Component for generating active haptic feedback

Description

[0001] Component for generating active haptic feedback. The present invention relates to a component for generating active haptic feedback. This component is designed to generate feedback to a user when the user exerts a force on the component. Such a component can be used, for example, in a button, e.g., in an instrument control button. The component can generate the active haptic feedback, for example, to inform a user that the settings they have made have been successfully implemented by the component.

[0002] Elements for generating active haptic feedback are familiar, for example, from vibrating alarms in mobile phones. These have unbalanced motors. However, they result in uneven feedback and are also comparatively tall.

[0003] US 2011 / 310055 A1 describes the use of a piezoelectric actuator to generate haptic feedback, with the actuator having separate electrodes for measuring pressure and generating vibration. EP 2434555 A1 shows a piezoelectric component with copper electrodes.

[0004] US 5,729,077 A shows a piezoelectric multilayer component with truncated cone-shaped end caps that can also be configured as a sensor and is connected to a Berlincourt d33 measuring device. US 2006 / 028095 A1 shows a component that can be used as both a sensor and an actuator. US 2015 / 209564 A1 shows another piezoelectric transducer element.

[0005] The object of the present invention is therefore to provide an improved component for generating active haptic feedback.

[0006] This object is achieved by a component according to the present claim 1.

[0007] A component for generating active haptic feedback is proposed, which has a base body with first and second internal electrodes stacked one above the other in a stacking direction, wherein a piezoelectric layer is arranged between each of the internal electrodes, wherein the component is designed to detect a force exerted on the component and to generate active haptic feedback when a force exerted on the component is detected, wherein the haptic feedback is generated by applying an electrical voltage between the first and second internal electrodes, which leads to a change in the length of the base body.

[0008] The feedback is called active feedback because it is generated by the component itself. The feedback is called haptic feedback because a user can perceive it through their sense of touch.

[0009] The change in length of the base body can, in particular, be a change in length in a direction perpendicular to the stacking direction. Such a change in length is also referred to as transverse contraction. The change in length in the direction perpendicular to the stacking direction can occur as a result of the piezoelectric effect that arises in the piezoelectric layers due to the voltage applied between the first and second internal electrodes.

[0010] The component can further be configured to convert the change in length of the base body in a direction perpendicular to the stacking direction into a change in length of the component in the stacking direction. In particular, the change in length of the component in the stacking direction can be perceived by a user as active haptic feedback.

[0011] Because the active haptic feedback is generated by a voltage applied between the first and second internal electrodes, the component offers many degrees of freedom in the design of the active haptic feedback. This can be varied by changing the duration of the voltage application, by changing the magnitude of the applied voltage, or by alternating intervals in which no voltage is applied with intervals in which voltage is applied. In this way, different types of feedback can be defined for different events.

[0012] The first and second internal electrodes may differ in that they are contacted with different external electrodes of the component and that a voltage can be applied between them accordingly.

[0013] The piezoelectric layer can be a lead zirconate titanate ceramic (PZT ceramic). The piezoelectric layers can be polarized such that the change in length of the base body is caused by the application of an alternating voltage between the first and second internal electrodes and the associated piezoelectric effect. The PZT ceramic can also contain Nd and Ni. Alternatively, the PZT ceramic can also contain Nd, K, and optionally Cu. Alternatively, the piezoelectric layers can have a composition containing Pb(Zr x Ti 1-x )O 3 + y Pb(Mn 1 / 3 Nb 2 / 3 )O 3.

[0014] The base body can be a sintered part that contains the internal electrodes and the piezoelectric layers.

[0015] A frustoconical sheet is arranged on a top and / or bottom side of the component. The sheet can be designed to transform a change in length of the base body in a direction perpendicular to the stacking direction into a change in length of the component in the stacking direction. The sheet can serve to amplify a change in length of the base body in the stacking direction that occurs as a result of a transverse contraction of the base body. For this purpose, the sheet can be shaped such that when the edge regions of the sheet are pulled together or apart, a central region of the sheet is significantly raised or lowered. The sheet can contribute to converting the transverse contraction of the base body into a significant change in length in the stacking direction of the component.

[0016] The frustoconical sheet may have an edge region that is attached to the top or bottom of the component. The edge region may be attached to the base body of the component, for example, by gluing, soldering, or welding. The sheet may further have a central region that protrudes from the top or bottom of the base body in the stacking direction. The distance of the central region of the sheet from the top or bottom can change significantly if the base body undergoes transverse contraction as a result of a voltage applied between the internal electrodes.

[0017] The sheet contains titanium or can be made of titanium.

[0018] Titanium has particular advantages for the application of the component to create an active haptic

[0019] Feedback offers significant advantages. The component can be used, for example, as a button, generating active haptic feedback when a user presses the button. When such a button is pressed by a human, it is almost inevitable that moisture, such as finger sweat, will remain on the button. This can lead to corrosion. However, titanium is a particularly corrosion-resistant material, so it can effectively protect the component from long-term damage caused by corrosion.

[0020] Furthermore, titanium has a high mechanical strength, so it can extend the service life of the component.

[0021] Furthermore, titanium has a thermal expansion coefficient that is very close to the thermal expansion coefficient of the base body. As a result, the connection point between the sheet and the base body is not subjected to significant mechanical stress when the temperature changes. For example, both the sheet and the base body can have a thermal expansion coefficient between 8 and 9 ppm / K. Furthermore, the component has a measuring unit for measuring a voltage generated between the first and second internal electrodes as a result of the force exerted on the base body. The component is designed to detect the force exerted on the component based on the values ​​recorded by the measuring unit.

[0022] The measuring unit is further configured to detect the magnitude of the force exerted on the component. For this purpose, several threshold values ​​for the voltage generated between the first and second internal electrodes are defined in the measuring unit, and the measuring unit is configured to check which of these threshold values ​​have been exceeded.

[0023] The first and second internal electrodes can therefore perform a dual function in the component. On the one hand, they can be used to detect a force applied to the component, since in this case a voltage is generated between them, and on the other hand, they can trigger the change in length of the component, which generates the active haptic feedback when an alternating voltage is applied between them.

[0024] Alternatively or additionally, the component may have a third internal electrode connected to a measuring contact. The third internal electrode is not electrically connected to a first external electrode, to which the first internal electrodes are connected, or to a second external electrode, to which the second internal electrodes are connected.

[0025] The component can be configured to measure a voltage generated between the third internal electrode and one of the first internal electrodes, which voltage arises as a result of a force exerted on the base body. The component can be configured to detect the force exerted on the component based on the measured voltage. One of the first internal electrodes can be directly adjacent to the third internal electrode.

[0026] The use of a separate third internal electrode, which is not used to generate a change in the length of the base body but merely serves to detect the voltage applied to the component, can be advantageous for achieving greater sensitivity. For example, the distance between the third internal electrode and the adjacent first internal electrode can be greater than the distances between the adjacent first and second internal electrodes. Accordingly, a higher voltage is present between the third electrode and the adjacent first internal electrode for the same mechanical force, thus reducing the threshold for detecting a force.

[0027] The third internal electrode can be arranged centrally in a stack of first and second internal electrodes in the stacking direction. Such a structure is symmetrical. As a result, the third internal electrode cannot cause interference with the component, and the component's functionality is not impaired.

[0028] Alternatively, the third internal electrode can be arranged in the base body such that all first and second internal electrodes are arranged on one side of the third internal electrode. This configuration ensures that the third internal electrode is adjacent to only one other internal electrode. Accordingly, the area of ​​the component that cannot be actively used to generate the transverse contraction is reduced.

[0029] The base body may have a hole extending in the stacking direction from a bottom side of the base body to a top side of the base body and cutting out a central region of the base body. This allows the capacitance between the first and second internal electrodes to be reduced, thus enabling the component to be operated at lower power.

[0030] The base body can have a round base arranged perpendicular to the stacking direction. Compared to a square base body, the corner areas have been cut off. This can also serve to reduce the capacitance of the base body. If the capacitance of the base body is reduced, less power is required to operate the component.

[0031] The base body can have a base area arranged perpendicular to the stacking direction, the side length of which is between 10 and 30 mm, whereby the base body can have a height of between 0.5 and 2.0 mm in the stacking direction.

[0032] The internal electrodes can be made of copper or copper.

[0033] According to a further aspect, the present invention relates to an arrangement comprising a plurality of stacked components as described above. The components are stacked one above the other in the stacking direction. The length changes of the components in the stacking direction add up to one another, so that a stronger feedback can be generated with the arrangement as a whole, since the length change of the arrangement is many times greater than the length change of an individual component. The central regions of the sheets arranged on a top and bottom side of the components are firmly connected to one another.

[0034] In the following, the present invention is described in more detail with reference to the figures. Figure 1 shows a cross section through a component for generating active haptic feedback according to a first embodiment, Figure 2 shows a perspective view of a component, Figure 3 shows a cross section through the base body of the component, Figure 4 shows a cross section through the base body of a component according to a second embodiment, Figure 5 shows a cross section through a base body of a component according to a third embodiment, Figure 6 shows a piezoelectric layer printed with a first internal electrode, Figure 7 shows a piezoelectric layer printed with a second internal electrode, Figure 8 shows a piezoelectric layer printed with a third internal electrode, Figure 9 shows the base body of a component according to a fourth embodiment.

[0035] Figure 1shows a cross-section through a component 1 for generating active haptic feedback. Figure 2 shows the component 1 in an alternative embodiment in a perspective view.

[0036] The component 1 comprises a base body 2 with first internal electrodes 3 and second internal electrodes 4 stacked one above the other in a stacking direction S. The first internal electrodes 3 are contacted with a first external electrode 5. The second internal electrodes 4 are contacted with a second external electrode 6. The first and second external electrodes 5, 6 are each arranged on a side surface 7 of the base body 2, the surface normal of which extends perpendicular to the stacking direction S. In the Figure 1 In the component 1 shown, the first and second outer electrodes 5, 6 are arranged on opposite side surfaces 5. In the case of the Figure 2In the component 1 shown, the first and second outer electrodes 5, 6 are arranged on the same side surface 7.

[0037] The base body 2 has a low height in the stacking direction S. Furthermore, the base body 2 has a base area 8 whose surface normal is parallel to the stacking direction S. The extent of the base area 8 is significantly greater than the height of the base body 2. This results in a flat and wide base body 2. For example, the maximum extent of the base body 2 in a direction perpendicular to the stacking direction S can be at least ten times as great as the height of the base body 2 in the stacking direction S. Preferably, the extent of the base body 2 in a direction perpendicular to the stacking direction S is at least twenty times as great as the height of the base body 2 in the stacking direction S.

[0038] Furthermore, the base body 2 has piezoelectric layers 9 made of a piezoelectric material, e.g., a PZT ceramic. The piezoelectric layers 9 are arranged between the first and second internal electrodes 3, 4. The piezoelectric layers 9 are polarized such that the application of an electrical voltage between the first and second internal electrodes 3, 4 leads to a transverse contraction of the base body 2, during which the length of the base body 2 changes perpendicular to the stacking direction S.

[0039] The transverse contraction inevitably also leads to a change in length of the base body 2 in the stacking direction S. This change in length in the stacking direction S can be perceived as active haptic feedback by a user of the component 1.

[0040] To further enhance the effect of the length change in the stacking direction S, an upper frustoconical sheet 11 is arranged on an upper side 10 of the component 1. Furthermore, a lower frustoconical sheet 13 is arranged on the underside 12 of the component 1. The upper side 10 and the underside 11 lie opposite each other in the stacking direction S. The surface normals of the upper side 10 and the underside 11 are parallel to the stacking direction S.

[0041] The sheets 11, 13 each have an edge region 14 which is firmly connected to the base body 2. Furthermore, the sheets 11, 13 each have a central region 15. The central region 15 of the upper sheet 11 protrudes from the upper side 10 of the base body 2 and accordingly does not touch it. The central region 15 of the lower sheet 13 protrudes from the underside 12 of the base body 2 and accordingly also does not touch it. The distance between the central region 15 of the upper sheet 11 and the upper side 10 is 0.5 mm in a state in which no force is exerted on the component 1 and no voltage is applied between the first and second internal electrodes 3, 4. The distance between the central region 15 of the lower sheet 13 and the underside 12 is also 0.5 mm in this state.

[0042] The central region 15 of the upper sheet 11 is connected to the edge region 14 of the upper sheet 11 via a connecting region 16. The connecting region 16 has two bending points 17 at which the upper sheet deforms particularly strongly when the edge region 14 is contracted or pulled apart. The lower sheet 13 is constructed in the same way.

[0043] If a voltage is now applied between the first and second internal electrodes 3, 4, which leads to a transverse contraction of the base body 2, the edge regions 14 of the sheets 11, 13 are each pulled radially together, since they are firmly connected to the base body 2. As a result, the central regions 15 of the frustoconical sheets 11, 13 are lifted in the stacking direction, whereby the sheets 11, 13 are bent in particular at the two bending points 17. The central region 15 of the upper sheet 11 is moved in the stacking direction opposite to the central region 15 of the lower sheet 13. As a result, the change in length of the component 1 in the stacking direction S is increased, since the central regions 15 move away from one another.

[0044] If the voltage applied between the first and second internal electrodes 3, 4 is reversed, the edge regions of the sheets 11, 13 are moved radially away from each other. This causes the two middle regions 15 of the sheets 11, 13 to move toward each other.

[0045] In this way, the transverse contraction of the base body 2 can be transformed into a change in length of the base body 2 in the stacking direction. For example, a component 1 with a height of less than 2.5 mm can experience a deflection of approximately 100 µm in the stacking direction S in this way. It would not be possible to achieve a change in length in the stacking direction S of this magnitude with a component 1 of this height solely due to a piezoelectric effect acting directly in the stacking direction S.

[0046] Figure 3 shows a simplified cross-section through the base body 2 of the component 1 according to the first embodiment. In Figure 3The first and second internal electrodes 3, 4 arranged in the base body 2 are shown. These are stacked alternately one above the other in the stacking direction S.

[0047] The component 1 is designed to detect a force acting on the component 1. The component 1 can, for example, be designed as a button that can be pressed by a user. In doing so, the user exerts a force on the top side 10 of the component 1. This deforms the component 1. In particular, the component 1 is compressed in the stacking direction S. As a result, an electrical voltage is generated in the piezoelectric layers 9. This electrical voltage is then applied between the first and second internal electrodes 3, 4.

[0048] The component 1 is further connected to a measuring unit 18 and a control unit 19. These are in Figure 3indicated schematically. The measuring unit 18 measures the voltage present between the first and second internal electrodes 3, 4. The control unit 19 is designed to apply an alternating voltage between the first and second internal electrodes 3, 4.

[0049] If no force is applied to component 1, no voltage is present between the first and second internal electrodes 3, 4. However, if a user presses on component 1, an electrical voltage is generated, which is now present between the first and second internal electrodes 3, 4. The voltage between the first and second internal electrodes 3, 4 is continuously measured by measuring unit 18. If measuring unit 18 detects an increase in voltage, it can be concluded that the button has been pressed.

[0050] If the voltage between the first and second internal electrodes 3, 4 exceeds a predefined threshold, the control unit 19 can initiate the generation of active haptic feedback. For this purpose, the control unit 19 applies an alternating voltage between the first and second internal electrodes 3, 4. Due to the piezoelectric effect, the alternating voltage leads to a transverse contraction of the component 1 and a related change in length in the stacking direction S, which is perceived as feedback.

[0051] The measuring unit 18 is further configured to detect the magnitude of the force exerted on the component 1. For this purpose, several threshold values ​​for the voltage generated between the first and second internal electrodes 3, 4 are defined in the measuring unit 18, and it checks which of these threshold values ​​have been exceeded. The control unit 19 can further be configured to initiate the generation of feedback, the precise configuration of which depends on the magnitude of the applied force. The magnitude and duration of the applied alternating voltage can be varied.

[0052] Figure 4shows a cross-section through a base body 2 of a component 1 according to a second exemplary embodiment. The component 1 has a third internal electrode 20. The third internal electrode 20 is connected neither to the first external electrode 5 nor to the second external electrode 6. Instead, the third internal electrode 20 is connected to an additional measuring contact (not shown), which is also arranged on the side surface 7 of the base body 2. The third internal electrode 20 serves to detect a force exerted on the base body 2. For this purpose, the voltage applied between the third internal electrode 20 and the two first internal electrodes 3 adjacent to it is monitored by the measuring unit 18. If a force is exerted on the base body 2, a voltage is generated between these internal electrodes 3, 20.

[0053] The third internal electrode 20 is arranged centrally in a stack of first and second internal electrodes 3, 4. The component 1 has a symmetrical structure. The distance between the third internal electrode 20 and the adjacent first internal electrode 3 is greater than the distances between the adjacent first and second internal electrodes 3, 4. Due to the greater distance, a higher voltage is generated between the third internal electrode 20 and the adjacent first internal electrodes 3 than between a first and an adjacent second internal electrode 3, 4 when a force is exerted on the component 1. This can increase the measurement sensitivity, since even small forces can be sufficient to generate voltages that can be detected by the measuring unit 18.

[0054] Figure 5shows the base body 2 of a component 1 according to a third exemplary embodiment. The third exemplary embodiment differs from the second exemplary embodiment in the arrangement of the third internal electrode 20. The third internal electrode 20 is the internal electrode arranged closest to the underside 12 of the base body 2. The stack has only one piezoelectric layer 9 with an increased thickness, so that the overall height of the stack can be reduced or that more internal electrodes can be arranged in the component 1 with the same stack height.

[0055] However, component 1 is now not constructed symmetrically. If an electrical voltage is applied between the first and second internal electrodes 3, 4, the piezoelectric effect may cause component 1 to bend.

[0056] The Figures 6 to 8each show a printing image of a piezoelectric layer 9. Figure 6 shows a piezoelectric layer 9 on which a first internal electrode 3 is printed. Figure 7 shows a piezoelectric layer 9 on which a second internal electrode 4 is printed. Figure 8 shows a piezoelectric layer 9 on which a third internal electrode 20 is arranged.

[0057] Each inner electrode has a contact bridge 21, via which the inner electrode is electrically connected to one of the outer electrodes 5, 6 or to the measuring contact. The first inner electrode 3, the second inner electrode 4, and the third inner electrode 20 differ in the arrangement of the respective contact bridges 21.

[0058] Apart from the respective contact bridge 21, the internal electrodes 3, 4, 20 are set back from the side surfaces of the base body 2. Accordingly, insulation zones 22 are arranged here. The insulation zones 22 do not experience any transverse contraction when an alternating voltage is applied between the first and second internal electrodes 3, 4. This can lead to mechanical stresses in the component 1, which are also referred to as a clamping effect. These mechanical stresses can reduce the change in length of the component 1 in the stacking direction S and can cause damage to the component 1. Therefore, the insulation zones 22 have a narrow width to minimize this effect.

[0059] Figure 9shows a perspective view of a base body 2 of a component 1 according to a fourth exemplary embodiment. The base body 2 has a hole 23 that extends in the stacking direction from the bottom 12 of the base body 2 to the top 10 of the base body. The hole 23 thus cuts out a central region of the base body 2. In this way, the areas and thus the capacitance between the first and second internal electrodes 3, 4 are reduced.

[0060] The base body 2 further has a round base surface 8 arranged perpendicular to the stacking direction S. List of reference symbols

[0061] 1 Component 2 Base body 3 First inner electrode 4 Second inner electrode 5 First outer electrode 6 Second outer electrode 7 Side surface 8 Base surface 9 Piezoelectric layer 10 Top side 11 Upper frustoconical sheet 12 Bottom side 13 Lower frustoconical sheet 14 Edge area 15 Middle area 16 Connection area 17 Bending point 18 Measuring unit 19 Control unit 20 Third inner electrode 21 Contact bridge 22 Insulation zone 23 Hole Stacking direction

Claims

1. Component (1) for generating active haptic feedback, comprising a main body (2) having first and second internal electrodes (3, 4) stacked one above another in a stacking direction (S), wherein a respective piezoelectric layer (9) is arranged between the internal electrodes (3, 4), wherein the component (1) is configured to identify a force exerted on the component (1), wherein the component (1) is configured to generate active haptic feedback if a force exerted on the component (1) is identified, and wherein the haptic feedback is generated by virtue of an electrical voltage being applied between the first and second internal electrodes (3, 4), said electrical voltage resulting in a change in length of the main body (2), wherein a frustoconical metal sheet (11, 13) is arranged on a top side (10) and / or an underside (12) of the component (1), wherein the component (1) comprises a measuring unit for measuring a voltage which is generated between the first and second internal electrodes (3, 4) and which arises on account of the force exerted on the component (1), and wherein the measuring unit is configured to identify the magnitude of the force exerted on the component (1), for which purpose, in the measuring unit, a plurality of threshold values for the voltage generated between the first and second internal electrodes (3, 4) are defined, and wherein the measuring unit is configured to check in each case which of said threshold values are exceeded.

2. Component (1) according to Claim 1, wherein the frustoconical metal sheet (11, 13) comprises an edge region secured on the top side (10) and / or respectively the underside (12) of the component (1), and wherein the frustoconical metal sheet (11, 13) comprises a central region (15) projecting from the top side (10) and / or respectively the underside (12) in the stacking direction (S).

3. Component (1) according to either of the preceding claims, wherein the metal sheet (11, 13) comprises titanium.

4. Component (1) according to any of the preceding claims, furthermore comprising a third internal electrode (20), which is connected to a measurement contact.

5. Component (1) according to Claim 4, wherein the component (1) is configured to measure a voltage which is generated between the third internal electrode (20) and one of the first internal electrodes (3) and which arises on account of a force exerted on the component (1), and wherein the component (1) is configured to identify the force exerted on the component (1) on the basis of the measured voltage.

6. Component (1) according to either of Claims 4 and 5, wherein the third internal electrode (20) is arranged centrally in the stacking direction (S) in a stack of first and second internal electrodes (3, 4).

7. Component (1) according to either of Claims 4 and 5, wherein the third internal electrode (20) is arranged in the main body (2) in such a way that all first and second internal electrodes (3, 4) are arranged on one side of the third internal electrode (20).

8. Component (1) according to any of the preceding claims, wherein the main body (2) comprises a hole (23) extending in the stacking direction (S) from an underside (12) of the main body (2) to a top side (10) of the main body (2).

9. Component (1) according to any of the preceding claims, wherein the main body (2) comprises a base surface (8) arranged perpendicularly to the stacking direction (S), said base surface being round.

10. Component (1) according to any of Claims 1 to 8, wherein the main body (2) comprises a base surface (8) arranged perpendicularly to the stacking direction (S), the side lengths of said base surface being between 10 and 30 mm.

11. Component (1) according to any of the preceding claims, wherein the main body (2) has a height of between 0.5 and 2.0 mm in the stacking direction (S).

12. Component (1) according to any of the preceding claims, wherein the internal electrodes (3, 4, 20) comprise copper.

13. Arrangement comprising a plurality of components (1) according to any of the preceding claims which are stacked one above another.