In 2011, Patently Apple posted an IP report titled "Whoa - Apple Wins a 3D Display & Imaging System Patent Stunner." The patent described an advanced 3D Display and Imaging System. Apple's patent covered a wild 3D system that could generate an invisible space in front of the user that could allow them to work with holographic images or project their hands onto a screen in front of them to manipulate switches or move pieces of virtual paper or parts of a presentation. One could only image how this could be applied to 3D gaming, business or medical applications in the future. A key patent figure from that patent is presented below. 

Today the US Patent & Trademark Office published a patent application from Apple that relates to their invention of the past with more specificity and range of devices it could apply to. 

Electronic Devices with Air Input Sensors & Zones 

In Apple's background they note that electronic devices such as laptop computers and other electronic devices include input devices such as keyboards, touch pads, and touch sensitive displays. Using these input devices, users can control the operation of the electronic devices. It can be challenging to operate electronic devices using certain input devices.

For example, some input devices are only configured to detect touch input on a two-dimensional surface. This may overly limit the types of input that a user can provide to an electronic device.

To enhance the ability of a user to operate an electronic device, Apple's invention covers electronic devices that provide air input sensors. The air input sensors may detect the presence of external objects such as a user's fingers, a stylus, or other object, without direct contact between the objects and the air input sensors.

For example, air gestures with the user's hands and/or movements of a stylus or pen in the air above and/or adjacent to the electronic device may be used to control the electronic device.

The air input sensors may include ultrasonic transducers that emit ultrasonic signals towards the volume of air and that detect the ultrasonic signals after the signals reflect from the external object. Using time-of-flight measurement techniques, control circuitry may track the movement of the external object in the volume of air near the electronic device.

A display may display visual feedback of the air input, such as shadows that preview where the input will be directed to on the display. The volume of air where input is detected may be divided into multiple input zones that trigger different actions from the electronic device. The ultrasonic transducers may include acoustic lenses to focus sound onto the transducers and/or to diverge a sound signal across a given range of angles.

Apple's patent FIG. 2 below is a perspective view of an illustrative electronic device such as a cellular telephone, tablet computer, or other electronic device with air input sensors.

Further, device 10 in FIG. 2 may include one or more air input sensors #20 supported by the device housing (#22). Air input sensors may serve as position monitoring sensors that track the position of external objects such as external objects that may be part of a user's body (e.g., hand, finger, etc.), or could be an Apple Pencil or other input device such as a regular ink-pen or paintbrush.

Apple's patent FIG. 3 above is a perspective view of an illustrative electronic device such as an iPhone or iPad with air input sensors; FIG. 4 is a perspective view of a MacBook with air input sensors and a display that provides visual feedback in response to air input from a user's hands.

Apple's patent FIG. 5 below is a perspective view of an illustrative electronic device with air input sensors and a display that provides visual feedback in response to air input from a stylus; FIG. 7 is a perspective view of an illustrative electronic device with ultrasonic air input sensors for detecting air input; 

Apple's patent FIG. 6 above is a side view of an illustrative electronic device with air input sensors configured to detect air input in different input zones above the electronic device; FIG. 8 is a side view of an illustrative electronic device having ultrasonic air input sensors that may be used to determine the angle of arrival of incoming acoustic waves.

Apple's patent application US 20230081556 A1 is a very detailed patent that you could review in its entirety here. Apple Research Scientist, Bogdan Bucheru, is noted as the lead inventor.