Patently Apple reported yesterday on a recently granted patent for invisible backside buttons and slider controls. The patent’s (8,436,816) abstract:
An input device includes a deflection based capacitive sensing input. Deflection of a metal frame of the input device causes a change in capacitance that is used to control a function of an electrical device. The input appears selectively visible because it is made of the same material as the housing it is contained in and because it is selectively backlit through tiny holes.
Apple has been using indicator lights shining through small micro-perforations in several devices, including their Bluetooth keyboard. The result is a very elegant design unmarred by apparent through-holes for LEDs. This patent represents a way to also allow for user input through touch controls that are selectively illuminated.
The buttons are certainly inaccessible to everyone when they are in their invisible state—that is the point—that the buttons will disappear into the case of the device when they are not needed.
When active or lit up however, the buttons remain “invisible” or imperceptible to those who cannot see or who find themselves in circumstances where they cannot look at the device (say while driving). This would make a non-personal device with such technology inaccessible to these users. On a personal device, the buttons may still be usable if the user can find them using other landmarks, such as the distance from a corner, edge or other feature of the device.
As another example of tactilely imperceptible controls, I have a laptop with a capacitive, light-up touch area with non-tactile media and volume controls. When they aren’t lit up, I cannot very easily find the control I want. I often end up touching several of them trying to find the mute button for example. Having some texture would make it much easier to find the control I need.