How does PDLC smart glass work?
With no applied voltage, the liquid crystals are randomly oriented and scatter the light which enters. When an electrical signal is applied, the liquid crystals orient themselves parallel to each other, allowing light through.
Why does PDLC glass scatter light?
The liquid crystals change their refractive index in relation to the isotropically transparent polymer in which they are immersed, thereby creating multiple step boundaries throughout the PDLC.
It is this change in refractive index at each boundary which causes light to change course. Since the PDLC material contains millions of liquid crystals, each with a boundary facing a slightly different way, the light is scattered in many directions.
The net effect is to hide whatever is behind the PDLC smart glass.
Are the only states of PDLC just ON and OFF?
No, the transmittance (level of transparency) of the PDLC can be varied from 0% in the OFF state up to any value you want until you reach the maximum transmittance (normally 70% or 80%). This is done by simply altering the voltage from 0 VAC up to 70VAC, which is typically the maximum recommended voltage. This can be done electrically with a variable isolating transformer, or electronically with a switched-mode smart glass dimmer.
Can smart glass/film be used as display screens?
Yes, smart glass/film is a rear projector screen with wide viewing angles. Even from the side one can enjoy clear, beautiful images and also in bright locations with high functional projectors.
Why does PDLC require a polymer?
The polymer allows the liquid crystals to be embedded into a film, which can then be sandwiched between panels of glass or plastic. The polymer has constant optical properties which do not vary across its structure, and hence is considered isotropic.
In contrast, the liquid crystal itself is anisotropic, since its optical characteristics are not constant across its structure, but rather can vary under application of an electric field.