What faults will occur when the voltage of the LED full-color display screen is unstable?

14 views admin 2025-01-03

From simple P-MOSFET to achieve line switching, to more integrated and powerful multi-functional line drivers. The display quality of LED display screens has always been closely related to the input voltage. So what problems or faults will occur when its voltage is unstable?

From simple P-MOSFET to achieve line switching, to more integrated and powerful multi-functional line drivers. The display quality of LED display screens has always been closely related to the input voltage. So what problems or faults will occur when its voltage is unstable?

If the voltage difference between VLED and point A is greater than the luminous value of the LED lamp bead, a column of constant voltage will be formed, that is, a bright caterpillar. The difference between the short-circuit caterpillar and the open-circuit cross is that as long as the screen is in the scanning state, the short-circuit caterpillar will appear, regardless of whether the LED lamp bead displays an image.

Lamp tube reverse voltage When the output channel is closed, due to the freewheeling effect of the parasitic inductance, the parasitic capacitance at the channel will continue to charge, forming a high-voltage burr. At this time, the reverse voltage loaded on the lamp bead is formed with the output of the line tube, so the blanking voltage of the line tube also affects the reverse voltage of the lamp bead. In fact, after manufacturer testing, a reverse voltage below 1.4V can greatly reduce the bad pixels caused by the reverse voltage. Therefore, for the reverse voltage problem of the lamp tube, the blanking voltage should not be too low. Generally not less than VCC-2V.

Open cross hidden bright. Lowering the blanking voltage of the blanking line tube can solve the problem of open cross, that is, the blanking voltage VH <1.4V. Some line tubes in the industry also use the method of adjustable blanking voltage to reduce the blanking voltage to below 1.4V to solve the open cross, but this will increase the LED back pressure and accelerate the damage and short circuit of the LED lamp beads - giving the caterpillar a circle.