CONTROL DEVICE INTENDED TO CONTROL A FUNCTION OF A MOTOR VEHICLE

Abstract

A control device to control a motor vehicle function, includes a touch screen element having an external surface equipped with one or more control zones assigned to a specific function of the vehicle, the touch screen element supporting one or more elementary sensors positioned in line with one of the control zones. The elementary sensor(s) being capable of generating at least one signal in response to an action performed by the user on at least one of the control zones, - at least one actuator configured to provide a user with haptic feedback through a translational movement of the touch screen element, and in just-one direction of travel, - a control unit configured to receive the signal generated by the elementary sensor(s) and to control the actuator in response to the signal, wherein the control device has components to keep the touch screen element aligned in the vibration plane.

Description

TECHNICAL FIELD

The present disclosure relates to the field of control interfaces of the vehicle passenger compartment functions.

BACKGROUND

Driving a motor vehicle involves interactions between the driver and the vehicle and, as such, a motor vehicle is provided with various control members disseminated in the passenger compartment of the vehicle.

The control members traditionally comprise push or rotary buttons, sliders on which the driver or a passenger act to control vehicle functions such as the infotainment system, lighting, central locking, air conditioning, etc.

In recent years, we have witnessed the transformation of essentially electromechanical control members based on buttons, switches, micro-switches, potentiometers, etc. into digital control interfaces in which the driver or passenger control is converted into an electrical signal that a computer processes to act on an actuator which transcribes the instruction given by the driver or passenger.

Multifunction control interfaces are used to control electrical or electronic systems, such as an air conditioning system, an audio system or even a navigation system. The control interfaces can generally be associated with a generally capacitive touch screen and allow navigation in drop-down menus.

However, in the presence of more and more numerous functions, it is necessary to improve the ergonomics of the man-machine interfaces. When a user presses on the touch surface, the location of the position can be determined by sensing the contact or the pressure where the force is exerted. In this case, a pressure of the user is for example associated with the selection of a command. Furthermore, to signal to the user that his command has been taken into account, whether in a normal driving or stopping situation but also in a degraded situation (blind handling, heavy cognitive load), it is important that the user has haptic feedback so as to remain focused on the road by reducing the cognitive force associated with verifying the performance of his action on the touch surface.

For this, so-called haptic feedback control modules are already known including actuators, such as electromagnetic actuators, connected to the interface module to transmit a movement of vibrations, so that the user perceives a haptic feedback informing him that his command has been taken into account.

To make it possible to give the user a haptic feedback in line with his action, it is preferable to detect both the action on the command and the force of the action on the command. On a traditional command, the action is activated by a mechanical movement. On a touch command, it is appropriate to avoid «false detections» to differentiate the intention from the action. The intention can, for example, result in the positioning of a finger of the user near or in contact with the command that he wants to activate. This intention is generally detected by means of capacitive sensors. The action on the contrary consists in an accentuated pressure on the command so as to trigger the command. This action can, for example, be detected by pressure-sensitive sensors.

This notion of intention and action, in addition to avoiding false detections, is very important to give the user appropriate haptic feedback and above all at the right time.

Indeed, if the haptic feedback is sent before the user has produced the action, his finger risks not being in sufficient contact with the control surface for him to perceive the haptic effect.

In the same way, if the haptic feedback is sent after the action has been produced, the user risks interpreting a lack of support for his action, or even analyzing this as a malfunction of his command interface.

To avoid these problems, it is therefore fundamental to propose control devices that make it possible to clearly distinguish between intention and action.

In the control devices currently on the market, this distinction between intention and action turns out to be imperfectly realized.

Thus, the control devices equipped with capacitive sensors only do not make it possible to differentiate the intention from the action, because the capacitive sensor triggers the action as soon as it detects the finger on the command. Moreover, these capacitive sensors do not make it possible to detect the pressing force, and, consequently, do not make it possible to vary the haptic feedback accordingly.

SUMMARY

To overcome this defect, it is currently proposed to combine in the same control device of the capacitive sensors, making it possible to detect the intention, and sensors sensitive to pressure, making it possible to detect the action.

Among the pressure-sensitive sensors, there are in particular micro-switches and strain gauges.

In the control device shown in FIG. 1, the control device 1 comprises a slab 2 mounted in sliding manner on a frame 3 so that it can be displaced in translation in a direction Dx, under the impulse of an actuator (not shown), and in a direction Dz, under the action of pressure exerted by a user. When a user approaches one of his fingers to an upper zone of the slab 2 which is positioned directly above a capacitive sensor 4 fixed under the slab 2, he actuates the capacitive sensor 4 which generates a signal to alert a control unit (not shown) of the user intention to activate a command specifically assigned to said zone. Subsequently, when the user approaches his finger closer until he comes into contact with said upper zone, he causes a displacement of the slab 2 in the direction Dz at the level of the upper zone, which depresses a micro-switch 5 arranged under the slab 2. This micro-switch 5 generates a signal in response which is sent to the control unit, which can then trigger the command and the corresponding haptic feedback. The drawback of this type of control device is the sometimes-oblique orientation of the slab 2 at the time of application of the haptic feedback, as shown in FIG. 1, which does not allow constant guidance of the slab 2 during its translation in the direction Dx, and, therefore, can lead to poor perception of the haptic feedback by the user. Also in some cases, it may happen that the inclined position of the slab 2 leads to a lack of contact between the slab and the micro-switch, in particular when the user presses on an area of the slab 2 which is far from the micro-switch. This therefore results in a non-detection of the action and, consequently, an absence of haptic feedback. Moreover, the micro-switch does not make it possible to measure the strength of the force which is applied by the user and therefore to modulate the haptic feedback as a function of the applied force.

The control device represented in FIG. 2 differs from that of FIG. 1 by the use of strain gauges 6 instead of micro-switches. Even if this configuration partially solves the problems mentioned above, it should be noted that the slab 2 is still positioned slightly obliquely when the haptic feedback is applied, which hinders the guiding of the slab 2 during its translation in the direction Dx: the haptic effect may therefore not be correctly perceived by the user.

The two aforementioned systems also imply that the slab, in addition to allowing the vibration movement of the haptic feedback (direction substantially perpendicular to the action of the user finger), is also free to move in the direction substantially parallel to the pressing of the user finger. This need to have at least two degrees of freedom runs counter to compliance with clearances and outcrops and therefore to a better quality of appearance of the parts thus equipped with a haptic feedback device.

The present disclosure provides a control device that does not have the aforementioned drawbacks.

To this end, the disclosure concerns a control device intended to control a function of a motor vehicle, the control device comprising:

• a touch screen comprising an outer surface provided with one or more control zones each assigned to a specific function of the motor vehicle, the touch screen supporting one or more elementary sensors each positioned directly above one of said control zones, said elementary sensor(s) being capable of generating at least one signal in response to an action exerted by the user on at least one of said control zones,
• at least one actuator configured to provide a user with a haptic feedback by translational displacement of the touch screen in a plane, called the vibration plane, and in a single displacement direction,
• a control unit configured to receive said at least one signal generated by said elementary sensors and to control said at least one actuator in response to said signal,

in which the control device comprises support and guide means intended to keep the touch screen aligned in the plane of vibration and in which each of the elementary sensors comprises at least one insulating substrate on which are deposited conductive tracks forming a capacitive sensor and an assembly of conductive or semiconductive nanoparticles in colloidal suspension in an electrically insulating ligand, said assembly forming a force sensor.

Thus configured, the control device of the disclosure will make it possible to generate a haptic effect which is correctly perceptible by the user while ensuring a better quality of appearance of the parts equipped with the control device.

According to other characteristics, the control device of the disclosure may comprise one or more of the following optional characteristics considered alone or in combination;

• at least one of the control zones forms a portion of the outer surface of the touch screen on which a finger of a user can press, said at least one control zone being arranged contiguous to one of the elementary sensors such that pressing said at least one control zone generates a deformation of said elementary sensor which can be detected by the force sensor of said elementary sensor.
• said at least one actuator comprises a fixed part connected to a frame of the device and a movable part in an air gap of the fixed part, the movable part being connected to the touch screen.
• the movable part of said at least one actuator comprises a magnet or an array of magnets and the fixed part of said at least one actuator comprises a coil or an array of coils.
• said at least one actuator comprises a rotary motor provided with a rotary shaft, the rotary shaft constituting the movable part of said at least one actuator.
• said at least one actuator comprises an inertial actuator by translation.
• the support and guide means comprise several fixing clips, each of the fixing clips being secured to a frame of the device, and several fixing lugs, each of the fixing lugs being secured to the touch screen, the fixing lugs being configured to cooperate with the fixing clips to allow clipping between the touch screen and the frame and to prevent the displacement of the touch screen relative to the frame in a direction perpendicular to the plane of vibration while allowing guidance of said touch screen during its displacement in translation vis-à-vis the frame in the direction of displacement.
• the fixing lug has a protrusion at its free end and each fixing clip is provided with two tabs that are elastically deformable in the plane of vibration and in a direction perpendicular to the direction of displacement, said tabs being configured to form a passage opening through which the fixing lug can be inserted, said passage opening not allowing, in an undeformed state of the fixing clip, the passage of the protrusion of the fixing lug.
• the control unit is configured to vary the haptic feedback generated by said at least one actuator as a function of the intensity of pressure exerted by the user on at least one of said control zones.

The disclosure also relates to a motor vehicle comprising a control device as defined above.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is described below according to several preferred embodiments, in no way limiting, and with reference to FIGS. 1 to 17 in which:

FIG. 1 is a schematic view of a first example of a control device according to the prior art;

FIG. 2 is a schematic view of a second example of a control device according to the prior art;

FIG. 3 is a schematic view of a control device according to the disclosure;

FIG. 4 is a perspective view of a passenger compartment element of a motor vehicle incorporating a control device according to the disclosure;

FIG. 5 is an enlarged view of the passenger compartment element shown in FIG. 4, the control device being shown in its normal position of use;

FIG. 6 is a view similar to FIG. 5, the control device being shown in a disassembled state;

FIG. 7 is an enlarged view of an upper part of the control device shown in FIG. 6;

FIG. 8 is an enlarged view of a support and guide element of the control device shown in FIG. 7;

FIG. 9 is an exploded perspective view of an actuator that can equip the control device according to the disclosure;

FIG. 10 is a top view, according to a first embodiment, of an elementary sensor usable in the control device of the disclosure;

FIG. 11 is a sectional view along section line AA of the sensor of FIG. 10;

FIG. 12 is a view similar to FIG. 11 but according to a second embodiment of an elementary sensor usable in the context of the disclosure;

FIG. 13A is a sectional view of an elementary sensor according to another embodiment during a proximity detection;

FIG. 13B is a view similar to FIG. 13A during a detection of a touch;

FIG. 13C represents the time evolution of the signal coming from the force sensor formed by the elementary sensor of FIGS. 13A and 13B;

FIG. 13D represents the evolution over time of the signal coming from the capacitive sensor formed by the elementary sensor of FIGS. 13A and 13B;

FIG. 14 represents, in an exploded top view, an embodiment of a touch surface combining a plurality of elementary sensors that can be used in the context of the disclosure;

FIG. 15 shows the flowchart of an example of a method implementing an elementary sensor that can be used in the context of the disclosure;

FIG. 16 is an example of a flowchart of a method implementing a touch surface integrating an elementary sensor that can be used in the context of the disclosure; and

FIG. 17 shows the variation of the voltage delivered as a function of time by a force sensor implementing an assembly of nanoparticles whose conductivity varies according to the force applied to said sensor.

The drawings are representations in principle and are not representative of the scale of the various elements they represent.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to FIG. 3, there is shown a control device 10 in accordance with the disclosure. This control device 1 comprises a slab 12 slidably mounted on a frame 14 so that it can be displaced in translation in a direction Dx (substantially perpendicular to the action of the user finger) under the impulse of an actuator (not represented), thus generating a haptic effect which can be perceived by a user who touches the upper surface of the slab 12 with one of his fingers. The direction Dx is parallel to a plane P, called the vibration plane. The slab 12 rests on support elements 16 in such a way that it cannot be displaced relative to the frame 14 in a direction Dz perpendicular to the vibration plane P. These support elements 16 are moreover configured to guide the slab 12 during its displacement along the direction Dx. The operation of the control device 10 is based on the use of very specific elementary sensors 20 arranged under the lower surface of the slab 12 directly above control zones 18 formed at the level of the upper surface of the slab 12. These elementary sensors 20 will be able to generate at least one signal in response to an action exerted by the user on at least one of said control zones, in particular a more or less strong pressure exerted by a user by means of one of his fingers on one of the control zones 18. Preferred examples of such elementary sensors are described in particular in the following paragraphs in connection with FIGS. 10 to 17. These preferential elementary sensors combine on the same substrate capacitive sensors and force sensors. These elementary sensors will thus be able to detect the intention of a user by means of their capacitive sensors and the action of this user by means of their force sensors. The force sensors will notably make it possible to measure the pressure exerted by a user with his finger. Thus, when a user approaches one of his fingers to a control zone 18 of the slab 12 which is positioned directly above one of the elementary sensors 20, he actuates the capacitive sensor of this elementary sensor 20, which generates in response a signal to alert a control unit (not shown) of the user intention to activate a command specifically assigned to said control zone 18. Subsequently, when the user approaches his finger closer to come into contact with said control zone 18, he presses on the force sensor of this elementary sensor 20. This pressure is measured and a signal is generated in response and sent to the control unit, which can then trigger the control and the corresponding haptic feedback. The advantage of these elementary sensors 20 is that they are sensitive to pressure and do not require movement of the slab 12 in the direction Dz. Thus, when applying the haptic effect, the slab 12 remains constantly aligned in the vibration plane P, as shown in FIG. 3. This position in the same plane allows having improved guidance of the slab 12 during its translation in the direction Dx, and, therefore, provides a better perception of the haptic feedback by the user. Other sensors may nonetheless be used instead of the preferred elementary sensors described above. In particular, a combination of capacitive sensors and pressure sensors using FSR («Force Sensing Resistor») technology, that is to say using pressure-sensitive resistors, could constitute a possible alternative solution.

Referring to FIGS. 4 to 6, there is shown a particular embodiment of a control device according to the disclosure.

In this embodiment, the control device 10 is integrated into a passenger compartment element 100 of a motor vehicle, this passenger compartment element 100 being able for example to be a central console separating the two front seats of the motor vehicle. This control device 10 consists in particular of a slab 12 that is substantially flat and of rectangular shape. The slab 12 is fixed on a frame 14 by means of several fixing clips 161 secured to the frame 14. As shown in FIG. 5, these fixing clips 161 are configured to hold the slab 12 fixed relative to the frame 14 in one direction Dz perpendicular to a plane P defined by the slab, while allowing a translation of said slab 12 in a direction Dx parallel to the plane P. This translation can take place under the action of an actuator 30 disposed between the frame 14 and the slab 12.

The upper surface of the slab 12 is provided with a control button 18 of circular shape. When the user presses said control button 18, he actuates a sensor (not visible in FIGS. 4 to 6) arranged directly above the control button 18. This actuation causes a signal to be sent to a unit (not represented) which, depending on the received signal, controls the actuator 30 so as to cause a greater or lesser relative displacement of a movable part of this actuator 30, which is fixedly connected to the slab 12, relative to a fixed part of the actuator 30, which is fixedly connected to the frame 14. This results in a relative displacement of the slab 12 with respect to the frame 14 under the action of the actuator 30, which generates a haptic effect in the slab 12.

An example of an actuator 30 that can be used in the context of the disclosure is shown in particular in FIG. 9. This actuator 30 comprises in particular a hollow container 31 of parallelepiped shape, said container 31 delimiting a housing 36 intended to contain an array of coils 34 and an array of magnets 35, and a cover 32 configured to close an upper opening of said container 31. The array of coils is fixed to an internal face of the container 31 and the array of magnets is fixed to an internal face of the cover 32 facing the housing 36. The cover 32 and the container 31 are fixed to each other so as to allow a movement in relative translation of the cover 32 vis-à-vis the container 31 in a displacement direction Dx. Thus, during the operation of the actuator 30, the array of coils 34 is supplied with electric current and generates a magnetic field which results in a translational movement of the array of magnets 35. The array of magnets 35 being fixed to the cover 32, the latter also is displaced in the direction Dx with respect to the container 31. By respectively fixing the cover 32 on the slab 12 and the container 31 on the frame 14, it is thus possible to generate a relative movement in the direction Dx of the slab 12 vis-à-vis the frame 14 by means of the actuator 30. This relative displacement makes it possible to generate haptic vibrations in the slab 12.

Another possible variant of the actuator 30 could consist of a rotary motor equipped with a rotary shaft, the rotary shaft constituting the movable part of the actuator and the rotary motor being secured to the fixed part of the actuator. This type of actuator is an inertial actuator, the rotating part is not connected to the slab but generates the vibration by a rotating weight.

Another possible variant of the 3D actuator could consist of an inertial weight vibrating by translation in a coil.

Referring to FIGS. 7 and 8, there is shown in detail the additional elements allowing the sliding fixing of the slab 12 on the frame 14. The first element consists of the fixing clips 161 mentioned above and the second element consists of fixing lugs 162 extending perpendicularly from the lower surface of the slab 12. These fixing lugs 162 may be secured to the slab 12 or fixed to the latter by any conceivable fixing means. The fixing lugs 162 are configured to fit inside the fixing clips 161 so as to ensure a sliding fixing of the slab 12 on the frame 14, the slab 12 being able to slide only along the direction Dx once fixed on the frame 14. For this purpose, each of the fixing lugs 162 consists of a straight section 163 provided with a protrusion 164 at its free end and each fixing clip 161 is provided with two tabs 165 elastically deformable in the plane of vibration P and in a direction Dy perpendicular to the direction Dx. In the unassembled state shown in FIG. 8, the tabs 165, 166 form a passage opening whose width in the direction Dy is sufficient to allow the insertion of the straight section 163 of the fixing lug 162, but insufficient to allow passage of the protrusion 164. During the assembly operation, the slab 12 is first arranged so as to align the straight section 163 of each fixing lug 162 with a passage opening of one of the fixing clips 161 and the slab is then moved in the direction of the frame 14 parallel to the direction Dz until the protrusion 164 abuts against the tabs 165, 166. By pressing sufficiently on the slab 12, it is possible to deform the fixing clip 161 so as to widen the passage opening, thus allowing the passage of the protrusion 164 through the passage opening. The protrusion 164 is then positioned under the tabs 165, which return to their undeformed state shown in FIG. 8. A reverse displacement of the fixing lug 161 in the direction Dz is then prevented, in particular by the presence of flanges 166 at the end of the tabs 165, which, being oriented perpendicular to the direction Dz, constitute abutment zones for the protrusion 164. The combination of the fixing clips 161 and the fixing lugs 162 therefore allows fixing by clipping of the slab 12 on the frame 14. These complementary fixing means prevent, as described above, the movement of the slab 12 relative to the frame 14 in the direction Dz. Furthermore, due to the possibility for the cross section 163 of each fixing lug 162 to slide along the direction Dx through the passage opening defined by the tabs 165, while being held in position by the support elastic exerted by the tabss 165, these complementary fixing means make it possible to guide the slab 12 during its movement vis-à-vis the frame 14 in the direction Dx under the action of the actuator 30.

FIG. 10 represents an embodiment of an elementary sensor 20 that can be used in the control unit of the disclosure. This elementary sensor 20 comprises an insulating substrate 210 on which are deposited, by techniques known from the prior art, concentric conductive tracks 221, 222 constituting a capacitive sensor.

The insulating substrate 210 is, according to exemplary embodiments, a polymer, for example a polyimide or a PET, or a ceramic.

Said concentric tracks 221, 222 are for example made of copper, ITO (In₂O₃ -SnO₂) to produce a transparent sensor or any other conductive material. They are deposited, for example, by photolithography or by soft lithography.

In the center of the sensor is deposited an assembly of nanoparticles constituting a force sensor.

According to an exemplary embodiment, suitable for producing a transparent sensor, said nanoparticles are ITO nanoparticles in colloidal suspension in an insulating ligand, for example an (aminomethyl) phosphonic acid (CH₆NO₃P).

According to other embodiments, the nanoparticles are zinc oxide (ZnO) nanoparticles or gold (Au) nanoparticles.

The assembly of nanoparticles 230 is a monolayer or multilayer assembly, deposited on the substrate, for example, by convective capillary deposition or by a so-called «drop evaporation» method as described in document EP 2 877 911, without these examples are neither exhaustive nor limiting.

The assembly of nanoparticles 230 is firmly linked to the substrate 210, for example via a chemical coupler.

For example, the chemical coupler is a silane (SiH4), capable of interacting with OH groups on the surface of the substrate previously activated by UV-Ozone treatment and comprising at the other end of the coupler a carboxylic group (COOH) capable of grafting onto an amine group (NH2) previously grafted to the surface of the nanoparticles.

The assembly of nanoparticles 230 constitutes a strain gauge, the electrical conductivity of which varies according to the relative distance between the nanoparticles of the assembly.

This variation of conductivity or vice versa of electrical resistance is attributed to the conduction by tunnel effect between the nanoparticles, and this effect provides a very high gauge factor, much higher than what is possible to obtain with a piezoresistive film, which makes it possible to measure very small deformations.

For example, the proportional variation of the resistance of such an elementary force sensor, consisting of an assembly of ITO nanoparticles in a ligand based on phosphonic acid, shows an exponential evolution of the response in function of the deformation undergone by said elementary sensor, with a gauge factor reaching the value of 85 over a deformation range of -1%, in compression, to +1% in tension for a resistance in the range of 2000.10³ Ohm in the absence of deformation.

Thus, this elementary force sensor is very sensitive and makes it possible to detect a pressing or touching force, even relatively weak, applied to said sensor, which can thus constitute its own test body. In other words, the deformation of the substrate is not necessary to detect an applied force and the arrangement represented in FIG. 10 is realizable on a rigid substrate such as silicon dioxide (SiO₂) or silicon nitride (Si₃N₄) while allowing a measurement of the force applied to the sensor.

With reference to FIG. 17, there is shown an example of variation of the voltage 102 delivered as a function of time 101 by such an elementary force sensor when a force is applied to said sensor, for example a touch. According to this example, the touch is applied between times t₀ and t₁. The intensity of the force is proportional to the difference V₁-V₀, in which the V₁ value is measurable and the V₀ value depends on environmental factors and is likely to vary over time, in particular with temperature.

Conductive tracks 240, represented here according to a principle representation, also deposited on the substrate 210, allow the electrical supply and the collection of data from the capacitive sensor and from the force sensor.

According to a first embodiment represented in FIG. 11, a protective layer 310 consisting of an insulating material, for example a polyimide, or a PET for producing a transparent sensor, is deposited on the sensor thus created.

According to this first embodiment, the combined elementary sensor has a diameter comprised between 10 mm and 30 mm and a thickness comprised between 50 µm and 300 µm without these values being limiting.

According to a second embodiment represented in FIG. 12, the combined elementary sensor is produced in 2 layers 401, 402, the first layer 401 comprising, according to this second embodiment, a substrate 2011 on which is deposited the force sensor 230 according to a technology identical to what has been explained above, and a protective layer 3101, and superimposed on this first layer 401, a second layer 402 comprising a substrate 2102 on which are deposited the conductive tracks 221, 222 producing the sensor capacitive.

A protective layer 3102 is placed on said capacitive sensor.

According to an example of implementation represented in FIGS. 13A and 13B, the elementary sensor is attached to one face of an insulating substrate 510, the opposite face 511 of said substrate being exposed to the touch.

Thus, the surface 511 of this substrate 510 is functionalized and makes it possible to detect a touch on this surface and to measure the force of application of this touch.

According to non-limiting embodiment examples, said substrate 510 may consist of a polymer, glass, ceramic, leather or wood. The sensitivity of the force sensor makes it possible to detect a slight deformation, and thus to detect and measure a touch force even if this substrate is relatively rigid.

As illustrated in FIG. 13A, when an electrically conductive object, for example a finger 500, is approached to the surface 511 thus functionalized, at a time t₀, its presence is detected, even before there is contact, as soon as the latter is at a distance less than or equal to a minimum distance 590 from the capacitive sensor.

This minimum distance 590 is adjustable according to the characteristics of the sensor and a threshold defined on the signal delivered by said capacitive sensor.

By way of example, the minimum distance is selected for any value between 0 and 10 mm depending on the intended application.

To this end, the sensor is connected to an electronic circuit able to perform these functions as well as the steps of the method described below.

Thus, at time t₀, as shown in FIG. 13D, by observing the value of signal 522 delivered by the capacitive sensor as a function of time 501, information 523 delivered by said sensor crosses a threshold C₀ corresponding to the crossing of the minimum distance 590. Then, as soon as the object 500 comes into contact with the surface, the information delivered by the capacitive sensor changes no more or very little, even if the applied pressure increases.

Returning to FIG. 17, when the proximity of the object 500 is detected, the value V₀ delivered by the force sensor at time t₀ is measured and taken as the reference value, by making this value correspond to a force equal to 0, since there is no contact, as shown in FIG. 13C, which represents the value 502 of the signal 503 delivered by the force sensor as a function of time 501, modified by the processing.

Thus, any drift phenomenon of the information delivered by the force sensor, in particular due to temperature variations, is compensated.

As shown in FIG. 13B, when the object 500 comes into contact with the functionalized surface 511 and applies a touch force thereon, the conductivity of the force sensor is modified in proportion to the applied force, and this delivers, as illustrated in FIG. 13C, information V₁ corresponding to a force proportional to V₁-V₀, corrected for the initial drift value V₀ of the force sensor 230.

When the touch pressure is released at time t₁, at a short instant (t₁+e) following this release, the object 500 is at a distance from the surface 511, greater than or equal to the minimum distance 590, and, as illustrated in FIG. 13D, the information delivered by the capacitive sensor crosses the threshold C₀ in the opposite direction.

When the crossing of this threshold C₀ is detected on the capacitive sensor, the information delivered by the force sensor is considered equal to 0. Thus, the delayed return to 0 of the information delivered by the force sensor, due to the hysteresis phenomena, is also masked.

Thus, the combined use of the force sensor and the capacitive sensor makes it possible to measure an applied force, and if necessary to trigger actions according to the level of this force, by overcoming the inherent drift and hysteresis phenomena to this type of force sensor and as shown in FIG. 17.

FIGS. 13A and 13B represent a combined sensor according to the first embodiment represented in FIG. 11, those skilled in the art understand that the same principles are applicable in the case of a combined sensor corresponding to the second embodiment represented in FIG. 12.

With reference to FIG. 14, a plurality of elementary sensors are associated in a grid so as to form a touch surface capable of detecting a touch, its location on the grid and the exerted pressure force.

FIG. 14 represents an embodiment combining a plurality of sensors according to the embodiment represented in FIG. 12. Those skilled in the art will be able to adapt this principle to the embodiment of the elementary sensor represented in FIG. 11.

Said touch surface comprises a substrate 610, made of an electrically insulating material, and comprising a surface exposed to touch.

On the face opposite to this surface exposed to touch of the substrate 610 is added a first layer 620 comprising a grid of capacitive sensors 625, such as the upper layer 402 of FIG. 12.

Beneath the layer 620 carrying the grid of capacitive sensors is added a layer 630 comprising a grid of force sensors 635 made up of assemblies of nanoparticles, such as the lower layer 401 of FIG. 12.

According to a first embodiment (not shown), the number of force sensors 635 is equal to the number of capacitive sensors 625 and said force sensors are located centered with respect to the capacitive sensors.

Advantageously, the number of force sensors 635 is reduced relative to the number of capacitive sensors 625 and said force sensors are located centered, or not, relative to said capacitive sensors.

This embodiment, using a reduced number of force sensors is more economical.

Indeed, whatever the point of application of the force of touch on the touch surface thus created, the force of touch is evaluated, knowing this point of application, and deduced from the signals delivered by one of the force sensors, for example that closest to the point of application, or by combining the information delivered by several of these sensors, at least 3 force sensors for a flat touch surface, according to implementation variants.

The location of the point of application of the touch on the touch surface is obtained from the grid of capacitive sensors 625.

This principle remains valid in the case of multiple touch points.

This embodiment makes it possible to produce a touch surface comprising a high density of capacitive sensors, more economical to produce than the force sensors, and thus to obtain precise localization of the point(s) of application of the touch, then to evaluate the force applied during these touches by appropriate processing of the information delivered by a reduced number of force sensors 635 of more expensive construction, depending on the location of the point(s) of application of the touch.

The method implemented remains similar, namely that as soon as the proximity of a conductive object is detected at a distance less than or equal to the minimum distance 590 from one of the capacitive sensors, the value V₀ delivered by each of the force sensors is measured so as to readjust the information delivered by each of said sensors, the application force is determined by combining the information from said force sensors as a function of the location of the point of application of the force given by the capacitive sensors array, then, when the object moves away from the touch surface by a distance greater than or equal to the minimum distance, the force is reset to 0.

One skilled in the art understands that the use of a reduced number of force sensors compared to the number of capacitive sensors is applicable to a touch surface of a shape other than flat, for example a single or double curvature surface, as soon as that this form is stable.

For a flexible touch surface of variable shape, for example a touch surface applied to clothing, the embodiment comprising a number of force sensors equivalent to that of the capacitive sensors and centered with respect to the latter is preferable.

Thus, the device as described previously offers in its variants very varied application possibilities.

As illustrated in FIG. 15, the implementation of a method for detecting and measuring the intensity of a touch force by an electrically conductive object 500 on a touch surface comprising an elementary sensor as described below, whatever its embodiment, comprises, according to a frequency or by defined time intervals, the reading 710 of the signal coming from the capacitive sensor and the comparison 715 of the value of the signal thus read with a defined value C₀ representative of a minimum distance between an object and the capacitive sensor.

According to this embodiment, and with reference to FIGS. 13A and 13D, when this distance is less than or equal to a minimum distance, the signal delivered by the capacitive sensor is greater than or equal to a value C₀.

In the case 716 where the signal delivered by the capacitive sensor remains lower than C₀, no other action is triggered and the scanning of the signal at the frequency or by given time interval continues.

In the case 717 where the signal delivered by the capacitive sensor crosses the threshold C₀ and therefore an object is close to said sensor, during initialization steps of the force sensor, the value delivered by the force sensor is read 720 and during a drift determination step 730 the value V₀ thus read is used as a reference value.

The measurement of the force applied is carried out with respect to this reference as long as the object is in contact with the touch surface. To this end, the output signal from the capacitive sensor is compared 735 with the value C₀ corresponding to the minimum distance, and as long as 737 the value delivered by this sensor remains greater than the value C₀, the signal from the force sensor is measured 740 and, during a recalibration step 750, recalibrated with respect to the value V₀ determined during the drift determination step 730 carried out in the same acquisition sequence.

The method described in FIG. 15 in the case of an elementary sensor, extends to the case of a touch surface comprising as many elementary sensors, with additional steps consisting in locating on the grid of capacitive sensors the one where the proximity, and as a function of this information, apply the steps of reading the information delivered 720 of drift measurement 730, of measurement of the force applied 740 and of recalibration 750 to the force sensor closest to the capacitive sensor for which the proximity to touch is detected.

As illustrated in FIG. 16, in the case where the touch surface comprises a significantly greater density of capacitive sensors compared to the number of force sensors, during a step 810 of scanning, the information delivered by the capacitive sensors is probed at regular time intervals and the information delivered by each sensor is compared 815 with that, C₀, corresponding to the minimum distance threshold.

When this threshold is exceeded 817 on one of the sensors, during a location step 820, the position of the activated capacitive sensor is determined.

During a drift determination step 830 the information delivered by each of the force sensors is read and this information is assigned 840 to each of the respective force sensors as an adjustment value.

Throughout the touch 847, the information coming from the force sensors is acquired 850, readjusted 860 for each sensor by the value evaluated during the drift determination step 830.

Then, depending on the point of application of the force, determined during the location step 820, the force applied to the considered point is estimated 870 by combining the information from the force sensors.

Claims

1. A control device intended to control a function of a motor vehicle, the control device comprising:

a touch screen comprising an outer surface provided with one or more control zones, each of the one or more control zones being assigned to a specific function of the motor vehicle, the touch screen supporting one or more elementary sensors each of the one or more elementary sensors being positioned directly below one of said control zones, said elementary sensor(s) being capable of generating at least one signal in response to an action exerted by a user on at least one of said control zones,

at least one actuator configured to provide the user with a haptic feedback by translational displacement of the touch screen in a plane, called a vibration plane, and in a single displacement direction,

a control unit configured to receive said at least one signal generated by said elementary sensor(s) and to control said at least one actuator in response to said signal, the control device includes support and guide means intended to keep the touch screen aligned in the vibration plane and in that each of the elementary sensors comprises at least one insulating substrate on which are deposited conductive tracks forming at least one capacitive sensor and an assembly of conductive or semi-conductive nanoparticles in colloidal suspension in an electrically insulating ligand, said assembly forming at least one force sensor.

2. The control device according to claim 1, wherein at least one of the control zones forms a portion of the outer surface of the touch screen on which a user finger can press down, said at least one control zone being arranged contiguous to one of the elementary sensors such that pressing on said at least one control zone generates a deformation of said elementary sensor which is configured to be detected by the force sensor of said elementary sensor.

3. The control device according to claim 1, wherein said at least one actuator comprises a fixed part connected to a frame of the device and a movable part in an air gap of the fixed part, the movable part being connected to the touch screen.

4. The control device according to claim 3, wherein the movable part of said at least one actuator comprises a magnet or an array of magnets and the fixed part of said at least one actuator comprises a coil or an array of coils.

5. The control device according to claim 3, that wherein said at least one actuator comprises a rotary motor provided with a rotary shaft, the rotary shaft constituting the movable part of said at least one actuator.

6. The control device according to claim 3, that wherein said at least one actuator comprises an inertial actuator by translation.

7. The control device according to claims 1, wherein the support and guide means comprise several fixing clips, each of the fixing clips being secured to a frame of the device, and several fixing lugs, each of the fixing lugs being secured to the touch screen, the fixing lugs being configured to cooperate with the fixing clips to allow clipping of the touch screen on the frame and to prevent the displacement of the touch screen relative to the frame in a direction perpendicular to the vibration plane while ensuring guidance of said touch screen during displacement in translation vis-à-vis the frame in the displacement direction.

8. The control device according to claim 7, wherein the fixing lug has a protrusion at its free end and in that each fixing clip is provided with two tabs elastically deformable in the vibration plane and in a direction perpendicular to the displacement direction, said tabs being configured to form a passage opening through which is configured to be inserted the fixing lug, said passage opening not allowing, in an undeformed state of the fixing clip, the passage of the protrusion of the fixing lug.

9. The control device according to claim 1, that wherein the control unit is configured to vary the haptic feedback generated by said at least one actuator as a function of the intensity of a pressure exerted by the user on at least one of said control zones.

10. A motor vehicle comprising a control device according to claim 1.