Silver ring around 'iPhone 5S' home button may be integral to fingerprint reader, not just for looks

Posted:
in iPhone edited January 2014
Reports on Friday spurred talk of a "silver ring" that will supposedly adorn the "iPhone 5S" home button, though a look at the technology driving Apple's AuthenTec sensors suggests the part is more important than just window dressing.

HomeA component claimed to be Apple's "iPhone 5S" fingerprint scanner. Picture via Sonny Dickson.


Apple is widely expected to launch a next-generation "iPhone 5S" at a Sept. 10 media event, with rumors and parts leaks pointing to the inclusion of a fingerprint sensor embedded in the device's home button.

While numerous reports have tried to guess what purpose the biometric sensor will serve, other than obvious security functions, and how it will work, few have investigated the technology itself. Doing so not only yields clues into possible use scenarios, but answers usability and design questions. Like those regarding the silver ring.

Clayton Morris of Fox News first mentioned the supposed shiny home button flourish last month on an episode of This Week in Tech, better known as TWiT. Morris proposed the ring is merely aesthetic, possibly added so users can easily distinguish an iPhone that has a built-in fingerprint sensor from those that do not.

However, taking a look at previous patent filings unearthed by AppleInsider, the metallic ring may be a functional component necessary to the sensor's operation.

There stands a variety of ways to accomplish biometric fingerprint readings, including the stereotypical "swiping" motion made famous in movies, as well as methods using optical, thermal, pressure and capacitive measurements, among others. AuthenTec, which Apple purchased in 2012 for $356 million, uses a few different capture methods in its products, though the tech most likely to be used in the iPhone doesn't involve swiping.

Typical methods of swipe authentication, usually direct capacitance, involve a thin "strip" sensor that captures and stitches together multiple images of a fingerprint as a user sweeps their finger across the sensing plate. With direct capacitance, an electrical field is applied to the sensor, which detects ridges and valleys ? the skin structures that form fingerprint whorls ? by measuring variations in capacitance at the sensor plate. Lower capacitance denotes skin that is farther from the sensor, or valleys, while higher capacitance is associated with ridges.

Smart Sensor
Cross section of AuthenTec's Smart Sensor with RF field technology.


A more accurate and robust method of capture is called radio frequency field sensing, or AC capacitance. Like direct capacitive sensing, this technique also measures capacitance of a sort, but the similarities end there. Instead of measuring the effect on an electrical field, a low frequency RF signal is inserted into the finger and received by the sensor. In this case, RF signal strength captured by the pixel traces are measured and the corresponding data is translated to form an image of the print.

Benefits of RF field/AC capacitance sensing include static non-swipe readings, resistance to dust and capability for the sensor to operate even when covered by layers of protective material. These types of sensors are usually larger in size to allow for a wider capture area.

One patent, filed by AuthenTec cofounder Dale R. Setlak and subsequently assigned to Apple, goes into detail about a technology based on mechanics which are very similar to RF field sensing. The property also relates to the company's "Smart Sensor" ? also based on RF field sensing tech ? which has been used successfully in at least one phone, the Japan-only Toshiba REGZA T-01D.

RegzaToshiba's REGZA T-01D smartphone with AuthenTec sensor. Note gray driver ring around sensor array.


As noted in Setlak's patent, along with other similar inventions credited to his name, electrodes need to be in contact with the finger to pump the drive signal that will ultimately be measured by pixel traces on the pixel plate.

In nearly all RF field sensors, a ring disposed around the sensor array acts as the electrode that drives the low frequency RF signal into the finger, which is attenuated by ridges and valleys in the print and finally captured by AC sensors as a high quality image.

Fingerprint Sensor
Illustration from Setlak's patent showing a pixel trace sensor array.


As a type of bonus side effect, the tech can also be used as a form of input. By analyzing slight movements or changes in attenuation over time, the system can interpolate gesture behaviors like scrolling, cursor control and, when combined with a physical or virtual button, drag-and-drop operations.

Embedding this type of package in an iPhone's home button is likely quite challenging as the part moves up and down constantly, which would put undue wear on the sensing module's interconnects. It is possible that Apple has found a way to separate the finger ring from the sensor array in order to isolate the integral components from wear and tear. Such a system would also be less apt to fouling or misreadings due to debris.

As for utility, the sensor design wouldn't force users to swipe the home button to authenticate, but would have the module read the print while a user presses the button to wake the phone from sleep. In other words, the security factor would take place seamlessly. No new gestures to learn, just enhanced functionality, transparent to the user.

It remains wholly unknown if Apple has incorporated this particular fingerprint technology into the next-gen iPhone, though circumstantial evidence seems to point in that very specific direction.

Further, a non-functional aesthetic bezel rimming the home button, which has seen nary a design tweak since the first iPhone launched in 2007, simply to demarcate new biometric capabilities seems to go against Apple's design sensibilities. When the company introduced a front-facing camera with the iPhone 4, it buried the feature just above the earpiece. No special decorations or embellishments to note that the handset sported FaceTime capabilities.

In any case, all should be revealed at Apple's Sept. 10 special event, at which the company is widely expected to unveil a next-generation iPhone. With or without a fingerprint sensor.
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Comments

  • Reply 1 of 35
    dugbugdugbug Posts: 283member
    Damn nice writeup
  • Reply 2 of 35

    You're totally right. This Dell laptop I'm using has an Authentec TouchChip TCS1 and it doesn't work unless you're touching the bezel ring. Never noticed it in the 2 years I've used it before.

  • Reply 4 of 35
    Great reporting AI! That is an outstanding presentation of facts supporting a conclusion that seems fairly plausible.
  • Reply 5 of 35
    shogunshogun Posts: 362member
    Nice article. Very plausible. Thanks
  • Reply 6 of 35
    I remember something about liquid metal a few months ago.
    Could this be the reason to make sheets of liquid metal?
  • Reply 7 of 35
    gtrgtr Posts: 3,231member
    I'm unsure exactly how I'll feel giving my iPhone the finger every time I want to use it...
  • Reply 8 of 35
    asciiascii Posts: 5,941member
    Quote:

    Originally Posted by AppleInsider View Post



    Further, a non-functional aesthetic bezel rimming the home button, which has seen nary a design tweak since the first iPhone launched in 2007, simply to demarcate new biometric capabilities seems to go against Apple's design sensibilities.

    I agree, they never just stick things on for appearances, there's always a purpose behind each part.

  • Reply 9 of 35
    Quote:

    Originally Posted by ascii View Post

     

    I agree, they never just stick things on for appearances, there's always a purpose behind each part.


     

    On the other hand they could have painted or anodized the ring black. It's brown colored on my Dell to match the chasis.

  • Reply 10 of 35
    Great job Mikey! Extremely well written and informative!
  • Reply 11 of 35

    Glad you enjoyed it!

  • Reply 12 of 35
    If the fingerprint sensor works successfully watch every Android smartphone manufacturer attempt to duplicate it. I hope Apple patented everything that has to do with the software controlling the fingerprint sensor. As it is, Samsung will simply reverse-engineer the sensor and come up with a better and cheaper sensor like they do with every other piece of hardware they get their hands on. This fingerprint scanner will be claimed by the pundits that it's not innovative enough because other companies like Motorola have already attempted it and failed.
  • Reply 13 of 35
    Really well-written article. Much more balanced than Daniel Eran Dilger.
  • Reply 14 of 35
    sockrolidsockrolid Posts: 2,789member

    The ring could be razor sharp steel.  You cut your fingertip and deposit blood on the sensor.  

    It scans your DNA, et voila, your iPhone is unlocked.  More accurate than fingerprints.  :-)

     

    And, while we're being all Looney Tunes, if there's also some kind of RF function, could

    that same sensor multitask and  be used for RFID?  And/or NFC?

  • Reply 15 of 35
    rogifanrogifan Posts: 10,669member
    You think? Why in the world would Apple now decide to add a sliver ring around the home button for no reason?!?
  • Reply 16 of 35
    19831983 Posts: 1,224member
    Quote:


     As a type of bonus side effect, the tech can also be used as a form of input. By analysing slight movements or changes in attenuation over time, the system can interpolate gesture behaviours like scrolling, cursor control and, when combined with a physical or virtual button, drag-and-drop operations.


    This potential functionality reminds me of Blackberry's nipple touch-pad on their keyboard smartphones. RIP 

  • Reply 17 of 35
    flaneurflaneur Posts: 4,526member
    gluben wrote: »
    Really well-written article. Much more balanced than Daniel Eran Dilger.

    I agree with the first sentence. The second shows that you, along with many others here, don't get Dilger's M.O. He isn't motivated by the nuts and bolts of the technology so much, but the grand machinations, especially where there's conflict involved. Apple's existential struggle, and all that.

    You won't see Gruber trekking down to Maiden N.C. to see the data center going up, for example. Or Philip Elmer-DeWitt checking out the demolition of the HP buildings in Cupertino. Every writer has his interests and his demons, the question being do we learn something useful from them.

    Then again, I've sometimes thought that Mikey Campbell is an alter ego of Daniel Eran Dilger.
  • Reply 18 of 35
    flaneurflaneur Posts: 4,526member
    gtr wrote: »
    I'm unsure exactly how I'll feel giving my iPhone the finger every time I want to use it...

    They'll sell millions more if Siri can tell you that you're pressing too hard.
  • Reply 19 of 35
    Siri: Rub your finger harder Dave.

    Dave: Rubs harder.

    Siri : Ah, yes Dave , yes!!
  • Reply 20 of 35
    And at the presentation this will be the spiel: "The iPhone 5S. The "S" stands for 'security'..."
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