Apple is considering a strobe accessory for iPhone photography as evidenced by a newly granted patent (US 11743981 B2) for an “accessory strobe interface.”
About the patent
Small, mobile multipurpose devices such as smartphones and tablet or pad devices commonly have one or more cameras for taking pictures. An internal strobe or flash positioned near the camera is typically provided on such multipurpose devices as well.
These devices may also include programming that determines whether the strobe is to be used in taking a picture (e.g., based on ambient light conditions) and/or the duration and intensity of strobe illumination while the picture is taken. A metering phase (or state) on the device is typically used to determine whether the strobe is to be used and, if used, the duration and intensity of the illumination.
Internal strobes may be provided on mobile multipurpose devices to provide convenience for the user and to maintain a small form factor for the device. Apple says that external strobe devices (e.g., external strobe accessories) have generally not been developed for mobile multipurpose devices as cameras on mobile multipurpose devices are most frequently used for photography where there is little need or desire for additional illumination (e.g., amateur photography purposes).
However, as camera technology in mobile multipurpose devices advances, there is increasing potential that mobile multipurpose device cameras may be used for more professional-type photography. There are, however, challenges in providing external strobe accessories for mobile multipurpose devices that utilize existing connectors on the mobile multipurpose devices to provide low-latency timing synchronization between the internal strobe and the external strobe accessory.
Apple’s idea is for an accessory strobe device capable of mirroring the output of an internal (built-in) strobe of an iPhone (or iPad). The mobile device may output a strobe control signal that includes information for both a metering strobe state (e.g., metering phase) and a main strobe state (e.g., main (normal) flash phase) of the internal strobe.
Summary of the patent
Here’s Apple’s abstract of the patent: “An accessory strobe device for a mobile device may operate to provide illumination at the same time as an internal built-in strobe (flash) of the mobile device. The accessory strobe device may receive a single, unidirectional signal from the mobile device that provides signals related to the timing of the internal strobe.
“The accessory strobe device may process the received signal to control its illumination using the timing and relative intensity levels of the internal strobe during metering and main (normal) flash operations associated with a camera on the mobile device. With the accessory strobe device operating using timing and relative intensity levels in a predetermined relationship with the timing and relative intensity levels of the internal strobe, the accessory strobe device may be used to complement the internal strobe during the metering and main (normal) flash operations for the camera.”