Paperlike Microencapsulated Electrophoretic Materials and Displays
- PDF / 447,531 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 7 Downloads / 207 Views
lutions that offer both the readability and portability of ink on paper.
Paperlike
Microencapsulated Electrophoretic Materials
Microencapsulated Electrophoretic Materials and Displays
Peter T. Kazlas and Michael D. McCreary Abstract Microencapsulated electrophoretic (MEP) materials exhibit high optical reflectance and contrast, wide viewing angle, high resolution, and excellent image stability. MEP materials can be easily printed on large plastic sheets and laminated to a variety of electronic backplanes to construct displays. The combination of a MEP material with flexible transistor technologies enables displays that offer both the look and form of the printed page. This article reviews the basic architecture and properties of MEP materials and describes the integration of MEP materials with transistor backplanes to produce high-resolution, low-power, paperlike displays. Recent developments in ultrathin flexible displays are also reported. Keywords: colloidal materials, electro-optic materials, electrophoretic materials, flat-panel displays, microencapsulated electrophoretic (MEP) materials, optical properties, ultrathin flexible displays.
Microencapsulated electrophoretic (MEP) materials, or “electronic ink,” offer a unique set of performance characteristics for mobile information displays: high reflectance, good contrast ratio (the ratio of maximum to minimum achievable luminance or reflectance), wide viewing angle, and image stability.1–7 A MEP material consists of millions of tiny microcapsules, each one containing charged submicron pigments that move under an externally applied electric field to form an image.1–4 In one embodiment, shown in Figure 1, each microcapsule contains positively charged white titanium dioxide particles and negatively charged black particles suspended in a clear fluid.1,2 When a negative electric field is applied, the white titania particles move to the face of the microcapsule, where they become visible to the user. This makes the surface appear diffusely reflective at that spot. At the same time, oppositely charged black particles move to the back of the microcapsules, where they are hidden. By reversing this process, the black particles move to the face of the microcapsule, which now makes the surface strongly absorbing at that spot. The continuous movement of oppositely charged white and black particles through an optically clear fluid allows for electronically addressable gray states. Particle motion is a function of the electronic impulse across the material given by
qEt dt, T
Today, pervasive computing enabled by the latest advances in wireless bandwidth and processor technologies places new demands on mobile displays requiring higher information content, comfortable reading in dynamic environments, and low power consumption while not compromising device portability. No electronic display technology has ever matched the ease of use of the printed page. Most portable devices such as personal digital assistants (PDAs) employ transreflective-mode twisted-nematic and su
Data Loading...
