Nouvoyance

Pentile OLED is designed to allow for high resolution with high brightness, equivalent lifetime and improved manufacturability.

AM OLEDs (active matrix organic light emitting diodes) are an emerging technology with many properties that have been created customer enthusiasm:

• Superior color gamut
• Extraordinary viewing angle performance
• Video fast response time
• Power savings for many types of image content
• Ultra-thin design
• More rugged than LCDs

It has been a challenge to fabricate OLEDs in the high resolution formats that are needed for smartphones and other mobile product designs. With such high pixel density it is difficult to use the shadow mask process for depositing the OLED material. Also, to attain the high brightness that is expected for smartphones, the current density that is experienced for RGB stripe designs becomes excessive, forcing manufacturers to make compromises in brightness and/or lifetime.

All PenTile OLED displays process data at a full 24-bits of color, however some handset makers offer only 5-6-5 color as an input to the PenTile OLED driver chip. Be assured that internally the data is processed at even higher bit depth to enable a superior viewing experience. Using methods similar to the subpixel rendering (SPR) that is used for PenTile RGBW for LCDs, a new layout, together with a corresponding set of image processing algorithms, optimizes the performance of PenTile OLED for mobile applications.

Shown below is the layout for RGB stripe, compared to the layout for PenTile OLED. Note that the green subpixels are half as wide as the red or blue and there are more of them. This has been done to take advantage of the sensitivity of the human vision system to the localization of green subpixels. While the human eye cannot localize blue subpixels very well, we are very capable of localizing green. Reducing the number of subpixels also allows for a better fill factor and a reduced current density, leading to extended lifetime at higher brightness.

PenTile OLED now only requires 4 columns to write one black and white line pair, rather than the 6 required for a legacy RGB stripe design. Together with this layout, there are special algorithms that analyze the images for special features and apply adaptive image processing to reduce artifacts associated with moiré, aliasing and other detriments to the visual experience