ACADEMICIAN WANG LIJUN INTERPRETS THE KEY TECHNOLOGIES AND TRENDS OF XR HEAD-MOUNTED DISPLAY

From November 30th to December 1st, the 2022 World Display Industry Conference, hosted by the People's Government of Sichuan Province and the Ministry of Industry and Information Technology, was held in Chengdu, Sichuan Province. Wang Lijun, foreign academician of the Russian Academy of Engineering and chairman of the AR/VR technical committee of the SID International Information Display Society (China), gave a speech on the frontier technology of XR head-mounted display and the development trend of the industry at the Chengdu-Chongqing New Display Integration Summit Forum on December 1. 

Since last year, the metaverse has become a hot topic in the industry and investment community. In fact, the concept and imagination of the metaverse was born on the eve of the Internet and has been staging different versions with the development of the Internet. Wang Lijun pointed out that the supporting technologies of the new generation of metaverse are 5G, artificial intelligence and XR head-mounted terminal display devices, and the development of these "core weapons" has created a good foundation for the realization of the entire metaverse. Among them, 5G technology solves the bandwidth problem; all virtual items and virtual scenes in the metaverse are three-dimensional and online, requiring low-latency interaction; 5G and fiber-to-the-home have created bandwidth conditions for the metaverse. At the same time, artificial intelligence has created very good conditions for the large-scale construction of three-dimensional objects, three-dimensional virtual scenes and images, digital virtual humans, etc. 

“Most importantly, the development of the head-mounted terminal will have a revolutionary impact on the field of the metaverse, and the development of the XR brings the metaverse into a new century”, Wang Lijun stressed in his speech. 

From the perspective of terminal development process, the core access terminal of Web1.0 stage is fixed, that is, personal computer; The Web2.0 stage is the mobile Internet, and the emergence of mobile smart phones has changed human production and lifestyle; In the next generation of immersive Internet Web 3.0 stage, XR head-mounted terminal is the next generation computing platform and also the access and interaction terminal of the metaverse. 

XR is an umbrella term for VR, AR, and MR. XR is a next-generation intelligent terminal and interactive system that expands human computing, perception and interaction capabilities, and will bring profound changes and major impacts to human economy, science and technology, culture, education, military and daily life. 

Wang Lijun analyzed the key technologies and trends of XR head-mounted display from the perspective of the display industry. Head-mounted display belongs to near-eye display, which has extremely high requirements for display performance: ultra-high resolution (PPI close to human eye 6000), high display contrast, high saturation and uniformity, high refresh rate, and low power consumption. In addition, head-mounted displays also have requirements for optical performance: large FOV, small size, light weight, low image distortion, high fidelity, and strong 3D immersion. From the performance of mainstream display technology, in terms of brightness, the third-generation display technology Micro LED will far exceed OLED and LCD to reach 100,000 nit; Micro LED has obvious advantage in contrast and response speed.

For VR micro display, it is mainly used by consumer, and its core is micro-display and optical system. At present, the fast LCD Fast LCD is mainly used, which can reach 2K or 4K resolution. In the future, silicon-based OLED may be used to provide higher image resolution and achieve smaller size. VR display optics mainly make the display thin and light through ultra-short focus or folding optics Pancake scheme. For example, Facebook's polarizing foldable optical path system allows VR glasses to be just 0.3 inches, while Huawei's foldable VR glasses can be the size of sunglasses by using an ultra-short focal optical module. 

For AR/MR display, the main application scenarios are in medical, industrial and other fields, and the core lies in micro-display and fusion optics. The progress of AR fusion optics has shifted from the original geometric optics to physical optics based on diffraction grating and integrated optical waveguide technology, and the advantage is that the micron-level device size can be achieved by semiconductor nanoimprint manufacturing process, which greatly improves the lightweight comfort of AR glasses. 

In terms of microdisplay technology, the traditional AR microdisplay mainly includes Liquid Crystal On Silicon (LCOS) and Digital Light Processing (DLP), while the current mainstream solutions are silicon-based OLED and Laser Beam Scanning (LBS). Micro LED is a major trend in the future, and its core parameters have obvious advantages: with ultra-high image resolution, luminance, contrast, refresh rate, ultra-high color fidelity, saturation and fFOV, as well as ultra-small size and power consumption. It is especially suitable for mobile intelligent XR devices. However, Wang Lijun also pointed out the key technical challenges faced by MicroLED microdisplays, mainly including single-chip wafer-level hybrid integration and full color.  

In addition, Wang Lijun also talked about the Light Field Display in his speech, which resolves the CA conflict of XR head-mounted displays. At present, the Light Field Display is more studied in academia, but there is still some space for progress before industrialization. 

In Wang Lijun's opinion, the XR head-mounted terminal will replace the mobile phone and become the primary metaverse intelligent interaction terminal for human beings. And this depends on the display industry practitioners continue to work and make efforts in the micro display drive, micro display chips. RayClouds is a high-tech enterprise focusing on optical measurement. We took the market as the guide, took scientific research as the core, and took innovation as the impetus to developed the V-20S virtual display optical analyzer, aiming to provide new optical measurement solutions for XR head-mounted display devices, create new visual sensory experiences, and deeply empower the industrialization process of cutting-edge technology products. 

Source: 中国电子报  Official Accounts