What is most needed in order to expand the field of application of OLED Microdisplays is even higher luminance. AR glass applications in particular require visibility under natural light, so there is a strong desire to make displays high luminance. Of course, high luminance technology is also useful in other applications, so there are expectations for it as a key technology that can contribute to achieving longer life-time and lower power consumption for OLEDs.
To address these needs, Sony Semiconductor Solutions Corporation (SSS) has developed an original technology to mold a microlens within a pixel, achieving an improved light emission efficiency of 2.2 times that of the conventional product. Also, by making the beams of light that pass through the microlens more collimated, it achieves the benefits of reducing cross talk between the color filters and improving viewing angle characteristics.
Improving the light emission efficiency with microlens
As shown in the figure below, arranging the microlens on the OCCF (on-chip color filter) within the pixel made it possible to increase the light output efficiency in the forward direction from the luminous layer of the OLED to 2.2 times that of the conventional product. This is also advantageous as a light-emission profile for AR glass and other applications that require high luminance because collimated light beams are generally more desirable in these applications. This technology can also contribute to less power consumption and longer life-time in applications that do not require high luminance conditions.
Improving the viewing angle characteristics by adopting microlens
The light output from the microlens is made more collimated, creating a profile peak in the forward direction. This profile makes it a superior for polarized optical systems and optical waveguide systems for AR glass and similar applications. This profile can also simultaneously contribute to minimizing the interference with adjacent color filters, resulting in an improved angle of view as shown in the figure below. The tristimulus value deviation is low even when viewed from the oblique direction, which has the effect of reducing the coloration.
■ Reference literature
High‐Efficiency OLED Microdisplays with Microlens Arrays
Distinguished Papers, Best of Display Week 2019, Youske Motoyama et al.
Improved the maximum luminance by tenfold in about eight years
In addition to the luminance improvements from SSS’s microlens, by continuously introducing measures to improve light emission efficiency, we were able to gradually icnrease the maximum luminance as shown in the figure below. Going forward, we will continue to work to increase luminance to expand the use cases for our OLED Microdisplays.
Related Products & Solutions
Find out more about the OLED Microdisplay products using this technology.
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