On-board transparent display coming: a brief analysis of 6 popular schemes

In recent years, with the outbreak of metauniverse, enhanced display and other industries, the Oems have proposed in-car interaction, entertainment, office, navigation and other needs, but the traditional display is opaque, can not be used in the limited space in the car, the body of nearly 60% of the area of the glass, into a transparent display is the best solution. From the perspective of various technologies at various exhibitions in recent years, transparent display technology can be said to be a new generation of human-computer interaction HMI solution that combines science fiction and reality.

The transparent window display of the BMW DEE concept car, the projection solution provided by Lightpeak Technology

The transparent display not only includes the popular HUD head-up display, but also includes the window display, instrument aerial imaging/media-free instrument, and so on. These display technologies include DLP projection, OLED or MicroLED solutions, holographic technology, and more. This article will take a brief inventory of the six popular transparent display solutions for you:

1, transparent LCD display

When it comes to LCD transparent screen, it is not a new technology that has appeared for a long time, and the most well-known application is the transparent box display cabinet.

The LCD transparent screen is actually an incomplete LCD screen, an application mode invented by removing the backlight unit behind the normal screen, that is, the object displayed is placed between the backlight unit and the display layer. The LCD transparent screen needs the box to be used as the backlight unit, otherwise it cannot be displayed normally. The LCD transparent screen does not have the characteristics of self-illumination, which needs a backlight as a supplement, and is not transparent in the non-powered state and is displayed as black.

On December 20, 2022, Japan JDI Company showed its latest transparent LCD display product - "Rælclear" display, the 20.8-inch product light transmission rate reached 84%, known as the world's most transparent LCD screen.

Without displaying the contents, it looks almost the same as a piece of glass. After lighting, this "glass" will be incarnated as a display with a resolution of 1280*720P, with 120Hz high brush, 300cd/m ² brightness, and support 409.6 billion colors, which can meet the display needs of window booths, medical check-ups and so on. JDI said the Rælclear LCD display is expected to be on display during CES2023 and will be available in full volume production in autumn 2023.

2. Transparent OLED

Transparent OLED display is the use of self-luminous transparent organic OLED screen, the material is OLED. When the screen is closed, it presents the visual texture of transparent glass and harmonizes with the environment; The futuristic design can also give users a stunning visual experience.

Contrast between ordinary OLED sub-pixel and transparent OLED sub-pixel

In 2010, Samsung introduced a concept laptop with a transparent OLED screen, you can see the Windows system running on the screen, and do a good job of icon and text clarity.

Samsung's transparent laptop on display at CES 2010. Image from: Wired

The panel used in the Xiaomi transparent TV is also provided by LG. The "cool" of transparent TV is also the main reason why it is desirable. But in terms of practicality, televisions may not be the best category for transparent displays.

Samsung's fully transparent OLED display in 2016

Boe in the world's first 49-inch bar transparent OLED smart window at 2023SID, using white OLED, transmission rate of up to 40%, display color uniform, clear picture, car interior and road driving scene combination of virtual and real, rich travel experience.

Boe global debut 49 inch bar transparent OLED smart window

3, LED transparent display: Mini LED/Micro LED

In recent years, with the expansion of market demand for LED display industry and the continuous expansion of application fields, LED display products have shown a diversified development trend. The LED transparent screen as a rising star in the LED display industry, with its light and thin, no steel frame structure, easy installation and maintenance, good permeability and other advantages, in the glass curtain wall, stage display, outdoor advertising and new retail and other fields of application like a fish in water, is eye-catching attitude into our vision.

Transparent MicroLED display technology can make the windshield and window equal display; Flexible Micro LED makes the interior design more distinctive; Microleds with high brightness and contrast are still visible even in the sun. · LED's high brightness, high contrast, bendability, transparency and excellent reliability are the ultimate solution for providing all-round display applications in automobiles.

Nai Chuang 11.6 "24:9 automotive MicroLED display, can be used as the car center console

Au 60 "Micro LED transparent window display

It can be adjusted and extended to different fields according to demand, including car side Windows or family porch, smart window, commercial display, etc., to provide rich information and entertainment content.

Tenma's 9.38-inch transparent Micro-LED

Tianma microelectronic extreme display micro led

Au Transparent Micro LED

Fine light display Mini LED full color transparent display

4, thin film electroluminescent display

DEMO 1-5 P FOX Transparent display

How it Works:

LUMINEQ® thin film electroluminescence (TFEL) displays include solid glass panels, electronic control circuits, and power supplies. The thin-film electroluminescent glass panel is the core of the component, which consists of a luminous phosphorus layer sandwiched between a transparent dielectric layer and a transverse and longitudinal electrode matrix.

Our rugged display contains one layer of transparent electrodes and another layer of non-transparent electrodes. When both electrode layers are transparent, the display becomes transparent, and the transparency exceeds 80%.

The circuit board containing the drive and control electronics is connected directly to the back of the glass panel. By applying a voltage to the horizontal and longitudinal electrodes, the pixels on the display can be lit up, so that the intersection areas are illuminated.

5, reflection imaging: suspension instrument/air imaging/holographic assistant

The suspension instrument |, with its strong science fiction sense and cool appearance, frequently appears in major auto shows and various concept car design schemes. This year, with the continuous efforts of major manufacturers in the field of vehicle display, this concept product has been gradually applied to actual cases.

Interactive aerial imaging technology has revolutionized the traditional display and human-computer interaction methods. Through the core product of negative refraction flat lens, the principle of light field reconstruction is applied to reconverge divergent light in the air, thus forming a real image that does not need to be carried by media. Combined with interactive control technology, direct interaction between human and the real image in the air can be realized.

Dongchao Technology's non-contact intelligent vehicle application solution includes five aerial imaging technologies: air instrument, car machine wizard, passenger holographic entertainment screen, rear central armrest, and front seat back, making human-vehicle interaction more intelligent and ecological.

East super technology aerial imaging

Prism holographic AID-Aerial Intelligent Display system, HUD integration application, combined with innovative UI/UX, software applications and multi-modal interaction, to build a humanized and intelligent driving space, providing drivers with a new driving experience.

Airborne mediumless physical imaging, high-tech sense, integrated core instrument information, replacing the traditional physical car dashboard. Innovative visual UI/UX design to provide a rich and comprehensive holographic 3D display to meet the intelligent needs of future travel.

6. Projection display

The projection display has many innovative applications in the vehicle display, such as providing driving assistance, human-computer interaction experience and entertainment and other functions, including the roof canopy, window transparent display, entertainment screen, AR-HUD, intelligent surface, intelligent laser headlights, etc., the market space for vehicle display is broad.

Figure HUD schematic from Japan Seiji official website

Taking AR-HUD as an example, the core image of its projection scheme is in the optical part,  amplified by a free-form mirror, and then projected onto the road,  which can bring a more intuitive driving experience to the driver.

Other projection displays such as side window projection, its principle is actually similar to AR-HUD, are projected onto the glass through the optical machine, but the difference is that the side window projection does not pass through the mirror and free-form mirror to enlarge the light path.

BMW side window projection concept, courtesy of Light Peak

Holographic film

Holographic projection is a hot technical solution at present. It is through the holographic film the projection display screen becomes 3D three-dimensional, so as to be more realistic. Holographic projection lighting not only allows others to notice the car, but also conveys safety information through the display, such as displaying "stop", thus adding an additional safety element to the car.

Covestro Bayfol® HX photosensitive polymer films and other holographic projection films

Thin film is widely used in many fields, from automobile intelligent cabin, 5G mobile phone shell to identity document creation, a variety of new material film products and application technologies emerge in endlessly. For example, as a world-renowned material supplier, Covestro produces holographic projection films such as Bayfol® HX photosensitive polymer films, which have great potential to push automotive lighting to a new level.