CN100386681C - LED backlight module - Google Patents

Abstract

The LED backlight module comprises a diffusion plate, at least one optical element, at least one light emitting diode and a reflector plate, wherein the optical element is arranged below the diffusion plate and is provided with a high-reflectivity reflection surface, the light emitting diode is arranged below the optical element, the reflector plate is arranged below the light emitting diode and at the side edge of the whole module, the optical element for controlling the LED light distribution curve guides light emitted by the LED to a specific direction, the light is not directly emitted from the front side of the LED, and the effects of color mixing and homogenization are further achieved; the LED backlight module provided by the invention achieves the effects of color mixing and uniform light emitting, and meanwhile, the LED backlight module which is simple in structure and easy to manufacture is provided, the manufacturing cost can be reduced, the industrial utilization value is improved, and various problems derived from the prior art are solved.

Description

LED backlight module

technical field

The present invention relates to a backlight module, in particular to a backlight module using a light emitting diode (Lightemitting diode, LED) as a light source.

Background technique

According to the Display Technology Research (Display Search) report, the market will have a strong demand for LCD TVs (LCD TV) in the next few years, and it is estimated that the demand for LCD TVs will reach at least 16.24 million units in 2006. It has opened up huge business opportunities, among which the backlight module is one of the key development projects. Under the trend of environmental protection and thinness, the backlight in the backlight module is gradually replaced by a cathode tube (Cold cathode fluorescent lamp, CCFL) to a light emitting diode (LED). The form is transformed into an LED similar to a point light source.

Therefore, in the development of the next-generation backlight source, since the backlight module using LED light source has the characteristics of high fineness, high luminance, mercury-free, high color reproducibility, etc., it can endow the LCD panel with higher added value, while in the past LED It always gives people the impression of saving space. Therefore, it is generally believed that the application of LED backlight modules in the future will cross the threshold of portable electronic products and quickly extend to industries such as automobiles, advertising light boxes, monitors, televisions, video, information, communications, home appliances, and consumer products. At the same time, the biggest challenge facing using LEDs as backlights is how to evenly diffuse single-point, monochromatic LEDs to the entire screen to achieve uniform color and brightness effects. Related patent technologies such as US Patent No. 5,499,120 and US Patent Publication No. 2005/0001537 and other cases.

Take US Pat. No. 5,499,120 as an example. In this patent, LEDs with relatively large light emitting angles are arranged in a matrix and used as a backlight source for LCDs. However, since the LEDs of this backlight module are arranged regularly and do not include any optical elements to control the light distribution curve of the LEDs, color mixing cannot be performed. Therefore, this patented technology is only applicable to a single-color light source, and cannot achieve the effect of colorization.

Looking at U.S. Patent Publication No. 2005/0001537, this patent proposes the technology of using the Total Internal Reflection (TIR) principle on the LED, and designs a special optical element structure that satisfies the total reflection angle. The light source emitted by the LED grain is guided to the side emitter (Side Emitter), so as to achieve the effect of color mixing and uniformity.

However, the optical element structure used in this patent must meet the critical angle condition of the TIR principle, so the design is too complicated, and the optical element structure only allows a very small tolerance; therefore, not only the mold opening structure is complicated, but also the production is more difficult. Furthermore, because multiple molds must be opened for manufacturing, the cost remains high.

At the same time, the conditions for satisfying the TIR principle are quite harsh. As long as there is a slight error between the position of the LED crystal grain and the relative position of the TIR surface, the light will radiate from the front. Therefore, the products produced during the actual implementation of this patented technology cannot guide all the light to the side to emit light, resulting in poor light uniformity.

In addition, because the LED under the structure of this patented technology still has a little light exposed from the front, it is necessary to install two diffusers in the design of the entire module to improve the uniformity of light output, and an additional small LED must be added directly above the LED. The spot reflectors in the area are completely blocked to meet the critical angle condition and perform total reflection; in other words, this patent must stack quite a few layers of components to improve the problem of poor light uniformity. Therefore, the LED backlight module using this patented technology has problems such as complex structure, difficulty in manufacturing, and high cost, which is not conducive to industrial utilization, and there are still some points to be improved.

Since the above-mentioned existing technologies have problems such as inability to colorize, poor uniformity of light output, complex structure, difficult manufacture, high cost, and no industrial application value, how to produce a backlight module with a simple structure, easy manufacture, and low cost , and have better color mixing and homogenization effects, solve the problems derived from the prior art, and become a problem that needs to be solved at present.

Contents of the invention

In order to overcome the above-mentioned shortcomings of the prior art, the main purpose of the present invention is to provide an LED backlight module that improves the effects of color mixing and uniformity.

Another object of the present invention is to provide an LED backlight module with simple structure and easy manufacture.

Another object of the present invention is to provide an LED backlight module that can reduce manufacturing costs.

Another object of the present invention is to provide an LED backlight module that can increase the industrial utilization value.

In order to achieve the above and other objectives, the present invention provides an LED backlight module, the LED backlight module includes a diffuser plate, at least one optical element with a reflective surface with high reflectivity arranged under the diffuser plate, at least one correspondingly arranged on the optical element The light-emitting diode under the element and the reflection sheet arranged under the light-emitting diode and on the side of the whole module.

The optical element is a structure made of high light transmittance material, wherein the high light transmittance material is plastic or glass. The reflective surface of the optical element can optionally have a metal layer or a dielectric layer, wherein the metal layer can be, for example, a structure formed by evaporation or sputtering, and the dielectric layer can be, for example, a stack of multilayer dielectric materials. constituted structure. The metal layer is a structure formed by sputtering silver or aluminum on the reflective surface of the optical element made of plastic; the dielectric layer can be made by stacking the reflective surface of the optical element made of _TiO2 on the glass constituted structure.

At the same time, the reflective surface has a geometric cross-section, wherein, for example, the reflective surface is a combination of V-shaped, arc-shaped, perfect circle, elliptical or zigzag-shaped cross-sections. Preferably, the reflective surface with V-shaped section and the light-emitting diode form an included angle of 1 to 60 degrees. In addition, the LED backlight module of the present invention may include a plurality of relative numbers of optical elements and light-emitting diodes, and the light-emitting diodes may be, for example, any permutation and combination of red, green, and blue LEDs, and the light-emitting diodes may also be white light-emitting diodes. .

In addition, the LED backlight module may also include a brightness enhancement film (Brightness Enhancement Film, BEF) arranged above the diffuser plate, the brightness enhancement film is made of materials such as Polyester or Polycarbonate A film or sheet used to condense light and increase brightness.

The present invention can provide a direct-lit LED backlight module, in which red, blue, green and other multi-color LEDs are arranged directly under the liquid crystal panel in a staggered arrangement, and the reflection sheets on the bottom and sides of the backlight module can The light source is reflected into the LCD panel, and each LED has an optical element that can control the LED light distribution curve. Therefore, due to the high reflectivity of the reflective surface of the optical element, the light directly emitted by the LED crystal grain can be guided to a specific direction instead of directly emitting light from the front. In this way, the disadvantage of inability to mix colors caused by the use of a single-color light source in the prior art can be eliminated, and the problem of poor light uniformity must be improved by stacking quite a few layers of components as in the prior art. The effect of color mixing and homogenization of the backlight module can be achieved.

At the same time, the optical element used in the present invention has a simple structure and is easy to manufacture, which can solve the problems in the prior art that are difficult to manufacture, high in cost and unfavorable for industrial utilization due to complex structures and components that must be stacked in multiple layers.

The LED backlight module of the present invention not only achieves color mixing and uniform luminous effects, but also provides an LED backlight module with simple structure and easy manufacture, which can reduce manufacturing costs, increase industrial utilization value, and solve various problems derived from the prior art.

Description of drawings

Fig. 1 is the structural representation of the LED backlight module of embodiment 1 of the present invention;

Fig. 2 is the structural representation of the optical element of embodiment 1 of the present invention;

Fig. 3 is a schematic diagram of the arrangement structure of LEDs according to Embodiment 1 of the present invention; and

FIG. 4 is a schematic structural view of the optical elements in the LED backlight module according to Embodiment 2 of the present invention.

Detailed ways

The following examples further illustrate the viewpoints of the present invention, but do not limit the scope of the present invention in any way.

Example 1

1 to 3 are drawn according to Embodiment 1 of a light emitting diode (Light emitting diode, LED) backlight module of the present invention. As shown in FIG. 1 , the LED backlight module 1 includes a diffusion plate (Diffusion late) 11, a plurality of optical elements 13, a plurality of light emitting diodes 15 and a reflection sheet (Reflection Sheet) 17.

The diffusion plate 11 is arranged under the liquid crystal panel 12 to diffuse the light and perform uniform diffusion. Since the structure and working principle of the liquid crystal panel 12 are all in the prior art, it will not be repeated here.

The optical elements 13 are respectively arranged under the diffusion plate 11, each of the optical elements 13 is preferably a structure made of a material with high light transmittance, wherein the material with high light transmittance can be selected as plastic, glass or other suitable materials . Furthermore, as shown in FIG. 2 , each of the optical elements 13 has a reflective surface 131 with a high reflectivity. Wherein, the reflective surface 131 of each optical element 13 has a metal layer, a dielectric layer or other equivalent film layers such as a mirror surface, and the reflective surface 131 and the LED 15 form an included angle of 1 to 60 degrees. Wherein, the metal layer is a structure that can be formed by evaporation or sputtering, for example, silver or aluminum can be sputtered on the reflective surface 131 of the optical element 13 made of plastic; the dielectric layer can be For the structure formed by stacking multiple layers of dielectric materials, for example, TiO ₂ can be stacked on the reflective surface 131 of the optical element 13 made of glass, for example. The surface of the reflective surface 131 is treated as a mirror surface, and the required material can be changed according to needs, and is not limited to the description in this embodiment.

Each of the light emitting diodes 15 is respectively disposed below each of the optical elements 13 . As shown in FIG. 3 , the light-emitting diodes 15 can be red R, green G, and blue B light-emitting diodes arranged directly under the liquid crystal panel in a staggered arrangement or any arrangement and combination. In this way, each of the light emitting diodes 15 contains an optical element 13 that can control the light distribution curve of the LED. This optical element 13 has a reflective surface 131 with high reflectivity, which can reflect the light directly emitted by the light emitting diode 15 to a specific direction. , rather than emitting light from the front. Of course, those with common knowledge in the technical field know that the light emitting diode 15 can also be a white light emitting diode.

The reflection sheet 17 is arranged under the LED 15 and on the side of the whole module, and reflects the unscattered light from the LED 15 into the liquid crystal panel 12 to increase the efficiency of light use. Since the structures of the diffuser plate 11 and the reflection sheet 17 are well known to those with common knowledge in the technical field, details are not repeated here.

In this embodiment, the LED backlight module 1 may further include a brightness enhancement film (Brightness Enhancement Film, BEF) 19 disposed above the diffusion plate 11, and the brightness enhancement film 19 condenses light to increase luminance. The brightness enhancement film 19 can be, for example, a film or sheet made of Polyester or Polycarbonate, but it is not limited thereto. Meanwhile, in other embodiments, the brightness enhancement film 19 can also be integrated into the liquid crystal panel 12 to reduce cost and simplify the structure. However, this is a change that can be imagined and easily implemented by those with ordinary knowledge in the technical field, so no further explanation will be given.

Since each of the optical elements has a reflective surface 131, the position of the light emitted by each of the light emitting diodes 15 touching the reflective surface 131 is different, so that the high reflectivity characteristics of the light reflected in various directions below can be achieved without direction. Uniform astigmatism effect. Like this, after the light source that this light-emitting diode 15 emits is reflected by this optical element 13, can reflect light into this liquid crystal panel 12 again through this reflector 17, and this diffuser plate 11 then can block the very small number of upward (that is front side) outgoing light Light source to achieve the effect of color mixing and homogenization.

In the prior art, optical elements with special structures are used, and the optical elements must be manufactured using multiple molds, which is costly and difficult to implement. Compared with the prior art, the optical element of the present invention only needs to use, for example, an injection molded substrate, and is easy to process. At the same time, the application of the LED backlight module of the present invention does not need to fully meet the harsh conditions of Total Internal Reflection (TIR), which can solve the problem that the products made in the prior art cannot guide all the light to the side to emit light during actual implementation.

Therefore, the application of the LED backlight module of the present invention can achieve the effect of color mixing and uniformity, not only the manufacturing cost is lower than that of the prior art, but also because it is easy to manufacture and does not have the disadvantages of the prior art, it can increase the industrial utilization value.

Example 2

FIG. 4 is drawn according to Embodiment 2 of the LED backlight module of the present invention. Wherein, the same or similar components as in Embodiment 1 are indicated by the same or similar component symbols, and detailed drawings and descriptions are omitted to make the description of this case clearer and easier to understand.

As shown in Figure 4, the biggest difference between Embodiment 2 and Embodiment 1 is that the optical element 13 in Embodiment 1 has a reflective surface 131 with a V-shaped cross-section, for example, while the optical element 13' in Embodiment 2 provides a It has, for example, a reflective surface 131' with an arc-shaped cross section.

In this embodiment, the design of the reflective surface 131 ′ with an arc-shaped cross-section can further reduce the light scattered from the front and improve the uniformity of light source diffusion.

Certainly, the cross-sectional shape design of the reflective surfaces 131, 131' is not limited to the V-shape and arc shape of the above-mentioned embodiments, and various geometric or non-geometric designs that can facilitate demoulding are applicable to the present invention, such as perfect circle, Oval, sawtooth or other polygons, etc., the curvature value of the reflective surface on both sides of the surface can be determined by the desired light source reflection angle, and the curvature value of the reflective surface on both sides of the surface can be different; in other words, the above-mentioned such as LED The number and setting position of the reflective surface, the shape of the reflective surface, the coating material and the process, etc., can be designed or changed according to actual needs, rather than being limited to the above-mentioned embodiments, and these are all easily accessible to those with ordinary knowledge in the technical field. Thoughtful.

Therefore, the LED backlight module of the present invention can not only control the LED light distribution curve by optical elements, but also guide the light emitted directly from the LED crystal grains to a specific direction, instead of directly emitting light from the front, so as to achieve the effect of color mixing and uniformity. The present invention is simple to manufacture 1. The manufacturing cost is low, the industrial utilization value can be effectively improved, and various shortcomings of the prior art can be solved.

Claims (15)

1. A kind of LED backlight module, is characterized in that, this backlight module comprises: diffusion plate; At least one optical element, disposed below the diffuser plate, has a highly reflective and concave reflective surface; At least one light emitting diode is correspondingly arranged under the optical element, and the emitted light is reflected downward by the reflective surface; and The reflection sheet is arranged under the LED and on the side of the whole module. 2. The LED backlight module according to claim 1, wherein the optical element is a structure made of a material with high light transmittance. 3. The LED backlight module according to claim 2, wherein the material with high light transmittance is one of plastic or glass. 4. The LED backlight module according to claim 1, wherein the reflective surface of the optical element has one of a metal layer and a dielectric layer. 5 . The LED backlight module according to claim 4 , wherein the reflective surface is a reflective surface having a metal layer, and the metal layer is formed by vapor deposition or sputtering. 6 . The LED backlight module according to claim 5 , wherein the metal layer is a structure formed by sputtering silver or aluminum optical elements on plastic. 7. The LED backlight module according to claim 4, wherein the reflective surface is a reflective surface having a dielectric layer, and the dielectric layer is a structure formed by stacking multiple layers of dielectric materials. 8 . The LED backlight module according to claim 7 , wherein the dielectric layer is formed by stacking TiO ₂ on glass to form a reflective surface of an optical element. 9. The LED backlight module as claimed in claim 1, wherein the reflective surface is a geometric cross-section. 10. The LED backlight module according to claim 1, wherein the reflective surface is one selected from the group consisting of V-shaped, arc-shaped, perfect circle, elliptical or zigzag cross-sections. 11. The LED backlight module according to claim 10, wherein the reflective surface is a reflective surface with a V-shaped cross-section, and the angle between the reflective surface with a V-shaped cross-section and the light-emitting diode is between 1 and 60 degrees. angle. 12. The LED backlight module according to claim 1, wherein the backlight module comprises a plurality of relative numbers of optical elements and light emitting diodes. 13. The LED backlight module according to claim 12, wherein the light emitting diodes are any combination of red, green and blue LEDs. 14. The LED backlight module as claimed in claim 1, wherein the LED is a white LED. 15. The LED backlight module according to claim 1, further comprising a brightness enhancement film disposed on the diffusion plate.

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