KR102205131B1 - Back light unit and liquid crystal display device comprising the same - Google Patents

Abstract

The present invention provides a backlight unit capable of reducing the width of a bezel and a liquid crystal display including the same. A light guide plate including a reflective surface provided in the light guide plate, a reflective member provided on the outer surface of the light exit part and the reflective surface, and a light emitting diode array disposed to face a light incident side provided on the inner surface of the light input part.

Description

BACK LIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE COMPRISING THE SAME TECHNICAL FIELD

The present invention relates to a liquid crystal display device, and more particularly, to a backlight unit capable of reducing a bezel width and a liquid crystal display device including the same.

A typical liquid crystal display device displays an image using a thin film transistor as a switching element. Such liquid crystal display devices are widely used as display devices such as notebook computers, tablet computers, smart phones, portable display devices, and portable information devices, in addition to display devices of televisions or monitors. Since such a liquid crystal display is not a self-emission system, an image is displayed using light irradiated from a backlight unit disposed under the liquid crystal display panel.

1 is a cross-sectional view schematically showing a general backlight unit.

Referring to FIG. 1, a general backlight unit includes a light guide plate 10 having a light incident part 12, and a light emitting diode array disposed on one side of the light guide plate 10 so as to face the light incident part 12 of the light guide plate 10. It includes (20).

The light guide plate 10 internally refracts and reflects the light incident from the light emitting diode array 20 through the light incident part 12 to emit it toward the top surface.

The light emitting diode array 20 includes a plurality of light emitting diodes arranged at regular intervals to irradiate light to the light incident portion 12 of the light guide plate 10.

In such a general backlight unit, a hot spot phenomenon occurs in the light incident part 12 of the light guide plate 10 according to the pitch between the light emitting diodes disposed in the light emitting diode array 20. In order to improve the hot spot phenomenon, the light emitting diode array 20 must be spaced apart from the light incident part 12 of the light guide plate 10 by a certain level of optical distance OL, and thus, the width of the light incident part bezel of the backlight unit ( BW) increases.

Meanwhile, Korean Laid-Open Patent Publication No. 10-2008-0108753 (hereinafter referred to as “prior patent document”) discloses a light guide plate capable of miniaturizing the size of a liquid crystal display device, a backlight assembly including the same, and a liquid crystal display device. have.

2 is a cross-sectional view schematically showing a backlight assembly of the prior patent document.

Referring to FIG. 2, the backlight assembly of the prior patent document includes a light guide plate 50 and a light emitting diode array 60 disposed under one side of the light guide plate 50.

The light guide plate 50 shares the first plate 51 and the sidewall 53 of the first plate 51 and includes a second plate 55 provided in a lower part of the first plate 51, and the first plate A reflective member 57 is provided on the side wall 53 of the 51. The second plate 55 is bent downward from one side of the first plate 51 to extend parallel to the first plate 51 to cover a portion of the lower portion of the first plate 51. A light emitting diode array 60 is disposed on the end side of the second plate 55.

In such a backlight assembly of the prior patent document, the light emitted from the light emitting diode array 60 is uniformly mixed in the second plate 55, and the uniformly mixed light is a reflective member formed on the side wall 53 It is reflected by 57 and the path is changed to become more uniform, and is moved to the first plate 51 so that light is emitted to the upper surface of the first plate 51.

However, the backlight assembly of the prior patent document has the following problems.

First, since the light guide plate is separated into the first and second plates 51 and 55, an additional process of providing the second plate 55 is required, and the first and second plates 51 and 55 due to vibration/shock, etc. Cracks/scratches, etc. occur in the areas where) are in contact with each other, which causes luminance and image quality to deteriorate.

Second, since the side walls 53 shared by the first and second plates 51 and 55 protrude to the outside, the bezel width BW of the backlight unit increases due to a mechanism for covering the side walls 53. do.

The present invention has been devised to solve the above-described problem, and it is an object of the present invention to provide a backlight unit capable of reducing a bezel width and a liquid crystal display device including the same.

The backlight unit according to the present invention for achieving the above-described technical problem includes a light guide plate including a light incident part protruding from a lower surface of one edge of the light output part and a reflective surface provided on an outer surface of the light input part, an outer surface of the light output part and the A reflective member provided on a reflective surface, and a light emitting diode array disposed to face a light-incident side provided on an inner surface of the light-incident portion may be included.

A liquid crystal display device according to the present invention for achieving the above-described technical problem includes a backlight unit and a liquid crystal display panel that displays an image using light irradiated from the backlight unit, and the backlight unit includes a light emitting unit A light guide plate including a light incidence part protruding from the lower surface of one edge and a reflective surface provided on an outer surface of the light incidence part, an outer surface of the light-exiting part and a reflective member provided on the reflective surface, and a light-incident side surface provided on the inner surface of the light-incident part It may include a light emitting diode array disposed to face the.

According to the means for solving the above problems, the present invention can reduce the width of the bezel by the size of the LED array compared to the general edge type backlight unit. In particular, the present invention does not require an additional process of providing a light-incident portion compared to prior patent documents, and because the outer surface of one side of the light-exiting portion does not protrude to the outside, the bezel width of the backlight unit can be reduced, It is possible to prevent a decrease in luminance and image quality due to a split/scratch between the light-exiting part and the light-incoming part due to impact or the like.

In addition to the effects of the present invention mentioned above, other features and advantages of the present invention will be described below or will be clearly understood by those of ordinary skill in the art from such technology and description.

1 is a cross-sectional view schematically showing a general backlight unit.
2 is a cross-sectional view schematically showing a backlight assembly of the prior patent document.
3 is a schematic cross-sectional view of a backlight unit according to an embodiment of the present invention.
4 is a cross-sectional view illustrating an edge of one side of the light guide plate shown in FIG. 3.
5 is a perspective view showing the light guide plate shown in FIG. 3.
6 is a perspective view illustrating a light emitting diode array disposed on a light incident side of the light guide plate shown in FIG. 3.
7 is a graph showing a simulation result of a total reflection light amount ratio for each distance apart from LEDs in the light guide plate according to the present invention.
8 is a graph showing a simulation result of a total reflection light amount ratio for each reflective surface angle of the light guide plate in the light guide plate according to the present invention.
9 is a graph showing a simulation result of a total reflection light amount ratio for each thickness of a light guide plate exit portion in the light guide plate according to the present invention.
10 is a graph showing a simulation result of a total reflection light amount ratio for each thickness of a light guide plate incident portion in the light guide plate according to the present invention.
11 is a graph showing a simulation result of the total reflection efficiency of the light-incident portion of the light guide plate according to the exemplary embodiment, the reference example, and the comparative examples 1 to 7 of the present invention.
12 is a perspective view schematically illustrating a liquid crystal display according to an exemplary embodiment of the present invention.
FIG. 13 is a schematic cross-sectional view of a cross section taken along line II' shown in FIG. 12.

The meaning of the terms described in this specification should be understood as follows.

Singular expressions should be understood as including plural expressions unless clearly defined differently in context, and terms such as "first" and "second" are used to distinguish one element from other elements, The scope of rights should not be limited by these terms. It is to be understood that terms such as "comprise" or "have" do not preclude the presence or addition of one or more other features or numbers, steps, actions, components, parts, or combinations thereof. The term “at least one” is to be understood as including all possible combinations from one or more related items. For example, the meaning of “at least one of the first item, the second item, and the third item” means 2 among the first item, the second item, and the third item as well as each of the first item, the second item, or the third item. It means a combination of all items that can be presented from more than one. The term "on" is meant to include not only a case where a certain structure is formed directly on the top surface of another structure, but also a case where a third structure is interposed between these elements.

Hereinafter, preferred examples of a backlight unit and a liquid crystal display including the same according to the present invention will be described in detail with reference to the accompanying drawings. In adding reference numerals to elements of each drawing, the same elements may have the same numerals as possible even if they are indicated on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the subject matter of the present invention, a detailed description thereof may be omitted.

3 is a cross-sectional view schematically illustrating a backlight unit according to an exemplary embodiment of the present invention, FIG. 4 is a cross-sectional view illustrating an edge of the light guide plate shown in FIG. 3, and FIG. 5 is a perspective view illustrating the light guide plate shown in FIG. 3. , FIG. 6 is a perspective view showing a light emitting diode array disposed on a light incident side of the light guide plate shown in FIG. 3.

3 to 6, the backlight unit 100 according to an exemplary embodiment of the present invention includes a light guide plate 110, a reflective member 120, and a light emitting diode array 130.

The light guide plate 110 internally refracts and reflects light incident from the light emitting diode array 130 to emit light toward the top surface. To this end, the light guide plate 110 according to an example includes a light exit unit 111, a light incident unit 113, and a reflective surface 115.

The light exit part 111 is provided in the form of a flat plate having a first thickness t1, and has one outer surface 111a and the other outer surface 111b based on the length direction X of the light guide plate 110 In addition, a light exit surface 111c and a rear surface 111d are provided based on the thickness direction Z of the light guide plate 110. The light-exiting part 111 is polymethyl methacrylate (PMMA), acrylonitrile styrene (AS), polystyrene (PS), polycarbonate (PC), polyethersulfone ( It may be made of any one material selected from polyethersulfone (PES), polyamide (PA), polyesterimide (PEI), and polymethylpentene (PMP).

Additionally, an optical pattern 112 is provided on the upper and/or lower surfaces of the light-exiting part 111 to scatter the total reflection of light that is totally reflected inside the light-exiting part 111 to emit light to the upper part of the light-exiting surface 111c. .

The light-incident part 113 protrudes from the lower surface of the edge part EP of one side of the light-exit part 111 to a certain length L and a certain thickness t2. In some cases, the light-incident portion 113 may protrude to have a length L greater than or equal to the thickness t1 of the light-exiting portion 111 and a thickness t2 that is thinner than the thickness t1 of the light-exiting portion 111. For example, a thickness ratio (t1/t2) between the thickness t1 of the light exit part 111 and the thickness t2 of the light incident part 113 may be set to 1.25 times or more.

The inner surface of the light-incident portion 113 is stepped by a second thickness t2 from the lower surface 111d of the light-exit portion 111 to serve as a light-incident side surface 113a. Here, the length (L) of the light-incident portion 113 is defined as the distance between the one side outer surface 111a of the light-guide plate 110 and the light-incident side 113a based on the length direction X of the light guide plate 110 (Or the LED separation distance to be described later) is set in the range of i to 4i from the outer side 111a of the light guide plate 110 (wherein i is the thickness t1 of the light exit part 111, and the unit is mm). I can. The light-incident side surface 113a is concealed without being exposed to the outer surface of the light guide plate 111 by the edge portion EP of the light-exiting part 111 and the light-incident part 113. In addition, since the light-incident portion 113 protrudes from the light-exit portion 111 in the lower surface direction of the light-exit portion 111 to have a predetermined thickness, the length of the light-exit portion 111 is not changed.

As such, the light-incident portion 113 is formed integrally with the light-exiting portion 111 by an injection method using a mold, so that the present invention does not require an additional process for forming the light-incident portion 113.

The reflective surface 115 is provided to be inclined at an angle θ on the outer surface of the light incident part 113. The angle θ of the reflective surface 115 according to an example is an outer surface 111a of one side of the light guide plate 110 so that straight light incident through the light-incident part 113 is regularly reflected into the light-exiting part 111 It may be set in the range of 2 degrees to 12 degrees as the reference (RL). At this time, the reflective surface 115 is inclined from the lower surface of the light-incident portion 113 spaced apart from one outer surface 111a of the light-exit portion 111 to the lower surface of one outer surface 111a of the light-exit portion 111 Therefore, the height H of the reflective surface 115 is the same as the thickness t2 of the light incident part 113. Accordingly, the reflective surface 115 is formed in an isosceles triangular shape with the thickness t2 of the light incident part 113 as the base.

The reflective member 120 is provided on an outer surface of one side of the light guide plate 110 to specularly reflect (or mirror-reflect) light incident from the light-incident part 113 to the interior of the light-exiting part 111. Here, the reflective member 120 may be attached to the one side outer surface 111a and the reflective surface 115 of the light exit part 111 by an adhesive member such as OCA (optical clear adhesive) or OCR (optical clear resin). have.

The reflective member 120 according to the first example may be a reflective plate made of aluminum (Al) or nickel (Ni). Additionally, the reflective member 120 according to the first example may further include a reflective sheet attached to the reflective plate to prevent loss of light absorbed by the reflective plate.

The reflective member 120 according to the second example may be a specular reflection mirror.

The reflective member 120 according to the first and second examples includes a vertical reflecting part 121 provided on one outer surface 111a of the light emitting part 111 and an oblique reflecting part 123 provided on the reflecting surface 115. ).

The vertical reflecting part 121 is provided perpendicular to the one side outer surface 111a of the light-exiting part 111, and receives light incident from the light-incident part 113 to the one-side outer surface 111a of the light-emitting part 111 The loss of light leaking to the outside through the one side outer surface 111a of the light emitting part 111 is prevented by reflecting it in the light emitting part 111.

The inclined reflective part 123 is provided to be inclined on the reflective surface 115, and by regularly reflecting straight light incident from the light incident part 113 to the reflective surface 115 into the interior of the light emitting part 111, the reflective surface 115 ) To prevent loss of light leaking to the outside.

The LED array 130 includes a light source array substrate 131 and a plurality of LED packages 133.

The light source array substrate 131 is disposed to face the light incident side 113a provided on the light incident part 113 of the light guide plate 110. The light source array board 131 is a metal printed circuit board including a driving power line (not shown) for supplying light source driving power to each of the plurality of LED packages 133 and a connector (not shown) connected to the driving power line. Alternatively, it may be a flexible printed circuit board. The light source array substrate 131 is connected to a backlight driving circuit through a signal cable (not shown) connected to a connector to transmit light source driving power supplied from the backlight driving circuit to the plurality of LED packages 113. Additionally, a reflective coating layer 132 may be provided on the inner side of the light source array substrate 131 facing the light incident side 113a of the light incident part 113, and the reflective coating layer 132 may be formed on the light incident side 113a. ) To prevent the loss of light absorbed by the light source array substrate 131 by re-inciding the incident light to the light incident side surface 113a.

Each of the plurality of LED packages 133 is mounted on the light source array substrate 131 at regular intervals to face the light incident side surface 113a of the light incident unit 113. Each of the plurality of LED packages 133 emit light according to the light source driving power supplied from the light source array substrate 131 to irradiate light onto the light incident side 113a of the light incident unit 113. Each of the plurality of light emitting diode packages 133 according to an example may be a point light source composed of a single light emitting diode driving chip or a linear light source having a plurality of light emitting diode driving chips.

The light emitted from the light emitting diode array 130 is incident on the light incident side 113a provided on the light incident part 113 of the light guide plate 110. The light incident on the light-incident portion 113 of the light guide plate 110 is totally reflected in the light-incident portion 113 and proceeds toward the reflective surface 115 and one outer surface 111a of the light-exiting portion 111 to the reflective member 120 ) Is totally reflected. The light totally reflected by the reflective member 120 proceeds to the inside of the light exit part 111 and passes through refraction and total reflection in the light exit part 111 through the light exit surface 111c of the light exit part 111. Light is emitted from the top of the light guide plate 110. At this time, the light emitted from the light emitting diode array 130 proceeds by a distance corresponding to the length L of the light incident unit 113 and then proceeds to the interior of the light emission unit 111 by the reflective member 115. A hot spot phenomenon occurring according to a pitch between the diode packages 133 may be prevented.

Additionally, the backlight unit 100 according to an embodiment of the present invention further includes a light source housing 140, a reflective sheet 150, and an optical sheet unit 160.

The light source housing 140 supports the light-incident part 113 of the light guide plate 110 while supporting the light emitting diode array 130. The light source housing 140 also serves to reflect light incident through the lower surface of the light-incident portion 113 of the light guide plate 110 to the light-incident portion 113 and to dissipate heat generated from the light-emitting diode array 130. To this end, the light source housing 140 according to an example may be made of a metal material such as aluminum (Al) material or nickel (Ni) material having an “L” shape.

The reflective sheet 150 is disposed on the lower surface of the light exit part 111 of the light guide plate 110 except for the light incident part 113 of the light guide plate 110. The reflective sheet 150 reflects light incident through the lower surface of the light exit part 111 of the light guide plate 110 into the light exit part 111 of the light guide plate 110 to minimize loss of light.

The optical sheet unit 160 is disposed on the upper surface of the light guide plate 110 to improve luminance characteristics of light emitted from the light guide plate 110. The optical sheet unit 160 according to an example may be formed of at least two of a diffusion sheet, a light collecting sheet, and a reflective polarizing sheet, or a combination thereof.

As described above, the backlight unit 100 according to an exemplary embodiment of the present invention transmits light incident from the light emitting diode array 130 through the light incident part 113 protruding from the edge portion EP of the light guide plate 110. Light is emitted through the light exit surface 111c of the light guide plate 110. Accordingly, according to the present invention, the width of the bezel may be reduced by the size of the LED array 130 compared to the general edge type backlight unit. In particular, the present invention does not require an additional process of providing the light-incident portion 113 compared to the prior patent document, and the light-incident portion 113 does not protrude outward from one side of the light-exiting portion 111. It is possible to reduce the width of the bezel of the unit, and it is possible to prevent a decrease in luminance and image quality due to a split/scratch between the light emitting part 111 and the light receiving part 113 due to vibration/shock.

7 is a graph showing a simulation result of a total reflection light amount ratio for each distance apart from LEDs in the light guide plate according to the present invention.

Referring to FIG. 7 with FIG. 4, the simulation result of FIG. 7 shows the light guide plate 110 having a thickness t1 of 2.0 mm and a thickness t2 of the light incident part 113 of 0.9 mm. This is a measurement of the total reflection light intensity ratio by LED separation distance. In FIG. 7, the distance between the LEDs refers to the distance between the light guide plate 110 and the light emitting diode from one outer surface 111a of the light guide plate 110, and the total reflection amount ratio for each distance between the LEDs is the light output part of the light guide plate 110. (111) It means a value obtained by dividing the total reflection luminous flux lm incident into the interior by the total reflection luminous flux lm incident on the light incident part of the general light guide plate shown in FIG. 1.

As can be seen from FIG. 7, when the LED separation distance is in the range of 2.5mm to 8mm, the light guide plate 110 according to the present invention has a total reflection luminous flux of 80% or more compared to a general light guide plate. In particular, when the LED separation distance of the light guide plate 110 according to the present invention is 3.5 mm, it can be seen that the total reflection luminous flux is at a level of 90% compared to a general light guide plate.

Therefore, in the light guide plate 110 of the present invention, the LED separation distance may be set in the range of 2.5mm to 8mm, and it is preferable that the LED separation distance is set to 3.5mm in order to implement a high-brightness backlight. As a result, the distance between the LEDs is preferably set in a range from i to 4i (wherein i is the thickness (t1) of the light emitting part 111, and the unit is mm) from the outer surface 111a of one side of the light guide plate 110 .

8 is a graph showing a simulation result of a total reflection light amount ratio for each reflective surface angle of the light guide plate in the light guide plate according to the present invention.

Referring to FIG. 8 with FIG. 4, the simulation result of FIG. 8 shows that the thickness t1 of the light emitting part 111 is 2.0 mm, the thickness t2 of the light incident part 113 is 0.9 mm, and the LED separation distance is 3.5 mm. This is a measurement of the total reflection light amount ratio for each angle θ of the reflective surface 115 with respect to the phosphor light guide plate 110. In FIG. 8, the angle θ of the reflective surface 115 refers to an angle from the lower surface of the outer surface 111a of one side of the light guide plate 110.

As can be seen from FIG. 8, in the light guide plate 110 according to the present invention, when the angle θ of the reflective surface 115 is in the range of 2° to 12°, it can be seen that the total reflection luminous flux is at least 80% of the general light guide plate. . Particularly, in the light guide plate 110 according to the present invention, when the angle θ of the reflective surface 115 is 8°, it can be seen that the total reflection luminous flux is at a level of 90% compared to a general light guide plate.

Therefore, in the light guide plate 110 of the present invention, the angle θ of the reflective surface 115 may be set in the range of 2° to 12°, and the reflective surface 115 is It is preferable that the angle θ is set to 8°.

9 is a graph showing a simulation result of a total reflection light amount ratio for each thickness of a light guide plate exit portion in the light guide plate according to the present invention.

Referring to FIG. 9 with FIG. 4, the simulation result of FIG. 9 shows that the thickness t2 of the light incident part 113 is 0.9 mm, the distance between the LEDs is 3.5 mm, and the angle θ of the reflective surface 115 is 8°. The total reflection light quantity ratio for each thickness t1 of the light exit part 111 is measured for the phosphor light guide plate 110.

As can be seen from FIG. 9, when the thickness t1 of the light-exiting part 111 is 1.5 mm or more, the light guide plate 110 according to the present invention has a total reflection luminous flux of 80% or more compared to a general light guide plate. In particular, in the light guide plate 110 according to the present invention, when the thickness t1 of the light exit part 111 is 2 mm, the total reflection luminous flux is at least 90% of that of a general light guide plate, and the thickness t1 of the light exit part 111 is 3 mm or more. At this time, it can be seen that the total reflection luminous flux is saturated to 92% of the general light guide plate.

Therefore, in the light guide plate 110 of the present invention, the thickness t1 of the light exit part 111 may be set to 1.5 mm or more, and it is preferable that the LED separation distance is set to 3 mm or more in order to implement a high brightness backlight lunnet. .

10 is a graph showing a simulation result of a total reflection light amount ratio for each thickness of a light guide plate incident portion in the light guide plate according to the present invention.

Referring to FIG. 10 with FIG. 4, the simulation result of FIG. 10 shows that the thickness t1 of the light emitting part 111 is 2.0 mm, the distance between the LEDs is 3.5 mm, and the angle θ of the reflective surface 115 is 8°. The total reflection light quantity ratio for each thickness t2 of the light incident part 113 is measured for the phosphor light guide plate 110.

As can be seen from FIG. 10, when the thickness t2 of the light incident part 113 is 1.2 mm or less in the light guide plate 110 according to the present invention, it can be seen that the total reflection luminous flux is at least 80% of the general light guide plate. In particular, in the light guide plate 110 according to the present invention, when the thickness t2 of the light incident part 113 is 0.9 mm, the total reflection luminous flux is at least 90% of that of a general light guide plate, and the thickness t2 of the light incident part 113 is 0.4 In mm, it can be seen that the total reflection luminous flux is improved to a level of 97% compared to a general light guide plate.

Accordingly, in the light guide plate 110 of the present invention, the thickness t2 of the light incident part 113 may be set to 1.2 mm or less, and it is preferable that the LED separation distance is set to 0.9 mm or less in order to implement a high-bright backlight lunnet. Do.

As a result, according to the simulation results of FIGS. 9 and 10, the thickness ratio (t1/t2) of the light-exiting part 111 and the light-incident part 113 in the light guide plate 110 may be set to 1.25 times or more, and a high-luminance backlight In order to implement the yunnet, the thickness ratio (t1/t2) of the light emitting part 111 and the light receiving part 113 is preferably set to 1.5 times or more.

11 is a graph showing a simulation result of the total reflection efficiency of a light-incident portion for each of the light guide plates in the embodiment, the reference example, and the comparative examples 1 to 7 of the present invention.

In FIG. 11, in the embodiment, the thickness t1 of the light emitting part 111 is 2.0 mm, the distance between the LEDs is 3.5 mm, the angle θ of the reflective surface 115 is 8°, and the thickness of the light incident part 113 This is the simulation result for the light guide plate in which (t2) is set to 0.4mm. A reference example is a simulation result for the general light guide plate shown in FIG. 1. Comparative Example 1 is the light guide plate shown in Fig. 3 of the prior patent document, and Comparative Examples 2 to 4 have sidewall inclinations of 30°, 45°, and 60°, respectively, of the first and second plates shown in Fig. 5 of the prior patent document. Phosphorus light guide plate, Comparative Examples 5 to 7 are simulation results for each of the light guide plates having sidewall inclinations of 30°, 45°, and 60°, respectively, of the first and second plates shown in FIG. 6 of the prior patent document.

As can be seen from FIG. 11, it can be seen that the light guide plate according to the embodiment of the present invention has a total reflection light quantity ratio of 97.5% compared to the light guide plate of the reference example. That is, in the light guide plate according to an embodiment of the present invention, an inclined reflective surface is provided on an outer surface of one side of the light-incident portion, and an outer surface of one side of the light-exiting portion is provided as a vertical surface. Accordingly, in the light guide plate according to an embodiment of the present invention, straight light incident from the light incident part by the inclined reflective surface is totally reflected into the light exit part, and is incident from the light incident part at a certain angle of incidence by one outer surface of the light exit part. The light is totally reflected inside the light-exiting part, and in particular, as in the graph of FIG. 10, as the thickness of the light-incident part increases, the amount of total reflection light incident into the light-exiting part increases and the total reflection efficiency is improved. You can see what you have.

On the other hand, it can be seen that each of Comparative Examples 1 to 7 has a total reflection light quantity ratio of 71% or less compared to the light guide plate of the reference example. That is, in each of Comparative Examples 1 to 7, the sidewalls of each of the first and second plates are rounded or inclined, and the first and second plates have the same thickness. Accordingly, in each of Comparative Examples 1 to 7, the light reflected by the reflective member is directly emitted not only to the inside of the first plate, but also directly to the upper surface of the first plate overlapping the second plate, or is reflected back to the second plate to be 2 It can be seen that the total reflection light incident on the first plate decreases as the light exits the lower surface of the plate, thereby reducing the total reflection efficiency.

As a result, it can be seen that the light guide plate 110 according to the present invention has a significantly higher total reflection efficiency than the light guide plate of the prior patent document.

12 is a perspective view schematically illustrating a liquid crystal display device according to an exemplary embodiment of the present invention, and FIG. 13 is a cross-sectional view schematically illustrating a cross section taken along line II′ of FIG. 12.

12 and 13, a liquid crystal display device 200 according to an exemplary embodiment of the present invention includes a liquid crystal display panel 210, a backlight unit 220, a lower case 230, a guide frame 240, and a panel. It includes a driving unit 250, a rear cover 260, and a front partial cover 270.

The liquid crystal display panel 210 is composed of a lower substrate 212 and an upper substrate 214 opposingly bonded with a liquid crystal layer therebetween, and displays a predetermined image using light irradiated from the backlight unit 220 do.

The lower substrate 212 is a thin film transistor array substrate, and includes a display area comprising a plurality of pixels (not shown) formed for each pixel area intersected by a plurality of gate lines (not shown) and a plurality of data lines (not shown). AA). Each pixel may include a thin film transistor (not shown) connected to a gate line and a data line, a pixel electrode connected to the thin film transistor, and a common electrode formed adjacent to the pixel electrode to which a common voltage is supplied.

A pad portion (not shown) connected to each signal line is provided at a first side edge portion of the lower substrate 212, and the pad portion is connected to the panel driver 250. In addition, a gate drive for supplying a gate (or scan) signal to a gate line of the liquid crystal display panel 1100 in a second edge portion of the lower substrate 212 or a non-display area of the second and third edge portions A circuit (not shown) is formed. The gate driving circuit is formed together with the thin film transistor manufacturing process of each pixel so as to be connected to each gate line.

The upper substrate 214 includes a pixel defining pattern defining an opening region overlapping each pixel region formed on the lower substrate 212 and a color filter formed in the opening region. The substrate 113 is substantially bonded to the lower substrate 212 with a liquid crystal layer therebetween. Additionally, the upper substrate 214 may further include a common electrode overlapping with the pixel electrode formed on the lower substrate 212 with a liquid crystal layer therebetween. In this case, the lower substrate 212 The provided common electrode is omitted.

The liquid crystal layer is interposed between the lower substrate 212 and the upper substrate 214, and liquid crystal molecules are formed according to a data voltage applied to each pixel electrode and a horizontal electric field (or vertical electric field) formed by a common voltage. It may be formed of liquid crystals arranged in a horizontal (or vertical) direction.

A lower polarizing film 216 having a first polarization axis is attached to the rear surface of the lower substrate 212, and an upper polarizing film 218 having a second polarization axis crossing the first polarization axis is attached to the upper surface of the upper substrate 214. ) Is attached.

The backlight unit 220 is disposed under the liquid crystal display panel 210 to irradiate light onto the rear surface of the liquid crystal display panel 210. The backlight unit 220 includes a light guide plate 110, a reflective member 120, and a light emitting diode array 130. In addition, the backlight unit 220 further includes a light source housing 140, a reflective sheet 150, and an optical sheet unit 160. Since the backlight unit 220 is the same as the backlight unit 100 described above with reference to FIGS. 3 to 11, a redundant description thereof will be omitted. As shown in FIG. 4, the backlight unit 220 transmits light incident on the light incident part 113 of the light guide plate 110 from the light emitting diode array 130 to the reflective surface 115 and the reflective member ( Through 120 ), the liquid crystal display panel 210 is specularly reflected to the display area AA. Accordingly, according to the present invention, the light emitting diode array 130 is disposed under the light guide plate 110 corresponding to the lower edge of one side of the light guide plate 110 or the display area AA of the liquid crystal display panel 210. The bezel width BW of the liquid crystal display 200 may be reduced by the size of 130.

The lower case 230 is formed to have a storage space to accommodate the backlight unit 220 and supports the guide frame 240. The lower case 230 according to an example is bent vertically from the bottom surface supporting the light source housing 140 and the reflective sheet 150 of the backlight unit 220 and the end of the bottom surface to form the guide frame 240. It may include a supporting case sidewall. The lower case 230 may be made of a metal material or engineering plastic material having high thermal conductivity for dissipating heat generated from the light emitting diode array 130.

The guide frame 240 is formed in the shape of a square band to support an edge portion of the rear surface of the liquid crystal display panel 110. The guide frame 240 includes a panel support portion supporting a rear edge portion of the liquid crystal display panel 210, and a guide sidewall formed perpendicularly from the panel support portion to surround each side of the lower case 230. Here, the panel support portion of the guide frame 240 may be physically bonded to the rear edge of the liquid crystal display panel 210 through an adhesive member 245 such as a double-sided tape, a thermosetting resin, or a photocurable resin.

The panel driver 250 is connected to a pad portion provided on the lower substrate 212 to drive each pixel of the liquid crystal display panel 210 to display a predetermined color image on the liquid crystal display panel 210. The panel driver 250 according to an example includes a plurality of circuit films 252 connected to a pad portion of the liquid crystal display panel 210, a data driving integrated circuit 254 mounted on each of the plurality of circuit films 252, and a plurality of It is configured to include a printed circuit board 256 bonded to each of the circuit films 252.

Each of the plurality of circuit films 252 is attached to the pad portion of the lower substrate 212 and the printed circuit board 256 by a film attaching process, and is a tape carrier package (TCP) or a chip on flexible board or chip (COF). On Film). Each of the plurality of circuit films 252 may be disposed on the side of the guide frame 240, or may be bent toward the rear side of the rear case 230 so as to surround the side of the guide frame 240.

The data driving integrated circuit 254 is mounted on each of the plurality of circuit films 252. The data driving integrated circuit 254 receives a data control signal from pixel data supplied from the outside, converts the pixel data into an analog data signal according to the data control signal, and supplies it to the data line of the lower substrate 212. .

The printed circuit board 256 is connected to a plurality of circuit films 252. The printed circuit board 256 serves to provide a signal required to display an image in each pixel of the liquid crystal display panel 210 to the data driving integrated circuit 254 and the gate driving circuit. To this end, a timing controller (not shown), various signal wirings, various power circuits (not shown), and memory devices (not shown) are mounted on the printed circuit board 256.

The timing control unit is mounted on the printed circuit board 256 and transmits digital image data input from the driving system to the pixel arrangement structure of the liquid crystal display panel 210 in response to a timing synchronization signal supplied from an external driving system (not shown). The pixel data for each pixel is properly aligned, and the generated pixel data for each pixel is provided to the data driving integrated circuit 254. Further, the timing controller generates a data control signal and a gate control signal respectively based on the timing synchronization signal to control driving timings of the data driving integrated circuit 254 and the gate driving circuit.

In addition, the timing controller controls the luminance of light irradiated to the liquid crystal display panel 210 by controlling the LED array 130 of the backlight unit 220 through a backlight driver (not shown). In particular, the timing controller controls the luminance of the liquid crystal display panel 210 for each region through a local dimming technique. For example, the timing controller divides the display area AA of the liquid crystal display panel 210 into a plurality of horizontal dimming areas, and analyzes the pixel data for each pixel of the pixels included in each horizontal dimming area for each area. Local dimming data is calculated, and light emission of the LED array 130 is controlled for each area according to the calculated local dimming data for each area to individually control the luminance of each area of the liquid crystal display panel 210. Here, the local dimming data for each area may be an average grayscale value for each horizontal dimming area or a grayscale value having a maximum frequency.

The rear cover 260 constitutes the outermost rear and side surfaces of the liquid crystal display 200, and supports the rear surface of the lower case 230 while supporting the guide frame 240 and each side surface of the liquid crystal display panel 210. Surround To this end, the rear cover 260 is bent vertically from the cover plate supporting the rear surface of the lower case 230 and the end of the cover plate to surround the guide frame 240 and each side of the liquid crystal display panel 210. Includes cover sidewalls. Here, the upper portion of the cover sidewall surrounds each side surface of the liquid crystal display panel 210 excluding the front surface of the liquid crystal display panel 210 to cover the entire front surface of the liquid crystal display panel 210. 200).

Additionally, since the second to fourth side edges of the liquid crystal display panel 210 connected to the panel driver 250 are not covered by a separate device, the liquid crystal display panel 210 A side sealing member (not shown) having a predetermined thickness may be additionally provided on the second to fourth side surfaces of the liquid crystal display panel 210 for light leakage and side protection generated from the second to fourth sides of the liquid crystal display panel 210. The side sealing member may be formed of a thermosetting or photocurable resin, and may be formed through a coating process in which a predetermined thickness is applied to the second to fourth sides of the liquid crystal display panel 210 and a curing process performed immediately after the coating process.

The front partial cover 270 is assembled with the rear cover 260 to cover the first side edge portion of the liquid crystal display panel 210. That is, the pad part of the liquid crystal display panel 210 connected to the panel driver 250 is exposed in front of the liquid crystal display 200 without being covered by the rear cover 260. The front part cover 270 is assembled to the rear cover 260 so as to cover the first side edge of the liquid crystal display panel 210, the pad part, the panel driver 250, and the cover sidewall of the rear cover 260. The pad portion of the liquid crystal display panel 210 and the panel driver 250 are prevented from being exposed in front of the liquid crystal display device 200. Accordingly, according to the present invention, the width of the first side edge portion of the light guide plate decreases as the light emitting diode array is disposed under the light guide plate, so that the front portion cover 270 covers the first side edge portion of the liquid crystal display panel 210. The width BW may be reduced, and through this, the bezel width BW of the liquid crystal display may be reduced. In addition, in the present invention, the front surface of the liquid crystal display panel 210 except for the first side edge portion of the liquid crystal display panel 210 covered by the front part cover 270 is implemented in a plane without a step difference. The aesthetics of the liquid crystal display device can be improved.

As described above, in the liquid crystal display according to the present invention, the light emitting diode array 130 corresponds to the lower surface of one edge of the light guide plate 110 or the lower portion of the light guide plate 110 corresponding to the display area AA of the liquid crystal display panel 210. By being disposed in the light-emitting diode array 130, the light-incident bezel width BW is reduced. In addition, in the liquid crystal display according to the present invention, since the second to fourth edge portions other than the first edge portion of the liquid crystal display panel 210 are not covered by a separate device, the liquid crystal display panel 210 The second to fourth side edge portions have a thin bezel width corresponding to the thickness of the rear cover 260.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and that various substitutions, modifications, and changes are possible within the scope of the technical matters of the present invention. It will be obvious to those who have the knowledge of. Therefore, the scope of the present invention is indicated by the claims to be described later, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

100, 220: backlight unit 110: light guide plate
111: light emitting unit 113: light receiving unit
113a: light incident side 115: reflective surface
120: reflective member 130: light emitting diode array
140: light source housing 150: reflective sheet
160: optical sheet part 200: liquid crystal display
210: liquid crystal display panel 230: lower case
240: guide frame 250: panel driving unit
260: rear cover 270: front part cover

Claims (10)

A light guide plate including a light-exiting portion, a light-incident portion protruding from a lower surface of one edge of the light-exiting portion, and a reflective surface provided on an outer surface of the light-incident portion so as to be inclined from an outer surface of one side of the light-exiting portion;
A reflective member provided on an outer surface of one side of the light exit and the reflective surface; And
And a light emitting diode array disposed to face a light-incident side provided on an inner side of the light-incident portion and covered by the light-exiting portion,
One outer surface of the light exit part is a vertical surface having a length corresponding to the thickness of the light exit part,
The angle of the reflective surface is 2 degrees to 12 degrees based on the outer surface of one side of the light exit part,
The height of the reflective surface is the same as the thickness of the light incident part, the backlight unit. The method of claim 1,
The thickness of the light-incident portion is thinner than that of the light-exiting portion. The method of claim 2,
The thickness of the light-exiting portion is 1.25 times or more thicker than the thickness of the light-incident portion, the backlight unit. The method of claim 2,
The backlight unit, wherein the distance between the outer surface of one side of the light-exiting part and the light-incident side of the light-incident part is i to 4i (wherein i is the thickness of the light-exiting part, and the unit is mm). delete delete The method of claim 2,
The reflective member,
A vertical reflection part provided on an outer surface of one side of the light exit part; And
A backlight unit comprising an oblique reflective portion provided on the reflective surface. The method of claim 2,
A light source housing supporting the light incident part while supporting the light emitting diode array; And
A backlight unit further comprising a reflective sheet disposed on a rear surface of the light-exiting part except for the light-incident part. The backlight unit according to any one of claims 1 to 4, 7 and 8;
A liquid crystal display panel that displays an image using light irradiated from the backlight unit;
A guide frame supporting the liquid crystal display panel;
A lower case accommodating the backlight unit and supporting the guide frame; And
And a rear cover supporting the lower case and surrounding a side surface of the guide frame and the liquid crystal display panel. The method of claim 9,
A panel driver connected to one edge of the liquid crystal display panel and disposed between the guide frame and the rear cover; And
Further comprising a front part cover covering only one edge of the liquid crystal display panel connected to the panel driver,
The rear cover surrounds each side surface of the liquid crystal display panel except for a front surface of the liquid crystal display panel.

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