Amorphous oxide TFT and their applications in electrophoretic displays

Abstract

Applications of amorphous oxide TFTs to electrophoretic display have been demonstrated. First, we focus attention on the low process temperature of amorphous In–Ga–Zn–O (a‐IGZO) TFT and successfully fabricated a‐IGZO TFT array onto poly‐ethylene‐naphthalate (PEN) films at room temperature. Subsequently, an a‐IGZO TFT array was combined with electrophoretic display and we have successfully driven a flexible electrophoretic display by a‐IGZO TFT. The image of the flexible display was not affected by bending. Secondly, taking advantage of the transparency of oxide TFT, we propose a novel display structure for electronic paper. In our display structure, an oxide TFT array is fabricated directly onto a color filter array, which facilitates good alignment of the color filter and the TFT array. This TFT and color filter array were laminated with electrophoretic frontplane and positioned at the viewing side of the display. In this structure, the electrophoretic display is driven from the viewing side of the display, which we call the “Front Drive” structure. We have successfully displayed QVGA 4 inch color electronic paper by the “Front Drive” structure.