Scanning Line The Application of Time-division Scanning for LED screen If you were to use a traditional static scanning screen design, one square meter P16 LED display would need 768 LED driver ICs. But for a P4 LED display of the same size, you'd need a whopping 12,288 LED driver ICs!(How to calculate?) It's pretty much impossible to fit that many Semiconductor Components onto the same circuit board area. That's why we use something called time-division scanning, especially for high-density, small pixel pitch LED screen. Take a look at Figure below: it shows how this works. The LEDs light up one row at a time, starting from row 1 to row n. When it's time to light up row 1, transistor Q1 turns on, and the LED driver chip activates the LED based on the grayscale value. Meanwhile, transistors Q2 to Qn are turned off. Time-division Scanning Diagram The principle of time-division scanning in LED displays is similar to that of a cathode-ray tube (CRT). When we take a photo or record video of an LED display with a shutter speed higher than the refresh rate of the LED display, black lines appear on the resulting image, as shown in below Figure . These are referred to as Scanning Lines. LED screen shows Scanning Lines due to low Refresh Rate Below Figure is a 4-scan design as an example, it takes time "A" to complete the scanning of 4 rows. If we take a photo of this display with a shutter speed faster than time "A", we call it time "B", only rows 1 to 3 will be displayed, so a black line will appear every 4 rows on the screen. However, if we use a slower shutter speed than time "A", Let's say time "C", the LED screen will be able to complete the display of rows 1 to 4, and we will get a complete image. We call the refresh rate of this display 1/A Hz. Timing Diagram of an LED Scanning Screen Bright/Dark Lines 10 Times Refresh Rate As LED screens have become popular for conference backdrops, photographers often face issues. For instance, when capturing someone in front of an LED screen, the bright background can cause the person to appear too dark in photos. To counteract this, extra lighting is used on the subject, brightening the overall scene. However, when taking a picture, the camera adjusts by narrowing the aperture and shortening the shutter speed(S ≒ 200). Unfortunately, this leads to another problem: bright and dark lines appearing on the LED screen in the background, as seen in Figure below. Due to the excessive brightness of the LED screen, the photo of main character appears too dark. Figure: Bright Line and dark line in LED screen Why does the bright/dark line appear instead of solving the scanning line ? It will be explained with the following simulation schematic. A. Shooting a 1/16 scan LED screen with Refresh Rate of 960Hz by using 1/200 shutter speed: If LED screen "A" is designed for 1/16 scan with a refresh rate of 960Hz, when taking a photo of this LED screen with shutter speed of 1/200, it will get a similar result to Figure above↑: ...

Virtual pixel technology is an innovative method for digital displays that improves resolution without the need for additional physical pixels. In the past, enhancing the resolution of LED displays necessitated the inclusion of more physical pixels, resulting in higher production costs and increased power usage. However, virtual pixel technology bypasses this issue by employing a complex arrangement of LEDs to emulate a greater pixel density. Virtual Pixel Technology, also called dynamic pixel technology, is a technique that uses software algorithms to control the LED units in a display, so that each unit can contribute to the image of multiple pixels, thus increasing the resolution of the display by up to four times. It is different from the real pixel, where each unit corresponds to one pixel. For example, a conference all-in-one machine that uses Virtual Pixel Technology can achieve a near 4K resolution with the same number of LED units as a 2K resolution machine. This improves the display quality and uniformity, while reducing the cost. It is a good choice for most users who want a high-definition display. The Key of virtual pixel technology lies in its capacity to merge the color and brightness of nearby pixels to form a virtual pixel that looks smaller than it really is. Take a standard LED video wall with a 4mm pixel pitch for example. Virtual pixel technology can blend these pixels to mimic a smaller pitch, like 2mm. This effect is created by algorithms in the LED video wall's processing system that calculate the best values for each pixel, enabling it to reach a much higher resolution than what the physical pixels alone would indicate. A patented RGBG (Red, Green, Blue, Green) setup is crucial for these displays. By skillfully mixing these colors and adjusting the pixel layout, virtual pixel technology generates bright and crisp images. This technology offers a significant edge in the digital display industry by delivering excellent image quality without the extra costs and energy use linked to larger pixel counts. Virtual Pixels Real Pixels As is well known, each physical pixel is composed of R,G,B diode, while in the figure below, each B diode shared by 4 pixels.This is the underlying logic of virtual pixels. Benefit Energy Efficiency: Virtual pixel technology is very energy-saving, using up to 50% less electricity than traditional displays. This greatly cuts down on operating expenses, making it a wise option for extended use. Lower Operating Costs: Because it uses less energy, businesses can save significantly on their electric bills. Virtual pixel technology provides a budget-friendly option without sacrificing quality. Durability and Long Life: These displays are made with top-notch components to ensure they are sturdy and reliable. This means less frequent maintenance and fewer replacements, offering a lasting solution. Impressive Visual Effects: Virtual pixel technology produces stunning visuals with rich colors and clear images....

Definition of Color Gamut Color gamut refers to the range of all colors that a device (such as a monitor, printer, etc.) can reproduce. It reflects the device's capability in color representation, and different devices have varying color gamut ranges due to differences in technology and materials. Understanding color gamut is crucial for ensuring the accuracy of colors in images and videos, especially in fields like design, photography, and printing. In the real world, the colors of the visible spectrum in nature form the largest color gamut space, which includes all the colors that the human eye can see. To intuitively express the concept of color gamut, the CIE (International Commission on Illumination) has established a method for describing color gamut: the CIE-xy chromaticity diagram. Representation of Color Gamut CIE Chromaticity Diagram The CIE (International Commission on Illumination) has developed the CIE-xy chromaticity diagram to visually represent color gamut. In this coordinate system, the range of colors that various display devices can represent is shown as a triangular area formed by connecting three points representing RGB (Red, Green, Blue). The size and shape of this area reflect the types of colors that the device can display.The larger the area, the greater the color gamut range of the device. Color Gamut Standards sRGB: The most widely used standard, suitable for most computer and web applications, covering approximately 72% of the NTSC color gamut.The sRGB color gamut was born in 1996 and has been the most commonly used standard since the CRT(Cathode Ray Tube) era until now. Almost all monitors support sRGB nowadays, and it can easily handle web browsing, graphic work, daily office tasks, and more. Therefore, achieving 100% sRGB color gamut coverage is something that many better monitors can do now. However, the sRGB color space is only about one-third of the CIE 1931 XYZ color space, and sRGB has insufficient coverage for the green part of the color gamut. So, if an image originally has very rich greens (such as a picture of green leaves), it may lack expressiveness when viewed under sRGB. More importantly, sRGB is only suitable for self-luminous display screens to display "virtual" images and cannot be used on "physical" printed materials that rely on reflected light for color display. Therefore, to standardize the colors of printed materials, the CMYK color standard came into being. Adobe RGB: Launched by Adobe, it can express a broader range of greens and cyans, making it suitable for professional photography and design.The Adobe RGB color gamut was primarily developed to address the issue that the sRGB color gamut cannot cover the CMYK color gamut used in printing systems. Its main improvement is in the display of cyan-green tones, covering approximately 50% of the CIE 1931 XYZ color space. We can see their relationship in the color gamut diagram. Adobe RGB is a considerably large color gamut, and some high-end profes...

This Article was wroten by Tony Tong, the sales manager of Huasun, and initially published in Linkedin. Scan mode, also called Scan rate or scanning driving, refers to the number of LED pixels that can be connected to a single driver IC. Each pixel is connected to a pin on the driver IC on the PCB board. The number of drivers required on a PCB board design to illuminate the pixel pitch determines the scan type. Each LED pixel is connected to one pin of the driver IC on the PCB board. The more driver ICs we have on a PCB, the lower the scan type is. Most suppliers will have 1/2, 1/4, 1/8, 1/16 and 1/32 1/48 scan types. Scan and time multiplex are the same. The scan number is the number of drivers required on a PCB board design to light up the pixel pitch: The scan design is impacted directly by: Type/performances of the drive IC; Refresh rate; Grayscale; Pixel pitch; Static scanning: Static scanning is to implement “point-to-point” control from the output of the driver IC to the pixels. Dynamic scanning: Dynamic scanning is to implement “point-to-row” control from the output of the driver IC to the pixels. Each drive IC has 16 pins and can drive 16 LED chips maximum.Static drive mode means all the LEDs on the LED Tile can driven/light up by IC at once, as shown in the following image. 1/12 scan mode, means 1/12 LEDs on the LED Tile are driven/light up by IC at one time, and next time there are another 1/12 LEDs that are driven. 1/6 scan mode, means 1/6 LEDs on the LED Tile are driven/light up by IC at one time, and next time there are other 1/6 LEDs that are driven. Brightness: The higher the resolution and the higher the brightness are，the more drivers need to be used. This means we will have less space on the PCB. The higher the scan is, the lower the brightness. Theoretically, for the same LED screen, static scanning is twice as bright as 1/2 scanning, and 1/4 scanning is twice as bright as 1/8 scanning. And 1/5 scanning is twice the power consumption of 1/10 scanning.However if brightness is not an absolute requirement, there are ways to lower the brightness by experimenting with the software. A high scan drive can reduce brightness of the LED screen and in most cases suppliers can use higher scans on higher resolution screens to compensate for brightness to be more cost effective.Because the number of required driver IC has decreased. Most high scanning Drives can be used on indoor LED screens as high performance of the screen is not an absolute requirement. Because brightness is not an issue for indoor LED screen and you won't have to compensate when there is not enough space for the PCB. Therefore, it's very important to choose a reasonable scan mode for the LED screen.It needs to be based on the brightness, power consumption, refresh rate and cost – not simply the higher the better. For Example： Taking a 1/45 scan P1.875 design with the LED and driver IC on the same side as an example: LED Tile size:300×168.75mm. pixel resolution: 160×90=1...

This Article was wroten by Tony Tong, the sales manager of Huasun, and initially published in Linkedin. Problem 1: Ghosting Phenomenon This issue with scanning indoor led screens is the ghosting phenomenon, which is mainly caused by the charging and discharging of parasitic capacitance on the PCB during the operation of switching rows and columns on the display screen. This results in LEDs that should not be lit up being illuminated, especially when applied to oblique scanning, where the ghosting problem is more pronounced. Ghosting issues on LED scanning screens have both upward and downward ghosting effects. Problem 2: Colorshift at Low Grayscale The test pattern used at picture 2 consists of a low grayscale white pattern. When the pre-charging function is turned on, we can see that the module appears reddish. Picture on the right shows use of some better chipset to eliminate color shift when pre-charging has just been turned on. Problem 3: Non-uniformity at Low Grayscale Non-uniformity is particularly noticeable under low grayscale conditions, which places very strict requirements on the uniformity of driver ICs. Pre-charging is performed to raise the voltage levels in the rows to eliminate downward ghosting effects. However, this method can lead to issues of non-uniformity in certain areas. This effect is more visible to the naked eye when displayed with low grayscale images. Unevenness in medium and high grayscale images may result from differences in PCB layout and varying voltage levels due to discrepancies between driver ICs. A low grayscale monochrome test pattern was utilized in Figures 1 and 2. There will be deviation between LEDs in the same patch. The sum of such characteristic deviation is the cause of the blurry screen effect. As shown in Figure 3 and 4, the same source materials are displayed in full screen. The brightness of individual pixels differs and is distributed randomly as shown in Figure 3, and does not show significant improvement even under increased brightness. Brightness calibration is an effective way to fix the blurry screen effect. However, the cost of brightness calibration is high and recalibration will be required for aged LEDs. In other words, recalibration will be needed at regular intervals, creating higher maintenance costs. Some better IC utilizes built-in brightness equalization to create more even, smooth screen brightness as shown in Figure 4. Problem 4: Dim Line at The First Scanline The way a scan type display works is to light up LEDs line by line, You will notice that the first scan line in the upper and middle parts of the picture are abnormally dark; This phenomenon is known as the dim line.If LEDs in a frame are off for longer than they are conducting, parasitic capacitance in the PCB module will lead to increased column voltage. In particular, the column voltage when Row 1 is scanned and conducting will be higher than the column voltages when the other rows are scanned. Problem 5: Gradient Dim L...

This Article was wroten by Tony Tong, the sales manager of Huasun, and initially published in Linkedin. View Distance The image perception is influenced by the distance between the viewer and the LED screen. The ideal viewing distance is 1x ~1.5x the pixel pitch in meters. So in a 12 mm pixel pitch screen it is around 12 meters. At this distance the human eye (or brain) no longer sees individual pixels but the whole picture. Of course you can get closer (and certainly further away) watching the screen. Closer to the screen the pixels will become increasingly evident, but the image will no long remain acceptable. The viewing angles for an LED displays are measured horizontally and vertically, and indicate over what range images on the LED screen are fully visible without the screen displaying a negative image.The viewing angle of a LED display represents the limit of its optimal picture quality. Sit at a position at a wider angle than that of its viewing angle and you will experience worse picture. The LED industry defines viewing angle as the full angle at which brightness is half of the brightness from dead center. (The view angle of a screen is by convention the angle within which the brightness of a display is equal to the 50% of the frontal luminosity.).More scientifically, if ø (angle theta) is the angle from off center (0°) where the LED’s brightness is half, then 2ø is defined as the full viewing angle. For example, a LED screen with 5000 NIT frontal brightness has a visibility angle equal to the angle by which the brightness is reduced to 2500 NIT. This visibility angle can vary depending on the LED and the technical features of the display. In conclusion, it can be stated that loss of brightness under viewing angle start with radiation characteristics of individual LEDs. In most cases radiation characteristics of LEDs show 50% brightness level at about 60°. If the viewing angle of the LED screen becomes lower, the LED screen brightness will be higher, or vice versa. If the contrast ratio between LED screen's brightness and environmental brightness is higher, the led screens’ showing performance will be more colorful. But a too high brightness will consume a lot of energy and create high heat. For that the LED's brightness decreases much faster, and of course, its lifespan will become shorter. For more information, welcome to contact us