Yesterday, the US Patent & Trademark Office published a patent application from Apple that focused on an iPad that could detect a protective cover placed over its display and take actions to compensate for the changes to the usage of the iPad. According to Apple, screen protectors can alter the light of the display screen and thereby impact the performance and sensitivity of the touch screen. Apple's solution is detailed.

In Apple's patent background they acknowledge that some users prefer to apply a screen protector to the cover glass to improve the durability, appearance, and functional characteristics of the cover glass. Screen protectors generally are made to cause minimal distortion to the images shown by the underlying display screen, but they can alter the light of the display screen in minor but perceptible ways.

Apple further notes in their patent application that screen savers can interfere with the operation of the touch screens they are used to protect. For example, the materials and thickness of a screen protector can cause distortion or attenuation of the electric field emitted by a user instrument (e.g., a stylus tool or finger) and sensed by the electrical traces of the touch screen. This can negatively impact the performance of the touch screen by reducing its sensitivity, touch detection accuracy, and speed. 

Apple's invention relates to systems, apparatuses, and methods for detecting and compensating for the application of a screen protector to a touch screen device.

A computing device having the touch screen device can include a processing device in communication with sensors used, in conjunction with the processing device, to detect the presence of and, potentially, the physical characteristics of (such as the color or thickness of), a screen protector applied to the cover glass of the touch screen.

Upon detecting the screen protector, the processor can alter input settings interpreting the signals of the touch screen to compensate for or reduce the negative impacts of the addition of the screen protector to the device.

In some embodiments, the computing device can be configured to receive a first signal from the touch input device over time and can detect a first signal pattern in the first signal.

The device can also receive a second signal from the touch input device over a second time and can detect a second signal pattern in the second signal. The device can then determine a difference between the first and second signal patterns and adjust a touch input setting of the device (e.g., its touch screen) to limit the effects of a screen protector causing the difference between the first and second signal patterns.

The differences in patterns can include, for example, a change in the average magnitude of the capacitive touch input over time or a change in the shape of a moving input detected by the touch screen. In this way, the output of the touch screen can be monitored over time and then used to determine that a user has applied a screen protector to the display and to react to that change in state of the device, such as by implementing a different capacitive input detection processing algorithm, adjusting the color balance of the output of the display, or curve-fitting, filtering, interpolating, or otherwise smoothing the input.

Apple's patent FIG. 1B shows a schematic view of an iPad with a cover layer or screen protector installed. As shown, a sensor distribution #130 can have a different maximum magnitude #132, standard deviation, and other shape characteristics when the same input is provided (as compared to distribution with a screen protector). This change in distribution can introduce uncertainty into the system regarding the location of the input.

Apple's patent FIG. 2 above is a chart illustrating a method for detecting a cover layer and adjusting the way that touch input is interpreted and used by the computing device – in this case an iPad.

Apple's patent FIG. 6B above shows a computing device having multiple capacitive touch input devices and a controller in the iPad's housing.

Apple's patent FIG. 9 shows a chart illustrating a process for detecting a cover layer and adjusting the way touch input is interpreted and used by the computing device – in this case an iPad.

To review its full details, review patent application 20230280868. While the  focus of the patent is on an iPad with touch and Apple Pencil input, the patent does note that the invention could apply to an iPhone and a MacBook with a touch display, should that ever surface.