Electrophoretic displays

Brain CBP-I has a molecular weight of 13,000 and contains no constituents other than amino acids. It does not display electrophoretic heterogeneity in the presence of calcium and may easily be distinguished... 

An example of the results obtained in the form of a chromatoelectropherogram can be seen in Figure 9.6. The contour type data display showed the three variables that were studied, namely chromatographic elution time, electrophoretic migration time, and relative absorbance intensity. Peptides were cleanly resolved by using this two-dimensional method. Neither method alone could have separated the analytes under the same conditions. The most notable feature of this early system was that (presumably) all of the sample components from the first dimension were analyzed by the second dimension, which made this a truly comprehensive multidimensional technique. 

Sunohara, S. Kitamura, T. 2007. Investigation of color electrophoretic display utilizing electrophoretic colored particles. Nippon Gazo Gakkaishi 46 247-253. 

Materials in a colloidal state are frequently preferred in industrial processing operations because their large surface areas per unit volume enhance chemical reactivity, adsorptive capacity, heat transfer rates, and so on. Therefore, one cannot overlook the importance of the flow behavior and properties of colloids since they exert a significant influence on the performance, efficiency, and economy of the process. Note that some examples of this (e.g., ceramic processing, electrophoretic display devices, and food colloids) were mentioned in the vignettes presented in Chapter 1. In addition, one often uses the flow properties and behavior of the products as measures of the microstructure (or, morphology ) of the products and as a means of quality control (e.g., printing inks, toners, paints, skin creams, blood substitutes,... 

Even in the absence of a colloid, an electrolyte solution will display electroosmotic flow through a chamber of small dimensions. Therefore the observed particle velocity is the sum of two superimposed effects, namely, the true electrophoretic velocity relative to the stationary liquid and the velocity of the liquid relative to the stationary chamber. Figure 12.10a shows the results of this superpositioning for particles tracked at different depths in the cell. The particles used in this study are cells of the bacterium Klebsiella aerogenes in phosphate buffer. Rather than calculated velocities or mobilities, Figure 12.10a shows the reciprocal of the time... 

Biaxially oriented films such as PET and PEN are birefringent. For LC displays which depend on light of known polarization this means that birefringent films, which would change the polarization state, are unlikely to be used as substrates. Films based on amorphous polymer are not birefringent and are more suitable for LC displays. Birefringence is not an issue with OLED, electrophoretic displays, or, indeed, some LC displays. 

Dodabaiapur, B. Crone, V. R. Raju, V. Kuck, H. Katz, K. Amundson and P. Drzaic, Paper-like electronic displays Large-area rubber-stamped plastic sheets of electronics and microencapsulated electrophoretic inks , PNAS, 98, 4835 (2001). 

For example, active-matrix backplanes for reflective displays using electrophoretic media is a potential application for large-area electronics. Electrophoretic media are usually charged colored particles suspended in an insulating fluid [35-37]. When the fluid is held in an electric field between two conductive plates, the particles will move between the plates creating a dark or a reflective state. Because the contrast in an electrophoretic display is because of reflection, no backlight is required and the display has relatively low-power consumption compared with a transmissive liquid-crystal display. 

Fig. 11.19. Photograph of a electrophoretic media display integrated on to a digital lithographically processed a-Si H backplane. The substrate in this example was glass.

Bi-level driver chips drove the active matrix displays with data potential levels around 0 V (low) and 20 V (high). The counterplate potential was held constant. Figure 11.19a shows a photograph of an electrophoretic display driven by an amorphous silicon backplane that was patterned on a glass substrate using wax printing. In this display the electrophoretic ink was a black and white two-particle ink. Figure 11.19b shows the same display addressed with a different pattern. 

The electronic ink is supplied by E ink corporation (Comiskey 1998). The film consists of electrophoretic microcapsules in a polymer binder, coated on to a 25 pm polyester/indium tin oxide sheet (Fig. 14.10). Optical contrast is achieved by moving black and white sub-micron particles with opposite charge in a transparent fluid within a microcapsule. Depending on which sub-micron particles are closest to the viewer, light is scattered back (white state) or absorbed (black state). The electrophoretic effect is multi-stable - without any electric field the microcapsules keep their switching state. This greatly reduces the power consumption of the display (Ritter 2001). 

Because the electrophoretic display effect that is used is multi-stable, the row drivers are only operational during an image update. This is different from the commonly used LC display effects that need to be driven continuously during use of the display. In view of bias stress effects, this makes the electrophoretic display effect ideal for integration of row drivers in organic electronics. 

---