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How does LED solid-state lighting surpass traditional lighting
by：ALLTOP
2021-04-07
At the high-end lighting designer forum held in Kunming at the end of the year, I gave a report 'Re-discussion of the Four Elements of Green LightingWith the advancement of light source technology and the improvement of standards, the safety and comfort of light can also be discussed in depth. QQ mobile //./
Solid-state lighting includes LED and OLED. At present, OLED has not been widely used in general lighting, so this article mainly discusses LED. With the elimination of incandescent lamps and the gradual withdrawal of high-pressure mercury lamps, the scope of traditional lighting has shrunk. At present, it mainly includes light sources such as tungsten halogen lamps, fluorescent lamps, high-pressure sodium lamps, and metal halide lamps, as well as supporting electrical appliances and lamps.
The indicators for evaluating energy conservation are the luminous efficiency, life span and luminous flux maintenance rate of light sources and lamps. Environmental protection indicators are the emissions of hazardous substances during production, transportation, operation, abandonment and recycling, and the corresponding emissions of electrical energy consumed during operation. LED does not contain harmful luminous substances such as mercury, and its luminous efficiency, life span, and luminous flux maintenance rate exceed those of traditional light sources. Therefore, its advantages in energy saving and environmental protection have been recognized by everyone.
In terms of safety, all light sources and lamps need to comply with mandatory electrical safety standards. Only the blue light hazard of photobiological safety is discussed here. The comfort index includes color temperature, color rendering index, color tolerance and glare index. Traditional light sources have been used for a long time, which is equivalent to setting a threshold in terms of photobiological safety and light quality. Has LED surpassed traditional lighting?
1. Light quality
Comfortability is determined by the light quality of the light source, including spectrum, color temperature, color rendering index, color tolerance, spatial color uniformity, glare index, stroboscopic and color stability during life.
At present, the mainstream LED uses blue light chips to excite yellow phosphors to produce white light, which belongs to the continuous spectrum in the visible region, but the green light area is weaker and the red light area is less. Therefore, the spectral continuity of LEDs is obviously stronger than that of fluorescent lamps, but not more than ceramic metal halide lamps. Generally, the red special display index (R) of LED only requires>, which cannot restore the deep red color well. Therefore, after the Great Hall of the People was remodeled with LEDs, the Red Five-Star still uses halogen tungsten lamps.
If you want to improve the color rendering of deep red, you should add red phosphor or red light chip in the LED package device.
The color rendering index of indoor occasions is very important. If you align with the tungsten halogen lamp and the ceramic metal halide lamp, the color rendering index of the LED needs to be above, and it is also necessary to increase the red phosphor or red light chip. During the lifetime, the color temperature and color coordinates of the light source must be stable. This puts high demands on the aging resistance of LED phosphors and encapsulated silica gel.
Spatial color uniformity is not a problem for traditional light sources, but it is more difficult to solve for LEDs. Since the blue light of the LED chip is still about/will be emitted and mixed into white light, and the spatial light uniformity of the chip and the phosphor is different, this will cause the spatial color coordinate to shift, and even colored light will appear around the white light. This problem is more serious for the multi-color LED mixed light lamps of intelligent lighting, and it is a problem that needs to be solved in the future.
2. Blue light hazards
The weighted radiance of blue light for evaluating blue light hazards is directly proportional to the brightness, and the brightness of the light source can vary up to twice, so the blue light hazard is mainly determined by the brightness of the light source. By controlling the brightness of the light source, the blue light hazard is also controlled. For a light source with a color temperature lower than K, as long as its brightness does not exceed kcdm-, or the illuminance does not exceed lx, it is blue safe (class, non-hazardous). For light sources with higher brightness, if they are classified in the low-risk category (class), the use of the light source is not restricted as long as direct viewing is avoided.
The weighted radiance of blue light for evaluating blue light hazards is directly proportional to the brightness, and the brightness of the light source can vary up to twice, so the blue light hazard is mainly determined by the brightness of the light source. By controlling the brightness of the light source, the blue light hazard is also controlled. For a light source with a color temperature lower than K, as long as its brightness does not exceed kcdm-, or the illuminance does not exceed lx, it is blue safe (class, non-hazardous). For light sources with higher brightness, if they are classified in the low-risk category (class), the use of the light source is not restricted as long as direct viewing is avoided.
Of course, since the brightness of LED light sources and lamps is larger, special attention should be paid to controlling glare when designing lighting. Generally speaking, as long as the brightness of white LED light sources and lamps for general lighting is controlled, the blue light hazard is within a safe range.
Solid-state lighting includes LED and OLED. At present, OLED has not been widely used in general lighting, so this article mainly discusses LED. With the elimination of incandescent lamps and the gradual withdrawal of high-pressure mercury lamps, the scope of traditional lighting has shrunk. At present, it mainly includes light sources such as tungsten halogen lamps, fluorescent lamps, high-pressure sodium lamps, and metal halide lamps, as well as supporting electrical appliances and lamps.
The indicators for evaluating energy conservation are the luminous efficiency, life span and luminous flux maintenance rate of light sources and lamps. Environmental protection indicators are the emissions of hazardous substances during production, transportation, operation, abandonment and recycling, and the corresponding emissions of electrical energy consumed during operation. LED does not contain harmful luminous substances such as mercury, and its luminous efficiency, life span, and luminous flux maintenance rate exceed those of traditional light sources. Therefore, its advantages in energy saving and environmental protection have been recognized by everyone.
In terms of safety, all light sources and lamps need to comply with mandatory electrical safety standards. Only the blue light hazard of photobiological safety is discussed here. The comfort index includes color temperature, color rendering index, color tolerance and glare index. Traditional light sources have been used for a long time, which is equivalent to setting a threshold in terms of photobiological safety and light quality. Has LED surpassed traditional lighting?
1. Light quality
Comfortability is determined by the light quality of the light source, including spectrum, color temperature, color rendering index, color tolerance, spatial color uniformity, glare index, stroboscopic and color stability during life.
At present, the mainstream LED uses blue light chips to excite yellow phosphors to produce white light, which belongs to the continuous spectrum in the visible region, but the green light area is weaker and the red light area is less. Therefore, the spectral continuity of LEDs is obviously stronger than that of fluorescent lamps, but not more than ceramic metal halide lamps. Generally, the red special display index (R) of LED only requires>, which cannot restore the deep red color well. Therefore, after the Great Hall of the People was remodeled with LEDs, the Red Five-Star still uses halogen tungsten lamps.
If you want to improve the color rendering of deep red, you should add red phosphor or red light chip in the LED package device.
The color rendering index of indoor occasions is very important. If you align with the tungsten halogen lamp and the ceramic metal halide lamp, the color rendering index of the LED needs to be above, and it is also necessary to increase the red phosphor or red light chip. During the lifetime, the color temperature and color coordinates of the light source must be stable. This puts high demands on the aging resistance of LED phosphors and encapsulated silica gel.
Spatial color uniformity is not a problem for traditional light sources, but it is more difficult to solve for LEDs. Since the blue light of the LED chip is still about/will be emitted and mixed into white light, and the spatial light uniformity of the chip and the phosphor is different, this will cause the spatial color coordinate to shift, and even colored light will appear around the white light. This problem is more serious for the multi-color LED mixed light lamps of intelligent lighting, and it is a problem that needs to be solved in the future.
2. Blue light hazards
The weighted radiance of blue light for evaluating blue light hazards is directly proportional to the brightness, and the brightness of the light source can vary up to twice, so the blue light hazard is mainly determined by the brightness of the light source. By controlling the brightness of the light source, the blue light hazard is also controlled. For a light source with a color temperature lower than K, as long as its brightness does not exceed kcdm-, or the illuminance does not exceed lx, it is blue safe (class, non-hazardous). For light sources with higher brightness, if they are classified in the low-risk category (class), the use of the light source is not restricted as long as direct viewing is avoided.
The weighted radiance of blue light for evaluating blue light hazards is directly proportional to the brightness, and the brightness of the light source can vary up to twice, so the blue light hazard is mainly determined by the brightness of the light source. By controlling the brightness of the light source, the blue light hazard is also controlled. For a light source with a color temperature lower than K, as long as its brightness does not exceed kcdm-, or the illuminance does not exceed lx, it is blue safe (class, non-hazardous). For light sources with higher brightness, if they are classified in the low-risk category (class), the use of the light source is not restricted as long as direct viewing is avoided.
Of course, since the brightness of LED light sources and lamps is larger, special attention should be paid to controlling glare when designing lighting. Generally speaking, as long as the brightness of white LED light sources and lamps for general lighting is controlled, the blue light hazard is within a safe range.
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