Haptic device

Abstract

A haptic device (100) is specified, comprising a piezoelectric actuator (1), a base body (10), and at least one reinforcing element (30) on a first main surface (11) of the piezoelectric actuator (1), wherein the at least one reinforcing element (30) has at least one fastening area (39) with which the at least one reinforcing element (30) is attached to the base body (10), and a stroke area (31) which is spaced apart above the first main surface (11), wherein a connecting layer (20) is arranged between the at least one fastening area (39) and the first main surface (11).

Description

[0001] A haptic device is described. Such a device comprises an actuator capable of generating and / or detecting movement. For example, the haptic device may be coupled with a movable element, such as a touch-sensitive surface or the tip of a pen-like device. The actuator may be, for example, a piezoelectric actuator, or in particular, a piezoceramic actuator.

[0002] The haptic device can be designed, for example, to generate haptic feedback upon touch. The haptic device can be used, for instance, in a touchscreen, trackpad, push button, or stylus (pen-like device). Furthermore, the haptic device can be used in the automotive industry.

[0003] Devices for generating haptic feedback are known from publications WO 2017 / 032 868 A1, WO 2018 / 046 201 A1, WO 2020 / 011 403 A1 and WO 2021 / 019 083 A1, in which a reinforcing element for stroke amplification is attached to a piezoelectric actuator. The reinforcing element is, for example, in the form of a metal sheet. Reliable attachment of the reinforcing element is of particular importance here.

[0004] At least one function of certain embodiments is to specify a haptic device.

[0005] This problem is solved by an object according to the independent patent claim. Advantageous embodiments and further developments of the object are characterized in the dependent claims and are further described in the following description and drawings.

[0006] According to at least one embodiment, a haptic device is specified. For example, the haptic device can be configured to detect haptic input. Furthermore, the haptic device can also be configured to output haptic feedback. In other words, the haptic device can, for example, be configured so that a haptic signal from a user can be received by the haptic device. Furthermore, the haptic device can be configured so that a haptic signal can be output to a user. In particular, the haptic device can thus be configured to generate haptic feedback. The haptic device can therefore be configured to provide perceptible feedback to a user for certain actions or inputs.

[0007] The haptic device preferably comprises a piezoelectric actuator. The piezoelectric actuator can be configured to detect haptic input and / or to output haptic feedback. The piezoelectric actuator can be based on a piezoelectric material, in particular a piezoelectric ceramic material or a piezoelectric polymer material. The piezoelectric actuator can have a base body containing the piezoelectric material. In the following, the term "piezoelectric actuator" can refer to both the base body and vice versa.

[0008] Furthermore, one or more electrodes can be provided on and / or within the base body. If no electrodes are present in the base body, i.e., if the base body has no internal electrodes, the piezoelectric actuator can be designed as a monolithic actuator, for example, as a disk or plate. Alternatively, the piezoelectric actuator can have at least one or more internal electrodes. In this case, the base body of the piezoelectric actuator can be constructed in a multilayer design with multiple piezoelectric layers arranged along a stacking direction and the internal electrodes.

[0009] The base body, and thus the piezoelectric actuator, can preferably be cuboid in shape and have a longitudinal direction. For example, the longitudinal direction can correspond to the direction with the greatest extent of the base body. If the base body is constructed in multiple layers, the longitudinal direction can preferably be perpendicular to the stacking direction.

[0010] By applying a suitable electrical signal, the piezoelectric actuator can undergo a change in its dimensions in at least one direction, whereby this change can be part of the haptic signal. Applying an alternating voltage can generate a periodic change and thus a vibration. In particular, the change in the dimensions of the piezoelectric actuator can be caused at least by the d31 effect and correspond at least to a change in the length of the piezoelectric actuator along its longitudinal direction. Conversely, a mechanical action, caused by haptic input, can induce a change in the dimensions of the base body in at least one direction, particularly preferably the longitudinal direction. Due to the inverse piezoelectric effect, this change in dimensions can generate an electrical voltage in the piezoelectric material, which can be detected, for example, via the internal electrodes.

[0011] The use of a piezoelectric actuator for detecting and / or generating a haptic signal offers significant advantages. A piezoelectric actuator has a short response and decay time. Accordingly, the time and duration of the haptic signal detection or generation can be determined very precisely. Furthermore, when generating a haptic signal, varying the control signal applied to the piezoelectric actuator—for example, in terms of frequency, voltage, pulse rate, and signal type—determines the amplitude, frequency, and duration of the piezoelectric actuator's vibration. Different control signals make it possible to generate different haptic signals.

[0012] According to a further embodiment, the haptic device has at least one mechanical reinforcing element, which is hereinafter referred to simply as at least one reinforcing element. The at least one reinforcing element is attached to the piezoelectric actuator. In particular, the at least one reinforcing element can be attached to the piezoelectric actuator in such a way that a change in the extension of the piezoelectric actuator in at least one direction deforms the at least one reinforcing element and thus moves at least some areas of the first reinforcing element. Particularly preferably, the at least one reinforcing element can be attached to the piezoelectric actuator in such a way that a change in the length of the piezoelectric actuator, and in particular of the base body, at least along its longitudinal direction, moves an area of ​​the at least one reinforcing element in a direction perpendicular to the longitudinal direction.Furthermore, a direction is also possible that forms an angle with the longitudinal direction greater than 0° and less than 90°. In other words, a section of at least one reinforcing element can be moved in a direction oblique to the longitudinal direction.

[0013] In particular, the base body can have a first main surface and a second main surface opposite the first main surface. The first main surface and the second main surface can each have a main extension direction that runs parallel to the longitudinal direction. The arrangement direction from the first main surface to the second main surface, which in a multi-layered base body can preferably coincide with the stacking direction, is particularly preferably perpendicular to the longitudinal direction. The at least one reinforcing element can preferably be applied to and attached to one of the main surfaces. Without being intended as a limitation, it is assumed below that if the haptic device has only one reinforcing element, this element is arranged on the first main surface of the base body.

[0014] The basic body can further have side surfaces that connect the first and second main surfaces. In particular, the basic body can have two opposing longitudinal side surfaces. Furthermore, the basic body can have two opposing end faces. The longitudinal side surfaces extend along the longitudinal direction, while the end faces are preferably oriented perpendicular to the longitudinal direction.

[0015] The at least one amplification element can comprise a first mechanical amplification element, hereinafter referred to as the first amplification element, which is applied and attached to the first main surface of the base body and thus to the first main surface of the piezoelectric actuator. Furthermore, the at least one amplification element can comprise at least a second mechanical amplification element, hereinafter referred to as the second amplification element, which is applied and attached to the second main surface of the base body and thus to the second main surface of the piezoelectric actuator. Thus, the haptic device can particularly preferably include the piezoelectric actuator, which is arranged between the first and second amplification elements.

[0016] The following description is essentially limited to the aforementioned at least one reinforcing element and applies to the first reinforcing element and, if present in the haptic device, also to the second reinforcing element. The features and properties described above and below for the at least one reinforcing element can therefore apply accordingly to the first reinforcing element and, if present in the haptic device, to the second reinforcing element. Preferably, the first reinforcing element and, if present, the second reinforcing element are identical and can thus have the same features and properties. If the haptic device has more than two reinforcing elements, the described features and embodiments apply accordingly.

[0017] The at least one reinforcing element can be made of or comprise metal, for example, steel and / or titanium. For instance, the at least one reinforcing element can be plate-shaped. Furthermore, the at least one reinforcing element can be flat, i.e., a planar plate, which is attached to the piezoelectric actuator by at least one mounting area, which can be, for example, an edge area or an intermediate area, or even across its entire surface. Particularly preferably, the at least one reinforcing element can be a metal bracket, i.e., a metal strip or sheet with a non-planar geometry.The at least one reinforcing element can, for example, be attached to one or two end regions or to two end regions and an intermediate region of a main surface of the base body along the longitudinal direction of the piezoelectric actuator by at least one or preferably at least two attachment areas, which may preferably be edge regions or edge regions and at least one intermediate region of the at least one reinforcing element along the longitudinal direction. Adjacent to one of the attachment areas or between the at least two attachment areas, the at least one reinforcing element has at least one stroke region spaced apart from the piezoelectric actuator. Thus, the at least one reinforcing element can preferably have at least one attachment area by which the at least one reinforcing element is attached to the base body and a stroke region that is spaced apart above the corresponding main surface.If the at least one reinforcing element has more than one fastening area, these areas, as well as the method of fastening each, are preferably designed identically. The features and embodiments described below in connection with at least one fastening area can therefore apply equally to all fastening areas of the at least one reinforcing element.

[0018] According to a further embodiment, a bonding layer is arranged between the at least one mounting area and the first main surface. The mounting of the at least one mounting area to the base body, and thus to the piezoelectric actuator, can therefore preferably be effected by the bonding layer. The bonding layer can particularly preferably comprise an adhesive or be an adhesive layer. Thus, the term "bonding layer" in the following can also refer to the material of the bonding layer, for example, an adhesive. The at least one reinforcing element can therefore preferably be attached to the piezoelectric actuator by an adhesive bond.If at least one reinforcing element is made of or contains titanium, this can offer the advantage that its coefficient of thermal expansion is very similar to that of the piezoelectric actuator, resulting in minimal or no mechanical stress during temperature changes. Consequently, the adhesive bond is subjected to little or no mechanical stress during temperature fluctuations. Furthermore, the bonding layer can also be, for example, a solder layer, a weld layer, or a silver sinter layer.

[0019] A dielectric material can be arranged, for example, between the lifting area of ​​the at least one reinforcing element and the main surface on which the at least one reinforcing element is arranged and attached. The dielectric material can, for example, comprise one or more materials selected from air, plastic film, or plastic foam.

[0020] As described above, at least one amplifying element can convert a change in expansion, and particularly preferably a change in length, of the piezoelectric actuator into a stroke movement perpendicular or oblique to the change in expansion, and preferably to the change in length. Conversely, a mechanically induced change in expansion and / or stroke movement, for example, by a user, can be converted into a change in expansion, and particularly preferably a change in length, of the piezoelectric actuator that is perpendicular or oblique to the change in expansion. In the case of a multi-layer piezoelectric actuator, the direction of the stroke movement can preferably correspond to the stacking direction. The stroke movement can have a significantly larger amplitude than the change in length. For example, the amplitude of the stroke movement can be 5 to 40 times the amplitude of the change in length.By combining the piezoelectric actuator with at least one amplification element, amplification can thus be achieved.

[0021] The at least one reinforcing element can be free of indentations and have a constant wall thickness. Eliminating indentations in the at least one reinforcing element simplifies its manufacture. Furthermore, the at least one reinforcing element can have at least one indentation that reduces its mechanical resistance to deformation. Particularly with a reinforcing element thick enough to require significant force for deformation, the use of indentations can be advantageous, as they facilitate deformation. These indentations can be created using processes such as milling, punching, and / or embossing.

[0022] According to a further embodiment, the haptic device has at least one fastening improvement element, which is designed and configured to increase the reliability of the attachment of the at least one mounting area to the base body. Particularly preferably, the at least one fastening improvement element can be designed and configured to increase the durability of the attachment of the at least one mounting area to the piezoelectric actuator mediated by the bonding layer. Due to the deformation of the piezoelectric actuator and the at least one reinforcement element described above, forces such as shear forces can occur in the area of ​​the bonding layer, which can promote detachment of the at least one mounting area from the piezoelectric actuator.This can be particularly true under harsh conditions such as increased humidity and / or elevated temperature, as these can weaken the bonding layer. The at least one fastening enhancement element can be designed and configured to counteract such delamination effects. The embodiments and features of the at least one fastening enhancement element described below can be present individually or in combination. If the at least one reinforcement element has multiple fastening areas, each of these can have one or more identical or different fastening enhancement elements. Accordingly, the embodiments and features of the at least one fastening enhancement element described below apply equally to all fastening areas of the haptic device.

[0023] According to a further embodiment, the at least one fastening improvement element is part of the at least one reinforcing element. In other words, the fastening improvement element can have or be a structure in or on the at least one reinforcing element that is designed and configured to counteract, for example, the previously described detachment effect promoted by shear forces.

[0024] For example, the at least one fastening improvement element on a mounting surface of the at least one mounting area facing the base body and thus the piezoelectric actuator can have a surface structure in which at least a portion of the bonding layer is arranged. The surface structure can, for example, have or be at least one recess. This at least one recess, which can, for example, form a pocket in the shape of a wedge-shaped recess in the mounting surface, can, for example, locally increase the amount of bonding layer material and thus locally increase the thickness of the bonding layer. The recess can particularly preferably be formed on an edge of the at least one mounting area facing the stroke area.At the edge of the fastening area facing the lifting area, a particularly high tendency for delamination may occur, which can be counteracted by the locally greater thickness of the bonding layer. Furthermore, the fastening improvement element can have a surface-enlarging structure in which at least part of the bonding layer is arranged. This surface-enlarging structure can, for example, have grooves or slots such as longitudinal or transverse grooves. The surface-enlarging structure increases the interface between the fastening surface and the bonding layer, thereby enhancing the bonding effect of the bonding layer.

[0025] Furthermore, the at least one fastening improvement element can have at least one wing element adjacent to the fastening area, wherein the wing element extends at least partially along a side surface of the base body adjacent to the first main surface, particularly preferably a longitudinal side surface. The wing element can be formed integrally with the fastening area and, for example, form a kind of tab or clamp that covers or encloses part of the side surface. Furthermore, the at least one fastening improvement element can have two wing elements that extend at least partially along two opposite side surfaces of the base body, particularly preferably the two longitudinal side surfaces. The at least one wing element can particularly preferably be oriented perpendicular to the fastening surface.

[0026] The bonding layer can be arranged not only between the mounting surface and the main surface of the base body, but also between the at least one wing element and the base body. In other words, the at least one wing element can increase the interface between the at least one reinforcing element and the base body. Furthermore, by arranging the wing element on a side surface of the base body, support can be provided, and a different force distribution can be achieved compared to the mounting area, thus counteracting detachment effects. The at least one wing element can therefore achieve improved and defined force distribution and increased stiffness of the mounting area.Furthermore, as described above, the first and second reinforcement elements can be formed, with the bonding layer additionally arranged between at least one wing element of the at least one reinforcement element and at least the mounting area and / or a wing element of the further reinforcement element. In other words, the two reinforcement elements can be attached to each other by the bonding layer between the respective wing elements and / or mounting areas, thus counteracting detachment effects. Similarly, at least one wing element of the at least one reinforcement element can be attached to the base body and / or the mounting area and / or a wing element of a further reinforcement element by a portion of the bonding layer.Furthermore, the at least one wing element of the at least one reinforcement element can have a toothed structure designed and configured to engage with a complementary toothed structure of a wing element or a mounting area of ​​another reinforcement element. In this case, the connecting layer can preferably also be arranged between the toothed structures of the two reinforcement elements. The toothed structures can be formed, for example, by arranging the wing element, or a part thereof, of one reinforcement element longitudinally next to the wing element, or a part thereof, of the other reinforcement element.

[0027] According to a further embodiment, the fastening enhancement element has, or is itself has, a region of at least one reinforcing element that projects beyond the base body on a side facing away from the stroke area. In other words, the at least one reinforcing element can project beyond the base body on a side facing away from the stroke area. This allows for the protection of an end region of the piezoelectric actuator, and in particular edge protection, preferably along the longitudinal direction.

[0028] According to a further embodiment, the fastening enhancement element has a coating of the at least one fastening area of ​​the at least one reinforcing element with the bonding layer. In other words, the fastening area can be coated with the material of the bonding layer. In particular, the bonding layer can form a cap over the base body and the reinforcing element in the fastening area, so that the fastening area, together with a region of the base body, is coated in the bonding layer.

[0029] According to a further embodiment, the at least one fastening improvement element comprises a prepreg between the first main surface and the fastening area of ​​the at least one reinforcement element, and in particular the fastening surface, which is filled with the material of the bonding layer. A prepreg can, in particular, be a flat, planar textile semi-finished product pre-impregnated with a thermoplastic or thermoset matrix, for example, and comprising one or more unidirectional layers with or consisting of threads, or a woven fabric, or a non-woven fabric with preferably perpendicularly arranged threads. A prepreg can, for example, be a base material for a printed circuit board and preferably comprises a glass fiber fabric impregnated with an epoxy adhesive. By using one or more such layers, the thickness of the bonding layer can be adjusted and thus optimized.

[0030] According to a further embodiment, the fastening improvement element comprises an additional element beyond the at least one reinforcing element. This eliminates the need for any significant modifications to the at least one reinforcing element compared to a haptic device without a fastening improvement element.

[0031] For example, the at least one fastening improvement element can have a clamping device that is slid onto the at least one reinforcing element and the base body in at least one fastening area of ​​the at least one reinforcing element. The clamping device is particularly preferably clamp-shaped, ring-shaped, or cap-shaped. In other words, the clamping device can be a clamping element, a ring element, or a cap element. The clamping device can enclose the at least one fastening area and a part of the base body of the piezoelectric actuator in such a way as to counteract any tendency to detach.

[0032] According to a further embodiment, the fastening improvement element has a conformal coating that encases the haptic device. A conformal coating is defined in particular as a coating that, unlike, for example, a volume potting compound, covers the surfaces of the haptic device with a substantially uniform, thin layer. The conformal coating preferably does not impede the functionality of the covered elements, and the original contour is substantially preserved. The conformal coating can have a thickness of greater than or equal to 1 µm and less than or equal to 5 mm, or less than or equal to 1 mm, or less than or equal to 100 µm, and in particular comprises or consists of a plastic material, for example, based on a silicone or acrylate.The conformal coating, which preferably covers all free surface areas, or all free surface areas except for the outer electrodes, protects the at least one bonding layer from damaging external influences such as moisture, which could lead to degradation of the at least one bonding layer and thus to a deterioration of the attachment of the at least one reinforcing element. The conformal coating can be applied, for example, by dip coating, spray coating, or brush coating.

[0033] According to a further embodiment, the haptic device has a side surface adjacent to the first main surface of the base body, on which at least two external electrodes for electrical contacting the haptic device are arranged. In particular, the at least two external electrodes can be provided and configured for electrically controlling the base body and thus the piezoelectric actuator. The at least two external electrodes can particularly preferably be the only external electrodes of the piezoelectric actuator and all be arranged on the same longitudinal side surface. A flexible connection element, for example a so-called flexible printed circuit board (FPC), can be connected to the at least two external electrodes on the base body. The FPC can have connection points, for example solder contacts or a connector, on a side facing away from the base body.If the haptic device has a conformal coating as described above, this coating can particularly preferably enclose part of the flexible connecting element together with the piezoelectric actuator.

[0034] According to a further embodiment, the piezoelectric actuator in the base body has at least one passive region, i.e., a region that does not participate in length changes of the piezoelectric actuator. The at least one passive region can preferably adjoin the at least one mounting region. The at least one mounting enhancement element can include the passive region or be formed by it. For example, the base body can have internal electrodes, and the passive region can be a region of the base body that is free of any internal electrodes. Similarly, the piezoelectric actuator in the base body can have a plurality of internal electrode layers, and the mounting enhancement element can have a region of the base body in the at least one mounting region that is adjoining the at least one mounting region and is free of internal electrode layers.By having at least one passive area adjacent to the at least one mounting area, a change in length of the piezoelectric actuator in the at least one mounting area can be avoided, thereby reducing or preventing stress forces that could act on the connection layer.

[0035] As previously mentioned, the haptic device described here may preferably incorporate measures that improve its manufacturability and / or service life. Particularly advantageous features and properties are summarized below.

[0036] As described, the outer electrodes can be applied to the same longitudinal side surface instead of the end faces. This can reduce the manufacturing effort for metallizing the outer electrodes by 50%, since both outer electrodes can be applied as contact pads in a single step without having to rotate the base body. A further advantage is the possibility of using a flexible connection element such as an FCP for the electrical connection. Compared to soldered wires, this offers the advantages of being easier to process in mass production, thinner, and lighter, and easier to handle during assembly with a special FPC connector.

[0037] Furthermore, as described, one or more fastening improvement elements can be provided that improve the connection between the reinforcement elements and the piezoelectric actuator, thereby increasing the release forces.

[0038] For example, at least one reinforcement element can be designed to include one or more wing elements that are bent over the corners of the piezoelectric actuator. This can be particularly advantageous when using liquid adhesive as the material for the bonding layers. With this design, it is also possible to connect the two separate reinforcement elements via the bonding layers, preferably by adhesive bonding. This can have the advantage that some of the pull-off and splitting forces acting on the bonding layers cancel each other out. Furthermore, the stiffness of the bonding layers can be increased compared to a flat design of the fastening areas. Increased stiffness reduces the pull-off forces acting on the reinforcement elements, which can represent a critical type of stress on the inside of a fastening area.

[0039] Furthermore, the design, particularly with the wing elements, makes it possible to apply the material for the bonding layers comprehensively around the entire component in the area of ​​the fastening points. This can reduce the likelihood of areas with poor bonding layer coverage and lead to a uniform force distribution within the bonding layers.

[0040] Furthermore, to improve the mechanical connection between the reinforcing element and the base body, at least one clamping device in the form of a bracket, clamp, ring, or cap can be provided, preferably made of or with metal, for example, aluminum, stainless steel, or titanium, and preferably having a similar functionality to the wing elements. In addition to bonding to the piezoelectric actuator, the clamping device can be designed to press the reinforcing element(s) against the base body and maintain the position, for example, solely by friction, such as via a conical internal structure.

[0041] Furthermore, the fastening areas of the reinforcement elements can be modified to form grooves or slots. This shape can lead to an increased amount of material for the bonding layers in general, and to an increased amount in contact with the surface of a reinforcement element, thus strengthening the bond and ensuring a more uniform force distribution. To increase the amount of bonding layer material in the critical area on the inner surfaces of the fastening areas, a recess, for example with a wedge-like shape, can be incorporated into the reinforcement element. Additionally, prepregs can be applied between the base body and the reinforcement elements and filled with bonding layer adhesive to achieve a uniform material distribution in the fastening areas.

[0042] Furthermore, the base body can be designed in such a way that passive areas are created in the area of ​​the mounting points in order to reduce the shear forces that would arise at these points due to the contraction and expansion of the piezoelectric actuator.

[0043] Furthermore, the design with wing elements or clamping devices can protect the piezoelectric actuator from impacts and mechanical contact, as it is completely covered by the material of the connecting layers and reinforcing elements, which are preferably made of metal. This protective function is not limited to a specific type of reinforcing element and can be applied to any shape. In addition, the reinforcing elements can be designed to be flush with the base body, which can also protect the piezoelectric actuator from impacts or shocks.

[0044] To increase the durability of the bonding layers under harsh conditions, a conformal coating can be applied for protection. Specifically, the coating protects the bonding layers from damage and failure. Prior to the coating process, the edges of the substrate can be rounded. This ensures a very uniform coating thickness across the entire component. This uniformity is beneficial for guaranteeing reliable protection against high humidity. In addition to the rounded edges, the viscosity of the coating material itself, such as a resin, is also advantageously matched to the piezoelectric actuator to further improve the wettability of the component edges.

[0045] Further advantages, advantageous embodiments and further developments will result from the exemplary embodiments described below in conjunction with the figures. Fig. 1A and Fig. Figure 1B shows schematic representations of a haptic device according to an exemplary embodiment. Fig. 2A and Fig. 2B shows schematic representations of a haptic device according to further embodiments, Fig. Figures 3A to 3C show schematic representations of a haptic device according to a further embodiment. Fig. Figure 4 shows a schematic representation of part of a haptic device according to a further embodiment, Fig. Figures 5A to 5C show schematic representations of a haptic device according to a further embodiment. Fig. Figures 6A to 6C show schematic representations of a haptic device according to a further embodiment. Fig. Figures 7A to 7G show schematic representations of a haptic device according to a further embodiment. Fig. 8A and Fig. Figure 8B shows schematic representations of a haptic device according to a further embodiment, Fig. Figures 9A to 9C show schematic representations of a haptic device according to a further embodiment. Fig. Figures 10A to 10C show schematic representations of a haptic device according to a further embodiment. Fig. Figures 11A to 11C show schematic representations of a haptic device according to a further embodiment. Fig. Figures 12A to 12C show schematic representations of a haptic device according to a further embodiment. Fig. 13, Fig. 14 to Fig. Figure 15 shows schematic representations of a haptic device according to further embodiments, Fig. Figures 16A to 18C show schematic representations of a haptic device according to a further embodiment.

[0046] In the exemplary embodiments and figures, identical, similar, or similarly functioning elements may be designated with the same reference numerals. The depicted elements and their relative sizes are not to be considered to scale; rather, individual elements, such as layers, components, building elements, and areas, may be exaggerated for clarity and / or better understanding.

[0047] The features and embodiments described in connection with the figures can be combined with one another according to further embodiments, even if not all combinations are explicitly described. Furthermore, the embodiments described in connection with the figures can alternatively or additionally include further features as described in the general section.

[0048] In the Fig. 1A and Fig. Figure 1B shows an embodiment of a haptic device 100 with a piezoelectric actuator 1 with amplification elements 30 in a perspective view and in a sectional view. The geometries of the actuator shown in the Fig. 1A and Fig. The piezoelectric actuator 1 and the amplification elements 30 shown in Figure 1B are purely exemplary and are intended to illustrate the operating principle and interaction of the piezoelectric actuator 1 with the amplification elements 30. Deviations from the illustrated embodiment, for example with regard to geometric configurations, are not excluded by the following description. Furthermore, in the illustrated embodiment, as well as in the embodiments described below, there may, for example, be only one amplification element 30.

[0049] The piezoelectric actuator 1 has a base body 10 with a first main surface 11 and a second main surface 12, on each of which one of the reinforcing elements 30 is arranged. The base body 10 has a stack of inner electrodes 13 and piezoelectric layers 14 arranged alternately in a stacking direction S, which are electrically contacted by the inner electrodes 13. The inner electrodes 13 can be electrically contacted from the outside via outer electrodes 15 on a surface of the base body 10. Even if in Fig. Figure 1B shows a plurality of internal electrodes 13; however, the base body 10 can also have, for example, only one or two or another number of internal electrodes 13. Furthermore, the base body 10 can also be free of internal electrodes, so that the base body 10 can be designed as a monolithic disk or plate free of internal electrodes. In this case, electrical contact is made exclusively via the external electrodes 15.

[0050] The base body 10 is preferably cuboid in shape with an elongated form, as shown, and has a longitudinal direction of length L, which corresponds to the principal extension direction of the base body 10. Perpendicular to the longitudinal direction, the base body 10 has a lateral direction of width B. Perpendicular to the longitudinal direction, the base body 10 terminates with end faces 16. Along the lateral direction, the base body 10 terminates with longitudinal side faces 17, which are oriented perpendicular to the lateral direction. The end faces 16 and the longitudinal side faces 17 form the side faces of the base body 10. In the vertical direction, which is perpendicular to both the longitudinal and lateral directions, the base body 10 has a height H and terminates with a top surface 18, which forms the first main surface 11, and a bottom surface 19, which forms the second main surface 12, both of which are perpendicular to the vertical direction.The height direction preferably corresponds to the stacking direction S. As an alternative to the cuboid shape shown, the base body 10 can also have other shapes, wherein preferably at least the top 18 and the bottom 19 are parallel to each other.

[0051] A first reinforcement element 30 is arranged on the first main surface 11 of the base body 10, and thus of the piezoelectric actuator 1, and the second reinforcement element 30 is arranged on the second main surface 12 of the base body 10, and thus of the piezoelectric actuator 1, opposite the first main surface 11 along the stacking direction S. Although two reinforcement elements 30 are always shown here and in the following, it is also possible that, for example, only the first reinforcement element 30 is present on the first main surface 11. The reinforcement elements 30 have fastening areas 39 by which the reinforcement elements 30 are attached to the respective main surfaces 11 and 12.

[0052] As described above, the piezoelectric actuator 1 also has two external electrodes 15, which are provided for external electrical contact with the base body 10 and thus with the piezoelectric actuator 1. The external electrodes 15 are, as shown in Fig. As shown in Figure 1A, the outer electrodes 15 are preferably applied to one of the longitudinal side surfaces 17 of the base body 10. The inner electrodes 13 are alternately contacted with one of the outer electrodes 15 in the stacking direction S. The outer electrodes 15 are applied in the form of one or more metal layers, preferably by sputtering, screen printing, dip coating, or another suitable method. By arranging the outer electrodes 15 side by side on the same longitudinal side surface 17, this can preferably be done in a single process step.

[0053] The piezoelectric layers 14 can, for example, be lead zirconate titanate ceramics (PZT ceramics). The PZT ceramic can furthermore contain Nd and Ni. Alternatively, the PZT ceramic can also contain Nd, K, and optionally Cu. Alternatively, the piezoelectric layers 14 can be a Pb (Zr) x Ti 1-x ) O3 + y Pb (Mn 1 / 3 Note 2 / 3 The electrodes must have a composition containing O3. Alternatively, a piezoelectric polymer, for example, can be used instead of a piezoelectric ceramic material. The inner electrodes 13 and the outer electrodes 15 preferably have copper or consist of copper or a copper alloy.

[0054] The base body 10, and thus the piezoelectric actuator 1, can, for example, have a length L greater than or equal to 5 mm and less than or equal to 100 mm, and a width B greater than or equal to 2 mm and less than or equal to 8 mm. The height H of the piezoelectric actuator 10 can, for example, be greater than or equal to 300 µm and less than or equal to 3 mm.

[0055] The piezoelectric actuator 1 is designed such that when an electrical voltage is applied to the outer electrodes 15 and thus also to the inner electrodes 13, a deformation of the base body 10 takes place, in particular in the multi-layer construction shown with the inner electrodes 13 a change in length in the Fig. 1B indicates the direction of length change R1. In particular, the piezoelectric layers 14 are polarized such that applying an electrical voltage between the inner electrodes 13 leads to a contraction of the base body 10, whereby the length L of the base body 10 changes perpendicular to the stacking direction S. Consequently, the base body 10, and thus the piezoelectric actuator 1, expands transversely to the polarization direction and the electric field, which is also known as the d31 effect. Other expansion changes can be achieved through other configurations with or without inner electrodes in the base body 10. For the sake of clarity, the following description refers, without being limiting, to the multilayer design shown with the described length change.

[0056] To redirect the effect of the length change in the stacking direction S, the reinforcing elements 30 are provided. When a voltage is applied to the piezoelectric actuator 1, the reinforcing elements 30 deform at least partially as a result of the change in the extension of the base body 10. In particular, the reinforcing elements 30 are dimensioned and connected to the base body 10 of the piezoelectric actuator 1 such that each stroke area 31 of the reinforcing elements 30, as a result of a change in the length L of the base body 10, exhibits a stroke movement in the direction corresponding to the stacking direction S. Fig. 1B performs the indicated stroke direction R2, wherein the amplitude of the stroke movement may preferably be larger than the amplitude of the change in length L of the piezoelectric actuator 1.

[0057] The piezoelectric actuator 1 is preferably arranged between the reinforcing elements 30, as shown. Each of the reinforcing elements 30 is preferably a single piece and, in the illustrated embodiment, is strip-shaped with a rectangular base. Furthermore, each of the reinforcing elements 30 is curved or bent and is U-shaped. Alternatively, the reinforcing elements 30 can also be planar. For example, the reinforcing elements 30 each comprise a sheet metal strip or are made of it, in particular of steel and / or titanium.

[0058] Each of the reinforcing elements 30 is preferably subdivided into several areas or sections. In addition to the stroke area 31, each reinforcing element 30 has edge areas 32 that are connected to the respective stroke area 31 via transition areas 33. The two edge areas 32 of each of the reinforcing elements 30 rest on one of the main surfaces 11, 12 of the base body 10. The edge areas 32 are preferably permanently connected to the respective main surface 11, 12, so that in the illustrated embodiment, the edge areas 32 of the reinforcing elements 30 are the fastening areas 39 of the reinforcing elements 30. In particular, each of the fastening areas 39 is connected to the respective main surface 11, 12 by a bonding layer 20, which is Fig. 1B is indicated. Even if in Fig. In Figure 1A and in the following described figures the connecting layers 20 are not shown, a connecting layer is always arranged between a mounting area 39 and the piezoelectric actuator 1.

[0059] The bonding layer 20 can particularly preferably be formed by an adhesive, for example an epoxy, so that the reinforcing elements 30 are preferably connected to the base body 10 and thus to the piezoelectric actuator by adhesive bonds. A solder layer, microsilver, or a weld layer are also possible for the bonding layers 20.

[0060] The stroke areas 31 are spaced apart from the respective main surfaces 11, 12. In particular, a clearance area 38 is located between the stroke area 31 of each of the reinforcement elements 30 and the respective main surface 11. The clearance areas 38 have a height that is, for example, greater than or equal to 0.1 mm and less than or equal to 5.0 mm when no voltage is applied to the piezoelectric actuator 1 and no external force acts on the reinforcement elements 30.

[0061] Preferably, the lifting areas 31 are designed such that they run essentially parallel to the main surfaces 11, 12. The transition areas 33 run obliquely to the main surfaces 11, 12. In other words, each of the transition areas 33 forms an angle with the main surfaces 11, 12. The angle is preferably less than or equal to 45°. This reduces the height of the clearance area 38 in the direction from the lifting area 31 towards the edge areas 32 and thus towards the fastening areas 39 of the respective reinforcement element 30.

[0062] If an electrical voltage is applied to the piezoelectric actuator 1, for example by a control device connected to the outer electrodes 15 of the piezoelectric actuator 1, the stroke areas 31 of the reinforcement elements 30 move relative to the base body 10 in the stroke direction R2, as described above. This movement can be perceived as a haptic signal, for example by a user. The reinforcement elements 30 preferentially bend at the transitions between the stroke areas 31 and the transition areas 33, as well as between the transition areas 33 and the edge areas 32. Movement of the edge areas 32 in the stroke direction R2 is prevented by their attachment to the piezoelectric actuator 1 via the connecting layers 20. Instead, the edge areas 32 move with the base body 10 in the longitudinal direction R1. Thus, a relative movement occurs between the edge areas 32 and the stroke areas 31.

[0063] When a force is applied to the piezoelectric actuator 1 along the stroke movement R2, for example, by a user's haptic input, the reinforcement elements 30 are deformed such that the stroke areas 31 are pressed closer to the respective main surfaces 11, 12, and the edge areas 32 are pushed away from each other in the longitudinal direction R1. Because the reinforcement elements 30 are attached to the base body 10 of the piezoelectric actuator 1, this body is also deformed in the longitudinal direction R1. This generates an electrical voltage in the piezoelectric actuator 1. This voltage can be detected at the external electrodes 15, thus indicating haptic input. The piezoelectric actuator 1 can therefore be used as a sensor that can detect a force applied by a user.For this purpose, the piezoelectric actuator 1 can be connected to a control unit at the external electrodes 15, which evaluates the electrical voltages generated at the piezoelectric actuator 1.

[0064] Modifications and further developments of the haptic device 100 according to the previous embodiment are shown in conjunction with the figures described below. Therefore, the following description is essentially limited to differences from the previous embodiments. For the sake of clarity, it is possible that not all elements and components are shown in the figures described below, or that they are shown but not labeled or explained. Elements and components not shown or labeled in a figure may, for example, be designed according to the description of the respective preceding or subsequent embodiments.

[0065] As in Fig. As shown in Figure 2A in a further embodiment of a haptic device 100 with the piezoelectric actuator 1 and the reinforcing elements 30, the reinforcing elements 30 can have thinnings 34 between the aforementioned areas, which allow for improved deformability of the reinforcing elements 30 and facilitate the execution of the previously described stroke movement. Furthermore, openings 35 can be present in the stroke area 31 of the reinforcing elements 30, which, for example, allow for mechanical connection of the reinforcing elements 30 to other components, for example, by means of rivets or screws. As shown in the following figures, the stroke area 31 can also, for example, have or be connected to connecting plates by means of which the haptic device 100 can be mounted to other components.

[0066] In Fig. Figure 2B shows a further embodiment of the haptic device 100, which has a flexible connection element 40, for example a so-called flexible printed circuit board (FPC), which is connected to the two connection electrodes. For example, the connection element 40 can be soldered to the outer electrodes on the longitudinal side surface.

[0067] By electrically connecting the piezoelectric actuator 1 via the terminal element 40 on its longitudinal side surface, a reduction in process steps can be achieved, for example, in the production of the external contacts on the base body. Typically, the external electrodes of elongated piezoceramic components are located on the two end faces of the base body. Such positioning of electrical contacts leads to increased complexity in mass production and limits the possibilities for electrical connections. For example, FPC connections then become very difficult or even impossible to implement. By placing the external electrodes side by side on a single longitudinal side surface of the piezoelectric actuator 1, the production effort can be essentially halved, since both external electrodes can be applied in a single process step.Furthermore, the piezoelectric actuator 1 can be connected via a connection element 40 formed by an FPC, as described. This reduces the overall space requirement for the system integration of the haptic device 100 and simplifies handling. Particularly in high-volume production, this can also reduce production costs, as the connection process for attaching the connection element 40 takes place on only one side of the piezoelectric actuator 1. Moreover, processes such as reflow soldering, laser soldering, hotbar soldering, or the use of anisotropic conductive film (ACF) are only feasible with the described geometry.

[0068] As described above, the reinforcing elements 30 are attached to the piezoelectric actuator 1 via the bonding layers 20 and their respective mounting areas 39. With this type of construction, there is a risk of delamination of the reinforcing elements 30 if the haptic device is operated under harsh conditions, i.e., at elevated temperatures and / or in an atmosphere with high humidity and / or other damaging substances. During operation, the deformations of the piezoelectric actuator 1 and the reinforcing elements 30, as described above, exert shear forces on the bonding layers 20, which, as described, may contain or be composed of an adhesive. Most commercially available adhesives have reduced shear strength under harsh conditions, especially at elevated temperatures.If the applied shear force exceeds the shear strength of the adhesive, the bonded layers can detach over time. Typically, an initial crack forms at the edge of the bonded layer, which propagates until the affected bonded area is completely delaminated.

[0069] As simulations have shown, delamination is primarily promoted by two factors. The first factor is the shrinkage and expansion of the ceramic material of the base body, which can occur during operation below a bonding area 39. The second factor is a force acting perpendicular to the bonding layer 20 during operation as a result of the reinforcing movement of a reinforcing element 30. The simulations have shown that, during operation, the expected shear stress on a bonding layer, promoted by both factors, can be equal to or greater than the shear strength of most adhesives on the market. Furthermore, the shear strength of adhesives is temperature-dependent, so an increase in temperature can lead to a decrease in shear strength.For most adhesives, the shear strength at elevated temperatures is lower than the shear stress typically encountered during operation, as determined by simulations. Prolonged operation can lead to cracking of the bonding layer at the interface with the bonding area of ​​a reinforcing element. Once such a crack has formed, each subsequent operation promotes crack propagation along the contact surface between the bonding layer and the reinforcing element until the corresponding bonding area is delaminated. Crack propagation is primarily caused by the second factor described above.

[0070] To improve the reliability of the attachment of the reinforcement elements 30 to the mounting areas 39 on the piezoelectric actuator 1, the haptic device 1 further comprises at least one fastening improvement element. The embodiments of the at least one fastening improvement element described below can also be provided in the preceding embodiments. Furthermore, the embodiments of the at least one fastening improvement element can also be combined, so that a plurality of the described fastening improvement elements can be provided in the haptic device 100.

[0071] In particular, the at least one fastening improvement element 50 can be part of a reinforcement element 30 or of both reinforcement elements 30. In particular, the at least one fastening improvement element 50 can have or be a structure in or on at least one reinforcement element that is designed and configured, for example, to counteract the previously described detachment effect promoted by shear forces.

[0072] In Fig. Figure 3A shows an embodiment of a haptic device 100 with fastening improvement elements 50. Fig. Figure 3B shows the two reinforcing elements 30 of the haptic device 100 and in Fig. 3C is only one of the reinforcement elements 30 shown.

[0073] The reinforcement elements 30 each have a fastening improvement element 50 in each mounting area 39. The fastening improvement elements 50 are each formed on a mounting surface 390 of each of the mounting areas 39 facing the base body and thus the piezoelectric actuator 1, and are formed by a surface structure in which a portion of the bonding layer is arranged. In the illustrated embodiment, the respective surface structure has at least one recess 51 or is designed as such. The respective recess 51, which can, for example, form a pocket in the shape of a wedge-shaped depression in the mounting surface 390, allows for a local increase in the amount of bonding layer material and thus a locally greater bonding layer thickness.The recesses 51 are particularly preferably formed on an edge of the edge regions 32, which are designed as fastening areas 39, facing the lifting area 31. A particularly high tendency to detach can be present on the edge of an edge region 32 facing the lifting area 31, which can be counteracted by the locally greater thickness of the bonding layer.

[0074] Furthermore, in the described and following embodiments, the thickness of the bonding layers 20 can be increased by applying prepregs 21 in order to define the thickness precisely, as in Fig. As indicated in section 4, a prepreg 21 can, as described in the general section, be a basic element of a printed circuit board and comprise a glass fiber fabric impregnated with an epoxy adhesive. A specific thickness of the bonding layers 20 can be achieved by using multiple layers of fabric, which are then filled with an adhesive 22.

[0075] In the Fig. 5A to 5C is in views that correspond to the views of the Fig. As illustrated in Figures 4A to 4C, a further embodiment is shown in which the fastening improvement elements 50 have a surface-enhancing structure 52 in which at least part of the bonding layer is arranged. The surface-enhancing structure 52 is formed in the form of grooves or slots, such as longitudinal grooves or, as shown, transverse grooves. The respective surface-enhancing structure 52 increases the interface between the fastening surfaces 390 and the respective bonding layer, thereby increasing the fastening effect of the bonding layers.

[0076] The fastening improvement elements 50, described as surface structures in the fastening surfaces 390, can provide measures to reduce the occurrence of cracks, in particular by increasing the thickness of the bonding layer at the inner edge of the fastening areas 39, i.e., the edge facing the respective stroke region 31. By increasing the thickness of the bonding layers in these areas, the acting shear load can be distributed over a larger volume of the bonding layer material, thus reducing the maximum shear load in the fastening areas 39. In both illustrated embodiments, the fastening areas 39 are therefore each divided into two areas: an outer area facing away from the respective stroke region 31 and an inner area facing the respective stroke region 31. According to the embodiment of Fig. In 3A to 3C, the respective outer region has a thinner part of the bonding layer, which strengthens the overall connection between the reinforcing element 30 and the piezoelectric actuator 1, while the respective inner region contains a thicker part of the bonding layer to distribute the shear stress. According to the exemplary embodiment of Fig. In sections 5A to 5C, the respective inner area is preferably reduced to half the sheet thickness, and grooves or slots are preferably formed perpendicular to the longitudinal direction of the haptic device 100. This increases the thickness of the bonding layer and the area of ​​the respective fastening area 39 that interacts with the bonding layer.

[0077] In the Fig. 6A to 6C is in views that correspond to the views of the Fig. As shown in Figures 4A to 4C, a further embodiment is shown in which the fastening improvement elements 50 each have at least one wing element 53 adjacent to the fastening areas 39, each of the wing elements 53 extending at least partially along a side surface of the piezoelectric actuator 1 adjacent to the main surfaces, in the illustrated embodiment a longitudinal side surface. The wing elements 53 are formed integrally with the respective fastening area 39 and each form a kind of tab or clamp that covers or encloses a part of the side surface.

[0078] The bonding layer is preferably arranged for each of the fastening improvement elements 50, designed as wing elements 53, not only between the mounting surface 390 and the corresponding main surface of the piezoelectric actuator 1, but also additionally between the wing element 53 and the piezoelectric actuator 1. This allows the wing elements 53 to increase the contact area between the reinforcement elements 30 and the piezoelectric actuator 1. Furthermore, by arranging a wing element 53 on a side surface of the base body of the piezoelectric actuator 1, support and a different force distribution compared to the mounting area 39 can be achieved, thereby counteracting detachment effects.Furthermore, the respective connecting layer can additionally be arranged between a wing element 53 of one of the reinforcement elements 30 and the fastening area 39 and / or the wing element 53 of the other reinforcement element 30, so that the two reinforcement elements 30 are attached to each other by the connecting layer between the respective wing elements 53 and / or fastening areas 39.

[0079] In the Fig. 7A to 7C is in views that correspond to the views of the Fig. 4A to 4C, a further embodiment is shown in which the fastening improvement elements 50, designed as wing elements 53, further comprise a toothed structure 54 which is designed and configured to engage in a complementary toothed structure 54 of a wing element 53 or of a fastening area 39 of the respective other reinforcement element 30. Fig. Figure 7D shows a section of the haptic device 100. Fig. Figure 7E shows a longitudinal view of the haptic device 100. The bonding layer is preferably additionally arranged between the toothed structures 54 of the two reinforcing elements 30.

[0080] Furthermore, in the illustrated embodiment, the reinforcement elements 30 at the stroke regions 31 have, purely by way of example, connecting plates 31' for mounting the haptic device 100. The connecting plates 31' extend along the width direction away from the piezoelectric actuator 1 and from the respective stroke region 31, thus forming an angle of 90° or substantially 90° with the longitudinal side surfaces of the piezoelectric actuator 1 and the stroke regions 31. At the transition between the stroke regions 31, which run parallel to the longitudinal side surfaces, and the connecting plates 31', the reinforcement elements 30 each have a reinforcement section 31'' bent by an angle of 180° or substantially 180°. By bending by 180° or substantially 180°, it is possible to transfer the force of the stroke movement centrally to the mounting areas 39, as shown in the Fig. 7E can be seen, which prevents or at least reduces twisting and torsion of the reinforcement elements 30. In combination with connecting elements 37 between the stroke areas 31 and the reinforcement areas 31'', such as weld points or adhesive points, as shown in Fig. 7F is indicated, or a weld or adhesive seam, as in Fig. As indicated in 7G, it may be possible to increase the stiffness of the reinforcement elements 30 in order to transfer energy with minimal losses. This can lead to enhanced haptic feedback. The embodiments described below may also include connecting plates or connecting plates and reinforcement areas, which, for the sake of clarity, are not labeled with reference numerals.

[0081] In the Fig. 8A and Fig. 8B shows a further embodiment in which, in comparison to the embodiment of the Fig. 7A to 7D, the reinforcing elements 30 project longitudinally beyond the piezoelectric actuator 1. The representation of the Fig. Figure 8A shows the haptic device 100 according to the illustration of the Fig. 7A, while in Fig. Figure 8B shows the piezoelectric actuator 1 with only one of the connecting elements 30. Because the reinforcing elements 30 project longitudinally beyond the piezoelectric actuator 1, protection can be achieved for the edges in the area of ​​the end faces 16. In contrast to the previous variant, the projecting areas do not form a positive-locking clamp with the piezoelectric actuator 1, but rather create a longitudinal overhang. This overhang can be used as strain relief for any electrical connections, such as the flexible connecting element described above. The enclosed areas can be filled with the material of the connecting layers, so that the end faces 16 of the piezoelectric actuator 1 can be covered with the material of the connecting layers and protected against accidental operation.

[0082] In the Fig. 9A to 9C is in views that correspond to the views of the Fig. 4A to 4C, a further embodiment is shown in which each of the fastening areas 39 of the reinforcement elements 30 has as fastening improvement elements 50 two wing elements 53 with toothed structures 54 which extend at least partially along two opposite longitudinal side surfaces of the piezoelectric actuator 1.

[0083] In the Fig. 10A to 10C is in views that correspond to the views of the Fig. 4A to 4C correspond to a further embodiment shown in which the fastening improvement elements 50 designed as wing elements 53 extend partially over the end faces of the piezoelectric actuator 1 compared to the previous embodiments.

[0084] The ones associated with the Fig. The wing elements 53 described in Sections 6A to 11C have, among other things, the functionality of clamps that partially encircle the piezoelectric actuator 1 and which can preferably form an interlocking clamp-like structure by means of toothed structures 54 on each side of the mounting areas 39. In particular, the mounting areas 39 can form closed structures with the wing elements 53 that are filled or even encased with the material of the connecting layers. In a preferred embodiment, as described in the Fig. As shown in Figures 7A to 9C, the wing elements 53 with the toothed structures 54 are formed in a mirror image of each other. When the haptic device 100 is fully assembled, the mounting areas 39 with the wing elements 53 completely enclose the piezoelectric actuator 1 in the mounting areas 39.

[0085] In the Fig. Figures 11A to 11C, 12A to 12C, and 13 show further embodiments of the haptic device 100, which include fastening improvement elements 50 in the form of clamping devices 55. These clamping devices are present in addition to the reinforcing elements 30, in contrast to the previous embodiments. The views of Fig. 11A and Fig. 12A and the Fig. 11B and Fig. 12B each correspond to the view of Fig. 4A or the view of Fig. 4B, while in the Fig. 11C and Fig. Figure 12C shows a clamping device 55 in each case. The clamping devices 55 are slid onto the reinforcing elements 30 and the piezoelectric actuator 1 in the mounting areas 39 of the reinforcing elements 30. The clamping devices 55 are particularly preferably ring-shaped, as shown in the Fig. shown in 11A to 11C, or cap-shaped, as in the Fig. Figures 12A to 12C show that the clamping devices can preferably be designed as ring elements or as cap elements.

[0086] To prevent the growth of cracks in the bonding layers, forces acting perpendicular to the bonding layers can be counteracted by using the clamping devices 55. The clamping devices 55 clamp the mounting areas 39, thus preventing movement of the mounting areas 39 perpendicular to the main surfaces of the piezoelectric actuator 1. Additionally, a separate adhesive or the material of the bonding layers can be applied to fix the position of the clamping devices 55 on the mounting areas 39. This also compensates for any tolerances of the reinforcing elements 30, ensuring reliable clamping during operation.

[0087] Alternatively or additionally, the clamping devices 55 can be conically shaped, as in Fig. 13 in a sectional view of part of the haptic device 100 is indicated by a clamping device 55 designed as a cap element, wherein in this embodiment the reinforcing elements 30 additionally have recesses 51 for the connecting layers 20 as fastening improvement elements 50, as in connection with the Fig. As described in sections 4A to 4C. Due to its shape, the clamping device 55 can be fixed by frictional forces. However, applying an additional filler adhesive to the clamping device 55 can be used as an additional safety measure to improve reliability.

[0088] In Fig. 14, which is in the view of Fig. As shown in Figure 1B, a further embodiment of the haptic device 100 is shown, in which the fastening improvement element 50 has passive areas 56 in the piezoelectric actuator 1, i.e., areas that do not participate in length changes of the piezoelectric actuator 1. As described above, one of the main causes of the shear stress in the fastening areas 39 with the bonding layers 20 is the shrinkage and expansion of the area of ​​the piezoelectric actuator 1 beneath the fastening areas 39. Therefore, in the illustrated embodiment, the passive areas 56 are arranged in the area of ​​the fastening areas 39 and preferably border the fastening areas 39. As shown in Fig. As shown in Figure 14, the passive regions 56 are those regions of the base body 10 that are free of any internal electrodes 13. Therefore, the regions of the main surfaces 11, 12 that are in contact with the connecting layers 20 are passive surfaces that do not undergo any change in length.

[0089] Simulations have shown that this significantly reduces the shear stress on the fastening areas 39 during operation. In particular, it has been shown that the shear stress falls below the shear strength of most adhesives available on the market, which is true for at least some adhesives even at elevated temperatures, thus increasing the selection of possible materials for the bonding layer 20. The fastening improvement elements 50, designed as passive areas 56, can be particularly preferably combined with the clamping devices 55 according to the exemplary embodiments of the Fig. 11A to 13 can be combined.

[0090] In Fig. Figure 15 shows a section of a further embodiment of the haptic device 100, which has a conformal coating 57 as a fastening improvement element 50. The conformal coating 57 covers at least the bonding layers 20 and the fastening areas 39, and particularly preferably the entire haptic device 100. The conformal coating 57 covers the surfaces of the haptic device 100 with a substantially uniform, thin layer and comprises or is made of a plastic material, for example, based on a silicone or acrylate.The conformal coating 57, which preferably covers all free surface areas or at least all free surface areas except for the outer electrodes, protects the bonding layers 20 from damaging external influences such as moisture, which could lead to degradation of the bonding layers 20 and thus to a deterioration of the adhesion of the reinforcing elements 30. In particular, at high humidity of, for example, 85% RH or more and high temperatures of, for example, 85°C or more, the adhesion properties of the bonding layers 20 can degrade further during operation of the haptic device 100, which can significantly reduce its service life. The conformal coating 57, acting as an adhesion improvement element 50, counteracts this effect.

[0091] To produce the conformal coating 57, the base body 10 of the piezoelectric actuator 1 can first be manufactured such that all edges are rounded. Rounding the edges improves their coverage with coating materials. Generally, the problem of poor edge coverage during coating is due to a high surface tension of the component to be coated and an unsuitable viscosity of the coating material. Therefore, the viscosity of the coating material for the conformal coating 57 is further adjusted to achieve optimal coverage of the entire surface. This ensures that the rounded edges of the base body 10 are encased by the coating material in the subsequent step, preventing the formation of diffusion pathways for moisture to and into the bonding layers 20.A closed coating 57 is therefore particularly advantageous for ensuring the reliable function of the haptic device 100. In a further step, the piezoelectric actuator 1 with the attached reinforcing elements 30 is coated with the coating material to form the conformal coating 57. This can be done, for example, by methods such as spray coating, brush application, and dip coating.

[0092] The haptic device 100 is not limited to the geometries of the previously described embodiments. The haptic device 100 can, for example, also be designed according to one of the geometries described in the Fig. The designs shown in sections 16A to 18C may be implemented. In particular, the designs shown in the Fig. The embodiments shown in 16A to 18C include at least one or more fastening improvement elements according to one or more of the preceding embodiments.

[0093] As in the Fig. 16A and Fig. As shown in Figure 16B in a three-dimensional view and in a sectional view, the reinforcing elements 30 can be flush with the end faces 16 of the piezoelectric actuator 1 along the longitudinal direction or even project beyond the end faces 16. This protects the piezoelectric actuator 1 against impacts and shocks at the end faces 16.

[0094] In the Fig. 17A to 17C is in views that correspond to the views of the Fig. As illustrated in Figures 4A to 4C, a further embodiment is shown in which the reinforcement elements 30 each have several stroke ranges 31 and thus several haptically active areas, between which an intermediate area 36 is provided, which, in addition to the edge areas 32, forms a mounting area 39 of the respective reinforcement element 30. The features described for the mounting areas 39 formed by edge areas 32 according to the previous embodiments also apply to the intermediate areas 36. Particularly preferably, the piezoelectric actuator 1 can also have a passive area as a mounting enhancement element in the area of ​​the outer electrodes 15, which is adjacent to the intermediate areas 36 of the reinforcement elements 30.

[0095] Furthermore, as in the Fig. 18A to 18C in views corresponding to the views of Fig.4A to 4C, as shown, the stroke area 31 of the reinforcement elements 30, for example, can also directly border an edge area 32 without a transition area being present between the stroke area 31 and the relevant edge area 32.

[0096] The invention is not limited to the description provided by means of the exemplary embodiments. Rather, the invention encompasses every new feature as well as every combination of features, which in particular includes every combination of features in the claims, even if that feature or combination itself is not explicitly stated in the claims or exemplary embodiments. Reference symbol list 1 piezoelectric actuator 10 basic shapes 11, 12 Main surface 13 Internal electrode 14 piezoelectric layer 15 External electrode 16 Front surface 17 Longitudinal side surface 18 Top 19 Subpage 20 Compound layer 21 Prepreg 22 Adhesive 30 Reinforcing element 31 lifting range 31' Connecting plate 31'' amplification range 32 Edge area 33 Transition area 34 Thinning 35 Opening 36 Intermediate area 37 Connecting element 38 outdoor area 39 Mounting area 390 mounting surface 40 connection element 50 fastening improvement element 51 In-depth study 52 surface-enlarging structure 53 wing element 54 Gear structure 55 Clamping device 56 passive area 57 Coating 100 haptic devices B Width H height Length L R1 Length change direction R2 lifting direction S Stacking direction QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2017 / 032 868 A1

[0003] WO 2018 / 046 201 A1

[0003] WO 2020 / 011 403 A1

[0003] WO 2021 / 019 083 A1

[0003]

Claims

[1] Haptic device (100) comprising - comprising a piezoelectric actuator (1) and a base body (10) and - at least one amplification element (30) on a first main surface (11) of the piezoelectric actuator (1), wherein the at least one reinforcing element (30) has at least one fastening area (39) with which the at least one reinforcing element (30) is attached to the base body (10) and a lifting area (31) which is spaced apart above the first main surface (11), wherein a connecting layer (20) is arranged between the at least one fastening area (39) and the first main surface (11). [2] Haptic device (100) according to claim 1, wherein the at least one fastening area (39) of the at least one reinforcing element (30) is an edge area (32) or an intermediate area (36) of the at least one reinforcing element (30). [3] Haptic device (100) according to claim 1 or 2, wherein the haptic device (100) has at least one fastening improvement element (50) which is designed to increase the reliability of the fastening of the at least one fastening area (39) to the base body (10). [4] Haptic device (100) according to claim 3, wherein the at least one fastening improvement element (50) is part of the at least one reinforcement element (30). [5] Haptic device (100) according to claim 4, wherein the at least one fastening improvement element (50) has a recess (51) on a fastening surface (390) facing the piezoelectric actuator (1) of the at least one fastening area (39), in which at least a part of the connecting layer (20) is arranged. [6] Haptic device (100) according to claim 5, wherein the recess (51) is formed on an edge of the at least one fastening area (39) facing the lifting area (31). [7] Haptic device (100) according to one of claims 4 to 6, wherein the at least one fastening improvement element (50) has a surface-enlarging structure (52), in particular grooves, on a fastening surface (390) facing the piezoelectric actuator (1), in which at least a part of the connecting layer (20) is arranged. [8] Haptic device (100) according to one of claims 4 to 7, wherein the at least one fastening improvement element (50) has at least one wing element (53) adjacent to the fastening area (39) which extends at least partially along a side surface (16, 17) of the base body (10) adjacent to the first main surface (11). [9] Haptic device (100) according to claim 8, wherein the at least one fastening improvement element (50) has two wing elements (53) which extend at least partially along two opposite longitudinal side surfaces (17) of the base body (10). [10] Haptic device (100) according to claim 8 or 9, wherein the at least one wing element (53) is attached to the base body (10) and / or to a further reinforcing element (30) with a part of the connecting layer (20). [11] Haptic device (100) according to one of claims 8 to 10, wherein the at least one wing element (53) has a toothing structure (54) which is configured to engage in a complementary toothing structure (54) of a further reinforcing element (30). [12] Haptic device (100) according to one of claims 3 to 11, wherein the at least one fastening improvement element (50) has a prepreg (21) between the first main surface (11) and the fastening area (39) of the at least one reinforcement element (30). [13] Haptic device (100) according to one of claims 3 to 12, wherein the at least one fastening improvement element (50) has a clamping device (55) which is pushed onto the at least one reinforcing element (30) and the base body (10) in the fastening area (39) of the at least one reinforcing element (30). [14] Haptic device (100) according to one of claims 3 to 13, wherein the at least one fastening improvement element (50) has at least one passive area (57) in the piezoelectric actuator (1) adjacent to the at least one fastening area (39). [15] Haptic device (100) according to any one of claims 3 to 14, wherein the at least one fastening improvement element (50) has a conformal coating (57) that envelops the haptic device (100). [16] Haptic device (100) according to one of the preceding claims, wherein the at least one reinforcing element (30) projects beyond the base body (10) on a side facing away from the stroke area (31). [17] Haptic device (100) according to one of the preceding claims, wherein the fastening area (39) is enveloped with the bonding layer (20). [18] Haptic device (100) according to one of the preceding claims, wherein the piezoelectric actuator (1) has a longitudinal side surface (17) on which two external electrodes (15) are arranged for electrical contacting the haptic device (100). [19] Haptic device (100) according to claim 18, wherein a flexible connecting element (40) is connected to the two external electrodes (15). [20] Haptic device (100) according to claim 15 and claim 19, wherein a part of the flexible connecting element (40) together with the piezoelectric actuator (1) and the at least one reinforcing element (30) is enveloped by the conformal coating (57).

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