Imagine an AirPods wireless charging case that was big enough to hold an iPad. That’s what is at the heart of the newly-granted patent, “Wireless Charging System With Simultaneous Wireless Power Transfer At Different Frequencies.”

There is more to it than that, to the extent that the patent also refers to a “charging mat” some 23 times in its 13,000-word description. That could be enough to suggest this patent is left over from Apple’s failed AirPower, but it then says “case” some 45 times.

“An electronic device in a wireless power system may be operable with a removable accessory such as a case,” says Apple. “The case may have a folio shape with a front cover portion that covers the display of the electronic device.”

Whatever the configuration of the wireless charger, the patent is concerned with devices that have “coplanar power transmitting and power receiving coils.” That is, they can transmit and receive wireless power, and do so using different frequencies “to mitigate crosstalk.”

It doesn’t immediately seem sensible to have a device that will charge other devices wirelessly, while it is itself being wirelessly charged from a third device. It would sound more efficient to skip this charger, and just place something like an iPad or an iPhone onto that third device.

However, this is how the wireless charging case of an AirPods or AirPods Pro works. You never charge the earbuds directly, you put them inside the case, and then place the case on a wireless charging mat.

Much of the patent is concerned with wireless power transmission and receiving regardless of the form factor, but the main example presented is that of a case — in some form.

“[For example, a cover may have] a folio shape (sometimes referred to as a folio cover) with a rear portion and front portion,” says Apple. “Rear portion may have a rectangular recess with a rear wall surrounded by peripheral sidewalls and/or other suitable coupling structures (straps, clips, a sleeve, corner pockets, etc.) that allow cover 102 to receive and couple to the additional device.”

Apple does specify that the device being charged is “a portable electronic device such as a wrist watch, a cellular telephone, a laptop computer, a tablet computer, an accessory such as an earbud, or other electronic equipment.”

It does not mention MagSafe at all. However, it does allude to it.

“Additionally,” continues the patent, “the removable accessory may include a magnetic alignment structure that magnetically couples to additional magnetic alignment structures in the electronic device and/or the wireless power transmitting device to align coils within the charging system during operation.”

This patent is credited to three inventors, including Zaki Moussaoui. His previous work centers on power, and includes a patent concerning how to prevent CarKey interfering with wireless charging.