Both LED and LCD screen are very common products in daily life. In particular, LCD is more common than LED. Like the mobile phones and computers we use every day, most of them are made of LCD. On the device, LCD occupies an absolute position.
From the name point of view, the LED and LCD screen can be said to be very similar, and even the letters are not much different. So what is the difference between them? Let’s take a look.
What is LED display?
The LED display screen is a flat display composed of light-emitting diode lights, and the entire screen is made up of LED modules spliced together.
What is LCD?
LCD liquid crystal display is the abbreviation of Liquid Crystal Display. The structure of LCD is to place liquid crystals in two parallel pieces of glass, and then control the direction of crystal molecules to display the picture.
The working principle of LED display
The LED display is usually composed of the main controller, the scanning board, the driving power supply, the display control unit and the LED display box. block scan board.
Each scanning board is responsible for controlling several rows (columns) on the LED display screen, and the LED display signals on each row (column) are cascaded and transmitted through each display control unit of the row in a serial manner. Directly facing the LED display body. The work of the main controller is to convert the signal of the computer display card into the data and control signal format required by the LED display screen.
The function of the display control unit is similar to that of the image display screen, and is generally composed of a shift register latch with a grayscale control function. It’s just that the scale of the video LED display is very large, so integrated circuits with a larger integration scale will be used.
The function of the scanning switch is to link the previous and the next. On the one hand, it needs to accept the video signal brought by the main controller; The data of the cascade is transmitted to the next cascaded scan plate. The differences in space, time, sequence and other aspects of video signal and LED display data need to be coordinated through the scanning board.
How the LCD screen works
The composition of LCD liquid crystal screen mainly includes: backlight plate, upper and lower polarizers, liquid crystal, glass substrate, etc. This construction means that the LCD must have a container to carry it, so the LCD screen usually needs to be wrapped with a bezel.
The liquid crystal in the LCD screen is a relatively special substance. It has both the anisotropy of crystals and the fluidity of liquids. Most of the liquid crystal molecules are rod-shaped molecules, which are originally liquid crystals with different directions. Under the action of different voltages, they show different optical properties, as if Like metals in a magnetic field, liquid crystal molecules are also affected to a certain extent by the external electric field. Therefore, we only need to control the arrangement of the liquid crystal molecules to control the direction of light passing through the liquid crystal.
Since LCD is developed around liquid crystal, the display principle is inseparable from the credit of liquid crystal. Because the color filter is printed with color blocks of RGB three colors, when the light from the screen backlight passes through, the light first passes through the transparent The TFT thin film transistor substrate passes through the liquid crystal molecules, and then passes through the CF color filter. Under the influence of the different penetration rates of the liquid crystal molecules under each color block, the color blocks will emit different light and dark red, green and blue colors, which are mixed in Display the desired color together.
From the above principle introduction, we can already roughly understand the difference between the LED display and the LCD display. Next, we will expand and add more differences between the two.
The difference between LED display and LCD display
1. The light source is different
The LCD uses a CFL light source, and the LED display uses an LED light source.
2. Unlimited stitching
Because the LED display screen is composed of LED modules, the LED can be spliced with LED modules without limitation, while the LCD can only be spliced according to the corresponding size. compared to LEDs.
3. Seamless stitching
The LED display can be seamlessly and infinitely spliced. Although the LCD can be barely spliced together, there will be an irremovable border around it. In the control after splicing, there is not a lot of centralized control, so there are very few The LCD will be used for splicing.
4. Stereo effect
The LED display screen can produce a 3D effect on the flat display through a special splicing method, while the LCD can only be played on a flat surface, and no matter how spliced, it cannot form a 3D stereoscopic effect.
5. Alien structure
LED display has many strange shapes, in addition to the common cylindrical LED display, circular LED display, more complex spherical display, DJ display and Mobius ring display can be manufactured. This also proves The LED display has excellent plasticity.
The LCD can only be produced according to the specified shape, usually a square or a rectangle. After production, it cannot be additionally spliced into other shapes.
From the above content, we can find that the LED display has many advantages that LCD can’t match, but it does not mean that LCD has no merit. Like most small devices, LCD has always maintained an unshakable position, which also The side shows that LCD also has many advantages that LCD cannot match.
Even LED displays with very small pitches are still unable to be mass-produced and used on some small devices. On the one hand, it is the price, and on the other hand, there are technical limitations.