Due to itc bright colors and clear picture quality, LED display screen is increasingly popular in the public indoor field. Therefore, the EMC design and certification standards related to health and safety are more stringent. At present, there is an urgent need for LED display screens to pass EMC certification.
EMC testing is one of the most important indicators of product quality and an important part of 3C certification. The 3C standard is a mandatory product certification system to protect consumer rights and safety, strengthen product quality management and implement a legal product evaluation system.
EMC testing is called electromagnetic compatibility, which is a comprehensive evaluation of the Electro Magnetic Interference (EMI) and Electro Magnetic Susceptibility (EMS) of electronic products.
LED display adjusts the current pulse parameters on the luminotron to achieve high refresh rate. Therefore, its power supply, control card, and internal signal transmission will all produce electromagnetic radiation. The higher the refresh rate of the display, the higher the frequency of the signal on the system card, and the stronger the radiation interference.
In order to effectively improve the electromagnetic susceptibility of the LED display, itc uses PWM enhancement technology, spread spectrum technology, and hardware adjustment to pursue the highest quality standard.
Figure 2 EMI with/without PWM enhancement technology
The spread spectrum technology is known as one of the most advanced and effective active EMI suppression methods today. On the basis of ensuring the integrity of the clock signal, the EMI peak is suppressed by modulating the frequency of the internal integrated circuit of the clock. The clock and timing signals obtained from the spread spectrum clock will modulate the spread spectrum effect of the corresponding multiple. Therefore, it has a significant effect on suppressing higher harmonics, and the overall EMI peak is thus reduced.
Figure 3 EMI of enabling/disabling spread spectrum technology
The module uses resistors, capacitors, inductors, magnetic beads and other components to form RC filter circuit, suppressing electromagnetic interference and filtering out high-order high-frequency harmonics to reduce the rise and fall time of clock signal. Besides, high-frequency signal line is covered with the principle of less drilling, less turning, and less layer change, and the PCB board is wrapped with metal, so that the microwave signal cannot be radiated from the PCB board edge, reducing radiation.
Over the years, itc has been concentrating on R&D, and constantly innovating and reforming technical means to create high-standard and high-quality LED displays. Now, itc LED display has not only passed the national 3C compulsory certification but also obtained a series of certificates such as CE, CAQI, CQC and international ISO quality management system certificates.
itc successful LED cases cover finance, cultural tourism, theaters, campuses, enterprises, hotels, government, cultural and sports venues and other places.
