1. Uneven block and color cast (reddish)
In indoor applications, LED display brightness is mostly between 300 to 1000nit, this brightness is converted into LED forward current, equivalent to 1 ~ 5mA, or even less than 1mA. Therefore, the driving current density of the chip becomes very important. When the drive chip current accuracy is poor, the dot pitch LED display is prone to uneven blocks of color, however, in order to cover up the defects of the color block, LED current is usually taken to increase the means to increase the brightness of the display. But the disadvantage is that when the viewer looks at the LED display for a period of time, the eyes can feel uncomfortable.
2. Low light image detail loss
If not to raise the LED forward current way to cover the above shortcomings, another means is to adjust the gamma curve of the small dot pitch LED display, the brightness of the gray scale for the correct image reproduction is very important because the video source Medium brightness contains most of the screen data. As shown in Fig. 3, the gamma value of the image on the right is smaller, indicating the brightness of the middle tone is too high. Therefore, the overall picture is white and lacks in depth, and the details of the image are greatly lost.
3 .Is not smooth gray scale performance Dot-to-dot LED displays are time-multiplexed displays, hold-type displays that are not LCD screens, so refresh rates are important for small-pitch LED displays, and lower refresh rates not only make small Point spacing LED display with a flickering discomfort, easy to cause the viewer dizzy, but also the effect of graded gradation is not smooth.
4.LED dead pixels caused by bright lines or crosses Today's LED epitaxy and packaging technology is increasing, but the LED after a long period of use will inevitably be damaged, and the LCD screen is different, broken LED LED display in the small space between the formation of bright lines or crosses, Not a black spot.