Is the lens of ultrasonic motor patented by Canon?

The so-called ultrasonic lens is actually a lens driven by an ultrasonic motor. The ultrasonic motor was first used on the lens by Canon in 1987, but its capability is still relatively thin. So as long as it is a miniature ultrasonic motor, after a while, many ring ultrasonic motors are used now, and Canon registered this skill as a patent, so that in 2002, just after 15, other factories began to launch ultrasonic motor-driven lenses on a large scale, and patent maintenance work has been done.

However, there are different names for ultrasonic motor drive. Canon is called USM, Nikon is called SWM, but the label on the lens is AF-S, Sigma is called HSM, Pentax is called SDM, Sony and Minolta are called SSM together, and Olympus is called SWD. Longteng and Tuli have not yet introduced the lens driven by ultrasonic motor.

The annular ultrasonic motor drive was originally a patent of Canon, but it passed the patent maintenance period. Now Nikon, Sigma and the original Minolta all have similar products.