Seconds after hearing the impact, you may be reluctant to look for damage. Just how much damage was done to the inside of your phone? No matter the outcome, it’s a feeling we can all relate to – but 3M scientists Gerrad Bailey and Bryan Hunt react differently. For them, destruction is part of the creation process.
To test the durability of the film technology inside smartphones, they drop ceramic and steel balls onto films found inside. “The first instinct is to cringe when the ball drops on the actual film,” says Gerrad.
Gerrad and his team in 3M’s Display Materials and Systems Division replaced this fear with excitement by developing a tougher version of a film that sits inside your phone’s display, and is specifically designed to improve the brightness of the display.
“With this film, we don’t have to cringe anymore,” says Gerrad. “At the end of the ball-drop test, the film material will recover enough that you won’t be able to see any damage.”
It’s a film that joins a number of components within your smartphone display. They’re components that you want to protect, especially since the energy from any source of impact can transfer from the outside of your phone’s display to films located deep in your device, explains Bryan, who works with Gerrad as a lead research specialist at 3M.
“I think a lot of people don’t realize that the display itself is not just the glass that they’re touching,” adds Gerrad. “There are a lot of layers underneath the glass that all affect the performance of the display and the image that you see.”
Within these layers, you will find many technologies – such as adhesives and electronic grade coatings – working to protect the inside of your phone. “We try to simulate the full system when we perform the ball-drop test,” says Gerrad. “That way, when the ball hits the film, there are additional layers that the impact will have to transfer through – just as you would experience in real life.”
Why test durability? Because your smartphone is your portal into the digital world. You want the display image to perform the best it possibly can.
“Displays have been on a trend of being thinner, lighter and brighter,” explains Gerrad. “Smartphones, mobile devices and portable devices are ubiquitous. They are everywhere around the world. Without these devices, it is difficult to be digitally connected.”
We want to be able to take our devices everywhere we go – and we expect them to hold up. This means that the display and the rest of your device has to remain robust as you go about your daily activities, often not thinking about protecting your phone from damage.
“You might put your phone in your pocket and sit on it with your keys pressed up against it. Or, you might be out mountain biking and drop your phone on rocks,” adds Bryan. “We created films that resist being damaged, which helps prevent spots within the phone’s display during exposure to impact.”
Durability joins a list of other expectations we have for our devices. We also want them to last longer by using less energy, while remaining thin and bright.
To meet these needs, scientists at 3M developed a durable brightness enhancement film for LCD displays. It’s designed to make our devices thinner and brighter, while allowing them to maintain their robust performance.
“The materials that were chosen for this brightness enhancement film are softer and more recoverable than previous generations of this film,” says Gerrad. “As they encounter damage, they recover from that damage.”
This is because the materials inside the films contain a prism structure made by a microreplication process, where 3M’s special shape-memory technology is used to keep the structure of the film light, but also strong. The result? The film’s materials help to absorb more energy without permanently deforming or breaking. “They compress and then come back to their original shape,” explains Bryan. “Some people call it shape-memory. When we react these flexible materials with high-refractive index hard materials, the film gains impact resistance.”
Typically, increasing display brightness decreases durability. That’s what Gerrad and Bryan solved.
“It’s amazing to be able to combine two properties that should not work together,” explains Gerrad. “The invention here is reacting the hard materials that give us the brightness with very flexible materials, like a rubber ball, in a way that the final film could compress and come back to its original shape and durability.”
In this case, brightness is recovered. But, how? The prism technology in the brightness enhancement film collimates and redirects light back toward the viewer by bouncing the light off angular surfaces. This ultimately helps enhance the brightness of your display.
“It is used in the backlight of an LCD display to redirect the light from where you don’t really care where it’s located, which is usually away from you, and back to the location where you are looking at the display,” explains Gerrad. “That unused light is now used in an appropriate way, and we can also use that light to enhance the efficiency of the device.”
The prism film is able to help the battery of your phone last longer – something that is especially important as we continue to depend on battery efficiency to complete the majority of our work on tablets, notebooks and smartphone devices.
“We used to rely on desktop computers and things that were plugged in to do most of our work. Energy efficiency is important for these devices, but not nearly as important as when you have a mobile device with you as you travel and as you work,” says Gerrad. “Instead of having to use more battery power to provide the brightness the viewer wants, the efficiency provided by our films lets us provide brightness with less power, saving energy and helping your phone’s battery last longer.”
The scientists use a lightbox to measure transmission of light in displays.
“When we’re looking for optical defects on our prismatic film, or any of our other optical films, we’ll put them on a lightbox to simulate the liquid crystal display (LCD) itself. We’re able to see how light gets transmitted through those films in order to identify defects and areas for improvement,” says Gerrad.
Gerrad predicts that the technologies inside our smartphone displays will continue to change. “I expect microreplication, like all things, to get smaller,” says Gerrad. “Eventually, we’ll start to see smaller and smaller structure sizes and ways that we could use those new types of structures and new materials together, to make even brighter displays.”
His team is already working on the next solution.
“We’re helping to enable slimmer, more robust devices, so people can take them wherever they want without having bulky protective cases.”
Curiosity is at the center of this innovation – a curiosity that began long before Gerrad and Bryan started working together at 3M – and a curiosity they encourage our next STEM generation to embody.
“My curiosity stems from wanting to take things apart and understand how things work. Electronic devices have always been my passion, so disassembling the latest gadget is always something fun for me to do,” says Gerrad. “It’s important for young people to be curious about the world around them, because they need to understand how the world works and how they themselves can make improvements to be agents of change.”