A driving mechanism designed to drive in an upward-downward direction a suction nozzle for suction-holding a component is provided in, for example, component transfer apparatuses for handling components such as an electronic component, or manufacturing apparatuses for manufacturing a semiconductor device, a liquid-crystal display device, and others. A linear motor is employed as an element of such the driving mechanism. Demands for this type of linear motor have been increasing year by year. Particularly, there has been a growing need for a high-performance linear motor. To meet such a need, a linear motor, which is suitable for a component transfer apparatus, for example, has been proposed (see, for example, the following Patent Document 1).
Generally, a conventional linear motor has a cuboid housing with a wall thickness sufficient for mechanical strength. The housing contains a plurality of annular-shaped coils each having a hollow hole. These coils are arranged such that central axes of the hollow holes thereof align along a longitudinal direction of the housing to form a stator as a whole. Also, through-holes are formed in each of upper and lower walls of the housing to have a size slightly greater than that a diameter of a driving shaft so as to movably receive the driving shaft. Aligned coils as a stator are fixed to position hollow holes thereof to be concentric to each of the through-holes. The driving shaft as a mover, which is composed of a permanent magnet, is inserted into the through-holes and the hollow holes of the aligned coils to penetrate through the aligned coils concentrically.                Patent Document 1: JP 2006-180645A (FIGS. 5 and 8)        