Backlight module and liquid crystal display incorporating same

Disclosed are a backlight module and a liquid crystal display (LCD) incorporating the same. The backlight module includes a frame having an accommodation portion, elastic plate structures, a light guide plate disposed in the frame and light emitting diodes (LEDs). The elastic plate structures extend respectively from both sides of the accommodation portion in the frame. The light emitting diodes are disposed in the accommodation portion, and are fixed between the light guide plate and the respective elastic plate structures.

RELATED APPLICATIONS

This application claims priority to Taiwan Patent Application Serial Number 96131813, filed Aug. 28, 2007, which is herein incorporated by reference.

BACKGROUND

1. Field of Invention

The present invention relates to a backlight module and a liquid crystal display (LCD) incorporating the same, and more particularly, to a backlight module having a positioning structure and to an LCD including the backlight module.

2. Description of Related Art

A backlight module is one the fundamental parts of an LCD. Since the LCD itself does not emit light, the backlight module is needed to provide the required light source. In the backlight module, a light guide plate is used to direct the light emitted from a backlight source as a planar light source, thereby assuring the uniformity of lightness. A backlight commonly used in the backlight module can be such as a cold cathode fluorescent lamp (CCFL) and a light emitting diode (LED), etc. Although the CCFL is the main trend currently, the demands for using the LED have been increasing daily. In comparison with the CCFL, the LED has the advantages of environmental protection, small size, long operation life, low driving voltage, low power consumption and excellent shock resistance, etc.

In general, when light emitting diodes are applied in an LED backlight module, the light emitting diodes are first disposed on a flexible print circuit board (FPC), and then the flexible print circuit board is folded and inserted into a mold frame for disposing the light emitting diodes adjacent to one side of a light guide plate. Meanwhile, the distance and angle between the light emitting diodes and the light guide plate has quite a great influence on the output luminance and lightness uniformity of the light guide plate, thus affecting the quality of the backlight module, further determining if the LCD using the backlight module is with good quality. Hence, how to accurately position the light emitting diodes to closely contact the light guide plate has become quite an important issue.

Conventional skills intend to make the assembly of the light emitting diodes (or an FPC) and the module to meet the requirement of high accuracy by using specific assembling methods, tape adhesion or the design of positioning the FPC, etc. However, the conventional skill using specific assembling methods cannot actually demand all of the workers to have consistent assembling movements. Especially in mass production, the assembling movements among the works will be different, and it is difficult to establish the standards for determining if the assembling movements are consistent. Further, the conventional skill using tape adhesion causes the increase of the production cost, and not all of the related product mechanisms have sufficient space for receiving the tape for adhesion. If the adhesive area of the tap is not enough, the light emitting diodes will be displaced easily. Further, the conventional skill using the design of positioning the FPC has the following disadvantages. While the product is increasingly miniatured, the FPC or mold frame may not have enough space for forming holes, pillars and ribs to fabricate a positioning device; and the positioning device must have certain tolerances, and thus the assembly of the light emitting diodes (or an FPC) and the module fails to meet the requirement of high accuracy.

SUMMARY

Hence, an aspect of the present invention is to provide a backlight module and an LCD including the same for accurately positioning light emitting diodes to closely contact a light guide plate by directly forming positioning structures on a frame without causing extra production cost.

An embodiment of a backlight module comprises a frame, a first elastic plate structure, a light guide plate and a first LED. The frame has an accommodation portion, and the first elastic plate structure extends from a first side of the accommodation portion. The light guide plate is disposed in the frame, and the first LED is disposed in the accommodation portion and fixed between the light guide plate and the first elastic plate structure.

In another embodiment, a first surface of the first LED contacts the first elastic structure. The first elastic plate structure has a protrusive structure, and the protrusive structure is engaged with a recess portion of the first surface of the first LED.

In still another embodiment, a first surface of the first LED contacts the first elastic plate structure, the first LED having a second surface, and a corner is formed between the first surface and the second surface, and the first elastic plate structure resists the corner.

In yet another embodiment, there is an angle between the first elastic plate structure and the first side of the accommodation portion facing towards the first LED, and the angle is substantially greater than or equal to 90 degrees.

The aforementioned embodiments of the backlight module may further comprise a second elastic plate and a second LED, wherein the second elastic plate structure extends from a second side of the accommodation portion opposite to the first side, and the second LED is disposed in the accommodation portion and fixed between the light guide plate and the second elastic plate structure. The structures of the second elastic plate structure and the second LED are similar to those of the first elastic plate structure and the first LED.

In one embodiment, the first elastic plate structure is connected to the second elastic structure.

The aforementioned embodiments of the backlight module may further comprise at least one third LED disposed between the first LED and the second LED. The first LED, the second LED and the third LED are disposed on the FPC, and the FPC is folded and inserted into the accommodation portion.

Further, an LCD of the present invention comprises the aforementioned backlight module.

Hence, the application of the present invention can form positioning structures directly on a frame without causing extra production cost; enhance the stability of module assembling; provide stable light source for improving the optical problems of lower luminance and poor lightness uniformity; provide more frame space for use since the elastic plate structures (positioning structures) occupy small space.

It is to be understood that both the foregoing general description and the following detailed description are examples, and are intended to provide further explanation of the present invention as claimed.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the present invention, elastic plate structures are directly formed a frame, thereby enabling light emitting diodes to closely contact a light guide plate and generating interference among the elastic plate structures, the light emitting diodes, and the light guide plate. Since when the elastic plate structures are formed simultaneously the frame is fabricated, no extra production cost is caused. Hereinafter, various embodiments of the present invention are described.

Referring toFIG. 1AandFIG. 1B,FIG. 1Ais a schematic diagram illustrating the structure of a backlight module according to a first embodiment of the present invention, andFIG. 1Bis schematic enlarged diagram illustrating a detail A shown inFIG. 1A. In this embodiment, the backlight module comprises a frame100, an elastic plate structure110, an elastic plate structure120, a light guide plate200, and LEDs210and220, wherein the light guide plate200is disposed in the frame100. The frame100has an accommodation portion102used for receiving the LEDs210and220. At least one LED230can be disposed between the LED210and the LED220. The LEDs210,220and230are disposed on an FPC250. The elastic plate structures110and120extend respectfully from both sides104and106of the accommodation portion102of the frame100. When the backlight module is assembled, a worker first folds the FPC250back into the accommodation portion102of the frame100, and then clips the LED210between the light guide plate200and the elastic plate structure110; and the LED220between the light guide plate200and the elastic plate structure120, thereby fixing the LEDs210,220and230on the desired positions, thus achieving accurately positioning.

Since the related structure between the LED210and the elastic plate structure110is similar to that between the LED220and the elastic plate structure120, only the related structure between the LED210and the elastic plate structure110is explained hereinafter. As shown inFIG. 1B, when the LED210is inserted between the light guide plate200and the elastic plate structure110, the elasticity of the elastic plate structure110can force the LED210to be tightly fit in between the light guide plate200and the elastic plate structure110, and may result in some interference among the elastic plate structure110, the LED210and the light guide plate200, so that the LED210can be naturally fixed on an appropriate position of one side of the light guide plate200.

Hence, with the design of the elastic plate structures110and120according to this embodiment, the worker does not need to worry if the LEDs210,220and230are aligned to or tightly fit to one side of the light guide plate200; and also does not need to use the method such as tape adhesion to fix the LEDs210,220and230, thus enhancing the stability of module assembling, providing stable light source, and further improving the optical problems of lower luminance and poor lightness uniformity. Besides, the lengths of the elastic plate structures110and120are merely required to be sufficient to clip the LEDs210and220, and thus the space occupied by the elastic plate structures110and120is quite small, so that more space can be provided in the frame100for use.

Although this embodiment uses two elastic plate structures110and120as an example for explanation, the present invention also may use only one elastic plate structure110or120to achieve the purpose of accurately positioning and fixing the LEDs210,220and230.

Referring toFIG. 2AandFIG. 2B,FIG. 2Ais a schematic diagram illustrating the structure of a backlight module according to a second embodiment of the present invention, andFIG. 2Bis schematic enlarged diagram illustrating a detail B shown inFIG. 2A. This embodiment uses elastic plate structures111and121to replace the elastic plate structures110and120of the first embodiment shown inFIG. 1A. In this embodiment, protrusive structures113and123are formed on the side surfaces of the elastic plate structures111and121corresponding to the LEDs110and210, so as to be engaged with the corresponding recess portions213and223formed on the LEDs210and220, thereby enhancing the fixing of the LEDs210and220. The protrusive structures113and123can be such as pillar structures or other proper structures. When the backlight module is assembled, a worker first folds the FPC250back into the accommodation portion102of the frame100, and then clips the LED210between the light guide plate200and the elastic plate structure111; and the LED220between the light guide plate200and the elastic plate structure121, and also forces the protrusive structures113and123to be engaged with the recess portions213and223, thereby fixing the LEDs210,220and230on the desired positions and achieving accurately positioning.

Since the related structure between the LED210and the elastic plate structure111is similar to that between the LED220and the elastic plate structure121, only the related structure between the LED210and the elastic plate structure111is explained hereinafter. As shown inFIG. 2B, a surface212of the LED210contacts the elastic plate structure111. When the LED210is inserted between the light guide plate200and the elastic plate structure111, the elasticity of the elastic plate structure111can force the LED210to be tightly fit in between the light guide plate200and the elastic plate structure111, and the protrusive structure113of the elastic plate structure111is engaged with the recess portion213of the LED210, so that the LED210can be reinforcedly fixed on an appropriate position of one side of the light guide plate200. Besides, the LED210has a surface214, and a corner215is formed between the surface214and the surface212, and the elastic plate structure111resists the corner215.

Hence, except the aforementioned advantages of the first embodiment, with the use of the elastic plate structures111and121having the protrusive structures113and123according to this embodiment, the LED210and the LED220can be fixed reinforcedly.

Similarly, although this embodiment uses two elastic plate structures111and121as an example for explanation, the present invention also may use only one elastic plate structure111or121to achieve the purpose of accurately positioning and fixing the LEDs210,220and230.

Referring toFIG. 3AandFIG. 3B,FIG. 3Ais a schematic diagram illustrating the structure of a backlight module according to a third embodiment of the present invention, andFIG. 3Bis schematic enlarged diagram illustrating a detail C shown inFIG. 3A. This embodiment uses elastic plate structures115and125to replace the elastic plate structures110and120of the first embodiment shown inFIG. 1A. In this embodiment, there are angles between the elastic plate structures115and125and both sides104and106of the accommodation portion102of the frame100facing towards the LEDs210and220, and the angles are greater than 90 degrees, and in the first embodiment, the angles similar thereto are about equal to 90 degrees.

Since the related structure between the LED210and the elastic plate structure115is similar to that between the LED220and the elastic plate structure125, only the related structure between the LED210and the elastic plate structure115is explained hereinafter. As shown inFIG. 3B, a surface212of the LED210contacts the elastic plate structure115. When the LED210is inserted between the light guide plate200and the elastic plate structure115, the elastic plate structure115can resist an corner117having an angle A formed by the elastic plate structure115and the side104, wherein the angle A is about greater than 90 degrees, so that the LED210can be fixed between the light guide plate200and the elastic plate structure115.

Hence, except the aforementioned advantages of the first embodiment, the elastic plate structures115and125of this embodiment require smaller space, and thus more space in the frame100can be saved for use.

Similarly, although this embodiment uses two elastic plate structures115and125as an example for explanation, the present invention also may use only one elastic plate structure115or125to achieve the purpose of accurately positioning and fixing the LEDs210,220and230.

Referring toFIG. 4,FIG. 4is a schematic diagram illustrating the structure of a backlight module according to a fourth embodiment of the present invention. This embodiment uses an elastic plate structure180to replace the elastic plate structures110and120of the first embodiment shown inFIG. 1A, wherein the elastic plate structure180connects both sides104and106of the accommodation portion102of the frame100together, i.e. the elastic plate structures110and120of the first embodiment are connected. The advantages and function of this embodiment are similar to those of the first embodiment, and thus are not stated herein again.

Besides, the backlight module of the present invention can be applied in an LCD.

It can be known from the embodiments described above, the present invention has the advantages of avoiding the extra production cost; enhancing the stability of module assembling and providing stable light source, thereby improving the optical problems of lower luminance and poor lightness uniformity; and providing more frame space for use.