I recently returned from a packed week at SPIE’s Photonics West in San Francisco where I had the pleasure of giving a presentation at the SPIE AR VR MR conference.
It was a great opportunity for me to share the progress FlexEnable has made in integrating a more stretchable transparent electrodes material into our liquid crystal cell making process. These cells are used for making ultra-thin and light dimmers for AR glasses that improve the virtual image contrast in bright light. By selectively attenuating ambient light, electrically tunable dimming cells are essential for making AR glasses all day wearable.
Our conventional liquid crystal cell making process includes indium tin oxide (ITO) layers as the transparent conductors which is a common method. While for applications with flat or single axis (i.e. cylindrical) form factor, using ITO electrode isn’t a problem, we are reaching a limit when deeper biaxial curvature is required.
Biaxially-curved AR devices
Recently we have been receiving more requests to make LC dimming cells in form factors in which they would need to be biaxially curved. Since it is most efficient to manufacture the LC cells in a flat state, obtaining a biaxial curvature requires all the materials to be stretched to a certain degree to obtain the new shape. Most of the materials that make up the LC cell are all plastic and therefore can be easily deformed. However, the ITO layer is ceramic – it is this layer that becomes the first point of failure when deformed.
Luckily most of the exciting applications for 3D curved parts only require a modest amount of stretch, so our cells with the ITO layers are suitable. We have shown that curved LC cells are achievable with an ITO electrode for shapes that require stretching below ~1.5% (e.g. the lenses on typical eyeglasses). However, some advanced visor shapes require stretching greater than 10%. By replacing the ITO layer with a polymer conductive electrode, we have been able to achieve the more aggressive curvatures required.
During the three-day AR VR MR Expo in January FlexEnable showed a range of flat and biaxially curved ambient dimmers for AR glasses. It was great to see so many companies working together to integrate AR glasses components and make them more accessible for OEMs.
If you want to find out more about our biaxially curved dimming cells, contact us at info@flexenable.com for more information.
Ultra-high curvature ambient dimmer
