In September 2024 Patently Apple posted an IP report that was related to Apple working on Optical Touch Sensors for future iPhones, iPads Apple Watch and more that are insensitive to the presence of Moisture/Water Droplets. Today, a second patent on this very subject has surfaced with new information and patent figures.   

Optical touch sensing can be employed in the touch sensor panel to detect the presence of a finger or other object in contact with a detection surface. However, when optical sensing is employed, light impinging on the boundary between the detection surface and a medium (e.g., air, water, or other liquid or moisture) above the detection surface can reflect off the boundary, or refract as it passes through the boundary, and cause false or inaccurate touch detection. It can therefore be challenging to utilize optical sensing for touch detection in the presence of moisture.

PHOTO-SENSING ENABLED DISPLAY FOR TOUCH DETECTION WITH CUSTOMIZED PHOTODIODE AND LIGHT EMITTING DIODE COMPONENT LEVEL ANGULAR RESPONSE

An electronic device may have a touch sensitive display that is insensitive to the presence of moisture. The display may have a two-dimensional optical touch sensor such as a direct illumination optical touch sensor or a total internal reflection touch sensor. The optical touch sensor may be used to gather touch input not only in benign conditions (e.g., in the absence of water or other moisture), but also while the electronic device is immersed in water or otherwise exposed to moisture.

An array of pixels in the display may be used to display images. A display cover layer may overlap the array of pixels. One or more light sources may be included to illuminate an external object such as a finger of a user or a stylus when the object contacts a surface of the display cover layer. This creates scattered light that may be detected by an array of light sensors. The light sources and the light sensors may be mounted on a common substrate with the array of image pixels (which may be formed by crystalline semiconductor light-emitting diode dies).

In some embodiments, the light sensors (light detectors) and light sources can include photodiodes and light emitting diodes (LEDs) (e.g., standard LEDs, organic LEDs (OLEDs), micro-LEDs and the like). The LEDs and photodiodes can be configured in a direct illumination optical reflective touch mode to detect the presence of an object such as a finger or stylus by detecting modulated light generated by some of the LEDs and reflected off the object.

In some examples, interference filters may be included over the light sources and/or the light detectors to improve discrimination between a user's finger and water droplets.

An interface between air and the display cover layer is characterized by a first critical angle. An interface between water and the display cover layer is characterized by a second critical angle. The interference filters over the light sources may have a greater transmission for light at the wavelength of interest (such as near-infrared light) at a first incident angle that is less than the first critical angle than at a second incident angle that is greater than the first critical angle.

The interference filters over the light detectors may have a greater transmission for light at the wavelength of interest (such as near-infrared light) at a first incident angle that is greater than the second critical angle than at a second incident angle that is less than the second critical angle.

Direct illumination optical touch sensors and total internal reflection touch sensors both rely on light passing through the detection surface of a cover material located above the integrated touch screen to photodiodes located below the cover material.

However, light impinging on the boundary between the detection surface and a medium above the detection surface (e.g., air, water, finger, or stylus), from either above or below the detection surface, can reflect off the boundary or be refracted as it passes through the boundary. In some instances, this reflected or refracted light can be detected and incorrectly identified as a touching object.

Accordingly, in some embodiments of this patent, light illuminator angular filters can be employed within each LED component configured as an illuminator to limit the illumination angle of those illuminators, and light detector angular filters can be employed within each photodiode component configured as a detector to limit the detection angle of those detectors.

Each angular filter acts as a mask, including an inner mask baffle and an outer mask, that together effectively block or filter light transmitted, reflected or refracted within the cover material to facilitate a customized angular response that reduces or eliminates the false detection of water droplets on the touch surface.

For full details, review Apple's patent application 20250068285. The patent credits the seven Apple inventors below;

• Moe Yeke Yazdandoost: Lead Tech Sensing Systems Architect
• Yang Deng: Sr. Optical Engineer
• Paul Gelsinger: Optical Engineer
• Jason Griesbach: Sr Hardware Engineer
• Brian King: Senior Technologist
• Majid Gharghi: Product and Technology Development
• Ileana Rau: Hardware Engineering