Making the active stylus better without batteries

NFC allows the traditional active stylus to be self-powered and do more.

The active stylus is due for an upgrade, and it is currently being ripped apart and completely redesigned and rebuilt to make it more functional and address user complaints.

Some of the issues surrounding active styli – according to Shwetank Kumar, director of touch engineering within Intel’s human interface technology group – are batteries running out of charge, lack of consistency between stylus manufacturers, the and the stylus technology being proprietary, meaning styli are tied to a single type of device. Often stylus manufacturers work with display OEMs or ODMs to ensure their active stylus technology is baked into the screen.

At Intel, engineers are working to develop a next-generation active stylus, one that eliminates the need for a battery to power it and uses NFC as the core component.

Near field communications (NFC) has long been a part of computers, tablets and many smartphones. It allows for very low-powered communications between devices and even objects where an NFC chip is embedded. It is used in smart bathrooms and was part of CES badging, for example. Having a small but powerful size, many unique use cases are popping up to bring better and different functionality to existing products.

A tablet modified to work with an NFC stylus

A tablet modified to work with an NFC stylus

Typically, NFC-enabled devices like tablets, kiosks and computers are destinations, says Anand Konanur, a senior radio frequencies engineer within Intel’s PC Client Group. When a user taps against a kiosk, they get a visual response of the action. With a PC, the NFC coil, which measures 4 cm by 6 cm, is typically somewhere on the back of the display.

Konanur and his team realized that users wanted to tap their NFC devices directly against the screen and not on the back of their computer so his team wanted to get what he calls “NFC-friendly” screens where the magnetic signals pass directly through the display.

Konanur believes NFC incorporated into the front of the display screen instead of the back of the device can be used for a variety of other tasks like communicating with small devices and even charging these devices. Previously, displays were thicker with a large metal casing but more recently, the metallic deflector sheets that are used to maintain brightness are being replaced with non-metallic sheets, opening up the ability to have NFC coils directly within the layers of the displays.

NFC circuitry that can function through the LCD display

NFC circuitry that can function through the LCD display

Once Konanur and his team had displays with NFC coils behind the screen, they set out dissecting active styli, stripping out much of the circuitry and the AAAA battery. An AAAA battery holds a 1.5 volt charge and is typically thinner than the more common AAA battery. The premise of the work undertaken by Konanur was that a simpler system would cost less to manufacture while also potentially providing additional communication abilities. The initial ripping apart and retrofitting of NFC technology in the device is only the first step toward a complete overhaul and redesign of the active stylus.

“We started off trying to replace the battery just to make it cheaper and also to let this anxiety from people go away that they will lose their stylus in the middle of something important and that it will get discharged,” says Konanur. “How do you know that you will always obtain power as required?

“But in doing so and also using NFC, we realized that you can add a communication link between the stylus and the PC,” says Konanur. “You can pre-program the stylus to act as a particular way, you can pair a stylus with a PC. There are things we can do now with storing little bits of information in the stylus.” Konanur said with the few kilobytes available in storage on the NFC stylus profiles, different user preferences, configurations or other types of data could be stored potentially.

An NFC stylus that's able to charge wirelessly from the tablet

An NFC stylus that’s able to charge wirelessly from the tablet

Other benefits to NFC-powered styli include a more environmentally friendly design with the elimination of battery recycling as well as a more open standard for application developers and industrial designers. Konanur also believes that with the gained space within the stylus, other sensors could be added to make the stylus more of a stand-alone device to augment the functions of the PC, or to provide additional functionality when coupled with computer algorithms.

Challenges still exist, however, according to Kumar and Konanur, specifically around larger displays as well as ensuring the NFC-powered stylus has active power immediately with no perceptible delay. While smaller, 7- to 8-inch screens on tablets can use a single NFC coil potentially, larger form factors may require other types of solutions such as having multiple NFC coils behind the screen in various locations or charging a stylus when it is contained within the device, which could also require a small, rechargeable battery or a super capacitor, says Kumar.

“I think the pen is a very important aspect of the user experience on tablets, which has so far been largely ignored or slapped together through some combination of what ecosystem players have been able to do themselves,” says Kumar. “There really should be no reason in this day and age that you have to carry a paper and a pen anymore, you should just be able to use an electric pen across the board on different devices.”

“At the end of the day, a stylus can be a very finely crafted instrument,” says Konanur. “It’s probably a computing device in its own right.”

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