Haptic and sound interface

Abstract

Haptic and Sound Interface: A multimodal haptic interface comprising: - a control circuit (3), - a matrix comprising a plurality of ultrasonic transducers (2) connected to said circuit, the control circuit being configured to modulate the signals (30) sent to the transducers (2) in order to: - generate, with the ultrasonic waves emitted by at least some of the transducers, a tactilely detectable acoustic pressure in at least a first focal zone (10), and / or - generate, with the ultrasonic waves emitted by at least some of the transducers, an audibly detectable acoustic pressure in at least a second focal zone (11). Figure for the abbreviation: Fig. 1A

Description

Title of the invention: Haptic and sound interface Technical field

[0001] The present invention relates to human-machine interfaces, and more particularly those using haptic and sound effects. Prior art Haptic interface

[0002] A haptic interface allows the user to interact with the environment through the sense of touch. The haptic effect is now increasingly used in many applications, particularly for virtual or augmented reality devices.

[0003] It is known to use a matrix of ultrasonic transducers excited at a frequency greater than 20 kHz, called the carrier frequency, to generate a plurality of ultrasonic waves which, not audible, are focused by acting on the phase shift of the carriers in a predefined area of ​​space, to generate an acoustic pressure. The latter is perceptible to the touch thanks to a low-frequency modulation of the amplitude of the carriers.

[0004] In the following, by "carrier frequency of the transducers" we mean the frequency of the excitation signal of the transducers, in other words their working frequency, excitation signal which can be modulated in amplitude to generate the haptic or sound information which we seek to transmit.

[0005] It is known in particular to actuate transducers individually or in groups to generate a non-audible acoustic pulse ("pulse"), control electronics being arranged to judiciously phase-shift the actuation of each transducer in order to focus the ultrasonic waves at a chosen point in space. This single-point acoustic focusing technique makes it possible to add the elementary acoustic pulses and therefore to generate acoustic pulses strong enough to be felt by the user.

[0006] This technology generating a remote effect allows for example better immersion in video games, in particular via the addition of haptic effects when using virtual reality (VR), augmented reality (AR) or mixed reality (MR) glasses. It can also be applied to the functionalization of dashboards, in particular automotive ones, by allowing the driver to obtain tactile information while keeping his attention on the road.

[0007] Application US20180181203 discloses a haptic interface for generating a haptic effect on a user's hand using a matrix of ul- transducers trasonics whose carrier frequencies are identical, but whose low-frequency modulation frequencies are different, in order to solicit different tactile receptors sensitive to different excitation frequencies and thus create a multipoint haptic effect.

[0008] Application FR3092680 describes a virtual reality device comprising a mount intended to be worn on a user's head and comprising a plurality of identical ultrasonic transducers of the micro-machined piezoelectric type (PMUT) generating a haptic effect on the user's hand.

[0009] Application FR3116630 describes a “remote” type haptic interface comprising two sets of transducers emitting at different carrier frequencies. Sound interface

[0010] Loudspeakers are known which receive an analog signal and comprise a membrane which will reproduce the sound to be played depending on its position and its movement.

[0011] It is also known to use a large number of small transducers to reconstruct a sound to be played by the principle of linear additivity of pressures in the air, as described in the article by Dejaeger et al, “Development and characterization of a piezoelectrically actuated MEMS digital loudspeaker”, Proceedings European Conference on Sensors, Actuators and Microsystems (Eurosensor), 2012, as well as in the thesis Rémy Dejaeger, Modélisations multiphysiques, réalisation et expériences d'un haut-parleur digital matriciel piezoélectrique MEMS, Acoustique [physics.class-ph], INSA de Lyon, 2014, French. In these documents, a certain number of transducers are activated in order to obtain an overall pressure pulse of a certain amplitude. Multimodal system

[0012] Systems are known from the state of the art which combine both haptic and visual effects, thanks to the use of separate systems, the visual effects being generated for example using holograms or mirrors, and the haptic effects by a matrix of ultrasonic transducers. Statement of the invention

[0013] There remains a need to benefit from an interface capable of generating both localized “mid-air” haptic effects and localized sound effects. Summary of the invention

[0014] The invention aims to meet this need and achieves this, according to a first of its aspects, thanks to a multimodal haptic and sound interface of the “remote” type, comprising: - a control circuit, - a matrix comprising a plurality of ultrasonic transducers connected to said circuit, the control circuit being configured to modulate the signals sent to the transducers in order to: - generate with the ultrasonic waves emitted by at least part of the transducers an acoustic pressure detectable tactilely in at least a first focal zone, and - generate with the ultrasonic waves emitted by at least part of the transducers an acoustic pressure detectable audibly in at least one second focal zone.

[0015] By "focal zone", sometimes also called "focal point", we mean the zone where the ultrasonic waves are concentrated and generate a detectable acoustic pressure. This focal zone can be a region of space of varying extent, depending on the objective pursued.

[0016] The interface according to the invention makes it possible to actuate transducers by introducing a phase shift on each actuated transducer, in order to spatially localize a haptic effect and / or a sound effect.

[0017] The invention makes it possible to generate spatially and / or temporally coherent sound and haptic effects.

[0018] The invention makes it possible to simultaneously generate the creation of haptic and sound effects, thanks in particular to different carrier frequencies of the transducers and / or different numbers of actuated transducers for the two effects and / or varied phase shifts between the transducers.

[0019] The invention also makes it possible to successively generate haptic and sound effects with the stimulation of the same transducers. The two successive effects can be perceived as simultaneous by a user if the time separating them is less than or equal to a few hundred, better a few tens, milliseconds, for example if the time separating them is less than or equal to 1000 ms, or even 100 ms.

[0020] The invention can make it possible to generate haptic effects having a spatial resolution (size of the focal spot) of between 1 mm and 30 cm, better still between 2 mm and 1 cm.

[0021] The invention can make it possible to generate sound effects having a spatial resolution of between 1 cm and 8 cm.

[0022] The invention can make it possible, if desired, to quickly move the first focal zone in order to give the user the impression of a large object. Control circuit

[0023] The control circuit is preferably configured to determine the number of transducers to be actuated to achieve desired haptic and / or sound effects, as well as their position in the transducer matrix.

[0024] The control circuit is preferably configured to calculate phase shifts to be introduced into the carriers of the different ultrasonic waves emitted by the actuated transducers, and to generate these phase shifts so as to concentrate the emitted ultrasonic waves into predefined focal zones.

[0025] The control circuit uses in particular algorithms known to those skilled in the art in order to determine the number of transducers to be actuated and / or their position and / or in order to calculate the phase shifts to be introduced into the carriers of the different ultrasonic waves emitted by the actuated transducers. Such an example of an algorithm known to those skilled in the art is described in the article Hudin C, Lozada J, Hayward V., Localized Tactile Feedback on a Transparent Surface through Time-Reversal Wave Focusing, IEEE Trans Haptics, 2015 Apr-Jun;8(2): 188-98.

[0026] The control circuit may receive data from equipment defining the haptic and / or sound effect(s) to be generated, depending for example on the position of the hand and / or ear of the person for whom this or these effect(s) is(are) intended, relative to the transducers. The control circuit may be configured to determine which transducers to actuate and the signals to be sent with them according to the desired haptic and / or sound effect(s). Multimodal interface

[0027] The interface may comprise at least one set of transducers arranged to generate haptic effects and sound effects.

[0028] The interface may comprise at least two sets of ultrasonic transducers, in particular having exactly two.

[0029] A first set of transducers may be arranged to generate haptic effects and a second set of transducers may be arranged to generate sound effects simultaneously and / or successively to the haptic effects generated by the first set, in particular a first set of transducers may be arranged with the control circuit to generate haptic effects and a second set of transducers not included in the first may be arranged to generate with the control circuit sound effects simultaneously and / or successively to the haptic effects generated by the first set.

[0030] Preferably, one of a first and a second set of transducers is at least partly, more preferably completely, included in the other of the first and the second set of transducers.

[0031] The two sets of transducers may comprise different numbers of transducers.

[0032] A first set may comprise between 100 and 200 transducers.

[0033] A second set may comprise between 200 and 500 transducers.

[0034] The transducers of a first set and those of a second set may have identical active membranes. The transducers of a first set and those of a second set may have active membranes of different sizes, preferably made identically.

[0035] The transducers of a first and a second set may operate with identical carrier frequencies. Alternatively, the transducers of a first and a second set may operate with different carrier frequencies.

[0036] The transducers can be arranged to operate at different carriers in several ways. For a given transducer, the carrier frequency can correspond to the resonance frequency of the transducer. For example, the size of the transducers or the materials used can be varied, both of these parameters having an effect on the resonance frequency. For example, the transducers of a first set and those of a second set have active membranes of different sizes, preferably made identically, in particular with the same material(s). This simplifies the production of the transducers, by allowing, if desired, the simultaneous production, for example on the same support, of a plurality of transducers, some with a given membrane size and others with a different size. The transducers having the largest active membrane can emit at the lowest carrier frequency.

[0037] The transducers of a first set and those of a second set can be amplitude modulated at an identical low frequency, or alternatively at different frequencies.

[0038] The low modulation frequency of the carriers is preferably between 10 Hz and 5 kHz, better between 50 Hz and 500 Hz.

[0039] The transducers of a first set can be grouped into one or more subsets, as can those of a second set.

[0040] The transducers of a first set and those of a second set are preferably carried by the same support. This support can be rigid or flexible, and take for example various configurations, in particular concave or convex, depending on the desired effects.

[0041] Preferably, the first focal zone is different from the second. The focal zones may be located at different places in space and / or be of different sizes.

[0042] The interface may comprise several, in particular two or three, sets of transducers arranged to simultaneously create haptic effects at different spatial positions. Detection system

[0043] The interface may comprise at least one detection system configured to detect the position relative to the transducers of at least one surface to be tactilely stimulated, and / or of at least one auditory receiver to be sound-stimulated.

[0044] The control circuit may be arranged to control the transducers, in particular the position of the first and second focal zones, as a function of the position of the surface and / or the auditory receiver.

[0045] The detection system can use for this detection at least some of the ultrasonic transducers, by analyzing the return signal reflected on the user, in the manner of a sonar. The detection system can also use any other system, for example optical or capacitive, suitable for this detection.

[0046] The detection system may be used, if necessary, to allow the interface to transition from a standby state to an active state, or vice versa. Transducers

[0047] Each transducer can be of any type, piezoelectric, ferroelectric, electromagnetic, thermal. For piezoelectric transducers, the materials can be deposited in thin layers or shaped from ceramic piezoelectric materials. Preferably, the transducer is of the piezoelectric type, in particular of the micro-machined piezoelectric type (PMUT), this type of transducer being suitable for the simultaneous production of a large number of transducers.

[0048] The transducers emit for example in a carrier frequency range of 20 kHz-150 kHz, and more generally any frequency range above the audible range.

[0049] The transducers may have a dimension between 50 qm and 5000 qm, in particular between 150 qm and 1000 qm. Distribution of transducers

[0050] The spacing between the transducers can be between 10 qm and 10000 qm, better between 100 qm and 500 qm. This spacing is sufficient to have an interface that is sufficiently rigid to be manufactured.

[0051] In one example, the transducer sets are arranged in a generally nested distribution in order of carrier frequency height. For example, the transducers are arranged in a generally concentric arrangement in order of active membrane size, with the set having the smallest active membrane, i.e., emitting at the highest frequency, being, for example, located in the center. Other arrangements are possible, for example, alternating transducer sets of different carrier frequencies in one or two directions, or transducer sets located at different levels, or pointing in different directions. Use

[0052] The interface according to the invention can be used in applications such as virtual reality, mixed reality or augmented reality headsets and glasses. Method

[0053] The invention also relates to a method for generating at least one or more tactile and / or sound perceptions located remotely using a multimodal interface as defined previously, comprising the modulation, by means of a control circuit, of the control signals sent to the transducers in order to: • generate with the ultrasonic waves emitted from the actuated transducers an acoustic pressure detectable by touch in a first focal zone, and / or • generate with the ultrasonic waves emitted by actuated transducers an acoustic pressure detectable by sound in a second focal zone.

[0054] The method may comprise the steps of: - Determine the spatial position(s) where tactile and / or sound perception is generated, - Determine the transducers to be actuated and calculate the phase shift to be applied to these transducers in order to generate the desired tactile and / or sound perception(s).

[0055] The first focal zone and the second focal zone may be partly superimposed, in particular merged. Alternatively, the first focal zone and the second focal zone are distinct from one another. Brief description of the drawings

[0056] The invention may be better understood by reading the detailed description which follows, non-limiting examples of its implementation, and by examining the appended drawings, in which:

[0057] [Fig. 1 A] [Fig. 1 A] represents in a partial and schematic manner an example of a “mid air” type haptic and sound interface according to the invention,

[0058] [Fig.lB] [Fig.lB] schematically illustrates the principle of focusing ultrasonic waves by playing on the phase shift,

[0059] [Fig.2] [Fig.2] is a partial and schematic top view of an example of ultrasonic transducer,

[0060] [Fig.3] [Fig.3] partially and schematically represents an example of a rea lization of a transducer matrix comprising transducers of different sizes,

[0061] [Fig.4a] [Fig.4a] partially and schematically represents an example of a rea lization of a set of transducer matrices,

[0062] [Fig.4b] [Fig.4b] represents in a partial and schematic manner another example of production of a set of transducer matrices,

[0063] [Fig.4c] [Fig.4c] represents in a partial and schematic manner another example of the realization of a set of transducer matrices,

[0064] [Fig.5] [Fig.5] is a partial and schematic section of an exemplary embodiment of an ultrasonic transducer of the PMUT type,

[0065] [Fig.6] [Fig.6] is a block diagram illustrating steps of an exemplary method of manufacturing a plurality of PMUT type ultrasonic transducers,

[0066] [Fig.7] [Fig.7] is a partial and schematic section illustrating the second step of [Fig.6],

[0067] [Fig.8] [Fig.8] is a partial and schematic section of the plurality of PMUT type transducers after the third step of [Fig.6],

[0068] [Fig.9] [Fig.9] is a partial and schematic section of the plurality of PMUT type transducers of [Fig.6] before die cutting,

[0069] [Fig. 10] [Fig. 10] is a partial and schematic section illustrating an example of electrical connection of the transducer of [Fig.5],

[0070] [Fig. 11] [Fig. 11] is a block diagram illustrating an example of operation of the haptic interface according to the invention,

[0071] [Fig. 12] [Fig. 12] illustrates measurements of the sound pressure generated by a PMUT transducer working at a frequency of 100 kHz and being supplied with a voltage of 5 V, and

[0072] [Fig. 13] [Fig. 13] illustrates measurements of the sound pressure generated by an array of 64 PMUT transducers working at a frequency of 100 kHz. Detailed description

[0073] [Fig.1A] schematically illustrates an example of a haptic and sound interface 1 according to the invention.

[0074] The interface 1 comprises a plurality of ultrasonic transducers 2, for example carried by the same support 4, and a control circuit 3.

[0075] The plurality of transducers 2 comprises a first set 25 of transducers emitting at a first ultrasonic carrier frequency and a second set 26 of transducers emitting at a second ultrasonic carrier frequency, different from the first. Alternatively, and preferably, the transmission carrier frequencies of the sets 25 and 26 are the same.

[0076] The assemblies 25 and 26 may be distinct, as illustrated in [Fig.lA]. Alternatively, they are merged or one of the assemblies 25 or 26 is included in the other assembly.

[0077] The control circuit 3 is configured to modulate the signals 30 sent to the transducers 2 in order to generate with the ultrasonic waves emitted by the first set of transducers a tactilely detectable acoustic pressure on a surface S, defined for example by the palm and / or fingers of a hand, in a first focal zone 10, and with the ultrasonic waves emitted by the second set of transducers an acoustic pressure detectable audibly by an auditory receiver R, defined for example by an ear, in a second focal zone 11. [Fig.lA] is schematic, and in practice, this second focal zone 11 is not on the ear but in the space around the user, ideally close to the ear to ensure that one can hear despite the limited acoustic pressures. Each focal zone has spatial characteristics depending in particular on the carrier frequency of the set of transducers at the origin of the corresponding acoustic pressure.

[0078] The focal zones 10 and 11 may be located at distinct locations in space or may overlap at least partially. They may or may not be of different sizes.

[0079] The tactilely detectable acoustic pressures are generated by the transducers according to a principle known as “acoustic electronic focusing”, known from the prior art, illustrated schematically in [Fig. 1B].

[0080] [Fig.1B] illustrates the concentration of the ultrasonic waves 20 emitted by the transducers 2 of the same set of transducers in a predefined focal zone 10. The control circuit 3 sends, in a manner known per se, to the transducers 2 complex alternating signals 30 in order to introduce phase shifts between the different ultrasonic waves emitted by the actuated transducers 2, thus generating the desired wavefront shape, this wavefront shape resulting in an increase in the acoustic pressure in the focal zone 10.

[0081] The sonically detectable acoustic pressures are generated by the transducers also following the principle of acoustic electronic focusing, as described in the article by Dejeager et al mentioned in the introduction.

[0082] In the example considered, the interface 1 further comprises a detection system 5 configured to detect the position of the surface S to be tactilely stimulated and that of the receiver R to be acoustically stimulated. The detection system 5 is configured to transmit corresponding location data 50 to the control circuit 3. The interface 1 is called “mid-air” type because the surface S to be tactilely stimulated and the receiver R to be acoustically stimulated are located at a distance from the transducers 2, and the focal zones 10 and 11 are located in the air at a distance from the transducers, being visually invisible to the user.

[0083] [Fig. 2] shows an example of a transducer 2 carried by a support 4. The transducer 2 comprises, for example, a piezoelectric actuator 21 and an active membrane 22 set into vibration by the actuator 21.

[0084] In the example considered, the active membrane 22 is circular in shape. In In other embodiments, the active membrane 22 is of non-circular shape, for example polygonal, in particular square, rectangle, or any other suitable shape, 2D or 3D, the membrane being able to be of convex or concave shape. The radius of the piezoelectric actuator 21 is for example of the order of 50% of the radius of the active membrane 21, this ratio being advantageous for good deformation of the membrane, as described in the article by Casset, F., et al. "Piezoelectric membrane actuator design." (2011 12th Intl. Conf. on Thermal, Mechanical & Multi-Physics Simulation and Experiments in Microelectronics and Microsystems. IEEE, 2011).

[0085] Within each set of transducers, the latter are identical and therefore emit at the same carrier frequency. From one set to another, the transducers 2 differ for example in their dimension, each dimension corresponding to a respective carrier frequency. The active membrane 22 of the transducers 2 varies for example in thickness and / or radius, preferably in radius, from one set to another.

[0086] The transducers of the different assemblies of the interface according to the invention can be arranged within one or more matrices 40. By “matrix”, we mean a single-piece structure carrying several transducers, identical or not. A matrix can comprise transducers which have been produced simultaneously, as detailed below.

[0087] [Fig. 3] shows a matrix 40 of ultrasonic transducers 2 comprising three sets 25, 26 and 27 of transducers of different respective sizes, the transducers 2 being arranged on the support 4 following for example a concentric distribution, as illustrated. For example, the set 25 corresponds to that comprising the transducers 2 of smaller size, arranged in the center of the matrix, the set 26 to that comprising the transducers 2 of intermediate size, and the set 27 to that comprising the transducers 2 of larger size, distributed on the periphery of the matrix.

[0088] The active membranes 22 of the transducers 2 of the assemblies 25, 26 and 27 have, for example, radii of 1000, 1600 and 2200 micrometers, respectively. The carrier frequency f corresponding to a given membrane size can be estimated using the following equation, taken from the article by Nguyen, MD, et al. "Optimized electrode coverage of membrane actuators based on epitaxial PZT thin films." (Smart materials and structures 22.8 (2013): 085013.):

[0089] r_ I e lîrr2 y 12 / ^1-t)

[0090] with £ and v the Young's modulus and Poisson's ratio of the membrane, respectively, P its average density,? its thickness and r its radius. is the resonance eigenvalue of the membrane with n the resonance mode.

[0091] In the example considered, the carrier frequency of the transducers 2 of the sets 25, 26 and 27 is thus approximately 107 kHz, 44 kHz and 22 kHz, respectively. Depending on these frequencies, the haptic effect can be generated at a distance of the order of 8 cm to 1 m.

[0092] The transducers of different sets can be arranged within the same matrix 40 in various ways, for example in a generally concentric manner as illustrated in [Fig. 3], or else mixed randomly or by respecting other rules for arranging the transducers relative to each other.

[0093] In other embodiments, as illustrated for example in Figures 4a, 4b and 4c, the assemblies are arranged on respective distinct matrices 40 which are for example grouped together, the matrices 40 being for example assembled in the same plane. The matrices 40 may be of different sizes and shapes, such as in [Fig.4a], or of similar size such as in [Fig.4b]. The membranes 22 of the transducers 2 of each matrix 40 may differ in thickness, as illustrated in [Fig.4c]. Preferably, the membranes 22 of the transducers 2 of the matrices 40 are identical, and in particular the membranes 22 of the transducers 2 of the assemblies 25, 26 and 27 are identical. This makes it possible to limit the number of membranes necessary to produce haptic and / or sound effects.

[0094] [Fig. 5] shows an example of an embodiment of a transducer 2 of the interface 1. In the example considered, the transducer 2 is of the micro-machined piezoelectric type (PMUT) and comprises, as described previously, an active membrane 22 fixed on a rigid support 4 and a piezoelectric actuator 21 arranged on the membrane 22.

[0095] The rigid support 4 is for example made of silicon. An insulating layer 41, for example made of silicon oxide, can be added between the support 4 and the membrane 22. The membrane 22 is fixed to the support only by its periphery, its central part being free to bend.

[0096] The membrane 22 is formed from one or more superimposed constituent layers and has a total thickness for example between 0.5 and 10 μm. In the example considered, the membrane 22 is composed of two superimposed layers 220 and 221. The lower layer 220 is for example made of polysilicon and is 4 μm thick. The upper layer 221 is for example made of silicon oxide and is 1.9 μm thick. Other materials can be used for the membrane 22, in particular based on monocrystalline silicon, or silicon nitride.

[0097] The piezoelectric actuator 21 comprises, for example, four superimposed layers 210, 211, 212 and 213. The layer 210 is in contact with the upper layer 221 of the membrane 22. The layer 210 is, for example, made of platinum and constitutes the lower electrode of the actuator 21. The upper electrode of the actuator comprises in this for example a layer 212, for example made of ruthenium, and a conductive layer 213, for example made of gold. The layer 211 which is located between the two electrodes is made of piezoelectric or ferroelectric material, for example of the lead zirconate titano type (PZT). It can also be made of aluminum nitride (AIN), zinc oxide (ZnO) or any other suitable piezoelectric or ferroelectric material.

[0098] To obtain the PMUT transducer illustrated in [Fig.5], a manufacturing method can be implemented comprising the steps shown in [Fig.6], and making it possible to produce a large number of transducers simultaneously.

[0099] In step 71, one or more layers, for example 4 μm thick, for example made of polysilicon and silicon oxide, are deposited on the upper face of a rigid substrate 4, for example made of silicon, in order to form the active membranes 22 of the transducers. An insulating layer 41 may be deposited between the substrate 4 and the first layer of the membrane beforehand.

[0100] In step 72, the materials that will form the piezoelectric actuators 21 are successively deposited in a thin layer. For example, a 100 nm layer of platinum 210 is first deposited to form the lower electrode, then it is covered with a 2 μm layer 211 of a PZT type piezoelectric material, which is subsequently itself covered by a 100 nm thin layer of ruthenium 212. At the end of step 72 and as illustrated in [Fig. 7], a continuous stack of the layers previously described is obtained, namely from bottom to top: the support 4, the insulating layer 41, the layers 220 and 221 forming the membrane 22, and the layers 210, 211 and 212 forming the piezoelectric actuator 21.

[0101] In step 73, and as illustrated in [Fig. 8], the plurality of transducers are then formed on the support 4 by applying photolithography masks and by etching the layers 210, 211 and 212 constituting the piezoelectric actuator. This step may further comprise the application of an insulating passivation layer 214, for example made of silicon oxide, and of a conductive layer 213, for example made of gold, on at least a portion of the layer 212.

[0102] In step 74, the lower face of the support 4 and the insulating layer 41 are cut, for example via the application of a mask then by etching, so as to expose the lower face of the central part of the active membrane 22 of each transducer as illustrated in [Fig.9].

[0103] It is thus possible to produce a plurality of transducers simultaneously on the same support in a simple manner. In step 75, the support can then be cut in order to obtain matrices 40 of transducers of the desired size. The size and thickness of the membranes can be varied to obtain transducers of different frequencies.

[0104] In step 76, each transducer is electrically connected to an electronic control, for example, through through connections 7.

[0105] To electrically connect the transducers thus obtained to their control electronics, flexible connectors can be connected to each of the transducers.

[0106] The matrices 40 thus obtained can then be integrated into a housing and the flexible connectors connected to the control electronics. Alternatively and as illustrated in [Fig. 10], through-connections 7 can be used to bring electrical contacts to the lower face of the support 4. The transducer matrices 40 can then be directly integrated onto the control electronics.

[0107] When a voltage difference is applied between the electrodes 210 and 213, the piezoelectric layer 211 can deform under the action of the generated electric field, inducing a deformation of the active membrane 22 and the emission of an acoustic wave. Conversely, the transducer 2 thus connected can act as an acoustic wave receiver, for example as a system for detecting the surface S on which the haptic effect is to be generated and / or the receiver R at which the sound effect is to be generated. In this case, the reception of an acoustic wave deforms the layer 211 and therefore the membrane 22, causing a variation in the electric field which can be translated by an electrical signal on the electrodes, measured using the electrical connections 7.

[0108] A haptic and sound interface 1 according to the invention, coupled with a detection system 5, can operate according to the steps described in [Fig. 11].

[0109] In step 81, the interface 1 is for example on standby, in the absence of a user in the detection field of the detection system 5. In step 82, the detection system 5, for example produced with a part of the transducers 2 or with any other suitable detection system, for example a camera, for example optical, detects the presence of a surface S and / or a receiver R of a user in the detection field, and locates the place where the haptic and / or sound effect(s) must be generated. In step 83, the control circuit 3 calculates, from algorithms known to those skilled in the art, the phase shift to be applied to the transducers and sends the appropriate control signals 30 to actuate at least a part of the transducers 2 so as to generate the desired haptic and / or sound effects.In step 84, the transducers emit ultrasonic waves at different carrier frequencies, depending on the actuated assemblies, making it possible to generate one or more haptic and / or sound effects in one or more focal zones. In step 85, the user withdraws from the detection field and the interface 1 returns to standby.

[0110] The working frequencies of the transducers 2 used for the haptic and sound effects may be different or identical. If the frequencies are the same, the matrix 40 comprising the transducers 2 used for the haptic and sound effects may be monolithic and manufactured in one go, for example according to the method described in [Fig.6]. If the frequencies are different, the matrix 40 can also be produced monolithically using the same production method by varying the radius of the membranes 22 of the transducers 2. A first matrix 40 comprising the transducers 2 used for the haptic effects and a second matrix 40 comprising the transducers used for the sound effects can also be assembled.

[0111] The dimensioning of the matrix(s) 40 of transducers 2 depends on the desired haptic and / or sound effect(s).

[0112] The unit acoustic pressure P generated by a transducer can be calculated from the surface area Sm of its membrane, its carrier frequency / and the distance d at which it is generated, using the following equation for acoustic pressure from a plane piston:

[0113] JÏ.~.pSme,f2 7 ~ d

[0114] With P the average density of the membrane and e the amplitude of the vibration.

[0115] In an example of matrix 40, the ultrasonic transducers 2 used are of the PMUT type and work at a frequency of 100 kHz. But other types of transducers can be used indifferently, for example electromagnetic actuators. The radius of the membrane 22 of the PMUT transducers 2 considered is of the order of 400 pm and the gap between the membranes 22 of the transducers 2 is of the order of 300 pm, which is a sufficient gap to allow solidity of the matrix 40. For a given frequency, the radius of a transducer 2 is a function of the stiffness of its membrane 22, linked to its thickness and its constituent materials.

[0116] A PMUT 2 transducer working at 100 kHz powered by a voltage of 5V makes it possible to generate an acoustic pressure of the order of 0.15 Pa at a distance of 30 cm, according to the measurements illustrated in [Fig. 12]. It is possible to assume an acoustic pressure increasing linearly with the voltage up to a maximum voltage of 48 V, corresponding to 1.44 Pa.

[0117] It is known to those skilled in the art that the acoustic pressure threshold allowing a haptic effect to be felt is approximately 200 Pa. By linearly adding the acoustic pressures generated for a voltage of 48V, it results that 139 transducers are required to obtain a haptic effect at 30 cm.

[0118] In this example, in order to generate a haptic effect that is tactilely perceptible at 30 cm, the matrix 40 therefore has a minimum dimension of the order of 1.5*1.5 cm2.

[0119] It is known to those skilled in the art that the acoustic perception threshold for feeling a sound effect is approximately 120 dB.

[0120] [Fig. 13] shows that, in the example considered, 64 PMUT 2 transducers working at 100 kHz make it possible to generate a pressure of 30 dB at 8 cm. In addition- linearly giving the generated acoustic pressures, it results that 256 transducers are needed to generate a sound effect perceptible at 8 cm, which corresponds to a matrix of minimum dimension of the order of 2*2 cm2.

[0121] Thus, in the example considered, the multimodal interface 1 is made up of at least 395 (139+256) transducers 2 to simultaneously generate a haptic effect and a sound effect.

[0122] However, it is also possible to generate the haptic and sound effects sequentially. In this case, a multimodal interface 1 of at least 256 transducers 2 is sufficient to generate both effects.

[0123] It is possible to increase the number of transducers 2 of the interface 1 to increase the effect, the number of simultaneous effects, and / or increase the working distance.

[0124] The haptic and sound interface 1 can be integrated into a virtual, augmented or mixed reality headset which generates for example a scene, or a virtual image such as a ball. The user can tap this ball with his hand and the interface 1 can send haptic information of contact with the ball. Simultaneously or sequentially, with an imperceptible lag for the user of the order of several tens of milliseconds, for example 100 ms, the interface 1 can send sound information to the user who hears a sound in the direction of the ball, giving him the impression that he hears the noise of the ball being hit.

[0125] Of course, the invention is not limited to the examples which have just been described.

[0126] The transducers may be produced in a manner other than by the manufacturing method described above. The active membranes are, for example, produced on a glass support or on a flexible sheet of polymer. The piezoelectric actuator may be located in the center of the membrane or not, in the form of a disc or a ring or any other shape, and may be of various sizes relative to the size of the membrane. There may be several piezoelectric actuators on the same membrane, for example one in its center and one on the periphery. The transducers may be deposited in a thin layer or transferred directly onto the membrane. As described above, the transducers of different membrane sizes may be arranged on the support in any distribution.

[0127] The ultrasonic waves in the examples considered propagate in air, but any type of medium can be considered, for example a liquid.

[0128] Haptic effects may be generated to give a user the impression of touching different textures.

[0129] The haptic and sound interface 1 can be connected to one or more systems generating a visual effect, for example at least one screen, mirror or hologram.

Claims

Claims

1. Haptic multimodal interface, comprising: - a control circuit (3), - a matrix comprising a plurality of ultrasonic transducers (2) connected to said circuit, the control circuit being configured to modulate the signals (30) sent to the transducers (2) in order to: - generate with the ultrasonic waves emitted by at least a portion of the transducers an acoustic pressure detectable by touch in at least a first focal zone (10), and / or - generate with the ultrasonic waves emitted by at least a portion of the transducers an acoustic pressure detectable by sound in at least a second focal zone (11).

2. Multimodal interface according to claim 1, comprising at least one set of transducers arranged to generate haptic effects and sound effects.

3. Multimodal interface according to one of claims 1 and 2, comprising at least two sets of ultrasonic transducers, a first set of transducers being arranged with the control circuit to generate haptic effects and a second set of transducers not included in the first being arranged to generate with the control circuit sound effects simultaneously and / or successively to the haptic effects generated by the first set.

4. A multimodal interface according to any preceding claim, comprising at least two sets of ultrasonic transducers, the transducers of a first set and those of a second set having identical active membranes (22).

5. Multimodal interface according to any one of the preceding claims, comprising at least two sets of ultrasonic transducers, the transducers of a first set and those of a second set being carried by the same support (4).

6. Multimodal interface according to any one of the preceding claims, comprising at least one detection system (5) configured to detect the position relative to the transducers of at least one surface (S) to be tactilely stimulated and / or of at least one auditory receptor to be sound-stimulated, the control circuit (3) being arranged to control the transducers and in particular the position of the first and second focal zones depending on the position of the surface and / or the auditory receptor.

7. Multimodal interface according to any one of the preceding claims, each transducer (2) being of the piezoelectric, ferroelectric, electromagnetic, thermal or ceramic piezoelectric type, preferably of the piezoelectric type, in particular of the micro-machined piezoelectric type (PMUT).

8. Method for generating one or more remotely located tactile and / or sound perceptions using a multimodal interface as defined in any one of claims 1 to 7, comprising the modulation, by means of a control circuit, of the control signals sent to the transducers in order to: • generate with the ultrasonic waves emitted from the actuated transducers a tactilely detectable acoustic pressure in a first focal zone, and / or • generate with the ultrasonic waves emitted by actuated transducers an audibly detectable acoustic pressure in a second focal zone.

9. Method according to the preceding claim, comprising the steps of: - Determining the spatial position(s) where the tactile and / or sound perception is to be generated, - Determining the transducers to be actuated and calculating the phase shift to be applied to these transducers in order to generate the desired tactile and / or sound perception(s).

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