CN201246632Y - Large area uniform luminance LED backlight device - Google Patents

Abstract

A large-area uniform brightness LED backlight device, which solves the technical problem of how to use as few LEDs as possible to obtain higher brightness and better light color uniformity for large-scale LED backlight sources. The technical solution adopted is that the backlight device , including: a shell and an LED light source, the inner surface of the shell wall is provided with a reflective film, the LED light source is set on the bottom of the shell through an aluminum substrate, and an array of reflective circles composed of reflective circles is arranged sequentially above the LED light source. The circular spots are arranged on the light-transmitting plate, the diffusion film, the brightness enhancement film, the bottom of the casing and the reflective circular spot array form the bottom light mixing space, the reflective circular spot array and the diffusion film form the upper light mixing space, and the reflective circular spots The number of settings is the same as that of the LED light source, the diameter of the reflection circle is larger than the diameter of the LED light source, and the setting position of the reflection circle is in the normal light emitting direction of the LED light source. The advantage is that it has high brightness and high light color distribution uniformity without increasing the number of LEDs.

Description

Large-area uniform brightness LED backlight device

technical field

The utility model relates to a large-area LED backlight device, in particular to a light source using a high-power light-emitting diode (LED). Backlight can also be used as a surface light source for large-area uniform brightness LED backlight devices used in high-quality advertisements and art designs.

Background technique

Liquid crystal displays are becoming one of the mainstreams of optoelectronic display products such as flat-panel TVs, computer display screens, and desktop monitors, and are recognized and loved by mass consumption. The combination of high-quality graphic art advertisements and light source technology brings people high-quality visual enjoyment. These are closely related to the light source. Especially for thin film transistor array liquid crystal display (TFT-LCD), high-quality backlight system (backlight module) has become an important part of TFT-LCD and has attracted more and more attention from engineers and technicians. Since TFT-LCD is a passive light-emitting display device, the light must be projected through the backlight, and then penetrate the polarizer, glass substrate, liquid crystal layer, color filter, glass substrate, polarizer and other related components in the TFT-LCD panel. , and finally enter the human eye for imaging to realize the display function. Therefore, the performance of the backlight module directly affects the quality of TFT-LCD imaging.

At present, the backlight source of TFT-LCD display is mainly based on cold cathode fluorescent lamp (CCFL). Although CCFL has advantages in price and brightness, it has disadvantages such as poor color rendering, mercury, and glass products, and its application is being limited. High-power light-emitting diodes (LEDs) have become a research and development hotspot in LCD backlight modules due to their high color rendering index, energy saving, environmental friendliness, and durability. Small and medium power LEDs are used as backlight sources, mainly for small-sized portable LCD display products, such as mobile phones, personal digital assistants, etc. High-power LEDs are mainly used in large-size display devices such as televisions, and have not yet been widely used. The main reason is that there are technical bottlenecks, such as heat dissipation, light efficiency, and large-area light color uniformity, especially the latter, which currently has no particularly good solution. Although increasing the number of LEDs can increase brightness and enhance uniformity, the cost of high-power LEDs is bound to increase the cost of the backlight module. Secondly, due to the increase in the number of LEDs and the increase in external supply current, the heat generated by the module rises sharply, causing the temperature of the system to rise sharply. Performance indicators such as efficacy and life of LEDs deteriorate with the increase of temperature, resulting in a decrease in brightness and a drift in chromaticity. As a result, the brightness of the light-emitting surface of the backlight is reduced, and the uniformity of brightness and chromaticity is deteriorated. The LCD display is distorted and the viewing effect is deteriorated. Therefore, the key issue of large-size LED backlight is how to use as few LEDs as possible to obtain higher brightness and better light color uniformity, that is, to obtain the maximum light color uniformity and meet the requirements with the minimum electric power. brightness.

Contents of the invention

In order to solve the technical problem of how to use as few LEDs as possible to obtain higher brightness and better light color uniformity for large-size LED backlight sources, that is, to obtain the maximum light color uniformity and brightness that meets the requirements with the minimum electric power , The utility model provides a large-size LED backlight device, which solves the technical deficiencies in the prior art.

The design idea adopted by the utility model to realize the purpose of the invention is to use high-power white light LED as light source, adopt the direct-down backlight design, design a reflection spot above each LED, and place the LED near the central axis direction (that is, the 0° angle of the LED) The light emitted by the LED is reflected back to the bottom where the LED is located. Add a layer of reflective film at the bottom to reflect the light reflected to the bottom and then go out. The advantages of doing so are: one is to enhance the uniformity of light output, and the other is to make full use of the light generated by each LED, so that the uniformity of light color can be effectively enhanced without increasing the electric power.

The specific technical solution adopted by the utility model to realize the purpose of the invention is a large-area uniform brightness LED backlight device, including: a housing and an LED light source arranged in the housing, the inner surface of the housing wall of the housing is provided with a reflective film, and the LED light source is passed through an aluminum The substrate is set at the bottom of the shell, and above the LED light source, a reflective circle array composed of reflective circles is set in turn. The light mixing space is formed between the arrays, and the light mixing space is formed between the reflective circular spot array and the diffusion film. The number of reflective circular spots is the same as that of the LED light source. The diameter of the reflective circular spot is larger than the diameter of the LED light source. The setting of the reflective circular spot The position corresponds to the light emitted by the LED light source normal.

The beneficial effect of the utility model is that compared with the existing design scheme, the utility model has high brightness and high light color distribution uniformity under the premise of not increasing the number of LEDs.

Description of drawings

Accompanying drawing 1 is the structural representation of the utility model.

Accompanying drawing 2 is the schematic diagram of LED light source array arrangement.

Figure 3 is a schematic diagram of the distribution of the reflective circular spot array.

In the accompanying drawings, 1-1 shell, 1-2 reflective film, 1-3 aluminum substrate, 1-4 LED light source, 3-1 light-transmitting part, 3-2 reflective circular spot, 1-5 light mixing space at the bottom, 1- 6 brightness enhancement film, 1-7 diffusion film, 1-8 reflective circular spot array composed of 1-8 reflective circular spots, 1-9 transparent plate, 1-10 upper light mixing space.

Detailed ways

Referring to accompanying drawing 1, a LED backlight device with large area and uniform brightness, the inner surface of the shell wall of the shell 1-1 is provided with a reflective film 1-2, and the LED light source 1-4 is arranged on the shell 1-1 via an aluminum substrate 1-3. At the bottom, above the LED light source 1-4, a reflective circular spot array 1-8 composed of reflective circular spots 3-2 is sequentially arranged. The reflective circular spots 3-2 are arranged on the light-transmitting plate 1-9, and the diffusion film 1- 7. The brightness enhancement film 1-6, the light mixing space 1-5 is formed between the bottom of the shell 1-1 and the reflective circle spot array 1-8, and the light mixing space 1-5 is formed between the reflective circle spot array 1-8 and the diffusion film 1-7. In light space 1-10, the number of reflection circles 3-2 is the same as that of LED light source 1-4, the diameter of reflection circle 3-2 is larger than that of LED light source 1-4, and the setting position of reflection circle 3-2 The light emitted by the LED light source 1-4 corresponds to the normal.

The principle of the device to achieve uniform distribution of brightness is as follows: the light emitted by the LED light source 1-4 is the strongest in the normal direction, and it is irradiated on the diffusion film 1-7 to form a circular spot array 1-8 corresponding to the LED light source 1-4. Produces regular uneven brightness distribution. A reflective circular spot 3-2 is placed in the normal direction of the LED light source 1-4 to reflect the light in the normal direction to the bottom of the housing 1-1, and then reflected back to the color mixing space 1-5 through the bottom reflective film. In this way, after multiple reflections, the light is fully mixed, projected onto the diffusion film 1-7, and then expands laterally through the diffusion film 1-7 to form a uniform brightness distribution. Afterwards, through further color mixing in the color mixing space 1-10 between the diffusion film 1-7 and the brightness enhancement film 1-6, better uniform brightness distribution is achieved. Finally, it is emitted from the front through the brightness enhancement film to form a flat light source with good brightness and uniformity. Since the device changes the direction of the excessively strong direct light in the normal direction so that it is emitted from other directions, the light in the weaker outgoing direction is compensated. The device uses passive reflection elements to change the light intensity distribution of the LED light sources 1-4, fully utilizes the light output of the LED light sources 1-4, and realizes high brightness and uniform distribution of brightness without increasing external energy supply.

In the embodiment of the present utility model, the reflective circular spot 3-2 may be a specular reflection or a diffuse reflective surface reflective circular spot. The specular reflection circle spot 3-2 is a vacuum coating reflection circle spot on the light-transmitting plate 1-9 or a specular reflection sheet pasted on the light-transmitting plate 1-9. A reflective circular spot array 1-8 is set above the LED light source 1-4, and the reflective circular spot array 1-8 is a specular reflective type, and a circular spot array pattern formed by an emissive material is directly produced on the glass transparent plate 1-9 , For example, aluminum is deposited on the transparent glass plate 1-9 by a vacuum coating process to form an array of small round mirrors.

According to the above principle, the second embodiment provided by the utility model is that the circular spot reflection array is diffuse reflection type, and the diffuse reflection material is directly sprayed on the glass transparent plates 1-9 by spraying process. The light emitted by the LED light source 1-4 along the normal direction is diffusely reflected on the reflective film 1-2 on the bottom surface of the housing 1-1, and is output by the diffuser plate after being fully mixed in the color mixing space 1-5.

Mirror reflection type

The basic structure of the specular reflective reflective circle spot array 1-8 and the LED light source 1-4 is shown in Figure 1. 4. Bottom light mixing space 1-5, output brightness enhancement film (1-6), diffusion film (1-7), reflective spot array 1-8, transparent plate 1-9, upper light mixing space 1-10, etc. . The shell 1-1 is made of aluminum alloy plate, which is good for heat dissipation. Both the side wall and the bottom plate have reflective films 1-2 to reflect the light falling on them to the upper light mixing space 1-5 and the lower mixing space 1-10. Our experimental results show that the reflective film 1-2 on the surface of the inner wall can increase the brightness of the light-emitting surface by more than 60%. More importantly, the reflective film 1-2 changes the uniformity of the light-emitting surface, especially the uniformity of the edge sex. The function of the LED aluminum substrate 1-3 is to assist the LED light source 1-4 to dissipate heat, and there are currently commercially available products available for use. The LED light source is the core of the backlight, and a high-power LED light source is selected here, and its power ranges from 0.5W to 3W. Usually choose 1W LED light source. The LED light source forms good thermal contact with the aluminum substrate 1-3, and the heat accompanying the light emission of the LED light source 1-4 is discharged through the aluminum substrate. This is very important. If the heat generated by light sources 1-4 cannot be discharged in time, the luminous efficacy of LED light sources will seriously deteriorate. At present, there are commercially available products that seal LEDs and aluminum substrates together. The bottom and upper light mixing spaces realize the full mixing of light, so that the light in any direction is not more prominent than the light in other directions. The size of the light mixing space can be set according to the needs, and our results show that the space in the range of 10-30mm is more suitable. The output brightness enhancement film is actually the output surface of the backlight device, and its function is to enhance the brightness of the output light. A commercially available product can be used as it is. The role of the diffusion film is to enhance the lateral expansion of light, enhance the point spread function of light, and make the light diffuse in it to achieve the purpose of uniform light intensity distribution. The most important light-transmitting plate 1-9 in the utility model is made up of reflection circular spot 3-2 and light-transmitting part 3-1. The reflective spot 3-2 is located directly above the LED light source 1-4, and reflects the light emitted by the LED light source 1-4 along the normal direction back to the bottom reflective film 1-2, making the peak distribution in the normal direction more flat . The light in the normal direction shows greater randomness in the direction after multiple reflections, which not only improves the utilization rate of light, but also ensures the uniformity of light. For the specular reflective circular spot arrays 1-8, there are many ways to physically realize them. For example, the reflective film is made into a suitable size and glued to the optical glass plate according to the arrangement of the LED light sources 1-4, or a vacuum process can be used to directly form a reflective circular spot on the glass light-transmitting plate 1-9.

Diffuse type

The diffuse reflective structure provided by the utility model is basically the same as the specular reflective structure in Example 1, the difference is that the reflective circular spot arrays 1-8 here are diffuse reflective. Referring to Figure 3, by selecting appropriate materials, diffuse reflection circular spots 3-2 can be formed by using silk screen technology and spraying technology to form a diffuse reflection circular spot array 1-8, which can be installed in a suitable position in the backlight device. To achieve the purpose of uniform output light.

Claims (4)

1, a kind of large tracts of land uniform luminance LED-backlit device comprises: shell and setting led light source in the enclosure is characterized in that; The shell wall inner surface of described shell (1-1) is provided with reflectance coating (1-2), led light source (1-4) is arranged on the bottom of shell (1-1) through aluminium base (1-3), be disposed with the reflection circle spot array of forming by reflection circle spot (3-2) (1-8) in the top of led light source (1-4), reflection circle spot (3-2) is arranged on the light-passing board (1-9), diffusion barrier (1-7), brightness enhancement film (1-6), constitute mixed light space (1-5), bottom between the bottom of shell (1-1) and the reflection circle spot array (1-8), constitute mixed light space, top (1-10) between reflection circle spot array (1-8) and the diffusion barrier (1-7), that quantity is set is identical for be provided with quantity and the led light source (1-4) of reflection circle spot (3-2), the diameter of reflection circle spot (3-2) is greater than led light source (1-4) diameter, reflection circle spot (3-2) the position is set in led light source (1-4) normal light direction correspondence.

2, a kind of large tracts of land uniform luminance LED-backlit device according to claim 1 is characterized in that: described reflection circle spot (3-2) is minute surface reflection or diffuse surface reflection circle spot.

3, a kind of large tracts of land uniform luminance LED-backlit device according to claim 2 is characterized in that: described minute surface reflection circle spot (3-2) is for the vacuum coating reflection circle spot on light-passing board (1-9) or for sticking on the minute surface reflecting piece on the light-passing board (1-9).

4, according to claim 2 or 3 described a kind of large tracts of land uniform luminance LED-backlit devices, it is characterized in that: described diffuse reflection circle spot (3-2) is serigraphy on light-passing board (1-9) or spraying diffuse reflection mating plate.

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