Backlight module

A backlight module includes a light source, a light guide plate and at least one optical film. The light source has a plurality of light emitting devices. The light guide plate includes a light entrance portion, a main body portion and at least one positioning structure. The light entrance portion has a top surface and a light entrance surface. The light source is disposed corresponding to the light entrance surface. The top surface is adjacently connected to the light entrance surface. The main body is connected to the light entrance portion and has a first light extraction surface connecting the top surface. The positioning structure is disposed on the top surface and corresponding to an interval between two adjacent light emitting devices, and has an accommodating space. The optical film is disposed above the light guide plate and has at least one protruding portion disposed in the accommodating space.

TECHNICAL FIELD

The present invention relates to a backlight module, and more particularly to a backlight module having a positioning structure for optical films.

BACKGROUND

While electronic industry keeps developing, liquid crystal displays (LCDs) have become the mainstream of present market. Since the LCD panel is not a self-emitting device, a backlight module is needed to provide light to the LCD panel, thus achieving the purpose of image displaying.

According to some requirements coming from the market, the design trend of bezel for LCD module is towards narrower and the LCD module keeps enlarging its size and widening its viewing angle. Such requirements have to be taken into the consideration on designing of the components in the backlight module. For example, in order to install optical films to the backlight module, positioning structures (such as fixing corners) are disposed on the frame of the backlight module for fixing and positioning the optical films, and avoiding the displacement of the optical films which leads to downgrade of the optical performance.

However, the above mentioned fixing corners on the frame are usually located at two sides of the LCD module. When the backlight module is illuminating, shadows are formed by the fixing corners on the two sides of the screen of the LCD module. Such shadows directly affect the displaying quality of the LCD module.

SUMMARY

The present invention provides a backlight module including a light source, a light guide plate and at least one optical film. The light source has a plurality of light emitting devices. The light guide plate includes a light entrance portion, a main body portion and at least one positioning structure. The light entrance portion has a top surface and a light entrance surface. The light source is disposed corresponding to the light entrance surface. The top surface is adjacently connected to the light entrance surface. The main body portion is connected to the light entrance portion and has a first light extraction surface, and the first light extraction surface is connected to the top surface. The at least one positioning structure is disposed on the top surface of the light entrance portion. The positioning structure is disposed corresponding to an interval between two adjacent light emitting devices. The positioning structure has an accommodating space. The at least one optical film is disposed above the light guide plate. The optical film has at least one protruding portion disposed in the accommodating space.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring toFIG. 1, which is a top view of a backlight module according to an embodiment of the present invention. AsFIG. 1shows, the backlight module1includes a light source10, a light guide plate11and at least one optical film12. The light source10has a plurality of light emitting devices100. The light guide plate11includes a light entrance portion110, a main body portion111and at least one positioning structure112. The light entrance portion110has a top surface1101and a light entrance surface1102. The light source10is disposed corresponding to the light entrance surface1102. The top surface1101is adjacently connected to the light entrance surface1102. The main body portion111is connected to the light entrance portion110. The main body portion111has a first light extraction surface1110. The first light extraction surface1110is connected to the top surface1101of the light entrance portion110. The positioning structure112is arranged on the top surface1101of the light entrance portion110. The positioning structure112is disposed corresponding to an interval between two adjacent ones of the light emitting devices100. The positioning structure112has an accommodating space1120. The optical film12is disposed above the light guide plate11. The optical film12has at least one protruding portion120. The protruding portion120is disposed in the accommodating space1120of the positioning structure112.

In this embodiment of the backlight module1, since the positioning structure112is disposed corresponding to the interval between the two adjacent ones of the light emitting devices100, the structure design has an advantage that the positioning structure112does not block the light emitted from the light emitting device100, thus avoiding the shadows formed by the positioning structure112blocking the light emitted from the light emitting device100.

Following the mentioned above, asFIG. 1shows, the optical film12of this embodiment further has a base plate121. The base plate121has a second light extraction surface122and a side surface123connecting to the second light extraction surface122. The protruding portion120of the optical film12is, for example, located at the side surface123, but not limited thereto in the present invention. Besides, the number of the protruding portions120of the optical film12is four in this figure. For accommodating the protruding portions120, the number of the positioning structures112is also four in this figure, but not limited thereto in the present invention. The increase and decrease of the number of the positioning structures112depend on the number of the protruding portions120. In other words, if the number of the protruding portion120is one, then the number of the positioning structure112is also one.

Referring toFIG. 2, which is a magnified view of an area circled by dashed line Z inFIG. 1. AsFIG. 2shows, the positioning structure112further has a first surface1121, a second surface1122and a third surface1123. The second surface1122and the third surface1123respectively extend from two ends of the first surface1121and along the direction toward the main body portion111of the light guide plate11. The first surface1121, the second surface1122and the third surface1123of the positioning structure112define the accommodating space1120. AsFIG. 2shows, in this embodiment, the first surface1121, the second surface1122and the third surface1123of the positioning structure112are, for example, in a U-shaped arrangement.

Referring toFIG. 3, which is a cross sectional view along a line A-A inFIG. 1. AsFIG. 3shows, in this embodiment of the backlight module1, the light entrance portion110further has a bottom surface1103opposite to the top surface1101. The distance between the bottom surface1103and the top surface1101for example gradually decreases along the direction E away from the light entrance surface1102. For example, asFIG. 3shows, the distance between a point B on the top surface1101of the light entrance portion110and the bottom surface1103of the light entrance portion110is D1, and the distance between a point C on the top surface1101of the light entrance portion110and the bottom surface1103of the light entrance portion110is D2. As can be clearly seen inFIG. 3, the distance D1between the top surface1101of the light entrance portion110and the bottom surface1103is greater than the distance D2. The distance D1between the top surface1101of the light entrance portion110and the bottom surface1103gradually decreases to the distance D2along the direction E away from the light entrance surface1102. More specifically, the top surface1101of the light entrance portion110is, for example, an inclined surface. The shape of the light entrance portion110inFIG. 3is merely one of the embodiments of the present invention, and not limited thereto in the present invention.

Please refer toFIG. 2andFIG. 3again. AsFIG. 3shows, the positioning structures112of this embodiment, for example, protrude from the top surface1101of the light entrance portion110. AsFIG. 2shows, the width of the positioning structure112gradually decreases along the direction E away from the light entrance surface1102. For example, asFIG. 2shows, the length of the line segment I-J represents the first width W1of the positioning structure112and the length of the line segment G-H represents the second width W2of the positioning structure112. As can be clearly seen inFIG. 2, the first width W1of the positioning structure112is greater than the second width W2. The first width W1of the positioning structure112gradually decreases to the width W2along the direction E away from the light entrance surface1102. The shape of the positioning structure112is merely one of the embodiments of the present invention, and not limited thereto in the present invention.

In order to more clearly show the structure of every components of the backlight module1and the positioning relationship thereof in this embodiment, the structure of the backlight module1of this embodiment can be referred to a three dimensional view inFIG. 4. It should be mentioned that in this figure, in order to clearly demonstrate the outer appearance of the positioning structure112and the positioning relationship between the positioning structure112and the other components, the optical film12is omitted. The connecting relationship between the optical film12and the positioning structure112can be specifically described inFIG. 1and other embodiments below.

Referring toFIG. 5AandFIG. 5B,FIG. 5Ais a top view of the backlight module according to another embodiment of the present invention.FIG. 5Bis top view showing each one of the optical films inFIG. 5A. The backlight module1aof this embodiment is similar to the backlight module1inFIG. 1. The difference is that, as shows inFIG. 5B, the backlight module1aof this embodiment includes a plurality of optical films12a,12b, and12c. The dimensions of the optical films12a,12b, and12care, for example, substantially the same. The optical films12a,12b, and12chave protruding portions120a,120b, and120c, respectively. AsFIG. 5Ashows, the backlight module1aof this embodiment includes positioning structures112a,112b, and112c. The optical films12a,12b,12care sequentially stacked from bottom to top on the light extraction surface1110of the light guide plate11(the optical film12cis the top optical film). The protruding portion120aof the optical film12ais disposed in the accommodating space1120aof the positioning structure112a. The protruding portion120bof the optical film12bis disposed in the accommodating space1120bof the positioning structure112b. The protruding portion120cof the optical film12cis disposed in the accommodating space1120cof the positioning structure112c. In other words, the accommodating space of one of the positioning structures112a,112band112conly accommodates the protruding portion of one of the optical films12a,12band12c. Therefore, after the optical films12a,12band12care sequentially stacked, it can be clearly recognized that the protruding portions120a,120band120cof the optical films12a,12band12care respectively and securely fixed by the positioning structures112a,112band112c. There is not any one of the optical films which is neglected to be fixed. The other components in this figure are the same asFIG. 1shows and thus not repeated herein.

Referring toFIG. 6AandFIG. 6B,FIG. 6Ais a top view of the backlight module according to another embodiment of the present invention.FIG. 6Bis a cross sectional view along a line K-K inFIG. 6A. AsFIG. 6Bshows, the backlight module1bof the embodiment is similar to the backlight module1inFIG. 1. The difference is that the positioning structure112dof the backlight module1bfurther has a fourth surface1124. The fourth surface1124is connected to the first surface1121, the second surface1122and the third surface1123(the second surface1122and the third surface1123shown asFIG. 2). The fourth surface1124overlaps the protruding portion120of the optical film12. The advantage of the fourth surface1124of the positioning structure112dof this embodiment is that when the protruding portion120of the optical film12is disposed in the accommodating space1120of the positioning structure112d, since the fourth surface1124overlaps the protruding portion120of the optical film12, the optical film12is more firmly fixed on the first light extraction surface1110of the light guide plate11.

Referring toFIG. 7, which is a top view of the backlight module according to another embodiment of the present invention. AsFIG. 7shows, the backlight module1cis similar to the backlight module1inFIG. 1. The difference is that the light guide plate11cof the backlight module1cfurther includes a plurality of protruding structures13. The protruding structures13are disposed on the light entrance surface1102of the light entrance portion110. Each one of the light emitting devices100of the light source10is located between two adjacent ones of the protruding structures13.

In conclusion, the backlight module disclosed by the embodiments of the present invention, in which the light guide plate has at least one positioning structure. The positioning structure is disposed on the top surface of the light entrance portion of the light guide plate, and the positioning structure is disposed corresponding to the interval between two adjacent ones of the light emitting devices. Under this structural design, the protruding portions of the optical films can be directly disposed in the accommodating spaces of the positioning structures. There is no need to dispose a position structure on the frame for fixing the optical film. Moreover, since the positioning structure is disposed corresponding to the interval between two adjacent ones of the light emitting devices, the positioning structures do not block the light emitted from the light emitting devices. Therefore, the shadows formed by the positioning structure on the frame can be avoided, the function of the alignment in assembly can be remained and the displacement of the optical films can be avoided.