Design aspects of low power polymer/OLED passive-matrix displays

摘要

Polymer and small molecule organic LED technologies offer many attractive properties for use in a display. The highly efficient light generation at low supply voltages and the limited thickness of the display are advantageous for mobile applications. Furthermore, the large viewing angle, high contrast and fast switching speed give excellent picture quality for text and video mode operation. Optimal uniformity of the passive-matrix display is achieved with current-driven operation. This reduces the influence of material degradation as well as voltage drops across the connection leads. Amplitude and pulse width modulation can be used to obtain grey levels. This presentation discusses design aspects of small-size, full-colour passive-driven polymer LED matrix displays. Consequences of multiplexing, colour sub-pixelation, aperture and display parasitics are analysed and requirements for the RGB materials are formulated to obtain low power dissipation of the module. The efficiency of red polymers, that are available up to now, is too low. This leads to an unbalanced current density in comparison with green and blue which is unfavourable for the display power consumption.