New pressure sensitive multi-touch technology may make its way to the iPhone, iOS 9

One of the key control elements of Apple, Inc.'s (AAPL) smartwatch is its Force Touch technology.  The technology has also made its way into the new 12 inch Macbook and the refreshed MacBook Pro models.  Now another report offers a more detailed description of how sources say iOS 9 will make use of Force Touch, in preparation for the ninth generation iPhone's arrival later this year.

I. The Road to Force Touch

In the modern era capacitive multitouch smartphones have become ubiquitous.  Apple holds the distinction of being the first company to successfully commercialize this form of multitouch in the smartphone.  Now, it's worth noting that other companies had previously commercialized resitive multitouch, but at lower sales volumes.  And capacitive multitouch's fundamental principles had been laid out mostly in the 1980s in university publications. However, Apple was the first to commercialize to seize upon the more promising capacitive flavor of touch multi-finger touch technology.

Neonode N1
The Neonode N1 was the first major multitouch device, but it used a slightly different implementation of the technology that relied upon resistance, not capacitance. [Image Source: Engadget]

In terms of intellectual property, most of Apple's multitouch "innovation" actually came second hand via an acquisition.  In 2005 Apple's late CEO Steve Jobs cleverly scooped up FingerWorks, a prescient pioneer of multi-touch heuristics.  Founded by University of Delaware Professors John Elias and Wayne Westerman the time FingerWorks was using its capacitive multi-touch to produce touch keyboards commercial for PCs.  Jobs saw that the technology held more promise in the mobile device space, where lack of tactile input (e.g. keyboards and mice) and space constraints were driving the adoption of novel control technologies.


Once Apple showed the potential of the technology in the mobile space -- something only a few resistive touch pioneers such as Neonode saw -- Apple's rivals moved swiftly to adopt the technology, finding ways to avoid the minefield of Apple's heuristic patents (most of which came courtesy of the FingerWorks acquisition).  Ultimately, while Apple controlled the firmware, it never directly produced the touchscreen.  In fact, it relied on rivals like LG Electronics Inc. (KRX:066570)(KRX:066575) and Samsung Electronics Comp., Ltd.'s (KRX:005930) (KRX:005935) to mass produce the multitouch screen hardware that went into its devices.

Samsung and LG (and their client rivals to Apple) did the logical thing of embracing the technology.  And with a ready source of hardware, they were able to subtly change the firmware implementation from Apple's to largely avoid patent infringement claims.

iPhone Touch

The 2007 iPhone vaulted multitouch onto the global stage. [Image Source: How Stuff Works]

Today Apple and its rivals' multitouch is effectively the same at the hardware level.  It consists of a grid of transparent sensing lines laid atop of a glass substrate with a protective layer over top.  The capacitive part comes from the fact that sensing is driven by the charge stored on the capacitor grid is dissipated when a finger touches, allowing for algorithmic detection of the position of one or more fingers on the screen.

II. Force-Sensing -- Extending the UI

But multitouch only gives a single piece of data -- position.

To extract more information there's a couple of common routes you might take.  You could detect the proximity, which would allow for a secondary set of "hand near screen" gestures.  (Or in the simplest implementation a "hand is near" type wakeup.)  Samsung uses this technology in its Galaxy smartphone firmware.  Microsoft Corp. (MSFT) also toyed with this idea under the billing "3D touch" with its "McLaren" phone prototype, but the project was ultimately shelved amid disappointing results.

A second route, which has largely been overlooked in the mobile space is pressure-based touch.

Force Touch is sort of a garbage bin term it appears for Apple.  In the MacBook version Apple has been showing a four-sensor layout of force sensors below the capactive glass layer:

Force Touch

Apple Force Touch

iFixit's teardown reveals that Apple is using four strain gauges -- four electromagnets that push and pull on a common rail (seen as the copper town middle element above).  This configuration makes sense for a trackpad, as it both provides a click-type movement/response and it senses the force in the process.

The Apple Watch's version of Force Touch is more binary and quite different in implementation.

Deformable array

Apple's Watch product page describes:

Force Touch uses tiny electrodes around the flexible Retina display to distinguish between a light tap and a deep press, and trigger instant access to a range of contextually specific controls.

Apple Watch touch

This lines up closely with Apple's U.S. Patent No. 20120242592 A1 which describes:

[A] tiny electrodes around the flexible Retina display to distinguish between a light tap and a deep press...

The key to the patent is to make the protective top layer and the capacitive touch layers flexible, which allows them to strike or otherwise alter the electrical profile of a submerged grid of electrodes that essentially lay in shallow wells in a grid beneath the protective and capacitive touch layers.  It takes a bit of force to deform the flexible display, so you know this is a stronger strike, and hence intended to trigger a different action.

Apple Force Touch -- mobile
Apple's patent suggests the electrode array lies beneath the protective and capactive multitouch layers. [Image Source: Google Patents]

Apple's patent description describes numerous electrode designs, so it's unclear exactly how it's implementing these tiny submerged switches, but most implementations use the well approach, so that much is known (or probable, at least).
Apple Force Touch
Apple's flexible Force Touch patent describes a variety of electrode well implementations.
[Image Source: Google Patents]

It's very important, however, to note this is wholly different in practice from "Force Touch" on pen-style art tablets or the Mac Trackpad, as it's boolean (on/off; 0/1) rather than fractional (normalized on 0.0 to 1.0).

III. Coming Soon to an iPhone Near You

In March The Wall Street Journal reported that Force Touch of boolean variety (as seen in the Apple Watch) would be coming to the iPhone, likely via the ninth generation model, which launches later this year.  WSJ columnist Lorraine Luk reported:

Apple Inc. plans to add sensors to detect how hard a user is pressing on a screen to its next iPhones, incorporating a technology used in its forthcoming MacBook and Apple Watch, according to people familiar with the matter... The touch technology is one of the changes that Apple plans for the next versions of its iPhones due for release later this year, these people said.

The WSJ report gave a hypothetical example that the technology might allow for greater accurate in electrical piano apps.

iOS 9
[Image Source: iOS 9 Guide]

The fresh report published this week by 9to5Mac asserts that Force Touch is still on the docket for the upcoming iOS 9 OS/firmware/core apps release, with hardware support to be added via the ninth generation iPhone.  The report reveals some potential ways the technology will be applied to the core apps in iOS writing:

Force Touch will be integrated into Maps to drop new pins, into media players for pressure-sensitive scrolling, into the Calendar for adding new events, and across the system for quickly looking up word definitions, according to sources who have used Force Touch on prototype versions of the "iPhone 6S."

Much like proximity sensing, boolean flexible Force Touch may offer a novel, if a bit gimmicky extension to the traditional smartphone multitouch equation.  We should see an Apple Watch-like electrode version of Force Touch in the ninth generation iPhone, plus potentially in a rumored sixth generation refresh of the iPod Touch line that's been overdue for some time now.

That said, it does not appear that Apple will be ready to deploy a far more impressive future technology -- variable force detection.  That's a far more daunting challenge.  Consider that Wacom Comp., Ltd. (TYO:6727) et. al. house the pressure sensing mechanical sensor inside the pen.
Wacom pen schematic
A Wacom pad houses its pressure sensor in the pen device. [Image Source: Wacom]

And the MacBook version relies on electromagnetic strain gauges mounted to the trackpad to give a natural clicking type motion.  A smartphone would likely have to use something different and more complex as it doesn't naturally have a click-style motion.

A possible solution being consider by Apple, Samsung, and others is likely a more highly flexible display layer paired with a more sensitive grid of electrodes capable of detecting multiple levels of touch pressure.  We'll have to wait -- perhaps half a decade or more, likely -- to see that level of sensor sophistication be achieved in the mobile space, though.  For now technologies like Samsung's proximity sensing and Apple's boolean mobile Force Touch are the next best "dumbed down" way to go a bit beyond traditional multitouch.

Source: 9to5Mac

"I mean, if you wanna break down someone's door, why don't you start with AT&T, for God sakes? They make your amazing phone unusable as a phone!" -- Jon Stewart on Apple and the iPhone

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