We have developed novel active matrix driving technology integrating red-green-blue (RGB) microscale light emitting diodes (micro LEDs) and a microscale integrated circuit (micro IC) in each pixel for the Crystal LED display system. The small size and closely placed RGB subpixels of micro LEDs enabled us to achieve an outstanding contrast ratio even in a bright environment. We also achieved superior luminance linearity and chromaticity stability using accurate pulse width modulation (PWM) driving by micro ICs in the active matrix system. To integrate micro LEDs and micro ICs into a scalable display system, an additional fine-patterned layer was applied to a conventional printed circuit board (PCB). In addition, with precise tiling technology, we could produce a large-scale image providing an immersive visual experience. K E Y W O R D Sactive matrix, Crystal LED display, micro IC, micro LED, pulse width modulation | INTRODUCTIONLight emitting diodes (LEDs) have been widely used in general lighting, traffic lights, backlights for liquid crystal displays, and outdoor billboards. LEDs are currently attracting attention as emission devices for display applications that have high energy efficiency, a long lifetime, high brightness, high color purity, and a short response time. In recent years, the use of microscale LEDs (micro LEDs) for emissive display pixels has been proposed and reported by many researchers. [1][2][3][4][5] We have been developing micro LEDs for high-quality display applications. High-quality display applications require not only the micro-sizing of LEDs but also their uniformity in electrical/optical characteristics, precise assembly technology for arraying them, a driving method, and system integration.In 2012, we demonstrated the first prototype of the Crystal LED display, shown in Figure 1, at the Consumer Electronics Show (CES). 6 The display was 55 inches

We have developed a novel active matrix driving technology integrating RGB micro LEDs and a micro IC in each pixel for the Crystal LED display system. With precise tiling technology, a large‐scale image with superior quality can be produced. We will present related key technologies in this paper.

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