An electromagnetic vibrator for use in a portable communication device includes a housing including a track directed in a first dimension; a coiling including at least one coil turn, oriented in a second dimension essentially perpendicular to the first dimension, coiled around the track and being arranged to receive an electric voltage; a permanent magnet assembly arranged for motion along the track to which the permanent magnet assembly is tightly fitted; and a ferrofluid mixture placed between the track and the permanent magnet assembly allowing motion of the permanent magnet assembly in the first dimension in dependence of the electric voltage as supplied to the coiling.
1. A portable communication device, comprising:
an electromagnetic vibrator to provide tactile stimuli to a user of the portable communication device, the electromagnetic vibrator including:
a housing having a long axis and comprising a track, directed in a first dimension, formed at an inner surface and along the long axis of the housing,
a coiling comprising at least one coil turn, oriented in a second dimension essentially perpendicular to the first dimension, coiled around an outer surface of the housing, to receive an electric voltage and form a magnetic field,
a permanent magnet assembly to move, guided by a rail associated with the track on or around which said permanent magnet assembly is tightly fitted, responsive to the magnetic field, and
a ferrofluid mixture, applied to a sliding surface interface between the track and the permanent magnet assembly, allowing the movement of the permanent magnet assembly in the first dimension in dependence of the electric voltage as supplied to the coiling, to produce the tactile stimuli; and
a power source to supply the electric voltage to the coiling.
2. The portable communication device according to claim 1 , where the ferrofluid is a low friction ferrofluid mixture comprising:
magnetic or magnetizable nano particles, and
a carrier fluid, in which the magnetic or magnetizable nano particles are dispersed.
3. The portable communication device according to claim 2 , where the nano particles comprise ferrite particles and the carrier fluid comprises an organic carrier fluid.
4. The portable communication device according to claim 1 , where the track comprises a tubular cavity directed in the first dimension and in which tubular cavity the permanent magnet assembly is to move.
5. The previously presented portable communication device according to claim 4 , where the tubular cavity has a circular cross section.
6. The portable communication device according to claim 4 , where the tubular cavity is linear in shape.
7. The portable communication device according claim 4 , where the tubular cavity has a toroidal shape.
8. The portable communication device according to claim 7 , where the coiling is to receive a direct current electric voltage.
9. The portable communication device according to claim 1 , further comprising:
at least a first centering element located within the housing and on a first side of the permanent magnet assembly, along the first dimension, for exerting an alternating attracting and repelling force directed in the first dimension on the permanent magnet assembly.
10. The portable communication device according to claim 9 , further comprising:
a second centering element located on a second side of the permanent magnet assembly along the first dimension, for exerting a centering force directed in the first dimension on the permanent magnet assembly.
11. The portable communication device according to claim 10 , where the first and second centering elements comprise a first and a second spring, respectively, attached on either side of the permanent magnet assembly, for exerting centering forces directed in the first dimension on the permanent magnet assembly.
12. The portable communication device according to claim 10 , where the first and second centering elements comprise a second and a third permanent magnet, respectively, oriented in opposite direction in relation to one another in the first dimension, for exerting centering forces directed in the first dimension on the permanent magnet assembly.
13. The portable communication device according to claim 10 , where the first and second centering elements each comprise an essentially gas tight compartment and where there is an essentially gas tight fit at the contact surface between the permanent magnet assembly and a surface wall of the track.
14. The portable communication device according to claim 9 , where the first centering element comprises a first spring of which a first end is attached to a first end of the permanent magnet assembly, and of which a second end is attached to an inner side of a first end stop of the track.
15. The portable communication device according to claim 14 , where the first and second springs are non-linear in the first dimension.
16. The portable communication device according to claim 1 , where the coiling is to receive an alternating current electric voltage.
17. A mobile phone comprising:
an electromagnetic vibrator to provide tactile stimuli to a user of the mobile phone, the electromagnetic vibrator including:
a housing comprising a track, directed in a first dimension, formed as a protrusion on or a recess in an inner surface and along a long axis of the housing,
a coiling comprising at least one coil turn, oriented in a second dimension essentially perpendicular to the first dimension, around the housing, to receive an electric voltage and form a magnetic field,
a permanent magnet assembly to move, guided by a rail associated with the track, responsive to the magnetic field, and
a ferrofluid mixture, applied to a sliding surface interface between the track and the permanent magnet assembly, allowing the movement of the permanent magnet assembly in the first dimension in dependence of the electric voltage as supplied to the coiling, to produce the tactile stimuli; and
a power source to supply the electric voltage to the coiling.