WO2014131225A1

WO2014131225A1 - Backlight module and display device

Info

Publication number: WO2014131225A1
Application number: PCT/CN2013/073902
Authority: WO
Inventors: 吕昶; 占江徽
Original assignee: 合肥京东方光电科技有限公司; 京东方科技集团股份有限公司
Priority date: 2013-02-26
Filing date: 2013-04-08
Publication date: 2014-09-04
Also published as: CN103148414A

Abstract

A backlight module and a display device, which are used for solving the problem of non-uniform brightness of backlight modules. The backlight module comprises a light guide panel (20), and at least one CCFL (40) arranged on at least one side surface of the light guide panel (20), wherein the distance from both ends of the CCFL (40) to at least one side surface of the light guide panel (20) is less than that from the middle location of the CCFL (40) to at least one side surface of the light guide panel (20).

Description

Backlight module and display device

Embodiments of the present invention relate to a backlight module and a display device. Background technique

The backlight module provides a light source for a liquid crystal display (LCD) and is an important component of the LCD. In the prior art, in view of the advantages of mature process and stable performance of the Cold Cathode Fluorescent Lamp (CCFL), CCFL is generally used as a light-emitting device in a backlight module. In order to reduce the thickness of the LCD, it is currently preferred to arrange the illuminating device on the side of the backlight module.

As shown in FIG. 1 , it is a schematic structural diagram of a conventional CCFL side-entry backlight module. The backlight module comprises: a bottom reflective sheet 10, a light guide plate 20 disposed on the bottom reflective sheet, an optical film 30 disposed above the light guide plate, and a CCFL 40 disposed on at least one side of the light guide plate. Moreover, in order to improve the luminous efficiency of the CCFL 40, the lamp cover 50 is disposed around the CCFL 40 so that all of the light emitted from the CCFL 40 is incident inside the light guide plate 20.

In the structure of the existing CCFL side-lit backlight module, the CCFL 40 is designed as a straight tube, and the thickness of the light guide plate 20 along the length of the CCFL is the same. However, due to the difference in luminous efficiency between the CCFL intermediate position and the two ends, Therefore, when the light guide plate adopts the same thickness, the brightness of the middle portion and the two ends of the light exit surface of the light guide plate are different, resulting in a phenomenon in which the backlight module has poor uniformity of brightness. Summary of the invention

Embodiments of the present invention provide a backlight module and a display device, which can be used to overcome the problem of uneven brightness of the backlight module.

An aspect of the present invention provides a backlight module, including: a light guide plate, at least one CCFL disposed on at least one side of the light guide plate; wherein, the two ends of the CCFL are at least one side of the light guide plate The distance is less than a distance from an intermediate position of the CCFL to at least one side of the light guide plate.

For example, the shape of the CCFL may be curved. Further, for example, the distance between the two ends of the CCFL to at least one side of the light guide plate may be equal.

For example, at least one side of the light guide plate is along a length direction of the CCFL, and a thickness of the light guide plate may be increased from an intermediate position to both ends.

For example, the backlight module may further include: a lamp cover surrounding the CCFL.

Further, for example, the lamp cover may be U-shaped.

For example, the face of the lamp cover adjacent to the CCFL may be provided with a reflective layer or the lamp cover may be a reflective lamp cover.

For example, the backlight module may further include: a bottom reflective sheet disposed under the light guide plate. For example, the backlight module may further include: an optical film disposed above the light guide plate. Another aspect of the present invention provides a display device comprising: any one of the above backlight modules. DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly described below. It is obvious that the drawings in the following description relate only to some embodiments of the present invention, rather than to the present invention. limit.

1 is a schematic structural view of a conventional backlight module;

2 is a schematic structural view of a conventional CCFL;

3 is a schematic diagram of a relationship between a brightness and a length of a CCFL according to an embodiment of the present invention; FIG. 4 is a schematic diagram showing a relationship between a distance from a CCFL to a light guide plate and a brightness of a CCFL according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a backlight module according to Embodiment 1 of the present invention; FIG.

FIG. 6 is a schematic structural diagram of a backlight module according to Embodiment 2 of the present invention; FIG.

7 is a schematic diagram of calculating a CCFL arc according to a second embodiment of the present invention; FIG. 8 is a schematic diagram showing a relationship between a thickness of a light guide plate and a light efficiency of light entering according to an embodiment of the present invention;

FIG. 9 is a schematic structural diagram of a backlight module according to Embodiment 3 of the present invention.

Reference mark:

10- bottom reflector; 20-light guide; 30-optical diaphragm; 40-CCFL; 50-shade. detailed description

The technical solutions of the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings of the embodiments of the present invention. It is apparent that the described embodiments are part of the embodiments of the invention, rather than all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the described embodiments of the present invention without departing from the scope of the invention are within the scope of the invention.

The drawings are for illustrative purposes only and are not intended to be Unless otherwise defined, technical terms or scientific terms used herein shall be of the ordinary meaning understood by those of ordinary skill in the art to which the invention pertains. The words "first", "second" and similar terms used in the specification and claims of the present invention do not denote any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the words "a", "an", "the" and the like do not denote a quantity limitation, but mean that there is at least one. The words "including" or "comprising", etc., are intended to mean that the elements or objects preceding "including" or "comprising" are intended to encompass the elements or Component or object. Words such as "connected" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Upper", "Down", "Left", "Right", etc. are only used to indicate the relative positional relationship. When the absolute position of the object to be described is changed, the relative positional relationship may also change accordingly.

The embodiment of the present invention provides a backlight module, including a light guide plate 20, and a CCFL 40 disposed on at least one side of the light guide plate, and a distance between two ends of the CCFL 40 to at least one side of the light guide plate 20 is smaller than The distance from the intermediate position of the CCFL 40 to at least one side of the light guide plate 20 is described.

It should be noted that, in all embodiments of the present invention, both ends of the CCFL 40 refer to two end points of the effective light-emitting area along the length direction of the entire CCFL; correspondingly, the CCFL The intermediate position of 40 means the middle of the entire CCFL along its length, which is usually the middle of the effective light-emitting area.

For example, as shown in FIG. 2 , taking the backlight module in the current 18.5-inch display product as an example, the CCFL 40 is elongated, including an effective light-emitting area, and a non-light-emitting area on both sides of the effective light-emitting area. The non-light-emitting area includes electrodes, mounting portions, etc., and generally the non-light-emitting areas on both sides are the same; the length of the non-light-emitting area is, for example, 1.5 ± 0.2 mm, and accordingly the length of the entire CCFL 40 is, for example, 421 ± 1 mm. If the length of the non-light-emitting area at both ends is 1.5 mm, the length of the entire CCFL 40 is 421 mm. Then, both ends of the CCFL 40 referred to in the embodiment of the present invention, that is, in the length direction, 1.5 mm from the left end (or the right end), and 419.5 mm.

Second, the distance from the two ends of the CCFL 40 to the light guide plate 20 refers to the vertical distance from the two ends of the CCFL 40 to the side of the light guide plate 20 that is closest to the CCFL 40. The distance from the intermediate position of the CCFL 40 to at least one side of the light guide plate 20 refers to the vertical distance from the intermediate position of the CCFL 40 to the side of the light guide plate 20 closest to the CCFL 40. .

Since the LCD is usually rectangular, the shape of the light guide plate is the same as that of the LCD, and is usually rectangular. The side of the light guide plate on which the CCFL is disposed is usually the long side or the short side of the rectangle.

The distance from the two ends of the CCFL 40 to the light guide plate 20 and the distance from the intermediate position of the CCFL 40 to the light guide plate 20 are set according to actual conditions, which is not limited herein.

The design principles of the present invention are described below. Figure 3 is a graphical representation of the relationship between brightness and length of CCFL 40. As can be seen from Fig. 3, the luminance at the intermediate position of the CCFL 40 is larger than the luminance at both ends.

Taking a backlight module in a display product of 18.5 inches as an example, referring to FIG. 3, the CCFL

The brightness of the intermediate position of 40 is about 68000 cd/m ² , and the brightness becomes smaller and smaller at the position closer to both ends.

4 is a graph showing the relationship between the distance from the CCFL 40 to the light guide plate 20 and the brightness of the CCFL 40. As can be seen from Fig. 4, as the distance from the CCFL 40 to the light guide plate 20 is further, the brightness of the CCFL 40 is gradually lowered.

Taking the backlight module in the display product with a screen of 18.5 inches as an example, referring to FIG. 4, when the distance from the CCFL 40 to the light guide plate 20 is about 1.2 mm, the brightness of the CCFL 40 is the highest at this time. Bright, about 66000 cd/m ² , and when the distance from the CCFL 40 to the light guide plate 20 is greater than 1.2 mm, the brightness becomes smaller as the difference becomes larger.

According to the above analysis, in order to improve the uniformity of the brightness of the backlight module, the

The distance from the both ends of the CCFL 40 to the light guide plate 20 is such that the luminous fluxes of the both ends and the intermediate portion of the CCFL 40 entering the light guide plate 20 are the same.

The embodiment of the present invention provides a backlight module. The backlight module includes a light guide plate 20, a CCFL 40 disposed on at least one side of the light guide plate, and a distance from the two ends of the CCFL 40 to the light guide plate 20. Less than the distance from the intermediate position of the CCFL 40 to the light guide plate 20; The distance between the two ends of the CCFL 40 and the light guide plate 20 is shortened, thereby improving the brightness of the two ends of the backlight module, thereby improving the uniformity of the brightness of the backlight module.

Optionally, the backlight module further includes: a bottom reflective sheet 10 disposed under the light guide plate. The bottom reflective sheet 10 may be provided separately, for example, or may be realized by a reflective layer on the back panel of the backlight module.

Optionally, the backlight module further includes: an optical film 30 disposed above the light guide plate. The optical film 30 may be a single film layer or a plurality of film layers including, for example, an antireflection film, a diffusion film, and the like.

The first embodiment provides a backlight module, as shown in FIG. 5. The backlight module includes: a bottom reflective sheet 10, a light guide plate 20 disposed on the bottom reflective sheet, and an optical film disposed above the light guide plate. The sheet 30 is disposed on the CCFL 40 on at least one side of the light guide plate; the distance from the two ends of the CCFL 40 to the light guide plate 20 is smaller than the distance from the intermediate position of the CCFL 40 to the light guide plate 20.

It can be seen from the relationship between the distance from the CCFL 40 of FIG. 4 to the light guide plate 20 and the brightness of the CCFL 40 that when the distance between the two ends of the CCFL 40 to the light guide plate 20 is smaller than the When the intermediate position of the CCFL 40 is at a distance from the light guide plate 20, the brightness of both ends of the CCFL 40 is compared with the distance from the two ends of the CCFL 40 to the light guide plate 20 in the prior art and the CCFL 40. When the intermediate position is equal to the distance of the light guide plate 20, the brightness thereof becomes bright.

It should be noted that, in the first embodiment of the present invention, the shape of the CCFL 40 is not limited, and only the distance from the two ends of the CCFL 40 to the light guide plate 20 is smaller than the middle of the CCFL 40. The distance to the light guide plate 20 is sufficient.

Preferably, for example, the CCFL 40 may have an arc shape, such as an arc or an arc that intercepts other curved portions.

Further, for example, the distance between the two ends of the CCFL 40 to the light guide plate 20 is equal. The second embodiment provides a backlight module that can be applied to a 18.5 inch display product. Referring to FIG. 5 , the backlight module includes a bottom reflective sheet 10 , a light guide plate 20 disposed on the bottom reflective sheet, and an optical film 30 disposed on the light guide plate disposed on at least one side of the light guide plate. CCFL 40.

The shape of the CCFL 40 is curved, and the distance from the two ends of the CCFL 40 to the light guide plate 20 is smaller than the distance from the intermediate position of the CCFL 40 to the light guide plate 20. As shown in Figure 6, The distance from the two ends of the CCFL 40 to the light guide plate 20 may be 1.2 mm, and the distance from the center of the CCFL 40 to the light guide plate 20 may be 1.7 mm (Fig.

Not marked in).

It can be seen from the relationship between the distance from the CCFL 40 of FIG. 4 to the light guide plate 20 and the brightness of the CCFL 40 that the distance from the two ends of the CCFL 40 to the light guide plate 20 is 1.2 mm. At the same time, the brightness of the CCFL 40 is the brightest, so that the brightness of both ends of the CCFL 40 can be brightened.

In addition, in the embodiment of the present invention, when the distance from the two ends of the CCFL 40 to the light guide plate 20 is 1.2 mm, and the distance from the center of the CCFL 40 to the light guide plate 20 is 1.7 mm,

The radians of 40.

For example, as shown in Fig. 7, an auxiliary line, defined as R, is used to calculate the radiance value and the angle value θ of the CCFL 40. According to the current 18.5-inch display product, the length of the light guide plate 20 along the length direction of the CCFL 40 is 210 mm, and the following can be obtained:

210 ² + ( R-0.5 ) ² =R ² 1;

Arctan9=210/R 2;

Through the above two formulas, we can get θ=0.273°; from the conversion relationship between the angle value and the radians value, we can get the arc of 0.00476.

Preferably, along the length direction of the CCFL 40, the thickness of the light guide plate 20 may be increased from the intermediate position to both ends.

Fig. 8 is a graph showing the relationship between the thickness of the light guide plate 20 and the light efficiency of the incident light, which is the thickness of the side of the CCFL of the light guide plate 20. As can be seen from FIG. 8, when the thickness of the light guide plate 20 is 6 mm, the light efficiency is about 65%, and when the thickness of the light guide plate 20 is 6.2 mm, the light efficiency is about 74%, and thus the thickness of the light guide plate 20 is known. When it is large, the light efficiency is high.

As can be seen from the above description, in order to improve the uniformity of the brightness of the backlight module, the thickness of the light guide plate 20 can be changed, and in particular, the thickness of both ends of the side of the CCFL of the light guide plate 20 along the length direction of the CCFL 40 can be increased. Therefore, the luminous fluxes of the CCFL 40 at both ends and the intermediate portion into the light guide plate are the same.

It should be noted that the thickness of the light guide plate 20 is set according to actual needs, and is not limited herein. In order to make better use of the light emitted by the CCFL 40, preferably, the backlight module can also The lampshade 50 is disposed around the CCFL 40. The lampshade is preferably U-shaped. To further improve light utilization, the reflector 50 may be provided with a reflective layer near the surface of the CCFL, or the lampshade may be a reflective lampshade.

As shown in FIG. 9 , the backlight module includes: a bottom reflective sheet 10 , a light guide plate 20 disposed on the bottom reflective sheet, and an optical film 30 disposed above the light guide plate. The CCFL 40 on at least one side of the light panel, and the U-shaped lamp cover 50 surrounding the CCFL 40. A reflective layer may be disposed on the face of the lamp cover 50 adjacent to the CCFL 40, or the lamp cover 50 may be a reflective lamp cover.

The shape of the CCFL 40 is curved, and the distance from the two ends of the CCFL 40 to the light guide plate 20 is smaller than the distance from the intermediate position of the CCFL 40 to the light guide plate 20.

It should be noted that, in the drawings of all the embodiments of the present invention, the CCFL 40 is disposed on one side of the light guide plate 20 as an example, but the embodiment of the present invention is not limited thereto. For example, CCFL can be placed on opposite sides of a rectangular light guide, and CCFL can even be placed on all four sides of a rectangular light guide.

The embodiment of the present invention provides a backlight module, the backlight module includes a light guide plate 20, a CCFL 40 disposed on a side of the light guide plate, and a U-shaped lamp cover 50 surrounding the CCFL; The shape of 40 is curved, and the distance from the two ends of the CCFL 40 to the light guide plate 20 is smaller than the distance from the intermediate position of the CCFL 40 to the light guide plate 20; thus, the two ends of the CCFL 40 are The distance between the light guide plates 20 is shortened, thereby improving the brightness of the two ends of the backlight module, and solving the problem of the angle-dependent brightness uniformity in the TCO, thereby improving the uniformity of the brightness of the backlight module.

The embodiment of the invention further provides a display device comprising the above backlight module.

The display device may be, for example, a liquid crystal display device, and may be a product or a component having any display function such as a liquid crystal display, a liquid crystal television, an electronic paper, an OLED display panel, a digital photo frame, a mobile phone, or a tablet computer.

It should be noted that the illumination of the CCFL itself is not affected by the light guide plate. The above "brightness of the CCFL 40" or the like refers to the brightness on the side of the light guide plate, that is, the brightness entering the light guide plate.

The above is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims.

Claims

claims

1. A backlight module, including: a light guide plate, at least one CCFL provided on at least one side of the light guide plate;

Wherein, the distance from both ends of the CCFL to at least one side of the light guide plate is smaller than the distance from the middle position of the CCFL to at least one side of the light guide plate.

2. The backlight module according to claim 1, wherein the CCFL is arc-shaped.

3. The backlight module according to claim 1 or 2, wherein the distance between both ends of the CCFL and at least one side of the light guide plate is equal.

4. The backlight module according to any one of claims 1 to 3, wherein at least one side of the light guide plate is along the length direction of the CCFL, and the thickness of the light guide plate increases from the middle position to both ends.

5. The backlight module according to any one of claims 1 to 4, further comprising: a lampshade surrounding the CCFL.

6. The backlight module according to claim 5, wherein the lampshade is U-shaped.

7. The backlight module according to claim 5 or 6, wherein the surface of the lampshade close to the CCFL is provided with a reflective layer or the lampshade is a reflective lampshade.

8. The backlight module according to any one of claims 1 to 7, further comprising: a bottom reflective sheet disposed below the light guide plate.

9. The backlight module according to any one of claims 1 to 8, further comprising: an optical film disposed above the light guide plate.

10. A display device, including the backlight module according to any one of claims 1 to 9.

11. The display device according to claim 10, wherein the display device is a liquid crystal display device.