With the maturity of LED display in the outdoor field, LED display has become the standard of major cities and urban business circles in major cities, but the light pollution caused by high brightness is often criticized by people. How to minimize the LED light pollution problem while ensuring urban demand? You can start with the LED display security brightness parameter settings and human security measures.
(1) Adjust the brightness of the LED screen according to the ambient brightness
The main purpose of brightness adjustment is to adjust the brightness of the LED screen according to the ambient light intensity, so that the LED display looks clear and bright without glare. Most of the domestic LED display manufacturers have already realized this function, but there are not many enterprises and users who really use this technology. On the one hand, there is a lack of accurate and easy-to-use environmental brightness detection equipment on the market. On the other hand, LED The display industry lacks adjustable specifications for reference.
When the human eye adapts to the ambient brightness of 800 candelas per square meter, the brightness range that can be seen is 80-8000 candelas per square meter. Any display content beyond this brightness range needs to be adjusted by the human eye to adapt and gradually see. For example, in an outdoor environment of 5,000 candelas per square meter, the brightness of the display device that is easy to view is about 500-50000 candelas per square meter. In this environment, if you want to clearly identify 60 candelas per square meter of mobile phone content, you need It is this truth that the human eye tries to adjust for a few seconds to gradually adapt.
According to this theory, it is possible to establish a design specification for the brightness adjustment method of the LED display. The gray scale range falls within a range suitable for comfortable viewing by the human eye according to the ambient brightness. Especially at night, the maximum brightness of the display should be less than 10 times the ambient brightness.
Relationship between ambient brightness and optimal output brightness of display devices
According to the curve of the ambient brightness from the morning to midnight, and the corresponding brightness setting curve of the corresponding (subjective) LED display, the test results show that the ambient brightness changes during the day is very obvious. When the brightness is the brightest, the brightness ratio at the darkest time can reach 30,000 to 1. The corresponding LED display brightness setting changes beyond imagination. In the night environment, when the LED display is set to 60cd, the LED screen is bright enough, but by noon during the day, even 5000-6000cd is not bright enough. The difference between light and dark is close to 100 times.
Due to the lack of specification constraints, many outdoor LED displays show very glare at night, causing serious light pollution to the surrounding environment and invisible damage to surrounding residents. It is recommended to establish industry standards as soon as possible, constrain corporate behavior, and force enterprises to install brightness adjustment devices. During the use of the LED display, the brightness output level of the LED display should be automatically adjusted according to the industry standard according to the change of the ambient brightness, and the high brightness of the LED display is prohibited in the dark environment.
(2) Specification of the blue output of the LED display
The human eye has different light perception abilities for different wavelengths. Since the brightness is a parameter based on the perception characteristics of the human eye, the brightness cannot be accurately reflected by the brightness alone. Irradiation is used as a measure of visible energy safety, which more accurately reflects the dose of light on the eye. The measured value of the irradiance metering device should be used instead of the brightness perception of the blue light by the eye as a basis for determining whether the blue light output intensity would cause damage to the eye. LED display manufacturers and users should reduce the blue output of LED displays under the conditions of display.
(3) Specification of the illumination distribution and direction of the LED display
The rationality of the light distribution of the LED should be considered as much as possible, and the light energy outputted by the LED is evenly distributed in all directions in the visible angle range, so that the small-angle LED light is directly directed to the human eye. At the same time, the direction and range of LED light should be limited to reduce the pollution of the LED display to the surrounding environment.
(4) Standardize the display output frequency
LED display manufacturers should design the display screen in strict accordance with the requirements of the LED display specification. The output frequency of the display screen meets the requirements of the specification to avoid discomfort to the viewer due to the flickering of the screen.
(5) Explicit safety measures in the LED display manual
In the LED display user manual, note the precautions for use, explain how to properly adjust the brightness of the LED display, and the long-term direct view of the LED display may cause harm to the human eye. When the brightness auto-adjustment device fails, manual adjustment should be used or the LED display should be turned off.
When encountering a dazzling LED display in a dark environment, the self-protection measure should be, do not look directly at the LED display for a long time or carefully identify the details on the LED display, try to avoid the LED being focused on the fundus after focusing through the eye. Spot, burn the retina.
(6) LED display design, production process protection measures
Design and production personnel will contact the LED display more frequently than the user. In the design and production process, it is necessary to test the LED overload operation state. Therefore, the design and production personnel are easy to be exposed to the strong light of the LED, and should pay attention to and take special protection measures for the LED display design and production process.
LEDs in the production and testing of outdoor high-brightness LED displays, the relevant staff should wear black sunglasses with 4-8 times the brightness attenuation, in order to see the LED display details up close. During the production and testing of indoor LED displays, the relevant staff must wear black sunglasses with a brightness reduction of 2-4 times. Especially for the staff who test the LED display in the dark environment, it is necessary to pay attention to safety protection. You must wear black sunglasses before you can look directly at the LED display.
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