CONTROL ELEMENT WITH IMPROVED HAPTIC FEEDBACK LIMITED TO THE ACTUATING SURFACE

Description

[0001] The invention relates to an operating element with an actuating part which has an actuating surface for carrying out an operating input by an operator. A detection means is assigned to the actuating part in order to detect a touch or an actuation of the actuating part which goes beyond a touch. Actuation is understood to be a displacement of the actuating part under the influence of an actuating force applied by an operator and acting on the actuating surface. For this purpose, the actuating part is usually mounted on a support in an elastically oscillating manner in order to enable a displacement for the actuation but also to excite vibration of the actuating part. In order to create a forced vibration or at least a deflection, a so-called active haptic feedback, for haptic confirmation orTo acknowledge a previous touch or actuation, an actuator that can be actuated with an electrical control signal is provided. In general, there is the problem that the vibration excitation generated is not limited to the actuation surface and spreads further, for example as structure-borne sound, through the actuating part. This has several disadvantages. On the one hand, there is a desire to limit the haptic feedback to the actuation surface in order to create a clear assignment for the operator to the respective actuation surface. This is particularly advantageous for extensive surfaces where the actuation surface only makes up a fraction of the surface or where multiple actuation surfaces are provided and limiting the haptic feedback to the respective area helps the operator with haptic orientation on the surface.In addition, there is the problem that the undamped propagating structure-borne sound can contribute to the generation of unwanted noise, for example in the fastening structure outside the control element, but the secondary sound generated by the structure-borne sound can also be problematic.

[0002] Against this background, there was a need for a solution for an operating element with an oscillating actuating part for generating active haptic feedback, in which the active haptic feedback is limited to the actuating surface and the operating element can be implemented in a structurally simple and lightweight manner. This object is achieved by an operating element according to claim 1. An equally advantageous use is the subject of the independent claim. Advantageous embodiments are each the subject of the dependent claims. It should be noted that the features individually listed in the claims can be combined with one another in any technologically expedient manner and demonstrate further embodiments of the invention. The description, particularly in conjunction with the figures, further characterizes and specifies the invention.

[0003] The invention relates to an operating element. The term "operating element" is to be interpreted broadly and serves to perform an operating input using a movable actuating part within the framework of a human-machine interface.

[0004] The control element according to the invention has a support. The term "support" is to be interpreted broadly and refers, for example, to a component that serves to secure the control element to a supporting structure or, for example, is directly or indirectly attached to a motor vehicle component. For example, the support is designed as a housing. For example, the support is not visible to the operator when the control element is properly attached. The support is made, for example, of a plastic, a metal, or a metallic alloy, such as ZAMAK, or combinations thereof.

[0005] The operating element according to the invention further comprises an actuating part supported on the support, which forms a visible surface facing an operator and which forms at least one island-shaped actuating surface within the visible surface. The actuating surface is formed by a self-supporting actuating section of the actuating part; and the actuating section is surrounded by an insulating section of the actuating part that is more flexible than the actuating section, so that the actuating section is mounted relative to the support in a manner capable of oscillation, particularly in the direction perpendicular to the actuating surface. An "island-shaped" arrangement of the actuating surface within the visible surface is also understood to mean an arrangement in which an edge of the actuating surface partially coincides with an outer boundary of the visible surface; i.e., the "island-shaped" arrangement does not necessarily require placement entirely within the visible surface.However, it is preferably provided that the actuating surface is arranged at a distance from the outer boundary of the visible surface.

[0006] According to the invention, the operating element has detection means for detecting contact with the actuating surface and / or for detecting actuation of the actuating part. For example, a capacitive touch sensor is provided for detecting contact, or a resistive, capacitive, inductive, or optical force sensor is provided for detecting actuation of the actuating part. The force sensor is preferably a contactless force sensor, i.e., the self-supporting actuating surface is not supported on the support part via the force sensor.

[0007] According to the invention, an actuator is further provided on the actuating section, from the operator's perspective, below the actuating section or on the side thereof facing away from the operator. In the event of positive detection of an actuation or contact, the actuator is supplied with an electrical excitation signal by the detection means to excite a vibration of the actuating section for haptic feedback. The actuator is an active actuator, i.e., an actuator that can be triggered by an electrical excitation signal provided by the detection means. By applying a pulse, such as an impact or vibration, to the actuating section of the actuating part, it is capable of exciting a deflection or vibration therein, which is haptically perceptible to the operator via the finger resting on the actuating surface.This haptic perception serves, for example, as a confirmation signal for a touch or actuation, or as a haptic acknowledgement of a switching or control input. The actuator is preferably an inertial, motor-based actuator, such as a motor with a mass mounted eccentrically with respect to its center of gravity on its rotating drive shaft, or a magnetic coil actuator, a piezoelectric actuator, or a linear broadband actuator, such as a voice coil actuator or a linear resonance actuator. The actuator is preferably fixed exclusively to the actuating part, for example, by screwing or gluing.

[0008] According to the invention, the dynamic stiffness, which is understood as the local quotient of the local dynamic elastic modulus and the local thickness of the actuating part, varies along a maximum 1 cm long measuring section leading from the actuating section into or through the insulating section and lying on the visible surface in such a way that a first transfer function determined at a start of the measuring section located in the actuating surface differs by at least 5 dB, preferably at least 10 dB, for a contiguous frequency range between 30 Hz and 1,000 Hz from a second transfer function determined at an end of the measuring section located outside the actuating surface for the same frequency range. For example, the end lies within an insulating surface assigned to the insulating section, for example at its outer edge furthest away from the actuating surface.For example, the transfer function is determined for an identical electrical excitation signal, band-limited to 10 Hz to 4,000 Hz, formed as white noise, pink noise or as a multi-sine.

[0009] The inventive design of the isolation section ensures that, with an excitation spectrum of the excitation signal typical for haptic excitation, a significant damping of the vibration transmission into the area of ​​the actuating part located outside the actuating section is achieved. Thus, the haptic feedback is limited to the actuating section with its actuating surface in its maximum spectral range and is damped outside of this so that the operator can haptically localize the haptic feedback to the actual actuating surface located in the visible area. This also minimizes sound transmission into the area outside the actuating section. The haptic feedback is thus not only better bound locally to the actuating surface but also improved overall.

[0010] Preferably, the electrical excitation signal intended for haptic stimulation is band-limited such that its excitation spectrum, namely the amplitude spectrum of the excitation signal, lies between 30 Hz and 1,000 Hz, preferably between 40 Hz and 600 Hz, and at least partially or entirely encompasses the previously described frequency range. Preferably, the excitation spectrum of the excitation signal lies entirely, 80%, or at least predominantly within the aforementioned frequency range. Band-limited, in the context of the invention, means that the excitation spectrum has a 3 dB bandwidth around a maximum. The cutoff frequencies are set at half the maximum, which corresponds to a reduction to approximately 3 dB.

[0011] The variation in dynamic stiffness is preferably brought about by a change in the thickness of the actuating part determined perpendicular to the visible surface and / or a local change in the material composition of the actuating part. This is preferably a sudden change. A transition is understood to be sudden or discontinuous if the resulting dynamic stiffness at least doubles or at most halves within a section of 1 mm along the measuring section. For example, the sudden change causes an abrupt change in the wave impedance, resulting in reflections in the actuating section and thus attenuation during sound transmission from the actuating section. For example, the sudden change in the material composition and / or the thickness of the actuating part defines the outer boundary of the actuating surface and thus the actuating section.For example, the thickness of the actuating section is essentially constant, except for possible thickness variations, such as webs or holes, for fastening the actuator.

[0012] Preferably, the change in thickness is formed by a groove provided on the side of the actuating part facing away from the operator, wherein the inner flank of the groove closer to the actuating surface is the sudden change in thickness.

[0013] Preferably, the duration of the electrical excitation signal is limited to less than 100 ms, preferably less than 25 ms, in order to reduce low-frequency components in the excitation spectrum.

[0014] Preferably, the insulation section is formed to completely surround the actuating section.

[0015] Preferably, the actuating part is formed, at least in the actuating section, by a layer structure of at least two layers, wherein at least two layers differ in the modulus of elasticity.

[0016] In this case, one layer of the layer structure is preferably a high-strength layer made of a material with the largest modulus of elasticity of the layer structure, which extends substantially parallel to the actuating surface, for example between the actuator and the actuating surface.

[0017] Preferably, a layer thickness of the high-strength layer in the insulation section is reduced to provide the change in thickness.

[0018] Preferably, the high-strength layer is formed from a thermoplastic material, such as polycarbonate or polymethyl methacrylate, in particular a fiber-reinforced thermoplastic material, in order to impart a comparatively high rigidity to the actuating section.

[0019] According to a preferred embodiment, the layer structure comprises a highly elastic layer made of a material with the smallest modulus of elasticity of the layer structure, which has the greatest layer thickness of all layers involved in the insulation section within the insulation section in order to provide its flexibility.

[0020] Preferably, the highly elastic layer is made of a thermoplastic elastomer.

[0021] Preferably, the layered structure includes an additional layer to provide the material change and the thickness change in the insulation section. For example, the layer comprises a material with a higher acoustic damping effect than any material of the actuating part in the actuating section.

[0022] Preferably, the actuating surface constitutes less than half, preferably less than 1 / 5, more preferably less than 1 / 10 of the visible surface of the actuating part facing the operator. The actuating surface preferably does not exceed a maximum diameter of 2 cm.

[0023] According to a preferred embodiment, several actuation sections with associated actuators and surrounding insulation sections are provided. The embodiment according to the invention thus makes it possible, even with multiple actuation surfaces, to haptically locate them due to the locally limited effect of the haptic feedback, without the need for visual inspection. This is particularly advantageous for use in motor vehicles, since the driver lacks the time for visual inspection in most installation locations. For example, by individualizing the haptic feedback using specific excitation spectra, it is possible to give the operator the opportunity to haptically locate specific actuation surfaces on the visible surface based on the haptic feedback.

[0024] For the reasons stated above, the invention further relates to the use of the control element according to the invention in one of its previously described embodiments in a motor vehicle.

[0025] The invention is explained in more detail with reference to the following figures. These figures are to be understood as examples only and each represents only a preferred embodiment. They show: Fig. 1 shows a sectional view of an embodiment of the control element 1 according to the invention; Fig. 2 shows a spectral representation of the first and second transfer functions; Fig. 3 shows an electrical excitation signal in the time representation.

[0026] Figure 1 shows a first embodiment of the operating element 1 according to the invention. It serves to make an operating input by means of a movable actuating part 2 within the framework of a human-machine interface.

[0027] The control element 1 according to the invention has a carrier 2. The term "carrier" is to be interpreted broadly and refers, for example, to a component that serves to secure the control element to a supporting structure or, for example, is directly or indirectly attached to a motor vehicle component. Here, the carrier 2 is designed as a housing and is not visible to the operator when the control element 1 is properly attached. The carrier 3 is made of a plastic, a metal, or a metallic alloy, such as ZAMAK, or combinations thereof, and further serves to secure a printed circuit board 7, which carries the detection means 8, 9 for touch or actuation detection, such as a capacitive force sensor 8 and a microprocessor 9.

[0028] The operating element 1 according to the invention further comprises an actuating part 3 supported on the carrier 2, which forms a visible surface 10 facing an operator, which forms at least one island-shaped actuating surface 11 within the visible surface 10, wherein the actuating surface 11 is formed by a self-supporting actuating section 6 of the actuating part 3; and the actuating section 6 is surrounded by an insulating section 5 of the actuating part 3 which is more flexible than the actuating section 6, so that the actuating section 6 is mounted relative to the carrier 2 so as to be capable of oscillation, in particular in the direction perpendicular to the actuating surface 11.

[0029] According to the invention, an actuator 4 is further provided on the actuating section 6, from the operator's perspective, below the actuating section 6 or on its side facing away from the operator, which actuator 4, in the event of positive detection of an actuation or contact, is supplied with an electrical excitation signal I(t) by the detection means 8, 9 to excite a vibration of the actuating section 6 for haptic feedback. The actuator 4 is an active actuator, i.e., an actuator that can be triggered by an electrical control signal provided by the detection means 8, 9. By applying a pulse, such as an impact or vibration, to the actuating section 6 of the actuating part 3, it is capable of exciting a deflection or vibration therein, which can be haptically perceived by the operator via the finger resting on the actuating surface 11.This haptic perception serves, for example, as a confirmation signal for a touch or actuation, or as a haptic acknowledgment of a switching or control input. The actuator 4 is preferably a voice coil actuator or a linear resonance actuator. In the embodiment shown, the actuator 4 is fixed exclusively to the actuating part 3, for example, by screwing or gluing. The actuating surface 11 preferably makes up less than half, preferably less than 1 / 5, more preferably less than 1 / 10 of the visible surface 10 of the actuating part 3 facing the operator. The actuating surface 11 preferably does not exceed a maximum diameter of 2 cm.

[0030] Due to the structure of the actuating part 3, the dynamic stiffness, which is understood as the local quotient of the local dynamic elastic modulus and the local thickness of the actuating part, varies along a measuring section s leading from the actuating section 6 into or through the insulating section 5, a maximum of 1 cm long, lying on the visible surface 10 in such a way that a first transfer function U 1 determined at a start X 1 of the measuring section s located in the actuating surface 11 differs for a continuous frequency range between 30 Hz and 1,000 Hz by at least 5 dB from a second transfer function U 2 determined at an end X 2 of the measuring section s located outside the actuating surface for the same frequency range, as shown in Figure 2is shown. For example, the end X 2 lies beyond the insulation section, i.e. in a part of the visible surface 10 outside the insulation surface assigned to the insulation section 5 and outside the actuation surface 11. For example, the transfer function for an identical electrical excitation signal I(t) applied to the actuator 4, band-limited to 10 Hz to 4,000 Hz, in the form of white noise, pink noise, or a multi-sine wave, is determined by a vibration sensor, such as a piezoelectric transducer or a laser vibrometer.

[0031] The inventive design of the insulation section 5 ensures that, with an excitation spectrum typical for haptic excitation, as is exemplified in the Figure 2marked as X f , which should result from the excitation signal I(t), a significant damping of the vibration transmission into the area of ​​the actuating part 3 lying outside the actuating section 6 is achieved and thus the haptic feedback is limited in its maximum spectral range to the actuating section 6 with its actuating surface 11 and is damped outside of this so that the operator is able to haptically localize the haptic feedback to the actual actuating surface 11 lying in the visible surface 10. This also leads to the sound transmission into the area outside the actuating section 6 being minimized. The haptic feedback is thus not only better bound locally to the actuating surface 11 but is also improved overall.

[0032] The electrical excitation signal intended for haptic stimulation is band-limited such that its excitation spectrum lies between 30 Hz and 1,000 Hz, preferably between 40 Hz and 600 Hz, and at least partially or entirely covers the previously described frequency range Xf. Preferably, the excitation spectrum of the excitation signal lies entirely, 80%, or at least predominantly in the previously mentioned frequency range Xf.

[0033] The aforementioned variation in dynamic stiffness is caused by a change in the thickness of the actuating part 3, determined perpendicular to the visible surface, and / or a local change in the material composition of the actuating part 3. This is a sudden change. A transition is understood to be sudden or discontinuous if the resulting dynamic stiffness at least doubles or at most halves within a 1 mm long section along the measuring section s. In the embodiment shown, the change in thickness is formed by a groove 12 provided on the side of the actuating part 3 facing away from the operator, wherein the inner flank of the groove 12 closer to the actuating surface 11 is the sudden change in thickness.

[0034] How Figure 3 shows, the duration of the electrical excitation signal is limited to less than 100 ms, preferably less than 25 ms, in order to reduce low-frequency components in the excitation spectrum.

[0035] How Figure 1 shows, the actuating part 3 is formed, at least in the actuating section, by a layer structure of several layers 3a, 3b, 3c, wherein at least two layers 3a, 3b differ in the modulus of elasticity.

[0036] One layer of the layer structure is a high-strength layer 3b made of a material with the largest modulus of elasticity of the layer structure, which extends essentially parallel to the actuating surface 11, here between the actuator 4 and the actuating surface 11.

[0037] Furthermore, the layer thickness of the high-strength layer 3b in the insulation portion is reduced to zero to provide the aforementioned change in thickness.

[0038] The high-strength layer 3b is formed from a thermoplastic material, such as polycarbonate or polymethyl methacrylate, in particular a fiber-reinforced thermoplastic material, in order to impart a comparatively high rigidity to the actuating section 6.

[0039] The layered structure further comprises a highly elastic layer 4a made of a material with the smallest modulus of elasticity of the layered structure, which, within the insulation section, has the greatest layer thickness of all layers 3b, 3c involved in the insulation section 5 to provide its flexibility. Layer 3c, which completely covers the visible surface 10, is merely a comparatively thin cover layer, such as a transparent film.

[0040] The highly elastic layer 3a is made of a thermoplastic elastomer.

Claims

1. An operating member (1), comprising: a carrier (2); an actuation part (3), which is supported on the carrier and which forms a visible surface (10) facing towards an operator that forms at least one insular actuation surface (11) within the visible surface (10), wherein the actuation surface (11) is formed by a cantilevered actuation portion (6) of the actuation part (2); and the actuation portion (6) is surrounded by an insulation portion (5) of the actuation part (3), which is more flexible compared to the actuation portion (6), so that the actuation portion (6) is supported so as to be capable of vibrating relative to the carrier (2); detection means (8, 9) for detecting a touch on the actuation surface and / or an actuation of the actuation part (3); an actuator (4) fixed on the actuation portion (6) of the actuation part (3) on the side that, from the point of view of the operator, faces away from the operator, to which an electrical excitation signal (I(t)) is applied by the detection means (8, 9) in case of a positive detection of an actuation or touch, in order to excite a vibration of the actuation portion (6) for a haptic feedback; wherein a dynamic rigidity of the actuation part (2) determined along a measurement section (s) with a maximum length of 1 cm, leading from the actuation portion (6) in or through the insulation portion (5) and located on the visible surface, varies such that a first transfer function (U1) determined at a beginning (x1) of the measurement section (s) differs, for a continuous frequency range (XF) between 30 Hz and 1,000 Hz, by at least 5 dB from a second transfer function (U2) determined at an end (x2) of the measurement section (2) for the same frequency range.

2. The operating member (1) according to claim 1, wherein the electrical excitation signal (I(t)) has an excitation spectrum between 30 Hz and 1,000 Hz, preferably between 40 Hz and 600 Hz, which at least partially, preferably completely, includes the frequency range (XF).

3. The operating member (1) according to any one of the preceding claims, wherein the variation of the dynamic rigidity is caused by a change in the thickness determined perpendicularly to the visible surface and / or a change in the material composition of the actuation part (2), a preferably sudden change.

4. The operating member (1) according to the preceding claim, wherein the change in thickness is formed by a groove (12) provided on the side of the actuation part (2) facing away from the operator (B).

5. The operating member (1) according to any one of the preceding claims, wherein a duration of the electrical excitation signal is limited to less than 100 ms, preferably less than 25 ms.

6. The operating member (1) according to any one of the preceding claims, wherein the insulation portion (5) is formed so as to extend completely around the actuation portion (6).

7. The operating member (1) according to any one of the preceding claims, wherein the actuation part (3), at least in the actuation portion, is formed by a layer structure consisting of at least two layers (3a, 3b, 3c), wherein at least two layers (3a, 3b) differ with regard to the modulus of elasticity.

8. The operating member according to the preceding claim, wherein one layer of the layer structure is a high-strength layer (3b) of a material with the greatest modulus of elasticity of the layer structure, which extends substantially parallel to the actuation surface (3).

9. The operating member (1) according to the preceding claim, wherein a layer thickness of the high-strength layer (3b) is reduced in the insulation portion (5) in order to provide the change in thickness.

10. The operating member (1) according to any one of the two preceding claims, wherein the high-strength layer (3b) is formed from a thermoplastic, such as polycarbonate or polymethyl methacrylate, in particular a fiber-reinforced thermoplastic.

11. The operating member (1) according to any one of the preceding claims 7 to 10, wherein the layer structure has a highly elastic layer (3a) of a material with the smallest modulus of elasticity of the layer structure, which, within the insulation portion (5), has the greatest layer thickness of all layers involved in the insulation portion (5).

12. The operating member (1) according to the preceding claim, wherein the highly elastic layer (3a) is formed from a thermoplastic elastomer.

13. The operating member (1) according to any one of the preceding claims 7 to 12, wherein the layer structure has an additional layer for providing the change in material and the change in thickness.

14. The operating member (1) according to any one of the preceding claims, wherein the actuator (4) is supported exclusively on the actuation part.

15. The operating member (1) according to any one of the preceding claims, wherein the actuation surface (11) constitutes less than half, preferably less than 1 / 5, of a visible surface (10) of the actuation part (3) facing towards the operator.

16. The operating member (1) according to any one of the preceding claims, wherein several actuation portions (6) with an associated actuator (4) and a surrounding insulation portion (5) are provided.

17. The operating member (1) according to any one of the preceding claims, wherein the actuation surface (11) does not exceed a maximum diameter of 2 cm.

18. Use of the operating member (1) according to any one of the preceding claims 1 to 17 in a motor vehicle.