Antenna arrangement, external watch part comprising such an antenna arrangement and method for manufacturing such an external watch part

An antenna arrangement (6) for an external watch part (2) of a timepiece. The antenna arrangement is formed of a technical embroidery, which includes an embroidered structure of insulating wires or natural fibres (10) and at least one conductive wire (12) embroidered so as to produce a fine coil integrated in the embroidered structure of insulating wires or natural fibres. The conductive wire is connected to a radiofrequency integrated circuit (8).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to European Patent Application No. 19179728.1 filed Jun. 12, 2019, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD OF THE INVENTION

The invention relates to an antenna arrangement for an external watch part. Such an antenna arrangement can for example allow a bidirectional data communication with other connected electronic objects.

The invention relates likewise to an external watch part comprising such an antenna arrangement and also a method for manufacturing such an external watch part. The external watch part is for example a watch bezel, a watch strap, a watch dial, or even a watch case middle.

The invention relates finally to a timepiece comprising such an external watch part. The timepiece is for example a watch.

STATE OF THE ART

It is known to provide a timepiece, for example a watch, with an antenna connected to an integrated transmission and/or reception circuit. Such an antenna offers thus the timepiece new functionalities allowing communication with its environment. The antenna is in that case typically formed by a solid mono-bloc mass, which is an electrical conductor. Such an antenna arrangement for a watch is for example described in patent EP 1 378 805 B1. The antenna has in that case the form of a ring disposed at the periphery of the middle part of the watch, and the integrated transmission and/or reception circuit is housed in the middle part. The solid mono-bloc mass, forming the antenna, therefore forms at the same time the bezel of the watch.

However, a disadvantage of the antenna arrangement proposed in patent EP 1 378 805 B1 is that it is particularly vulnerable to outside influences, such as for example moisture, mechanical impacts, temperature conditions. Furthermore, this antenna arrangement imposes design modifications upon the parts of the watch, which may impair its aesthetics. Furthermore, the connection with the integrated circuit makes it necessary to pierce the middle part, which makes assembly of the entirety complex. Such an antenna arrangement thus impairs the reliability of the watch.

Other timepiece embodiments comprise an antenna inside the watch case. However, in such embodiments where the antenna is formed of a mono-bloc material, the antenna requires space inside the case because it has a relatively large spatial requirement. This plays a part in increasing the weight of the external watch part, whilst making the construction of the movement more complex.

SUMMARY OF THE INVENTION

The aim of the invention is therefore to provide an antenna arrangement for an external watch part, which is able to be installed inside the part in order to keep it safe from outside influences, whilst being simple to install and not very bulky, and allowing a reliable communication of data with connected electronic objects.

To this end, the invention relates to an antenna arrangement for an external watch part, which comprises the features mentioned in the independent claim1.

A particular form of the antenna arrangement is defined in the dependent claims2and3.

Thanks to the technical embroidery, which forms the antenna arrangement according to the invention, this arrangement can be easily installed within an external watch part. Such a technical embroidery, which is a form developed in two-dimensions for the timepiece and which comprises an embroidered structure of insulating wires or natural fibres and at least one conductive wire embroidered within a fine winding, is in fact in particular not very bulky whilst offering operating reliability for the antenna formed from the conductive wire. Furthermore, such technical embroidery lends itself particularly well to producing external watch parts in a composite material, in particular in a material combining the technical embroidery and a solidified resin, which can be typically a thermosetting resin or an elastomeric resin.

To this end, the invention relates likewise to a method of manufacturing an external watch part comprising the antenna arrangement described above, and which comprises the features mentioned in the independent claim4.

Particular forms of the method are defined in the dependent claims5and6.

To this end, the invention relates likewise to an external watch part comprising the antenna arrangement described above, and which comprises the features mentioned in the independent claim7.

Particular forms of the external watch part are defined in the dependent claims8to13.

According to a particular technical feature of the invention, the external watch part is formed of a flexible structure, in particular a structure made of fabric.

Advantageously, the external watch part is formed of a composite structure comprising the technical embroidery and a solidified resin, and enclosing the radiofrequency integrated circuit. Such a composite structure makes it possible to obtain an external watch part, which is particularly strong and light. Furthermore, the use of such a composite structure makes it possible to obtain a material, which does not form a screen relative to the magnetic and electrical fields of the antenna.

To this end, the invention relates likewise to a timepiece comprising the external watch part described above, and which comprises the features mentioned in the independent claim14.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1represents a watch1provided with an annular bezel2. The annular bezel is mounted on a middle part of the watch, represented in summary in the Figures for reasons of clarity.

The annular bezel2is formed of a composite structure comprising a solidified resin4. As illustrated inFIG. 2, the composite structure comprises in addition a technical embroidery6, and encloses a radiofrequency integrated circuit8for transmission and/or reception. In the particular embodiment example illustrated inFIG. 1, the solidified resin4is a thermosetting resin. The resin4is for example a plastic material resin. In a non-represented variant, the solidified resin4is an elastomeric resin. The resin4is for example rubber.

The technical embroidery6forms an antenna arrangement. The technical embroidery6comprises an embroidered structure of insulating wires or natural fibres10and at least one conductive wire12embroidered so as to produce a fine winding integrated in the embroidered structure of insulating wires or natural fibres10. In the particular embodiment example illustrated inFIG. 2, the technical embroidery6comprises a single conductive wire12. The conductive wire12, which forms the antenna per se, is connected to the radiofrequency integrated circuit8. In a non-represented variant, the technical embroidery6comprises a plurality of conductive wires12. In this case, the conductive wires12form for example a coil of several turns, each of the conductive wires12being connected to the radiofrequency integrated circuit8. Such an embodiment variant is in particular advantageous in the case where the radiofrequency integrated circuit8is an NFC near field communication chip, for example in order to increase the inductance of the antenna so as to adapt in frequency the integrated circuit8by acting on the number of turns.

The conductive wires12can be made of metal or of carbon or of modified silicone for example.

Preferably, the insulating wires10have an electrical resistance, which can be for example greater than 108Ohm·m. In the particular embodiment illustrated inFIG. 2, the insulating wires10are glass fibres. In a non-represented variant, the insulating wires10can be synthetic wires, such as for example wires made of polyamide or of polyester, or even ceramic fibres.

In a variant of the embroidered structure, the natural fibres10can be formed for example of flax or of hemp or of cotton or of a combination of these components.

The radiofrequency integrated circuit8is for example a contactless communication chip. In the particular embodiment ofFIG. 2, the radiofrequency integrated circuit8is an RFID radio-identification chip (from the English Radio Frequency Identification). In a non-represented variant, the radiofrequency integrated circuit8is an NFC near field communication chip or to effect transactions or bank payments.

A method of manufacturing an external watch part comprising the antenna arrangement6according to the invention will now be described with reference toFIG. 3. The external watch part is for example the annular bezel2illustrated inFIGS. 1 and 2. In a non-represented variant, the external watch part can be a watch strap, a watch dial or even a watch case middle.

The method comprises an initial step20in the course of which the technical embroidery6is adjusted in a mould of the external watch part to be produced. In the course of this initial step, the or each conductive wire12of the technical embroidery6is connected to the radiofrequency integrated circuit8, which was previously inserted into the mould.

In the course of a following step22, a resin4is injected into the mould in order to impregnate the technical embroidery6and the radiofrequency integrated circuit8.

In the course of a following step24, the resin4contained in the mould is cured. When the resin4is a thermosetting resin, as in the embodiment example ofFIG. 1, the curing temperature is preferably between 200° C. and 250° C. When the resin4is an elastomeric resin, the curing temperature is preferably substantially equal to 300° C.

In the course of a following step26, the resin4contained in the mould is crosslinked.

In the course of a final step28, the entirety formed of the technical embroidery6, the radiofrequency integrated circuit8and the crosslinked resin4is removed from the mould. Hence the external watch part according to a particular embodiment of the invention is obtained.

Although the invention has been described with reference to an external watch part, in this case, an annular bezel2, formed of a composite structure comprising a solidified resin4, other embodiment variants are possible for the external watch part without departing from the scope of the invention. In particular, the external watch part can be formed of a flexible structure, in particular a structure made of fabric. In this case, the external watch part is typically a watch strap, and no longer comprises solidified resin. According to another embodiment variant, the external watch part is formed from a ceramic base. The external watch part, which is typically a watch bezel, comprises for example a hollow ring made of ceramic, inside which the antenna arrangement6and the integrated circuit8are received. A rubber ring comes therefore to close the hollow ceramic ring, making it possible to obtain the watch bezel.