Displays impress with their luminosity, high resolution and brilliant colors. They have one thing in common: when they are turned off, a black hole remains. You can't see through them. Transparent displays, on the other hand, are available in various technologies. Similar to a pair of glasses for augmented reality, it can allow you to see through to the workpiece on a machine or to the exhibits in a shop window, providing additional information about them.
The basic requirement for transparency is that the display technology allows light to pass through the panel. This is not the case with reflective TN such as in calculators or ePaper. The display can then hide individual segments (e.g. TFT) or add content (transparent OLED or transparent LED module).
Special attention must be paid to the design of the content. The color "black" does not exist - there the display is simply transparent and shows the background. To show off the transparency, the displayed content must consist of slim lines rather than large areas.
In contrast to Asia, transparent displays have not yet gained widespread acceptance in Europe. Ideas for applications already exist:
Different technologies are suitable depending on the application and viewing distance.
Outdoor digital signage displays need to be large so they can be read from a distance. Displays such as wayfinding signs through the mall, on the other hand, need a low pixel pitch because they are viewed up close. The figure shows a relationship between the distance of the viewer and the necessary spacing of the pixels of a display. The y-axis shows the corresponding distance at the pitch given in the x-axis. Two conclusions can be drawn from this: To achieve the same impression as on the TV set, the pitch should not be larger, i.e. not below the straight line. To achieve the same impression, however, the pitch does not need to be finer either, i.e. it does not need to be above the straight line.