There were a lot of attempts to create a transparent display. The most recent one was made by Japan Display Inc. The company unveiled their version of this display with the transparency coefficient of 80%. This is twice as much compared to previous devices of this kind.
Japanese engineers managed to achieve this high level due to a new production technology. The display itself had an absolutely new structure without a colour filter and a light-polarizing plate. Unfortunately, the company keeps this technology in secret. All we know is that the display is based on liquid crystals. Manufacturers say that more detailed characteristics will be revealed during SID (The Society for Information Display) conference in March. This is where the latest version of this display will be shown to the public.
Until that time we have to be content with some basic specs. The current prototype has a 4-inch diagonal, 300×300 resolution and 117ppi pixel density. Manufacturers are very optimistic about their invention. Devices with these displays can be used as screens in e-book readers, watches, smartphones, augmented reality devices, billboards, smart windows, and so on.