Canon Patent Application: Sensor Thermal Expansion

This is a curious patent (Japan Patent Application 2024-002151). When I was quickly culling through the applications my first thought was that it was a curved sensor, but reading more it became a far more curious application.

This patent application deals with very small changes that can occur when the camera is heated up or cooled down. As you may know, metal tends to shrink and expand depending on temperature. This is called thermal expansion; the rate of expansion is different depending on the metal.

What Canon wants to do is to curve the plate on which the sensor rests to minimize the effect of thermal expansion.

This usually isn't a problem for longer focal length lenses, but the smaller the focal length and the faster the aperture, the more critical the sensor position becomes.

The present invention provides an imaging method that makes it possible to suppress changes in the distance between the final lens surface and the image sensor due to temperature changes without increasing costs or increasing the size of the member that holds the image sensor. 

I can't see too many practical applications unless you are shooting video with your lens wide open on manual focus. Then as the sensor gets hotter, the focus could conceivably shift.

I think this is pretty esoteric. It could have been more of an issue with DSLRs than mirrorless as because the autofocus would happen on another sensor, it would be more prone to smaller shifts in the position of the image sensor. On Mirrorless cameras, I don't think this is much of a problem – but Canon certainly thought it was worthy of a patent application.

As with all patent applications, this may never end up in an actual camera product. It does speak well for Canon that they look at any and every way possible to make sure we have the best possible experience with their camera systems.

Japan Patent Application 2024-002151

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