What Is Electromagnetic Interference of Monitor (EMI)?

When people use LCD display equipment, they are not only affected by the earth’s magnetic field but also more or less affected by other equipment and communication equipment, which is also called Electromagnetic Interference. When devices are working, they become an electromagnetic source, forming a magnetic field around them and radiating electromagnetic waves outward. The size of the magnetic field and the intensity of the radiation are determined by the power of these devices.

What Is Electromagnetic Interference?

Electromagnetic Interference (EMI) is electronic noise that interferes with cable signals and reduces signal integrity. EMI is typically generated by sources of electromagnetic radiation such as motors and machines, an electromagnetic phenomenon that has been discovered for a long time.

What Is Electromagnetic Compatibility?

The FCC in 1990 and the European Union in 1992 introduced regulations for commercial digital products that require companies to ensure that their products meet strict susceptibility and emission guidelines. Products that comply with these regulations are called Electromagnetic Compatibility EMC (Electromagnetic Compatibility). There is the EMC Test in Certificates.

https://hmivision.com/certificates/

What Are the Main Interference Sources?

Naturally occurring interference– This type of EMI can arise from various natural sources and phenomena such as atmospheric types of noise like lightning or electrical storms.

Man-made interference- This type of EMI generally occurs due to the activities of other electronic devices in the vicinity of the device (also known as the receiver) experiencing the interference.

Display itself interference- Regular display or monitor is compliant to EMCthe FCC/RoHS/CE Certificates, which has the EMC testing.

(1) Power supply (including power adapter)

(2) DC/DC Converter

How to Prevent or Reduce Electromagnetic Interference?

For a better solution, the proper design of all equipment minimizes emissions and/or makes the equipment less vulnerable to external interference.

There are three different methods to help reduce or eliminate EMI:  filtering, grounding, and shielding. 

1. Filtering

A direct way to get rid of unwanted signals is through filtering them out, and in this instance, passive filters work well, and they’re used in most new equipment to minimize EMI, but cannot be eliminated.

Filtering usually starts with an AC line filter that prevents bad signals from entering the power supply or powered circuits. It keeps internal signals from being added to the AC line.

2. Shielding

Shielding is crucial because it reflects electromagnetic waves into the enclosure and absorbs waves that aren’t reflected.
In most cases, a small amount of radiation ends up penetrating the shield if it’s not thick enough. Practically any common metal can be used for shielding (e.g. copper, steel, aluminum).

3. Grounding

Some best practices to keep in mind to achieve the best possible ground include:
–Keep leads away from internal circuits or other components to ground as short as possible to reduce inductance.
Use multiple grounding points on a large ground plane for best results.
–Try to isolate circuits from the ground if ground loop voltages can’t be controlled any other way.
–Maintain separate grounds for analog and digital circuits– you can combine them later at a single point.
Utilizing any one of these three methods above can help you not only reduce EMI but can help ensure your equipment is less vulnerable to future interference and can assist with reducing emissions.

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