Basics & Patent Background
The basic idea of this D3-Technology® is the creation of visual content and colors in a pixel structure of a display by:
the physical movement of a colored droplet from a reservoir position into a visible area and the creation of colors by using Cyan/Magenta/Yellow/ colors (CMY, similar to the printing process or known from Inkjet printers,) achieved by stacking multiple liquid layers.
The physical movement of a droplet from one cavity to another cavity in a single layer is achieved by electrowetting principles (EW). EW is a long known physical phenomena which describes the dependency of the contact angle of a liquid droplet to a surface by an electrical field. Applying a voltage to a setting as shown on the left side (water droplet on hydrophobic surface plus bottom electrode) will result in a change of a contact angle of the droplet [from a) to b) and reverse].
In case of adt’s approach the droplet can be moved from one position resp. cavity to another by using structured electrodes with dedicated waveforms. Applying a voltage between a segmented control electrode (here E1 and E2) and the common electrode (here CE) moves the droplet from one position to another. In the absence of an electric field or a voltage below the threshold, the position is held. This corresponds to real bi-stable display operation that can’t be achieved by the single cavity approach of our competitors.
adt’s unique multi-cavity resp. droplet movement approach results in specific set of technology features (as shown below) which offers a clear and beneficial competitive position of the Droplet-Driven-Display-Technology®.
The main features of adt’s Droplet Driven Display Products (RLD-/PLD-Displays) are:
- Complete Bi-Stability (“zero power” resp. “green” display)
- Excellent sunlight readability
(contrast ratio > 1:10; transmission > 85% and a white state reflectance of 75%)
- Transflective operation mode and backlighting possible
- Wide operation temperature range
(-45° C to +120° C w/o temperature control; exceed automotive specs)
- Variable pixel sizes (0.2 to 10 mm)
- Printer-like grey-scale and colour reproduction
- Flexible displays easy achievable
- Passive Matrix driving possible
- Video speed capability (pixel size dependant)
Video speed is given. With increased pixel sizes the speed of movement will be reduced. In case higher speeds with larger pixels are needed modified driving structures have to be developed.
The Droplet Driven Display technology® is offering multiple product parameters that will fit to different application areas and will offer benefits to the application and users:
Variable from 0.2 mm up to 10 mm
(0.3 / 1 / 2 / 3 / 5 / 10 mm)
Number of Pixels
1 / < 10 / < 100 / > 100
Number of Layers
single / dual / multiple layers
monochrome / bi-chrome / 8-colors / full
(on RGB or CMY basis)
low speed / mid speed / video mode
single pixel / business card size / 10 x 10 cm - tiles
glass or plastics (flexible displays possible)
Passive Matrix or Active Matrix
e.g. light shutter
Since its foundation adt AG has been developing a strong patent portfolio. Many of these patents are filed since 2005 and are claiming structural elements of the Droplet-Driven-Display Technology / Products besides application patents.
Although the basic electrowetting driving principle of adt’s displays (and any other competitive electrowetting display technology) can’t be patented as it is known since 1876 adt AG owns a strong patent position related to it’s display technology and products.