Magnetic particle carrying device, and developing unit, process cartridge, and image forming apparatus using the same, and surface treatment method of the same

摘要

A magnetic particle carrying device includes a magnetic field generator and a hollow cylindrical structure. The magnetic field generator generates a magnetic field. The hollow cylindrical structure encases the magnetic field generator and attracts magnetic particles on an external surface of the hollow structure using the magnetic field. The external surface of the hollow cylindrical structure is provided with a plurality of elliptical depressions. The depressions include first type depressions and second type depressions. A long axis of a first type of elliptical depression is substantially extending in an axial direction of the hollow cylindrical structure, and a long axis of a second type of elliptical depression is substantially extending in a circumferential direction of the hollow cylindrical structure. The external surface of the hollow cylindrical structure has more elliptical depressions of the second type than elliptical depressions of the first type.