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September 18, 2015

What led to the Universal Stylus Initiative

A short while ago I received a press release from the Universal Stylus Initiative. I filed that away in my mind, but got back to it because the concept certainly sounds interesting. Having used, described, tested and compared numerous pen and touch technologies over the past two decades in my work first at Pen Computing Magazine and then at RuggedPCReview, I definitely consider it a relevant and increasingly timely topic (witness Apple's announcement of the iPad Pro with a pen!).

So I spent some time thinking things through and figuring out the need for a universal stylus initiative.

The great appeal of tablets and smartphones, of course, is that they provide tremendous communication and computing capability in small and handy packages that can be taken anywhere. That's in part possible because they don't have physical keyboards that add weight and get in the way. The trade-off, of course, is that without a physical keyboard and a mouse it isn't as easy to enter a lot of data or easily operate the computer.

That's where touch and pens come in. Early tablets (yes, there were tablets in the early 1990s) were called pen computers because that's how they were operated, with active pens. There was touch, too, but it was primarily of the resistive variety that worked best with a pointy stylus. That technology saw its heydays when phones were still dumb and people kept their address books and calendars first on Apple Newtons and then Palms and Pocket PCs.

When Microsoft became interested again in tablets around 2001/2002 (I say "again" because they'd been interested a decade earlier, but primarily to fend off pen-based rivals to Windows) they built the "Tablet PC" around active pen technology. It's called "active" technology because a sensor board behind the LCD detects the precise position of the tip of the pen even when the pen does not actually touch the glass. That's different from "passive" touch technology where a touch is only registered when a finger or stylus touches or depresses the LCD surface.

What are the inherent advantages and disadvantages of active versus passive?

First, active pens make "hovering" possible. That makes it possible for a cursor to follow the pen without actually registering a touch. This way, the user knows where the tablet sees the pen. That allows for very precise operation, just like it is with seeing the cursor when one operates a mouse. Second, active pens can be pressure sensitive. That can be used for 3D-like operation, and is invaluable for artists and designers. Third, active pens can have very high resolution, which makes them quick and very precise, something that's increasingly important on today's super-high resolution displays. On the negative side, active pen technology is fairly expensive. It can be inconvenient to have to first locate the pen before the tablet is operational. And if the pen gets lost, the device may become unusable.

And what about the pros and cons of passive touch technology?

The good thing is that conventional resistive touch doesn't need a special pen. Any cheap stylus will do, as will a fingernail and even firm finger touch. Resistive touch is also fairly precise as long as it's used with a stylus, and it's totally immune to rain or any wetness. For that reason alone, many rugged tablets and handheld computers have been using resistive touch for many years, and are still using it. But passive resistive touch has some significant disadvantages as well. Finger touch alone is very imprecise and unsuitable for operating small user interface components such as scrollers, check boxes and the like. Even when using a passive stylus, there's no cursor to tell you where exactly the touch will be registered. And there's the issue of "palm rejection," i.e. making sure that the device only reacts to the stylus and not only to inadvertent contact via the palm of the user's hand.

The above was roughly the status quo until Apple popularized projected capacitive multi-touch with the iPhone. Procap, or p-cap, as it's commonly referred to, is still passive touch. But it's a far more refined and much more elegant type of passive touch. Instead of pushing down hard enough to register a "touch," p-cap works via "mutual capacitance," i.e. the decrease in capacitance between a sensor electrode and a drive electrode when a finger gets close enough to affect (syphon off, really) the normal capacitance between a pair. This technology only requires a very soft touch, and it's quite precise once a user gets the hang of it. It's also quick because it's electronic rather than physical, and p-cap can easily recognize more than one touch at the time. Apple took advantage of all of the advantages to allow the effortless tapping, panning, pinching and zooming that not only made the iPhone a game changer, but also made p-cap the touch interface of choice for virtually all tablets and handhelds.

However, even the wonderful p-cap technology has its disadvantages. First, the subtle change in capacitance between two electrodes when a finger touches it requires a dry surface. Water, with its great conductivity, tricks the electrodes into false readings. Second, since p-cap also doesn't facilitate "hovering" and the finger touch area is fairly large, p-cap operation isn't nearly as precise as that with a mouse or an active pen. Neither of those advantages was severe enough to keep p-cap from becoming the success it is. They were, however, the primary reason why some tablets and even phablets became available with active pens. And that even though the late Steve Jobs was adamantly opposed to pens.

There is, unfortunately, no getting around the fact that legacy Windows doesn't work well with p-cap. One result of that recognition was Microsoft's bafflingly unfortunate Windows 8 that imposed not-ready-for-primetime touch functionality to all the hundreds of millions or billions using legacy Windows software on the job. Another was that, Jobs' decree notwithstanding, tens of millions bought Samsung's Galaxy Note tablets that combined p-cap with a little Wacom pen, adding precision when needed, and also a handy tool to jot and draw and doodle.

How did all of this affect the industrial and vertical mobile computing markets we cover here at RuggedPCReview? In a number of ways.

While p-cap totally took over on consumer smartphones, it took years for rugged handhelds to switch from resistive touch to p-cap. That's for two reasons.

First, Microsoft simply didn't provide an upgrade path to Windows Mobile, Microsoft's mini-OS that had dominated industrial handhelds for many years. The p-cap-friendly Windows PhoneOS was for consumers, and so Windows Mobile, although at some point renamed Windows Embedded Handheld, became a dead end. With the result that while smartphones charged ahead, vendors of industrial handhelds were stuck with an increasingly obsolete OS. In the consumer smartphone market, Android quickly filled the void left by Microsoft, but industrial and vertical market customers were, and still are, much slower to adopt Android.

Second, vertical market customers often do wear gloves and they often have to work in the rain or where it gets wet and p-cap doesn't work well. Between these two reasons, staying with resistive touch and a passive stylus made sense.

The situation, interestingly, was different with tablets. While the capacitive touch-based iPad was a runaway success that was followed two or three years later with equally successful Android tablets that also use p-cap, Android had a much harder time in industrial and vertical markets. There were a good number of attempts at industrial and enterprise Android tablets, and some saw modest success. But on tablets the pull and advantages of remaining part of the established Windows infrastructure were much stronger, and Windows tablets saw, and see, remarkable success. To the extent where not only the majority of vertical market tablet vendors continue to offer Windows tablets and introduce new ones, but where Microsoft itself is heavily investing into its own Surface tablet hardware.

Which, of course, gets us right back to Windows' weakness with pens. Microsoft's very own tablets use active pens in addition to p-cap, in essence admitting that even when using Windows 10, finger tapping alone just won't get the job done.

So we're sort of back to the same predicament pens had a couple of decades ago. Extra cost, easy to lose, proprietary. You can use any pen or pencil to write on any piece of paper, but a Wacom pen will only work with a Wacom-based tablet, an nTrig pen needs an nTrig tablet, and so on. And none of those proprietary pens could be used on a regular p-cap phone or tablet.

And this, finally, gets me to the Universal Stylus Initiative (USI). USI is a non-profit that was formed in early 2015 specifically with the goal of creating a standard that would allow any active pen to work on any p-cap smartphone, tablet or notebook.

On September 10, 2015, USI announced that their membership had grown to 31 companies, more than doubling from the initial launch in April 2015. Initial membership included such touch/pen heavyweights as Wacom, Atmel, Synaptics, eGalax-eMPIA, Hanvon Pentech, Waltop, as well as electronics industry giants Intel, Sharp, and Lenovo. By now, Asus and LG joined, as well as stylus providers (KYE Systems, Primax, Solid Year Co, Montblanc Simplo), and touch controller providers like Parade Technologies, Silicon Integrated Systems, Raydium Semiconductor and STMicroelectronics International.

This immediately brought up the question as to why any vendor of active pen systems would want to have any part of such a thing. After all, these are technologies heavily covered and protected by iron-clad patents and unassailable intellectual property. And the market for (rather expensive) replacement pens is quite profitable.

A visit to USI's website (see here) answered a few questions but not all, as the specification and most of the background technical information, of course, is only available to USI members.

I was fortunate that USI Chairman Pete Mueller made himself available to a much appreciated call. Pete, whose daytime job is that of principal engineer and senior technologist at Intel, explained that while there is indeed extensive intellectual property in active pen technology, the major players in the field have long seen the potential strategic advantage of providing a degree of interactivity. Talks between them are not unusual as making active pen technology more universally desirable will likely result in a much larger market. (Note that earlier in 2015 Wacom announced a "Universal Pen Framework")

Think about it: there are by now billions of p-cap smartphones and tablets without active pens. Given the increasing call for productivity-enhancing (i.e. creation, analysis, design, etc.) rather than activity-draining (i.e. news, video, silly cat tricks, games) smartphone and tablet technology, the availability of universally compatible pens might be a massive boon. Unlike today where the only option for tablet users are those awful fat-tipped passive pens that are hardly more precise than fingers, a universal active pen could open up entirely new functionality for little or no extra cost.

Atmel's blog quotes Jon Peddie of Jon Peddie Research as saying, "To date the market has been limited by proprietary touch controller-stylus solutions, which limits OEM choices and cost reductions. With the USI specification released, we expect that the capacitive active stylus market will grow from 100 million units in 2015 to 300 million units in 2018, opening up new markets such as smartphones and all-in-one PCs (see quote here).

How does USI intend to make that possible? In their words, "the USI standard defines the communication method by which the stylus sends data about the stylus operation to the smart phone, tablet or notebook PC. The data includes information such as pressure levels, button presses or eraser operation. In addition, USI technology makes use of the existing touch sensor (via a technology called Mutual Capacitance) in smart phones, tablets and notebook PCs, so that the added cost for enabling USI technology on these devices is zero or minimal."

But if we're talking active pens working with capacitive touch controllers, how could those p-cap controllers possibly work with active pens? Pete couldn't go into details on that because much is non-disclosure material, but the general idea that I got was that using a "USI-enabled" pen on a "USI-enabled" device would provide some, but not all of the full functionality of a particular active pen technology.

What does that mean? A look at original USI member Waltop's website provides some clues. It says that they provide both USI-enabled and vendor-specific styli, and that both types "satisfy the performance requirements of Windows 10, such as accuracy, linearity, latency, hovering height, etc. So presumably the USI standard seeks to cover all the mandated basics of using an active pen on a p-cap touch screen, but there are still special capabilities, extra functionality and perhaps higher performance only available through the full proprietary active pen technology. To use one of my beloved automotive analogies, USI provides the road system that allows any street-certified vehicle to get from point A to point B, but if someone has special desires and requirements, they will still want to get a Lexus or a Porsche.

However, Atmel's blog says that Through the same sensor that one’s finger uses to command a device, the stylus communicates via different frequencies to perform the action of writing — writing with up to 2048 different levels of pressure to give the pen-on-paper experience and render thinner or thicker lines in note-taking, painting and doodling, just like an ink pen." That sounds more like some of the proprietary functionality of an active pen system is being brought over into USI-spec passive p-cap controllers.

Poking around the web a bit, it seems like USI systems will be able to differentiate between a USI mode and a proprietary mode, or even switch between the two, depending on which seems appropriate. USI pens apparently will be AAAA battery-powered allowing a slender size and a projected 12-month battery life.

As is, USI hopes to have version 1.0 of their specification done by the end of 2015, and after that we should start seeing active pens that work on any p-cap device that's also compliant with the USI spec. It should be interesting to see what will become available, how well it works, and whether the initiative will take. -- Conrad H. Blickenstorfer, September 2015


  • Website of the Universal Stylus Initiative
  • The Universal Stylus is Coming (Intel Free Press)
  • Universal stylus to bring easy digital inking to tablets (TechRadar)
  • Early example of a USI pen: Baton US-70

    Posted by conradb212 at 05:47 PM | Comments (0)