New "black" light-control film blocks 95% of visible light when power is off
Tokyo-based Toppan has developed a new “Normal Black” grade of its LC MAGIC™, a liquid crystal light-control film that changes from transparent to opaque with the flick of a switch (above).
"Normal Black" is black with a visible light transmission (VLT) of only 5% when power is off. Automobile windows and sunroofs using the film can create a bright and open space when power is on, yet ensure privacy when power is off. This can eliminate the need for shades with motors or moving parts, improve comfort, and make vehicles lighter.
The shift to electric vehicles (EVs) and progress toward full-driving automation are expected to transform automobiles into places to relax. The role of automobile windows will also change. At level 4 “high driving automation” or level 5 “full driving automation”, vehicle interiors will become more like living spaces, and windows will need to protect privacy. Shades, curtains or other mechanical features, however, entail moving parts in multiple locations, not only taking up interior space, but also adding weight and consuming more power, which will impact the range that EVs can offer from a single charge.
In next-generation automotive design, manufacturers will likely seek to extend range, reduce weight, and enhance interior comfort. This will be aided by technologies that integrate sunroofs and windows into interior design without using motors or moving parts. Several light control glass and film products such as Toppan’s LC MAGIC™ are already available, but the level of technical difficulty involved means that it has so far been challenging to commercialize a “black” model for interiors with high-end design.
Toppan has now enabled a black color that shields 95% of visible light when power is off and a translucent light gray color allowing 43% of visible light to pass through when power is on. Toppan aims to launch mass production of LC MAGIC™ Normal Black in 2024, making samples available to the mobility industry, including the automotive, aviation, and rail sectors.
Toppan currently offers a “Normal White” grade, which is transparent when power is on and cloudy white when power is off, and a “Reverse White” grade, which is cloudy white when power is on and transparent when power is off. With the addition of LC MAGIC™ Normal Black, manufacturers and consumers will be able to select the grade that best matches the interior of each vehicle.
“The ‘Normal Black’ grade of LC MAGIC™ provides a number of advantages as we move towards a future that sees more widespread use of electric and self-driving vehicles,” says Fumio Ohnuma, gm-light-control device development at Toppan. “It can help provide a greater level of comfort and privacy for people inside vehicles while delivering benefits for manufacturers and designers due to its light weight, low power consumption, ease of application, and seamless blending with interiors.”
Features of LC MAGIC™ Normal Black
- Random positioning of dye within the layer structure achieves a VLT of 5% when power is off, meaning vehicle interiors cannot be seen from outside and external light can be blocked even on a clear day.
- Because dye aligns in a preset direction, up to 43% of visible light is allowed to pass through when power is on, a VLT level equivalent to that of rear windshields of general automobiles. Brightness is sufficient for people inside a vehicle to be discernable from the outside.
- Material selection and an original layer structure with UV protection prevent discoloration even when the film is used outside for long periods and ensure that VLT when power is off is unaffected .
- LC MAGIC™ can be easily applied after glass production is complete because the thickness of the film is approximately 0.4 mm. It can also be cut into any shape due to a structure in which liquid crystals do not move inside the film.