KR20170031979A - Backlight Unit And Liquid Crystal Display Device Using The Same - Google Patents

Abstract

The present invention relates to a backlight unit and a liquid crystal display device using the same. In the backlight unit including a lower cover, a light guide plate, and a light source, a supporting part is disposed on the back surface of the light guide plate so that the lower cover faces a side where the light source is not disposed. So, an optimum optical distance can be maintained between the light guide plate and the light source. Thus, it is possible to maintain the optimum optical distance between the light guide plate and the light source without the generation of light leakage or a dark part.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE USING THE SAME

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a backlight unit capable of maintaining a constant optical gap between a light source of a sidelight type and a light guide plate to prevent light leakage, and a liquid crystal display using the same.

In recent years, the display field has been rapidly developed in line with the information age, and as a flat panel display device (FPD) having the advantages of thinning, light weight, and low power consumption in response to this, a plasma display panel (PDP), an electroluminescence display device (ELD), a field emission display device (FED) ray tube (CRT).

Among these, liquid crystal display devices are excellent in moving picture display and are most actively used in the fields of notebooks, monitors, and televisions due to their high contrast ratio. Liquid crystal display devices have no self-luminous elements, .

Accordingly, a backlight unit having a light source is provided on the back surface of the liquid crystal panel, and light is emitted toward the front surface of the liquid crystal panel, thereby realizing an image of brightness that can be recognized only through the backlight unit.

Meanwhile, a general backlight unit is divided into a side light type and a direct type type according to the arrangement structure of the light sources. In the sidelight type, one or a pair of light sources are disposed on one side of the light guide plate Or two or two pairs of light sources are disposed on both side surfaces of the light guide plate, and the direct type type has a structure in which several light sources are disposed under the optical sheet.

Here, the sidelight method is advantageous in that it is easier to manufacture than the direct-type method, and is thinner than the direct-type type, has a light weight, and has low power consumption.

1 is a view schematically showing the structure of a backlight unit of a sidelight type in a conventional liquid crystal display device. As shown in the drawing, a conventional backlight unit 1 for a liquid crystal display comprises a light source and a plurality of optical members.

The light source 20 includes a plurality of point light sources, for example, a light emitting diode (LED) 21 and a printed circuit board 22 to which the light emitting diode 21 is bonded, A diffusing and prism sheet 70 for collecting and diffusing light that is guided by the light guide plate 30 and outgoing to the upper side and a diffusing and prism sheet 70 for emitting light to the back side of the light guide plate 30, And reflects light toward the light guide plate 30 again.

The backlight unit 1 is modularized by being coupled with the liquid crystal panel by various mechanical structures. In the case of a liquid crystal display module applied to a product, in order to prevent breakage of internal components due to flow, Since the light efficiency of the light emitted from the light source 20 depends on the distance between the light source 20 and the light incident surface of the light guide plate 30, the light incident surfaces of the light source 20 and the light guide plate 30 are aligned with each other and it is required to maintain the optimum optical distance.

 To this end, a separate fixing member is inserted between the light guide plate 30 and the lower cover 10 and fixed in the mechanism structure, as shown in FIG. Accordingly, depressions 31 for inserting the above-described fixing members are formed on both sides of the light guide plate 30. [

The reflection plate 60 disposed on the lower surface of the light guide plate 30 is also formed with a depressed portion (not shown) corresponding to the depressed portion 31.

2A, depressions 31 of a predetermined depth are formed on both sides of the light guide plate 30 of the conventional backlight unit where the light sources 20 are not located, A fixing member 40 is formed at a position corresponding to the depression 31. Therefore, if the light guide plate 30 is fixed by the fixing member 40, the light guide plate 30 is not moved even if the backlight unit is shaken after assembling. So that the light guide plate 30 and the light source 20 can maintain a constant optimum optical distance d.

However, in such a structure, a part of the light traveling in the light guide plate 30 enters the direction of the depressed portion 31, and the light can not continue to advance due to the shape of the depressed portion 31, The light is concentrated in a certain direction in the vicinity. As a result, a light shining phenomenon occurs in which the screen of some areas becomes brighter than other areas. As the bezel is thinner, a portion where the fixing member 40 is positioned is exposed close to the active area, thereby widening the area in which such light shining phenomenon is visible.

3, in order to maintain the distance between the light source 20 and the light guide plate 30 at the optimum optical distance while solving such light incidence phenomenon, instead of inserting the fixing member 40, A light guide plate guide 50 may be provided.

3 is a view schematically showing a backlight unit using a conventional light guide plate guide 50. Fig. Referring to FIG. 3, the light source 20 of the conventional backlight unit is provided with a light guide plate 50 protruding toward the light guide plate 30 between the point light sources, for example, the light emitting diodes 21. The light guiding plate guide 50 maintains the optimum optical distance d and the light guiding plate 30 is stably supported without the flow even if there is a shake after assembly.

In this case, the light guide plate 50 is positioned between the light emitting diodes 21, so that light emitted from the light emitting diodes 21 located on the right and left sides of the light guide guide 50 is guided to the light guide guide 50, The probability of coupling at the light guide plate 30 in the vertical direction of the light guide plate 30 is lowered, thereby causing dark areas.

The occurrence of such light or dark areas is a major cause of image degradation.

A first object of the present invention is to solve the above-described problem of light and dark parts, and it is a first object of the present invention to maintain a constant gap between a light guide plate and a light source, and at the same time to reduce a bezel.

In order to achieve the above object, a backlight unit and a liquid crystal display device including the same according to the present invention are arranged on a rear surface of a lower cover, a light guide plate, a light source, and a light guide plate so as to be opposed to a light- And a support.

Specifically, the supporting portion is provided with a hole or a groove, and the fixing portion is disposed on one side of the lower cover so as to correspond to the position of the supporting portion. Further, the fixing portion is provided with a protrusion which is fitted in the hole or groove of the supporting portion. That is, the protruding portion of the fixing portion is fitted into the hole or groove of the support portion, so that the light guide plate can be stably fixed.

Alternatively, a protrusion protruding toward the outer side of the lower cover may be provided on the support, and a hole or groove may be provided on one side of the lower cover to engage with the protrusion of the support. Therefore, the projecting portion of the support portion can be fitted into the hole or the groove of the lower cover to stably fix the light guide plate.

According to the backlight unit and the liquid crystal display device including the backlight unit of the present invention, the light guide plate and the light source can maintain the optimum optical distance while solving the light problem and the dark part problem, thereby improving the image quality.

At the same time, since the fixing member is not present, the bezel portion that exists to cover the fixing member can be eliminated, and the reduction of the bezel is possible.

1 is a cross-sectional view of a conventional sidelight type backlight unit.
2A is a plan view of a backlight unit in which a light guide plate is fixed using a conventional fixing member.
2B is a cross-sectional view taken along the line a-a 'in FIG. 2A.
3 is a plan view of a backlight unit in which a light guide plate is fixed using a conventional light guide plate guide.
4 is a plan view of a backlight unit according to the first embodiment of the present invention.
Fig. 5A is an enlarged plan view of Fig. 4A. Fig.
5B is a cross-sectional view taken along line b-b 'of FIG.
6 is a perspective view of a support according to a first embodiment of the present invention.
7 is a perspective view of a fixing part according to the first embodiment of the present invention.
8 is a cross-sectional view according to a second embodiment of the present invention.
9 is a perspective view of a support according to a second embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on the top', 'on the bottom', 'on the back' Or " direct " is not used, one or more other portions may be located between the two portions.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

4 to 7 are diagrams according to a first embodiment of the present invention.

4, the backlight unit according to the present invention includes a lower cover 100, a light source 200 mounted on the lower cover 100, a light guide plate 300, a support 400 attached to the back surface of the light guide plate 300, . ≪ / RTI >

The bottom cover 100 may be accommodated in the backlight unit and may include a bottom surface that is in close contact with the back surface of the backlight unit, and a side where the edge thereof is vertically bent upward.

The light source 200 may include a plurality of light emitting diodes 201 for emitting light and a printed circuit board 202 for mounting a plurality of light emitting diodes 201 spaced apart at a predetermined interval. The printed circuit board 202 may be a flexible printed circuit board and the surface on which the light emitting diode 201 is not mounted, that is, the back surface may be fixed to the side wall of the lower cover 100. Here, the printed circuit board 202 may be fixed to the lower cover 100 by screws or the like or may be fixed using a bonding means such as a double-sided tape or the like.

The plurality of light emitting diodes 201 may be arranged along the light incident surface of the light guide plate 300. The light emitting diode 201 may include a light emitting diode chip that emits red, green, and blue light or emits white light. The light emitting diode 201 may be composed of a plurality of light emitting diode chips emitting red, green, and blue light, respectively. The light emitting diode 201 may emit white light by color mixing by turning on the light emitting diode chips at a time.

The light guide plate 300 is accommodated on the lower cover 100 and can be arranged so that the light entrance surfaces are spaced apart from each other by a predetermined distance so as to maintain an optimum optical distance d with the center of the light emitting diode 201 of the light source 200 have. The light emitted from the light emitting diode 201 is incident on the light incident surface of the light guide plate 300. The light incident from the light guide plate 300 passes through the light guide plate 300 in the direction of the liquid crystal panel (not shown) It can be diverted. The light guide plate 300 may further include a pattern of a specific shape in order to supply a uniform surface light source to a liquid crystal panel (not shown). For example, in order to guide the incident light to the upper surface of the light guide plate 300, various patterns such as elliptical, polygonal, and hologram may be formed on the back surface of the light guide plate 300. Such a pattern may be formed by a printing method or an injection method.

5A to 7, in order to maintain a structure in which the light entrance plane of the light guide plate 300 and the center of the light emitting diode 201 are spaced apart from each other by a predetermined distance, that is, by an optimum optical distance d At least one support part 400 is positioned below each of two opposite side surfaces of the side surface excluding the light incidence surface of the light guide plate 300.

The upper surface 401 of the support part 400 is attached to the back surface of the light guide plate 300 and the hole 402 is provided at the lower part of the support part 400 to prevent the support part 400 from flowing. And is engaged with the protruding portion 501 of the fixing portion 500. However, the hole 402 may be in the form of a groove and is not limited as long as it can engage with the protrusion 501 of the fixing part 500.

Here, the "hole" is a structure in which the upper surface and the lower surface are completely opened, and the "groove" may be a structure in which the upper surface and the lower surface are not completely opened.

Accordingly, the light guide plate 300 can be fixed at a position where the light entrance plane of the light guide plate 300 and the light source 200 are spaced apart by an optimum optical distance d.

The light guide plate 300 and the upper surface 401 of the support part 400 may be attached using an adhesive member. The adhesive member may be a material that is cured by light or heat, and may include at least one of materials having adhesive properties such as acrylic, rubber, and silicone. The adhesive member is applied to the upper surface 401 and cured after a predetermined time elapses or is cured by applying heat at a preset temperature or by irradiating ultraviolet rays.

UV may be used for rapid curing, and a photocurable oligomer resin may be used as the adhesive member. Examples of the photocurable oligomer component include urethane-modified (meth) acrylate, carbonate-introduced urethane-modified (meth) acrylate, and silicone-introduced urethane-modified (meth) acrylate.

The width and length of the hole 402 of the support 400 may be the same as the width of the upper surface 401 of the support 400, And may be shorter than the length. In this case, the upper surface 401 supporting the light guide plate stably supports the light guide plate with a certain width or more, and the portion where the hole 402 is present is reduced in width and length to reduce the weight of the support portion 400 Which can lead to a lighter display.

The support 400 may be made of one or more materials selected from the group consisting of plastic and resin, for example, polycarbonate, polystyrene, and acrylic. Preferably, it may be made of polycarbonate to enable injection molding. Specifically, the support part 400 of the present invention can form the shape of the support part by inserting the support part material into the mold of the support part of the present invention and curing it.

The reflection plate 600 may be disposed on the back surface of the light guide plate 300. The reflection plate 600 can improve the brightness of light by reflecting light passing through the back surface of the light guide plate 300 back to the upper side of the light guide plate 300. The reflection plate 600 may be made of a metal material having high reflectance. Particularly, a side surface of the support part 400 contacting the reflection plate 600 is provided with a groove 403, so that a part of the side surface of the reflection plate 600 can be fitted into the groove 403. Thus, the reflective plate 600 can be positioned as wide as possible among the regions of the back surface of the light guide plate 300 where the support portions 400 are not present.

Since the reflection plate 600 can not be positioned on the back surface of the light guide plate 300 where the support member 400 is located, a reflective member (not shown) capable of providing a reflection effect can be attached to the upper surface 401 of the support member 400 . The reflective member may be a film using high reflectance silver (Ag) or white PET, but is not limited as long as it can give a reflective effect.

The fixing part 500 is provided on the lower cover 100 in correspondence with the position of the supporting part 400. The fixing portion 500 may be formed in an L shape in which the horizontal portion 502 and the vertical portion 503 are present. The upper portion 503 is attached and fixed to the bottom surface and the side surface of the lower cover 100 with an adhesive or the like and is protruded into the side surface of the lower cover 200 in parallel with the horizontal portion 502 in the vertical portion 503. [ The protrusion 501 is fitted into the hole 402 of the support part 400.

The fixing portion 500 may be made of at least one member selected from the group consisting of plastic and resin, for example, polycarbonate, polystyrene, and acrylic. Preferably, it may be made of polycarbonate to enable injection molding. Specifically, the fixing portion 500 of the present invention can form a fixed portion shape by inserting the support material into the mold of the present invention and curing it.

According to the first embodiment of the present invention, it is not necessary to form the depression (31 in Fig. 2A) on the light guide plate itself while maintaining the optimal optical distance between the light guide plate 300 and the light source 200, No light is produced by the light. Further, a reflecting member (not shown) capable of giving a reflection effect is attached to the upper surface 401 of the supporting part 400, so that the dark part is not visible. As described above, according to the first embodiment of the present invention, it is not necessary to cover the portion corresponding to the portion where the support portion 400 is located on the panel, and thus the support portion 400 is located You can also shrink the bezel on the part.

8 to 9 are views according to a second embodiment of the present invention.

8 is a schematic cross-sectional view of a backlight unit according to a second embodiment of the present invention, except that the shape of the supporting part 400 is different and the fixing part 500 does not exist. It is similar to the backlight unit. Therefore, the same reference numerals are assigned to the same components, and only the different components will be described below.

8, in order to maintain a structure in which the light entrance plane of the light guide plate 300 and the center of the light emitting diode 201 are spaced apart from each other by an optimum optical distance, And at least one support portion 400 is located at the lower side of the side surface.

The upper surface 410 of the support part 400 may be attached to the back surface of the light guide plate 300 using an adhesive member. A protrusion 420 protruding in a lateral direction of the lower cover 100 is provided at a lower portion of the support portion 400 to prevent the support portion 400 and the light guide plate 300 having the support portion 400 from moving The lower cover 100 and the lower cover 100 are formed. However, the hole 110 may be in the form of a groove or a shape capable of engaging with the protrusion 420 of the support part 400.

Here, the "hole" is a structure in which the upper surface and the lower surface are completely opened, and the "groove" may be a structure in which the upper surface and the lower surface are not completely opened.

The protrusion 420 of the support part 400 and the hole 110 of the lower cover 100 can be joined using an adhesive member.

8, the protrusion 420 of the supporter 400 is provided with a recess 440 at a portion of the lower cover 100 which abuts the hole 110, The protrusion 420 of the support part 400 may be stably fitted into the hole 110 of the lower cover 100 by providing the convex part 120 at a portion where the concave part 440 contacts the protrusion part 110 have.

The protrusion 420 of the supporting part 400 may have a protrusion at a portion of the lower cover 100 which abuts the hole 110. The protrusion 420 may be formed in the hole 110 of the lower cover 100, The projecting portion 420 of the support portion 400 may be stably fitted into the hole 110 of the lower cover 100. In this case,

The concave portion 440 of the protrusion 420 may be formed in various shapes and may be formed in a shape corresponding to the convex portion 120 of the lower cover 100 to be coupled to the concave portion 440, It is preferable that it is formed in a shape that prevents flow.

The protrusion 420 of the support part 400 may be formed in a single column shape or may have a shape in which a plurality of columns are provided at predetermined intervals, but the present invention is not limited thereto. In this embodiment, a protrusion 420 having two pillars spaced apart from each other at one side of the lower end of the supporting part 400 will be described as an example.

The side surface of the lower cover 100 is positioned between the column and the column so that the area of the hole 110 formed in the side surface of the lower cover 100 is larger than the area of the protrusion 420 Which is smaller than that in the case of a single columnar shape. Accordingly, when the protrusion 420 is provided in the form of two columns, the side surface of the lower cover 100 can more firmly fix the protrusion 420.

In this case, the lower surface of the supporter 400 and the lower cover 100 physically engage with each other using an adhesive member or the like, It is not preferable. When the supporting part 400 and the lower cover 100 are physically fixed, the light guide plate 300, the supporting part 400 and the lower cover 100 are integrated together. In this case, when the light guide plate 300 contracts or expands The separation of the light guide plate 300 and the support portion 400 may occur. 8, the support portion 400 is spaced apart from the lower cover 100 by a predetermined distance so that the light guide plate 300 and the support portion 400 are not separated even if the light guide plate 300 contracts or expands .

If the side surface of the lower cover 100 is very thin, the end of the protrusion 420 of the support part 400 may protrude outside the side surface of the lower cover 100, though not shown. In this case, the tape may be used to cover the lateral side of the lower cover 100 or to cover the side of the case top (not shown).

A groove 430 is provided on a side of the support part 400 contacting the reflection plate 600 so that a part of the side surface of the reflection plate 600 can be fitted into the groove 430. Thus, the reflective plate 600 can be positioned as wide as possible among the regions of the back surface of the light guide plate 300 where the support portions 400 are not present.

Since the reflection plate 600 can not be positioned on the back surface of the light guide plate 300 where the support member 400 is located, a reflection member (not shown) capable of giving a reflection effect to the upper surface 410 of the support member 400 . The reflective member may be a film using high reflectance silver (Ag) or white PET, but is not limited as long as it can give a reflective effect.

According to the second embodiment of the present invention, it is not necessary to form a depression (31 in Fig. 2A) on the light guide plate itself while maintaining the optimal optical distance between the light guide plate 300 and the light source 200, No light is produced by the light. In addition, since the structure (not shown) is attached to the upper surface 401 of the support part 400 to give a reflection effect, the dark part is not visible. As described above, according to the first embodiment of the present invention, it is not necessary to cover the portion corresponding to the portion where the support portion 400 is located on the panel, and thus the support portion 400 is located You can also shrink the bezel on the part.

In addition, since the lower cover 100 is used without requiring a separate fixing part 500, the display device can be made slim and lightweight. Further, since a separate structure other than the support portion 400 is not required, there is an advantage in cost.

Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and various changes and modifications may be made without departing from the scope of the present invention. . Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of protection of the present invention should be construed according to the claims, and all technical ideas within the scope of equivalents should be interpreted as being included in the scope of the present invention.

100: lower cover 200: light source
300: a light guide plate 400:
401: upper surface 402: hole
403: groove 410: upper surface
420: protrusion 430: groove
500: fixing part 501: protrusion
502: horizontal part 503: vertical part
600: reflector

Claims (13)

A lower cover;
A light guide plate housed in the lower cover;
A light source disposed on at least one side of the lower cover and spaced apart from the light incident surface of the light guide plate by a predetermined distance; And
And a support portion disposed on a rear surface of the light guide plate facing the lower cover so as to face the other side of the lower cover on which the light source is not disposed. The method according to claim 1,
Wherein the supporting portion is attached to the back surface of the light guide plate (300) using an adhesive member. The method according to claim 1,
The supporting portion is provided with a first hole or groove,
Further comprising a fixing portion disposed on the other side of the lower cover and having a projection protruding toward the inside of the lower cover to be fitted into the first hole or groove. The method according to claim 1,
The supporting portion is provided with a protruding portion protruding toward the outer side of the lower cover,
And a second hole or groove which is located on the other side of the lower cover and into which the protrusion is fitted. The method according to claim 1,
And a reflective plate positioned below the light guide plate. 6. The method of claim 5,
Wherein the support portion has a third groove on a side contacting with the reflection plate, and the reflector is positioned to fit into the third groove. The method according to claim 1,
Wherein a reflective member having a reflective performance exists on an upper surface of the support portion. 8. The method of claim 7,
Wherein the reflective member is made of Ag or PET. The method of claim 3,
Wherein the light source is located on both sides in the horizontal direction of the lower cover, and the supporting portion is located on one or more sides on both sides in the vertical direction of the light guide plate, and the fixing portion is located at least one side on both sides in the vertical direction of the lower cover. 5. The method of claim 4,
Wherein the second hole or groove has a convex portion, and the support portion has a concave portion at an end of the convex portion, wherein the convex portion and the concave portion are fitted and fixed. 5. The method of claim 4,
Wherein the second hole or groove has a concave portion, and the support portion includes a convex portion at an end of the convex portion, wherein the convex portion and the concave portion are fitted and fixed. 5. The method of claim 4,
Wherein the light source is located on both sides in the horizontal direction of the lower cover, and the support portion is located on at least one of both sides in the vertical direction of the light guide plate, and at least one second hole or groove is provided on the other side of the lower cover. A backlight unit according to any one of claims 1 to 12;
An optical sheet positioned on an upper surface of the light guide plate; And
A liquid crystal panel disposed on an upper surface of the optical sheet,
And the liquid crystal display device.

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