Technical Glossary

  Ultrasonic Silent Drive 

USD is a Tamron proprietary technology and offers a new dimension in focusing precision and speed. Tamron’s USD works with high-frequency ultrasonic vibrations which are produced by a ring called a ‘stator’. Energy from the vibrations is used to rotate an attached metallic ring known as a ‘rotor’. Piezoelectric ceramic, an element that produces ultrasonic vibrations when a specific voltage frequency is applied is arranged in a ring formation on the stator. This electrode configuration of piezoelectric ceramic causes two ultrasonic vibrations to occur in the stator.

By effectively combining these two ultrasonic vibrations, it is possible to convert the energy from the vibrations that produced simple motion into energy known as ‘deflective traveling waves’, which then moves around the circumference (rotation direction) of the ring.

With the USD, the friction between these deflective traveling waves created on the metallic surface of the stator and the surface of the rotor produce force, causing the rotor to rotate. The focusing ring of the lens, which is linked to the rotor, is thus moved, creating a fast and smooth auto-focus drive.

Because the technology is built on a rotor, it offers full-time manual focus control without having to fumble with a switch.

And because speed is nothing without stability, the USD technology is combined with Tamron´s own ( VC) Vibration Compensation image stabilizer.