Benefits of flexible LC cells and their applications
November 15, 2022
Liquid crystals are used in many types of display devices including TVs, monitors, smartphones and VR/AR headsets. In simple terms, they selectively transmit light and produce images on the screen. In a previous blog entitled ‘The making of a plastic liquid crystal cell’, our Technical Director Mike Banach explained how liquid crystal (LC) cells are traditionally made on glass and how FlexEnable’s low temperature processing enables the manufacture of flexible LC cells on bioplastic TAC substrates.
In this blog, we’re focusing on the key applications for flexible LC cells and the benefits they bring.
Benefits of flexible LC cells
Ultra-thin and ultra-light
Measuring just 100μm means that LC cells add almost no thickness and weight to a device. Because of this they can be stacked to increase dynamic range, creating more powerful lenses for AR and VR headsets, for example.
Large area optical films
As they are made on bioplastic films, LC cells can be used to make large area optical films thatactively steer, modulate and focus light, expanding their applications. For example in the automotive industry, they can be used to make smart windows that control the amount of light that enters the car.
3D biaxially formable
One of the biggest advantages of flexible LC cells is that they can be biaxially thermoformed to follow the complex curvature of many real-world surfaces such as fixed lenses, visors or car windows. Low temperature processing allows substrates with a low glass transition temperature (Tg) to be used, so that the resultant LC cell can be thermoformed at (low) temperatures benign to the rest of the cell. Thermoforming is undertaken using a combination of heat and pressure against a forming plate. Our team has proven that both the LC cell and the film components necessary to operate the shutter can be thermoformed to a spherical bend radius <100mm.
Flexible LC cells are designed to be manufactured in existing factories originally built to make glass displays, prolonging the life of existing production facilities and equipment. Widely available bioplastic films made of a cellulose are used (Triacetyl cellulose - TAC) made possible because the entire cell manufacturing process is undertaken without exceeding 100°C, which also significantly reduces the energy footprint during manufacture compared to glass-based large area electronics
A world of applications
Because of their ability to be stacked together to create powerful and combined functions, flexible LC cells are particularly needed in the following applications:
LC optics for AR/VR
In AR/VR applications flexible LC cells allow two key functions: 1) tunable LC lenses and 2) ambient dimming. Tunable LC lenses allow the focal depth of the image to be adjusted to match the perceived depth, thereby increasing realism and user comfort. In AR headsets, the ability to selectively adjust the perceived brightness of the real world is needed. Ambient dimming helps to ensure that the virtual image remains high contrast and realistically blended in real-world conditions with high brightness. FlexEnable’s LC optical films can be segmented or pixelated with active matrix, to give even greater control, and allowing black regions to be included in the projected image.
Tintable smart films
There is an increasing demand for car windows and sunroofs that can change tint at a touch of a button. This is not only to control how much daylight and heat gets into the car, but also to change the user’s environment. FlexEnable’s LC cell technology can conform to the biaxial curvature of car windows while achieving rapid tint switching with colour neutrality.
Ultra-thin switchable privacy screens
Liquid crystal-based ePrivacy technology can be integrated into the display of notebooks with virtually no thickness and weight added – unlike existing solutions on glass. It allows the viewing angle to be actively adjusted between wide and narrow using an integrated solution that can be switched on and off at the touch of a button.
For more information on liquid crystal optics, please contact us at firstname.lastname@example.org.