How to control radiation from the LCD screen of an HMI (Human Machine Interface)?

Controlling the radiation from an HMI LCD screen requires addressing its driver circuitry, backlight circuitry, and connecting cables separately. The LCD screen's own radiation primarily originates from the switching noise and clock signal of the row/column driver chips. Decoupling capacitors should be placed near the power pins of the driver chips, and ferrite beads, such as the PBZ1608E121Z0T, can be connected in series on the power path. For the signal lines output by the driver chips, small resistors can be connected in series, if space permits, to mitigate edge noise. The backlight circuitry, especially the switching frequency and harmonics of the LED drivers, is a strong source of radiation and should be completely shielded, or shielding should be used at the switching nodes. The LVDS or RGB cables connecting the LCD screen to the main control board are radiating antennas and must be shielded, with the shielding layer connected to their respective ground planes at both ends using low impedance. In PCB layout, the LCD screen interface circuitry should be kept away from other high-frequency circuits in the system and isolated with grounded copper foil. The metal frame of the LCD screen should be tightly connected to the front panel metal frame of the HMI device using conductive foam or metal springs to form a continuous shielded cavity. Furthermore, applying a transparent conductive film to the glass surface of the LCD screen and grounding it can further suppress radiation. By comprehensively utilizing filtering, shielding, and grounding technologies, and selecting high-frequency ferrite beads and shielding materials from Audiotech, the radiation emissions of the LCD screen can be controlled within standard limits.