CN117891363A - Touch-sensitive and pressure-sensitive multilayer film - Google Patents

Abstract

The present disclosure provides a touch-sensitive and pressure-sensitive multilayer film (17) comprising: a front face (21) having a control surface (25) with a plurality of control buttons (19); a back surface opposite to the front surface (21); and a first electrode group covering a first region of the front face (21), the first electrode group being arranged in a single layer. A single one of the electrodes of the first electrode set constitutes one of the electrodes of a first piezoelectric pressure sensor (31.1) adapted to detect a pressure exerted on the first area covered by the first electrode set, while the other electrodes of the first electrode set are electrodes each forming a capacitive touch sensor (33), each capacitive touch sensor (33) corresponding to a control button (19).

Description

Touch-sensitive and pressure-sensitive multilayer film

Prior Art

From document US 2021/0124258 A1 (hereinafter "document US' 458") a touch-and pressure-sensitive multilayer film is known, which comprises a front face provided with a control surface having a plurality of control buttons, a rear face opposite to the front face, and a first electrode set covering a first area of the front face, the first electrode set being arranged in the same layer.

More specifically, such a multilayer film is identified by reference numeral 8 in fig. 10 of document US' 458. This is a set of control buttons 16 mounted on the dashboard 49 of the vehicle. Referring to fig. 1 to 3 of US'458, each control button 16 has an upper electrode 10 and a lower electrode 11. The control buttons 16 share the piezoelectric material layer 5 interposed between the upper electrode 10 and the lower electrode 11. Each control button 16 is a dual sensor that incorporates both a capacitive touch sensor and a piezoelectric pressure sensor within itself.

According to document US 458, such a dual sensor has advantages compared to a simple capacitive sensor (see paragraphs 41, 42 and 67). By virtue of the ability of the control button 16 to detect not only a touch but also a pressure, accidental touches to the control button 16 can be distinguished from intentional actuation of the control button 16 by a user.

However, this embodiment of the control button 16 as a dual sensor complicates the structure and thus the manufacturing and operation of the multilayer film 8, which increases the cost.

Disclosure of Invention

In view of the above, it is an object of the present disclosure to propose a multilayer film having a control button, which can reliably detect intentional actuation of the control button while having a simple structure.

According to the present disclosure, this object is achieved by a multilayer film as defined in paragraph 1, characterized in that a single electrode of the electrodes of the first electrode set constitutes one of the electrodes of a first piezoelectric pressure sensor adapted to detect a pressure exerted on a first area covered by the first electrode set, while the other electrodes of the first electrode set are single electrodes each forming a capacitive touch sensor, each capacitive touch sensor corresponding to a control button.

Indeed, the inventors have observed that it is not necessary to integrate a pressure sensor into each control button to avoid unintended commands. It is sufficient to provide a single pressure sensor for the entire set of control buttons, which can then maintain a simple capacitive sensor. The common pressure sensor allows for the detection of pressure exerted on any control button of the associated group, thereby identifying an intentional command from a user. Providing a single pressure sensor for each set of control buttons simplifies the construction of the multilayer film.

The features disclosed in the following paragraphs may optionally be implemented independently of each other or in combination with each other:

the electrodes of the first electrode set are each located adjacent to each other at the same height in the thickness of the multilayer film;

-the first pressure sensor is a stack comprising said electrodes of the first electrode set, a second electrode and a piezoelectric material sandwiched between the two electrodes;

the multilayer film further comprises a substrate forming the front face, the first electrode set being printed on the substrate, preferably by screen printing;

the multilayer film further comprises a second electrode group covering a second area of the front face, only one of the electrodes of the second electrode group constituting one of the electrodes of a second piezoelectric pressure sensor capable of detecting a pressure exerted on the second area covered by the second electrode group, while the other electrodes of the second electrode group are electrodes each forming a capacitive touch sensor, each capacitive touch sensor corresponding to a control button, the second electrode group being arranged in the same layer as the first electrode group;

-the first piezoelectric pressure sensor and the second piezoelectric pressure sensor are connected in parallel;

the multilayer film further comprises an electrical shield between the electrodes;

-each electrode consists of PEDOT and/or the piezoelectric material of each pressure sensor consists of P (VDF-TrFE);

-the first pressure sensor has the shape of a dot;

the first pressure sensor has the shape of a rectangular rod.

Another object of the present disclosure is a vehicle trim element comprising an interface component defining an outer surface and an opposing surface of the trim element, the trim element further comprising a multilayer film as defined above disposed against the opposing surface of the interface component.

The present disclosure also relates to a method for manufacturing a multilayer film as defined above, comprising the steps of: providing a substrate; printing a first electrode set and, where applicable, a second electrode set onto the substrate; printing a piezoelectric polymer on one of the electrodes of the first electrode set and, where applicable, on one of the electrodes of the second electrode set; printing a second electrode on each deposit of piezoelectric polymer; and polarizing the deposit of each piezoelectric polymer, wherein the printing step is preferably performed by screen printing.

Drawings

Other features, details and advantages will appear upon reading the following detailed description and analyzing the drawings, in which:

fig. 1 is a front view of an automotive dashboard including a multilayer film according to the present disclosure.

Fig. 2 is a front view of a first embodiment of a multilayer film according to the present invention.

Fig. 3 is a rear view of the multilayer film of fig. 2.

Fig. 4 is a cross-sectional view of the multilayer film of fig. 2 and 3 along the plane indicated by arrows IV-IV in fig. 3.

Fig. 5 is a rear view of a second embodiment of a multilayer film according to the present invention.

Fig. 6 to 13 illustrate various steps of the method of manufacturing the multilayer film of fig. 2 to 4.

Detailed Description

Reference is first made to fig. 1. Fig. 1 shows a vehicle trim element, i.e. an instrument panel 1, according to the present disclosure. The present disclosure is also applicable to other decorative elements such as door panels, center consoles, or seats.

Typically, the instrument panel 1 is installed in a passenger compartment of a vehicle (e.g., a motor vehicle). The central portion 7 of the instrument panel 1 is reserved for a plurality of devices, allowing the occupant to act on certain functions of the vehicle. In the example shown, these means comprise a screen 9 and a set button 15. In these devices, there is also a touch interface 16. The touch interface 16 is located on an interface member 18, which is, for example, part of the instrument panel 1. The interface member 18 defines an outer surface 20 and an opposite inner surface (not visible in fig. 1) of the instrument panel 1. The outer surface 20 may be constituted, for example, by a decorative film. By way of example, the interface member 18 may be made of plastic (such as polypropylene or polycarbonate), aluminum, wood, or a flexible skin made of leather or a synthetic material.

The interface member 18, e.g., the outer surface 20, is provided with icons I that indicate to a user the functionality provided by the touch interface 16.

According to the invention, the multilayer film 17 is arranged against an inner surface (not visible in fig. 1) of the interface member 18. In this case it is a multi-layer strip 17 with a plurality of control buttons 19. Each control button 19 is associated with one of the icons I. In icon I, the left is a pair of two pictograms, namely unlocking and closing the padlock. These two pictograms indicate to the user that the corresponding control buttons 19 are an unlock button and a lock button. The seat-shaped icons are also distinguishable, which indicate to the user the corresponding control buttons 19 for adjusting the seat of the vehicle.

Here, the multilayer film 17 is located below the screen 9. Here, the multilayer film 17 is an elongated, substantially rectangular-shaped flexible sheet. However, the multilayer film 17 may have other shapes. Generally, the shape of the multilayer film 17 will follow the shape of the touch interface 16.

Preferably, the multilayer film 17 is attached to the opposite inner surface of the interface member 18, for example using an adhesive. In one variation, the multilayer film 17 is attached to the opposing inner surface by overmolding, for example, during injection molding of the interface member 18. In this alternative form, a mould is provided, the cavity of which is the negative of the interface member 18 to be moulded, the multilayer film 17 being placed in the cavity of the mould together with and opposite the decorative film, and the whole being overmoulded by injecting a plastics material into the cavity. The injected plastic fills the gap between the multilayer film 17 and the decorative film. After molding, the interface member 18 is removed from the mold, the outer surface 20 thereof is constituted by a decorative film, and the opposite inner surface thereof is covered by the multilayer film 17.

The multilayer film 17 is touch-sensitive and pressure-sensitive. Thus, the user can execute the command by pressing one of the control buttons 19 of the multilayer film 17 with their finger (in particular by means of the interface part 18).

The construction of the multilayer film 17 will now be described in more detail with reference to fig. 2 to 4.

The multilayer film 17 has a front face 21 shown in fig. 2 and a back face 23 opposite the front face 21 shown in fig. 3. Preferably, the front face 21 is used to secure the multilayer film 17 to a support, such as the interface component 18.

The front face 21 is provided with a control surface 25. The control surface 25 comprises control buttons 19, in this case control buttons 19.1 to 19.6. The control buttons 19 are distributed along the multilayer film 17, here along the multilayer strip.

In the example shown, two control buttons 19.1 and 19.2 of the first group J1 and four control buttons 19.3 to 19.6 of the second group J2 are distinguished. To indicate to the user that they are two different sets of control buttons, the two sets of control buttons J1 and J2 are separate from each other.

The function associated with each control button 19 is indicated by a respective icon I (pictogram, number or letter) on the interface part 18 of the dashboard 1 (see fig. 1).

The multilayer film 17 includes a main body 27 and a tape 29 attached to the main body 27. More precisely, the body 27 has a first free end 28 and a second end 30 opposite the free end 28, from which a strap 29 extends. The body 27 includes a control surface 25. The tape 29 allows the multilayer film 17 to be connected to vehicle electronics. For this purpose, the belt 29 has a connection terminal portion 32.

Opposite the front face 21 is the back face 23 of the multilayer film 17, which is visible in fig. 3.

The body 27 is provided with a set of eight sensors. More precisely, two pressure sensors 31.1, 31.2 and six capacitive touch sensors 33.1 to 33.6 are distinguishable. Each capacitive touch sensor 33 corresponds to one of the control buttons 19. Two of the capacitive touch sensors (i.e. two capacitive touch sensors 33.1 and 33.2) are located at the free end 28 of the multilayer film 17. The two capacitive touch sensors 33.1 and 33.2 form two control buttons 19.1 and 19.2 of the first set of control buttons J1. The remaining four capacitive touch sensors 33.3 to 33.6 are arranged in a row extending from the middle of the body 27 to the second end 30. The four capacitive touch sensors 33.3 to 33.6 form four control buttons 19.3 to 19.6 of the second set of control buttons J2.

The pressure sensors 31.1 and 31.2 are piezo-electric sensors. The first pressure sensor 31.1 is located at the second end 30 of the body 27, close to the belt 29. The second pressure sensor 31.2 is located between the first set of control buttons J1 and the second set of control buttons J2. Here, the two pressure sensors 31.1 and 31.2 each have a dot shape.

Referring to fig. 4, the layered structure of the multilayer film 17 will now be described. Fig. 4 is a longitudinal section of the multilayer film 17, as indicated by arrows IV-IV in fig. 3.

In the example shown, the multilayer film 17 essentially consists of a stack of five layers. The first layer C1 is a substrate. A second layer C2, which is a layer with a first electrode, is deposited on the substrate C1. The third layer C3 is a piezoelectric layer. Which covers only the two first electrodes of the second layer C2. The fourth layer C4 is a layer of the second electrode. The fourth layer C4 covers only the third piezoelectric layer C3. The fifth, last layer C5 covers all other layers C1 to C4 and constitutes the top of the stack. The last layer C5 is a protective layer made of a dielectric material.

The substrate constituting the first layer C1 is preferably flexible, which means that it is made of a material and dimensioned such that, seen separately, it can deform under its own weight when it is placed on the two supports arranged at its most distal end. Advantageously, the material of the substrate C1 is resistant to temperatures up to at least 140 ℃. In other words, when heated, the substrate C1 retains its original shape at least at a temperature up to 140 ℃.

The second layer C2 of first electrodes comprises five first electrodes 35 of the first set E1 and three first electrodes 35 of the second set E2. In other words, the first electrode group E1 and the second electrode group E2 together share the same layer, i.e., the second layer C2. The first set of first electrodes E1 covers a first zone Z1 of the front face 21. The second group of first electrodes E2 covers a second region Z2 of the front face 21 different from the first region Z1. More specifically, the electrodes of the first group E1 form a row located deep below the front face 21, and the range of the first region Z1 corresponds to the range of the row. Likewise, the electrodes of the second group E2 form another row which is also located deep below the front face 21, and the range of the second region Z2 corresponds to the range of the other row.

Only one electrode 35' of the first electrodes 35 of the first electrode set E1 constitutes one of the electrodes of the first pressure sensor 31.1. The pressure sensor 31.1 is able to detect the pressure exerted on the first zone Z1 covered by the first electrode set E1. The other first electrodes 35 of the first electrode group E1 are only electrodes each forming only one of the capacitive touch sensors 33.3 to 33.6.

Likewise, only one electrode 35' of the first electrodes 35 of the second electrode set E2 constitutes one of the electrodes of the second pressure sensor 31.2. The second pressure sensor 31.2 is able to detect the pressure exerted on the second zone Z2 covered by the second electrode set E2. The other first electrodes 35 of the second electrode set E2 are only electrodes of one of the two capacitive touch sensors 33.1, 33.2 each forming only the first set of control buttons J1.

It should be noted that the detection field of each pressure sensor 31.1 and 31.2 is not strictly limited to the associated zone Z1, Z2. In practice, it is not excluded to detect the pressure exerted on the second zone Z2 with the first pressure sensor 31.1 and vice versa. On the other hand, the corresponding detection signal will be significantly reduced.

It should also be noted that the first electrodes 35 of the first electrode group E1 and the second electrode group E2 are each located adjacent to each other at the same height h in the thickness E of the multilayer film 17.

Here, the first electrode group E1 and the second electrode group E2 are arranged on the back of the substrate C1 at positions forming the front face 21 of the multilayer film 17. Preferably, the first electrode set E1 and the second electrode set E2 are printed on the underside of the substrate C1, in particular by screen printing.

Each pressure sensor 31.1 and 31.2 is here a stack of three levels. The first level corresponds to one electrode 35' of the first electrodes 35. The second level is the piezoelectric material 37 forming part of the third layer C3. The last third level is the second electrode 39, which is part of the fourth layer C4. Thus, in each pressure sensor 31.1 and 31.2, the piezoelectric material 37 is sandwiched between the two electrodes 35' and 39. The layer thickness of the second level of piezoelectric material 37 and thus the thickness of layer C3 is preferably at least 10 μm.

Preferably, all electrodes 35, 39 of the multilayer film 17 are made of a conductive polymer, such as poly (3, 4-ethylenedioxythiophene) or PEDOT. In one variation, some or all of the electrodes 35, 39 may be made of another conductive material, such as silver or carbon.

Preferably, the copolymer P (VDF-TrFE) is chosen to constitute the piezoelectric material 37 of the first and second pressure sensors 31.1, 31.2.

Returning to fig. 2 and 3, a circuit 41 is identified that ensures electrical connection of each of the eight sensors 31, 33 to the belt 29. Preferably, the first pressure sensor 31.1 and the second pressure sensor 31.2 are connected in parallel in order to reduce the number of circuits 41 and to increase the sensitivity to pressure.

More generally, all pressure sensors of a multilayer film according to the present disclosure may be connected in parallel. In this configuration, the multilayer film transmits at its output a single pressure signal that is the result of the single signal generated by the pressure sensor. In other words, all pressure sensors are then connected in a "network" to detect any presses on the control surface 25, regardless of the exact location where the control surface 25 is pressed.

Advantageously, an electrical shield 43 is provided between the first electrodes 35. Here, the electrical shield 43 is in the form of several grid portions that are adjacent to the first electrode 35 without being in electrical contact with the first electrode 35. Preferably, these grid portions 43 are composed of silver wires. The electrical shield 43 prevents false detection of the capacitive touch sensor 33 and reduces spurious noise to which the sensors 31, 33 are exposed.

The multilayer film 17 just described operates as follows: let us assume that the user wants to unlock the functions of their vehicle. To this end, the user presses their finger on the control button 19.1 displaying the unlocking padlock, in particular via the interface member 18. The presence of a user's finger on the control button 19.1 will be detected by the associated capacitive touch sensor 33.1. However, this detection will only take effect if the associated pressure sensor 31.2 detects deformation of the surface of the multilayer film 17 at the same time. Therefore, in order to activate the command, the user needs not only to tap the control button 19.1, but also to exert pressure on it. Thus, undesired commands that may be caused by accidental touches by the user may be avoided. In order to minimize accidental command, a pressure threshold may be provided that needs to be detected by the pressure sensor below which the detection will not take effect.

It should be noted that each pressure sensor 31.1 and 31.2 covers the entire area Z1, Z2 of the multilayer film 17. In fact, in general, pressure sensors, and in particular piezoelectric pressure sensors, are able to detect not only the forces exerted on their own surface, but also in the entire section around their perimeter. In particular, the size of the surrounding section depends on the geometry of the pressure sensor and the stiffness of the multilayer film. Thus, it is sufficient to provide a single pressure sensor to effect actuation of the control buttons as long as the entire set of control buttons remains within the perimeter of the section covered by the pressure sensor.

Thus, in general terms, the number of pressure sensors in the multilayer film may be limited to the minimum required to detect the force applied to any control button of the control surface. It is even possible to connect all such provided pressure sensors in parallel to two common circuits. In this case, in case an applied force is detected, it will not be known which pressure sensors have detected the force. But this information is not necessary for the user command to take effect. Regardless of the exact location, it is sufficient to know that the user is pressing on purpose. This minimization of the number of pressure sensors and the number of circuits simplifies the structure of the multilayer film and thus reduces costs.

Referring to fig. 5, a second embodiment of the multilayer film 17 according to the present disclosure will now be described. The description will be limited to noting the difference of the second multilayer film with respect to the first multilayer film of fig. 2 to 4. For similar elements, please refer to the description above.

The second multilayer film 17 differs in that it includes a single pressure sensor 31. Here, the single pressure sensor 31 has the form of a rectangular bar, whereas in the previous embodiment the two pressure sensors 31.1 and 31.2 have the shape of a dot. The rectangular piezoelectric pressure sensor 31 has an elongated shape that allows it to cover the two sets of control buttons J1 and J2. Thus, by means of the rectangular piezoelectric pressure sensor 31, the pressure exerted at any position on the control surface 25 can be detected. The advantage of this second embodiment over the first embodiment is that the second pressure sensor is omitted. On the other hand, the elongated rectangular geometry of a single pressure sensor 31 is more complex to implement.

According to other embodiments not shown, the pressure sensor may have a polygonal or annular shape, or a "C" or "T" shape.

Referring to fig. 6 to 13, a method of manufacturing the multilayer film 17 of fig. 2 to 4 will now be described.

The first step 100 shown in fig. 6 comprises providing a substrate C1, for example in the form of a strip. Preferably, the substrate is made of poly (ethylene terephthalate) (PET), for example, of thermally stable PET, or of Polycarbonate (PC).

The second step 104 shown in fig. 7 comprises printing the contours 45 of the pressure sensor 31 and the capacitive touch sensor 33 on the back of the substrate C1. These contours 45 are made of a conductive material such as silver. Profile 45 each has contacts 47 for subsequent connection to circuit 41.

A third step 106 is shown in fig. 8. This step comprises printing a first electrode set E1 and a second electrode set E2 on the backside of the substrate C1, in contact with the contour 45 where appropriate. Preferably, the printing is performed with a PEDOT based ink. Thereby obtaining a second layer C2; see fig. 4. This printing step is followed by a drying step (not shown). The drying may, for example, have a duration of 2 to 3 minutes and be carried out at a temperature of about 120 ℃.

As shown in fig. 9, a next step 108 includes printing the piezoelectric polymer 37 onto the first electrode 35' of the future pressure sensor 31. Thereby obtaining layer C3; see fig. 4. This step is followed by a drying step (not shown) again. Drying may be at a temperature of about 120 ℃ for about 15 minutes. Preferably, an annealing step follows, which may last for about 15 minutes at a temperature of about 140 ℃.

Alternatively and not shown, step 108 may be followed by a step of printing a border made of dielectric material around each piezoelectric polymer deposit 37. This dielectric edge reduces the risk of a short circuit being formed between the two electrodes of the pressure sensor 31 during the step 110 of printing the second electrode 39 described below.

In a next step 110, as shown in fig. 10, the second electrode 39 of the future pressure sensor 31 is printed. Again, the use of PEDOT based inks is preferred. Thereby obtaining a fourth layer C4; see fig. 4. Followed by another drying step, preferably at a temperature of about 120 c for 2 to 3 minutes.

Step 110 is followed by a step (not shown) of polarizing the piezoelectric polymer 37. For example, the polarization may be performed using an alternating electric field with a frequency varying from 0.01Hz to 10Hz and a voltage of 100V/micron for a duration of about 5 minutes.

Step 112, see fig. 11, is then performed, which includes printing the conductive circuit 41 and the electrical shield 43 onto the backside of the substrate C1. Preferably, the electrical shield 43 and the electrical circuit 41 are made of silver. The monolith is then preferably dried at a temperature of about 80 ℃ for about 10 minutes (not shown).

In a next step 114, shown in fig. 12, carbon 49 is printed onto the free end of ribbon 29. Carbon 49 protects the ends of circuit 41 from wear. Preferably, this step is followed again by drying (not shown) to about 80 ℃ for about 10 minutes.

In the final step 116, as shown in fig. 13, the entire multilayer film 17 is covered with a dielectric layer except for the terminal connection portions 32 of the tape 29, thereby obtaining a protective layer C5, see fig. 4.

Note that the above-described printing step is preferably performed by screen printing.

The layers of the multilayer film 17 are preferably at least transparent to light having a wavelength between 400nm and 440 nm. The term "transparent" is understood to mean that the light transmission is greater than 80%. This makes it possible to harden the fastening adhesive by light radiation if the multilayer film 17 is attached to the interface member 18 by adhesion.

During fastening of the multilayer film 17 to the instrument panel 1, more particularly to the interface member 18, care should be taken to ensure that the connection between the multilayer film 17 and the interface member 18 is sufficiently strong to prevent any relative movement between the interface member 18 and the pressure sensor 31.

As a variant, the entire batch of multilayer film 17 may be manufactured simultaneously. For this purpose, a large-format sheet is provided, and the surface of the sheet is divided into a plurality of portions corresponding to the number of multilayer films 17 to be produced. Each surface portion then corresponds to the substrate C1 of one of the future multilayer films 17. Then, the above-described printing step is performed for each surface portion of the sheet. The final step involves cutting the printed sheet into as many sheets as there are surface portions. Each sheet thus obtained is actually a multilayer film 17.

Claims (10)

1. A touch-sensitive and pressure-sensitive multilayer film (17), comprising:

a. a front face (21) having a control surface (25) with a plurality of control buttons (19);

b. -a back face (23) opposite to the front face (21); and

c. a first electrode (35) group (E1) covering a first zone (Z1) of the front face (21), the first electrode (35) group (E1) being arranged in a single layer (C2),

characterized in that a single electrode (35') of the electrodes (35) of the first electrode set (E1) constitutes one of the electrodes of a first piezoelectric pressure sensor (31.1) capable of detecting a pressure exerted on the first zone (Z1) covered by the first electrode set (E1), while the other electrodes (35) of the first electrode set (E1) are electrodes each forming a capacitive touch sensor (33), each capacitive touch sensor (33) corresponding to a control button (19).

2. The multilayer film (17) according to the preceding claim, wherein the electrodes (35) of the first electrode group (E1) are each located adjacent to each other at the same height (h) in the thickness (E) of the multilayer film (17).

3. The multilayer film (17) according to any one of the preceding claims, wherein the first pressure sensor (31.1) is a stack comprising the electrodes (35 ') of the first set of electrodes (35) E1), a second electrode (39), and a piezoelectric material (37) interposed between the two electrodes (35', 39).

4. The multilayer film (17) according to any one of the preceding claims, further comprising a substrate (C1) forming the front face (21), the first electrode (35) set (E1) being printed on the substrate (C1), preferably by screen printing.

5. The multilayer film (17) according to any one of the preceding claims, further comprising a second electrode group (E2) covering a second zone (Z2) of the front face (21), only one electrode (35') of the electrodes of the second electrode group (E2) constituting one electrode of the electrodes of a second piezoelectric pressure sensor (31.2) able to detect the pressure exerted on the second zone (Z2) covered by the second electrode group (E2), while the other electrodes (35) of the second electrode group (E2) are electrodes each forming a capacitive touch sensor (33), each capacitive touch sensor (33) corresponding to a control button (19), the second electrode group (E2) being arranged in the same layer (C2) as the first electrode group (E1).

6. The multilayer film (17) according to the preceding claim, wherein the first piezoelectric pressure sensor and the second piezoelectric pressure sensor (31) are connected in parallel.

7. The multilayer film (17) according to any one of the preceding claims, further comprising an electrical shield (43) between the electrodes (35).

8. The multilayer film (17) according to any one of the preceding claims, wherein each electrode (35) is made of PEDOT and/or the piezoelectric material (37) of each pressure sensor (31) consists of P (VDF-TrFE).

9. A vehicle decorative element (1) comprising an interface part (18) defining an outer surface and an opposite surface of the decorative element, the decorative element further comprising a multilayer film (17) according to any one of the preceding claims arranged against the opposite surface of the interface part (18).

10. A method for manufacturing a multilayer film (17) according to any one of claims 1 to 8, wherein the method comprises the steps of:

a. providing a substrate (C1);

b. -printing a first electrode set (E1) and, where applicable, a second electrode set (E2) onto the substrate (C1);

c. printing a piezoelectric polymer (37) on one of the electrodes (35 ') of the first electrode set (E1) and, where applicable, on one of the electrodes (35') of the second electrode set (E2);

d. printing a second electrode (39) on each piezoelectric polymer deposit (37); and

e. each piezoelectric polymer deposit (37) is polarised,

wherein the printing step is preferably performed by screen printing.