KR102581721B1 - Liquid crystal display device - Google Patents

Abstract

The liquid crystal display device according to the present invention includes a backlight unit, a light source housing, and a light leak blocking pad. The backlight unit includes a light guide plate having a light incident surface and a light source that irradiates light to the light incident surface from a side of the light guide plate. The light source housing covers the light source and the upper part of the light receiving surface. The light leak blocking pad is interposed between the light source housing and the light guide plate and is attached to the lower part of the light source housing. At least one edge of the light source housing to which the light leak blocking pad is attached has a chamfered shape.

Description

Liquid crystal display device {LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to a backlight unit and a liquid crystal display device including the same.

Liquid crystal displays are used in portable computers such as laptop PCs, office automation equipment, audio/video equipment, and indoor and outdoor advertising display devices. The liquid crystal display device displays images by controlling the electric field applied to the liquid crystal layer of the liquid crystal panel 100 to modulate light incident from a back light unit (BLU).

Recently, in laptops and portable electronic devices, along with the miniaturization of equipment, there are increasing attempts to increase the proportion of the display area where the actual image is displayed in the display device. To this end, efforts are being made to minimize the size of the non-display area forming the border of the display device, that is, the bezel.

The purpose of the present invention is to provide a liquid crystal display device that can ensure uniformity of the amount of light provided from the light source at the light incident area.

The liquid crystal display device according to the present invention includes a backlight unit, a light source housing, and a light leak blocking pad. The backlight unit includes a light guide plate having a light incident surface and a light source that irradiates light to the light incident surface from a side of the light guide plate. The light source housing covers the light source and the upper part of the light receiving surface. The light leak blocking pad is interposed between the light source housing and the light guide plate and is attached to the lower part of the light source housing. At least one edge of the light source housing to which the light leak blocking pad is attached has a chamfered shape.

The light source housing may include a first side relatively adjacent to the light source and a second side relatively spaced apart from the light source. A chamfered shape may be formed at the edge of the second side.

The light source housing may have a first width at a central area and a second width at the edges. The first width may be wider than the second width.

The width of the light source housing may gradually decrease towards the edges, in areas having a chamfered shape.

The liquid crystal display device according to the present invention has a liquid crystal panel disposed on the top of the backlight unit, and a frame disposed between the liquid crystal panel and the backlight unit to support the lower part of the liquid crystal panel and have a frame shape with the center penetrating and a shape that is partially open at the light receiving portion. It may further include a guide panel having. Among the light sources, the light source disposed at one edge may be disposed at a certain distance inward from the boundary of the light output area defined by the combination structure of the guide panel and the light source housing.

The light source housing may include a white colored plastic material.

The light leak blocking member has a black color and may be made of single-sided tape or plastic material.

The liquid crystal display device according to the present invention may further include a cover bottom that accommodates the backlight unit inside. The cover bottom may include an upper support portion, a side support portion, and a lower support portion that are formed by double bending at the light incident portion. The light source housing is interposed between the upper support and the light source, and may be attached to the upper support with an adhesive member.

The light source may be accommodated in an internal space provided by a combination structure of an upper support part, a side support part, and a lower support part. The liquid crystal panel may be supported by an upper support portion at the light receiving portion.

By applying a new structure, the present invention can uniformly control the amount of light contributing to the light exiting the liquid crystal panel from all areas of the light incident area. Accordingly, it has the advantage of preventing display quality deterioration due to luminance deviation in the light incident area.

By applying a new structure, the present invention has the advantage of being able to sufficiently uniformly provide light to a light incident surface of a preset area even with a relatively small number of light sources.

1 is an exploded perspective view of a liquid crystal display device according to the present invention.
FIG. 2 is a cross-sectional view taken along the line I-I' of FIG. 1, schematically showing the light incident portion of the liquid crystal display device.
Figures 3 and 4 are diagrams to explain problems caused by luminance deviation in the light incident area.
Figure 5 is a diagram for explaining the shape of a light source housing in which light leak blocking pads are laminated according to a preferred embodiment of the present invention.
Figures 6 and 7 are diagrams for explaining the effects of the present invention.
Figure 8 is a diagram for explaining a preferred application example of a light source housing in which a light leak blocking pad is laminated.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. Like reference numerals refer to substantially the same elements throughout the specification. In the following description, if it is determined that a detailed description of a known technology or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In describing various embodiments, the same components may be representatively described at the beginning and omitted in other embodiments.

Terms containing ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

1 is an exploded perspective view of a liquid crystal display device according to the present invention. FIG. 2 is a cross-sectional view taken along the line I-I' of FIG. 1, schematically showing the light incident portion of the liquid crystal display device.

Referring to Figures 1 and 2, the liquid crystal display device of the present invention includes a liquid crystal panel 100 and a backlight unit disposed below the liquid crystal panel 100.

The liquid crystal panel 100 may include an upper substrate 110, a lower substrate 130, and a liquid crystal layer interposed between the upper substrate 110 and the lower substrate 130. The liquid crystal layer may be implemented in at least one mode among various liquid crystal modes. The mode may be a vertical electric field driving method such as TN (Twisted Nematic) mode and VA (Vertical Alignment) mode, or a horizontal electric field driving method such as IPS (In Plane Switching) mode and FFS (Fringe Field Switching) mode. .

The liquid crystal display device may further include a panel driver that transmits a signal to drive the liquid crystal panel 100. The panel driver may include at least one circuit film 140 bonded to the liquid crystal panel 100, and a printed circuit board 150 connected to the circuit film 140. The circuit film 140 may be implemented as a chip on film in which a driving integrated circuit (IC) is mounted on a flexible film, but is not limited thereto. One end of the circuit film 140 may be connected to the liquid crystal panel 100, and the other end may be connected to the printed circuit board 150.

The backlight unit is provided below the liquid crystal panel 100 and irradiates light to the back of the liquid crystal panel 100. The backlight unit includes a light source 211, a light guide plate 220, and an optical sheet 230. The light supplied from the light source 211 to the light incident surface of the light guide plate 220 is converted into a surface light source form and is emitted to the front of the light guide plate 220, while passing through the optical sheet 230 located on the light guide plate 220. It is uniformly irradiated to the back of the liquid crystal panel 100.

The light source 211 may be provided in the form of a light emitting diode (LED) or a package thereof, but is not limited thereto. The light source 211 irradiates light to the side of the light guide plate 220 while facing at least one side (or light receiving surface) of the light guide plate 220 .

The light source 211 turns on and off by receiving an electrical signal from the driver of the light source 211 through the light source printed circuit board 213. That is, the light source 211 may emit light in response to a light source 211 driving signal from the light source 211 driver. A circuit for electrically connecting the light source 211 and the driver of the light source 211 is formed on the light source printed circuit board 213.

The light guide plate 220 is a plate made of transparent plastic, for example, polymethly methacrylate (PMMA), and converts light in the form of a point light source 211 or a line light source 211 into light in the form of a surface light source. It plays a role.

The optical sheets 230 can diffuse the light incident from the light guide plate 220, control the path of the light at an angle substantially perpendicular to the light incident surface of the liquid crystal panel 100, and improve the luminance characteristics of the light. there is. The optical sheet 230 may be made of a stacked combination of two or more selected from a diffusion sheet, a prism sheet, a dual brightness enhancement film, and a lenticular sheet, but is not limited thereto.

Below the light guide plate 220, a reflective sheet 240 may be disposed to reflect light incident from the light guide plate 220 to increase the efficiency of light incident on the liquid crystal panel 100. The reflective sheet 240 may be adhered to the cover bottom 310. A side reflection sheet may be further disposed on at least one side of the light guide plate 220 to reflect light incident from the light guide plate 220 to increase the efficiency of light incident on the liquid crystal panel 100. The guide panel 320 and the cover bottom 310 may be fixed to each other through at least one fixing member.

The liquid crystal panel 100 and the backlight unit can be implemented as a liquid crystal module (LCM) by being assembled together by case members such as the guide panel 320, cover bottom 310, and light source housing 330.

The guide panel 320 is disposed below the liquid crystal panel 100. The guide panel 320 is provided between the liquid crystal panel 100 and the backlight unit and supports the edge of the liquid crystal panel 100 from the bottom. The guide panel 320 is provided between the liquid crystal panel 100 and the optical sheet 230 to maintain a constant distance between the liquid crystal panel 100 and the optical sheet 230. The guide panel 320 may have a rectangular frame shape with the center penetrating, but may have a shape that is partially open at the light receiving part. The guide panel 320 may be made of a plastic-based material that can be formed with a mold, such as polycarbonate.

The cover bottom 310 may be arranged to surround the side and back of the backlight unit. In the internal space provided by the cover bottom 310, a backlight unit including a light source 211, a light guide plate 220, and at least one optical sheet 230 is accommodated.

The cover bottom 310 may have a double-bent structure in a “ㄷ” shape at the light incident portion. That is, the cover bottom 310 may include an upper support part 311, a side support part 312, and a lower support part 313 that are formed by double bending at the light incident part. The upper support part 311 may support the edge of the liquid crystal panel 100 from the lower part. A first adhesive member 351 may be interposed between the upper support portion 311 and the liquid crystal panel 100, and the liquid crystal panel 100 may be fixed to the cover bottom 310 by the first adhesive member 351. there is.

The light source 211 may be accommodated in an internal space provided by a combination structure of the upper support part 311, the side support part 312, and the lower support part 313. The upper support portion 311 may cover at least a portion of the upper surface of the light source 211 and the upper surface of the light guide plate 220. The side support may cover the side of the light source 211. The lower support portion 313 may cover at least a portion of the lower surface of the light source 211 and the lower surface of the light guide plate 220. The cover bottom 310 may include a material having high thermal conductivity and high rigidity to smoothly dissipate heat from the driving circuit and the light source 211 to the outside. As an example, the cover bottom 310 is made of aluminum, aluminum nitride (AlN), electro-galvanized steel sheet (EGI), stainless steel (SUS), galvalume (SGLC), aluminum-plated steel sheet (aka ALCOSTA), and tin-plated steel sheet (SPTE). It can be manufactured from a metal plate such as the like. Additionally, these metal plates may be coated with a high conductivity material to promote heat transfer.

The light source housing 330 is disposed between the light source 211 and the upper support portion 311 of the cover bottom 310 at the light incident portion. The light source housing 330 may have a plate shape. A second adhesive member 353 may be interposed between the light source housing 330 and the upper support portion 311 of the cover bottom 310, and the light source housing 330 may be attached to the cover bottom ( 310). The light source housing 330 is disposed above the light input portion of the light source 211 and the light guide plate 220, and spreads or guides the light provided from the light source 211 toward the light guide plate 220, thereby preventing light loss and light leakage. can be performed. The light source housing 330 may be made of a white plastic material to reflect incident light, but is not limited thereto.

A light leak blocking pad 340 is disposed on the back of the light source housing 330. The light leak blocking pad 340 is interposed between the light source housing 330 and the light guide plate 220 at the light incident area. The light leak blocking pad 340 may be laminated to the back of the light source housing 330. As an example, the light leak blocking pad 340 may be made of a single-sided tape with adhesive on one side, and one side may be attached to the back of the light source housing 330. As another example, the light leak blocking pad 340 may be formed of a plastic material such as PET (polyethylene terephthalate), and may be attached to the back of the light source housing 330 through an adhesive member such as double-sided tape.

The light leak blocking pad 340 may have optical properties that block light. For example, the light leak blocking pad 340 may be implemented in black color. The present invention can block light directed in an unwanted direction by providing a light leak blocking pad 340. Accordingly, luminance loss can be prevented and display quality deterioration due to poor light leakage can be prevented.

Figures 3 and 4 are diagrams to explain problems caused by luminance deviation in the light incident area. Hereinafter, for convenience of explanation, other components will be omitted and only the configurations of the light source 211, the light guide plate 220, the light source housing 330, and the light leak blocking pad 340 will be described.

Referring to FIGS. 3 and 4 , the light sources 211 are disposed opposite to the light incident surface of the light guide plate 220 and are sequentially arranged along the first direction (eg, x-axis direction). The light sources 211 are arranged at predetermined intervals. The spacing between the light sources 211 may be set in consideration of the beam angles of the light sources 211. Light incident from the light source 211 through the light entrance surface of the light guide plate 220 proceeds through total reflection inside the light guide plate 220. Light traveling through total reflection is emitted toward the receiving light surface.

The arrow in the drawing schematically shows the direction of light travel, and shows only the light that is not lost by the light source housing 330 and the light leak blocking pad 340 in the light incident part and that contributes to the exiting light to the liquid crystal panel. .

As described above, since the light provided from the light sources 211 is provided within the range of a preset beam angle, the light provided from the neighboring light sources 211 overlaps in one area. Accordingly, the amount of light incident through the light sources 211 in the central area of the light incident portion is greater than the amount of light provided from one light source 211.

However, at the edge of the light incident portion, only light provided from one light source 211 is incident. Therefore, a difference occurs in the amount of light in the central area of the light incident area and the amount of light at the edges of the light incident area. In other words, a problem of luminance non-uniformity occurs due to variation in the amount of light depending on the location of the light incident area. Deviation in luminance at the light incident area is problematic because it may be perceived by the user as a poor display.

In order to prevent this, it is possible to consider a method of controlling the light absorption rate from the central area to the edge by adjusting the color of the light leak blocking pad 340, for example, by giving a gradient to the color of the light leak blocking pad 340. there is. However, in the case of the light leak blocking pad 340, since tape, etc. may be used, there are process difficulties in applying the gradient, making it difficult to actually apply it to the liquid crystal display device.

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

Figure 5 is a diagram for explaining the shape of a light source housing in which light leak blocking pads are laminated according to a preferred embodiment of the present invention. Figures 6 and 7 are diagrams for explaining the effects of the present invention.

Referring to FIG. 5 , the light source housing 330 to which the light leak blocking pad 340 is laminated has a shape 350 in which at least one edge (corner) is chamfered. The chamfered shape 350 may mean a shape in which at least one edge of the light source housing 330 is partially depressed inward. That is, at least one edge of the light source housing 330 to which the light leak blocking pad 340 is laminated is partially removed in the second direction (for example, the y-axis direction or the width direction). Accordingly, the light source housing 330 in which the light leak blocking pad 340 is laminated has a shape in which the first width W1 of the central area and the second width W2 of the edge are different. Here, the first width W1 is wider than the second width W2.

One side of the light source housing 330 that is chamfered refers to a side spaced apart from the light source 211. In other words, the light source housing 330 may have a plate shape when viewed on a plane, and may include a first surface (P1) and a second surface (P2) that face each other in the width direction. Here, the first surface (P1) is a surface adjacent to the light source 211, and the second surface (P2) is a surface relatively spaced apart from the light source 211 compared to the first surface (P1). The second surface (P2) may be parallel to the first surface (P1). The chamfered shape 350 may be a shape formed by partially removing the second surface P2 of the light source housing 330 inward.

Referring to FIG. 6, the light sources 211 are disposed to face the light incident surface of the light guide plate 220 and are sequentially arranged along one direction. The light sources 211 are arranged at predetermined intervals. The spacing between the light sources 211 may be set in consideration of the beam angles of the light sources 211. Light incident from the light source 211 through the light entrance surface of the light guide plate 220 proceeds through total reflection inside the light guide plate 220. Light traveling through total reflection is emitted toward the receiving light surface.

Since the light provided from the light sources 211 is provided within the range of a preset beam angle, the light provided from the neighboring light sources 211 overlaps in one area. Accordingly, the amount of light incident through the light sources 211 in the central area of the light incident portion is greater than the amount of light provided from one light source 211. In contrast, at the edge of the light incident portion, only light provided from one light source 211 is incident. Therefore, a difference occurs in the amount of light in the central area of the light incident area and the amount of light at the edges of the light incident area. That is, the amount of light provided from the light source 211 is different between the central area and the edge of the light incident area.

The arrow in the drawing schematically shows the direction of light travel, and shows only the light that is not lost by the light source housing 330 and the light leak blocking pad 340 in the light incident part and that contributes to the exiting light to the liquid crystal panel. .

In the present invention, the edges of the light source housing 330 and the light leak blocking pad 340 have a chamfered shape 350. In this case, at the edge of the light incident portion, the light provided to the chamfered portion among the light provided from the light source 211 disposed at the edge is not lost or reflected by the light source housing 330 and the light leak blocking pad 340, and the liquid crystal It can contribute to light output to the panel. That is, in a preferred embodiment of the present invention, compared to the structure shown in FIG. 3, the light provided to the chamfered portion at the edge of the light incident portion can contribute more to the light exiting the liquid crystal panel, so the insufficient amount of light at the edge of the light incident portion This can be compensated.

This is by applying a new shape to the light source housing 330 and the light leak blocking pad 340 without modifying the overall design of the backlight unit, such as the light source 211 and the light guide plate 220, so that the This means that the amount of light and the amount of light at the edges of the light incident area can be controlled uniformly. In the light source housing 330 in which the light leak blocking pad 340 is laminated, the chamfered area may be selected in consideration of the amount of light that needs to be compensated.

Figure 7 (a) is a comparative example and is a diagram schematically showing the positional relationship between the light exit area A/A and the light source 211. 7(b) and 7(c) are diagrams schematically showing the positional relationship between the light exit area A/A and the light sources 211 according to a preferred embodiment of the present invention. The light exit area (A/A) refers to an area where light actually exits the liquid crystal panel 100 without being shielded and lost by another case member. For example, the light exit area A/A may be defined as an area exposed by the combined structure of the guide panel 320 and the light source housing 330. Alternatively, the light exit area A/A may be defined as an active area from which actual light of the liquid crystal panel 100 is emitted.

Referring to FIG. 7, as described above, a preferred embodiment of the present invention applies a chamfer to the edge of the light source housing 330 on which the light leak blocking pad 340 is laminated, thereby contributing to the outgoing light from the light incident portion to the liquid crystal panel. The amount of light can be controlled uniformly. Accordingly, a preferred embodiment of the present invention can effectively reduce the number of light sources 211 arranged and reduce the spacing between light sources 211, thereby preventing the hot spot phenomenon from occurring. .

More specifically, referring to (a) of FIG. 7, according to the comparative example, in order to ensure uniformity of light amount from the central area of the light incident area to the edge, it is necessary to provide sufficient light to the edge of the light incident area. Therefore, it is necessary to arrange the light source 211 disposed at the edge in contact with the boundary of the light output area A/A or to overlap it. In this case, considering the beam angle of the light source 211 and considering that the spacing between the neighboring light sources 211 must be constant, a relatively large number of light sources 211 are required to sufficiently provide light to the light incident surface of the preset area. ) need to be placed.

In contrast, referring to (b) of FIG. 7, a preferred embodiment of the present invention can secure uniformity of light quantity in the light incident area by modifying the shape of the light source housing 330 to which the light leak blocking pad 340 is joined. there is. Accordingly, in a preferred embodiment of the present invention, in order to ensure uniformity of light quantity, there is no need to arrange the light source 211 disposed at the edge in contact with or overlapping the border of the light output area (A/A). It can be placed at a certain interval (G1) inward from the boundary of A/A). That is, in a preferred embodiment of the present invention, since the amount of light at the edge can be sufficiently compensated, light can be uniformly provided to the light incident surface of a preset area even with a relatively small number of light sources 211.

In addition, referring to (c) of FIG. 7, since the edge light source 221 can be placed inside the light emitting area, assuming the same number of light sources 211, the neighboring light sources 221 compared to the comparative example The separation distance (G2) between them can be reduced. Accordingly, it has the advantage of improving the hot spot phenomenon in the light incident area.

In other words, as the separation distance G1 between the light source 211 disposed at the edge and the boundary of the light output area A/A is sufficiently secured, the separation distance G2 between neighboring light sources 211 can be reduced. Accordingly, a preferred embodiment of the present invention controls the position of the boundary between the light source 211 disposed at the edge and the light exit area A/A, thereby ensuring uniformity of the amount of light provided from the light source in the light incident area and avoiding hot spots. It has the advantage of significantly improving the phenomenon.

Figure 8 is a diagram for explaining a preferred application example of a light source housing in which a light leak blocking pad is laminated.

Referring to FIG. 8 , the light source housing 330 to which the light leak blocking pad 340 is laminated has a shape 350 in which at least one edge is chamfered. The light source housing 330 to which the light leak blocking pad 340 is attached has at least one edge partially removed in the width direction.

In the area having the chamfered shape 350, since it is difficult to compensate for the amount of light by the neighboring light sources 211 toward the edge of the light incident portion, the amount of light provided may gradually decrease toward the edge of the light incident portion. Correspondingly, in the area having the chamfered shape 350, the width W of the light source housing 330 to which the light leak blocking pad 340 is joined can be set to gradually decrease toward the edge.

In a preferred embodiment of the present invention, the width of the light source housing 330 with the light leak blocking pad 340 is designed to gradually decrease toward the edge, thereby responding to the amount of light provided from the light source 211 depending on the position of the liquid crystal. The amount of light emitted from the panel can be effectively compensated to be uniform across the entire area.

Through the above-described content, those skilled in the art will be able to make various changes and modifications without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be determined by the scope of the patent claims.

100: liquid crystal panel 211: light source
213: light guide plate 310: cover bottom
320: Guide panel 330: Light source housing
340: Light leak blocking pad

Claims (9)

A backlight unit including a light guide plate having a light entrance surface, and a light source that irradiates light to the light entrance surface from a side of the light guide plate;
a light source housing covering the light source and an upper portion of the light receiving surface; and
It is interposed between the light source housing and the light guide plate and includes a light leak blocking pad attached to a lower portion of the light source housing,
At least one edge of the light source housing to which the light leak blocking pad is attached,
A liquid crystal display device having a chamfered shape.
According to claim 1,
The light source housing is,
It includes a first surface relatively adjacent to the light source and a second surface relatively spaced apart from the light source,
The chamfered shape is,
A liquid crystal display device formed on an edge of the second surface.
According to claim 1,
The light source housing is,
having a first width at the central region and a second width at the edges,
The first width is wider than the second width.
According to claim 1,
The width of the light source housing is,
A liquid crystal display device in which the area having the chamfered shape gradually decreases toward the edge.
According to claim 1,
a liquid crystal panel disposed on the backlight unit; and
It is disposed between the liquid crystal panel and the backlight unit, supports a lower part of the liquid crystal panel, and further includes a guide panel having a frame shape with a center pierced and partially open at the light receiving surface,
The light source disposed at one edge of the light sources is,
A liquid crystal display device disposed at a certain distance inward from a boundary of a light output area defined by a combination structure of the guide panel and the light source housing.
According to claim 1,
The light source housing is,
A liquid crystal display device comprising a white colored plastic material.
According to claim 1,
The light leak blocking pad is,
A liquid crystal display device that is black in color and made of single-sided tape or plastic.
According to claim 5,
Further comprising a cover bottom accommodating the backlight unit inside,
The cover bottom is,
It includes an upper support part, a side support part, and a lower support part formed by double bending at the light incident surface,
The light source housing is,
A liquid crystal display device interposed between the upper support portion and the light source and attached to the upper support portion with an adhesive member.
According to claim 8,
The light source is,
Accommodated in an internal space provided by a combination structure of the upper support part, the side support part, and the lower support part,
The liquid crystal panel is
A liquid crystal display device supported by the upper support portion at the light receiving surface.

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