Touch-sensitive input device with electromagnetic actuator operated at maximum magnetization
A touch-sensitive input device includes a support, an input part with a touch-sensitive input surface, an elastic device which bears the input part at the support, an electromagnetic actuator which acts between the input part and the support to produce a deflection of the input part out of a resting position, and control electronics. The electromagnetic actuator comprises a coil with a cavity, a core arranged at least in part in the cavity, and an armature arranged outside the cavity. The core generates a magnetic field defining a pole direction. The armature interacts with the magnetic field. The control electronics generate an electrical control signal for the coil to produce the deflection of the input part out of the resting position and to provide a maximum deflection of the input part. A duration of the electrical control signal is limited so as to provide, after the deflection, a haptic feedback.
1. A touch-sensitive input device comprising:
a support;
an input part comprising a touch-sensitive input surface;
an elastic device configured to bear the input part at the support along a deflection direction so that the input device is elastically reset and is oscillatively movable;
an electromagnetic actuator configured to act between the input part and the support so as to produce a deflection of the input part out of a resting position, the deflection comprising at least one effective direction having an effective direction component that is parallel to the deflection direction, the electromagnetic actuator comprising,
a coil which is configured to define a cavity,
a ferromagnetic core which is arranged at least in a region in the cavity, the ferromagnetic core being configured to generate a magnetic field defining a pole direction, and
a ferromagnetic armature which is configured to interact with the magnetic field and which is arranged outside the cavity; and
control electronics configured to generate an electrical control signal for the coil of the electromagnetic actuator so that the coil of the electromagnetic actuator, after a detection of a contact of the input part and/or after a detection of an actuation of the input part by an actuation force sensor, is charged with the electrical control signal so as to produce the deflection of the input part out of the resting position and to provide a maximum deflection of the input part,
wherein,
a duration of the electrical control signal is limited so as to provide, after the deflection, a return of the input part to the resting position or an oscillation of the input part around the resting position along the deflection direction, thereby respectively generating a haptic feedback;
the electrical control signal and the ferromagnetic armature are selected so that, along an imaginary line passing through the ferromagnetic armature in the pole direction, a maximum deflection along a curve of a line is achieved at the latest when a maximum magnetization of the ferromagnetic armature is achieved, and
the maximum magnetization is at least 90% of a material-specific saturation magnetization.
2. The touch-sensitive input device as recited in claim 1 , wherein the input part is a touchpad or a touchscreen.
3. The touch-sensitive input device as recited in claim 1 , wherein the maximum magnetization is present in >20% of a total volume of the ferromagnetic armature.
4. The touch-sensitive input device as recited in claim 1 , wherein the duration of the electrical control signal does not exceed 5 ms.
5. The touch-sensitive input device as recited in claim 1 , wherein the maximum magnetization of the ferromagnetic armature is achieved in a time interval between first achieving half of the maximum deflection along the curve of the line and between first achieving the maximum deflection along the curve of the line.
6. The touch-sensitive input device as recited in claim 1 , wherein the ferromagnetic core is formed with an E-shape.
7. The touch-sensitive input device as recited in claim 1 , wherein the ferromagnetic core comprises multiple layers arranged in a stack.
8. The touch-sensitive input device as recited in claim 1 , wherein,
an air gap is formed between ferromagnetic armature and the ferromagnetic core, and
the air gap comprises a clearance of from 0.7 mm to 1.3 mm between the ferromagnetic armature and the ferromagnetic core in the resting position of the input part.
9. The touch-sensitive input device as recited in claim 8 , wherein a dimension of the ferromagnetic armature in the pole direction is smaller than the clearance of the air gap.
10. The touch-sensitive input device as recited in claim 1 , wherein the ferromagnetic armature is made of a solid material.
11. The touch-sensitive input device as recited in claim 1 , wherein,
the ferromagnetic armature is attached at the input part, and
the input part is formed from non-ferromagnetic materials in a region adjoining the ferromagnetic armature.
12. The touch-sensitive input device as recited in claim 1 , wherein the deflection direction is substantially parallel to the touch-sensitive input surface.
13. The touch-sensitive input device as recited in claim 1 , wherein a dimension of the ferromagnetic armature in the pole direction is < 1/10 th of a dimension of the ferromagnetic core in the pole direction.
14. The touch-sensitive input device as recited in claim 1 , wherein a dimension of the ferromagnetic armature in the pole direction is from 0.9 mm to 1.1 mm.
15. A method of using the touch-sensitive input device as recited in claim 1 in a motor vehicle, the method comprising:
providing the touch-sensitive input device as recited in claim 1 ;
incorporating the touch-sensitive input device in the motor vehicle; and
using the touch-sensitive input device so as to generate a haptic feedback.
16. The method as recited in claim 15 , wherein the touch-sensitive input device is incorporated in a center console of the motor vehicle.
17. A method for controlling a touch-sensitive input device, the method comprising:
providing a touch-sensitive input device comprising:
a support;
an input part comprising a touch-sensitive input surface,
an elastic device configured to bear the input part at the support along a deflection direction so that the input device is elastically reset and is oscillatively movable;
an electromagnetic actuator configured to act between the input part and the support so as to produce a deflection of the input part out of a resting position, the deflection comprising at least one effective direction having an effective direction component that is parallel to the deflection direction, the electromagnetic actuator comprising,
a coil which is configured to define a cavity,
a ferromagnetic core which is arranged at least in a region in the cavity, the ferromagnetic core being configured to generate a magnetic field defining a pole direction, and
a ferromagnetic armature which is configured to interact with the magnetic field and which is arranged outside the cavity, and
control electronics configured to generate an electrical control signal for the ferromagnetic actuator;
charging the coil of the electromagnetic actuator with the electrical control signal generated by the control electronics after a detection of a contact of the input part and/or after a detection of an actuation of the input part by an actuation force sensor, so as to produce the deflection of the input part out of the resting position and to achieve a maximum deflection of the input part,
wherein,
a duration of the electrical control signal is limited so as to provide, after the deflection, a return of the input part to the resting position or an oscillation of the input part around the resting position along the deflection direction, thereby respectively generating a haptic feedback;
the electrical control signal and the ferromagnetic armature are selected so that, along an imaginary line passing through the ferromagnetic armature in the pole direction, a maximum deflection along a curve of a line is achieved at the latest when a maximum magnetization of the ferromagnetic armature is achieved, and
the maximum magnetization is at least 90% of a material-specific saturation magnetization.
18. The method as recited in claim 17 , wherein the maximum magnetization is present in >20% of a total volume of the ferromagnetic armature.
19. The method as recited in claim 17 , wherein the duration of the electrical control signal does not exceed 5 ms.
20. The method as recited in claim 17 , wherein the maximum magnetization of the ferromagnetic armature is achieved in a time interval between first achieving half of the maximum deflection along the curve of the line and between first achieving the maximum deflection along the curve of the line.