Practical measures of three-dimensional stretchability on stretchable displays

Unlike existing flexible display technologies such as foldable, rollable, or slidable displays, stretchable displays can change the size of surface areas. Furthermore, they can be transformed into a multi-curvature shape in any direction. These may be the reasons they are often called freeform displays. Stretchability, the extent displays can be stretched, is one of the most important performance factors of stretchable displays. The length ratio before and after stretching is widely utilized to represent one- or two-dimensional stretchability. However, the length ratio cannot be directly applied to three-dimensional stretching. Hence, this paper introduces new measures of three-dimensional stretchability. The pros and cons of the proposed measures are explained. In addition, experimental results to evaluate the proposed measures’ performance are presented.