Yazaki says it has brought an automotive industry first to market by using an optical coupling adhesive in a vehicle instrument cluster to create a more seamless appearance and improve display content visibility and clarity for the driver. The company partnered with a leading domestic original equipment manufacturer to develop the new design, resulting in a high-end appearance to match the luxury vehicle’s interior.

“Our engineering teams worked closely with our customer to deliver an innovative instrument cluster that goes far beyond luminance and image clarity requirements, resulting in a breakthrough display product,” said David Scheffler, Yazaki North America Head of Engineering. “The cluster delivers best-in-class appearance in power-off mode and a true seamless appearance in power-on mode.”

The company was able to keep the new tech cost-competitive by using existing processes and mature components in a new way to create a more luxuriously look, added Michael Boyd, Senior Manager, Advanced Development, Yazaki North America.

Yazaki developed and refined the process to bond the TFT (thin-film-transistor) LCD (liquid-crystal display) to a flexible tinted polycarbonate film to consistently and efficiently manufacture the display. By laminating the display to the tinted applique, the optical adhesive raises the TFT image to the applique front surface, resulting in overall cosmetic improvement in appearance that shows no visible cut lines, gaps, or transitions between the analog gauges. The use of optical coupling, most commonly seen in smartphones, also minimizes reflection and eliminates air gaps and their associated issues, such as debris and moisture.

To make sure luminance (measured in candelas per meter squared) and image clarity met expectations, the brightness needed to be high, as the light needs to pass through a tinted cluster surface, said Boyd. “It is not that the cluster is brighter than others. It needed to be as bright at others, even though the light is passing through tinted glass.”

Regarding the bonding agent between the TFT and polycarbonate, Boyd clarified that “it is an optically clear adhesive (light passes through the TFT, the adhesive, and the glass without creative reflections). Reflections reduce brightness and clarity; it would look dull and blurry. By using polycarbonate, it gives the display a matte finish in the power-off position, while allowing light to pass through without scattering when it is on, and retaining clarity.”

The project was a collaborative effort among the customer, Yazaki, and its supply base.

“Our OEM customer wanted a certain look to the cluster, inspired by the cell phone industry,” said Boyd. “They wanted to create a bit of mystery to the look of how the information was going to be displayed. We worked with our design studio and advanced engineering team to come up with solutions. We then talked with manufacturing process experts to come up with a way to produce it.”

Among the biggest development hurdles that had to be overcome was the “challenge of matching the two types of TFT displays that are packaged in the cluster in a harmonious way that is pleasing to the eye,” explained Boyd. “The other challenge was taking a consumer electronics manufacturing process and industrializing it for the automotive environment.”