LED panel light knowledge how to buy a cost-effective panel light

First, the LED panel light overview

LED panel light is a new type of surface light source similar to LCD TV backlight technology. It is a high-grade indoor lighting fixture. Its outer frame is made of aluminum alloy by anodizing. The light source is LED. The whole lamp design is beautiful and simple. The atmosphere is luxurious, and it has good lighting effects and can bring people a beautiful feeling. The panel lamp has a unique design, and the light passes through the light transmittance plate with high light transmittance to form a uniform planar light-emitting effect, and the illumination uniformity is good, the light is soft, comfortable and bright, and the eye fatigue can be effectively alleviated.

From the perspective of green lighting design, panel light materials are environmentally friendly, low power consumption, luminous efficiency, lighting brightness and other aspects are better than grille lights, real daylights, night lighting. It is gradually replacing the grille lamp with T8 fluorescent lamps as the light source. Due to the low utilization rate of the traditional grille lamp, it is only about 65%, and the utilization rate of the flat lamp is as high as 90%.

Second, the LED panel light components

Main components of the panel light

1 frame: mainly for heat dissipation, generally aluminum profiles

2 diffuser: shields debris and makes the light more uniform

3 light guide plate: change the trajectory of light to make it evenly arranged

4 reflective film: the light from the light guide plate is emitted from the front

5 bottom plate: auxiliary heat dissipation, shielding foreign objects from intrusion

6PCBA: LED light board, the light source of the panel light

7 power supply: drive the panel light to light

The following focuses on the aluminum frame of the light guide plate diffuser

1. Introduction of light guide plate

Light guide plate process: there are silk screen, laser dot, V-groove,

Light guide plate thickness: There are many kinds of thicknesses for panel lights. 3mm, 4mm, 6mm, 8mm, different thicknesses, different types, different prices of plates are also different. Personally, the light guide plate is mainly light guiding effect. As long as the light guiding efficiency is high, the uniform illuminance is high, and the phenomenon of yellowing and blistering does not occur for a long time of lighting, and the others are floating clouds. At present, the light-guided light guide plate has the highest light guiding efficiency and the best effect, but the price is also the most expensive in these categories! - The price difference varies from 5-15 yuan. The thicker the thickness of the sheet, the higher the illuminance. Now there are more 4mm light guide plates on the market, because the price of 4mm and 6mm plates is about 20-30 yuan. Therefore, on the light guide plate, you must know the type of panel light guide plate you need and the thickness of the plate material manufacturer and thickness. The light guide plate is relatively high in this piece of water, and the price of the poor light guide plate is about 30 yuan!

Principle of illumination: the basic principle of backlighting.

The backlight we are referring to is mainly a side-lit backlight. The principle is to add a protrusion or a pit at the bottom of the light guide plate, or even a white brushing point, to change the direction of light propagation to achieve the effect of emitting light from the front. In the design of the backlight, a major goal and challenge is to ensure the efficiency of light utilization in the direction of vertical light propagation, as shown in Figure 1 below.

Figure 1 Schematic diagram of light transmission

When the incident light is in the conduction process of the light guide plate, if the astigmatism point is encountered, the diffuse reflection light of each angle is formed, and the propagation of the light energy varies with the length of the light guide plate, so that the uniformity of the emitted light and the efficiency of the light output are ensured. It will increase with the length of the light guide plate, as shown in Figure 2 below. The intensity of the diffuse light is proportional to the intensity of the incident light at that location and is proportional to the area of the scattering point. Therefore, during the incident light propagation, the intensity of the incident light is gradually weakened due to the diffuse reflection. Therefore, in order to ensure uniform light emission on both sides of the light guide plate, the diameter of the scattering point near the end of the light source is smaller, and the diameter at the other end is smaller. To be bigger, as shown in Figure 3.

Figure 2 design goal: uniformity

Figure 3 Schematic diagram of the light guide plate

There are many ways to change the light extraction efficiency: you can change the density of the light spot on the light guide, the size of the dot, and the spacing of the dots. The specific dot distribution on the bottom surface of the light guide plate is related to the actual light distribution curve of the LED, and is also related to the specific size of the backlight panel. The key to the design is to find a reasonable dot distribution to obtain a uniform brightness distribution.

According to the above method, the optical software can be used for modeling, and different dot parameters can be set. The dot parameters can be two-dimensional or three-dimensional dots with different size or density. In order to provide the best uniformity, the density change of the dots can be displayed. To avoid the occurrence of moiré, the density of dots in each area is different. Then Monte Carlo random ray tracing method is used to calculate and simulate the luminosity, and the tracking results are analyzed to determine the number of cells dividing the light guide plate. Then, by analyzing the output illuminance distribution pattern, it is repeatedly adjusted repeatedly. The dot parameters are optimized for the ultimate brightness and uniformity.

The structure of the backlight module is shown in the following figure:

2. Diffusion board introduction:

From the material, the PS PMMA PC PP composite can be divided into common plates. The special light dispersing agent is added to the plate. Under the premise of ensuring high light transmittance, the incident angle of the incident light is changed to make the light reach the effective light emitting surface. Refraction and scattering occur at the time to obtain a good light diffusion effect. This material is characterized by a high light transmittance that allows light to pass through the sheet as much as possible, reaches the effective light-emitting surface, avoids being reflected and absorbed, and forms a white, hazy, turbid appearance on the effective light-emitting surface, thereby improving light efficiency and reducing Energy consumption.

At present, the panel lights are mostly made of PS materials, and a small amount of other materials are used. The price of PC is relatively expensive. It is PMMA, then PS, and then PP. The price difference here also ranges from 5-20 yuan.

3. Introduction of frame profiles: The frame materials are generally 6063 or 6061, the price difference is small, mainly depends on the cross-sectional area of the designed frame, the cross-section is small, the material reduction price is relatively low, and the price difference of the frame is generally also 1 -3 yuan. Followed by the rear cover, the thickness of the rear cover is not the same, the commonly used is generally 0.6 0.8 thickness and 1.0 thickness, and now there is also the use of iron bottom plate, the price difference is up to a dozen dollars or so

Third, the panel light scheme comparison:

For the LED light-in mode and the thickness of the light guide plate, the LED interval was simulated and optimized by LightTools optical design software.

Scheme (1) When the total luminous flux of the light source is the same, the light is incident from one side, two sides, and four sides, respectively. The thickness of the light guide plate is 4 mm; the interval between the LEDs is 10 mm; the end face on the light entrance side is a smooth vertical cut surface, and the reflective strip on the non-light entrance side.

From the comparison of the parameters of three different light-in methods, the efficiency of unilateral light input is the highest, and the uniformity of light entering the four sides is the highest.

Scheme (2) The thickness of the light guide plate is different: 3mm, 4mm, 5mm. The LED enters the light from both sides; the LED spacing is 10mm; the light-incident end surface is a smooth vertical section, and the non-light-inside side reflective strip

From the simulation results of three different thicknesses of light guide plates, the uniformity of the light guide plate with a thickness of 4 mm is the best, and the light guide plate with a thickness of 3 mm is the second. In terms of efficiency, the 3mm light guide plate is the most efficient, and the 4mm light guide plate is the second.

Scheme (3) LED spacing is different: 5mm, 10mm, 15mm. The light source enters the light from both sides; the thickness of the light guide plate is 4 mm; the end face on the light entrance side is a smooth vertical cut surface, and the non-light-inside side reflective strip

In the first scheme, there are three different ways of entering light, one side, two sides and four sides. From the comparison of the parameters of three different light-in methods, the efficiency of one-side light input is the highest, and the uniformity of light entering the four sides is the highest, and the light entering the two sides is average in terms of uniformity and efficiency.

The common point of scheme 2 and scheme 3 is that the LEDs are all double-sided. The difference lies in the thickness of the light guide plate and the arrangement interval of the LEDs. From the comparison of the simulation results of the second scheme and the third scheme, when the thickness of the light guide plate is 4 mm and the interval of the LED is 5 mm, the obtained simulation result can obtain better uniformity and luminaire efficiency than other cases.

From the above scenario, we can get two excellent results. The methods used for these two results are different. The two configurations are respectively 1. The light is incident on both sides, the thickness of the light guide plate is 4 mm, and the interval between the LEDs is 5 mm. 2. Single side light, the thickness of the light guide plate is 4mm, and the interval between the LEDs is 10mm.

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