CN100535720C - Structure and method for improving brightness of dark area in backlight module - Google Patents

Abstract

The invention provides a structure and a method for improving the brightness of a dark area in a backlight module, wherein corners of a light guide plate in the backlight module, which are close to lamp tube electrodes, are cut off, so that a light source can generate natural light leakage through the corner cutting area, the brightness of the dark area is improved, and the integral light output uniformity of the backlight module can be improved.

Description

Structure and method for improving brightness of dark area in backlight module

【Technical field】

The present invention relates to a structure and method for enhancing the brightness of dark areas in corners in a backlight module, in particular to a chamfered area formed on a light guide plate in a backlight module near the electrode of a lamp tube, and through this The chamfered area is a method for improving the light output uniformity of the backlight module.

【Background technique】

The backlight module is a component used to provide back light, and can be applied to products such as liquid crystal displays, mobile phone panels, film scanners, and slide projectors to provide a uniform surface light output. Referring to FIG. 1A , a schematic diagram of a three-dimensional structure of an existing side-type backlight module using L-shaped cold-cathode tubes can be seen. The backlight module 100 is mainly composed of a light guide plate (Light Guide Plate) 101, a reflector (Reflection Film) 103, two symmetrically arranged L-shaped cold cathode tubes (L-shape CCFL) 105, and a diffusion film (Diffusion Film) 107 , an optical film (Optical film) 109 and frames 111 and 113 for arranging the above components. The L-shaped cold cathode tube 105 is installed around the light guide plate 101, so that the generated light can enter the light guide plate 101 in the form of edge light, and guide the direction of light scattering through the light guide plate 101 and install it on the light guide plate 101. The cooperation of the reflector 103 under the light board 101 enables the light to be output to the upper diffuser 107 after reflection and refraction, so that the light distribution is more uniform. On the top of the diffusion sheet 107, other optical films 109 with specific functions can be arranged, such as installing a prism sheet (Prism) with a light-condensing effect to increase the directionality of light output, so that the front brightness can be improved.

Referring to FIG. 1B , it is a top perspective view of the conventional backlight module 100 in which the light guide plate 101 and the L-shaped cold cathode tube 105 are installed in the frame 113 . It can be observed from the upper perspective view that although the L-shaped cold-cathode tubes 105 arranged symmetrically in two phases are installed around the light guide plate 101, the L-shaped cold-cathode tubes 105 themselves cannot emit light at the electrodes and are covered with rubber insulation. Because of the sleeve 115, on the light output of the backlight module 100, there will be a "dark area" with insufficient brightness in the area near the electrode at the corner (such as the area circled by the dotted line 117), and the overall light output will be There are cases where left and right or up and down are uneven.

【Content of invention】

In view of the above-mentioned background of the invention, the problem of dark areas in the corner area of the backlight module near the electrode of the lamp due to insufficient brightness, the present invention provides a method for increasing the brightness of the dark area in the backlight module, the purpose of which is not only to reduce the backlight The opportunities generated by the dark area in the module can also improve the luminous efficiency of the lamp tube in the backlight module, so that the backlight module can have a flat light output with uniform brightness. On the other hand, the present invention also provides a structure of the backlight module, which not only enables the light source to enter the dark area of the corner in the backlight module and improves the uniformity of the light output of the entire backlight module, but on the other hand, the backlight module also has better cooling effect.

According to the above purpose, the present invention provides a structure and method for improving the brightness of the dark area in the backlight module. The corner of the light guide plate in the backlight module near the electrode of the lamp tube is cut off, so that the light source can be generated through the cut corner area. Due to the natural light leakage, the brightness of this dark area is improved, and the uniformity of the overall light output of the backlight module is increased; in addition, the light guide plate with chamfered areas provided by the present invention can not only see the actual lamp tube electrode position The size and shape of the chamfered corners can be adjusted according to the range and position of the chamfered corners, and at the same time, the heat dissipation in the backlight module can achieve a better effect because of the chamfered corners.

【Description of drawings】

FIG. 1A is a three-dimensional schematic diagram of a conventional backlight module.

FIG. 1B is a top perspective view of a light guide plate and a light source in a conventional backlight module.

FIG. 2A is a schematic three-dimensional structure diagram of the backlight module provided by the first preferred embodiment of the present invention.

Fig. 2B is a top perspective view of the light guide plate and the light source in the backlight module in the first preferred embodiment.

FIG. 2C is a top perspective view of the light guide plate with the rounded corner structure and the light source inside the backlight module.

FIG. 3A is a schematic three-dimensional structure diagram of a backlight module provided by a second preferred embodiment of the present invention.

Fig. 3B is a top perspective view of the light guide plate and the light source in the backlight module in the second preferred embodiment.

【Detailed ways】

The following is a detailed description of the present invention. The description of each component in the backlight module in the following description does not include a complete description of its operating principle and assembly process. The prior art used in the present invention is only cited here as an emphatic reference to help explain the present invention. Moreover, the related diagrams in the following texts are not drawn according to the actual scale, and their function is only to express the characteristics of the present invention.

According to the first preferred embodiment of the present invention, a method and structure are provided for enhancing the brightness of the dark area in the inner corner of the backlight module. Referring first to FIG. 2A , it is a schematic diagram of the three-dimensional structure of the backlight module of the present invention. The backlight module 200 is mainly composed of a flat light guide plate 201 , a reflector 203 , a light source 205 , a diffuser 207 , an optical film 209 and frames 211 and 213 for arranging the above components. The light source 205 is selected from two symmetrically arranged L-shaped cold cathode tubes, and is installed around the light guide plate 201, so that the generated light can enter the light guide plate 201 in the way of end surface illumination (this embodiment adopts a side-entry type light source) Incidence mode), and through the light guide plate 201 to guide the direction of light scattering and the cooperation of the reflector 203 installed under the light guide plate 201, the light is output to the upper diffuser 207 after reflection and refraction to make the light distribution more uniform. Other optical films 209 with specific functions can be arranged above the diffusion sheet 207 .

Also refer to FIG. 2B , which is a top perspective view of the light guide plate 201 in the backlight module 200 and the L-shaped cold cathode tube 205 installed in the frame 213 . It can be clearly observed from the upper perspective view that one of the features of the backlight module 200 provided by the present invention is the electrode part of the light guide plate 201 close to the light source 205 (not shown in the figure, because it is surrounded by the insulating sleeve 215) The corners of the light guide plate 201 are cut off, so that the position of the light guide plate 201 near the corners of the dark area (such as the area circled by the dotted line 217) has a chamfered shape. In this way, the light emitted by the light source 205 can pass through the chamfered area of the light guide plate 201 to cause natural light leakage, and the light in this dark area can also be reflected by the reflector 203 and then enter the diffusion sheet 207 above the light guide plate 201 Subsequent processing is performed; therefore, the brightness of the dark area can be compensated, so that the overall light output of the backlight module can be uniform.

In this embodiment, the corner of the light guide plate 201 close to the electrode of the light source 205 is a prismatic guide angle, but the shape of the chamfered corner of the light guide plate 201 is not limited to this, refer to the one circled by the dotted line 219 in FIG. 2C range, the light guide plate 201 can also have a circular arc-shaped rounded corner; and other chamfered areas formed on the light guide plate 201 corresponding to the dark area can also be implemented according to the present invention, as long as it can provide reflection There is a direct connection structure between the element 203 and the diffuser 207 to achieve the effect of natural light leakage, and also allow the backlight module 200 to have an additional space for heat dissipation.

According to the second preferred embodiment of the present invention, there is provided a method and structure for enhancing the brightness of the dark area in the inner corner of the backlight module. Referring first to FIG. 3A , it is a schematic diagram of the three-dimensional structure of the backlight module of the present invention. The backlight module 300 is mainly composed of a wedge-shaped light guide plate 301, a reflector 303, a light source 305, a peripheral reflector (not shown in the figure), a diffuser 307, an optical film 309 and a frame for arranging the above components Composed of 311 and 313. The light source 305 can be a cold cathode tube, which is installed on the end face (light incident surface) of the thick side of the wedge-shaped light guide plate 301, so that the generated light can enter the wedge-shaped light guide plate 301 in the manner of illuminating the end face (this embodiment adopts a side-type light source incident mode), through the wedge-shaped shape of the wedge-shaped light guide plate 301 and the cooperation of the reflector 303, the light is output to the upper diffuser 307 after reflection and refraction to make the light distribution more uniform. Other optical films 309 with specific functions may also be arranged above the diffuser 307 .

Referring to FIG. 3B at the same time, it is a top perspective view of the wedge-shaped light guide plate 301 in the backlight module 300 and the light source 305 installed in the frame 313 . It can be clearly observed from this figure that one of the features of the backlight module 300 provided by the present invention is that the electrode part of the wedge-shaped light guide plate 301 is close to the light source 305 (not shown in the figure, because it is surrounded by the insulating sleeve 315) The corners of the wedge-shaped light guide plate 301 are cut off, so that the wedge-shaped light guide plate 301 has a chamfered shape near the corner of the dark area (such as the range circled by the dotted line 319) (in this embodiment, the chamfered shape is selected from a rounded corner. structure). In this way, the light emitted by the light source 305 can pass through the chamfered area of the wedge-shaped light guide plate 301 to produce natural light leakage, and the light in the dark area of the corner can also enter the wedge-shaped light guide plate 301 after being reflected by the reflector 303 The upper diffuser 307 performs subsequent processing; therefore, the brightness of the dark area can be compensated, so that the overall light output of the backlight module can be uniform.

From the above-mentioned first and second preferred embodiments of the present invention, it can be seen that the shape of the chamfered corners of the light guide plate provided by the present invention can be prismatic or arc-shaped. Rounded corners or other shapes, and can also be formed on flat and wedge-shaped light guide plates, so regardless of whether the light tubes used in this backlight module are linear (a rectangular light source composed of four linear light tubes) , or a single linear lamp), U-shaped, C-shaped and L-shaped lamps, as long as the chamfered area can be formed on the corner or side of the light guide plate near the electrode of the lamp to achieve the effect of natural light leakage, and Maximize the luminous efficiency of the lamp tube; and the present invention is not limited only to the side-type light source incident mode (the light incident surface of the light guide plate and the light output surface have a vertical angle), other such as direct-type backlight modules (The light incident surface of the light guide plate is parallel to the light output surface) can also be implemented according to the present invention.

To sum up, the method for improving the brightness of the dark area in the backlight module provided by the present invention is to first emit at least one light source (including linear, U-shaped, L-shaped and C-shaped lamp tubes, etc.) into a light incident light guide plate. surface (including flat and wedge-shaped light guide plates); then the light can be guided by the light guide plate and then exported from the light output surface of the light guide plate. However, since the electrode part of the lamp tube cannot emit light and is covered with an insulating sleeve, there will be a dark area with insufficient brightness in the light guide plate near the electrode part of the lamp tube, which will reduce the light output uniformity of the overall backlight module. The present invention proposes to form a chamfered structure in the position corresponding to these dark areas in the light guide plate (for example, if two symmetrical L-shaped lamp tubes are used, the light guide plate can form a chamfered angle at two opposite corners near the electrode. area; and if the position corresponding to the lamp tube electrode in the light guide plate is not in the corner, you can also choose to form a concave groove structure on the side of the light guide plate to achieve the effect of natural light leakage), so that the so-called The light in the dark area can directly pass through the chamfered area, and spread out through reflection or direct emission (such as reflection through the reflector or directly entering the diffusion sheet above the light guide plate, etc.), so that these functions in the backlight module can be improved. The overall uniformity of light output can be improved by reducing the brightness of dark areas.

Claims (10)

1. A backlight module, comprising: A light guide plate comprising a light output surface and a light incident surface; and A light source, wherein the light source is a lamp tube, has a light source electrode and another light source electrode, the light source is arranged beside the light incident surface of the light guide plate, and the light guide plate has a A chamfer. 2. The backlight module according to claim 1, wherein the shape of the chamfered corner is a chamfered corner. 3. The backlight module according to claim 1, wherein the shape of the chamfered corner is a rounded corner. 4. The backlight module according to claim 1, wherein the light guide plate is a flat light guide plate. 5 . The backlight module according to claim 1 , wherein the light guide plate adopts a side-type incident light source. 6 . 6 . The backlight module according to claim 1 , wherein the light source is composed of four linear light tubes and arranged around the light guide plate. 7 . The backlight module according to claim 1 , wherein the light guide plate adopts a direct light incident mode. 8 . 8. The backlight module according to claim 1, wherein the light guide plate is a wedge-shaped light guide plate. 9. The backlight module according to claim 1, wherein the module further comprises a reflector disposed on the side of the light guide plate opposite to the light output surface, so that the light refracted from the side of the light guide plate The light can be reflected back into the light guide plate through the reflector. 10. The backlight module according to claim 1, wherein the light source is a cold cathode tube.

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