KR101011585B1 - Backlight device - Google Patents

Abstract

The present invention relates to a backlight device having a light guide plate holder provided between a plurality of light guide plates to implement a large screen to prevent productivity of the light guide plate even under thermal expansion or external impact, thereby improving productivity and image quality. A plurality of light guides are arranged in the horizontal and vertical directions so that the light guide portion of the light guide plate overlaps the light receiving part seating surface of a neighboring light guide plate, and a plurality of light sources are disposed on the light incident portion side of each light guide plate, and a reflecting plate is disposed below each light guide plate. The backlight device having a structure in which a diffuser plate and an optical sheet are stacked on the light guide plate, wherein at least one hole is formed in a seating surface of the light guide plate, and a light guide plate holder having an emboss projecting downward from a position corresponding to the hole is formed. Is pressed with the cover bottom while pressing the seating surface of the light guide plate, And to prevent the light guide plate from flowing.

LCD, backlight, LGP, LGP holder, diffusion sheet

Description

Backlight unit

The present invention relates to a backlight device, and more particularly, a light guide plate holder is provided between a plurality of light guide plates arranged to implement a large screen, thereby improving productivity and image quality by preventing the light guide plate from flowing under thermal expansion or external impact. It relates to a backlight device.

In general, a liquid crystal display (LCD) is widely used as a flat panel display because it can be driven using low power and has a vivid color reproduction ability. However, unlike CRTs and PDPs, LCDs are non-light-emitting devices that do not emit light directly, and require a separate backlight unit using fluorescent lamps to irradiate light from the back of the LCD panel to the panel. do.

Back light used in the liquid crystal display is classified into a front dimming type (or direct type) and a side dimming type (or edge type) according to a method of disposing a light source. Direct-lighting is to place the light source on the lower side of the flat plate. Since the shape of the light source is shown on the liquid crystal panel, the space between the light source and the liquid crystal should be secured and maintained. Since the light scattering means must be installed separately, there is a limit to thinning. Edge-lighting is a method of distributing light to the entire surface by using a light guide panel after installing a light source on the outside of a flat plate, which has a problem of low luminance and highly optical processing technology for the light guide plate. Is required.

At this time, the light source of the back light device may be a fluorescent lamp such as CCFL (Cot Cathode Fluorescent Lamp), HCFL (Hot Cathode Fluorescent Lamp), EEFL (External Electrode Fluorescent Lamp), LED (Light Emitting Diode) device, EL (Electro) Luminescence element is mainly used.

As shown in FIG. 1, the general structure of the side-illuminated backlight device forms a structure in which a plurality of LEDs 3 arrays are disposed on one side of the light guide plate 2, and the light is collected and distributed on the upper side of the light guide plate 2. The optical sheets 4 and 5 are stacked so that the light of the point light source emitted from the LED 3 is converted into the surface light source while passing through the light guide plate 2 and is emitted to the upper side of the light guide plate.

On the other hand, in recent years, as a display device such as an LCD becomes larger and larger, a backlight device is also required. In the backlight device for implementing the large screen, as illustrated, a plurality of light guide plates 2 are arranged in the horizontal and vertical directions inside the cover bottom 1, and an array of LEDs 3 is disposed at one side of each light guide plate 2. On the upper side of the light guide plate 2, a diffuser plate 4 and an optical sheet 5 for condensing and dispersing light are stacked.

However, the backlight device as described above may implement a large screen by a plurality of light guide plates, but each light guide plate 2 is not stably fixed, so that a flow occurs in a vertical direction or a horizontal direction, and adjacent to each other by heat generated during backlight operation. There exists a possibility that the space | interval between light guide plates may change. The flow of the light guide plate does not provide stable image quality as a backlight device.

In addition, a reflecting plate (see 80 in FIG. 5) is disposed below the light guide plate 2 to reflect light emitted downward to the upper side. The reflecting plate 80 is provided on the light guide side by the wedge-shaped light guide plate 2 structure. There is a problem that sag downwards.

In addition, the light guide plate 2 and the diffusion plate 4 stacked on the upper side are in contact with each other due to thermal expansion, friction, or the like, which causes a problem of degrading the image quality of the backlight device.

The backlight device using a plurality of light guide plates according to the prior art has a problem in ensuring reliability as a backlight device because the gap between the light guide plates is not kept constant.

The present invention has been proposed to solve the above problems, and in the backlight device in which a plurality of light guide plates are arranged in the horizontal and vertical directions, a light guide plate holder for preventing the movement of the light guide plate between adjacent light guide plates is provided, which is stable. An object of the present invention is to provide a backlight device that guarantees image quality.

In addition, an object of the present invention is to provide a backlight device in which the support is formed in the light guide plate holder to prevent sagging of the reflector to provide stable brightness.

In addition, an object of the present invention is to provide a backlight device between the light guide plate and the diffusion plate is provided with a diffusion sheet for preventing friction between the light guide plate and the diffusion plate, to improve the quality of the screen.

The backlight device of the present invention for achieving the above object is arranged in a plurality in the horizontal and vertical direction so that the light guide portion of the light guide plate overlaps the mounting surface formed in the light incident portion of the neighboring light guide plate inside the cover bottom, A plurality of light sources are disposed on the light incident part side, a reflecting plate is disposed below each light guide plate, and a diffuser plate and an optical sheet are stacked on the light guide plate to prevent the light guide plate from flowing. The light guide plate holder is configured to be engaged with the cover bottom while pressing the mounting surface of the light guide plate.

In the above-described configuration, at least one hole is formed in the seating surface of the light guide plate, and the light guide plate holder is formed with an emboss protruding downward from a position corresponding to the hole, and the emboss is inserted into and fastened to the hole. It is characterized in that it is configured to prevent the flow in the horizontal direction.

In the above-described configuration, the hole of the light guide plate is a hole having a length in the x direction to prevent the flow in the y direction and ensure the degree of freedom for thermal expansion in the x direction, and a length in the y direction to prevent the flow in the x direction (X direction refers to the direction of the light incident portion of the light guide plate, that is, the direction in which the light sources are arranged, and the y direction is the direction from the light incident portion through which light travels in the vertical direction toward the light facing portion). Says.)

In the above configuration, the light guide plate holder is characterized in that the support portion protruding upward to prevent the reflecting plate of the neighboring light guide plate from sagging.

In the above-described configuration, a flexible diffusion sheet for preventing friction between the light guide plate and the diffusion plate is further provided between the light guide plate and the diffusion plate.

According to the present invention having the above configuration, each adjacent light guide plate can be stably fixed, thereby ensuring excellent image quality even when thermal expansion or external impact is applied.

In addition, the reflective plate may be prevented from sagging between the light guide plate and the cover bottom, thereby providing stable luminance.

In addition, the quality of the screen can be improved by preventing the friction between the light guide plate and the diffusion plate by the diffusion sheet.

The technical problems achieved by the present invention and the practice of the present invention will be more clearly understood by the preferred embodiments of the present invention described below. The following examples are merely illustrative of the present invention and are not intended to limit the scope of the present invention. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a perspective view illustrating a backlight device using a plurality of light guide plates according to an exemplary embodiment of the present invention.

Referring to the drawings, in the backlight device according to the embodiment of the present invention, a plurality of light guide plates 20 are arranged in a horizontal and vertical direction to implement a large screen inside the cover bottom 10, and at one side of the light guide plate 20. A plurality of LEDs 30, which are light sources, are disposed, and the diffusion sheet 60, the diffusion plate 40, and the optical sheet 50 are sequentially stacked on the light guide plate 20. In addition, a reflecting plate (80 of FIG. 5) is provided below the light guide plate 20, and a light guide plate holder (70 of FIG. 3) is provided on the light incident part and the light guide part of the neighboring light guide plate 20. Here, the cover bottom 10, the LED 30, the diffusion plate 40, the optical sheet 50, and the reflecting plate 80 are general known configurations of the backlight device, and thus detailed description thereof will be omitted.

The light guide plate 20 is configured to convert the light of the point light source incident from the LED 30 to the surface light source by total internal reflection and to emit the light upwardly. Are arranged as dogs. On one side of each light guide plate 20, a plurality of LEDs 30, which are light sources, are disposed along the light receiving part, and the light receiving parts of one light guide plate 20-1 and the light guide parts of the adjacent light guide plate 20-2 overlap each other. In consideration of the amount of light incident from the LED 30, the light incident part is generally thick, and the light incident part has a thin wedge shape (where the light incident part is the side where light is incident on the LED, and the light receiving part is vice versa). Says the side).

 The diffusion sheet 60 is configured to prevent friction due to contact between the light guide plate 20 and the diffusion plate 40 between the light guide plate 20 and the diffusion plate 40, and has a flexible light having excellent light transmittance. It is prepared in the form of a thin film using a resin of). In general, the light guide plate 20 and the diffuser plate 40 are stacked at a minimum interval to slim the backlight device, and the light guide plate 20 and the diffuser plate 40 have a thick panel form using hard resin material. Is manufactured. In this case, scratches may occur on the upper surface of the light guide plate 20 and the lower surface of the diffusion plate 40 due to thermal expansion or contact by external impact. Such scratches degrade the quality of image quality such as brightness and uniformity of brightness in the backlight device. Therefore, the diffusion sheet 60 made of a soft resin material is inserted between the light guide plate 20 and the diffusion plate 40 to block direct contact between the light guide plate 20 and the diffusion plate 40, thereby preventing scratches caused by friction. To ensure stable image quality.

In addition, a reflecting plate 80 is disposed on the lower surface of the light guide plate 20 to re-reflect light emitted from the lower side of the light guide plate to the upper side, and the light guide plate holder 70 is disposed at a portion where the light incident portion and the light receiving portion side of the neighboring light guide plate overlap. ), Which will be described in detail below.

3 is a perspective view illustrating a structure in which a plurality of light guide plates are arranged in a backlight device according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view AA of the light guide plate and the light guide plate holder according to the exemplary embodiment of FIG. 3. 3 is a sectional view taken along line BB of the light guide plate and the light guide plate holder according to the embodiment of FIG. 3.

Referring to FIG. 3, in the backlight device according to the exemplary embodiment of the present invention, a plurality of light guide plates 20 are arranged so that a part of the light guide part and the light guide part overlap each other, and the light guide plate 20 flows between neighboring light guide plates 20. The light guide plate holder 70 is provided to prevent the same.

In detail, each of the wedge-shaped light guide plates 20 is formed such that a seating surface 22 for mounting the light guide portion of the light guide plate 20 adjacent to the light incident portion forms a step, and is formed on the seating surface 22. The light guide portions of neighboring light guide plates are seated and overlapped with each other.

Meanwhile, the light guide plate holder 70 is disposed between the seating surface 22 of the light guide plate 20 and the light guide portion of the adjacent light guide plate 20. That is, when assembling the backlight device, the light guide plate 20 is disposed first, and then a part of the light guide plate holder 70 is disposed to overlap the seating surface 22, and another light guide plate 20 is disposed adjacent to the side surface. .

In this case, the light guide plate holder 70 is fixed to the cover bottom 10 by screws or rivets 11, and a part of the light guide plate holder 70 presses the seating surface 22 of the light guide plate 20. This prevents it from flowing in the vertical direction.

A plurality of holes 21 are formed in the seating surface 22 of the light guide plate, and an emboss 71 protruding downward from the position corresponding to the hole 21 is formed in the light guide plate holder 70.

That is, as shown in FIG. 4, the light guide plate holder 70 fixed to the cover bottom 10 has the cover bottom 10 in a state in which the emboss 71 is inserted into and fastened to the hole 21 of the light guide plate 20. Since it is fixed to, to prevent the flow of the light guide plate 20 in the horizontal direction (x and y direction). The holes 21 may be formed in different shapes, and the holes 21a having the length in the x direction and the holes 21b having the length in the y direction are formed by repeating each other (where the x direction is the mouth of the light guide plate). Refers to the direction of the light portion, that is, the direction in which the light sources are arranged, and the y direction refers to the direction from the light incident portion through which light, which is the vertical direction, to the light facing portion).

The hole 21a having a length in the x direction serves as a crystal ball to prevent the light guide plate from flowing in the y direction and at the same time ensures the degree of freedom of thermal expansion in the x direction of the light guide plate by heat generated during the backlight operation. In order to guarantee the degree of freedom for thermal expansion, the hole 21 of the light guide plate and the emboss 71 of the light guide plate holder have a gap c of the hole 21, a diameter a of the emboss 71, and a diameter of the long axis hole 21 a. As shown in Figure 4 between (b),

There is a correlation of c ≧ (b−a) / 2 ≧ Δt * α * c.

(Where α is the coefficient of linear expansion of the light guide plate, and Δt is the minimum value of the temperature change.)

In addition, the hole 21b having a length in the y direction serves as a crystal ball for preventing the light guide plate from flowing in the x direction.

Accordingly, as described above, holes having lengths in the x direction and the y direction are repeatedly formed, and the emboss 71 of the light guide plate holder 70 is inserted into the holes so that the light guide plate 20 is in the x direction and the y direction in the horizontal direction. Can be prevented from flowing.

On the other hand, referring to Figure 5, the light guide plate holder 70 according to an embodiment of the present invention is formed with a support portion 72 for supporting the reflecting plate.

As shown in the drawing, the reflector 80 provided under the light guide plate 20 having a thin wedge shape forms a thin film. The gap between the light guide plate 20 and the cover bottom 10 gradually increases toward the light guide part. Since it loses, the reflecting plate 80 may sag downward due to the load. Therefore, the support portion 72 protrudes upward in parallel with the inclined surface of the reflector 80 along the surface of the light guide plate holder 70, thereby supporting the reflector 80 and preventing sagging downward.

In the backlight device according to the embodiment of the present invention having the above structure, the light guide plate 20 is prevented from flowing in the vertical direction of the upper and lower sides by pressing the light guide plate holder 70, and the hole of the light guide plate 20 and the light guide plate holder ( Flowing in the horizontal direction by the emboss 71 of 70 is prevented, and sagging of the reflecting plate 80 by the support portion 72 of the light guide plate holder 70 is prevented.

Although the embodiments of the present invention have been described with reference to the present invention, those skilled in the art will understand that various modifications and equivalent other embodiments are possible therefrom.

1 is a perspective view showing a backlight device using a plurality of light guide plates according to the prior art;

2 is a perspective view illustrating a backlight device using a plurality of light guide plates according to an embodiment of the present invention;

3 is a perspective view illustrating a structure in which a plurality of light guide plates are arranged in a backlight device according to an embodiment of the present invention;

Figure 4 is a cross-sectional view A-A showing the structure of a light guide plate and a light guide plate holder according to an embodiment of the present invention,

Figure 5 is a cross-sectional view B-B showing the structure of a light guide plate and a light guide plate holder according to an embodiment of the present invention.

** Description of symbols for the main parts of the drawing **

10: cover bottom 11: screw (or rivet)

20: light guide plate 21: hole

22: seating surface 30: LED

40 diffuser 50 optical sheet

60: diffusion sheet 70: light guide plate holder

71: emboss 72: support

80: reflector

Claims (4)

A plurality of light sources are arranged in the cover bottom in the horizontal and vertical directions so that the light guide portion of the light guide plate overlaps the light receiving part seating surface of a neighboring light guide plate, and a plurality of light sources are disposed on the light incident portion side of each light guide plate, and a reflector plate is disposed below each light guide plate. In the backlight device having a structure in which a diffuser plate and an optical sheet are stacked above the light guide plate, At least one hole is formed in the seating surface of the light guide plate, A light guide plate holder having an emboss projecting downward from a position corresponding to the hole is fastened to the cover bottom while pressing the seating surface of the light guide plate, The backlight device is configured to prevent the flow of the light guide plate. The method of claim 1, The hole of the light guide plate is a hole having a length in the x direction to prevent the flow in the y direction and ensure the degree of freedom for thermal expansion in the x direction, and a hole having a length in the y direction to prevent the flow in the x direction is repeated A backlight device, characterized in that formed. (The x direction refers to the direction of the light incidence part of the light guide plate, that is, the direction in which the light sources are arranged, and the y direction refers to the direction from the light incidence part through which light, which is its vertical direction, to the light part.) The method according to claim 1 or 2, The light guide plate holder is a backlight device, characterized in that the support portion protruding upward to prevent the reflecting plate of the neighboring light guide plate is formed. The method according to claim 1 or 2, And a flexible diffusion sheet further provided between the light guide plate and the diffusion plate to prevent friction between the light guide plate and the diffusion plate.

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