KR20070048018A - Back light assembly and liquid crystal display having the same - Google Patents

Abstract

Provided is a backlight assembly in which denaturation of an optical sheet is prevented. The backlight assembly may include at least one optical sheet including a light source, a light guide plate for guiding light emitted from the light source upwardly, and a guide protrusion disposed on the light guide plate and protruding to form a step in at least one corner area. And a mold frame accommodating the optical sheet layer including the optical sheet and having a guide groove accommodating the guide protrusion.

Backlight assembly, optical sheet, fixing projection, liquid crystal display

Description

Back light assembly and liquid crystal display including the same

1 is a schematic exploded perspective view of a backlight assembly according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II 'of FIG. 1.

3 is a plan view of an optical sheet used in a backlight assembly according to an embodiment of the present invention.

4 is a cross-sectional view of a backlight assembly according to another embodiment of the present invention.

5 is a cross-sectional view of a backlight assembly according to another embodiment of the present invention.

6 is a cross-sectional view of a backlight assembly according to another embodiment of the present invention.

7 is a cross-sectional view of a backlight assembly according to another embodiment of the present invention.

8 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

10: light source assembly 20: light guide plate

30: reflective sheet 40: optical sheet

50: lower storage container 60: upper storage container

70: backlight assembly 100: liquid crystal display device

The present invention relates to a backlight assembly and a liquid crystal display including the same. More particularly, the present invention relates to a backlight assembly and a liquid crystal display including the same.

Liquid crystal display is one of the most widely used flat panel displays. It consists of two substrates on which electrodes are formed and a liquid crystal layer interposed between them. The display device is applied to rearrange the liquid crystal molecules of the liquid crystal layer to control the amount of light transmitted. Since the liquid crystal display is a non-light emitting device, it cannot be used where there is no light. In order to compensate for these disadvantages and to enable use even in the dark, a backlight assembly is provided which irradiates uniform light onto the liquid crystal panel.

The backlight assembly includes a light source assembly for generating light and an optical sheet such as a diffusion sheet, a prism sheet, and a protective sheet for increasing the uniformity of the light generated therefrom and collecting the light. Such an optical sheet is mainly fixed by a double-sided adhesive tape or by fixing a hole after extending a portion thereof and then fixing it to a protrusion or the like of the storage container.

However, an optical sheet is mainly expanded by processing a synthetic resin into a sheet shape with a thin thickness, and is expanded by heat. At this time, when the optical sheet is expanded in a state of being firmly fixed by a double-sided adhesive tape or the like, serious display failure occurs such that the expanded optical sheet cannot move and wrinkle occurs in the optical sheet. In order to prevent this, a method of fixing the optical sheet to allow some movement is used. However, when the optical sheet is fixed to be able to move somewhat, the optical sheet may cause friction with other members located adjacent to the optical sheet by vibrations applied from the outside, which may cause serious scratches on the optical sheet.

It is an object of the present invention to provide a backlight assembly in which denaturation of an optical sheet is suppressed.

Another object of the present invention is to provide a liquid crystal display device including the backlight assembly as described above.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided a backlight assembly including a light source, a light guide plate for guiding light emitted from the light source to an upper side, and a top of the light guide plate, and having a step in at least one corner area. And a mold frame including an optical sheet layer including at least one optical sheet having a guide protrusion formed to protrude and receiving the optical sheet, and a guide groove accommodating the guide protrusion.

According to another aspect of the present invention, a liquid crystal display device includes a light source assembly for providing light and an optical characteristic of light provided from the light source assembly, and at least one fixing hole is provided at at least one side thereof. An optical sheet including a formed sheet guide and a fixing protrusion to which at least one fixing hole is coupled are disposed, and a sheet fixing portion having at least one cavity formed adjacent to the sidewall to which the fixing protrusion is attached is formed on the sidewall. A backlight assembly including a storage container, a liquid crystal panel assembly mounted on the backlight assembly and a chassis coupled to the storage container to display an image using light emitted from the backlight assembly, and a chassis to prevent separation of the liquid crystal panel assembly. Include.

Specific details of other embodiments are included in the detailed description and drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hereinafter, a backlight assembly according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a schematic exploded perspective view of a backlight assembly according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II-II 'of FIG. 1. 1 and 2, a backlight assembly 70 according to an embodiment of the present invention may include a light source assembly 10, a light guide plate 20, a reflective sheet 30, an optical sheet 40, and a lower storage container ( 50 and an upper storage container 60.

The light source assembly 10 is disposed on one side or both sides of the light guide plate 20 to provide light to the light guide plate 20. The light source assembly 10 includes a light source 11 and a light source cover 12 surrounding the light source 11.

As the light source 11, a line light source such as a cold cathode light source (CCFL) or a hot cathode light source (HCFL) may be used. The linear light source is supplied with a constant voltage from the outside to emit electrons from the cathode, and irradiates the phosphor to form visible light. One or more such light sources may be disposed in one light source assembly 10.

Another example that can be used as the light source 11 is a point light source such as a light emitting diode (LED). LEDs are semiconductor diodes that emit light when a direct current flows and can convert electrical signals into lights of various colors such as red, green, and blue. When such a point light source is used as the light source 11, a plurality of point light sources may be disposed in one light source assembly 10. In addition, when the point light source is used, the light source cover 12 may be omitted, for example, may be mounted on a flexible printed circuit board of the liquid crystal display.

The light guide plate 20 serves to guide the light emitted from the light source assembly 10 to the upper side of the backlight assembly 70. The light guide plate 20 is made of a material having good refractive index and transmittance, for example, polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene (PE), or the like. A scattering pattern (not shown) for scattering light is formed on the bottom of the light guide plate 20 to guide light incident from the side surface of the light guide plate 20 to the upper side. The scattering pattern may be formed by applying a scattering material to the bottom surface of the light guide plate 20 and patterning the scattering material, and by applying a predetermined bending to the bottom surface of the light guide plate 20, but is not limited thereto.

The reflective sheet 30 is disposed under the light guide plate 20. The reflective sheet 30 serves to increase the brightness of the backlight assembly 70 by reflecting the light emitted through the bottom of the light guide plate 20 to the lower side of the light guide plate 20 back to the upper side of the light guide plate 20. As the reflective sheet 30, a material having good elasticity and excellent light reflection and being used in a thin shape may be used. For example, polyethylene terephthalate (PET) having a thickness of 0.01 mm to 5 mm may be used, but is not limited thereto. In addition, if necessary, a thin film having good elasticity may be used by coating a reflective film to increase light reflection.

The optical sheet 40 is disposed on the light guide plate 20. The optical sheet 40 allows the light guided by the light guide plate 20 to be uniformly radiated to the upper side of the backlight assembly 70. The optical sheet 40 includes a diffusion sheet, a prism sheet, a protective sheet, or the like, and any one of them may be used alone, or a plurality of the sheets may be used in combination. The combination and stacking order of the optical sheet 40 may be variously modified in a range of increasing the uniformity of light. As one example, one diffusion sheet and two prism sheets can be laminated and used.

The optical sheet 40 may be manufactured using a transparent resin such as acrylic resin, polyurethane resin, or silicone resin.

3 is a plan view of an optical sheet used in a backlight assembly according to an embodiment of the present invention. Referring to FIG. 3, the optical sheet 40 includes an optical sheet body 41 and a sheet guide 42. The optical sheet body 41 occupies most of the optical sheet and consists of a substantially rectangular shape. One or more sheet guides 42 are attached to at least one side of the optical sheet body 41. In FIG. 3, two are formed on opposite sides of the optical sheet body 41.

The sheet guide 42 may be connected to the optical sheet body 41 and may be attached using a separate material. The sheet guide 42 may serve to adjust and fix the position of the optical sheet 40, and may distinguish the directionality of the optical sheet 40. That is, as illustrated in FIG. 3, when the sheet guide 42 on the left side is disposed wide and the sheet guide 42 on the right side is disposed narrowly, front and rear of the optical sheet may be easily distinguished.

In addition, a fixing hole 43 for fixing the position of the optical sheet 40 is formed in the sheet guide 42. Fixing protrusions (to be described later) may be coupled to the fixing holes 43 to prevent separation of the optical sheet 40.

Referring again to FIGS. 1 and 2, storage containers 50 and 60 are disposed below the reflective sheet 30 and above the optical sheet 40 to accommodate members constituting the backlight assembly 70. . Here, the storage container located below the reflective sheet 30 will be referred to as the lower storage container 50, and the storage container located above the optical sheet 40 will be referred to as the upper storage container 60.

The lower storage container 50 includes a bottom plate 51 having a rectangular shape and sidewalls 52 that are bent upward to form a storage space from the sides of the bottom plate 51. The above-described light source assembly 10, the light guide plate 20, the reflector 30, the optical sheet 40, and the like are accommodated in the storage space defined by the bottom plate 51 and the side wall 52. The side wall 52 of the lower container 50 is coupled to the upper container 60. The upper accommodating container 60 covers a part of the optical sheet 40 and prevents separation of the optical sheet 40 and the like.

In addition, a sheet fixing part 520 including a fixing protrusion 523 is formed in the side wall 52 of the lower storage container 50 to correspond to the fixing hole 43 of the optical sheet 40. The fixing protrusion 523 of the sheet fixing part 520 penetrates through the fixing hole 43 of the optical sheet 40 to couple the optical sheet 40 to the lower storage container 50.

On the other hand, heat is emitted from the light source assembly 10 located in the storage space in the process of generating light, and other external factors adjacent to the backlight assembly 70 may be combined to increase the temperature inside the storage space. Here, the optical sheet 40 among the members located inside the storage space is relatively thin and reacts sensitively to temperature. That is, expansion and contraction may occur repeatedly in response to changes in temperature. At this time, when the optical sheet 40 is firmly fixed, a wrinkle phenomenon occurs in the optical sheet 40 by repetition of the expansion and contraction. Due to this recession, the quality of the optical sheet may be degraded and the quality of the entire backlight assembly may be deteriorated.

If the optical sheet 40 is not firmly fixed and fluidity is good, when the vibration is applied outside the backlight assembly 70, the optical sheet 40 vibrates and friction with other members occurs. This may cause scratches or the like on the surface of the optical sheet 40 and may deteriorate the quality of the backlight assembly. Therefore, the optical sheet 40 needs to be fixed to have elasticity in the intermediate range of the above conditions.

To this end, a space is left between the inner sidewall 52 of the sheet fixing part 520 to which the fixing protrusion 523 is attached, and the sidewall to which the fixing protrusion 523 is attached. That is, the cavity 522 which the lower part is blocked by the bottom plate 51 is formed.

In addition, the side wall 52 to which the fixing protrusion 523 abuts the cavity 522 is attached has an inclination angle of less than 90 °, and the inclination angle of the side wall 52 to which the cavity 522 and the fixing protrusion 523 is attached is 90 degrees. Will be exceeded. The side wall 52 to which the fixing protrusion 523 is attached is inclined from the cavity 522 in the outward direction of the lower storage container 50. By such a structure, the fixing protrusion 523 may flow to some extent when the optical sheet 40 is expanded or compressed, and at the same time, the fixing protrusion 523 may be buffered while having some resistance to external vibration. Therefore, defects such as scratching or scratching of the optical sheet 40 can be prevented. At this time, preferably, the diameter of the fixing protrusion 523 and the diameter of the fixing hole 43 are the same so that the movement of the fixing protrusion 523 in the fixing hole 43 is prevented.

4 is a cross-sectional view of a backlight assembly according to another embodiment of the present invention. The backlight assembly 71 according to the present exemplary embodiment basically has the same structure as the backlight assembly 70 according to the exemplary embodiment of FIG. 2 and will be mainly described. Referring to FIG. 4, an elastic member 54 such as a spring is attached to the inside of the cavity 522 of the seat fixing part 520 in the horizontal direction. Since the elastic member 54 has a constant modulus of elasticity, it corresponds to an external force but does not flow rapidly. Therefore, when the optical sheet 40 expands or contracts, it may flow somewhat, and even if the side walls 52 of the sheet fixing part 520 are forced inward or outward, the optical sheet 40 buffers it, thereby resisting deformation of the optical sheet 40. Can be promoted and the return to the original state can be promoted. Therefore, deterioration of the optical sheet due to temperature or external vibration can be prevented. In the present embodiment, the cavity 522 has an example of having an angle of about 90 ° with the left and right sidewalls 52, but of course, the cavity 522 may have an acute angle or an obtuse angle, and the same may be applied to the following embodiments. have.

5 is a cross-sectional view of a backlight assembly according to another embodiment of the present invention. The backlight assembly 72 according to the present exemplary embodiment basically has the same structure as the backlight assembly 71 according to the exemplary embodiment of FIG. 4 and will be described based on differences. Referring to FIG. 5, a first elastic member 54a is attached between the fixing protrusion 523 and the side wall contacting the cavity 522. In addition, the fixing protrusion 523 is attached to the side wall 52 using the second elastic member 54b. In this case, the side wall 52 to which the fixing protrusion 523 is attached may have a recessed shape so that the height thereof is relatively lower than the surroundings. From the above structure, the first elastic member 54a and the second elastic member 54b participate in the buffering action, thereby allowing them to flow during expansion or contraction of the optical sheet, and also to cushion against vibration phenomena due to external forces. As a result, defects such as scratches can be prevented.

6 is a cross-sectional view of a backlight assembly according to another embodiment of the present invention. The backlight assembly 73 according to the present exemplary embodiment basically has the same structure as the backlight assembly 71 according to the exemplary embodiment of FIG. 4 and will be described based on differences. Referring to FIG. 6, the cavity 522 is formed in the sheet fixing part 520, and the fixing protrusion 523 is formed on the inner wall 52 based on the cavity 522. Even with such a structure, defects of the optical sheet 40 can be suppressed on the same principle as described above.

7 is a cross-sectional view of a backlight assembly according to another embodiment of the present invention.

Referring to FIG. 7, the backlight assembly 74 according to the present exemplary embodiment is a direct type backlight assembly in which a light source is positioned directly below the optical sheet 40, unlike the exemplary embodiment of FIGS. 2 to 6. In addition, the surface light source 10 'is adopted as a light source, and the light source cover, the light guide plate, and the reflective sheet are omitted.

The surface light source 10 ′ includes a lower substrate 15 and an upper substrate 16. The lower substrate 15 and the upper substrate 16 are bonded to each other to form a chamber including the discharge space 17. Mercury and the like are filled in the discharge space 17, and fluorescent materials are coated on the inner surfaces of the lower and upper substrates 15 and 16. In addition, the reflective layer 13 is disposed on the upper surface of the lower substrate 15.

When a discharge voltage is applied to the surface light source 10 ′ from the outside, mercury or the like present in the discharge space 17 is converted into plasma and emits ultraviolet rays, and the ultraviolet rays are converted into visible light while passing through the fluorescent material. . At this time, the visible light is emitted upward with the help of the reflective layer 13, the output light is high uniformity can be omitted, such as the arrangement of a separate diffuser.

Except for the above structure, it basically has the same structure as the backlight assembly 70 according to the embodiment of FIG. That is, even in the present embodiment, heat may be generated from the surface light source 10 ', and thus, the sheet fixing part of the side wall 52 of the lower storage container 50 to give elasticity to prevent the deterioration of the optical sheet 40. A cavity 522 is formed in 520, and forms an angle with the outer side wall 52.

On the other hand, in the present embodiment, a case where a surface light source is employed as an example of a direct type backlight assembly, the same applies to the case where a linear light source or a point light source is employed, and in this case, a diffuser plate is used to increase the uniformity of the emitted light. It may be further provided.

The backlight assembly according to the exemplary embodiments of the present invention as described above may be applied to a liquid crystal display or the like. Hereinafter, a liquid crystal display according to an exemplary embodiment of the present invention will be described with reference to FIG. 8. 8 is an exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

The liquid crystal display device 100 includes a backlight assembly 70, a liquid crystal panel assembly 80, and a chassis 90.

The liquid crystal panel assembly 80 includes a liquid crystal panel displaying an image, data providing a driving signal for driving the liquid crystal panel, and a gate printed circuit board. The data and gate printed circuit boards are electrically connected to the liquid crystal panel via a Tape Carrier Package (TCP).

The liquid crystal panel includes a first substrate including a thin film transistor and a pixel electrode, a second substrate coupled to the first substrate, and including a common electrode, and a liquid crystal layer interposed between the first and second substrates. Include. On the first substrate, a thin film transistor as a switching element is formed in a matrix form. The data line and the gate line are respectively connected to the source and gate terminals of the thin film transistor, and the pixel electrode made of a transparent conductive material is connected to the drain terminal. Red, green, and blue color filters are alternately formed on the second substrate, and a black matrix pattern is formed between the color filters. A common electrode made of a transparent conductive material is formed on the color filter.

The liquid crystal panel assembly 80 is seated in the backlight assembly 70, and the chassis 90 is coupled with the lower storage container 40 to prevent the liquid crystal panel assembly 80 from being separated from the upper side. The liquid crystal panel assembly 80 To protect.

Meanwhile, in the present embodiment, the backlight assembly 70 according to the embodiment of the present invention is employed, but the backlight assembly 71, 72, 73, 74 according to the other embodiments described above may be employed. to be.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. You will be able to understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

As described above, according to the backlight assembly according to the embodiments of the present invention, since the optical sheets may flow during expansion or contraction, and vibrations due to external vibration application may be prevented, dents and scratches may be prevented. Can be. Therefore, the optical characteristics of the backlight assembly can be maintained. In addition, according to the liquid crystal display device including the backlight assembly as described above, display defects due to modification of the optical sheet may be reduced.

Claims (10)

A light source assembly providing light; An optical sheet deforming an optical characteristic of light provided from the light source assembly, the optical sheet including a sheet guide having at least one fixing hole formed on at least one side thereof; And And a receiving container having a fixing protrusion to which at least one fixing hole is coupled, and a sheet fixing portion having at least one cavity formed adjacent to the side wall to which the fixing protrusion is attached. According to claim 1, And a side wall to which the fixing protrusion is attached is located outside the storage container from the cavity. According to claim 1, And a side wall to which the fixing protrusion is attached is inclined outwardly from the cavity from the cavity. According to claim 1, And an elastic member attached within said cavity to laterally connect said cavity. According to claim 1, The fixing protrusion is attached to the side wall and the elastic member using. An optical sheet including a light source assembly for providing light, a sheet guide that modifies the optical characteristics of the light provided from the light source assembly, and at least one fixing hole formed on at least one side thereof, and a fixing protrusion to which the at least one fixing hole is coupled A backlight assembly including an accommodating container having a sheet fixing part disposed on the side wall, wherein the sheet fixing part is formed adjacent to the side wall to which the fixing protrusion is attached; A liquid crystal panel assembly configured to display an image by using light emitted from the backlight assembly and to be seated on the backlight assembly; And And a chassis coupled to the storage container to prevent separation of the liquid crystal panel assembly. The method of claim 6, And sidewalls having the fixing protrusions positioned outside the storage container from the cavity. The method of claim 6, And sidewalls having the fixing protrusions inclined from the cavity in an outward direction of the storage container. The method of claim 6, And an elastic member attached to the cavity to connect the cavity in the lateral direction. The method of claim 6, And the fixing protrusion is attached to the sidewall and the elastic member.

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