There have been a few articles written about the Apple Watch overheating, like this one from iKream posted earlier this month. Yesterday, the US Patent & Trademark Office published a patent application from Apple that relates to systems and methods for precisely determining a temperature gradient between two or more discrete locations within a portable electronic device housing like Apple Watch. It's a possible solution which could greatly improve keeping the temperature of future Apple Devices cooler.

In Apple's patent background they note that an electronic device such as Apple Watch can include a temperature sensor. An output from the temperature sensor can be used to calibrate, or adjust, an output from another sensor or subsystem of the electronic device that is sensitive to changes in temperature.

Many electronic devices include multiple sensors or subsystems that are sensitive to temperature. However, because conventional temperature sensors reserve volume within an electronic device housing, and can be expensive components, it is often impractical to include a temperature sensor dedicated to each temperature-dependent sensor or subsystem of an electronic device. As a result, at least some sensors or subsystems of conventional electronic devices are operated in a suboptimal, temperature-dependent, manner.

Overall, Apple's patent covers an electronic device (e.g., Apple Watch, Apple Pencil, AirPods Pro & Max, a future smart cuff and/or health monitoring devices & more) housing that encloses a temperature sensing system including a temperature sensor and a differential temperature probe.

The differential temperature probe includes a flexible substrate defining two ends. A first end is thermally coupled to the temperature sensor and a second end is thermally coupled to a surface, volume, or component of the electronic device.

The temperature probe is an in-plane thermopile including a series-coupled set of thermocouples extending from the first end to the second end. A temperature measured at the temperature sensor can be a first measured temperature and a voltage difference across leads of the differential temperature probe can be correlated to a differential temperature relative to the first measured temperature. A sum of the differential temperature and the first measured temperature is a second measured temperature, quantifying a temperature of the second end of the differential temperature probe.

An internal probe location may be defined relative to a particular electronic component within an electronic device housing, such as a processor, memory, battery, display, or input sensor. In other cases, an external probe location may be defined relative to an external surface of an electronic device housing, such as a cover glass surface, an exterior button or input device, or a back surface such as a back crystal of a smart watch.

Apple's patent FIG. 1 below depicts an example Apple Watch that can incorporate a temperature sensing system; FIG. 2 depicts a simplified system diagram of a temperature sensing system disposed within the housing of an Apple Watch; FIGS. 5C – 5F depict an example differential temperature probe that takes a low aspect ratio rectilinear shape. In particular, the temperature probe 500a implemented as an in-plane thermopile can be supported by a substrate (#502) onto which a continuous conductive path (#504).

As shown in FIGS. 5E-5F above, a cross-shaped temperature probe may be suitable in some implementations. In particular, in FIG. 5E, a temperature probe #500c is depicted.

For engineers wanting to dive deeper into the details, review Apple's patent application number 20220026284.

Considering that this is a patent application, the timing of such a product to market is unknown at this time.