Today the US Patent & Trademark Office published a patent application from Apple that relates to an iPhone using indoor location tracking in order to find a second iPhone in an indoor facility. For example, two friends wanting to know where the other is in a mall or a mother tracking her child. Apple describes using infrared technology for indoor tracking which they claim is superior to  using GPS.

Apple notes in their patent filing that electronic devices may include one or more components that may be used to share the location of the electronic device with an additional electronic device. Consider an example where a first person has a cellular telephone. The first person may wish to find a second person (who also has a cellular telephone) in a crowded indoor setting. Technology within the cellular telephones of the first person and the second person may be used to help the first person more easily find the second person.

Location sharing may be improved over the use of GPS for indoor use by providing infrared beacon functionality in the cellular telephones of the first person and the second person.

Apple notes that when the second person shares their location with the first person, the second person's cellular telephone may emit infrared light. The infrared light is not visible to the first or second person and therefore is not disruptive to any people in the area. The first person may hold their cellular telephone to face the general direction of the second person. An infrared image sensor in the first person's cellular telephone is used to detect the infrared light emitted from the second person's cellular telephone (and, correspondingly, the second person's location). The first person's cellular telephone then displays an image (or provides other output) that identifies the location of the second person. The displayed image may highlight the second person's location through an increased brightness (e.g., spotlight) at the second person's location, a visual indicator (e.g., an arrow or circle) at the second person's location, etc.

Apple's patent FIG. 1 below is a schematic diagram of an illustrative electronic device, an iPhone, that includes infrared point sensor used for indoor location tracking;  FIG. 4 is a diagram of an illustrative infrared beacon system where a first electronic device locates a second electronic device that emits an infrared beacon.

Apple's patent FIG. 5 above presents a flowchart of illustrative method steps for operating an electronic device that locates an infrared beacon in an additional electronic device; FIG. 7 is a state diagram showing illustrative operating modes for the flood illuminator in an iPhone.

As shown in FIG. 7, the flood illuminator is operable in both face recognition (#122) and infrared beacon mode (#124). In both modes, the flood illuminator may be turned on to emit infrared light. The brightness of the flood illuminator may be greater in beacon mode to help the device be detected by an additional electronic device.

For more details, review Apple's patent application number 20230221435.

Patently Apple has covered many of Apple's indoor tracking patents since at least 2015 that you could review  here: 01, 02, 03, 04, 05, 06, 07 and more.