Classifications

• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
  • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
  • G06F3/043—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using propagating acoustic waves
  • G06F3/0436—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using propagating acoustic waves in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
  • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06F—ELECTRIC DIGITAL DATA PROCESSING
  • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
  • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
  • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
  • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
  • G06F3/043—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using propagating acoustic waves
  • G06F3/0433—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using propagating acoustic waves in which the acoustic waves are either generated by a movable member and propagated within a surface layer or propagated within a surface layer and captured by a movable member

Definitions

• the present invention relates to a device for locating a locally deforming contact on a deformable tactile surface of an object. It also relates to a method implemented by this device.
• touch-surface objects are known, including mobile phones or other portable digital personal assistance devices. Their touch interface is usually a flat and rectangular screen with which a user can interact with a stylus or a finger. It will be noted, however, that the invention applies more generally to any type of object having a deformable tactile surface that is not necessarily flat or rectangular contour. It thus advantageously applies to communicating objects with a tactile and intuitive human machine interface, in particular robots, having a three-dimensional deformable shell attached to a rigid support in a limited number of fixing points.
• tactile surface or “deformable” shell is meant a two-dimensional or three-dimensional surface, capable of changing its shape in the sense of the static and dynamic elasticity of the materials when it is subjected to a static or dynamic stress such as a touch, a force contact, a mechanical pulse or a shock, and may have resonant vibrations when it is excited by elastic mechanical waves, including pulses, so as to deform in bending, even submillimeter non-perceptible to the eye bare.
• Plastic, glass or metal shells are suitable.
• Each of the known tactile surface objects comprises a device for locating touches or impacts using one or more detection techniques.
• a strong trend towards reducing manufacturing cost and reducing clutter is to retain only the simplest technologies using a limited number of sensors.
• the invention thus relates more precisely to a localization device implementing a technology for detecting the propagation of elastic mechanical waves in a tactile surface, in particular using detectors of the piezoelectric transducer type.
• a first solution is disclosed in the French patent applications published under the numbers FR 2 725 513, FR 2 787 608 and FR 2 81 1 107. It is based on the measurement of a transit time difference from a wave packet to a plurality of piezoelectric detectors and on the deterministic calculation, using a pre-established mathematical formula, of the position of a transmitting source of the wave packet. This wave packet is more precisely emitted by an acoustic source coming into contact with the tactile surface. In general, it is thus possible to locate a finger or stylus impact, since it is then emitting a pulse.
• this technology it is not possible to detect the persistence of a touch after the impact, or the displacement of the acoustic source on the touch surface, except to predict that the acoustic source regularly emits wave packets : it is then limited to applications using a stylus with repeated emission of wave packets.
• this technology is well suited to tactile surfaces in the form of isotropic flat plates, but poorly adapted to any three-dimensional shells that do not allow a deterministic calculation of the position of the acoustic source via a mathematical formula pre- established.
• this technology does not detect a static stress or the force of a touch (caress, unfriendly interaction, etc.).
• a second solution is disclosed in the French patent application published under the number FR 2 841 022. It is based on a recognition of the position of an impact learning.
• the method implemented cross-correlates at least one measured acoustic signal resulting from the detection of an acoustic wave generated by an impact on the tactile surface of the object and a reference set called "set of signatures" consisting of prerecorded impulse acoustic responses, each relating to a predefined position that one wishes to associate with a function and recognize when an impact is carried on this position.
• set of signatures consisting of prerecorded impulse acoustic responses, each relating to a predefined position that one wishes to associate with a function and recognize when an impact is carried on this position.
• the invention relates to this type of solution. It thus applies to a device for locating a locally deforming contact on a deformable tactile surface of an object, comprising:
• At least one emission transducer designed to emit elastic mechanical waves propagating in the deformable tactile surface of the object
• At least one reception transducer designed to capture elastic mechanical waves propagating in the deformable tactile surface of the object
• an electronic central unit connected to the transmit and receive transducers, programmed to analyze a signal picked up by the reception transducer and to deduce the presence or absence of a touch.
• Such a device is described in the international patent application published under the number WO 2008/142345. It more precisely allows a reliable location of a touch by propagating waves having a plurality of frequency components corresponding to vibratory eigenfrequencies of the object.
• the propagation of these waves for a certain time in the tactile surface makes it possible to materialize vibration patterns at different wavelengths, in particular resonance figures of bending modes. These have the characteristic of being more strongly disturbed than the resonant patterns of vibration modes in the plane of the tactile surface of the object so that the damping or absorption generated by a finger brought into contact with the tactile surface, even in the case where the latter is thick, varies measurably from one mode to the other and from one contact position to another. It is thus possible to locate a touch by a learning method, as soon as a sufficient number of resonance figures is materialized on the surface of the object.
• This method offers the advantage of requiring only a small number of transmit and / or receive transducers and allows operation on three-dimensional shells of any shape with a measurement rate of up to several tens of locations per second.
• this device requires a touch having a sufficient contact surface with the touch surface to achieve a detectable damping. It is thus poorly suited to the detection of near-point touches such as those generated by the tip of a stylus. It is also well suited for thin hulls, but not suitable for thick hulls. It may thus be desired to provide a device for locating a locally deforming contact on a deformable tactile surface of an object that makes it possible to overcome at least some of the aforementioned problems and constraints.
• the subject of the invention is therefore a device for locating a locally deforming contact on a deformable tactile surface of an object, comprising:
• At least one emission transducer designed to emit elastic mechanical waves propagating in the deformable tactile surface of the object
• At least one reception transducer designed to capture elastic mechanical waves propagating in the deformable tactile surface of the object
• the electronic central unit is programmed to:
• the invention proceeds from a very different approach from conventional approaches using the propagation of elastic mechanical waves, such as that recommended in the document WO 2008/142345. Indeed, it is not based on the damping of natural modes of vibrations generated by a touch but on the measurement of a shift in frequency of these eigen modes due to the presence of this touch.
• a contact of touch or long impact type causes an increase the natural frequencies of vibration of a tactile surface, provided that it sufficiently blocks the surface in resonance.
• the frequency shift of one or more eigen modes of vibration of the touch surface of the object is discriminant depending on the position of the contact. It also appears that this frequency shift is sensitive to the force of the contact since the tactile surface of the object is deformable and makes it possible to distinguish a caress from an unfriendly touch due to excessive pressure. for example. It is also noticeable when the contact is almost punctual, like a touch from the tip of a stylus.
• a device may comprise several rigid attachment zones of the deformable tactile surface on the object, these zones forming resonant vibration nodes of the tactile surface, and the transmitting and receiving transducers may be located in these areas.
• a device may comprise at least one pair of transmit and receive transducers and each transducer of the same pair may be located in a zone diametrically opposite to that of the other transducer of this pair. same pair in the deformable touch surface.
• a device may comprise several pairs of transmit and receive transducers, each pair being disposed at the ends of a characteristic axis of the deformable tactile surface, in particular an axis of symmetry of the tactile surface. .
• the emission transducers are directional emission of elastic mechanical waves and oriented to present a directivity diagram of maximum intensity in the direction of the other transducer of the same pair.
• each transducer being designed to indifferently emit or receive elastic mechanical waves
• the electronic central unit is programmed to select one of the two transducers of the same pair as a transmission transducer as a function of a presumed approximate location of the contact to be detected.
• the transducers are integral with spacers for fixing the deformable tactile surface on a rigid chassis, so as to generate vibrations in the spacers transmitted to the deformable tactile surface when these vibrations originate from emission transducers or transmitted to reception transducers when they come from the deformable tactile surface.
• the electronic central unit is furthermore programmed, in response to the detection of the frequency shift due to the presence of the locally deforming contact, exciting at least one transmission transducer with the aid of an electrical signal. of vibroacoustic wave frequency generator validation related to the frequency offset detected and of amplitude substantially greater than the other elastic mechanical waves emitted in the tactile surface for the location of the contact.
• the subject of the invention is also a communicating object comprising a shell with a deformable tactile surface and a device as defined above, in which the deformable tactile surface of the shell comprises at least one zone that is locally delimited and functionalized with specific deformability, in particular with monostability. or asymmetrical bistability.
• the invention also relates to a method for locating a locally deforming contact on a deformable tactile surface of an object, comprising the following steps:
• the locating step comprises analyzing a frequency offset, due to the presence of the locally deforming contact, of at least one eigenmode of a resonant vibration of the tactile surface generated by the propagation of the waves emitted in this touch surface.
• the monitoring step comprises transmitting pulse-width pulsed elastic mechanical waves in a predetermined range of frequencies including at least one fundamental resonant vibration fundamental frequency of the non-contact touching surface and twice that of frequency.
• FIG. 1 schematically represents a front view of a device for locating a locally deforming contact on a deformable tactile surface of an object, according to a first embodiment of the invention
• FIG. 2 schematically represents a partial front view of a device for locating a locally deforming contact on a surface; deformable touch of an object, according to a second embodiment of the invention
• FIG. 3A shows schematically and in section a zone with asymmetric bistability, locally delimited and functionalized in the tactile surface illustrated in FIG. 2,
• FIGS. 3B and 3C schematically and graphically illustrate a deformation and the corresponding force-displacement curve of the asymmetric bistability zone of FIG. 3A
• FIGS. 4, 5 and 6 show schematically and in section the tactile surface illustrated in FIG. 2, according to three variant embodiments.
• FIG. 7 illustrates the successive main steps of a method of locating a locally deforming contact on a deformable tactile surface of an object, according to one embodiment of the invention.
• the device 10 for locating a locally deforming contact on a deformable tactile surface of an object comprises an electronic central unit 12 and an object 14, for example of the interactive tablet type.
• the interactive tablet 14 comprises a frame 16 and a touch surface 18 held by the frame on at least a portion of its periphery.
• the touch surface 18 is for example in the form of a rectangular thin plate of metal, glass or plastic, vibrating when elastic mechanical waves are emitted in its thickness. It is considered to be deformable in the sense that, as indicated previously, it exhibits resonant vibrations when it is excited by elastic mechanical waves, in particular pulses, so as to deform in bending, even in a submillimetric manner which is not perceptible at all. naked eye in the case of glass for example.
• piezoelectric transducers E1, E2, R1 and R2 are fixed on the inside face of the touch plate 18, that is to say the one that is not accessible to the touch and facing the 16.
• they can be glued to the plate 18 by means of a conductive epoxy glue or cyanoacrylate. They can also be secured to specific means for fixing the touch plate 18 on a rigid support.
• piezoelectric transducers are, for example, ferroelectric ceramic PZT type transducers. They include:
• two emission transducers E1 and E2 capable of transmitting elastic mechanical waves (ie acoustic waves in the broad sense) in bending modes, such as antisymmetric Lamb waves, such that they propagate in the touch plate 18,
• a first pair of transmit / receive consists of the transducers E1 and R1 disposed at both ends of a first characteristic axis D1 of the touch plate 18.
• This axis D1 is an axis of symmetry of the touch plate 18: it is more precisely its longitudinal median axis.
• the second pair of transmission / reception consists of the transducers E2 and R2 disposed at both ends of a second characteristic axis D2 of the touch plate 18, perpendicular to the axis D1.
• This axis D2 is another axis of symmetry of the touch plate 18: it is more precisely its transverse median axis.
• the two ends of the axis D1 are also rigid attachment zones of the deformable tactile plate 18 on a rigid support of the object 14.
• the emitter transducer E1 is with directional emission of elastic mechanical waves: it is more precisely of shape and orientation chosen to present a directivity diagram of maximum intensity in the direction of the axis D1, that is to say in the direction of the transducer reception R1.
• pulse waves when pulse waves are emitted by the emission transducer E1, in the direction of the axis D1, they cause a resonant vibration of the touch plate 18 at at least one fundamental natural frequency, linked to its length in the absence of contact on the plate, knowing that the rigid attachment zones, that is to say the areas where are arranged transducers E1 and R1, form resonant vibration nodes at all eigenfrequencies of the touch plate 18 in this direction D1.
• the two ends of the axis D2 are also rigid attachment areas of the deformable tactile plate 18 on a rigid support of the object 14.
• the emitter transducer E2 is a directional emulsion of elastic mechanical waves and is of a shape and orientation chosen to present a directivity diagram of maximum intensity in the direction of the axis D2, that is to say say towards the receiving transducer R2.
• pulse waves when pulse waves are emitted by the emission transducer E2, in the direction of the axis D2, they cause a resonant vibration of the touch plate 18 at at least a fundamental natural frequency, linked to its width in the absence of contact, knowing that the rigid attachment zones, that is to say the areas where the transducers are arranged E2 and R2 form resonant vibration nodes at all eigenfrequencies of the touch plate 18 in this direction D2.
• the transducers E1, E2, R1 and R2 are connected to the electronic central unit 12 by at least one connection 20, wire or radio.
• the electronic central unit 12 is programmed to:
• connection (s) 20 to the transducers E1, E2, R1 and R2 may or may be constituted (s) including coaxial cables of audio type or any other shielded connection.
• the electronic central unit 12 comprises an emitter 22 programmed to control the emission of pulsating elastic mechanical waves in the direction D1 from the emitting transducer E1, these waves generating a resonant vibration of the flexion of the touch plate 18 according to a plurality of eigen modes (ie a fundamental mode and several harmonic modes). It furthermore comprises a receiver 24 programmed to pick up a signal characteristic of the resonant vibration of the tactile surface from the transducer R1, the spectrum of this signal picked up having amplitude peaks at the frequencies of the eigenmodes of the plate in the direction D1.
• an emitter 22 programmed to control the emission of pulsating elastic mechanical waves in the direction D1 from the emitting transducer E1, these waves generating a resonant vibration of the flexion of the touch plate 18 according to a plurality of eigen modes (ie a fundamental mode and several harmonic modes).
• a receiver 24 programmed to pick up a signal characteristic of the resonant vibration of the tactile surface from the transduc
• the receiver 24 of the electronic central unit 12 is therefore connected to a spectral analysis module 26 programmed to detect the frequency peaks of the signal picked up, in particular by calculating a fast Fourier transform.
• the eigen modes detected are characteristic of its length.
• the detected eigen modes are shifted with respect to the eigen modes detectable in FIG. the absence of contact and these offsets are characteristic of the abscissa x of the contact.
• a one-dimensional analogy can be made with the vibration of a guitar string stretched between two ends of fixation and excited by pinching, which generates, in the portion of vibrating string opposite the opening of the box of resonance, different sound resonance frequencies depending on where it is blocked or not on its length.
• the use of a stylus or a finger to apply a locally deforming contact on the deformable touch plate 18 is comparable to the insertion of an additional fixed point generating a significant shift of the resonance frequencies depending on the position and the nature of the local blocking, total or partial, of the deformable tactile plate 18.
• the transmitter 22 is programmed to control the emission of pulsed elastic mechanical waves in the direction D2 from the emitting transducer E2, these waves generating a resonant vibration of flexion of the touch plate 18 according to a plurality of eigen modes. (ie a fundamental mode and several harmonic modes).
• the receiver 24 is furthermore programmed to pick up a signal characteristic of the resonant vibration of the touch plate from the transducer R2, the spectrum of this signal picked up having amplitude peaks at the frequencies of the eigen modes of the plate in the direction D2. .
• the eigen modes detected are characteristic of its width.
• the detected eigen modes are shifted with respect to the eigen modes detected in FIG. the absence of contact and these offsets are characteristic of the ordinate y of the contact.
• the two reception transducers R1 and R2 can be connected to two analog / digital converters, themselves connected to the integral parts or the receiver 24.
• the analog / digital converters and the receiver 24 are able to perform a sampling of the signals. captured on at least 8 bits, preferably on 10 bits, or even 12 bits or more at a rate of at least 200 kHz.
• the electronic central unit 12 comprises an analysis module 28 programmed to compare the eigen modes detected with eigen modes without reference contact in the direction, deduce the respective offsets of these detected eigen modes, then estimate the position of the contact as a function of these offsets.
• This estimate can be made using mathematical formulas pre-established, for example deduced from an interpolation law, stored in memory 30 or by comparison with offsets previously measured for a set of predetermined positions and stored in memory 30 in the form of reference vectors or a correspondence table between frequency offsets and contact positions.
• the simultaneous knowledge of the fundamental and possibly harmonic frequency offsets along the two axes D1 and D2 thus makes it possible to go back to the position of the (x, y) of the contact.
• the emitting transducers E1 and E2 are advantageously excited alternately along the axes D1 and D2 to limit the confusions between the eigenfrequencies of the two directions.
• the receiving transducers R1 and R2 can continuously pick up the signals along the axis D1 and the axis D2.
• a location (x, y) of this contact which can for example be displayed on a screen (not shown ).
• waves can be emitted regularly by the emission transducers E1 and E2
• a succession of contacts can be detected on the touch plate 18, forming a path 34, a representative kinematic curve, obtained by interpolation of the trace, can be viewed on a screen.
• the touch-sensitive plate 18 is integrated in an object 16 of the interactive tablet type, itself connected to the electronic central unit 12 which is external to the object 16.
• the touch plate 18 may be transparent, made of glass and integrated into an on-board electronic device including the electronic central unit 12, such as a mobile phone or any other portable digital personal assistance device. In this case, it can also fulfill the display screen function of the kinematic curve obtained by interpolation of the detected pattern 34.
• the estimate of the frequency shift of the only fundamental eigenmode in each of the two principal directions (length and width) can enough to go back to the position (x, y) of the contact.
• the fundamental mode is indeed particularly interesting because that it is the one associated with the smallest number of vibration nodes in the touch plate 18, in particular only the areas of attachment of the tactile surface on its chassis according to the preferred directions D1 and D2. But when the touch surface becomes more complex, especially when it is no longer flat, such as a three-dimensional hull polygonal periphery, it may be advantageous to play on the following parameters to remove any ambiguity on the position of the contact:
• the excitation spectrum of a transmission transducer may advantageously be a frequency-modulated carrier pulse, the modulation being linear in time and between the reference fundamental resonant frequency and the double of this frequency in the direction considered.
• the transducers E1 and E2 are thus also connected to the receiver 24, and the transducers R1 and R2 to the transmitter 22. Each transducer E1, E2, R1 or R2 can thus be requested by the electronic central unit. 12 in transmission or reception.
• the tactile surface 18 is in the form of a three-dimensional shell of complex shape and having no particular axis of symmetry.
• This shell is fixed by four spacers arranged in attachment areas 36 to a frame 38 forming a rigid support. It comprises for example, as in the previous example, two pairs of emitter / receiver transducers E1, R1 and E2, R2 arranged in two main directions D1 and D2 characteristic of its shape.
• the emitting transducers E1 and E2 emit alternately, while the receivers R1, R2 receive simultaneously.
• the transmitter / receiver roles can be switched according to the contact position observed as a first approximation, as recommended in the previous example as well.
• the fundamental resonant frequency of the shell is excited by an electrical pulse with linearly modulated frequency carrier, the carrier scanning N resonant frequencies of the shell, in particular the fundamental frequency and the (N-1) first harmonic frequencies.
• N first resonance frequencies are in fact generally the most sensitive to the frequency shift generated by a point contact or a touch.
• the contact surface is always negligible in front of the active surface of the shell, that is to say generally less than 1% of the active surface of the shell so that the frequency shift is practically the same depending on whether the contact is established with the pulp or with the tip of a plastic stylet.
• the position of the contact is then determined by comparing an offset vector with N measured components with a base of reference vectors with N components each corresponding to a predetermined location.
• a device can provide to provide a validation signal to a user, whenever a contact is detected.
• the electronic central unit 12 can also be programmed, in response to the detection of a frequency shift of at least one eigen mode of vibration of the touch surface 18, due to the presence of a locally deforming contact , excite at least one of the emission transducers E1 or E2 with the aid of an electrical validation signal generating vibroacoustic waves.
• the vibroacoustic frequency of these vibrations generated by the validation signal can be related to the detected frequency offset: in particular, if a frequency shift of at least the two fundamental eigen modes in the two directions D1 and D2 is detected, this vibroacoustic frequency can be detected. be multiple and include at least the frequencies of the fundamental modes shifted.
• the transmitter 22 must be connected to the spectral analysis module 26 and / or to the analysis module 28.
• a predetermined frequency offset of the resonant frequencies of the shell is also possible, not by pressing on the shell at any point, but by creating a priori in the shell locally delimited areas and functionalized specific deformability, including monostability or bistability asymmetric.
• Such localized functionalized zones are illustrated in FIG. 2 and have the references 40 and 42. They are, for example, circular in shape and formed by stamping the shell 18 in certain predetermined locations or by plastic injection providing for a local reduction of the thickness of the hull on their periphery.
• Providing these locally delimited and functionalised zones with specific deformability in the shell 18 has the advantage of generating, when these zones are deformed by pressure according to a predetermined specific stroke / force law, much larger resonance frequency shifts of the hull 18. than the previously mentioned offsets more generally due to contacts at any points of the shell.
• these frequency offsets can vary between two extreme positions of a monostable or bistable zone, a rest position and a depressed position, so as to facilitate the recognition of the activation of the zone or to increase the immunity of this zone. to excitations by parasitic noises.
• bistable zones when such a zone is depressed, its resetting, that is to say its return to its initial position not depressed, can be obtained by combining two bistable zones that can not be depressed simultaneously, the depression of the one rearming the other and vice versa.
• FIG. 3A schematically shows in section a bistable zone, for example one of the zones 40 or 42 of FIG. 2.
• the ends situated at the periphery of this bistable zone are schematically represented as being fixed for the sake of simplification, but they are in fact fact connected to the rest of the deformable shell 18 which is also likely to deform, to a lesser extent, in the presence of a contact in the bistable area.
• zone 40 or 42 is asymmetrical bistable, noting d the normal displacement measured at the center of its surface and F the intensity of a normal force applied at its center (see Figure 3B), we obtain the law race / effort shown in Figure 3C.
• the position 0 ⁇ d ⁇ d top corresponds to the position "2" before changing elastic mode of deformation of the bistable zone.
• the position d d bo t associated with a negative force intensity threshold - F bot , causing a return tilt towards the first stable position "1”, also corresponds to an elastic deformation according to the position "3".
• the position d top ⁇ d ⁇ d end corresponds to the position "4" after changing elastic mode of deformation of the bistable zone.
• the asymmetry of the bistability of the zone 40 or 42 is related to the difference in intensity between F, op and F bot .
• the static stresses associated with the two stable positions "1" and "5" are different and associated with different dynamic elastic constants so that the resonant frequencies of the shell 18 associated with the two stable positions will also be different. . This will help to distinguish these two positions.
• zone 40 or 42 is not bistable but monostable.
• the race / force law also has a slope break, but there is no stable position at zero force other than the starting position.
• the zone 40 or 42 can then be depressed to a limit position of elasticity for which the slope increases very strongly.
• the lateral static stresses imposed on the shell 18 shift its resonant frequencies by a recognizable and characteristic quantity, on the one hand, of a contact on this zone and, on the other hand, of his depression.
• the frequency offset is then the accumulation of a blockage of the fundamental resonance of the shell 18 along the axis considered and a change of agreement related to changes in internal mechanical stresses at inside the hull that modify its elasticity properties, so in particular the speed of propagation of the bending waves and consequently the fundamental resonant and harmonic frequencies associated.
• the relative frequency offsets between the two extreme positions of the deformable zone can be previously recorded.
• a similar reasoning is also applicable for a deformable zone according to a more monotonous race / effort law, for example increasing monotonous.
• the shell 18 has several locally delimited and functionalised areas with specific deformability, these can be of different sizes, which generates specific frequency offsets for each between them. It will be noted that these bistable or monostable zones make it possible to create specific frequency shifts that are constant over time and return to creating in the hull 18 voltage or bistable or monostable static stress situations associated with bistable and monostable fundamental and harmonic resonance frequencies. .
• Figure 4 shows in section the shell 18 illustrated in Figure 2 in a plane including the axis D1, according to a first variant.
• a first spacer 44 rigidly secures the shell 18 on the frame 38 at the location where the transducer E1 is located.
• a second spacer 46 rigidly secures the shell 18 on the frame 38 at the location where the transducer R1 is located.
• the shell is deformable, in particular at the areas 40 and 42 which are, in this variant, formed by stamping so as to be monostable.
• the transducers E1 and R1 are piezoelectric pellets PZT type and shape favoring a radiation in the direction D1.
• the spacers are for example made in the same mold as the shell 18. They could also be riveted or come pinch the shell 18 with the help of clamping screws.
• Figure 5 shows in section the shell 18 shown in Figure 2 in a plane including the axis D1, according to a second variant.
• the zones 40 and 42 are formed in the shell 18 by plastic injection providing a local reduction of the thickness of the shell on their periphery so as to be bistable.
• the transducers E1 and R1 are respectively embedded in the struts 44 and 46 themselves made in the same mold as the shell 18.
• Figure 6 shows in section the shell 18 shown in Figure 2 in a plane including the axis D1, according to a third variant.
• the zones 40 and 42 are formed in the shell 18 by plastic injection as in the second variant.
• the transducers E1 and R1 are of annular shape, with alternating polarization and respectively mounted on annular turnings 48 and 50 of the struts 44 and 46.
• the annular turnings 48 and 50 of these struts 44 and 46 are for example obtained by injection plastic.
• the transducers E1 and R1 are ceramics of the PZT type having a silvering return of the internal electrode to facilitate an electrical contact without having to resort to a conductive adhesive.
• the spacers 44 and 46 are made in the same mold as the shell 18 and fixed to the frame 38 by clamping screws. They are solid between their annular machining and the shell 18. In this configuration, the thickness of the annular machining of a spacer is preferably equal to the diameter of the rod of the spacer. Alternatively, the spacers 44 and 46 could be hollow and the shell 18 fixed to the frame 38 by rivets through these spacers in their length. In this configuration, the thickness of the annular machining of a spacer is preferably equal to twice the thickness of the inner wall of the rod of the spacer.
• An advantage of this third variant lies in the fact that the alternating polarization annular transducer E1 and R1 generate or detect a bending mode transmitted to or received from the shell 18 via the spacers 44 and 46.
• the annular turns of the spacers on which are Glued annular transducers are an effective way to couple the vibratory bending energy of the hull 18 in bending wave in the transducers.
• the line of separation of the alternating polarization of each transducer imposes a directivity diagram of the bending wave generated in the shell 18.
• the polarization separation line alternate can be positioned to be parallel to the edge of the hull.
• the emission and / or reception intensity is then maximum in the median axis perpendicular to the separation line of the alternating polarizations.
• This configuration of the transducers also applied to the transducers E2 and R2, makes it possible to better generate and selectively detect bending modes within the shell 18 and makes the frequency shift location method more sensitive to point contacts.
• the directivity of the transducers also makes it possible to better decouple the axes D1 and D2 of the hull 18. The decoupling is also easier if the hull is not fixed rigidly around its entire periphery but only locally in the fastening zones 36.
• Another advantage of this third variant is to make the transmitting and receiving transducers totally invisible.
• Another advantage of providing fixing struts is to allow the shell, in pulse transmission mode, to effectively perform a loudspeaker function thanks to the presence of a resonance volume between the shell and its support.
• the hull In pulse reception mode, the hull can be used receiving antenna for the receiving transducers and performing a high sensitivity microphone function.
• a method of locating a locally deforming contact on a deformable tactile surface 18 such as the touch plate of FIG. 1 or the three-dimensional shell of FIG. 2 will now be detailed with reference to FIG.
• the electronic central unit 12 starts a step 100 of monitoring the outer face of the deformable tactile surface 18 followed by a step 200 of locating a contact.
• pulse elastic mechanical waves are emitted (102) in a characteristic main direction (D1 or D2) in the deformable tactile surface 18 from a transmission transducer (E1 or E2 for example). They propagate therein according to two distinct propagation phases: a first phase of transient propagation, extending from the instant t 0 to a time t i, during which the emitted wavefront reaches the corresponding receiving transducer (R 1 or R2 for example) in the direction considered; a second stationary propagation phase, extending from the instant ti to a monitoring end time X 2 , during which the emission of the pulsed elastic mechanical waves in the direction considered generates a resonant vibration of the deformable tactile surface 18 according to at least a clean mode.
• the emission transducer chosen for this monitoring step is, for example, excited by step-type electrical pulses, Dirac pulses, or preferably pulses of duration T with carrier modulated linearly in frequency over a spectrum [f 0 ; 2f 0 ] according to a law of type: where f 0 is the frequency of
• the duration T of the pulse can be chosen of the order of 10 ms.
• a linear pulse modulated linearly in frequency may be preferred.
• the electrical excitation pulses of the emission transducer can be modulated over an extended spectrum [f 0 ; 2Of 0 ].
• the monitoring step 100 comprises a detection 104 of this resonant vibration by the receiving transducer associated with this direction, for obtaining at least one signal picked up. This detection 104 is started at a time t 3 and continues until a time t 4 end of detection 106 by measuring the signal picked up during this time interval.
• the monitoring step 100 is followed by a step 200 of locating a contact during which the electronic central unit 12 identifies and locates a possible deforming contact on the touch surface 18. More specifically, during this step 200, the spectral analysis module 26 of the electronic central unit 12 detects at least one amplitude peak of the spectrum of the signal picked up in a predetermined frequency band: this amplitude peak is located at the frequency of one mode vibration of the tactile surface 18, in particular at least the fundamental eigen mode. When several amplitude peaks are detected, it is the fundamental eigen mode but also at least a harmonic eigen mode. Then it provides the result of this detection analysis module 28.
• the analysis module 28 compares the eigen modes detected to corresponding eigen modes without reference contact in the direction considered, deduces the respective offsets of these eigen modes detected , then estimates the position of a possible contact as a function of these offsets. In the case where the touch surface has specific zones monostable, it is also possible, as mentioned above, to measure the force of the contact. Finally, optionally, as mentioned above also, a validation signal can be issued in response to the detection and location of a contact.
• a device and a method for locating a locally deforming contact on a deformable tactile surface make it possible to locate and characterize contacts as different as a single or extended touch, short or long, caressing or unfriendly contact, etc., provided that they sufficiently block the surface in resonance and for a sufficiently long time, to generate eigenfrequencies.
• the tactile surface is deformable lengthens the duration of the contacts and facilitates their detection, including when it comes to impacts.
• the implemented principle of estimating frequency offsets is also sufficiently simple to be implemented in microcontrollers from the trade and to provide a short response time, usually between 1 and 100 ms. It can thus be implemented so as to be repeated for the detection of plots (ie a succession of contacts).
• Another advantage is to be able to obtain satisfactory results, for example millimetric localization accuracy, from a limited number of transmitters and receivers.
• at least a pair of transmitting and receiving transducers by main direction characteristic of the tactile surface may suffice.
• this embodiment has an increased immunity to ambient acoustic vibrations and noises or adhesives and stains in the absence of interaction, because the touch surface must be blocked or even mechanically tensioned in these locally deformable areas so that Frequency shifts characteristic of an interaction appear. It also has the advantage of providing a keypad without added mechanical key.
• the invention is not limited to flat glass surfaces, but also applies to curved surfaces and plastic or metal shells, which multiplies the possible applications.
• the closed three-dimensional cases forming a resonance chamber in particular adapted to the realization of piano-like touch-sensitive musical instruments with electromechanical excitation, the excitation comprising two steps, the first consisting in detecting the contact position of a finger on the shell and the second consisting in producing, immediately after the location of the contact, a pulsed sound return by exciting at least one transmitting transducer by a power signal at a frequency corresponding to the measured and desired frequency offset, possibly spectrally enriched depending on the acoustic rendering sought.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Theoretical Computer Science (AREA)
• Physics & Mathematics (AREA)
• Human Computer Interaction (AREA)
• General Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Force Measurement Appropriate To Specific Purposes (AREA)
• Position Input By Displaying (AREA)
• Length Measuring Devices Characterised By Use Of Acoustic Means (AREA)
• Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

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• 2009
  • 2009-07-29 FR FR0955322A patent/FR2948787B1/fr not_active Expired - Fee Related
• 2010
  • 2010-06-02 US US13/386,042 patent/US9007348B2/en not_active Expired - Fee Related
  • 2010-06-02 WO PCT/FR2010/051070 patent/WO2011015733A2/fr active Application Filing
  • 2010-06-02 JP JP2012522205A patent/JP5488942B2/ja not_active Expired - Fee Related
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