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A reflective display based on electrowetting Disclosure Number: IPCOM000029873D
Publication Date: 2004-Jul-15
Document File: 3 page(s) / 134K

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A reflective display based on electrowetting

Reflective displays are generally considered to be one of the main display technologies for the future. The mobility of consumers is rapidly increasing, and many applications involve a display for information exchange. Reducing the power consumption in portable applications is a high priority.

 Electrowetting is an attractive technology for use in high brightness reflective displays. With the electrowetting display principle (Fig. 1), a colored oil film is moved aside by electrowetting, thereby rendering the optical stack transparent at those places where the oil has been removed.  When a diffuse reflector is positioned below the oil in or under the optical stack, a reflective display pixel is realized.

Figure 1 Principle of an electrowetting display: the left hand side picture shows the OFF or black state and the right hand side picture shows the ON or white state.

A high brightness color display (67% color conversion factor) can be made with this principle, for instance when a CMY color filter is combined with two switching oil layers in each sub-pixel is summarized in Fig. 2.

Figure 2: The colour electrowetting display principle with two switching colour layers

This principle has some disadvantages:

  1. It uses colour filters.
  2. Different colour CMY oils must be dosed to each substrate
  3. Each oil layer requires a separate driving substrate.

Another option is the use of three switchable monochrome (C, M or Y) layers, which has the adv...