The publication and implementation of the "LED Display Test Method" industry standard (hereinafter referred to as "Standard"), to correctly guide users to understand the performance indicators of full-color LED displays, is of great significance for regulating the LED display market. The following article will talk about common performance indicators, how much do you know? Let's take a look:
1. Maximum output current: At present, the maximum output current of the mainstream constant current source LED driver chip is about 90mA per channel. The maximum value of each channel outputting constant current at the same time is more meaningful to the display screen, because in the white balance state, it is required that each channel simultaneously output constant current.
2. The number of constant current output channels: constant current source output channels are available in 8-bit and 16-bit specifications. Now 16-bit is the mainstream. Its main advantage is that it reduces the chip size and facilitates the wiring of the LED driver board (PCB), especially for The LED driver board with a smaller dot pitch is more advantageous.
3. Accurate current output: one is the current error value between channels of the same chip; the other is the output current error value between different chips. Accurate current output is a key parameter, which has a great influence on the display uniformity of full-color LED display. The larger the error, the worse the display uniformity, and it is difficult to achieve white balance for the screen. At present, the bit-to-bit current error of mainstream constant current source chips is generally within ± 3, and the chip-to-chip current error is within ± 6.
4. Data shift clock: It determines the transmission speed of the display data and is a key indicator that affects the update rate of the LED display screen. As a large-sized display device, the display refresh rate should be above 85Hz to ensure a stable picture (no scan flicker). A higher data shift clock is the basis for the display to obtain a high refresh rate picture. At present, the shift clock frequency of the mainstream constant current source driver chip is generally above 15MHz ~ 25MHz.
5 Duty cycle is like the "performance principle" mentioned above. "Whenever possible, the requirements should be expressed by performance characteristics, rather than by design and description characteristics. This method leaves the greatest scope for technological development." We believe that "duty cycle" is purely a design technology requirement, and should not be used as a performance indicator of LED display product standards; everyone understands that any user will care about the drive duty cycle of full-color LED display What they care about is the effect of full-color LED displays, not our technical realization; why should we manufacture such technical barriers ourselves to limit the technological development of the industry?
The biggest advantage of full-color LED display is that the manufacturing is not limited by the size of the area, and can reach more than tens or even hundreds of square meters. It is used in indoor / outdoor public places to display text, graphics, images, animations, video images, etc. Various information, and with the improvement of various performance indicators of full-color LED display, full-color LED display will be more widely used.
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