Motor

#The present invention claims priority under 35 U.S.C. §119 to Japanese Application No. 2006-73791 filed Mar. 17, 2006, which is incorporated herein by reference.

#The present invention relates to a motor which may be used for driving a lens in a camera or the like and, more specifically, to a small motor which is provided with a bearing that is movable in a thrust direction.

#Small motors have been conventionally used for driving a lens of a digital camera and a video camera, and the like. It has been known to use a motor with a bearing which is movable in a thrust direction as well as a motor without a movable bearing.

#Embodiments will now be described, by way of example only, with reference to the accompanying drawings which are meant to be exemplary, not limiting, and wherein like elements are numbered alike in several FIGURES, in which:

#FIG. 1 is a cross-sectional view showing a motor in accordance with an embodiment of the present invention.

#FIG. 2 is a cross-sectional view showing a conventional motor.

#A motor in accordance with an embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a motor in accordance with an embodiment of the present invention. In this embodiment, the present invention is applied to a stepping motor but it is not limited to the stepping motor.

#As shown in FIG. 1, a stepping motor 20 in accordance with an embodiment of the present invention includes a rotor 24 having a rotor shaft 21 and a permanent magnet 23 which is fixed to an end part 22 of the rotor shaft 21, a stator 25 which is disposed around the rotor 24, a slide bearing 26 for supporting an shaft end 19 of the rotor shaft 21, a bearing holder 27 which movably holds the slide bearing 26 in a thrust direction, and a pressurization apply member 28 which is provided on an outer side in an axial direction of the bearing holder 27.

#An output shaft 29 protruding on the other side from the stator 25 is formed in the rotor shaft 21 and a lead screw is formed in an outer periphery of the output shaft 29. A screw part (not shown) of a head member in an apparatus to which the stepping motor 20 is mounted is threadedly engaged with the lead screw. The screw part of the head member is movable in the axial direction, i.e., a right and left direction in FIG. 1, by rotating the output shaft 29. An outer diameter of the end part 22 of the rotor shaft 21 is formed thinner or a small diameter than an outer diameter of the output shaft 29 and the permanent magnet 23 is fixed to the end part 22 which is the small diameter portion. Further, the rotor shaft 21 is formed with a recessed part 30 having a conical recessed face at a shaft end of the end part 22 and a shaft end 18 of the output shaft 29 is formed in a convex curved face. Alternatively, the shaft end 18 of the output shaft 29 may be formed in a recessed part having a conical recessed face in the same way as the end part 22 of the rotor shaft 21 and a steel ball is disposed between the thrust bearing 46 and the shaft end 18.