Electromagnetic drive device for shutter

摘要

An electromagnetic drive device for a focal plane shutter having a tubular yoke and a cylindrical permanent magnet concentrically fixed to the yoke by clamping apparatus. A moving coil in a space between the permanent magnet cylinder and the yoke rotates about the axis of the permanent magnet and is drivingly connected through a shaft to blades of a leading or trailing curtain of the shutter, wherein a pair of holes are formed in one of the end surfaces of the permanent magnet cylinder symmetrical with respect to the axis thereof. The running characteristic of the shutter blades can be adjusted when the distribution of magnetic flux density is previously adjusted by turning the permanent magnet with the use of a tool engaged in the holes.