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 indoor scanning 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 Lines...

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

This Article was wroten by Tony Tong, the sales manager of Huasun, and initially published in Linkedin. LED displays promise to change the way movie and television productions are created, but the effects are only as good as the video walls on which they’re shown. Those displays are constantly improving. Just a few decades ago the pixel pitch, or the distance between individual pixels in an LED display, was in the range of 12 mm, making them suitable primarily for viewing from a distance. Today, the pixel pitch of some displays is in the range of .6 mm or smaller, making them comparable in resolution to an LCD display. Although that shrinking pixel pitch has greatly improved the resolution of the displays it does create challenges that need to be overcome to make them suitable for video applications. Concerns that need to be addressed when using LED displays in video productions include: Brightness Adjustable screen brightness For different scenarios, the brightness of screen is needed to adjust to meet requirements. Refresh rate Refresh rate at high brightness – According to the “10 times refresh” theory, the refresh rate for LED displays needs to be more than 10 times the camera shutter speed for images taken by the camera to be free of lines and defects. A typical camera has a shutter speed of about 1/200 second, so the refresh rate of an LED display in a broadcast application needs to be greater than 2,000Hz or bright lines will appear in the image. Most fine-pitch LED displays today use PWM-based driver chips, which have the characteristics that the refresh rate at low-grayscale levels is lower than that at high-grayscale levels. As a result, when showing a low-grayscale image on the LED screen black streaks appear on the picture taken by the camera, greatly affecting the visual experience. Grayscale The loss and discontinuity of pixel data at low grayscale levels greatly reduces the smoothness of images, causing them to appear unclear to viewers. There are two causes of this problem. The first is that the grayscale data of the video source is compressed. This leads to a loss of a certain amount of grayscale and is likely to cause blocky images. The second is that the grayscale output bit number of the LED display is too low. Therefore, the jump span of each level at low grayscale is too large, thereby causing discontinuity. HDR If the LED display has a higher grayscale output, such as 16-bits, it can decrease discontinuity problems and lead to a better visual performance. Viewers can see more details, especially under low brightness conditions. In addition, when the video source is HDR, an LED displays would perform better with 16-bit grayscale output and a higher refresh rate. This kind of opulent image quality will bring a photorealistic performance making it well suited for movie backdrop use. Contrast Insufficient contrast causes a loss of image detail and results in images without multiple layers, similar to a painting without depth an...

SMD, COB, and GOB are the packaging technologies for LED. This article was written by Tony Tong of Huasuny, and first published in linkedin. 1. What is SMD LED? SMD is short for Surface-Mounted Device. SMD LEDs are a type of LED technology where the LED chips are mounted directly onto a printed circuit board (PCB). The design of an SMD LED typically consists of three primary components: the LED chip, a phosphor coating, and a small reflective cavity. 2. What is COB LED? COB is short for Chip-on-Board. This type of LED technology involves mounting multiple LED chips directly onto a single substrate, creating a unified light-emitting surface. 3. What is GOB LED? GOB is short for Glue-On-Board. GOB LEDs are a type of LED technology that uses transparent glue to cover the entire surface of the SMD LED display modules. GOB is an upgraded version of SMD. ROUND 1: Reliability 1. Artificial knocks and collisions: In actual applications, it is difficult for the screen to avoid external force collisions during transportation and handling, so anti-collision performance has always been a major consideration for manufacturers. As high-protection display module technology, the protection level of COB and I also varies. COB directly solders the chip to the circuit board and then fills it with glue in one piece; while I first encapsulate the chip in the lamp bead, then solder it to the circuit board, and finally fill it with glue in one piece. Compared with COB, there is an extra layer of packaging protection, and the anti-collision ability is better. 2. External forces of the natural environment: Using epoxy resin with ultra-high transparency and super thermal conductivity as the glue-filling material, I can achieve true moisture-proof, salt spray-proof, and dust-proof to be suitable for more harsh environments. ROUND 2: Display effect COB has risks in separating wavelengths and colors and picking up chips on the board, making it difficult to obtain perfect color uniformity for the entire display. Before I perform special gluing, I will manufacture and test the module in the traditional way consistent with ordinary modules, avoiding color difference, moiré, and other defects in light and color separation and obtaining good color uniformity. We regard a single LED pixel/module as a rose. ROUND 3: Cost Theoretically, the manufacturing cost will be lower because the material composition process is less and the required materials are less. However, since COB adopts whole-board packaging, it must be passed once in production to ensure that there are no bad pixels before packaging; the smaller the point spacing and the higher the precision, the lower the product yield. It is understood that the current COB normal product shipment rate is less than 70%, which means that the overall manufacturing cost will also have to share an increase of about 30% of hidden costs, and the actual expenditure is much higher than expected. As an extension of SMD technology, I can i...