| 摘要 |
The present application discloses a compass having a base, a pivot extending from the base along an axis and a pointer. The pointer includes a central portion resting upon the pivot, a first outer portion radially spaced from the axis of the pivot and having a magnetic north polarity and second outer portion radially spaced from the axis of the pivot and angularly spaced from the first outer portion by approximately 180 degrees. The second outer portion has a magnetic south polarity. The central portion, the first outer portion and the second outer portion are integrally formed as part of a single unitary body including polymeric material. In one exemplary embodiment, the central portion, the first outer portion and the second outer portion are formed from a magnetic powder blended with a polymer matrix. In another exemplary embodiment, the first portion and the second portion include at least one magnetic member encapsulated within a layer solely composed of the polymeric material. In one exemplary embodiment, the compass further includes a bearing partially encapsulated within the central portion such that the bearing rests upon the pivot. The present application also discloses a method for forming the aforementioned compass which includes steps of providing a base, forming a pivot extending from the base along an axis, mixing a magnetic powder with a fluid polymer, molding the mixture of magnetic powder and fluid polymer so as to form a single unitary body having a central portion and first and second opposite portions radially spaced from the central portion, magnetizing the first and second opposite portion so as to have opposite magnetic polarities and resting the central portion upon the pivot. According to one exemplary embodiment, a plurality of compasses having varying sensitivities may be made by varying a ratio of the magnetic powder to the polymeric material.
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