EP0766152A1 - Timepiece provided with an antenna - Google Patents

Abstract

The antenna (4) is a dielectric with a printed circuit antenna which is either a dipole or a radiating slot. The antenna is housed in a slot (25) between an outer (2) and an inner (5) container. The inner container has a time display (7), and a miniaturised transmitter/receiver (6) connected to the antenna. The radio system is designed to receive and transmit messages.

Description

The present invention relates to a timepiece intended to be worn on the arm or the wrist, said piece comprising either a dipole antenna or a radiating slot antenna capable of picking up and / or emitting an electromagnetic field carrying radio messages, a housing comprising members for displaying the time and a micro transceiver which receives or transmits messages using the antenna.

There are already known timepieces equipped with a dipole antenna and a micro-receiver for picking up radio signals. US Patent 5,317,326 in the name of Motorola, Inc., for example, describes a timepiece in the form of a wristwatch which has a folded dipole antenna housed in the bracelet.

Placing the antenna in the strap of a watch poses problems of connections between the transceiver which is located in the watch case and the antenna which is an integral part of the strap. The passage of conductive elements connecting the antenna to the receiver through the housing therefore poses construction problems which lead to solutions which are never simple. In addition, at the location of this passage, the conductive elements are mechanically stressed almost continuously when the watch is worn and break relatively quickly, if means are not used to avoid this break. These means are moreover expensive and complicate the operation of changing the bracelet, the latter having to be specially made since the bracelet has an antenna and cannot therefore be replaced by a bracelet currently existing on the market.

Attempts have, however, been made to resolve this problem. Thus, the English abstract of document JP-A-52-48364 published in "Patent Abstracts of Japan", vol.1, No. 116, October 4, 1977, page 4486 E 77, describes a timepiece which comprises a microreceptor and an antenna in the case of a watch intended to be worn by a person. This timepiece has two glasses attached to each other. The antenna, of a single-wire type, is interposed between these two windows.

However, placing the antenna in the case of a watch requires the miniaturization of the antenna because of the very limited space which is available for mounting the antenna. If it is possible to reduce to some extent the dimensions of the antenna for a given frequency, it will always be at the expense of its other characteristics, such as gain or bandwidth. At a fixed frequency, a miniature antenna will therefore have a gain and a lower bandwidth than an antenna of normal size placed in the bracelet.

Thus, the object of the present invention is to provide a timepiece of the type defined above which overcomes the drawbacks of the prior art.

The invention also aims to provide such a timepiece whose antenna as such and its electrical dimensions are optimized.

In addition, the invention aims to provide such a timepiece in which the construction of the antenna and its mounting in the housing are simple. This construction is also compact.

To this end, the subject of the invention is a timepiece intended to be worn on the wrist, the piece comprising either a dipole antenna or a radiating slot antenna capable of picking up and / or emitting an electromagnetic field carrying messages radio stations, a first box comprising members for displaying the time and a micro transceiver which receives or transmits messages using the antenna. The timepiece is characterized by the fact that it further comprises a second case intended to receive the first case so that the external surface of the first case and the inner surface of the second housing define a mounting groove, in that the antenna comprises a dielectric substrate and at least one conductive element in printed circuit fixed on the substrate and which defines a radiating element of said antenna and in that the antenna is located in the mounting groove so that it is wrapped around the first housing.

Thanks to this combination of characteristics, the antenna can, on the one hand, be manufactured independently of the other elements of the timepiece. On the other hand, the antenna can be easily housed in this timepiece during its assembly so as to take advantage of the inherent dimensions of the timepiece to optimize the electrical dimensions of the antenna.

According to one embodiment of the invention, the timepiece further comprises a ground plane located in the mounting groove, between the antenna and the exterior surface of the first housing so that it surrounds this housing.

Thus, it is possible to electrically isolate the antenna from the disturbing elements which is located inside the timepiece.

• la figure 1 montre un poignet portant une pièce d'horlogerie selon la présente invention;
• la figure 2 est une vue en plan de la pièce d'horlogerie de la figure 1;
• la figure 3 est une vue en plan d'un premier mode de réalisation d'une antenne faisant partie de la pièce d'horlogerie de la figure 1;
• la figure 4 est une vue en plan d'un deuxième mode de réalisation d'une antenne faisant partie de la pièce d'horlogerie de la figure 1;
• la figure 5 est en vue en coupe de la pièce horlogerie de la figure 2;
• la figure 6 est une vue en perspective de l'antenne de la figure 3 enroulée autour du premier boîtier de la pièce d'horlogerie de la figure 5;
• la figure 7 est une vue en plan d'un troisième mode de réalisation de l'antenne faisant partie de la pièce horlogerie de la figure 2;
• la figure 8 est une vue en perspective de l'antenne de la figure 6 enroulée autour du premier boîtier de la pièce d'horlogerie de la figure 5; et,
• la figure 9 est une vue en plan d'un quatrième mode de réalisation de l'antenne faisant partie de la pièce horlogerie de la figure 2.

Other characteristics and advantages of the invention will appear more clearly on reading the detailed description which follows, taken with reference to the appended drawings, representing, by way of example, different embodiments of the timepiece of the invention and in which:

• Figure 1 shows a wrist carrying a timepiece according to the present invention;
• Figure 2 is a plan view of the timepiece of Figure 1;
• Figure 3 is a plan view of a first embodiment of an antenna forming part of the timepiece of Figure 1;
• Figure 4 is a plan view of a second embodiment of an antenna forming part of the timepiece of Figure 1;
• Figure 5 is a sectional view of the timepiece of Figure 2;
• Figure 6 is a perspective view of the antenna of Figure 3 wound around the first case of the timepiece of Figure 5;
• Figure 7 is a plan view of a third embodiment of the antenna forming part of the timepiece of Figure 2;
• Figure 8 is a perspective view of the antenna of Figure 6 wound around the first case of the timepiece of Figure 5; and,
• FIG. 9 is a plan view of a fourth embodiment of the antenna forming part of the timepiece of FIG. 2.

FIG. 1 schematically represents an forearm carrying a wristwatch 1 comprising a box 2 and a bracelet 3. To pick up an electromagnetic field carrying radio messages, the box 2 contains an antenna 4.

Figure 2 is a plan view of the wristwatch 1 comprising the housing 2, the bracelet 3 and the antenna 4. The wristwatch 1 further comprises an additional housing 5, which is disposed in the housing 2. A micro transceiver 6 is arranged in the housing 5 in addition to the time display members comprising in particular a movement 7, a dial 8, hands 9 and a supply battery 10. The micro transceiver 6 is connected to the antenna 4 so that it receives or transmits messages using the latter and then transforms these messages into data perceptible by the wearer of the wristwatch 1, for example, by emitting sound signals.

Referring now to FIG. 3, it can be seen that the antenna 4 comprises conductive elements in circuit prints 11 and 12 fixed on a dielectric substrate 13. In addition, to facilitate the assembly of the antenna in the timepiece of the invention, the substrate 13 is preferably flexible. For example, it has been determined that commercially available Kapton® and Espanex® materials are suitable in this regard.

, où λ est la longueur d'onde du signal électromagnétique que l'antenne est destinée à capter ou à émettre. L'élément conducteur 12 forme un bras de compensation qui est rajouté à ce dipôle. La longueur du bras est réglée de sorte que l'impédance de l'antenne est adaptée à une ligne de transmission qui relie l'antenne 1 au micro émetteur-récepteur 6 disposé dans le boîtier de la pièce d'horlogerie de l'invention.The conductive element 11 defines a dipole. Preferably, this dipole has a length of approximately $\frac{\text{<figure-callout id="2" label="λ" filenames="imgf0001.png,imgf0003.png" state="{{state}}">λ</figure-callout>}}{\text{2}}$

, where λ is the wavelength of the electromagnetic signal that the antenna is intended to receive or transmit. The conductive element 12 forms a compensation arm which is added to this dipole. The length of the arm is adjusted so that the impedance of the antenna is adapted to a transmission line which connects the antenna 1 to the micro transceiver 6 disposed in the case of the timepiece of the invention.

The connection between the antenna 4 and this transmission line is assigned to two excitation points 14 and 15, respectively at mid-length of the conductive element 11 and on the conductive element 12. The conductive elements 11 and 12 are preferably formed by metallic deposits, for example, of copper, on the dielectric substrate 13.

FIG. 4 shows a variant of the antenna of FIG. 3. It can be seen in this figure that the antenna 16 comprises conductive elements in printed circuit 17.1 and 17.2 fixed on a dielectric substrate 18.

. L'élément conducteur 17.2 forme un bras de compensation qui est rajouté à ce dipôle. Une armature d'un condensateur 19 est reliée avec le bout de l'élément conducteur 17.2 de manière à former avec ce dernier une connexion d'adaptation gamma entre le dipôle 17.1 et la ligne de transmission qui relie l'antenne 1 au microrécepteur 6. La connexion entre l'antenne 16 et la ligne de transmission est affectée à deux points d'excitation, respectivement à mi-longueur de l'élément conducteur 17.1 et l'autre armature du condensateur 19.The conductive element 17.1 forms a dipole. Preferably, this dipole has a length of approximately $\frac{\text{<figure-callout id="2" label="λ" filenames="imgf0001.png,imgf0003.png" state="{{state}}">λ</figure-callout>}}{\text{2}}$

. The conductive element 17.2 forms a compensation arm which is added to this dipole. An armature of a capacitor 19 is connected with the end of the conducting element 17.2 so as to form with the latter a gamma adaptation connection between the dipole 17.1 and the transmission line which connects the antenna 1 to the microreceptor 6. The connection between antenna 16 and the transmission line is assigned to two excitation points, respectively at mid-length of the conducting element 17.1 and the other armature of the capacitor 19.

Figure 5 is a sectional view of the wristwatch 1. The timepiece 1 includes the dipole antenna 4 of Figure 3 as well as the two cases 2 and 5, the clockwork movement 7, the microreceptor 6 and the power supply battery 10 of FIG. 2. The timepiece 1 also comprises a printed circuit board 20 mounted in the housing 5, a crystal 21, a base 22 and a transmission line 23. The micro transmitter- receiver 6 is mounted on the printed circuit board 20. The micro transceiver 6 and the movement 7 are supplied by the portable energy source 10.

The housing 2 is intended to receive the housing 5 so that the exterior surface of the housing 5 and the interior surface of the housing 2 define a mounting groove 25. As can be seen in FIG. 6, the antenna 4 is located in the mounting groove 25 so that it wraps around the housing 5.

The arrangement which has just been described makes it possible to manufacture the antenna independently of the other elements of the timepiece. This facilitates the manufacture not only of the antenna but also of the timepiece as such.

In addition, this arrangement facilitates the housing of the antenna during its assembly in the timepiece so as to take advantage of the inherent dimensions of the latter and to be able to optimize the electrical dimensions of the antenna.

Preferably, and as can be seen in FIGS. 3, 4 and 5, the surface of the conductive elements 11 and 12 extend in the direction of the depth of the wristwatch 1, namely in the direction between its crystal and its background. However, the optimization of the antenna 4 is linked to this surface. The depth of a wristwatch is a dimension that can be relatively easily changed without significantly affecting either its visual appearance or the ease of use. Thus, the arrangement of the antenna in this way makes it possible to facilitate the optimization of the antenna in a wristwatch.

The antenna 4 is excited using the transmission line 23 which connects the antenna 4 to the microreceptor 6. The transmission line 23 is preferably made up of a microstrip track. As an alternative, this transmission line could also consist of a coaxial cable.

Preferably, the transmission line 23 passes through an opening 26 formed in the side wall of the housing 5. By bringing the microreceptor 6 closer to the antenna 4, this arrangement makes it possible to minimize the length of the transmission line 23 and thus minimize losses due to it.

The wristwatch 1 could also include a ground plane 24. The ground plane 24 is located in the mounting groove 25 between the antenna 4 and the outer surface of the housing 5 so that it surrounds the latter. The ground plane 24 has the advantage of electrically isolating the antenna 4 from the disturbing elements which are inside the wristwatch 1, for example, metallic masses such as the movement 7, the microreceptor 6 and the power supply battery 10. Thus, the characteristics of the antenna 4 can be selected without considering the disturbing effects originating from the interior of the wristwatch 1. One of the advantages of such an arrangement is that it allows the use of the same antenna with various watch movements.

FIG. 7 shows a third embodiment of the antenna of the timepiece of the invention. This antenna 30 consists of a printed circuit conducting element 31 fixed on a dielectric substrate 32. As described above, the substrate 32 is preferably made of a flexible material. The element conductor 31 is preferably produced by a metallic deposit on the dielectric substrate 32.

, où λ est la longueur d'onde du signal électromagnétique que l'antenne est destinée capter.A radiating slit 33 is formed in the conductive element 31. A person skilled in the art knows that, according to the Babinet principle, this antenna is the dual of a conventional dipole antenna, such as the dipole formed by the conductive element 11 Thus, the radiating slot 33 forms the complement of a dipole. Preferably, the slot has a length of about $\frac{\text{<figure-callout id="2" label="λ" filenames="imgf0001.png,imgf0003.png" state="{{state}}">λ</figure-callout>}}{\text{2}}$

, where λ is the wavelength of the electromagnetic signal that the antenna is intended to receive.

The connection between the antenna 30 and the transmission line 23 is assigned at two excitation points 34 and 35, respectively at mid-length and at opposite sides of the radiating slot 33. If necessary, the adaptation of the antenna 30 at the impedance of the transmission line 23 can be done using a capacitor connected between one of the excitation points and one of the conductors of the transmission line 23.

As can be seen in FIG. 8, the antenna 30 is also located in the mounting groove 25 so that it is wound around the housing 5.

FIG. 8 shows a fourth embodiment of the antenna of the timepiece of the invention. Like the antenna 30, the antenna 40 consists of a conductive element 41 fixed to a dielectric substrate 42. The latter is preferably made of a flexible material. The conductive element 41 is preferably produced by a metallic deposit on the substrate 32, and defined by, a radiating slot 43 is formed in the ground plane 41. While the slot 33 is rectilinear, the slot 43 of the Figure 6 has the shape of a "V".

The connection between the antenna 40 and the transmission line 23 is assigned at two excitation points 44 and 45 at opposite sides of the point of the "V" of the radiating slot 43. The adaptation of the antenna 40 to the impedance of the transmission line 23 could also be done using a capacitor connected between one of the excitation points and a wire of the transmission line 23. Such a form of slot makes it possible to position the excitation points 44 and 45 in the direction of the depth of the wristwatch 1 so that they are opposite the microreceptor 6. Thus, the length of the transmission line which connects the antenna 40 to the microreceptor 6 can be minimized.

Finally, it should be noted that several modifications and / or improvements can be made to the object identification system according to the invention without departing from the scope thereof.

Claims (6)

Timepiece likely to be worn on the wrist, said piece comprising:
either a dipole antenna (4) or a radiating slot antenna (30; 40) capable of picking up and / or emitting an electromagnetic field carrying radio messages, and a first housing (5) comprising - organs (7,8,10) for displaying the time, and - a micro transceiver (6) which receives or transmits messages picked up by the antenna (4; 30; 40), characterized in that it further comprises - a second housing (2) intended to receive said first housing (5) so that the exterior surface of said first housing and the interior surface of said second housing define a mounting groove (25), in that said antenna (4; 30; 40) comprises - a dielectric substrate (13; 33; 43), and - at least one conductive element in printed circuit (11,12; 31; 41) fixed on said substrate (13; 33; 43) and which defines a radiating element of said antenna (4; 30; 40), and in that said antenna (4; 30; 40) is arranged in said mounting groove (25) so that it is wound around said first housing (5). Timepiece according to claim 1, characterized in that it further comprises - a ground plane (24) located in said mounting groove between said antenna and the outer surface of said first housing so that it surrounds the latter. Timepiece according to any one of claims 1 or 2, characterized in that said dielectric substrate (13; 33; 43) consists of a flexible material. Timepiece according to any one of the preceding claims, characterized in that the surface of said conductive elements extends in the direction of the depth of said piece. Timepiece according to any one of the preceding claims, characterized in that it further comprises
a transmission line (23) which connects said antenna (4; 30; 40) to said micro transceiver (6), in that said first housing (5) has an opening in its side wall, said transmission line (23 ) passing through said opening (26) to allow the approximation of said antenna (4; 30; 40) of said micro transceiver (5). Timepiece according to claim 5, characterized in that said antenna (16) consists of two conductive elements (17.1,17.2) and a capacitor (19) connected to a first of said conductive elements so as to form an adaptive connection gamma between the second of said conductive elements and said transmission line (23).

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