Abstract
A linear drive for pigmentation devices, comprising a stator, an air gap which is provided in the stator and is formed so as to be offset in a defined manner, an electric coil within the stator, said coil being designed to produce a concentration of the magnetic flux in the air gap as a result of the coil being energized, an armature which is designed to carry out sliding axial movements in the stator, and a permanent magnet which is captively connected to the armature.
Claims
1-6. (canceled)
7. A pigmentation device with a linear drive, comprising: a stator and an air gap which is provided in the stator and is formed so as to be offset in a defined manner; an electric coil within the stator, said coil being configured to produce a concentration of the magnetic flux in the air gap as a result of the coil being energized, an armature which is designed to carry out sliding axial movements in the stator, and a permanent magnet which is fixedly connected to the armature, wherein the linear drive is configured to move the armature, in response to the coil being energised and the electromagnetic field concentrated in the air gap, mainly by means of magnetic repulsion acting on the permanent magnet, from a rest position in which, when the coil is de-energised, the permanent magnet holds the armature by magnetic attractive forces to the stator, into an extended position in which the armature performs a reversal of its extension movement, wherein at a time of the reversal of the extension movement the coil is de-energised and the armature reverses its extension movement in order to return to the rest position due to the attractive forces of the permanent magnet, and a thickness of a stop, on which the permanent magnet and the stator lie in the rest position, is dimensioned in such a way that in the rest position the magnetic attractive forces of the permanent magnet acting on the stator are overcome by energising the coil only shortly prior to reaching the maximum electromagnetic counter-force, i.e. of the maximum operating current, and the energy which is then stored in the permanent magnet at this release point is abruptly freed and extends the armature out of the stator with a high degree of acceleration.
8. The pigmentation device according to claim 7, wherein a control of an extension speed of the armature, with which the armature extends from the stator, is effected by means of a switch-on duration of the coil being energised, and the switch-on duration is always terminated in time during an inductive rise of the coil current.
9. The pigmentation device according to claim 7, wherein a non-harmonic periodic oscillation of the armature is effected by the coil always being de-energized before the extended position of the armature is reached, so that the retraction movement of the armature, with which the armature returns to the rest position, is largely constant and becomes independent of the controlled extension movement of the armature via the energisation of the coil.
10. The pigmentation device according to claim 7, wherein the non-energized path/time characteristic curve of the retraction movement of the armature, when the coil is de-energised, caused by the permanent magnet force/path characteristic curve of the magnetic attractive forces between the permanent magnet and the stator, is formed by shaping the stator geometry and the magnetically effective mass of said stator in such a way that the retraction time of the armature is minimised.
11. Use of the pigmentation device according to claim 7 for application of Permanent Make-Up (PMU).
Description
EXEMPLARY EMBODIMENT OF THE INVENTION
[0023] Further advantages, features and details of the invention result from the following description of a preferred exemplary embodiment of the linear drive for pigmentation devices as well as from the drawings:
[0024] FIG. 1 a schematic representation of a linear drive for pigmentation devices according to the invention in rest position with non-energized coil 2.
[0025] FIG. 2 an enlarged schematic representation of the air gap formed so as to be offset according to the invention of the linear drive for pigmenting devices at the moment of energizing the coil 2.
[0026] FIG. 3 a schematic representation of the linear drive for pigmentation devices according to FIG. 1, at the time of the reversal point of the extension movement with non-energized coil 2.
[0027] FIG. 1 schematically shows an example of a linear drive for pigmentation devices according to the invention in rest position without electrical control of the coil 2. The permanent magnet 6, which is captively connected to the armature 5, is in contact with the stop 3 due to its magnetic attractive forces to the ferromagnetic stator 1. The thickness of the stop 3 is so dimensioned that in the rest position the permanent magnet 6 assumes an axially central position relative to the opening of the stator 1 and that the magnetic attractive force of the permanent magnet 6 on the stator 1 is overcome by energizing the coil 2 only shortly before the maximum operating current is reached and therefore energy storage takes place in the permanent magnet 6, which is used for advantageous operation of the linear drive for pigmentation devices. The stop 4 prevents the armature 5 from falling out of the stator 1 and limits the stroke of the linear drive.
[0028] FIG. 2 shows an enlarged schematic representation of the air gap so formed as to be offset according to the invention at the time of energizing the current in the coil 2, which due to the inductance of the coil 2 increases exponentially and causes a magnetic field 9 in the air gap 7 which also increases exponentially. Due to the arrangement of the air gap 7, which is provided and formed so as to be offset in a defined manner, the electromagnetic field 9 flows through the permanent magnet 6 in a manner that is favorable for the generation of a repulsive force with a high degree of efficiency and, due to the concentration of the largest part of the magnetic energy in the air gap 7, taking into account the energy storage in the permanent magnet 6 described in [19], generates an almost abrupt repulsion of the permanent magnet 6 by the electromagnetic force 9, so that the permanent magnet 6 together with the armature 5 is extended to the stop 4 with high acceleration similar to the known snap action effect, which leads to the advantageous high prick-in velocities. The sum of the moving masses of armature 5, magnet 6 and pricking means 8 amounts to few grams, so that the armature 5 undergoes high degree of acceleration even with low forces and achieves high velocities despite the small stroke of, for example, 2 mm, and the small total mass has an advantageous effect on the vibrations of the entire system. The braking force component 10 applied to the ferromagnetic stator 1 by the attractive force of the permanent magnet 6 during extension is arranged to be degressive, so that this braking force decreases disproportionately with the distance of the magnet 6 from the stator 1, resulting in a substantially higher end speed of the armature 5 when it hits the stop 4 than is the case with the sinusoidal drives of the prior art. The variation of the speed of an extension movement is controlled via the switch-on time of the coil, which, however, contrary to the prior art, is always terminated temporally within the inductive rise of the coil current, with the advantage of being able to control the entire setting range already during the short rise. In this way, the extension speed and the pricking frequency can be advantageously predetermined for pigmentation in the factory and set by the user on the pigmentation device.
[0029] FIG. 2 shows the linear drive according to FIG. 1 at the time of the reversal point with non-energized coil 2, i.e. at the time when the armature has just changed its direction of movement to return to the rest position. The established degressive characteristic curve of the course of the permanent magnetic restoring force 10 has had an advantageous effect on a decreasing reduction of the extension speed of the armature 5 during the extension. During retraction of the armature 5, the previously degressive braking force 10 now has a progressively accelerating effect on the armature 5 and causes a return time of the armature 5 to the rest position that remains unaffected by the former extension characteristic curve, so that an advantageous non-harmonic oscillation is generated even with periodic control. For an advantageously quick backward movement of the armature 5 to its rest position, the magnetic force/path characteristic curve between the permanent magnet 6 and the stator 2 can be effected by means of its geometric shape and its ferromagnetic mass.
[0030] The features of the invention disclosed in the foregoing description, the claims and the drawings may be relevant, both individually and in any combination, to the implementation of the invention in its various embodiments.
