Macroblock

This is an extract translation of an article published by the Hangjianet on February 25, 2021.
Visit https://mp.weixin.qq.com/s/Bbri_Oq0UXlS4H3LB-LY6g for the original article.

3D display technology has progressed rapidly since Avatar premiered in 2009. The applications soon spread from cinemas to TV and LED displays, driving the LED display industry. However, the development then slowed down till 2020 when numerous 3D display installations made headway. 

As the explosively popular outdoor 3D display attracts the attention of the industry and the general public once again, every link of the ecosystem focuses on the differences in hardware and software as well as special demand between outdoor glasses-free 3D LED displays and regular LED displays. At the same time, building owners are beginning to inquire Hangjianet about 3D display technology, products and pricing.

To get to the bottom of this, Hangjianet interviewed 6 top LED display manufacturers including Leyard, Unilumin, LianTronics, Cedar Electronics, Ledman Optoelectronic and Aoto Electronics as well as key light source, driver and control system suppliers such as NationStar’s RGB super business unit, Macroblock and NovaStar.

Q1: What is glasses-free 3D LED display? What are the criteria for rating them?
Aoto：There are two types of 3D displays: passive and active. With traditional glasses-free 3D display, the parallax between what the left and the right eyes see creates the 3D effect. Many popular glasses-free displays combine display installation scenario with creative content creation to offer an immersive experience so they are not glasses-free 3D displays in the traditional sense. We think the 3D effect of existing glasses-free 3D display need to be judged by the integration of display performance, installation scenario and creative contents.
Leyard: Glasses-free 3D display first appeared as an LCD technology that used lenticular or slits to create multiple viewpoints, ensuring viewers will perceive the 3D effect without glasses regardless of their viewing angle thanks to the parallax between left and right eyes. We announced glasses-free LED displays based on fine pitch technology quite some time ago and used in many exhibitions. To be more precise, the popular glasses-free 3D displays should be called “displays capable of creating 3D effect without glasses.” They are really 2D LED displays combined with 2D videos created specifically for the glasses-free 3D effect. The explosive popularity really shows that the result requires a perfect marriage of hardware and contents.     
Ledman: Glasses-free 3D means you don’t need glasses to perceive the space and stereoscopic effect. The result can be judged based on the viewing distance and the content. The pitch of the display determines the viewing angle and the viewing distance given the varying installation scenarios. As the resolution of the content improves, more contents can be shown. Furthermore, the design of the content is critical. Videos designed specifically for display with glasses-free parallax will be more immersive.
NationStar: Most big LED displays create glasses-free 3D effect by leveraging the distance, size, shadow and perspective of the subjects for 3D effect with 2D screens. Using the background shadow as the static 3D reference line, the incredible 3D wave on the façade of SMTOWN Coex Artium looks like it’s going to break out of the screen. With the display creating a 90-degree fold of the image, the left side of the display shows the left view of the image while the right side of the display shows the front view. As viewers at the corner sees the side and the front of the object at the same time, the 3D effect looks very real. The breathtaking effect is backed by tremendous technical refinement and powerful products.  
Macroblock: Glasses-free 3D display adds optics to a display to create parallax between left and right eyes so that viewers see 3D images without wearing glasses or other devices. There are two types of 3D display technology. One is parallax barrier, which creates the effect with transparent and opaque strips to control the direction of the light. The other is lenticular lens, which creates the parallax effect by leveraging the focusing and refractive properties of lenticular lens to change the direction of the light and split the light. They share a common weakness as resolution is halved, which means twice as many LEDs are needed. Parallax barrier technology also reduces the brightness of the display. As a result, fine pitch LED displays are ideal for outdoor glasses-free 3D display media.     

Q2: What makes outdoor 3D LED displays different/ difficult from regular LED displays in terms of hardware and software?
Ledman: A couple of things make it difficult.
1) Regular displays are 2D. 2D and 3D contents don’t look 3D on them. Now we use displays mounted at a 90° degree to create a non-2D display surface. Some of the curved components (PCB, module, case, etc.) have to be customized.
2) The contents are more expensive since they are customized for the display resolution.
Macroblock: To achieve optimal results, glasses-free LED displays need software that supports high resolution and high color depth video encoding and works well with screens of nontraditional shape such as polygonal or curved. As far as hardware is concerned, glasses-free 3D LED displays put special emphasis on fine details so they are more demanding when it comes to grayscale, refresh rate and frame rate.  
Aoto: Comparing to traditional LED displays, glasses-free 3D displays are demanding in terms of hardware and software with more stringent specifications and design requirements. This is most evident in 1) content design and creativity for parallax; 2) blending display color and ambient light; and 3) blending LED display installation structure and surrounding. 
Lian Tronics: 
1) Hardware: Relative to traditional products, glasses-free 3D LED displays put special emphasis on high refresh rate, high grayscale, high dynamic contrast ratio and smooth transition for curved surface/corner. In addition, content server has to be connected to a high-end graphical workstation with multiple display synchronization card;
2）Software: Professional decoder is a must. The decoder has to support material mirroring and correction for heterogeneous display media in addition to decoding for high streaming rate;
3）Contents: There are also requirements for contents. The selection of front view has to be based on the perspective relationship of the display shape for the right 3D structure. Custom resolution is also a must for the best results. HAP format is recommended;
4）Technical progress: We saw the evolution of hardware and software in addition to improved material quality in recent years. Videos are now created and refined to premium levels. Moreover, artistic structures fuel imagination since they are no longer limited to the traditional flat design.
Leyard: To achieve better results, display hardware needs improved contrast ratio and high dynamic range (HDR), which are the most important criteria. For example, our micro LED line has much improved contrast ratio for small pitch products as it supports the most high-end HDR specifications and higher dynamic range, maximining details in the darkest and the brightness areas. The viewing experience will be immersive as people only see the image but not the display. 

Table 1. Hardware and software differences between regular displays and 3D displays (Source: Hangjianet)


Q3: What new requirements does each link of the 3D LED display ecosystem have? 
Ledman: Mostly brightness and driver. The majority of existing glasses-free 3D displays use SMD outdoor P2.5-P8 specifications. As the environment is relatively bright (especially at noon), the LED display has to be brighter than 6,000 nits for proper viewing. Since the brightness needs to be reduced to reflect the environment at night, the choice of driver is pivotal. Regular ICs adjust brightness at the expense of grayscale, affecting performance. To avoid the pitfall, we insist on current-gain PWM driver for glasses-free 3D displays to ensure the best picture quality and enough refresh rate for pictures taken by viewers.      
NationStar: To realize amazing 3D effect, we do need display hardware with high resolution, high dynamic contract ratio, smooth curve/ corner transition and better video materials, which require stable display components with superior color reproduction.
Aoto: As a LED display manufacturer, we see the indicators and differentiation manifest mostly in the core control system for LED displays and the design of LED display offerings. The biggest challenges are about the results and the performance of LED displays, including IC, LED display control system, media software and creative content design.  
Leyard: From our perspective, it’s about the improvement of manufacturing technology and higher contrast ratio. Patented driver can achieve high-end HDR results.
Macroblock: As far as LED driver is concerned, outdoor 3D LED display creates a new hotpot that attracts eyeballs and photography. Therefore, the hardware should support high gray and excellent minimum gray, high refresh rate of 3,840Hz, high dynamic range (HDR) and low power drivers for realistic and amazing 3D effect.
NovaStar: We provide core display control systems for LED displays that are pivotal to outdoor glasses-free 3D installations. LED displays need to meet more stringent requirements for better outdoor glasses-free 3D performances. The control system has to support higher resolution and more highly integrated technology to enhance picture quality.  

Table 2. Outdoor 3D LED display requirements: light source, driver, control system and screen (Source: Hangjianet)


Q5: What are your plans, technology and progress with outdoor 3D displays?
Macroblock: As outdoor display emphasizes display quality and brightness, Macroblock launched MIB5251, an IC designed specifically for the application. It supports up to 8 scans and can drive high current outputs. Precise control of drive current and optimized display performance enables excellent picture quality. Furthermore, users can lower the power of outdoor displays by reducing the supply voltage. They are all part of the 6 New Basics advocated by Macroblock. Macroblock products are known for their superior quality and excellent reliability, which makes them the first choice for clients who need outdoor displays in challenging environments.

Q6: Looking forward to 2021, how will outdoor glasses-free 3D LED display evolve? 
Macroblock: Outdoor glasses-free 3D LED displays are the ultimate marriage of display technology and art installation as it provides new visual experiences while attracts audience attentions and creates topics on social media. Future LED displays will come in fine pitches, higher resolution and more shapes as they blend with public arts and even with natural surroundings.