23 /Feb / 2023Embedded World 2023
15 /Feb / 2023How to Prevent Electromagnetic Interference for TFT Display?
Using a TFT display, people will not only be affected by electromagnetic fields, but also by other communication equipment, which is EMI. When operating, they act as electromagnetic sources, forming a magnetic field around them and radiating electromagnetic waves outward. The magnitude of the field strength and radiation force depends on the power of the device.
The TFT display screen itself has no error correction function, that is, the TFT display screen can receive any signal that satisfies the satisfactory action timing relationship, and there is no need to judge whether it is right or wrong. Incorrect signals and data will cause incorrect control commands or incorrect display images, resulting in incorrect display effects. To eliminate interference, we must first find out the source of interference and the affected part, and then use effective means to eliminate, weaken, shield and remedy.
The TFT display does not display, and there is no response to changing the contrast. The reason for this phenomenon is that when the machine is complete, the power line or signal line of the TFT display is subject to electromagnetic interference, which causes the TFT display to reset. The result of the reset is to initialize the internal registers of the module while turning off the display.
The following method is recommended: If interference is applied to the power line, it is recommended to combine the voltage stabilizing capacitor (10uf) and filter capacitor (0.1uf or 0.01pf) to the power line VDD closest to the TFT display. If there is interference to the signal line, it is recommended to add the VSS signal to the signal closest to the TFT display screen, and the capacitor should be 0.1uf or 0.01uf. The above capacitance values are determined according to actual test results.
Drawings will be typo or garbled (data error), or drawings will be shifted, upside down. Sometimes it cannot be restored, but can only be rewritten by clearing the screen, or even restarting, and the initialization register can be restored. This is mainly due to interference with control signals, such as /WR, RD, E, or /CS, which all create interference.
On these signal lines, interference signals can easily generate incorrect waveforms, resulting in wrongly modifying register parameters and writing data to the display unit by mistake; when the system is running, most programs only write data in the local display area, and there is no right Other addresses are written, and there is no situation where only the initialization register is repeatedly set.