阅读说明：本技术 设置有加强件的触觉反馈装置 (Haptic feedback device provided with a stiffener ) 是由 M·鲁平 于 2020-04-25 设计创作，主要内容包括：本发明涉及一种触觉反馈装置(1；10),包括支撑件(4),其能够振动并且其第一面涂覆有至少一个层(2、3),该层结合有用于检测用户的手指的位置的检测装置,所述装置(1；10)包括机电致动器(12),其沿着支撑件(4)或层(2、3)的边缘对齐并且能够使所述支撑件(4)和所述层(2,3)以超声波谐振频率振动,其特征在于,所述支撑件(4)在其第二面上包括一组加强件(5),该组加强件分布在整个该第二面上并被构造为使支撑件(4)沿着垂直于加强件(5)的轴线的弯曲更难,加强件(5)被设置成获得支撑件(4)的轴向且均匀的振动模式,该振动模式的所有波腹都具有基本相等的振幅。(The invention relates to a haptic feedback device (1; 10) comprising a support (4) which can vibrate and of which a first face is coated with at least one layer (2,3) incorporating detection means for detecting the position of a user's finger, said device (1; 10) comprising an electromechanical actuator (12) aligned along the edge of the support (4) or layers (2,3) and capable of vibrating said support (4) and said layers (2,3) at an ultrasonic resonance frequency, characterized in that said support (4) comprises, on its second face, a set of stiffeners (5) distributed over the entire second face and configured to make bending of the support (4) along an axis perpendicular to the stiffeners (5) more difficult, the stiffeners (5) being arranged to obtain an axial and uniform vibration mode of the support (4), all antinodes of the vibration mode have substantially equal amplitudes.)

1. Haptic feedback device (1; 10) comprising a support (4) which can vibrate and of which a first face is coated with at least one layer (2,3) incorporating detection means for detecting the position of a user's finger, said device (1; 10) comprising an electromechanical actuator (12) which is aligned along an edge of said support (4) or layer (2,3) and which is able to vibrate said support (4) and said layer (2,3) at an ultrasonic resonance frequency, characterized in that said support (4) comprises on its second face a set of stiffeners (5) distributed over the entire second face and configured to make more difficult the buckling of said support (4) along an axis perpendicular to said stiffeners (5), said stiffeners (5) being arranged to obtain an axial and uniform vibration mode of said support (4), all antinodes of the vibration modes have substantially equal amplitudes.

2. The device according to claim 1, characterized in that the stiffener (5) is configured to obtain an axial vibration mode, the nodal lines of which are parallel to the alignment lines of the electromechanical actuator (12).

3. The device according to claim 1, characterized in that the stiffener (5) is configured to obtain an axial vibration mode with nodal lines perpendicular to the alignment lines of the electromechanical actuator (12).

4. Device according to any one of the preceding claims, characterized in that the electromechanical actuators (12) are arranged along a line parallel or perpendicular to the stiffener (5).

5. Device according to any one of the preceding claims, characterized in that the support (4) is made of metal, glass, ceramic or plastic material in the glass phase.

6. Device according to any one of the preceding claims, characterized in that said first face of said support (4) is covered by a thin layer of material (wood, plastic) having sufficiently low viscoelastic losses not to impair said ultrasonic resonance of said support (4).

7. Device according to any one of the preceding claims, characterized in that at least one layer (2,3) arranged above the support (4) integrates a display device (3), all layers of which are integral between each other and are capable of transmitting vibrations at ultrasonic frequencies.

8. Device according to claim 7, characterized in that the display device (3) is an OLED screen.

9. Device according to any one of the preceding claims, characterized in that the actuation frequency of the electromechanical actuator (12) is an ultrasonic frequency comprised between 20 and 200 kHz.

10. Device according to any one of the preceding claims, characterized in that said reinforcement (5) forms parallel rectilinear grooves provided on said second face of said support (4).

11. Device according to claim 10, characterized in that said grooves are obtained by machining said support (4) so as to leave a reinforcement (5) raised with respect to said second face of said support (4).

12. Device according to any one of the preceding claims, characterized in that said reinforcement (5) is attached and glued to said second face of said support (4).

13. Device according to any one of claims 1 to 11, characterized in that the support (4) and its reinforcement (5) are manufactured by injection.

14. The device according to any one of the preceding claims, optimized for a resonance frequency of 20kHz of the support (4), characterized in that the support (4) is a plate with a thickness of 2mm and in that the stiffeners (5) are raised with respect to the plate by a thickness of 2mm and have a width of 5mm and are spaced apart by a distance of 5 mm.

15. The device according to any one of claims 1 to 13, optimized for a resonance frequency of 200kHz of the support (4), characterized in that the support (4) is a plate with a thickness of 2mm and in that the stiffeners (5) are raised with respect to the plate by a thickness of 1mm and have a width of 1.2mm and are spaced apart by a distance of 1.8 mm.

Technical Field

The invention relates to a tactile feedback surface based on the ultrasonic lubrication principle.

Background

Such haptic feedback devices are already known: wherein the vibration propagation medium is a thin plate capable of vibrating. A plate is said to be "thin" when it has a small thickness compared to the other two dimensions and compared to the wavelength of the vibration wave under consideration.

In a known manner, the plate may be monolithic or multilayered and rectangular in shape. The electromechanical actuator is arranged on the plate to excite an axial vibration mode, i.e. its vibration nodes are aligned with each other along a line parallel to one of the edges of the plate.

In a plate whose thickness does not exceed twice the wavelength of the vibrations produced by the actuator, a bending wave called λ -wave a0 (or quasi λ -wave in the case of a multilayer plate of asymmetric thickness) is produced and reflected on two boundaries parallel to the alignment line of the actuator.

When the actuation frequency is properly adjusted, a steady state mode is excited, which will act as an amplifier through resonance effects. The large displacement amplitude obtained at the ultrasonic frequency therefore results in the generation of a cushion of compressed air under the antinode of the user's finger (the so-called "squeeze film" effect of english terminology). The finger is pushed away by the surface, the coefficient of friction is reduced and a haptic feedback effect is obtained upon movement of the finger. This is called ultrasonic lubrication.

However, this approach has a disadvantage. In fact, in order to obtain a uniform haptic feedback effect at all points of the surface, it is crucial that the vibration of the plate is as uniform as possible. However, for example, when the aspect ratio (length to width) of the surface to be actuated is close to 1, then there is a superposition of two modes at substantially the same resonant frequency, one along the axis X and the other along the axis Y, which disturbs the modal deformation by creating interference. This phenomenon deteriorates the actuation efficiency of the linear branch (antene) of the actuator due to the incompatibility between the position of the actuator and the change in modal deformation. The actuators can no longer be actuated by a single signal because they no longer vibrate in phase.

In addition to square supports, supports of other shapes are also subject to such degradation: in fact, this occurs when trying to obtain axial resonance modes by a row of actuators on different supports than rectangular supports (for example complex geometries combining curved edges and straight or non-parallel edges).

Other problems may be added to the interference problems, such as the problem of focusing of the waves, which may lead to local overload currents and thus to variability of the vibration amplitude of the support, for example on supports where concavities occur, and in extreme cases when the support is in the shape of a disc.

From document EP 3287880 a1 a haptic device is known which is provided with a plate which is vibrated at ultrasonic frequencies by means of a piezoelectric actuator and which has underneath it, at certain specific locations, grooves or periodic structures of locally reduced thickness. Such a periodic structure acts as a bragg reflector, allowing to confine the standing wave to a region defined around the actuator, in particular to a region of the plate that should selectively vibrate in response to a contact by a user's finger. Since only actuators located near the area touched by the user vibrate, this structure seeks to target a limitation in energy consumption.

The periodic structure described in this document therefore produces the opposite effect to that sought by the present invention, which seeks to strongly excite a particular axial mode (unidirectional in X or Y) with satisfactory amplitude over an entire haptic feedback support of the ultrasonic lubrication type, regardless of the shape of the support, regardless of a rectangle, square, disc, or even any shape.

Disclosure of Invention

Object of the Invention

The general object of the present invention is to propose a solution for overcoming the limitations of the prior art, in particular for obtaining an axial mode exhibiting a very uniform unidirectional vibration over the whole support, regardless of the geometry and dimensions of the surface to be actuated, so as to guarantee an optimal actuation over the whole support by a row of actuators.

Summary of The Invention

The principle of the invention consists in modifying the structure of the surface of the support to be actuated in order to obtain a uniform vibration over the entire surface of the support. The support is initially isotropic, that is, the ultrasonic wave propagates at the same speed regardless of the direction. It involves making the support orthotropic to force an axial resonance effect in a specific direction of the support, regardless of the geometry of the support (e.g. square, rectangular, even circular disk or any shape).

This specific anisotropy or orthotropic anisotropy of the surface to be actuated is obtained by providing one-dimensional stiffeners distributed over the entire surface of the support, parallel to each other, and regardless of the geometry of the support. The actuators will then be arranged along lines parallel or perpendicular to these stiffeners. Thus, grooves are obtained on the face of the support which do not confine the vibrations to the region of the support as proposed in the above-mentioned document, but instead produce an effective propagation speed of the vibration wave which differs depending on whether the wave propagates parallel or perpendicular to these grooves.

The actuators are arranged along a line which is preferably parallel to the stiffener, but which may also be perpendicular to the stiffener.

Experience has shown that this method is effective regardless of the shape of the surface, although its practical application will involve more square or rectangular surfaces.

The object of the present invention is therefore a haptic feedback device comprising a support capable of vibrating and coated on a first face with at least one layer incorporating detection means for detecting the position of a user's finger. The device comprises an electromechanical actuator aligned along an edge of the support or the layer and capable of vibrating the support and the layer at an ultrasonic resonance frequency, characterized in that the support comprises on its second face a set of stiffeners distributed over the entire second face and configured to make more difficult the buckling of the support along an axis perpendicular to the stiffeners, the stiffeners being arranged so as to obtain an axial and uniform vibration mode of the support, the amplitude of all antinodes of which is substantially equal.

According to one embodiment, the stiffener is configured to obtain an axial vibration mode having nodal lines parallel to the alignment lines of the electromechanical actuator.

According to another embodiment, the stiffener is configured to obtain an axial vibration mode having a nodal line perpendicular to an alignment line of the electromechanical actuator.

According to one embodiment, the electromechanical actuators are arranged along a line parallel or perpendicular to the stiffener.

According to one embodiment, the support is made of metal, glass, ceramic or a plastic material in the glass phase.

According to one embodiment, said first face of said support is covered by a thin layer of material (wood, plastic material) exhibiting a sufficiently low loss of viscoelasticity not to impair the ultrasonic resonance of said support.

According to one advantageous embodiment, at least one layer integrated display device, in particular an OLED screen, is arranged above the support, all layers of which are integral with one another and are capable of transmitting vibrations at ultrasonic frequencies.

According to various embodiments, the actuation frequency of the electromechanical actuator, for example a piezoceramic electromechanical actuator, is an ultrasonic frequency between 20kHz and 200 kHz.

The reinforcing members form parallel linear grooves provided on the support member. From an industrial point of view, it can be obtained in various ways. Thus, it may in particular be machined directly in the support, or attached and glued to this same support. However, the support and its reinforcement can also be realized in a single operation by injection.

The stiffeners, as the name implies, make buckling of the plate along an axis perpendicular to the stiffeners more difficult. Since the bending wave will propagate more slowly along an axis perpendicular to the stiffeners, this manifests itself in a difference in the propagation speed of the bending wave in the case of ultrasonic vibration of the plate. Thus, since the reinforcement promotes the occurrence of specific axial modes, the reinforcement allows to avoid or minimize the formation of destructive interferences between bending waves caused by the actuation of the plates.

According to one embodiment optimized for the resonance frequency of a 20kHz plate, the plate has a thickness of 2mm and the stiffeners have a thickness of 1mm and a width of 5mm and are spaced apart by a distance of 5 mm.

According to one embodiment optimized for the resonant frequency of a 200kHz plate, the plate has a thickness of 2mm and the stiffeners have a thickness of 1mm and a width of 1.2mm and are spaced apart by a distance of 1.8 mm.

Drawings

The invention will be described in more detail with the aid of the accompanying drawings, in which:

fig. 1 shows the modal deformation at the natural frequency of a rectangular plate made of purely elastic material;

fig. 2 shows the modal deformation of a square plate made of purely elastic material, corresponding to the interference between two axial modes in x and in y coexisting at the same frequency;

figure 3 shows a perspective view of a first embodiment of the invention;

figure 4 shows the modal deformation of a square plate made of rigid material provided with a stiffener according to the invention;

figure 5 shows a perspective view of a particular embodiment of the invention suitable for an ultrasonic vibration frequency of 20 kHz;

figure 6 shows a perspective view of a particular embodiment of the invention suitable for an ultrasonic vibration frequency of 200 kHz;

figure 7 shows a partial cross-section of an OLED screen according to the invention, integrating a support made of rigid material capable of vibrating.

Detailed Description

Refer to fig. 1. When the aspect ratio (width to length) of a rectangular plate is less than/, a bending vibration mode called axial, i.e. with nodes parallel to one of the edges of the plate and antinodes of vibration, is obtained. This type of vibration is advantageous because it can be effectively obtained by a set of electromechanical actuators arranged along a line parallel to the vibration node. In the example shown, the plates have the following dimensions: 12 cm x 7 cm x 2 mm. The plate is actuated by normal forces applied to the four corners. Fig. 1 corresponds to an excitation frequency of 42 kHz.

Figure 2 shows the vibrational response of a square plate of dimensions 12 cm x 12 cm x 2mm under the same excitation as the rectangular plate of figure 1. This time, the spatial deformation is no longer oriented along the axis of the plate, but has a circular vibration antinode. In practice, this corresponds to a superposition of 2 axial modes, these 2 axial modes being called degenerate modes since they occur at the same frequency (here 42318 Hz). In this case, this type of actuation of the vibration modes can no longer be effectively achieved by actuators arranged along the line.

In fig. 3, the principle of the solution according to the invention is schematically shown: the device 1 comprises a plurality of layers 2,3, 4. The plate 4 is a rigid plate (made of glass or metal, for example) capable of vibrating, provided with piezoelectric actuators (not shown). The raised stiffener 5 is attached to the underside of the panel 4, i.e. the side of the panel opposite to the side carrying the upper layers 2, 3. In the example shown, the stiffener 5 is in the shape of a parallelepiped with a rectangular cross section, but other transverse cross-sectional shapes are possible. With the spaces 6 between the stiffeners 5, grooves are obtained which allow to create an orthogonal anisotropy in the propagation velocity of bending waves, in particular λ -waves a 0.

In the embodiment shown in fig. 3, the device 1 has a composite structure. It comprises 3 superimposed elements, namely for example an upper glass plate 2 ("cover glass" in english terminology), a set of polymer layers 3 forming the OLED screen, and an aluminium plate 4 provided with a reinforcement 5. The OLED screen 3 comprises a plurality of layers in a manner known per se. These layers are not shown or described in detail herein.

In a possible variant embodiment, the upper layer 2 of the device 1 may optionally be constituted by a thin layer of non-elastic material, optionally opaque (wood, plastic), so as to provide a viscoelastic loss low enough not to compromise the ultrasonic resonance of the support.

However, the invention is particularly useful for devices 10 that integrate OLED screens, as shown in cross-section in fig. 7. The OLED screen 3 is integrated into the frame 11. Which comprises a cover glass 2 ("cover glass") on top. The piezoelectric actuator 12 is glued under and aligned with the lateral edge of the cover glass 2, allowing the assembly (2,3) to vibrate. As a variant, the actuator 12 may be glued under the plate or support 4 in order to vibrate the assembly constituted by the plate 4 and the layers 2, 3. The actuator 12 is powered by a known control circuit (not shown). In a known manner, the cover glass 2 comprises a capacitive layer (not shown), allowing the device 10 to have a tactile feel and to detect the movement of the user's finger. The metal plate 4 abuts against the underside of the OLED screen. The free lower face of the metal sheet 4 is provided with a raised reinforcement 5. Which allows a user touching the area of the screen above the upper glass plate 2 to experience better tactile feedback than a tactile feedback screen without a stiffener.

This is confirmed in fig. 4, which shows the axial pattern obtained after the integration of the stiffeners 5 under the plate 4. The mode along the axis resonates at 43634 Hz, while the mode along the perpendicular axis resonates at 53634 Hz. Thus, the axial modes are now clearly separated in frequency. The anisotropy provided by the stiffeners 5 causes a difference in propagation velocity between bending waves propagating along the axis X of the plate and bending waves propagating along the axis y of the plate. By contrast, it is thus possible to actuate the axial mode in a square plate with optimum efficiency by means of a set of actuators aligned along a line parallel to one of the edges of the square plate, that is to say a greater amplitude of vibration of the plate can be obtained in a uniform manner on the surface of the square plate, but with reduced energy consumption.

This is because the stiffeners make buckling of the plate along an axis perpendicular to the stiffeners more difficult, which in the case of ultrasonic vibration of the plate is not caused by local confinement of the bending waves, but by differences in the propagation velocities of the bending waves.

The plate 4 on which the reinforcement 5 is provided may itself be monolithic or multi-layered. The stiffener 5 has a cross-section of any shape, but for ease of manufacture it is preferably rectangular.

In practice, the stiffeners 5 may be manufactured in any useful way, for example by milling on a metal plate, or by stiffeners attached and then glued on the underside of the plate 4.

To ensure an optimum actuation, the stiffeners 5 of the plate 4 will be positioned on the antinodes of vibration and the vibration of the assembly will be uniform.

FIG. 5 shows a particular embodiment, which corresponds to the thickness (e)_p) The lower point of the vibration frequency of the actuator on the metal plate 4 of 2mm, i.e. 20 kHz. In this case, good results are obtained when the reinforcement 5 is dimensioned as follows:

-thickness: es = 2mm

-width: ls = 5mm

-pitch: b = 5mm

-length: length or width of the panel

FIG. 6 shows another particular embodiment, which corresponds to the thickness (e)_p) The high point of the vibration frequency of the actuator on the metal plate 4 of 2mm, i.e. 200 kHz. In this case, good results are obtained when the reinforcement 5 is dimensioned as follows:

-thickness: es = 1mm

-width: ls = 1.2mm

-pitch: b = 1.8mm

-length: length or width of the panel

Other optimal dimensions of the stiffeners may be selected for values of resonant frequency between 20kHz and 200 kHz.

THE ADVANTAGES OF THE PRESENT INVENTION

The invention achieves the determined aim.

In particular, by using stiffeners, it allows to obtain a greater amplitude of the vibrations of the plate, with a reduced energy consumption.

The invention is ideally suited for any product that includes an opaque layer that allows masking of the stiffener: switches, touch panels, screens with optical adhesive that can be activated under the display surface (OLED type).

It can guarantee a uniform vibration on the surface of a rigid material capable of vibrating, regardless of its shape, to obtain the same tactile feedback at all points of its surface.