WO2015050238A1

WO2015050238A1 - Liquid crystal display device

Info

Publication number: WO2015050238A1
Application number: PCT/JP2014/076484
Authority: WO
Inventors: 山本　美智雄; 竹志神山; 啓太伊藤; 隆志花尾
Original assignee: シャープ株式会社
Priority date: 2013-10-04
Filing date: 2014-10-03
Publication date: 2015-04-09
Also published as: JP2015092235A

Abstract

Proposed is a technique for minimizing increase of the cost and case strength of a liquid crystal display device having an edge backlight, while maintaining desired heat dissipation characteristics of the backlight and desired display quality. A liquid crystal television (10) is provided with: a display panel (20); a front cabinet (12); a rear cabinet (14); a P chassis (19) for holding the display panel (20); an LED substrate (30) that constitutes an edge LED backlight; a heat sink (40); a backlight chassis (16); and a light guide plate supporting member (50). The heat sink (40) is configured of a substrate arrangement surface (42) that is fitted to the back surface of the LED substrate (30) and a supporting member arrangement surface (44) that is at a predetermined distance from a reflective sheet (25). The light guide plate supporting member (50) is arranged at a predetermined position in the space between the supporting member arrangement surface (44) and the reflective sheet (25).

Description

Liquid crystal display

The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device having an edge type backlight.

In general, LCD TVs and monitors that use edge-type backlights, especially edge-type backlights that use LEDs as the light source, tend to place more emphasis on design in high-value-added models. Progressing. On the other hand, cost reduction design is being promoted in which the luminance is secured by increasing the input power per LED chip and the number of LED chips is reduced. Accordingly, a structure for efficiently radiating the heat generated from the LED backlight is essential.

FIG. 1 shows a cross-sectional structure of a liquid crystal display device 510a according to the background art. Here, the area where the backlight is arranged is shown and focused. A backlight substrate 530 on which an LED chip 532 is mounted is disposed on the edge portion of the display panel 520. Here, the display panel 520 is configured by laminating an LCD panel 521,

optical sheets

522 and 523, an LGP (light guide plate) 524, and a reflection sheet 525 from above. A heat sink 540 (also referred to as a heat spreader or a heat radiating plate) is attached to the back surface of the backlight substrate 530, and the heat sink 540 extends to a lower portion of the reflection sheet 525. A box-type backlight chassis 516 is attached to the outer side surface and the rear side of the heat sink 540. A television power supply board 517 is attached to a predetermined area of the backlight chassis 516.

FIG. 2 shows a cross-sectional structure of another liquid crystal display device 510b according to the background art. In this example, the backlight chassis 516 is changed from a box shape to a flat plate shape. In order to secure the distance between the heat sink 540 and the

optical sheets

522 and 523, the heat sink 540 is disposed outside the backlight chassis 516. The distance from the

optical sheets

522 and 523 can be secured, and the heat dissipation effect of the heat sink 540 itself is improved.

Various technologies have been proposed as such technologies. For example, there is a technique for providing an illuminating device that can improve heat dissipation performance while maintaining structural strength, and that can reduce costs, and an image display device including the illuminating device (see, for example, Patent Document 1). ). Specifically, for the problem of high cost of a T-shaped prismatic frame (extrusion molding, post-screw hole processing), the frame is formed by bending a flat plate (sheet metal processing). By bringing the heat dissipation member and the heat conductive member into contact with each other, a display device capable of improving the heat dissipation performance while maintaining the structural strength and reducing the cost is realized. In addition, there is a technique for realizing a thin and large-screen liquid crystal display device by providing a thin structure that can sufficiently dissipate heat generated by a light source (see, for example, Patent Document 2).

JP 2012-14947 A JP 2010-97924 A

By the way, in the liquid crystal display device 510a of FIG. 1, when the heat radiation from the LED chip 532 is increased, the heat conduction is large, and the display quality is deteriorated by causing thermal deformation (wrinkles) or the like in the region X of the

optical sheets

522 and 523 adjacent to each other. There is a case. Thus, it is a trade-off between the heat dissipation of LED chip 532 and display quality, and another technique has been demanded. In the configuration of FIG. 2, a sufficient distance between the

optical sheets

522 and 523 and the heat sink 540 can be secured. However, since the backlight chassis 516 has a flat plate shape, the strength of the entire casing is reduced, and angle components for reinforcement are required, resulting in problems such as an increase in cost. Was needed.

In order to avoid this, it is ideal to secure a sufficient distance by separating the heat sink from the optical sheet. However, at present, it is difficult to secure a sufficient distance due to the structure under the constraints of thinning and narrowing the frame, and a countermeasure technology is required.

As one of the countermeasures, a heat sink that has been conventionally housed in a box-shaped housing (backlight chassis) is exposed to the outside of the housing to secure a distance from the optical sheet and to enhance the heat dissipation effect of the heat sink itself. A response was proposed. However, in this case, the case cannot be made into a box shape by itself because of the structure, and as a result, there is a problem that the strength of the whole case is lowered as compared with the conventional structure. In order to avoid this decrease in strength, reinforcing parts and the like are required, resulting in an increase in cost, and another technique is required.

In the technique disclosed in Patent Document 1, thermal deformation (wrinkle) is not considered and another technique is required. In the technique described in Patent Document 2, a member having flexibility and elasticity is adopted as the light guide plate support member. As a result, the optical axis of the light incident portion may become unstable, and stable optical characteristics are obtained. Therefore, an additional structure is required, and another technique is required from the viewpoint of cost and the like.

FIG. 3 shows a cross-sectional structure of yet another liquid crystal display device 510c according to the background art. Here, a state in which a predetermined notch of the backlight chassis 516 is formed and there is no support structure by the heat sink 540 is shown. In this case, the reflection sheet 525 may be depressed like a reflection sheet 525a indicated by a broken line in the drawing. In that case, there is a problem that light leakage occurs unless any countermeasure is taken.

The present invention has been made in view of the above situation, and an object thereof is to provide a technique for solving the above problems.

The present invention is attached to a display panel including a light guide member and a reflective sheet disposed on a back surface of the light guide member, an edge type backlight, and a substrate provided with a light source of the edge type backlight. The heat sink has a surface facing the reflective sheet, and a support member made of resin between the facing surface of the heat sink and the reflective sheet. The support member has a trapezoidal cross section, and has a hollow structure in which the bottom side of the trapezoidal side on the heat sink side is open, and the other bottom side abuts the reflective sheet substantially flush.
The support member may include an integrally formed claw-shaped fixing means for fixing to the heat sink.
The heat sink may have a region in contact with the backlight chassis.
Further, the support member may include a reinforcing rib in the region of the hollow structure.
The support member may include a protruding structure that contacts the substrate.

According to the present invention, in a liquid crystal display device having an edge-type backlight, it is possible to propose a technique for minimizing an increase in housing strength and cost while maintaining desired heat dissipation characteristics and display quality of the backlight. it can.

It is a figure which shows the partial cross section structure of the liquid crystal display device based on background art. It is a figure which shows the partial cross section structure of the liquid crystal display device based on background art. It is a figure which shows the partial cross section structure of the liquid crystal display device based on background art. It is a figure which shows the partial cross section structure of the liquid crystal television based on 1st Embodiment. It is a perspective view of the light-guide plate support member based on 1st Embodiment. It is a partial perspective view which shows the light-guide plate support member of the state attached to the backlight chassis based on 1st Embodiment. It is sectional drawing which shows the light-guide plate support member of the state attached to the backlight chassis based on 1st Embodiment. It is a figure which shows the partial cross section structure of the liquid crystal display device based on 1st Embodiment. It is a rear view of the state which exposed the backlight chassis of the liquid crystal television based on 1st Embodiment. It is sectional drawing which shows the light-guide plate support member of the state attached to the backlight chassis based on 2nd Embodiment.

Next, modes for carrying out the present invention (hereinafter simply referred to as “embodiments”) will be specifically described with reference to the drawings.

<First Embodiment>
The outline of the present embodiment is as follows. In other words, an edge-type LED backlight display device structure composed of a light guide plate, an LED substrate, a heat sink for LED heat dissipation, and a BL chassis for fixing the heat sink, supports the light guide plate of the resin molding material in the vicinity of the heat source (LED chip). Parts are provided to ensure a spatial distance between the heat source and the optical sheet.

FIG. 4 shows a partial cross-sectional structure of the liquid crystal television 10 according to this embodiment. Here, a cross-sectional structure of a region where the edge type LED backlight is arranged is shown. As shown in the figure, the liquid crystal television 10 includes a display panel 20, a front cabinet 12, a rear cabinet 14, a P chassis 19 for holding the display panel 20, and an LED substrate 30 constituting an edge type LED backlight. A heat sink 40, a box-type backlight chassis 16, and a light guide plate support member 50.

The display panel 20 has a general configuration, and includes an LCD panel 21,

optical sheets

22 and 23, a light guide plate 24, and a reflection sheet 25 in order from the outside (upper side in the drawing).

A predetermined number of LED chips 32 are linearly arranged on the LED substrate 30 constituting the edge-type LED backlight (see FIG. 6). Here, the LED chip 32 is disposed so as to face the side end portion 24 a (edge portion) of the light guide plate 24. The light emitted from the LED chip 32 enters the inside from the side end 24 a of the light guide plate 24, and the light traveling downward in the figure is reflected by the reflection sheet 25.

A heat sink 40 is attached to the back surface of the LED substrate 30 (the surface on which the LED chip 32 is not disposed). Specifically, the heat sink 40 has an L-shaped cross section as shown in the figure, and is arranged horizontally and displayed in the figure, with a board arrangement surface 42 arranged vertically in the figure and attached to the back surface of the LED board 30. It is comprised from the panel 20 (reflective sheet 25) and the supporting member arrangement | positioning surface 44 spaced apart by predetermined spacing. Here, the board | substrate arrangement | positioning surface 42 is set to the substantially same magnitude | size as the board | substrate surface of the LED board 30, for example, and the supporting member arrangement | positioning surface 44 is set to an area sufficient for heat dissipation.

The light guide plate support member 50 is disposed at a predetermined position in the space between the support member arrangement surface 44 and the reflection sheet 25, specifically, at a position below the outer edge of the display panel 20. The light guide plate support member 50 will be described later with reference to FIG.

The substantially box-shaped backlight chassis 16 is attached to the lower side of the support member arrangement surface 44. Here, the support member arrangement surface 44 is attached to a surface corresponding to the box-shaped bottom surface.

In addition, a part of the P chassis 19 is arranged outside (on the right side in the figure) the board arrangement surface 42 attached to the back surface of the LED board 30, and the box-shaped side face of the backlight chassis 16 is further outside. Is provided. That is, from the back surface of the LED substrate 30, the substrate arrangement surface 42, the partial structure of the P chassis 19 and the side surface portion of the backlight chassis 16 are arranged so as to overlap each other.

FIG. 5 is a perspective view of the light guide plate support member 50. FIG. 6 is a partial perspective view showing the light guide plate support member 50 attached to the backlight chassis 16. 6A shows an end portion of the light guide plate support member 50, FIG. 6B is a cross-sectional view taken along line AA ′ of FIG. 6A, and FIG. 6C is FIG. 6A. FIG. FIG. 7 is a cross-sectional view showing the light guide plate support member 50 attached to the backlight chassis 16. FIG. 7A is a cross-sectional view corresponding to FIG. 6B, and FIG. 7B is a cross-sectional view corresponding to FIG. 6C.

The light guide plate support member 50 is a resin molded product having a substantially rectangular parallelepiped outer shape as shown in FIG. 5, for example, and has a certain strength. Specifically, the light guide plate support member 50 includes a support member base portion 52 that is substantially flush with the reflective sheet 25, and a locking claw 54 and a locking portion 58 that are fixing means to the heat sink 40 (FIG. 7 ( b)). A locking portion 58 is formed on the LED substrate 30 side, and a locking claw 54 is formed on the opposite side.

The length of the support member base portion 52 is a length corresponding to the dimension of the display panel 20, specifically, substantially the same length as the width of the reflection sheet 25. Further, the support member base portion 52 is not a perfect rectangular parallelepiped, has a trapezoidal cross section, and is hollow with a predetermined rib structure inside. With such a structure, the strength of the light guide plate support member 50 is ensured and the amount of heat transfer from the heat sink 40 to the reflection sheet 25 is reduced. More specifically, the support strength with respect to the light guide plate 24 can be improved by making the cross section of the support member base portion 52 into a trapezoidal shape having a “C” shape as illustrated. Moreover, the heat insulation effect can be improved by making the light-guide plate support member 50 into a hollow structure. Furthermore, by adopting a reinforcing rib structure, the support strength for the light guide plate 24 can be sufficiently improved even if the support member base portion 52 has a hollow structure.

As shown in FIG. 5, two locking claws 54 are formed in the vicinity of both ends in the longitudinal direction and one in the center. The locking claw 54 is locked to a locking opening 46 formed on the support member arrangement surface 44 of the heat sink 40. The backlight chassis 16 is formed with a predetermined opening 17a for allowing the backlight chassis 16 to be attached in the locked state. Here, in order to make the latching claw 54 have a predetermined bending characteristic, an opening 56 is formed on the upper surface of the support member base portion 52, and the latching claw 54 extends therefrom, and the support member base portion. It extends to a position exceeding the lower surface of 52. The extending tip has a claw shape facing outward.

The locking portions 58 are formed to extend from the lower surface of the support member base portion 52 by a predetermined number at predetermined positions. The extending tip portion of the locking portion 58 faces outward, and is locked by a locking opening 47 formed on the support member arrangement surface 44. The support member arrangement surface 44 is formed with a predetermined opening 17b that allows the backlight chassis 16 to be attached in the locked state.

When attaching the light guide plate support member 50 to the heat sink 40, the operator fits the locking portion 58 into the locking opening 47 and causes the locking claw 54 to lock into the locking opening 46.

As described above, according to the present embodiment, since the light guide plate support member 50 is a resin molded product having sufficient rigidity, the light guide plate 24 can be stably supported. As a result, the optical axis of the light incident part of the LED chip 32 is stabilized, and the optical characteristics are improved. Moreover, since the light guide plate support member 50 is a resin molded product, the workability of attaching to the backlight chassis 16 is good. For example, when rubber or cushioning material is used, it is necessary to apply it with a double-sided tape or the like. However, in the case of the light guide plate support member 50 which is a resin molded part, hooks such as the locking claws 54 and the locking portions 58 are hooked. It can be handled by the structure and is easy to handle because the part shape is stable. In addition, the cost of parts can be reduced because a double-sided adhesive tape is not required. In addition, when a glass-containing material is used as the material of the light guide plate support member 50, good characteristics can be secured against thermal deformation and thermal expansion.

Compared with the case where the light guide plate support structure is formed in the shape of the heat sink 540 of the conventional liquid crystal television 510a or the like shown in FIG. 1 and the heat capacity of the heat sink 540 itself is increased and dissipated, as in this embodiment. Even if the thickness of the heat sink 40 is reduced and the heat capacity is reduced, the heat dissipation effect can be enhanced.

Furthermore, it is possible to achieve both heat dissipation of the LED chip 32 and reduction of thermal stress on the

optical sheets

22 and 23 and reduce the member cost. For example, as in the cross-sectional structure of the liquid crystal television 10 shown in FIG. 8, by adopting a predetermined diaphragm structure for the backlight chassis 16, both heat dissipation and the fixing structure of the display panel 20 can be achieved well. For example, in the region where the light guide plate support member 50 is disposed, it is necessary to consider the influence of heat to the maximum because the LED substrate 30 is close. Therefore, around the area, the backlight chassis 16 is temporarily expanded in a direction away from the display panel 20. On the other hand, in a region A sufficiently separated from the LED chip 32 (LED substrate 30) that is a heat source, a diaphragm shape is provided so that the backlight chassis 16 is brought into contact with and supported by the display panel 20.

Further, by using the backlight chassis 16 as an aluminum material instead of a conventional iron material, the heat diffusion from the heat sink 40 to the backlight chassis 16 can be improved and the heat capacity can be increased. The front cabinet 12 may be formed of, for example, an aluminum material. Even in such a case, since the resin P chassis 19 is interposed between the heat sink 40 and the front cabinet 12, the front cabinet 12 may be It can prevent that the temperature of the cabinet 12 rises improperly.

Moreover, since the light guide plate support structure by the light guide plate support member 50 which is a resin molded member has low thermal conductivity, heat from a heat source (such as the LED chip 32) is not easily transmitted, and it is attached after the LED unit is attached. The light guide plate support member 50 can be disposed in the immediate vicinity of the LED chip 32. At this time, by providing a protrusion for restraining the LED substrate 30, the LED substrate 30 can also be mechanically fixed, and dedicated screws and rivets for fixing the LED unit can be reduced. As a result, an effect of preventing light leakage due to deformation / dropping of the reflection sheet 25 entering between the light guide plate 24 and the light guide plate support member 50 is also obtained.

Here, the effect of preventing light leakage will be described in detail with reference to FIG. FIG. 9 is a rear view of the liquid crystal television 10 with the backlight chassis 16 exposed. 9A shows the entire backlight chassis 16, FIG. 9B is an enlarged view showing the region C of FIG. 9A with a conventional structure, and FIG. 9C shows FIG. It is the enlarged view which showed the area | region C of a) with the structure of this embodiment. FIG. 9B is substantially the same as the structure described above with reference to FIG.

As shown in FIG. 9B, in the conventional structure, the notch 517c of the backlight chassis 516 does not have the light guide plate support structure of the heat sink 540 due to the relationship of the LED power connector 36. As a result, light leakage due to the drop of the reflection sheet 525 may occur. When light leakage occurs, the optical path is disturbed, causing light emission, leading to deterioration in display quality. However, as shown in FIG. 9C, in this embodiment, the light guide plate support member 50 closes the notch 17 c of the backlight chassis 16, so that light leakage due to the drop of the reflection sheet 25 does not occur.

<Second Embodiment>
FIG. 10 is a cross-sectional view showing the light guide plate support member 50 attached to the backlight chassis 16 according to this embodiment, which is a modification of the structure shown in FIG. 7 of the first embodiment. 10A is a cross-sectional view of a modification corresponding to FIG. 6B, and FIG. 10B is a cross-sectional view of a modification corresponding to FIG. 6C.

There is a concern that the LED substrate 30 in the vicinity of the light guide plate support member 50, which is a resin molded member, cannot be stably fixed to the liquid crystal television 10 due to unexpected vibration or dropping. In particular, the greater the size of the liquid crystal television 10, the greater the concern. Therefore, in the present embodiment, as shown in the drawing, the light guide plate support member 50 has a substrate fixing protrusion forming portion 80. The substrate fixing protrusion forming portion 80 extends from the side surface of the light guide plate support member 50 toward the LED substrate 30. The tip of the substrate fixing protrusion forming portion 80 abuts on the LED substrate 30. In addition, a buffer member may be disposed at a portion that contacts the LED substrate 30.

By providing such a substrate fixing protrusion forming portion 80, mechanical fixing of the LED substrate 30 can be more effectively ensured. That is, it is possible to avoid the displacement and dropping of the LED substrate 30 due to vibration, dropping, or the like. As a result, separate parts such as fixing screws, spacers, and rivets are not necessary for mechanically fixing the LED substrate 30.

The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to combinations of the respective components and the like, and such modifications are within the scope of the present invention. For example, although the LED chip 32 is exemplified as the light source of the backlight, the present invention can also be applied to a backlight using another type of light source (for example, a laser).

In addition, when a member other than the reflection sheet 25 is used as the structure located on the backmost side of the display panel 2, the light guide plate support member 50 may be disposed between the member and the heat sink 40. Further, the present invention is not limited to the liquid crystal television 10 having an edge type LED backlight.
As a backlight of the liquid crystal television 10, for example, there is a structure in which one LED substrate 30 is arranged in the vertical direction or the horizontal direction on the back side of the display panel 20. Further, the light guide plate support member 50 is not limited to a resin molded member, and may be any material having a low thermal conductivity. For example, it may be wood or a composite material member. In the case of a composite material member, it is sufficient that at least a region in contact with the display panel 20 (the reflective sheet 40) has a low thermal conductivity.

DESCRIPTION OF SYMBOLS 10 LCD television 12 Front cabinet 14 Rear cabinet 16

Backlight chassis

17a, 17b Opening 17c Notch part 19 P chassis 20 Display panel 21

LCD panel

22, 23 Optical sheet 24 Light guide plate 25 Reflective sheet 30 LED board 32 LED chip 36 LED power supply connector 40 Heat Sink 42 Substrate Arrangement Surface 44 Support

Member Arrangement Surface

46, 47 Locking Opening 50 Light Guide Plate Support Member (Resin Support Member)
52 support member base 54 locking claw (fixing means)
56 Opening 58 Locking part (fixing means)
80 Protrusion forming part for fixing substrate

Claims

A display panel comprising a light guide member and a reflective sheet disposed on the back surface of the light guide member, an edge type backlight, and a heat sink attached to a substrate provided with a light source of the edge type backlight A liquid crystal display device comprising:
The heat sink has a surface facing the reflective sheet,
Having a resin support member between the opposing surface of the heat sink and the reflective sheet;
The support member has a trapezoidal cross section, and has a hollow structure in which the bottom side of the trapezoid on the heat sink side is open, and the other bottom side abuts the reflective sheet substantially flush with the liquid crystal. Display device.
2. The liquid crystal display device according to claim 1, wherein the support member includes an integrally formed claw-shaped fixing means for fixing to the heat sink.
3. The liquid crystal display device according to claim 1, wherein the heat sink has a region in contact with the backlight chassis.
4. The liquid crystal display device according to claim 1, wherein the support member includes a reinforcing rib in a region of the hollow structure.
The liquid crystal display device according to any one of claims 1 to 4, wherein the support member includes a protrusion structure that contacts the substrate.