What is PDLC film?

The Technology Behind Transparent Projection Surfaces Simply Explained

Anyone encountering digital glass facades for the first time will sooner or later come across an abbreviation: PDLC. It sounds like laboratory jargon, but it describes a technology that works in an astonishingly clear way – and explains why a pane of glass can now perform two completely different tasks.

This article explains what the abbreviation stands for, how the film is constructed, and why it forms the basis of modern projection glass solutions.

What does PDLC stand for?

PDLC is the abbreviation for Polymer Dispersed Liquid Crystal.

The name already describes the structure quite accurately. Millions of microscopic droplets of liquid crystals are dispersed in a thin plastic layer (the polymer). This layer lies between two wafer-thin, conductive films to which an electrical voltage can be applied.

The entire package is only a few tenths of a millimeter thick and can be applied over the entire surface of existing glass panes.

How does the film work?

Liquid crystals have a special property: they can be aligned by electrical voltage.

Without voltage, the crystals in the droplets are randomly oriented in all directions. Incident light is scattered at countless interfaces – the film appears milky-white, similar to frosted glass. It is impossible to see through.

When a voltage is applied, the crystals align uniformly. The light can now pass through the layer almost unhindered – the film becomes clear and transparent. The change happens in fractions of a second and can be repeated as often as desired.

Simply put: Power on = transparent. Power off = milky.

Why is it transparent?

The transparency in the switched state has a physical reason. When the crystals are aligned, their refractive index matches that of the surrounding polymer. For light, the layer then behaves like a uniform material – there are no more interfaces where it could be scattered.

High-quality PDLC films thus achieve a light transmittance that comes very close to the impression of a normal pane of glass. Shop windows remain shop windows, offices retain their daylight, and the architecture appears unchanged.

Why is the milky state so valuable?

At first glance, the opaque state seems like a side effect. In fact, it is the key to the second function of the glass surface.

A milky-white, uniformly scattering surface is physically exactly what makes a good projection surface. While clear glass simply lets projector light pass through, the scattered layer captures the image and makes it visible – brilliant, uniform, and recognizable even from shallow viewing angles.

This results in an elegant daily routine: During the day, the film is switched and transparent, the glass facade fulfills its classic task. After nightfall, it switches to projection mode, and the same surface displays videos, campaigns, or event information.

Where is PDLC used?

The technology originally came from the privacy protection sector: conference rooms, doctor's offices, or hotel bathrooms use switchable glass to create privacy at the push of a button.

In recent years, a second field of application has developed: the combination with high-performance projectors to create digital glass surfaces. Retailers, car dealerships, hotels, and corporate headquarters use this to transform existing facades and shop windows into large-format communication surfaces – without conversion, without LED walls, without interfering with the architecture.

Conclusion

PDLC is not a future technology, but a mature principle: liquid crystals that can be electrically switched between order and disorder – allowing a glass surface to switch between transparency and projection surface.

Exactly this principle forms the basis of Lumerax solutions: The film is applied to the existing glazing, everything remains transparent during the day, and at night the same surface becomes a digital stage.

The next article in this series explains in detail how the interaction of glass, film, projector, and software works.

Further articles

How does projection glass work?
Why does projection on glass work at all?
Projection glass explained: Transparent during the day. Advertising surface at night.