E-Paper Displays

12Optical Measurements for E‐Paper Displays

Karlheinz Blankenbach

Pforzheim University, Display Lab, Tiefenbronner Str. 65, 75175 Pforzheim, Germany

12.1 Introduction

There are two types of direct view display technologies (beside projection): Displays that modulate their reflection of ambient light and emissive or permanently backlit displays which convert electrical power to light. The fundamental characteristics of emissive displays like luminance and color are measured under darkroom conditions. That is relatively easy to perform compared to measurements on reflective displays, which must be illuminated. The main challenge here is that the results depend on the actual set‐up and geometry of the illumination, the display (e.g. angular reflection characteristics), and the measurement device. This applies as well for emissive displays when measuring their ambient light performance. A very widely used and comprehensive display measurement standard is the SID IDMS [1] (especially Chapter 11 “Reflection Measurements”). For example, additional background information on display measurements with explanations can be found in, e.g. [2]. These two references contain all the information necessary to understand and perform detailed reflective display measurements.

The structure of this chapter is as follows:

• The fundamentals of the physics of reflection are the basis for understanding the procedures for reflective measurements.
• Examples of measurement set‐ups such as those using a ...