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Spring 2025 Vol. 24

Design

JANUS: A next-generation transparent display enabling collaboration and privacy

July 27, 2023 hit 129

JANUS: A next-generation transparent display enabling collaboration and privacy

JANUS uses the principle of Persistence of Vision (POV) to achieve highly preserved transparency with high independence of content on each side in a transparent display.

Article | Spring 2015

The transparent display has already become an icon of the future thanks to numerous science fiction movies. In such movies, the display’s transparency provides us with compelling visual openness. However, if every monitor in your office suddenly became see-through, you would find yourself facing practical problems immediately after you start working with one of them. When writing an e-mail, everything you do would be exposed to people behind the screen. Loss of privacy is an inevitable drawback in transparent displays because people would share access to the screen from both sides. More precisely, laterally inversed images would be visible from the other side.

Professor Woohun Lee’s Design Media Lab suggested the concept of JANUS. JANUS is a “double-faced” transparent display that can preserve both privacy and transparency. Interestingly, POV displays are intrinsically see-through, and their images can only be seen from the side where the LEDs are laid out. To implement the design concept, they devised a new POV display that has arrays of LEDs on both sides of a PCB blade. Mounted with infrared touch sensor frames, JANUS is a double-sided POV display with a touch interaction feature.

JANUS has two separate graphic layers with directivity so that collocated face-to-face interactions through a transparent display can be even richer. Two users on each side can share an identical image on the screen and they can also see totally different images on the same spot. In the former case, users can collaborate while viewing the same image, and in the latter case, they can work on independent tasks on same part of the screen. People would be able to control the visibility of visual contents on the transparent screen to the other side at their convenience.

If a user finds an interesting photo on the internet, he or she can push the image and transfer it to a user on the other side. JANUS can make a traditional snake game more interactive. A player can navigate a snake and guide it through a hole. Then the snake appears on the other side of the screen, and the other player has to finish his/her mission to get the snake back to the previous side. JANUS allows us to do pseudo 3D manipulations as well. If there is a globe on the screen and people can rotate it to find something on it, one user can have Asia on his/her screen while another user is seeing the Americas. JANUS gives an additional graphical layer between two users that can solve problems or inconveniences caused by existing transparent displays. The expansion of virtual dimensions in JANUS provides invaluable experience to users with its unique properties.

This project has been conducted in collaboration with Professor Geehyuk Lee’s HCI Lab. JANUS was exhibited at SIGGRAPH 2014 Emerging Technologies and introduced in The Vancouver Sun as one of the highlights.