Dynamic voltage scaling of OLED displays

Unlike liquid crystal display (LCD) panels that require high-intensity backlight, organic LED (OLED) display panels naturally consume low power and provide high image quality thanks to their self-illuminating characteristic. In spite of this fact, the OLED display panel is still the dominant power consumer in battery-operated devices. As a result, there have been many attempts to reduce the OLED power consumption. Since power consumption of any pixel of the OLED display depends on the color that it displays, previous power saving methods change the pixel color subject to a tolerance level on the color distortion specified by the users. In practice, the OLED power saving techniques cannot be used on common user applications such as photo viewers and movie players. This paper introduces the first OLED power saving technique that does not result in a significant degradation in the color and luminance values of the displayed image. The proposed technique is based on dynamic (driving) voltage scaling (DVS) of the OLED panel. Although the proposed DVS technique may degrade luminance of the panel, the panel luminance can be restored with appropriate image compensation. Consequently, power is saved on the OLED display panel with only minor changes in the color and luminance of the image. This technique is similar to dynamic backlight scaling of LCDs, but is based on the unique characteristics of the OLED drivers. The proposed method saves wasted power in the driver transistor and the internal resistance with an amplitude modulation driver, and in the internal resistance with a pulse width modulation driver, respectively. Experimental results show that the proposed OLED DVS with image compensation technique saves up to 52.5% of the OLED power while keeping the same human-perceived image quality for the Lena image.