Canon patent application shows shutter-like barrier mechanism for protecting mirrorless image sensors

Left: The barrier mechanism when it’s closed; Right: The barrier mechanism when it’s open.

Canon has filed a new patent application for an in-camera mechanism designed to protect the shutter and image sensor of its mirrorless cameras from dust and debris when no lens is attached.

Japanese patent application number 2019–234718 describes (machine-translated) an ‘invention related to interchangeable lens imaging equipment with a barrier mechanism to protect the imaging element.’

What’s interesting about the mechanism described in the patent text is that it’s entirely passive. Instead of being powered by a motor, the mechanism automatically opens when a lens is twisted into the lens mount and closes as the lens is removed from the lens mount, thanks to an array of integrated levers and springs.

As a lens (or body cap) is screwed onto the camera’s bayonet mount, the barrier mechanism opens up to create a clear path to the image sensor.

In theory, such a design should help to keep costs down and reduce potential points of failure, as it won’t require an additional motor or power of any kind. The patent suggests this mechanism would sit behind the frame of the lens mount, between the electrical contacts and where the image sensor is positioned.

The patent doesn’t mention what kind of material the barriers would be made out of, but the illustrations do appear to suggest the barrier elements are more robust than what you would see with a standard shutter.

An exploded view of the components used to create the barrier mechanism.

As always with patents, there’s no knowing whether or not this will ever come to fruition, but it makes sense as Canon and others continue to expand their respective mirrorless camera lineups. Compared to DSLR cameras, mirrorless cameras expose the image sensor more and while some have a feature that closes the shutter to protect the image sensor when a lens is removed, this passive method wouldn’t rely on batteries, motors and software to keep the image sensor safe.

Furthermore, if fully electronic shutters become more commonplace on larger image sensors, this could very well be a solution to keeping the image sensor safe if there’s no physical shutter inside the camera.