CN1313874C - LED backlight module - Google Patents

Abstract

An LED backlight module comprises a bottom plate, a plurality of LEDs, a reflector plate, an auxiliary diffusion plate and a diffusion plate. The plurality of LEDs are arranged on the bottom plate. The auxiliary diffusion plate is arranged above the LEDs, the surface of the auxiliary diffusion plate is provided with a plurality of optical microstructures, and the diffusion sheet is arranged above the auxiliary diffusion plate at a preset height. The light generated by the LED can generate total reflection on the auxiliary diffusion plate and the diffusion sheet, and is fully mixed in the LED backlight module, the light leaves the LED backlight module from the upper surface of the diffusion sheet, and the optical microstructure on the surface of the auxiliary diffusion plate is used for guiding the light to the diffusion sheet.

Description

LED backlight module

technical field

The present invention relates to an LED (Light emitting diode) backlight module, in particular to an LED backlight module with an auxiliary diffusion plate, and the auxiliary diffusion plate therein.

Background technique

LED (Light Emitting Diode, Light Emitting Diode) light source will be of great help to liquid crystal display products. The main reason is that the luminous efficiency of LED has been greatly improved. The efficiency, even to the 2005 LED luminous efficiency is expected to keep pace with cold cathode lamps, of course, this is only in terms of the brightness of the LED. If the characteristics of high response speed of LED are applied, red, blue, and green LED light sources can be switched at high speed in sequence, which can not only replace the high unit price color filter in the liquid crystal panel, but also increase the fineness of the liquid crystal display product. and brightness. From this point of view, the impact of LED light sources on the future development trend of liquid crystal display products will be comprehensive and thorough. In addition to being used in liquid crystal display products, once the luminous efficacy of LEDs can be equal to (or exceed) cold cathode lamps, its application level is bound to expand. For example, LED lights have been used in many signal light sources. , such as the traffic lights of traffic signs and the direction lights of cars, etc., if its luminous efficiency improves, the most likely application is to extend it to the lighting source, and the low power consumption and low heat generation characteristics of LEDs, It will bring no small threat to all current lighting sources.

Please refer to FIG. 1 , which is a side sectional view of a known LED backlight module. The LED backlight module 10 includes a frame 12 , a plurality of LEDs 14 , a reflection sheet 16 and a diffusion sheet 18 . The LED backlight module 10 shown in FIG. 1 is because the LED 14 is placed at the bottom, and the upper surface of the diffusion sheet 18 above it is used as the light-emitting surface of the LED backlight module 10, thereby providing light to the liquid crystal panel, so it is usually called direct-down. Type (direct-type) backlight module.

Wherein, a plurality of LEDs 14 are disposed on the bottom plate of the frame 12 as light sources in the LED backlight module 10 . As shown in FIG. 1 , the LED 14 can be divided into a light-emitting area 141 in the upper half and a base 143 in the lower half.

The reflection sheet 16 can reflect the light from the light-emitting area 141 of the LED 14 upwards, so that the light can be fully utilized. The reflective sheet 16 is erected on the frame 12 by utilizing its edge portion, and a plurality of LED holes are arranged therein, so that the light-emitting area 141 of the LED 14 passes through and is located on the reflective sheet 16; the base 143 is below the reflective sheet 16, The base 143 can be used to support the reflection sheet 16 in some known technologies.

The light-transmitting diffuser 18 is also erected on the frame 12 by its edge portion, and due to the difference in refractive index between the material of the diffuser 18 and air, part of the light incident on the diffuser 18 can be totally reflected. As shown in Figure 1, the light is repeatedly reflected or totally reflected between the diffusion sheet 18 and the reflection sheet 16, which can enhance the light mixing effect of the various colors of light emitted by the LED 14, and make the chromaticity and brightness of the light more uniform. Then the LED backlight module 10 is separated from the upper surface of the diffusion sheet 18 .

Generally speaking, the reason why the LED backlight module 10 particularly needs to emphasize the light mixing effect of various colors of light is that individual LEDs 14 can generate light of different colors such as red, green, and blue, but the light provided by the LED backlight module 10 to the liquid crystal panel requires There is uniform chromaticity and brightness, otherwise it will become an unfavorable factor in the imaging of subsequent liquid crystal panels. Therefore, a good light mixing mechanism is required in the LED backlight module 10 so that the light emitted from the LED backlight module 10 has uniform brightness and chromaticity.

It should be noted that since the LED 14 is side emitting, most of the light generated by the LED 14 in the backlight module 10 of FIG. Light, and after multiple reflections (or total reflections) between the reflection sheet 16 and the diffusion sheet 18, when the incident angle of the light incident on the diffusion sheet 18 is greater than the critical angle of total reflection (critical angle), the light will exit the LED backlight Module 10. Please refer to FIG. 2, which shows the range of angles where the LED luminous intensity is strong. The light path (such as arrow a) at an angle of about 80 degrees with the normal line L in FIG. 2 is the position with the strongest luminous brightness of the LED 14, and the main luminous range of the LED 14 is within the angle of plus or minus 20 degrees. It can be seen from the figure that most of the light generated by the LED is indeed emitted toward its side.

According to the description of the above known technologies, it can be known that a good light mixing mechanism is required in the LED backlight module so that the light provided by the LED backlight module has uniform chromaticity and brightness. However, the light mixing mechanism provided by the conventional LED backlight module shown in FIG. 1 still has room for improvement. In addition, when providing a better light mixing mechanism for the LED backlight module, it is still necessary to take into account the side-emitting characteristics of the LED, so as to avoid sacrificing the overall luminous efficiency of the LED backlight module while achieving a good light mixing effect.

The known technology still lacks an LED backlight module capable of taking into account both luminous efficiency and light mixing effect, so as to improve the imperfect light mixing effect in the known technology. And it is expected that the developed new technology will not only significantly improve the light mixing effect, but also be quickly and easily integrated into the existing LED backlight module manufacturing process, so as to benefit the industry's competitiveness in terms of cost and other aspects.

Therefore, for the research and development personnel engaged in the related field of LED backlight module, they must devote themselves to solving the shortcomings still existing in the known technology, in order to further improve the quality of LED backlight module products.

Contents of the invention

The main technical problem to be solved by the present invention is to provide an LED backlight module that can take both luminous efficiency and light mixing effect into consideration.

Another technical problem to be solved by the present invention is to provide an LED backlight module that can be quickly and easily integrated into the existing LED backlight module manufacturing process.

For this reason, the technical solution of the present invention is: an LED backlight module, including a base plate; a plurality of LEDs, arranged on the base plate; an optical microstructure; and a diffusion sheet, which is arranged above the auxiliary diffusion plate at a predetermined height, and the LED backlight module uses the upper surface of the diffusion sheet as a light-emitting surface.

The characteristics and advantages of the present invention are: the LED backlight module provided by the present invention includes a bottom plate, a plurality of LEDs, a reflection sheet, a diffusion sheet and an auxiliary diffusion sheet. The bottom plate is part of the frame of the LED backlight module. The frame can carry the LEDs in the LED backlight module, the reflection sheet, the diffusion sheet and the auxiliary diffusion sheet.

A plurality of LEDs are arranged on the bottom plate of the frame, and each LED includes a light-emitting area and a base. Individual LEDs can produce red, green, and blue colors.

The reflector is erected on the frame, which has a plurality of LED holes, and can fit on the outside of the LED, so that the light-emitting area of the LED is located on the reflector, and the base of the LED is located under the reflector and carries the reflector.

The auxiliary diffusion plate is erected on the frame and arranged above the LEDs; the surface of the auxiliary diffusion plate has a plurality of optical microstructures. The diffusion sheet is erected on the frame and arranged above the auxiliary diffusion plate at a predetermined height, and the LED backlight module uses the upper surface of the diffusion sheet as a light-emitting surface.

Wherein, the diffusion sheet and the auxiliary diffusion plate can transmit light. Due to the fact that the refractive index of the material of the diffuser and the auxiliary diffuser is different from that of air, the light generated by the LED can be totally reflected on the surface of the auxiliary diffuser and the diffuser, and reflected on the surface of the reflector. However, the light is fully mixed in the LED backlight module, and leaves the LED backlight module through the above-mentioned light emitting surface. The optical microstructure on the surface of the auxiliary diffusion plate is used to guide the light inside the LED backlight module to the diffusion plate above it and the above-mentioned light-emitting surface.

The invention provides an LED backlight module that takes both luminous efficiency and light mixing effect into consideration. The present invention not only provides an LED backlight module with a diffusion sheet and an auxiliary diffusion plate, but also has a good light mixing effect, and improves the luminous efficiency of the LED backlight module in the known technology by improving the auxiliary diffusion plate Indistinct shortcomings. Moreover, the new technology developed by the present invention has excellent manufacturing convenience, and can be quickly and easily integrated into the existing LED backlight module manufacturing process. At the same time, the auxiliary diffuser plate of the present invention further improves the luminance of the LED backlight module. In this way, the present invention not only meets the considerations of the industry on cost and manufacturing, but also has great progress, and is beneficial to enhance the competitiveness of the industry.

Description of drawings

Fig. 1 is a side sectional view of a known LED backlight module;

Figure 2 shows the angle range where the LED luminous intensity is strong;

Fig. 3 is a side sectional view of the LED backlight module of the present invention;

Fig. 4 is a side sectional view of another embodiment of the present invention;

Figure 5 is a side sectional view of another embodiment of the present invention; and

FIG. 6 shows a perspective view of the auxiliary diffuser plate in FIG. 5 .

Explanation of reference numbers:

10, 20, 40, 50, 60, LED backlight module 12, 42, frame

14, 44, LED 141, 441, luminous area 143, 443, base

16, 46, reflector 18, 48, diffuser 421, bottom plate

461. LED hole 52. Auxiliary diffusion plate a, a’, arrow

521, 521a, 521b, optical microstructure L, normal line 523, specular reflection sheet

Detailed ways

With the following detailed description combined with the accompanying drawings, the above contents and many advantages of the present invention can be easily understood.

Please refer to FIG. 3 . FIG. 3 is a side sectional view of the LED backlight module of the present invention. The LED backlight module 40 includes a frame 42 including a bottom plate 421 , a plurality of LEDs 44 , a reflector 46 , a diffuser 48 and an auxiliary diffuser 52 .

The bottom plate 421 is a part of the frame 42 of the LED backlight module 40 , and it can be made of metal materials (such as aluminum, magnesium) or PC materials. The frame 42 can carry the LED 44 in the LED backlight module 40 , the reflection sheet 46 , the diffusion sheet 48 and the auxiliary diffusion plate 52 .

A plurality of LEDs 44 are disposed on the bottom plate 421 , and each LED 44 includes a light emitting area 441 and a base 443 . A single LED44 can produce three colors of red, green and blue light.

The reflective sheet 46 is erected on the frame 42 and has a plurality of LED holes 461, which can fit on the outside of the LED 44, so that the light-emitting area 441 of the LED 44 is located on the reflective sheet 46, and the base 443 of the LED 44 is located under the reflective sheet 46. And carry the reflection sheet 46 .

It is worth noting that the auxiliary diffuser plate 52 provided by the present invention is set above the reflection sheet 46 , which is erected on the frame 42 and placed above the LEDs 44 ; the surface of the auxiliary diffuser plate 52 has a plurality of optical microstructures 521 . As shown in FIG. 3 , in an embodiment of the present invention, the optical microstructure 521 is formed on the upper surface of the auxiliary diffuser plate 52 .

The diffuser 48 is erected on the frame 42 and disposed above the auxiliary diffuser 52 at a predetermined height. The LED backlight module 40 uses the upper surface of the diffuser 48 as a light emitting surface. In an embodiment of the present invention, the aforementioned predetermined height is between 25mm˜35mm, and the thickness of the auxiliary diffuser plate 52 is about 1cm.

According to the LED backlight module 40 of the present invention shown in FIG. 3 , the diffuser 48 and the auxiliary diffuser 52 can transmit light. As a result of the refractive index of the material of the diffuser 48 and the auxiliary diffuser 52 being different from the refractive index of air, the light generated by the LED 44 can be generated by total reflection on the surface of the auxiliary diffuser 52 and the diffuser 48, and in the air. The reflection produced on the surface of the reflective sheet 46 fully mixes the light in the LED backlight module 40 , and leaves the LED backlight module 40 through the above-mentioned light output surface (the upper surface of the diffusion sheet 48 ). Wherein the optical microstructure 521 on the surface of the auxiliary diffusion plate 52 is used to make the light inside the LED backlight module 40 easy to emit light and be directed to the diffusion sheet 48 above it and the above-mentioned light emitting surface, as shown in FIG. 3 , the light (such as Arrow a) The optical microstructure 521 on the upper surface of the auxiliary diffuser plate 52 can change its light path, and irradiate to the upper diffuser 48 (such as arrow a′).

In practice, a layer of reflective film (not shown) can be laid on the side wall of the frame 42 and the upper surface of the reflective sheet 46, such as the E60L silver reflective film produced by Toray Company, to reduce the reflection of light during multiple reflections. resulting losses.

In addition, further considering the overall optical uniformity of the LED backlight module 40, an enhanced specular reflector (ESR dot, enhanced specular reflector) 523 can be formed on the lower surface of the auxiliary diffuser plate 52 and corresponding to the position directly above each LED 44 , so as to prevent the light emitted directly upward by the LED 44 from destroying the overall optical uniformity of the LED backlight module 40 .

In the known LED backlight module, there is a dilemma that the luminous efficiency and light mixing effect cannot be balanced. However, for liquid crystal display products that emphasize light chromaticity and brightness uniformity, it is desirable to use an LED backlight module as shown in Figure 2 , to meet the needs of sufficient light mixing.

Therefore, the LED backlight module 40 provided by the present invention has an auxiliary diffuser plate 52, and the optical microstructure 521 on the surface of the auxiliary diffuser plate 52 can increase the surface area of the auxiliary diffuser plate 52 and increase the chance of light output; Forming the optical microstructure 521 on the upper surface of the plate 52 instead of a flat surface will cause the incident angle of the light on the upper surface of the auxiliary diffuser plate 52 to be different from that of the flat surface, which is less likely to produce total reflection and is easy to The light is emitted, thereby guiding the light inside the LED backlight module 40 to the diffusion sheet 48 above it.

One of the reasons for the poor luminous efficiency of the known LED backlight module is that the LED belongs to side emitting (side emitting), and most of the light generated by it will not be directly emitted to the light-emitting surface above, and as shown in Figure 2, the LED The main lighting angle is between 80 degrees and the normal line L, and within the range of plus or minus 20 degrees.

Therefore, the optical microstructure 521 on the surface of the auxiliary diffuser plate 52 of the present invention can contribute to the light emitted from the side of the LED 44 and part of the back and forth reflection (or total reflection) between the auxiliary diffuser plate 52 and the reflector 46. The light corrects its optical path and is directed to the diffuser 48 . In this way, the auxiliary diffuser plate 52 can improve the overall uniformity of chromaticity and brightness without reducing the luminous efficiency of the LED backlight module.

In practice, the material of the auxiliary diffuser plate 52 can be selected from acrylic material (PMMA), polycarbonate material (PC material) or cycloolefin polymer material (COPs, Zeonor), and the formation of the optical microstructure 521 The structure corresponding to the optical microstructure 521 can be provided in advance on the mold for making the auxiliary diffuser plate 52 , so that the optical microstructure 521 can be integrally molded during the injection molding process of the auxiliary diffuser plate 52 .

In another embodiment, the optical microstructure 521 can be a V-cut structure, and the V-cut scraper can be used to make a smooth surface on the original flat acrylic material (PMMA), polycarbonate material (PC material) or cycloolefin polymer material. (COPs, Zeonor) form the required optical microstructure 521 to produce the auxiliary diffuser plate 52 of the present invention. In this way, the auxiliary diffuser plate provided by the present invention has excellent convenience in manufacture.

Taking the optical microstructure 521 of the V-cut structure as an example, as shown in Figure 3, a plurality of V-cut structures (optical microstructures 521) arranged in parallel can guide light to the diffuser 48 above, because of its structure It is similar to a prism, so it can have the effect of collecting light; and because the individual V-cut structures are very small, and the distribution of each V-cut is quite uniform, the light collecting effect will not cause uneven brightness of the LED backlight module 40 , and contribute to the improvement of the overall brightness.

It is worth mentioning that the design and distribution density of the V-cut structure must take into account the actual light emission of the backlight, and can be used to fill dark areas and increase the overall brightness. According to an embodiment of the present invention, the distance between two adjacent V-cuts in the V-cut structure can be between 1-300 μm; and, depending on whether there is a dark area on the light-emitting surface of the actual LED backlight module 40, the dark area can be reduced. The distance between the V-cut structures corresponding to the area positions is set to be shorter (the density of the V-cut structures is higher) to increase the brightness of the dark area, thereby improving the uneven light output caused by the dark area. The height of individual V-cut structures can be tens of μm.

In addition to the above considerations in implementing the present invention, when the LED backlight module 40 of the present invention is applied to liquid crystal display products, various known optical films can be used on the diffuser 48 to improve the overall optical performance, such as the above , Lower prism sheet, upper and lower diffusion sheet...etc.

Please refer to FIG. 4 , which is a side sectional view of another embodiment of the present invention. In addition to the embodiment shown in FIG. 3 , the optical microstructure 521 in the present invention can also be disposed on the lower surface of the auxiliary diffuser plate 52 as shown in FIG. 4 . In terms of the quality of light provided, the difference between the LED backlight module 50 in FIG. 4 and the LED backlight module 40 in FIG. 3 is not far away.

FIG. 5 shows a side sectional view of another embodiment of the present invention. In the LED backlight module 60 , the optical microstructure 521 a is disposed on the upper surface of the auxiliary diffuser plate 52 , and the optical microstructure 521 b is disposed on the lower surface of the auxiliary diffuser plate 52 .

FIG. 6 shows a perspective view of the auxiliary diffuser plate 52 in FIG. 5 , wherein the optical microstructures 521 a and the optical microstructures 521 b are arranged perpendicular to each other. Taking the V-cut structure as an example, V-cut scrapers can be used to form V-cut structures on the upper and lower surfaces of the auxiliary diffuser plate 52 in directions perpendicular to each other, so as to realize the auxiliary diffuser plate 52 shown in FIG. 6 . The advantage of this implementation is that the light collection effect of the LED backlight module caused by the optical microstructure will not only be evenly distributed in the form of fine parallel lines, but also be evenly distributed in the form of dots arranged in arrays.

Based on the above, the present invention provides an LED backlight module that can take into account both luminous efficiency and light mixing effect. effect, and through the optical microstructure of the auxiliary diffuser plate, it avoids sacrificing the luminous efficiency of the LED backlight module while improving the light mixing effect. Moreover, the new technology developed by the present invention has excellent manufacturing convenience, and can be quickly and easily integrated into the existing LED backlight module manufacturing process. At the same time, the auxiliary diffusion plate of the present invention further improves the luminance of the LED backlight module, and the optical microstructure in it can adjust the distribution density to improve the dark area of the light emitting surface of the LED backlight module and improve the uniformity of light output.

Although the present invention has been disclosed with specific embodiments, it is not intended to limit the present invention. Any person skilled in the art can make replacements of equivalent components without departing from the concept and scope of the present invention, or replace them according to the present invention. The equivalent changes and modifications made in the scope of patent protection shall still fall within the scope of this patent.

Claims (10)

1. a LED-backlit module is characterized in that, described LED-backlit module comprises:

One base plate;

A plurality of LED are arranged on this base plate;

One auxiliary diffuser plate is arranged at above-mentioned LED top, and this auxiliary diffuser plate surface has a plurality of optical microstructures; And

One diffusion sheet is arranged at this auxiliary diffuser plate top with a predetermined altitude, this LED-backlit module is an exiting surface with the upper surface of this diffusion sheet.

2. LED-backlit module as claimed in claim 1 is characterized in that, this auxiliary diffuser plate and this diffusion sheet this predetermined altitude apart is between 25mm～35mm.

3. LED-backlit module as claimed in claim 1 is characterized in that, described optical microstructures is formed at this auxiliary diffuser plate upper surface.

4. LED-backlit module as claimed in claim 1 is characterized in that, described optical microstructures is formed at this auxiliary diffuser plate lower surface.

5. LED-backlit module as claimed in claim 1 is characterized in that, described optical microstructures is formed at this auxiliary diffuser plate upper surface and lower surface.

6. LED-backlit module as claimed in claim 1 is characterized in that, described optical microstructures is the V-cut structure.

7. LED-backlit module as claimed in claim 5 is characterized in that, the described optical microstructures of this auxiliary diffuser plate upper surface is perpendicular to the described optical microstructures of this auxiliary diffuser plate lower surface.

8. LED-backlit module as claimed in claim 1 is characterized in that, the material of this auxiliary diffuser plate is selected from acryl material, polycarbonate material or cyclic olefin polymerization material.

9. LED-backlit module as claimed in claim 1, it is characterized in that, the light that described LED produced is by producing total reflection between this optical microstructures and this diffusion sheet surface, and in this LED-backlit module mixed light fully, and leave this LED-backlit module by this exiting surface.

10. LED-backlit module as claimed in claim 1, it is characterized in that, described LED-backlit module also has reflector plate, this reflector plate is erected on the framework, and LED hole with a plurality of LED of being sleeved on outside, so that the luminous zone of LED is positioned on this reflector plate, and the base of LED is positioned under the reflector plate, and the carrying reflector plate.

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