Trim element for a motor vehicle seat

Abstract

The invention relates to a trim element (1) for a motor vehicle seat, comprising: an elastically compressible padding block (2); a flexible trim cover (3) covering the block; a capacitive sensor (4) arranged on the underside of the cover, the sensor being made from printed conductive ink; a printed circuit (5) connected to the sensor by a flexible support strip (6) receiving a printed conductive ink (7), the support strip being made from an electrically insulating material, the strip having a first end portion (8) attached on the underside of the cover facing the sensor, the first end portion being extended by an extended portion (9) separated from the cover, the extended portion ending in a second end portion (10) connected to the printed circuit, the strip passing through the block via a slot (11) provided in the block.

Description

[0001] DESCRIPTION

[0002] Title: Automotive seat trim component

[0003] The invention relates to a seat upholstery element for a motor vehicle.

[0004] Document EP-4 399 124 describes the production of a trim element – ​​such as a headrest, armrest, or seat or backrest padding – for a motor vehicle seat comprising:

[0005] • a block of elastically compressible padding,

[0006] • a flexible covering cap covering said block,

[0007] • a capacitive sensor disposed on the underside of said cap, said sensor being based on printed conductive ink,

[0008] • a user finger reception area located on said headgear opposite said sensor, so as to allow tactile activation of said sensor by a user finger, in order to trigger the actuation of an electrical system attached to said trim element,

[0009] • a printed circuit board connected to said sensor by a flexible support strip receiving printed conductive ink, in order to allow programmed action of said system by said printed circuit board.

[0010] According to the known design, the support band is made from the material of the headgear.

[0011] As a reminder, a capacitive sensor creates an electrostatic field that varies in the presence of an object with electrical capacitance, such as a user's finger. In the presence of this object, the electrostatic field changes, and the sensor's capacitance also changes—relative to a predefined value that can be adjusted to regulate the sensor's sensitivity. This change in the sensor's capacitance is then detected by a printed circuit board (PCB) to trigger a programmed action. A PCB includes an insulating substrate, generally a rigid or flexible board, that holds and electrically connects a set of electronic components to create a complex electronic circuit. It is also known as a circuit board.

[0012] An electrical system such as the one mentioned above is for example a loudspeaker, a heating mat, a lighting system or a geared motor allowing the upholstery element to be operated to place it in a comfortable position.

[0013] It is also worth noting that printed conductive ink typically consists of a plastic matrix in which conductive particles are dispersed – for example, particles made of silver, copper, gold, carbon, or a conductive polymer. Printing with such ink is notably done using screen printing.

[0014] However, several disadvantages can result from such an arrangement:

[0015] • A support strip made from the same material as the cap can be very expensive, due to the cost of the material used to make the cap itself. • The support strip can be quite long, which can induce electrostatic disturbances that may affect the uniformity of the associated electrostatic field, and therefore the sensitivity of the sensor and the repeatability of its operation through capacitive effects.

[0016] • In addition, the presence of seams crossing the conductive ink can lead to the appearance of "hot spots", linked to the localized decrease in the conductive cross-section at the level of said seams, which can lead to an electrical malfunction.

[0017] The invention aims to overcome these drawbacks.

[0018] To this end, the invention proposes a vehicle seat upholstery element comprising: • an elastically compressible padding block,

[0019] • a flexible covering cap covering said block,

[0020] • a capacitive sensor disposed on the underside of said cap, said sensor being based on printed conductive ink,

[0021] • a user finger reception area located on said headgear opposite said sensor, so as to allow tactile activation of said sensor by a user finger, in order to trigger the actuation of an electrical system attached to said trim element,

[0022] • a printed circuit board connected to said sensor by a flexible support strip receiving printed conductive ink, in order to allow programmed action of said system by said printed circuit board,

[0023] said element also having the following characteristics:

[0024] • said support strip is made of an electrically insulating material, • said strip has a first extreme portion fixed to the underside of said cap opposite said sensor, said first extreme portion extending into an extended portion detached from said cap, said extended portion ending in a second extreme portion connected to said printed circuit board,

[0025] • said strip passes through said block via a slot provided in said block.

[0026] With the proposed layout:

[0027] • Since the support band is not made from the same material as the cap, there is no shortage of inexpensive materials to use in its production, which has a favorable impact in terms of cost.

[0028] • We will see later that the length of the support strip can be minimized, which is favorable to the proper functioning of the sensor,

[0029] • Furthermore, it will also be seen that it is possible to eliminate seams passing through the conductive ink, thus optimizing electrical operation. Other features and advantages of the invention will become apparent in the following description, made with reference to the accompanying figures, in which:

[0030] [Fig.1] is a schematic representation in partial cross-section of an element according to one embodiment,

[0031] [Fig. 2] is a schematic partial cross-sectional representation of an element according to an alternative embodiment, said figure showing only a detail area illustrating the difference in arrangement with the embodiment of figure 1.

[0032] With reference to the figures, a motor vehicle seat upholstery element 1 is described, comprising:

[0033] • a block 2 of elastically compressible padding,

[0034] • a soft-covering cap 3 - for example made of leather or fabric which may be provided with a soft foam comfort underlayer - covering said block,

[0035] • a capacitive sensor 4 disposed on the underside of said cap, said sensor being based on printed conductive ink,

[0036] • a receiving area 12 for a user's finger arranged in a location on said headgear opposite said sensor, so as to allow tactile activation of said sensor by a user's finger, in order to trigger the actuation of an electrical system attached to said trim element,

[0037] • a printed circuit board 5 connected to said sensor by a flexible support strip 6 receiving printed conductive ink, in order to allow programmed action of said system by said printed circuit board,

[0038] said element also having the following characteristics:

[0039] • said support strip is based on an electrically insulating material, • said strip has a first extreme part 8 fixed on the reverse of said cap opposite said sensor, said first extreme part extending into an extended part 9 detached from said cap, said extended part ending in a second extreme part 10 connected to said printed circuit, said strip passes through said block through a slot 11 provided in said block.

[0040] According to an embodiment not shown, the receiving area 12 of a user's finger has a circular shape.

[0041] According to one embodiment, the reception area 12 of a user's finger has a surface area between 50 and 150 mm 2 , being notably between 70 and 100 mm 2 .

[0042] According to one design, the support strip 6 has a thickness of less than 1 mm, so as not to be perceptible by sight or touch.

[0043] According to one embodiment, the band 6 extends perpendicularly to the cap 3 in the area receiving the sensor 4.

[0044] Such an arrangement prevents the sensor 4 from being activated by the band 6 if a seat occupant leans on it; in addition, the length of said band is minimized.

[0045] According to the embodiment shown in Figure 1, the ink 7 of the sensor 4 is printed onto the support strip 6.

[0046] According to an alternative embodiment shown in figure 2, the ink 7 of the sensor 4 is printed on the reverse side of the cap 3.

[0047] In this case, to ensure good contact between the sensor 4 and the strip 6, it can be provided that the said strip is first fixed to the underside of the cap 3 - in particular by fusion or gluing - the conductive ink 7 is then printed on the underside of said cap in the area of ​​sensor 4 and on said strip, all in a single step, which ensures the expected conductive continuity. According to one embodiment, the second extreme part 10 is connected to the printed circuit 5 by crimping.

[0048] Such an arrangement avoids a weld causing a hard spot; in addition, better control of the electric field is ensured because the conductive mass is unchanged, the implementation of a controlled electric field making it possible to optimize the operation according to a capacitive principle.

[0049] According to various embodiments, the first extreme part 8 is fixed to the underside of the cap 3 by fusion or by means of an adhesive.

[0050] In particular, the strip 6 is in the form of a thermoplastic film, said strip comprising a support layer and a welding layer, said welding layer having a lower melting temperature - being for example between 105 and 115°C - than that of said support layer - being for example between 150 and 170°C.

[0051] With such an arrangement, the fixing of the band 6 is achieved by welding carried out by melting the weld layer.

[0052] According to one embodiment, the welding and support layers are both based on thermoplastic polyurethane (TPU), which ensures good weldability, and also insensitivity to steam which can be used to smooth out the headgear during the manufacture of the trim element.

[0053] According to other designs, the welding and support layers are both based on polyester, polypropylene, polyethylene or ethylene-vinyl acetate (EVA).

[0054] In an alternative embodiment, the strip 6 is made of fibrous material – for example, fabric or non-woven material. In this case, the strip 6 can be provided with a pressure-sensitive adhesive backing. Alternatively, the strip 6 can be provided with a fusible backing attached by welding. It is advisable to ensure that the strip 6 has sufficient tensile strength to prevent excessive elongation, so as not to significantly impact the circuit length and also to prevent breakage.

[0055] As an example, a TPU with an elongation at break of between 400 and 450% and a tensile strength of between 30 and 25 MPa can be used (measured according to the ISO 527-1 standard in force at the date of filing of the application, on samples with a thickness of between 20 and 30 microns and a width of 50mm).

[0056] According to an embodiment not shown, it is possible to cover the sensor 4 with a thermoplastic film laminated on its reverse side, in order to protect it against moisture and / or abrasion and / or to avoid its contact with metallic parts which may be present in the structure of the packing element 1.

[0057] In a way not shown, it is possible to provide a visual and / or tactile marking - for example by hot pressing - allowing a user to identify the position of the sensor 4 under the cover 3.

[0058] Finally, it is noted that since band 6 is not made from the material of headdress 3, said band is not at risk of being crossed by seams made in said headdress which could lead to the appearance of "hot spots".

Claims

DEMANDS 1. Element (1) of motor vehicle seat upholstery comprising: • a block (2) of elastically compressible padding, • a flexible covering (3) covering said block, • a capacitive sensor (4) disposed on the underside of said cap, said sensor being based on printed conductive ink, • a receiving area (12) for a user's finger arranged in a location on said headgear opposite said sensor, so as to allow tactile activation of said sensor by a user's finger, in order to trigger the actuation of an electrical system attached to said trim element, • a printed circuit board (5) connected to said sensor by a flexible support strip (6) receiving printed conductive ink, in order to allow programmed action of said system by said printed circuit board, said element being characterized in that: • said support strip is based on an electrically insulating material, • said strip has a first extreme part (8) fixed to the underside of said cap opposite said sensor, said first extreme part extending into an extended part (9) detached from said cap, said extended part ending in a second extreme part (10) connected to said printed circuit board, • said strip passes through said block by a slot (11) provided in said block.

2. Element (1) according to claim 1, characterized in that the band (6) extends perpendicularly to the cap (3) in the area receiving the sensor (4).

3. Element (1) according to claim 1 or 2, characterized in that the ink (7) of the sensor (4) is printed on the support strip (6).

4. Element (1) according to claim 1 or 2, characterized in that the ink (7) of the sensor (4) is printed on the reverse side of the cap (3).

5. Element (1) according to any one of the preceding claims, characterized in that the second extreme part (10) is connected to the printed circuit board (5) by crimping.

6. Element (1) according to any one of the preceding claims, characterized in that the first extreme part (8) is fixed to the underside of the cap (3) by fusion or by means of an adhesive.

7. Element (1) according to claim 6, characterized in that the strip (6) is in the form of a thermoplastic film, said strip comprising a support layer and a welding layer, said welding layer having a lower melting temperature than said support layer.

8. Element (1) according to claim 7, characterized in that the welding and support layers are both based on thermoplastic polyurethane.

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