>> Seems to me this all makes it similar in functionality to a traditional >> step(per) motor. Technically it is even more closely related to a >> piezoelectric motor, although I don't believe it's exactly the same thing. >> >> Both of which can come in packages that are identical to a traditional >> DC motor, and could as far as I can tell be used in an in-body motor AF >> system - which would cancel out the need for the traditional feedback loop. >> > > A magnetic stepper motor could potentially be built in a ring format. > Pentax has displayed a very practical solution in opting to use > traditional fixed magnet linear motors in its SR implementation. > Minolta on the other hand developed a new type of linear motor which > whilst ingenious probably tied up significant of engineering resources > as would have the development of the Canon USM system. Who knows, > Pentax could pull another practical rabbit out of a hat and surprise > us? > > Feedback loop would still be required though, much like the Canon > system which apparently uses an optical strip. > Hmmm. Maybe you'd need some kind of way of knowing where the final moving parts are, but surely a stepper setup does not require feedback of the kind that tells you how much the screw has rotated (if you use it in such a setup) - since you can tell the motor how much to rotate it instead, and expect it to do the job very accurately.
- Toralf -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
