THE IMPORTANT PARAMETERS OF LED DISPLAY
With the continuous development of the economy and society, the application range of LED displays has become more and more extensive. Whether you are walking in the streets or in the bustling city square and high-end entertainment venues, you can see the LED display. Following is LED Display Parameter Description.
It is the smallest unit that can be independently controlled on the screen. PIXEL is an abbreviation of pictureelement. On a three-color screen, pixels consist of three parts: red, green, and basket. Each part consists of one or several leds. Theoretically, they are individually adjusted. The brightness of red, green and blue can be expressed in any color.
The distance between the centers of adjacent pixels. The smaller the distance, the shorter the viewing distance.
Usually used for digital display devices, representing the total number of pixels, generally written in a wide X high form, such as 800X600.
The maximum brightness that can be seen when the observer is facing, when the viewer moves to the left or right, the brightness is reduced, and when the brightness is reduced to half of the maximum brightness, the angle at this time is added to the The sum of the angles obtained by moving in the opposite direction is called the horizontal viewing angle and the vertical viewing angle is measured in the same manner. The perspective manufacturers will give parameters.
Brightness is the most important parameter in any display device. The main unit of brightness is called candela, which is represented by CD. The brightness of a single LED is usually millicarandelas, MCD, ie one thousandth of a CD, and the brightness of one square meter of LEDs is added together to obtain the brightness per unit area. NITS says 1 NITS=1 CD/m2
For various LED displays, the best viewing distance should be the smallest distance that the human eye can't distinguish between pixels. This distance is about 3400 times the distance between points. The viewing distance between TV and computer is usually less than this requirement, but the acceptable distance can not be less than 1700 times the distance between points.
Picture update rate/refresh rate
The rate at which the screen image is updated, usually expressed in Hertz (Hz), is different from the frame rate.
The number of image frames displayed per second on the screen, usually depends on the input signal (25fpsforPAL, 30fpsforNTSC)
Half frame of PAL and NTSC, because PAL and NTSC are interlaced scanning, only reveal the half frame picture every refresh.
Pure green and true green
In the past 30 years, various colors of LEDs have been successively developed. First, red, yellow, yellow-green, blue LEDs and pure green LEDs were successively invented by Nichia engineers in the 1990s. It is now possible to manufacture LED full-color screens. The video LED screen must use pure green. If you use yellow green, the color is definitely not true. If the number of green tubes in a pixel is more than the number of red and blue tubes, it must be a yellow-green tube, because yellow The brightness of the green is not enough, you must use more than one, but the yellow-green LED is cheap.
The brightness of red, green and blue must be balanced to accurately restore the true color. In other words, the white color of the LED must be white instead of pink. If red, green and blue are all at the highest brightness, the mixed colors are usually not white. In order to get white (usually called 6500K color temperature), one or two of the red, green and blue lights must be turned down. To get the correct white color, you must Measured repeatedly to adjust the brightness, this process called white balance, LED display price.
The number of colors that an LED screen can represent depends on the RGB three-color gray scale. In a standard full-color screen, it is 256 levels of gray. For stadium full-color LED systems, 256 gray levels are not enough to accurately recover Restore color. Also known as color depth, refers to the number of different brightness, red, green and blue have their own grayscale, in a full-color system is generally 256 levels of gray, can produce 256X256X256 = 16,777,216 kinds of colors, called 24-bit color in PC, It is called an 8-bit system in LED display systems.
This is a way to reduce the number of gray scales by transforming functions to produce a color and contrast that is closer to the real environment. The actual color of full-color screens is subject to many restrictions. At night, the brightness of the screen body must be reduced. The color will be reduced, therefore, the digital RGB display color is certainly less than the 16M color, in order to solve this problem, you need a higher level of gray, 1Bill color system (red, green and blue 1024 color) can be more realistic color , because from the 256 gray scale expanded to 1024, greatly enriched the number of colors that can be expressed.
Virtual Pixel Technology
Also known as a shared pixel or a dynamic pixel, a pixel that is 4 times the physical pixel is rapidly sent to the physical pixel by parity and even-odd rows. The effect is equivalent to reducing the pitch by half, and the cost is basically the same as the conventional method. Compared to the basic increase, but it can do 4 times the original resolution.
The quality of the entire picture largely depends on the consistency of the LED. The problem of consistency is the inherent problem of LEDs when LEDs are produced. Their brightness, viewing angle, and other characteristics are actually not uniform. These parameters are distributed in a certain range. The better the manufacturer's process control, the smaller this range, and the use of LEDs provided by high-quality manufacturers can reduce the workload of debugging. The sensitivity of the human eye to color and brightness is quite high, and the difference between LEDs is easily noticeable, especially in high-brightness display systems. Designers must adopt various techniques to eliminate this difference. , increase consistency, LED display manufacturers.
LED large-screen combination of red, green and blue to produce a variety of colors, but these three colors are made of different materials, the viewing angle is different, the spectrum distribution of different LED are changed, these differences can be observed It is color difference. When observing the LED at a certain angle, its color changes, and the ability of the human eye to judge the color of the real picture (such as a movie picture) is better than the picture produced by the observation computer.