Touch ID on the Rumored “All-Display” iPhone 8: Switched Places, Hiding in Plain Sight?

Ming-Chi Kuo, who has a track record, though not a perfect one, on iPhone rumors, seems pretty insistent that there isn’t Touch ID on the iPhone 8. Yes, Apple’s well-known, well-regarded authenticate-to-login-and-buy button, which is no longer an actual button as of iPhone 7, is predicted to disappear, and its functionality with it, to be replaced by…some 3-D sensing thing, apparently. Why? In a nutshell, the following reasons:

  • iPhone 8 will be “all screen”
  • Apple isn’t able to have its current-paradigm Touch ID hardware “scan through” from behind the rumored OLED display, at least not at an acceptable level.

There’s just one thing. Who said Touch ID has to be on the display?

“Oh, you mean a Touch ID button on the back, kinda like all those other Android models? Well, you know what we think of that?”

I know. And in my heart of hearts, I don’t TOTALLY disagree with this amusing assessment from Boy Genius Report, which commented on the possibility of Touch ID being somewhere you couldn’t see while looking at the display:

Hey, if iPhone 8 sucks, we’ll hate it. 🙄

For whatever reason, everyone (or most everyone) seems to be forgetting one other area Touch ID could be without compromising a button-free, mostly-screened front side. I already kind of gave it away: The side. Most logically, what we currently know as the combination power button/sleep-wake switch:

“Isn’t the Touch ID sensor, whether Mac or iPhone, way bigger than the power switch?”

Yes and…perhaps not as much as you might think.

Doing a quick pixel ratio / schematics analysis of the current smallest Apple Touch ID sensor in existence — that is, the one on the Touch Bar MacBook Pro series — it is indeed the case that the cover glass looks to be more or less 10mm in height and width. When you consider that iPhone 7 is 7.1mm in thickness, that would seem to present a problem.

On the other hand:

What do I mean by “secret”? Well, if you look at the active sensor — of course, a few leaps of faith are involved without disassembling a MacBook or iPhone 7 on one’s own — it doesn’t look to be the same size as the cover glass atop it. Instead, the sensor (the gold/copper element at center) looks to be less than a third of the width of the metallic-looking plate backing it.

To be clear, this isn’t a prediction I have anything to back other than a pure guess. And sure, when you’re working with 7 or so millimeters of space, shrinking a third-generation Touch ID button/sensor to adapt to that space seems…kind of improbable.

At least miniaturizing a sapphire-lensed sensor sounds less impossible, for the moment, than hiding Touch ID behind an array of OLED pixels. Turns out, Apple’s been mulling this over for a while. At least a couple of years, to be more specific.

And to end the post, before you object too strongly about the usability, pretend to “login” to your iPhone (if you’re right-handed) via the power/sleep-wake switch with your thumb (by the way, THE digit you use for Touch ID in a one-handed context), or by gently supporting your iPhone with, say your left hand while using your other four non-thumb digits on your right. Or, if you’re a lefty by nature, “login” with your left index or left middle finger on your iPhone 6/7 (360-degree readability, after all).

It may feel less natural, sure, but I bet you think it beats aiming or feeling around for a touch target on the opposite side of a display. As long as you can cover the button, Apple’s fingerprint detection should be able to do the rest. And if Apple can truly pull off a nearly-all-display front as is being rumored, I suspect it’s a tradeoff the vast majority of iPhone 8 owners will happily live with.

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