Photolithography Fabricated Spacer Arrays Offering Mechanical Strengthening and Oil Motion Control in Electrowetting Displays

Abstract

Introducing spacers into pixelated electrowetting displays (EWDs) normally gives mechanical strengthening, while bringing undesired disturbance of water/oil interfacial dynamics. Hence, spacer array is a key pixel structure needs careful consideration in the design and fabrication of electrowetting displays. Here, we propose a spacer array, which is designed standing on the junction of adjacent pixel walls, fabricated by photolithography. The spacer array provides mechanical strength enhancement and reliable oil motion controllability. By optimizing the spacer distribution density, the EWD device may achieve 28% increase in open ratio (white area fraction) and withstand 60 N/mm2 pressure. This design of spacer array reasonably solves the contradiction between mechanical strength enhancement and optoelectronic performance in EWDs, providing potential applications in oil–water two-phase microfluidic devices.

67‐3: Invited Paper: Progress in Electronic Paper Displays: Color Video Electrofluidic Display Technology

“…We introduced spacer arrays (SAs) on the junction of pixel walls fabricated by a second photolithography process (Figure 8). [16] The introduction of SAs gave improved oil motion uniformity and white area fraction, as well as enhanced mechanical strength of the electrowetting display device. Meanwhile, the switching with spacer array was reversible.…”

“…Red arrows at the side view show the oil motion directions during opening or closing of EWD devices. [16]…”

Driving Waveform Design of Electrowetting Displays Based on an Exponential Function for a Stable Grayscale and a Short Driving Time

“…Then, the aperture ratio could reach the maximum value when the voltage was increased to 30 V. In the falling-voltage stage, the aperture ratio could be closed to 0 when the voltage was reduced to 5 V. Hence, the aperture ratio of the pixels was different between the rising-voltage stage and the falling-voltage stage at the same voltage value, as shown in Figure 3. In addition, it is easy to break through the hydrophobic insulation layer if the voltage is too high, which can cause damage to the EWD pixels [28]. Therefore, the maximum voltage of the driving waveform was set as 30 V.…”

Design of Driving Waveform Based on a Damping Oscillation for Optimizing Red Saturation in Three-Color Electrophoretic Displays

“…As the carrier of human–computer information interaction, a flat panel display is very important in modern life. In recent years, electronic paper displays, which are a new type of display, have occupied a certain share in the display market due to its advantages such as large viewing angle, light in mass, low power consumption, repetitive erasing, and readability under sunlight [ 1 , 2 , 3 , 4 , 5 ]. As a kind of electronic paper display, electrophoretic displays (EPDs) have an excellent performance in the field of device manufacturing, which is expected to become one of the mainstream technologies for next-generation displays [ 6 , 7 , 8 ].…”