Apple's Display Team is also exploring the use of ferroelectric liquid crystal on silicon (fLCoS) display panels for AR/VR Glasses+
Earlier this morning, Patently Apple posted a report titled "Apple continues to Explore the use of LCoS Displays in Future Devices such as AR Smartglasses, Macs and more." In another patent that we discovered in Europe this morning, we see that Apple is also working in parallel on a similar display technology that they refer to as ferroelectric liquid crystal on silicon (fLCoS) display panel. Apple's display team have worked on this since 2020. The patent was published in Europe on August 16, 2023.
Apple notes in their patent that an electronic device such as a head-mounted device may have one or more near-eye displays that produce images for a user.
The head-mounted device may be a pair of virtual reality glasses or may be an augmented reality headset that allows a viewer to view both computer-generated images and real-world objects in the viewer's surrounding environment.
The display may include a display module and a waveguide. The display module may include a spatial light modulator such as a ferroelectric liquid crystal on silicon (fLCOS) display panel and illumination optics.
The illumination optics may include light sources such as light emitting diodes (LEDs) that produce illumination light. The illumination light may be provided with a linear polarization and may be transmitted to the fLCoS display panel. The fLCoS display panel may modulate image data (e.g., image frames) onto the illumination light to produce image light. The waveguide may direct the image light towards an eye box.
The fLCoS display panel may include at least a ferroelectric liquid crystal (fLC) layer and a backplane. The backplane may receive the illumination light through the fLC layer. The background may reflect the illumination light as the image light. In order to maximize the reflectance of the fLCoS display panel and thus the optical performance of the display module, the backplane may be a silver backplane or a dielectric mirror backplane.
In some cases, silver allow may be used to improve stability. In addition, the fLCoS display panel may have a cell gap that is equal to a wavelength divided by four times the birefringence of the fLC layer. In order to further optimize the optical performance of the display module, the wavelength used in determining the cell gap may be a green wavelength between 500 nm and 565 nm.
Apple's patent FIG. 2 below is a top view of an illustrative optical system for a display having a display module that provides image light to a waveguide. The Display Module includes an fLCoS panel.
(Click on patent Figure to Enlarge)
For more details, review Apple's in-depth European patent application number EP4226210.
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