Glass Curtain Wall LED Display Solution: Six Factors to Consider

Many high-rise buildings in cities have glass curtain wall structures, which are excellent outdoor advertising carriers. Through LED transparent screen technology, buildings can be transformed into three-dimensional optoelectronic advertising carriers, which have become popular both domestically and internationally in recent years.

When designing a glass curtain wall LED display screen, important factors such as display content, space conditions, screen size, and pixels should be considered. At the same time, it is necessary to ensure that the production process, technical indicators, and other factors are suitable for the actual application needs of the glass curtain wall. Combined with the project cost, a reasonable design should be carried out.

1、 Point Spacing

The dot pitch is the distance between the centers of two adjacent LED beads, measured in millimeters. The visual graininess mainly comes from the human eye having a certain resolution. When two points are viewed at a certain distance, the human eye will not be able to distinguish them when they are close to each other to a certain extent. In the past two years, with the improvement of LED transparent screen manufacturing technology, the resolution of glass curtain wall LED display screens has been continuously improved. The design of glass curtain wall displays has been upgraded from initially selecting the smallest point spacing specification scheme to selecting the appropriate point spacing specification scheme.

So, how to choose the appropriate point spacing specification scheme?

1. Dot spacing is an important basis for LED curtain wall screen models and also determines the final display effect of the screen. The smaller the model, the smaller the dot spacing, and the higher the pixel density, the more suitable it is for playing high-definition content.

2. The choice between point spacing and transparency is a dilemma, with smaller point spacing generally resulting in lower transparency. This is because the smaller the dot pitch, the higher the pixel density, and the more LED beads are arranged per unit area, which inevitably loses some transparency. High transparency is precisely the biggest advantage of LED transparent screens, and the cost of improving transparency is the expansion of dot pitch, which affects the clarity and display effect of its image.

3. Viewing distance is an important criterion for choosing a model. The farther the viewing distance, the larger the screen area, making it suitable for selecting larger products; The closer the viewing distance, the smaller the screen area, so choose a smaller model product.

But with the advancement of technology, the dot spacing and transparency can be further improved to achieve a large ideal balance point, such as a transparency of over 90% and a pixel density of 3-6mm spacing.

2、 Packaging Technology

One factor that determines the quality of LED is the main materials, such as box material, chip, LED beads, power supply, etc. Another factor is the packaging process. Pixel packaging technology is related to the color saturation, viewing angle, display effect, production cost, quality stability, etc. of the entire transparent screen. Transparent LED curtain wall packaging technology mainly uses surface mount SMD mode. Surface mount refers to the process of attaching packaged light-emitting tubes to a circuit board and then processing them into a screen body through integrated circuit soldering technology. It has good heat dissipation and uniform color, and the entire screen can be maintained from the front, greatly reducing maintenance costs and difficulties; At the same time, filling metal compounds during the packaging process results in good color mixing and soft luminescence.

3、 LED Control Part

The LED control part is the core component that determines the display effect, and the control circuit is equipped with a high-performance single-chip microcontroller chip. The controller sends control signals and data to the LED driver chip through an internal control program. Upon receiving the signals, the LED driver chip generates corresponding actions to achieve individual control of each red, green, and blue LED emitting chip.

3.1 Drive System

The function of the LED driver is to receive color data and drive the LED transparent screen to display the brightness value represented by the data. There are usually three methods: constant current, voltage stabilization, and constant voltage constant current.

The output current of the constant current drive circuit is constant, and the output DC voltage varies with the change of load resistance. The entire circuit is not afraid of load short circuit, but it is strictly prohibited for the load to completely open circuit. The voltage regulator circuit outputs a fixed voltage, and the output current varies with the increase or decrease of the load. The entire circuit is not afraid of open circuit of the load, but it is strictly prohibited for the load to be completely short circuited. The most ideal driving circuit is to first maintain a constant voltage and then maintain a constant current. It not only detects the LED current but also controls the LED voltage, which is beneficial for improving the lifespan of the LED and reducing power consumption. It is generally used in high-end LED products.

3.2 Control System

The display effect of LED depends on the magnitude and time of the current and voltage passing through it, so the control system mainly controls the power output of LED. At present, LED power supplies designed with PWM (Pulse Modulation) control method have a conversion efficiency of up to 80% to 90%, and the output voltage or current is very stable, making them highly reliable power supplies.

PWM can control the time ratio of LED on and off, by dividing the time ratio into several levels, so that the LED displays the corresponding number of gray levels (gray levels). The product of the grayscale levels of the three primary colors is the theoretical number of colors that can be reproduced on a display screen, usually 256 levels. When the number of colors reaches 16.7M, 24 bit true color information can be displayed.

The frequency of PWM is generally greater than 100Hz, otherwise there will be flickering and scanning lines during viewing. Nowadays, large screens with a grayscale level of 10 bits typically have a refresh rate of 800-1000 Hz, while transparent screens in the LED industry typically have a refresh rate of 1920Hz or higher.

4、 Display Requirements

1) Unit modular planning, with no seams on the entire screen. When playing a video, the image will not be stitched or cut, which will affect the visual viewing effect.

2) The overall color and brightness consistency and uniformity of the screen can be checked point by point. Completely avoiding phenomena such as color difference, dark corners, dark edges, and "patching".

3) Due to the significant impact of outdoor lighting, the brightness requirement for LED curtain wall screens is above 4000cd/┫. And it supports intelligent brightness adjustment, which can adjust the brightness according to the changes in brightness and darkness of the surrounding environment, making the picture more comfortable and details appear perfectly.

4) Wide viewing angle, supporting horizontal 140 °/vertical 140 ° large viewing angle display, satisfying different viewing angles and covering more audience groups.

5、 Installation Method

On the premise of avoiding damaging the appearance and structure of the glass curtain wall, the installation method may also vary depending on the actual situation on site:

Full hidden frame: It is to fix the LED transparent screen on the aluminum alloy frame, with the upper and lower horizontal beams corresponding to the aluminum alloy frame, and the two sides of the glass corresponding to the left and right vertical bars of the aluminum alloy frame.

Semi hidden frame: Due to the fact that both vertical and horizontal hidden glass curtain walls are called semi hidden frame glass curtain walls, there are two installation methods for this type of semi hidden frame curtain wall glass. Vertical visible and horizontal hidden refers to fixing the glass installation in the groove, and then reinforcing it with glass glue on the left, right, and horizontal sides; The vertical hidden and horizontal visible curtain wall glass should be placed in the aluminum alloy inlay groove of the horizontal bar, and then covered with a pressure plate outside the glass, and the aluminum alloy vertical bar should be hidden behind the glass.

Clear frame: Regardless of whether the frame and glass frame are made of special aluminum alloy profiles or steel frame, the aluminum alloy frame in the entire curtain wall will be exposed to the outside.

Hanging bracket type: This is an installation method of welding columns and stainless steel pendants, which connects the four claws of the pendants to the glass holes of the curtain wall, with one hole corresponding to one claw. It can also be said that first drill a hole in each corner of the glass, and then fix the glass on the four claws of the stainless steel pendant.

Frameless: The glass on the frameless curtain wall can also be called structural glass. This kind of curtain wall is mostly used on the first floor of a building, similar to the french window of a building. Its glass is installed in the form of hoisting, which is a method of hanging the glass from above using hooks or special profiles with symmetrical intervals. The operation steps are to first use a special profile hook to fix it on the main frame of the channel steel, and then hang and hoist the channel steel at the bottom of the plate or under the beam. To strengthen the rigidity of the glass, support frames or crossbars can be added to the top and bottom of the glass.

6、 Exterior Structure

For example, the glass curtain wall structure of a building, which is not a conventional flat shape, such as curved, fan-shaped, triangular, circular and other structures, requires special design requirements. Make the LED curtain wall screen better adapt to the overall structure and usage requirements of the environment.

Due to their different appearances and structures, higher requirements are placed on research and development capabilities and production processes. If the manufacturer's technology is not up to par, the assembled LED screen will have many problems such as uneven appearance due to large seam gaps and discontinuous splicing surfaces, which will affect the viewing effect and destroy the overall design aesthetics. More importantly, the design of the circuit and structure of LED irregular screens is more complex, which puts high demands on the research and development capabilities of manufacturers.