Apple's new iPhone 11 models introduced a matte glass back panel. A new Apple patent application published by the U.S. Patent Office yesterday suggests that their matte finish could take a twist in the future forming a different kind of glass back that's a mixture of both smooth and matte. The matte finish could be associated with backside touch controls for a future iPhone, iPad or part of the frame of smartglasses.  

Apple calls these matte patches associated with a touch-sensitive enclosure "tactile friction features." These features may also extend to the enclosure's sidewalls.

In the opening line of Apple's invention summary they state: "Aspects described herein relate to tactile features formed along an exterior surface of an electronic device housing."

More specifically, Apple describes the new tactile friction features invention this way:

"In embodiments, a glass surface (e.g., a base surface) of the housing has protrusions or depressions ("tactile features") that provide a different coefficient of friction with a touching object than a smooth glass surface does, and so provides a different feel than does a glass surface lacking such tactile features.

Tactile features that change a coefficient of friction for a finger or other object in contact with the tactile feature, as compared to a glass surface that is substantially smooth or otherwise lacks such features, are called "tactile friction features" in this document. Further, it should be understood that references to "friction" in this document are to kinetic friction, unless otherwise stated."

Later Apple notes that the movement of the finger may correspond to a touch input on a touch-sensitive surface of a device. The touch input may include gesture input that involves movement of the finger while applying light pressure to the glass surface.

Touch input may also correspond to taps, momentary touches, twisting finger input, and other types of touch input that can be performed using a finger.

The tactile friction features could be on a flat surface or be associated with areas with a slight concave surface.

While the following examples are provided with respect to finger-touch input, similar principles may be applied for Apple Pencil input or input using another type of object.

Like with most Apple patents, they note that their invention relating to tactile friction features can be applied to an iPhone, iPad, MacBook, iMac or future wearable devices. It could also apply to input devices, appliances, or virtually any other type of electronic product or device component.

Apple's patent is a technical one and provides no examples of what the backside touch-sensitive areas would actually control. Patently Apple posted a report just prior to the iPad being released back in 2010 titled "Apple: The Tablet Prophecies."

It was in this report that we pointed to a previously published Apple patent illustrating backside controls on a future tablet. It was a bit of a mystery as to how a user would be able to identify the back controls for games or other applications at the time. Now with Apple's tactile friction features in yesterday's patent application, we can now see how Apple could apply this in the future.

Apple's patent FIG. 1A below shows a finger touching and moving across a smooth glass surface; FIG. 16 is a block diagram of a sample electronic device that can incorporate a glass structure having tactile friction features. In respect to block 1606 highlighted in yellow, Apple states: "As one example, a button assembly 1606 may include a cap or other surface formed from glass, ceramic, plastic, or any other suitable material. That cap or surface may have tactile friction features.

Apple's patent FIG. 10A above is a first cross-section view of a finger contacting tapered tactile friction features formed on a glass surface; FIG. 12 shows a cross-section of a glass structure having tactile friction features with a peaked upper surface;  FIG. 14 shows a cross-section of an example glass structure having tactile friction features with a concave surface.

Lastly, Apple threw in a real oddball patent figure as shown below in FIG. 2. The patent overall is about the "housing" of an Apple device having tactile friction features. So where does this feature fit on a display? Apple never answers that question being that it's a technical patent with zero marketing value.

Considering that there isn't a straight forward answer provided by Apple, we're left throwing in an educated guess. On a clear surface like the cover glass on a display, the tactile friction features would almost act as an invisible control or button, be it oblong or circular in shape.

It wouldn't be seen by the user because of its microscopic size but the user would be quick to understand that there's an invisible bottom in the right corner, for example, that's a friction control to shut an iPhone or iPad off which would eliminate a physical button. A friction area at the top left corner could control audio if the friction area would be oblong.

Apple has really gone out of their way to hide the direct intent of their tactile friction features, but once you get your head around the idea, it's an interesting but different twist to what competitors like Huawei are doing in some applications. In the video below, Huawei uses an invisible-like touch control to eliminate up and down volume controls. This is what Apple's invention could deliver.

Apple's patent application 20190331940 that was published yesterday by the U.S. Patent Office was filed back in Q1 2019, with previous work being done in April 2018. Considering that this is a patent application, the timing of such a product to market is unknown at this time.