of predetermined blocks, thereby exhibiting an excellent contrast ratio, and the local dimming function is further strengthened. It works.

1 is a plan view showing a direct type backlight device according to the present embodiment;
2 is a longitudinal cross-sectional view showing a direct 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 in relation to one embodiment, and the location of individual components within each disclosed embodiment. Or 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, etc., may be exaggerated for convenience.

FIG. 1 is a plan view illustrating a direct type backlight device according to the present embodiment, and FIG. 2 is a vertical cross-sectional view illustrating the direct type backlight device according to the present embodiment, showing a cross-section in the direction A-A of FIG. 1 .

As shown in these figures, the backlight device of the present embodiment includes a substrate 100, a plurality of LED elements 200 mounted on the substrate while forming a predetermined interval, and a light source hole 300 through which the LED elements 200 are exposed. ') while forming a reflective member 300 coupled to the upper surface of the substrate 100, and a light blocking dam 400 protruding from the upper surface of the reflective member 300 while forming a predetermined region including one or more LED elements 200 and a sealing layer 500 filled on the reflective member 300 including the light source hole 300 ′ while sealing the LED device 200 , and a diffusion plate 610 on the sealing layer 500 upper surface. ) and the optical sheet 510 including the prism sheet 620 is coupled.

Specifically, the substrate 100 is configured to apply power and control signals to the LED device 200 by mounting the LED device 200, and is composed of a printed circuit board (PCB) or a flexible printed circuit board (FPCB). can be

The LED device 200 is a light source of the backlight device, and may be configured as a micro LED (mini LED), and is mounted on the substrate 100 by die bonding and wire bonding and electrically connected thereto. A plurality of LED elements 200 are mounted horizontally, vertically or in any direction while forming a predetermined interval. In addition, the LED device 200 may be configured as a top view type device emitting light upward or a multi-faceted light emitting device including an upper light emitting surface. In addition, the LED device 200 may be a blue light-emitting device or a white light-emitting device.

The reflective member 300 exposes the LED device 200 and is coupled to the upper surface of the substrate 100 , and diffuses and reflects the light emitted from the LED device 200 . The reflective member 300 for this purpose is composed of a sheet or plate having a high reflectance, and a plurality of light source holes 300 ′ are formed at positions corresponding to the respective LED elements 200 . Here, the high reflectance generally refers to a degree of having an excellent reflectance that can be used as a reflective material in a surface light source device. The light source hole 300 ′ may have a circular, rectangular, or polygonal planar shape.

The reflective member 300 may include a first reflective surface 310 formed in the light source hole 300 ′ and a second reflective surface 320 formed on an upper surface.

The first reflective surface 310 may form a vertical surface as a side surface of the light source hole 300 ′, but may also form an inclined surface or a concave or convex curved surface. That is, the diameter of the lower end of the light source hole 300 ′ may be relatively narrow with respect to the thickness direction of the reflective member 300 , and the diameter may increase toward the upper side. In addition, the first reflective surface 310 diffuses the light emitted from the LED device 200 to the upper portion of the second reflective surface 320 . That is, the first reflective surface 310 disperses light that can be focused on the upper portion of the LED device 200 to the upper portion of the second reflective surface 320 to improve light uniformity.

The second reflective surface 320 is formed on the upper surface of the reflective member 300 to reflect light distributed between the LED element 200 and the diffusion plate 610 upward to improve the brightness of the backlight device. The second reflective surface 320 extends from the first reflective surface 310 and connects adjacent light source holes 300 ′. In addition, the second reflective surface 320 diffuses the light distributed between the LED element 200 and the diffusion plate 610 . For this purpose, various shapes of patterns for light diffusion may be formed on the second reflective surface 320 .

The light blocking dam 400 protrudes above the second reflective surface 320 of the reflective member 300 while forming a block in units of a predetermined area. The light blocking dam 400 may form a unit block having a triangular shape, a square shape, a rhombus shape, or a polygonal shape in a plane shape, and may be divided into various shapes of symmetrical or asymmetrical shapes as necessary. In addition, the light blocking dam 400 includes at least one light source hole 300 ′ in the unit block, and prevents light in the unit block from diffusing or propagating to neighboring blocks.

The light blocking dam 400 may be made of white resin in which a light reflective material is mixed with a transparent resin. The transparent resin may include any one or more of PS, PC, PMMA, PE, PET, PP, MMA-styrene, and silicone, and the light reflective material is TiO2, CaCO3, ZnS, Si, Ag, Al, SiO2, BaSO4, It may include any one or more of Al2O3. The light blocking dam 400 using a transparent resin can be formed by curing after being formed on the upper surface of the reflective member 300 through a dispensing process, so it has an advantage that it can be formed by a simple process.

In addition, the light blocking dam 400 may have a rib shape, and a third reflective surface 410 may be formed on the side surface. The third reflective surface 410 reflects light that travels or diffuses laterally inside the light blocking dam 400 , and blocks the progress of the neighboring unit block. The third reflective surface 410 may have a vertical surface, an inclined surface, or a curved surface shape.

The sealing layer 500 is molded on the upper surface of the reflective member 300 including the light source hole 300 ′ to protect the LED device 200 and to diffuse the light emitted from the LED device 200 . For this purpose, the sealing layer 500 may be made of a resin material having high transparency, for example, a transparent material including any one or more of PS, PC, PMMA, PE, PET, PP, MMA-styrene, and silicone. It can be configured, and if it is a material having high transparency, it is not limited to the type.

The sealing layer 500 may be formed to a height forming a predetermined distance from the second reflective surface 320 including the inside of the light source hole 300 ′. Accordingly, light emitted from the LED device 200 is sufficiently diffused in the sealing layer 500 region to improve light uniformity.

The sealing layer 500 may be formed by curing a transparent gel-like resin after molding by a process such as dispensing molding. A light diffusing agent may be dispersed in the sealing layer 500 for light diffusion, and the light diffusing agent may include any one or more of TiO2, CaCO3, ZnS, Si, Ag, Al, SiO2, BaSO4, and Al2O3 dispersed therein. can be In addition, a phosphor for converting a wavelength of light emitted from the LED device 200 according to the type of the LED device 200 may be further dispersed in the sealing layer 500 .

The optical sheet 600 is a light control member for diffusing and condensing light emitted through the sealing layer 500 , and may include a diffusion plate 610 and an upper and lower prism sheet 620 . The diffusion plate 610 is seated on the upper end of the light blocking dam 400 on the sealing layer 500 , and in this case, the light blocking dam 400 may function as a support rib at which the upper end supports the diffusion plate 610 . A pair of upper and lower prism sheets 620 may be stacked on the diffusion plate 610 in a direction in which the arrangement of prisms is orthogonal to each other.

In the direct backlight device having the above configuration, the LED element 200 is driven in units of blocks formed by the light blocking dam 400 to implement local dimming. In this case, since the light blocking dam 400 blocks the diffusion and movement of light between neighboring unit blocks, the contrast ratio of the local driving can be greatly improved.

In addition, in the backlight device, a liquid crystal panel is laminated on an optical sheet to constitute a display device, and the liquid crystal panel implements a high-quality image with a surface light source provided by the backlight device.

Although exemplary embodiments of the present invention have been illustrated and described as described above, 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: substrate
200: LED element
300: reflective member 300': light source hole
400: shading dam
500: sealing layer
600: optical sheet

Claims (5)

Board;
a plurality of LED devices mounted on the substrate while forming a predetermined interval;
a reflective member that forms a light source hole at a position corresponding to the LED element and is coupled to the upper surface of the substrate while exposing the LED element through the light source hole;
a light blocking dam formed along an upper surface of the reflective member while forming a block in units of a predetermined area including at least one of the LED elements; and,
A sealing layer for sealing the LED element;
A direct type backlight device for realizing local dimming by driving the LED element in unit blocks formed by the light blocking dam. According to claim 1, wherein the reflective member,
and a first reflective surface formed on a side surface of the light source hole and a second reflective surface formed on an upper surface of the reflective member while connecting the first reflective surface of the neighboring light source hole. According to claim 2, wherein the light blocking dam,
A direct backlight device comprising a third reflective surface formed on a side surface. The method of claim 3, wherein the light blocking dam,
A direct-type backlight device in which a planar shape forms a polygonal shape. According to claim 1, wherein the light blocking dam,
Any one or more of TiO2, CaCO3, ZnS, Si, Ag, Al, SiO2, BaSO4, Al2O3 light-reflecting material is inside the transparent resin of any one or more of PS, PC, PMMA, PE, PET, PP, MMA-styrene, and silicone. A direct-type backlight device composed of mixed white resin.

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