How the technology behind Apple's Touch ID will likely change with 'iPhone 8'

Posted:
in iPhone edited April 2017
There's a lot of talk about Apple's shift to a new screen technology with the "iPhone 8," but fewer conversations about how it will all work -- AppleInsider explains what changes Apple will likely need to make to implement the technology, while retaining Touch ID on the front of the rumored edge-to-edge screen on the device.




A rumored shift to an OLED screen in the "iPhone 8" changes the game -- not just for battery life, but for related technologies. Apple has had a great deal of success with the best-in-class fingerprint reader technology that it has used since the iPhone 5s, but unless it's moved to the back of the phone, the underlying sensing technology needs to change.

As it stands with the iPhone 5s through the iPhone 7, the Touch ID technology developed by AuthenTec senses the presence of a finger with a detection ring which switches on the sensor when it detects a digit. The sensor itself is clad in a thin sapphire crystal, and uses a complimentary metal oxide semiconductor capacitive touch sensor to detect the fingerprint's whorls and ridges with 500 pixels per inch resolution.

The captured fingerprint is then passed to the Secure Enclave and compared to stored data local to the phone. Should the mathematical models match, the phone is unlocked.

There are two major revisions of Touch ID, with the only real difference being sensing speed in more recent version on the iPhone 6 and iPhone 7 families.

So where's the problem?

The problem lies with the difference in thickness between the sapphire lens and the sensor. The sensor itself is 170 microns thick, with the sapphire lens not that much thicker.

While an OLED screen assembly is thinner than that of a comparative LCD display, the glass cover is about the same thickness between the technologies. At just less than 1 millimeter thick, the screen glass is over five times the thickness of the sapphire lens on the existing Touch ID sensor on the iPhone 7.

With fingerprint sensors used in Touch ID, as separation between the contact surface where a user places their finger and the capacitive sensing array increases, there is a corresponding blurring of the finger's electric field captured by the Touch ID sensor. In the existing Touch ID implementation, the lens is sufficiently thin that any distortion, or aberration, is minimal.

When a sensor is placed behind a thicker lens, in the case of the "iPhone 8," behind the screen glass itself, the inevitable blurring without some form of correction can lead to degraded fingerprint image resolutions and decreased recognition accuracy.




Math can be used to determine exactly how much distortion would be introduced with thicker glass -- but it is extremely complex and to figure it out precisely would require more data about the optics of the sapphire Touch ID cover than is currently known. However, roughly speaking, the aberrations induced between Touch ID now, and if it was embedded behind much thicker screen glass would increase between 5 and 15 times what is expected now.

If Apple compensated in software for that and allowed for more fingerprint variation between what is stored and what is sensed, it would make Touch ID much less secure. This would likely be unsatisfactory for the banking industry, and would impact Apple Pay.

However, Apple has a patent for a touch sensor using an array of electrostatic lenses. By using the lenses in between a designated touch area and the sensor behind the thicker glass, the electric field associated with a user's finger can be presented undistorted -- or less distorted -- to a sensor embedded in the glass.




Apple has to perfect this, before the Touch ID can be embedded under glass. Perfection must extend to manufacture of the sensor, as well.

Nobody said that this would be easy

Optics on a macro scale in a telescope aren't quite the same as on a micro scale in Touch ID -- and make no mistake, a microscopic scale is what we're talking about with the iPhone's implementation of Touch ID. Differences in microns can make all the difference between accuracy and security of the system, or one that doesn't work well at all.

Apple says that the probability of matching a Secure Enclave stored fingerprint is 1 in 50,000 for one enrolled finger -- and this is where it needs to stay, with no slop making it easier to unlock or spoof with a fake finger gleaned from a fingerprint left someplace else.

There are recent reports suggesting that Touch ID is what may hold up the shipment of the "iPhone 8," but not the reveal. There are more claiming that the sensor may get relocated to the back of the device, but given the flak that the Samsung Galaxy S8 is taking for having done so, that may not be the case either.

The road to Touch ID and a virtual home button under a front screen glass was paved with the solid state button on the iPhone 7 family. The technology is crucial to Apple's services, as it is a key underpinning of Apple Pay -- to say nothing of cryptological protection of a user's data living on the phone.

Cook and company don't ship a product until they feel that what they've developed is the best that they can make it, for the widest user base, and as safe as possible. However Touch ID develops on the "iPhone 8" in the next few months for the final shipping version will not deviate from that, perhaps at the expense of not shipping in 2017 at all.
patchythepirate
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Comments

  • Reply 1 of 46
    melgrossmelgross Posts: 31,743member
    I see Apple as having a problem if the new phone doesn't ship. I don't mean if it ships a month, or so late, but not ship at all this year. We'll see a big hit in sales, and the stock price. I don't think either is acceptable to Apple, or to us.

    what we're hearing, and we don't know if it's true, is that the sensor technology does work, but that production of the sensor is behind schedule, so that not enough would be available at launch. If that's true. It would actually be good news. That is, assuming that yield improves enough over some time period.

    i disagree with those who have said that Apple would ship without a touch sensor. That just seems impossible! Too much depends on that sensor, and it's the basis of every mobile initiative Apple has been taking in the past few years. On the back? Well, I sure hope not!

    but remember that Samsung failed, with Synaptic, to get their behind the screen sensor working, so that they had to put it on the back at the last minute, with poor results. If Apple gets it done, it will be a major embarrassment for Samsung and Synaptics.
    edited April 2017 Solimike54fotoformatredgeminipafirelockpscooter63cornchipluisfrochaloquiturrepressthis
  • Reply 2 of 46
    bluefire1bluefire1 Posts: 892member
    A tenth anniversary special edition iPhone 8 to honor the original iPhone arriving in the eleventh year?
    Not happening. Wallet open and ready later this fall.
    edited April 2017 watto_cobra
  • Reply 3 of 46
    I won't buy it if the sensor is on the back!! I hope it's not!
    mike54superklotonTomEcornchipbrian greenrepressthiswatto_cobrajbdragon
  • Reply 4 of 46
    jonyojonyo Posts: 116member
    I hope they can sort it out. Putting the on the back of the phone would be a non-starter for me. The way I use my phone, how I mount it in my car while driving and using it as my music source, the type of case protection I prefer, etc, mean putting the sensor on the back is just not going to work for me. Id that's what they decide to do, I'll just be keeping my iPhone 7 for the time being.
    mike54superklotonredgeminipafirelockpscooter63luisfrochawatto_cobrajbdragon
  • Reply 5 of 46
    mike54mike54 Posts: 339member
    "Cook and company don't ship a product until they feel that what they've developed is the best that they can make it..." Well I hope this is true but I know its not. Cook has given more control to the board and institutional shareholders than compared to Steve Jobs. It will be them deciding if Apple ships a subpar product.
  • Reply 6 of 46
    GeorgeBMacGeorgeBMac Posts: 4,710member
    melgross said:
    I see Apple as having a problem if the new phone doesn't ship. I don't mean if it ships a month, or so late, but not ship at all this year. We'll see a big hit in sales, and the stock price. I don't think either is acceptable to Apple, or to us.

    what we're hearing, and we don't know if it's true, is that the sensor technology does work, but that production of the sensor is behind schedule, so that not enough would be available at launch. If that's true. It would actually be good news. That is, assuming that yield improves enough over some time period.

    i disagree with those who have said that Apple would ship without a touch sensor. That just seems impossible! Too much depends on that sensor, and it's the basis of every mobile initiative Apple has been taking in the past few years. On the back? Well, I sure hope not!

    but remember that Samsung failed, with Synaptic, to get their behind the screen sensor working, so that they had to put it on the back at the last minute, with poor results. If Apple gets it done, it will be a major embarrassment for Samsung and Synaptics.
    The worst thing Apple could do is release a flagship product with a glitch...   That's a nightmare scenario for them.
    But, I'm thinking that most of the sales will go to the 7S anyway -- from people upgrading their 4-5 year old phones.  All they want is one that works and aren't going to care a whole lot about the latest & greatest tech features...   The biggest selling point of the 8 will be a pretty OLED screen -- but the old LCD on the 7S will work just fine also.

    Releasing a product that is not ready is what a marketing based company does.  And that only works for a while - till the customers go elsewhere.



    netmagewatto_cobra
  • Reply 7 of 46
    firelockfirelock Posts: 156member
    If were to have to delay the iPhone 8 in order to perfect its fingerprint technology, I don't think it would be the end of the world for the company, and in fact might benefit them in the long term. Sure, in the short term the company would take a PR and stock price hit, but IF they follow this up by producing an amazing phone with a working front-facing, underscreen fingerprint sensor then they will gain the reputation of the company that doesn't just rush a product to market to meet an arbitrary deadline set by Wall Street. Instead it would cement their reputation of the company that takes the time to get things right and makes an uncompromised product. And this would help validate the reason why Apple charges a premium for its products.
    waverboycornchipluisfrochaMacsplosionnetmagerepressthissteveauwatto_cobra
  • Reply 8 of 46
    The problem is most of you people constantly demand change.  Apple has the nice fingerprint reader in the front but because of all the bitching due to people hating bezels on smartphones, Apple may have to try something else.  I'd rather keep the older TouchID since it's proven technology but whenever Apple uses the same thing for years there's always some demand for change because some other smartphone manufacturer does something else.  Is a minor loss of screen real estate really that big of a deal on a large smartphone?  Just a few years ago almost no smartphones had things like TouchID which is a wonderful security feature.  Sometimes, compromises need to be made.  I'd definitely prefer keeping the chin bezel if Apple can't perfect another type of TouchID.  However, I don't mind if TouchID is on the other side although I understand people complaining who have to mount their smartphones in a vehicle or such.

    I don't know what Apple should do if they can't perfect mounting TouchID under the display.  There's always knee-jerk reactions about how Apple can't do something when the tech-heads expect it to happen.  Too many people are always asking for greater miracles when smartphones are about as cutting-edge as any consumer device on the planet.  A chin-bezel is not the end of the world if Apple can't perfect a below-display fingerprint detection system.  Obviously, Samsung couldn't do it either.  Currently, maybe no company can do it accurately enough.  Technology isn't about, "Your every wish is my command."  New things may take a time to refine.
    edited April 2017 andrewj5790bb-15StrangeDayswaverboyrepressthissteveauwatto_cobra
  • Reply 9 of 46
    maestro64maestro64 Posts: 4,599member
    mike54 said:
    "Cook and company don't ship a product until they feel that what they've developed is the best that they can make it..." Well I hope this is true but I know its not. Cook has given more control to the board and institutional shareholders than compared to Steve Jobs. It will be them deciding if Apple ships a subpar product.
    Where do you come up that Apple broad is making product decisions. The only difference is Steve would challenge the engineers and designers to do what they thought could not be done. I do not believe Cook has this skill, the only question has been who is the driving force. Someone is doing the pushing since we are seeing them pushing the limits and delivering great products that work.
    StrangeDaysrepressthis
  • Reply 10 of 46
    tjwolftjwolf Posts: 278member
    good article - thanks for the explanation.
    pscooter63bb-15repressthiswatto_cobrabadmonk
  • Reply 11 of 46
    tshapitshapi Posts: 292member
    Hasn't it occurred to anyone.  Apple doesn't necisarilly rush products to market. 

    Apple is 5 years out. They still live by the motto the people don't know what they want til yiu hand it to them.  

    The main difference now, is Tim Cook drops teasers and hints about what that may be to keep the world looking forward to it. 

    Apple will release a major update for the iPhone.  If you pay attention to the rumor mill. This update for iPhone 8 started churning since even before iPhone 7 hit. 
    This update everyone is associating with iPhone anniversary probably has nothing to do with that 


    GeorgeBMacwatto_cobra
  • Reply 12 of 46
    In Tim I trust.
    Soliwatto_cobra
  • Reply 13 of 46
    holyoneholyone Posts: 389member
    So what are they going to do about micro scratches on the glass of the display ? if the sensor is behind glass aren't scratches a bigger problem ? Isn't the reason touch ID is behind sapphire to predominantly avoid this very issue ? Has gorilla gotten as good as sapphire ?
    GeorgeBMacrepressthiswatto_cobra
  • Reply 14 of 46
    hmurchisonhmurchison Posts: 12,271member
    tshapi said:
    Hasn't it occurred to anyone.  Apple doesn't necisarilly rush products to market. 

    Apple is 5 years out. They still live by the motto the people don't know what they want til yiu hand it to them.  

    The main difference now, is Tim Cook drops teasers and hints about what that may be to keep the world looking forward to it. 

    Apple will release a major update for the iPhone.  If you pay attention to the rumor mill. This update for iPhone 8 started churning since even before iPhone 7 hit. 
    This update everyone is associating with iPhone anniversary probably has nothing to do with that 



        Apple was wrong.   People didn't want the cylindrical Mac Pro,  and the declining sales of the iPad are a clear indicator that while people see value in the pocketable iOS devices they no longer see value in a larger piece of tappable glass.  I tend to agree with this...for the money a chromebook is a better buy for most people.  

    Putting extraneous work into integrating the touch screen into the front of phone is silly.   Just put it on the back..that makes sense.   In fact where the phones have an Apple Logo on the back is where you should put the touch sensor in the shape of the Apple Logo. 


    avon b7dasanman69
  • Reply 15 of 46
    SoliSoli Posts: 8,975member
    holyone said:
    So what are they going to do about micro scratches on the glass of the display ? if the sensor is behind glass aren't scratches a bigger problem ? Isn't the reason touch ID is behind sapphire to predominantly avoid this very issue ? Has gorilla gotten as good as sapphire ?
    Have display glass scratches been an issue for you on the iPhone? It hasn't been for me.

    Could the display being the Touch ID sensor mean the underlying tech could pick up a much larger sample of your fingerprint compared to the small sensor in an already limited Home Button space? Meaning, any scratches, micro or otherwise, may not be an issue since the area will be large enough that data points with the print won't be adversely affected.

    How do we know that Apple releasing a next gen iPhone wth a comparatively low yield and $1000+ price tag won't come with a sapphire display or that the reason for using sapphire on the home button wasn't unlike Apple shipping LiquidMetal SIM card ejectors: a minor use case to test the material over the material being absolutely necessary for the component to function. I know a paperclip works just fine for the SIM card ejector.
    watto_cobra
  • Reply 16 of 46
    Stop calling it the "iPhone 8" already.
    Geez
    watto_cobra
  • Reply 17 of 46
    SoliSoli Posts: 8,975member
    Stop calling it the "iPhone 8" already.
    Geez
    While it may not be called that, we simply don't know, but we do know what people are talking about when the reference the iPhone 8.
  • Reply 18 of 46
    razormaidrazormaid Posts: 299member
    mike54 said:
    "Cook and company don't ship a product until they feel that what they've developed is the best that they can make it..." Well I hope this is true but I know its not. Cook has given more control to the board and institutional shareholders than compared to Steve Jobs. It will be them deciding if Apple ships a subpar product.
    Agreed!!  Can you say 2016 Touch Bar Laptop? definitely the s was not ready for prime time when it came out and as a beta tester we're STILL dealing with things not resolved.  
    LOL 
  • Reply 19 of 46
    SoliSoli Posts: 8,975member
    razormaid said:
    mike54 said:
    "Cook and company don't ship a product until they feel that what they've developed is the best that they can make it..." Well I hope this is true but I know its not. Cook has given more control to the board and institutional shareholders than compared to Steve Jobs. It will be them deciding if Apple ships a subpar product.
    Agreed!!  Can you say 2016 Touch Bar Laptop? definitely the s was not ready for prime time when it came out and as a beta tester we're STILL dealing with things not resolved.  
    LOL 
    1) How is this different from anything that shipped under Jobs? Nothing is "the best they can make it" because there's always considerations, at the very least, for time and cost. That's today's iPhone is worlds better than the original iPhone, and why the next iPhone will be better than the current one.

    2) What's wrong with the MBP? Everyone I know that has it loves it. Apple reportedly spent nearly a decade working not on the HW and SW for the Touch Bar. It runs it's own version of OS X forked from watchOS on a custom chip that also includes a Secure Element and Secure Enclave for both Touch ID and Apple Pay. It's also seen amazing uptake by 3rd-party SW vendors because did their due diligence with macOS, developer tools and documentation to make it easy to add support for the Touch Bar in apps. I can't recall in the history of Apple Adobe or MS moving so quickly to support a new Apple HW feature that required an entirely new area of coding to support.
    StrangeDaysrepressthiswatto_cobramike1fastasleep
  • Reply 20 of 46
    holyoneholyone Posts: 389member
    Soli said:
    holyone said:
    So what are they going to do about micro scratches on the glass of the display ? if the sensor is behind glass aren't scratches a bigger problem ? Isn't the reason touch ID is behind sapphire to predominantly avoid this very issue ? Has gorilla gotten as good as sapphire ?
    Have display glass scratches been an issue for you on the iPhone? It hasn't been for me.

    Could the display being the Touch ID sensor mean the underlying tech could pick up a much larger sample of your fingerprint compared to the small sensor in an already limited Home Button space? Meaning, any scratches, micro or otherwise, may not be an issue since the area will be large enough that data points with the print won't be adversely affected.

    How do we know that Apple releasing a next gen iPhone wth a comparatively low yield and $1000+ price tag won't come with a sapphire display or that the reason for using sapphire on the home button wasn't unlike Apple shipping LiquidMetal SIM card ejectors: a minor use case to test the material over the material being absolutely necessary for the component to function. I know a paperclip works just fine for the SIM card ejector.
    Scratches on glass that only need to display images is no issue but scratches on glass that also need to take images could be a big one, but as you say if the entire screen can take the image then maybe no problem but I'm not sure if that's what Apple is going to do considering cost of placing a screen full sensor most of which will never be used for that purpose , that would be only way to realize the argument you're making, coz unless the sensor is full screen no matter how much bigger a print a finger makes area wise the ppi on the sensor means that even a tiny mark would seem big thus possibly affecting the hole thing don't you think?, but I  was just wondering though maybe it'll be as you say we'll see this fall


    what I was thinking Apple might do however is place the sensor at the bottom of the display like a bar wherein that entire chin area can detect a finger also allowing great left and right hand access and minimize costs of placing a costly sensor everywhere even in areas that would likely never be used for print scanning, I however have not seen or read anything alluding to something like that though
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