How to Design and Select Light Diffusion Agent Based on LED Lamps ?

With the progress of society, people’s demand for a better life is improving. The revolutionary introduction of LED lamp in the lighting field will be a long-term lighting demand in the future, and the demand for energy-saving will be higher and higher. The well-known DLC and Energy star associations in the global industry upgrade their luminous efficiency standards every year, thus promoting the development of LED technology and energy-saving requirements [1].

For example, DLC will advance the energy efficiency standard to 5.0 in 2020, which will raise the light efficiency requirements of global lamps and lanterns to a new level, and the application requirements of optical diffuser products will also be greatly improved.

Light diffusion agent is an organic and inorganic chemical product with special processing and surface treatment, with a particle size of 1 ~ 10 μ m and a spherical chemical product with an average particle size of 1 ~ 4 μ m, as shown in figure 1 [2].

There are mainly two kinds of optical diffuser: inorganic diffuser and organic diffuser. This paper will focus on the application of organic light diffusion agent. Organic light diffuser mainly includes acrylic type, phenylethylene type and acrylic resin type [3]. The resin itself is transparent or translucent, and most of the light can pass through. Taking advantage of the difference between the refractive index of these light diffusers and that of the substrate, the light passing through the substrate becomes bright and soft after many times of refraction and has little effect on the light transmittance of the material. In this experiment, we focus on the simulation test and analysis of the application types of extrusion lampshade and extrusion lens.

1 test method and test scheme of lampshade.

1.1 Test method.
Take our light diffusion agent WD-102 as an example, using a low-voltage lamp, using the same technical parameters and electrical parameters, the lampshade is tested with different proportions of optical diffuser.

1.2 Test scheme.
A low-voltage lamp product, the maximum diameter of the lampshade is 20 mm, the thickness is 1 mm, the structure and form are shown in figures 2 and 3. The addition amount of diffuser is the number of grams per kilogram of base material (PC1250Z), and the integral times of 0.3 g, 0.6 g, 0.9 g, 1.2 g and 1.5 g are added. The remote brand GO-2000A distribution photometer equipment is used for testing.

1.3 Test results.

The test results are shown in Table 1.

It can be seen from Table 1 that for lampshade products, the light transmittance does not change when the diffuser ratio changes from 0 to 1.5 g.

Test method and scheme of optical lens.

2.1 Test method.
Two kinds of low-voltage lamps and lanterns, using the same technical and electrical parameters, using two kinds of optical lenses with different thickness, were tested under the same ratio of optical diffuser, and the light loss and angle changes of optical lenses with different lenses and the same ratio were obtained.

2.2 Test scheme.
Take our light diffusion agent WD-102 as an example. The thickest part of lens 1 is 5.6mm, and the thickest part of lens 2 is 2.8mm. The structural forms are shown in figs. 4, 5, 6 and 7. The addition amount of diffuser should be based on the weight of diffuser added in PC1250Z, and the integral times of 0.3 g, 0.6 g, 0.9 g, 1.2 g and 1.5 g should be added. The far brand GO-2000A distribution photometer equipment is used for testing.

2.3 Test results.

The test results are shown in Table 1.
It can be concluded from Table 2:
The main results are as follows: (1) when the diffuser ratio of lens 1 increases from 0 (transparent) to 1.5 g, the light loss increases, the light efficiency decreases and the luminous angle increases. When the lowest and highest are added, the difference in light transmittance is 6.5%, and the luminous angle is increased by 3.5 times. Combined with the problem of color difference, it is suggested that the dosage ratio of light diffusion agent should be 0.3 ~ 0.6 g.

(2) when the diffuser ratio of lens 2 increases from 0 to 1.5 g, the light loss increases, the light efficiency decreases and the luminous angle increases. When the addition ratio is the lowest and the highest, the difference in light transmittance is 3.5%, and the luminous angle is doubled. Combined with the problem of color difference, it is suggested that the ratio of light diffusion agent should be 0.6 ~ 0.9 g.

3 optical principle model.

Figure 8 shows the scattering of diffused particles when the incident light passes through the scratch-resistant layer and the diffusion layer. Assuming that the incident light passing through the object is a lens material with a light diffuser, the beam angle of a beam of light passing through the lens will change with the addition ratio of the light diffuser. The higher the ratio, the more light scattered and the larger the angle. The principle of light transmission [4], as shown in figure 9.

Fig. 9 schematic diagram of light transmission ( showed in pic a, b, c)

4 Conclusion

In this experiment, the simulation measurement method is used to compare and analyze the actual test and analysis of LED lampshade and lens adding light diffuser, and verified by the test, it can be concluded that:

The main results are as follows:

(1) the optical diffuser has little effect on the light efficiency of lampshade with uniform thickness, and the proportion of diffuser can be selected according to the actual demand in design.

(2) the influence on the lens products, with the increase of the diffuser ratio, the thickness of the lens has a great influence on the luminous angle, so the influence of the lens thickness on the luminous angle should be fully considered in the design. In this paper, the simulation and measurement method is used to compare the lampshade, lens and lens, which provides a certain reference basis for the secondary light distribution design of LED lamps and lanterns, shortens the progress of product development, saves the cost of trial and error, and provides an effective design reference for the design of similar LED lamps and lanterns.