LED panel light uniformity
Another important indicator of LED panel lights is the uniformity of their luminescence. The cross-strait common standard GT004-2012 "LED Flat Lights for Indoor General Lighting" puts forward the requirements of luminance uniformity (luminance uniformity), which refers to the minimum brightness and brightness on the light-emitting surface of the luminaire The ratio of the arithmetic mean.
As an LED panel light, the non-uniformity of light emission will cause the unevenness of the panel display brightness, causing discomfort to the human eye. According to the requirements of GT004-2012 standard, the brightness uniformity of LED flat panel lamps should not be less than 0.8. The test method is mainly to select appropriate test points according to the size of the screen, and measure the brightness value of each point. It is generally believed that a uniform performance of more than 80% has little effect on the perception of the human eye.
The brightness uniformity test of flat-panel luminaires is the first time that the requirements for the surface brightness of indoor luminaires are put forward in the standard. It reflects the characteristic parameters of flat panel lamps and is one of the important features of this type of lamps. In indoor lighting, surface-emitting luminaires create a soft and simple lighting effect that cannot be replaced by other bracket luminaires or grille luminaires.
In indoor lighting, fluorescent lamps with diffusers also have a surface luminous effect. They have been used for many years, but they cannot reach the level of brightness uniformity of LED panel lamps.
The reason is that the fluorescent tube is an omnidirectional light source, and the optical system cannot be adjusted to achieve better brightness uniformity, and the lamp efficiency is at the level of 40lm/W. The light source of LED lamps emits light in half space. In the lamp, the light utilization rate is high, and the lamp efficiency can reach more than 160lm/W, and the brightness uniformity can reach a higher level.
The side light guide structure LED panel light is adopted, and the LED light-emitting tube is arranged on the side of the light guide plate, and the visual effect of the lamp is better. At present, most domestic manufacturers still use printed light guide plates as light guide components, and use a variety of dense and different diffusion points to make the light guide plate emit light uniformly to obtain good light emission uniformity.
Judging from the test results, the brightness uniformity of small-size LED panel lights can easily meet the requirements. Even if the uniformity deviates a little, it is not easy for the human eye to perceive it. Large-area LED flat lights sometimes have uneven brightness due to the quality of the light guide plate, and process reasons cause the above-mentioned bright light band at the light entrance, or visible local dark areas.
Therefore, the selection of main raw materials such as light guide plates, diffusers, and reflective papers must be evaluated for quality, and the raw materials must be strictly checked when the raw materials enter the factory. The manufacturer should be equipped with the necessary optical brightness meters and light transmittance test instruments.
