Smart Windows

Facilities for the LCD Industry
Crystec Technology Trading GmbH

Facilities for the Production of Smart Windows - Innovative LC Glass Technology

Production of Smart Windows - Basics

Smart Windows are switchable sun protection windows or privacy windows but also switchable building windows or glazings, manufactured through innovative LC glass technology. They offer flexible adjustment options between transparency and opacity, brightness and dimming. Smart Windows represent a groundbreaking innovation in the world of glazing technologies. Through the smart application of liquid crystal technology, these windows can be switched not only clear or opaque but also milky. This flexibility allows individual control over light transmission and privacy, making Smart Windows an intelligent and practical solution for modern architecture.

The state-of-the-art manufacturing facilities of our Korean partner Shindo utilize cutting-edge technologies, especially the Liquid Crystal Technology , to produce Smart Windows.

LCD Setup

Structure of a typical liquid crystal cell: 1 - Polarizer, 2 - Glass substrates, 3 - Seal, 4 - Spacer, 5 - ITO, 6 - Hard coat, 7 - Polyimide, 8 - TFT

The liquid crystal display (LCD), consisting of only one pixel or a few pixels, allows the entire window or parts of it to be set to the desired state through electrical circuitry. Similar to a conventional LCD, various shades of gray and even color effects can be set.

Compared to windows with electrochromic coating, LC glasses switch faster and offer a larger switching range between completely bright and completely dark or opaque. The production of these intelligent windows is done with proven LCD technology, but without the need for high manufacturing resolution as with smartphone or television displays. However, precise and error-free processing is essential for large glass surfaces.

Manufacturing Techniques

The production of Smart Windows poses a particular challenge for equipment manufacturers, as the glasses are much larger, thicker, and heavier than the substrates typically used in the LCD industry. Additionally, constantly changing glass sizes and shapes are demanded for buildings. Our partner Shindo has specifically addressed this issue and, based on its extensive experience in the LCD industry, can offer all the equipment of a production line. These are individually tailored to customers specifications, substrate sizes, shapes, and throughput times to find the best solution for your process. The following key technologies are crucial:

Ultrasound Cleaning (USC) System

USC Dry Surface Cleaning with Ultrasound

Precise Cleaning Without Wetness

DDry surface cleaning of glass or other substrates using ultrasound (US) prior to the actual manufacturing process ensures thorough cleaning of the glass surface without the use of liquids. This helps prevent any degradation in the performance of LC glasses due to moisture absorption.

Preservation of Structural Integrity

USC removes dirt particles and contaminants gently, without compromising the structural integrity of the glass.

Environmentally Friendly

Since USC is a dry cleaning method, it does not require additional cleaning agents or water compared to wet cleaning methods. This contributes to environmentally friendly production practices.

Efficient Cleaning of Large Surfaces

The process is suitable for mass production of large glass surfaces, minimizing production costs.

Ultrasound Cleaning

TCO Coating System

Transparent Conductive Oxide Coating (TCO Coating)

Transparent Conductivity

n the second step, a transparent, conductive oxide layer is applied. Typically, this is an ITO coating (Indium Tin Oxide). This ITO coating provides transparent conductivity, electrical controllability, and a homogeneous coating with low resistance.

Electrical Controllability

With an indium tin oxide coating, transparent electrodes can be generated. This means that by applying an electrical voltage to the ITO coating, changes in the optical properties of the switchable window can be induced. This electro-optical controllability is crucial for the window's ability to switch between different states, such as transparent and opaque.

Polyimide Coater

Polyimide Coating (PI)

Compatibility of polyimide

Polyimide (PI) is applied as a transparent protective layer on the glass surface. It is compatible with the materials in switchable windows and provides flexibility for various glass shapes.

Alternatives to Polyimide

It should be noted that there are also alternatives to liquid crystal, such as electrochromic materials, electro-optic polymers, PDLC (Polymer Dispersed Liquid Crystal), and electroactive polymers, which can be used in some smart window processes without polyimide coating.

Calendar, Roller Press for Fully Automatic Production Line
Calendar, Roller Press for Fully Automatic Production Line

Rubbing Machine

Molecule Alignment by Rubbing

The rubbing process allows for the alignment of polyimide molecules. This influences the alignment of liquid crystal molecules and enables a uniformly pre-defined transparency or opacity. The contact pressure and the angle of the rubbing roller can be freely chosen.

rubbing machine
rubbing machine drawing

Spacer Spray Coating System

Application of Spacers

Purpose of Spacers

The Spacer Spray System is used to spray microscopically small spacer particles (balls) with a defined size onto the surface of the glass layer. These spacers act as spacers between the upper and lower glass layers, ensuring a uniform gap. Both regular spacers in various sizes and adhesive spacers (sticky) can be used. For high-resolution displays and applications such as smartphones or TV devices, spacer spray technology has been replaced by lithographically produced photo spacers. However, for smart windows, spacer spray technology is more suitable and cost-effective due to the very large glass surfaces.

Curing to Fix the Spacers

Depending on the specific process, after applying the spacers, a curing process is integrated to ensure that the spacers adhere firmly to the surface. This step is crucial for the stability and precision of the distance between the glass layers, which in turn has an impact on the uniformity of the tinting of the switchable windows.

Spacer Spray Machine

ODF Dispenser Machine

ODF Dispenser System for LC filling (Liquid Crystal)

The precise and homogeneous application of sealant and liquid crystal (LC) is crucial for the flawless functionality of the window. The dispenser system plays a decisive role in this.

ODF Technology (One Drop Filling Technology)

This process step is of central importance for the production of smart windows and has a significant impact on the final result. Our systems rely on ODF Technology (One Drop Filling), which allows extremely precise dosing. Before the glass plates are joined under vacuum, the exact amount of liquid crystal is dosed onto the lower glass plate.

High-Precision Dosing

This method requires high-precision dosing, as an excessive amount may overflow during assembly and compression, while too little dosing could leave bubbles.

Homogeneous Distribution

The single-drop method ensures not only accurate dosing but also a homogeneous distribution of the material across the entire glass surface. This is crucial to ensure that switchable windows exhibit uniform performance and optical quality. Thus, the dispenser system significantly contributes to perfecting smart window manufacturing.

ODF Machine
ODF Operational Principle

Vacuum Laminating Machine

Vacuum Lamination

Avoidance of Gas Inclusions

The vacuum laminator presses the upper and lower glass layers under vacuum, where precise pressure distribution and accurate operation are crucial to prevent the formation of gas bubbles.

Vacuum Lamination

Final curing Machine

Curing through UV Radiation or Thermal Curing

Finally, the curing of the entire window takes place. During this process, the sealant and any other materials used in the window are activated and cured through supplied heat or UV light. Simultaneously, uniform pressure is applied to adjust the layer thickness of the liquid crystal. Both thermal and UV curing methods contribute to improving the end product properties of switchable windows. They ensure a stable structure, good adhesion between different layers, and increased resistance to environmental influences. The choice between thermal and UV curing depends on the specific requirements of the materials used and the manufacturing process.

Curing Machine

Our manufacturing facilities stand for efficiency, quality, and state-of-the-art technology. Contact us to learn more about how we produce innovative smart windows.