Today, LED display screens are widely used in various fields. The shadow of LED display screens can be seen everywhere in outdoor wall advertisements, squares, stadiums, stages, security fields, etc. However, the light pollution caused by its high brightness is also a headache. Therefore, as LED display screen manufacturers and users, some measures should be taken to reasonably set the brightness parameters and safety protection of LED display screens to reduce the negative impact caused by brightness. Next, let's learn about the knowledge points of LED display screen brightness.
1. LED display screen brightness range
Generally, the brightness range of indoor LED display screens is recommended to be around 800-1200cd/m2, and it is best not to exceed this range. The brightness range of outdoor LED display screens is around 5000-6000cd/m2, which should not be too bright, and some places have already restricted the brightness of outdoor LED display screens.
For display screens, it is not the case that the higher the brightness is, the better. There should be a limit. For example, the maximum brightness of an outdoor LED display screen is 6500cd/m2, but you want to adjust the brightness to 7000cd/m2, which has exceeded its tolerance range. It is like the capacity of a tire. If a tire can only be filled with 240kpa, but you are afraid of air leakage or insufficient air pressure during driving, you must fill it with 280kpa. Then you may not feel anything when you just start driving, but after driving for a long time, because the tire cannot withstand such a large air pressure, it may malfunction, and in serious cases, a tire blowout may occur.
2. Negative effects of too high brightness of LED display screen
Similarly, the brightness of the LED display screen is appropriate. You can consult the LED display screen manufacturer. You can adjust the maximum brightness without causing negative impact on the LED display screen. However, it is not recommended to adjust the brightness as high as possible. If the brightness is adjusted too high, it will affect the life of the LED display screen.
(1) Impact on the service life of LED display
Because the brightness of LED display is related to LED diode, and the physical brightness and resistance value of the diode have been set before the LED display leaves the factory, the higher the brightness, the greater the current of LED diode, and the LED lamp will also work under this overload condition. If this continues for a long time, it will accelerate the service life and light attenuation of LED lamp.
(2) Power consumption of outdoor LED display
The higher the brightness of LED display, the higher the module current, and thus the greater the power of the whole screen, and the greater the power consumption. If it is calculated based on 1500W per hour (1000W is 1 kWh), 10 hours a day, 1 kWh is 1.5 yuan, and 30 days a month, then the annual electricity bill is: 1.5*10*1.5*30*12=8100 yuan; if it is calculated based on normal power, if 1.2 kWh per hour, then the annual electricity bill is 1.2*10*1.5*30*12=6480 yuan. Comparing the two, it is obvious that the former wastes more electricity.
(3) Damage to human eyes
The brightness of sunlight during the day is 2000cd, and the brightness of outdoor LED display screens is generally within 5000cd. If it exceeds 5000cd, it is called light pollution, and it will cause great damage to human eyes. Especially at night, the brightness of the display screen is too high, which will irritate people's eyes and make them unable to open their eyes. Just like at night, the environment around you is very dark, and suddenly someone shines a flashlight into your eyes, then you will not be able to open your eyes. Then, the LED display screen is equivalent to a flashlight. If you are driving, it may cause a traffic accident.
3. LED display screen brightness setting and protection
First, adjust the brightness of the outdoor LED full-color display screen according to the environment. The main purpose of brightness adjustment is to adjust the brightness of the entire LED screen according to the intensity of the ambient light, so that it looks clear and bright without being dazzling. Because the ratio of the brightness at the brightest time to the brightness at the darkest time on a sunny day can reach 30,000 to 1. The corresponding brightness setting varies greatly. However, there is currently no configuration for brightness specification. Therefore, users should adjust the brightness of the LED electronic display screen in time according to changes in the environment.
Second, standardize the blue output of outdoor LED full-color display screens. Because brightness is a parameter based on the perception characteristics of the human eye, the human eye has different perception capabilities for light of different wavelengths. Therefore, brightness alone cannot accurately reflect the intensity of light, and using irradiation as a measure of visible light safety energy can more accurately reflect the dose of light acting on the eyes. The measured value of the irradiance metering equipment, rather than the eye's brightness perception of blue light, should be used as the basis for judging whether the intensity of blue light output will cause damage to the eyes. Outdoor LED display manufacturers and users should reduce the blue light output component of the LED display screen under the conditions of meeting the display.
Third, standardize the light distribution and direction of the LED full-color display screen. Users should try to consider the rationality of the light distribution of the LED electronic display screen, and evenly distribute the light energy output by the LED in all directions within the visible angle range to avoid the strong light of the LED at a small viewing angle directly hitting the human eye. At the same time, the direction and range of LED light irradiation should be limited to reduce the pollution of the LED display screen to the surrounding environment.
Fourth, standardize the output frequency of the full-color screen. LED display manufacturers should design display screens in strict accordance with the requirements of the specifications, and the screen output frequency should meet the requirements of the specifications to avoid discomfort to viewers due to screen flickering.
Fifth, express safety measures in the user manual. LED display manufacturers should indicate the precautions for use in the LED display user manual, explain the correct method of adjusting the brightness of the full-color screen, and the possible harm to the human eye caused by looking directly at the LED display for a long time. When the automatic brightness adjustment device fails, manual adjustment should be adopted or the LED display should be turned off. When encountering a dazzling LED display in a dark environment, the self-protection measure should be not to look directly at the LED electronic display for a long time or carefully identify the details of the picture on the LED electronic display, and try to avoid the LED forming bright spots on the fundus after focusing on the eyes, which will burn the retina.
Sixth, take protective measures during the design and production process of LED full-color display screens. Design and production personnel will contact LED displays more frequently than users. It is necessary to test the overload operation status of LED during the design and production process. Therefore, design and production personnel are more likely to be exposed to the strong light of LED, and should pay more attention to and take special protective measures in the design and production process of LED display screens. During the production and testing of outdoor high-brightness LED displays, relevant staff should wear black sunglasses with a brightness attenuation of 4-8 times to view the details of the LED display at close range. During the production and testing of indoor LED displays, relevant staff must wear black sunglasses with a brightness attenuation of 2-4 times. Especially for staff testing LED displays in dark environments, they should pay more attention to safety protection and must wear black sunglasses before looking directly at them.
4. How LED display manufacturers deal with display brightness
(1) Replacement of lamp beads
In response to the negative impact of too high brightness of LED displays, LED display manufacturers replace conventional lamp beads with lamp beads that can support high-brightness displays. For example, the chip of the National Star high-brightness SMD3535 lamp bead has been replaced with a chip that can support brightness, so the brightness can be increased by several hundred cd to about 1,000 cd.
(2) Automatically adjust brightness
At present, general control cards can adjust brightness at regular intervals. Some control cards can add a photoresistor to automatically adjust brightness. LED display manufacturers use LED control cards and light sensors to measure the brightness of the surrounding environment. According to the measured data changes, they are converted into electrical signals and transmitted to the single-chip microcomputer. The single-chip microcomputer then processes these signals and controls the duty cycle of the output PWM wave in a certain order. The voltage of the LED display is adjusted by the switch voltage regulation circuit, so that the brightness of the LED display is automatically controlled, which greatly reduces the interference of the brightness of the LED display to people.
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