Makoto Omodani

10.1: Invited Paper: What is Electronic Paper? The Expectations

The expectations for Electronic Paper can be summarized as flexibility, readability, and multi-functionality. This paper focuses on the goal of readability. Paper-like readability should be accepted as the most important target of Electronic Paper, when we consider that no existing electronic display is as comfortable to read as paper. A concept of readable Electronic Paper is proposed, and its expected properties, style variations, applications, and various candidate technologies are summarized. As an indication of the realization of readability, an evaluation of user comfort when conducting reading tasks on paper and an LCD shows that free handling of the medium is an important factor in achieving excellent readability.

P‐47: Novel Evaluation Method for Visibility of Reflective Electronic Paper Display by Comparative Examination with Liquid Crystal Display

An organoleptic examination technique is proposed for evaluating visibility of reflective electronic paper display (EP). The visibility of EP was compared with that of LCD under various ambient illuminances. The threshold illuminance, above which the visibility of EP was better than that of LCD, was successfully extracted.

66.2: An Approach for Achieving Ideal Readability on Electronic Paper: Extraction of Essential Disadvantages in Conventional Displays

This study aims to clarify the factors behind readability of paper documents; the clarification is intended to yield good guidelines for realizing truly readable Electronic Paper. Proofing tasks were prepared on various reading conditions; display area was varied from 1/2 page to 4 pages on the screens. Performance is shown to increase with the number of pages simultaneously provided. This result agrees to our general impression that we generally feel that it is difficult to complete proofing tasks on a computer screen, which usually provides less than one page.

A study on the reason why prints made with only cyan and magenta inks look like regular full-color prints

Two-tone color prints are often commercially used for low-cost color image reproduction. We sometimes can recognize the color which should not be expressed by the ink set of only two colors. Remarkable example is seen in prints made with ink set of cyan(C) and magenta(M); they look like rather regular full-color prints and missing yellow(Y) color is often recognized in the prints. Color appearances were compared in subjective evaluations between three types of two-tone prints: C+M, M+Y and Y+M. Superiority of C+M prints were reconfirmed and the reason was set as a target of our study to be clarified. We suppose that our natural color constancy works when we recognize two-tone color prints. This supposition is derived from an analogy of the case when we see objects under a colored light or through a colored filter. We attempted to explain the reason by considering the von Kreis model, which describes the chromatic adaptation to changes of lighting conditions. The von Kreis model is considered as a basis of many kinds of advanced color appearance models; the essential principle is liner gain-controls for the three components of colors. Color components were measured on selected typical points on printed images of C+M, M+Y, Y+C prints and C+M+Y print as a reference. The von Kreis coefficients were calculated by using measured results on the same typical points which show nearly black in C+M+Y prints and in each two-tone color prints. Colors of the typical points on the C+M+Y prints were estimated from two-tone color prints by a calculation using the von Kreis coefficients. Consequently, best estimation was derived from the calculated results on C+M prints. This result indicates the advantage of C+M prints for us to activate our color constancy easily. It was indicated that the same kind of compensation mechanism as is supposed under a colored light is possible for the color recognition on C+M prints: von Kries model could successfully estimate colors of C+M+Y prints from C+M prints. Thus, we conclude from this result that C+M prints tend to look like full color prints because we can easily compensate colors of C+M prints by using linier gain-control scheme at our natural vision system.

Surface electric charge driving of liquid crystal medium by using an ion projection head

This study aims at driving a liquid crystal medium without using address electrodes or driving circuits; surface electric charging is used instead. This driving method can yield displays that are more compact and lower in cost. This style of LCD well fits the concept of digital paper. We examined the basic display characteristics of a guest-host PDLC when the surface electric charge is formed using the ion projection method. Repeated image formation and erasure on PDLC device by ion projection and heating were confirmed. Plain display characteristics that were independent of viewing angle were obtained. These results indicate that guest-host type PDLC devices are interesting candidates for realizing the concept of digital paper.