JDI Discloses Details of Its See-through Display
Color filter, polarizing plate eliminated
Japan Display Inc (JDI) disclosed the details of its see-through display that was announced in January 2017.
The details were announced at the Society for Information Display 2017 (SID 2017), an academic conference that took place from May 21 to 26, 2017, in Los Angeles, the US (thesis number: 79.4).
The see-through display is a transparent panel when the display unit is off. And an image is shown on the panel when the display unit is on. It features a light transmittance of 80%, which is more than 50% higher than that of JDI's previous see-through display. As a result, the background can be clearly seen through the panel (See related article).
This time, JDI developed a totally new panel structure. First, to realize a see-through LCD display as thin as a plate, the company employed a structure in which LED light comes in from the lateral sides of the liquid crystal cells in place of the previous backlight structure. The LED light goes while being totally reflected in the liquid crystal cells. At this point, when the LCD panel is seen from above, it looks transparent.
When an electric field is applied to the liquid crystal cells, the orientation of liquid crystal molecules changes so that LED light coming to the cells is scattered, displaying an image on the LCD panel. At this point, when the LCD panel is seen from above, the LED light seems being scattered. By using the switching between "transparent" and "scattering" for display, the need for a polarizing plate was eliminated.
Furthermore, to make a color filter unnecessary, red, green and blue LEDs are alternately lit, and pixels are turned on/off accordingly (CFS (color field sequential) method). To realize color display with the CFS method, JDI newly-developed a fast-response liquid crystal material that can switch between the transparent and scattering states at a high speed.
The specifications of the new see-through display are as follows.
Screen size: 4 inches
Pixel count: 300 x 360
Drive frequency: 180Hz (1 field)
Light transmittance: 80%
Contrast ratio: 16:1
Color gamut: 112% on NTSC standards