Antenna device for clock

Abstract

The present application discloses an antenna device (1) intended for use in a communication system of a clock, comprising: a substrate (10); a first antenna circuit (11) formed on the substrate and having a first wiring harness (110) and a second wiring harness (111) connected thereto, the first wiring harness and the second wiring harness having a proximal end and a distal end and extending in parallel; a second antenna circuit (12) formed on the substrate (10) and having a third wiring harness (120) and a fourth wiring harness (121) connected thereto, the third wiring harness (120) and the fourth wiring harness (121) having a proximal end and a distal end and extending in parallel; an electrical connection link (13) connecting the proximal ends of the first wiring harness and the third wiring harness; and a connecting portion (100) configured to bend relative to the electrical connection link and comprising a conductive connection device connected to the electrical connection link (13) and an electromagnetic shielding device for the conductive connection device.

Description

Technical Field

[0001] The present invention relates to an antenna device for use in a communication system for a timepiece. Background Art

[0002] For many years, watches have been integrated devices for communication, so as to be able to connect to different communication networks (such as Bluetooth to mobile terminals) and to geolocation networks to be connected to different satellite positioning systems such as GPS, Glonass or Galileo. For this purpose, watches have integrated one or more antennas.

[0003] It is known that the optimal size of an antenna depends directly on the wavelength of the transmitted / received signal. An antenna of optimal length allows the signal to be transmitted / received at full power overall.

[0004] In a watch, the available space is limited and the antenna must be of a design suitable for fitting into the middle part of the watch.

[0005] If the watch incorporates a radio communication device operating at a radio frequency (eg 2.4 GHz or 1.5 GHz), the size of the product relative to the wavelength (120 mm and 200 mm) becomes critical.

[0006] Additionally, other constraints must be considered:

[0007] - A watch comprises many metal parts, especially its middle part, and the antenna must be insulated from them.

[0008] - A watch can integrate in the same case several communication devices, as specified above. A watch cannot have a volume exceeding certain dimensions (as a general rule, a maximum diameter of 50 mm). Summary of the Invention

[0009] The object of the present invention is to provide an antenna device intended for use in a communication system of a timepiece such as a watch, which antenna device integrates at least two antenna circuits, each antenna circuit having an optimal length to transmit / receive signals as a whole at full power and suitable for being accommodated in the middle part of a watch with limited volume.

[0010] This objective is achieved by producing a miniature multi-band, single-radiating structure that exploits the properties of nearby materials (metal intermediate components, sapphire crystal). This integration is made possible by separating physical integration (construction) and antenna form thanks to printing technologies (e.g., flexible PCBs). This multi-band structure is connected to the electronics via a suppression filter-type circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Other features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the following drawings:

[0012] - Figure 1 represents an antenna device according to the present invention;

[0013] - Figure 2 A partial cross-sectional view showing a timepiece incorporating an antenna device according to the present invention;

[0014] - Figure 3 showing a graph illustrating the gain seen by each frequency band employed in the communication system of the present invention, and

[0015] - Figure 4 A diagram showing the isolation principle of the frequency band allowed by the antenna device of the present invention is shown. DETAILED DESCRIPTION

[0016] In the rest of the description, the terms "top", "bottom", "upper", "lower", "above", "below" should be considered to take into account a horizontal mid-plane (P) parallel to the horizontal bearing plane of the case of the timepiece on the surface.

[0017] The terms "exterior", "outer", "inner" and "inner" should be understood as taking into account a median axis (X) oriented perpendicular to said median plane.

[0018] The present invention relates to an antenna device intended for use in a communication system to be integrated into the case of a timepiece, in particular a wristwatch or even a connected wristwatch or a connected wristwatch.

[0019] Reference Figure 2 The watch case 4 comprises a housing volume delimited by a middle part 40, typically made of a metallic material, forming side walls around the central axis, this middle part 40 being made in a single part or in two parts with an upper bezel 41, for example made of ceramic or titanium. The housing volume of this watch 4 is closed from above by a crystal 42, for example made of sapphire crystal, supported by the middle part 40 and sealingly secured thereto by suitable means. The watch also comprises a back cover (not visible), for example made of metal, situated opposite the crystal 42 relative to the central plane, advantageously separated from the middle part by a seal, closing the volume from the bottom.

[0020] According to a particular aspect of the invention, the timepiece 4 comprises a communication system comprising:

[0021] - a communication antenna device 1, and

[0022] - A duplexer / rejection filter circuit 20, known per se to a person skilled in the art.

[0023] The antenna device 1 comprises a substrate 10 which is advantageously made in the form of a flexible printed circuit (commonly referred to as "flex").

[0024] Reference Figure 1 , the antenna device 1 has the characteristic of comprising two different antenna circuits to allow the timepiece to be connected to two different networks, more specifically to a Bluetooth type communication network and a GNSS (Geographic Positioning and Navigation Satellite System) satellite positioning network, such as GPS (Global Positioning System), Glonass or Galileo.

[0025] The two antenna circuits are fabricated on the same substrate by standard methods used in the field of printed circuits.

[0026] According to certain aspects of the invention:

[0027] - the first antenna circuit 11 has a first wire bundle 110 and a second wire bundle 111, each wire bundle including a proximal end and a distal end and extending in parallel between its proximal end and distal end, the first and second wire bundles being connected 112 at their proximal ends and separated at their distal ends;

[0028] - the second antenna circuit 12 has a third wiring harness 120 and a fourth wiring harness 121, each of the third wiring harness 120 and the fourth wiring harness 121 including a proximal end and a distal end, and the third wiring harness 120 and the fourth wiring harness 121 extending in parallel between their proximal and distal ends, the third wiring harness 122 and the fourth wiring harness 122 being connected at their distal ends and separated at their proximal ends;

[0029] The electrical link 13 allows the proximal ends of the first harness 110, the second harness 111 and the third harness 120 to be connected. This electrical link 13 comprises a single connection point 130 to which the filter circuit 2 is connected. The single connection point 130 will thus allow communication by selectively using the first antenna circuit 11 and the second antenna circuit 12.

[0030] The architecture of two parallel strands of the first antenna circuit 11 allows widening the frequency band (100 MHz) required for communication (2.4 GHz), for example, on a Bluetooth type communication network.

[0031] For the second antenna circuit 12 (for example dedicated to satellite positioning circuitry), the antenna is powered at the current node and its length is folded, allowing for improved impedance matching.

[0032] The single connection point 130 for the two parallel antenna circuits 11, 12 allows for improved mechanical integration of the antenna arrangement within the housing volume of the timepiece 4, as well as improved design independence between the antenna and electronics components. In practice, it is sufficient to adjust the mechanical integration of the support plate of these antenna circuits during construction, followed by the patterning of the antenna circuits using standard etching methods, which do not require any compromise in terms of mechanical integration. The second antenna circuit 12, with its two wires connected in series, allows for communication in a narrower frequency band, such as 1.5 GHz, for example, for communication on satellite positioning networks (such as GPS).

[0033] In this configuration, each antenna circuit 11 , 12 extends substantially along a circular arc trajectory, since it comprises two wire bundles 110 , 111 , 120 , 121 arranged in parallel on the substrate 10 following this path.

[0034] As an example, each antenna circuit 11, 12 can be formed at an angle between 70° and 80° on either side of the electrical connection link relative to the angular sector defining the arc formed by the antenna circuits 11, 12. Their trajectory can follow this arc formed along a radius between 16 mm and 22 mm. The two wire bundles 110, 111, 120, 121 can be spaced apart by a distance of 1 mm to 2 mm.

[0035] Substrate 10 is in the form of a first plate having a profile formed in the shape of a circular arc—advantageously, a semicircle. This configuration is particularly useful for achieving circular polarization for satellite antennas. Due to wave propagation in enclosed spaces such as living spaces, this configuration also facilitates the implementation of the Bluetooth protocol. The two antenna circuits are printed on the same side of the plate, for example, its top surface, and each extends on either side of a separator carrying electrical connections 13 connecting the two antenna circuits 11 and 12. This separator is advantageously located in the middle, thereby dividing the substrate into two circular arcs of substantially equal, or even equal, or strictly equal, dimensions.

[0036] The antenna device further comprises a connecting portion 100 in the form of a protrusion of a plate.

[0037] During integration of base 10 into middle part 40 of timepiece 4 , connection 100 of base 10 is intended to bend relative to the first plate about an axis perpendicular to axis (X) and parallel to plane (P).

[0038] This connection portion 100 comprises one or more electrically conductive connection means allowing the antenna circuits 11, 12 to be connected (at the electrical connection 13) to the electronic control circuit 2 carrying the duplexer / rejection filter circuit 20. The connection portion 100 comprises electromagnetic shielding means for these electrically conductive connection means, so as to prevent any radiation to the outside and to prevent the connection portion 100 from affecting the impedance of the antenna circuits 11 and 12. Thus, by way of example, the shielding can be achieved by assembling several superimposed layers: a shielding lower layer, an insulator layer, a layer containing the electrically conductive connection means, then a new insulator layer and a new shielding upper layer.

[0039] A control card carrying electronic control circuit 2 (control circuit 2 carrying, for example, one or more RF transmitting / receiving circuits, the design of which is known per se) may be arranged at the bottom of the case of timepiece 4 .

[0040] The antenna device 1 is connected to the control card via the connection portion 100 via conductive connection device(s).

[0041] Reference Figure 2 The timepiece 4 may include a dial 43, advantageously made of metal, located above the back cover in its housing. This dial may have an aesthetic appearance visible through the crystal of the timepiece. It may advantageously have a disc-like shape.

[0042] The timepiece may comprise a wedge 44 arranged on the dial. This wedge 44 defines a horizontal support plane and is intended to support the substrate 10 carrying the antenna circuit. This wedge may have a circular or semicircular shape and defines a constant thickness determined above the dial.

[0043] The base 10 of the antenna device 1 is arranged to be positioned on the wedge 44 with its first plate resting on the bearing plane formed by the wedge. The connecting portion 100 of the base 10 is bent to be positioned vertically along a plane transverse to the midplane (P).

[0044] A first wedge-shaped element 45 , for example made of insulating foam, may be positioned between the base and the bezel covering the middle part.

[0045] A second element 46 , for example made of insulating plastic and shaped like a semi-ring, comprises an upper portion abutting against the top surface of the base 10 , a vertical portion extending downwards to the dial, and a lower portion abutting against the dial.

[0046] A touch screen 47 , for example of the capacitive type, can be fastened below crystal 42 to the main part of its surface, separated from said second element 46 by air.

[0047] To secure the bracelet, the timepiece comprises two horns 48 on either side of its middle part, each horn being arranged to secure a different strand of the bracelet.

[0048] The antenna arrangement is multi-band to operate at least two communication circuits having different characteristics in terms of frequency, polarization, gain and impedance.

[0049] For impedance, the electronic control circuit 2 may include a radio frequency duplexer / rejection filter 20 .

[0050] As regards gain and polarization, the mode of each antenna circuit 11 , 12 allows managing these parameters.

[0051] The use of a duplexer / rejection filter allows for the isolation / insulation of two communication circuits (eg, Bluetooth and GPS).

[0052] As an example, it should be noted that a Bluetooth type communication circuit requires linear polarization, whereas a GPS type communication circuit requires circular polarization. The GPS system in particular applies a polarization known as left polarization.

[0053] Furthermore, the solution of the invention takes into account the fact that timepiece 4 comprises a middle part 40 made of metallic material.

[0054] According to a particular aspect of the invention, the antenna device 1 is intended to be placed as high as possible in the case of the timepiece, that is to say as close as possible to the window, while remaining hidden from the eyes of the user.

[0055] Furthermore, the arrangement of antenna device 1 in the case of the timepiece allows it to benefit from its metal middle part 40, through which it can emit its radiation. In order not to impair the radiation, particularly in the lateral direction, the addition of a bezel 41 made of a ceramic-type material with a high dielectric constant allows the electrical length of the antenna to be increased, thus improving its efficiency relative to its physical dimensions.

[0056] The antenna device 1 is placed above a dial 43, also metallic, benefiting from a volume above the antenna device that is mainly filled with air (thereby increasing the efficiency of the antenna). This metallic dial 43 also acts as a screen, partially modifying any construction below the dial, which is transparent relative to the antenna device 1.

[0057] Figure 3 The diagram illustrates the performance of a communication system using the present invention in terms of gain, presented by each of the frequency bands, the ISM band (Industrial, Scientific and Medical - corresponding to the band used by networks such as Bluetooth) and the GNSS band (geopositioning and navigation by satellite systems).

[0058] Figure 4 Two curves are shown which illustrate the separation of frequency bands allowed by using the antenna arrangement according to the invention. It can be seen that the ISM band is well separated from the GNSS band.

[0059] It goes without saying that the present invention is not limited to the embodiments described above and that various modifications and simple variations may be considered by a person skilled in the art without departing from the scope of the invention as defined in the appended claims.

Claims

1. An antenna device (1) for a communication system of a clock, characterized in that The antenna device comprises: - a substrate (10); a first antenna circuit (11), the first antenna circuit being formed on the substrate and having a first wire bundle (110) and a second wire bundle (111), the first wire bundle and the second wire bundle having a proximal end and a distal end and extending in parallel between the proximal end and the distal end, the first wire bundle and the second wire bundle being connected at the proximal end and separated at the distal end; - a second antenna circuit (12), the second antenna circuit being formed on the substrate (10) and having a third wire bundle (120) and a fourth wire bundle (121), the third wire bundle and the fourth wire bundle having a proximal end and a distal end and extending in parallel between the proximal end and the distal end thereof, the third wire bundle and the fourth wire bundle being connected at their distal ends and separated at their proximal ends; - an electrical junction link (13) connecting the proximal ends of the first and third wiring harnesses; and - a connecting portion (100) configured to bend relative to the electrical connection link and comprising an electrically conductive connection device connected to the electrical connection link (13), and an electromagnetic shielding portion of the electrically conductive connection device.

2. The antenna device (1) according to claim 1, characterized in that The wire harness (110, 111, 120, 121) is curved.

3. The antenna device (1) according to claim 1 or 2, characterized in that The substrate (10) is a flexible plastic substrate.

4. The antenna device (1) according to claim 1 or 2, characterized in that The base (10) is composed of a first plate having a surface on which two antenna circuits are formed, and the connecting portion (100) is configured to be bent relative to the first plate.

5. The antenna device (1) according to claim 4, characterized in that The first plate of the base has an arc-shaped profile.

6. The antenna device (1) according to claim 1 or 2, characterized in that The first antenna circuit (11) and the second antenna circuit (12) are arranged on both sides of the electrical connection link (13).

7. A remote communication system for a timepiece, comprising: - an antenna device (1) as defined in one of claims 1 to 6, - a duplexer / suppression circuit (20) connected to said electrical junction link via the electrically conductive connection means of said connection portion (100).

8. The telecommunication system according to claim 7, wherein: The duplexer / suppressor circuit (20) includes a first communication circuit configured to communicate according to a Bluetooth type protocol and a second communication circuit configured to communicate over a satellite positioning network via first and second antenna circuits, respectively.

9. A timepiece (4), comprising a case formed by a middle part (40), an upper mirror (41) and a back cover, characterized in that: The timepiece comprises a flange and a telecommunication system as claimed in claim 7 or 8, the substrate (10) being arranged in the flange of the timepiece.

10. The timepiece (4) according to claim 9, comprising an upper crystal, wherein the first antenna circuit (11) and the second antenna circuit (12) are arranged opposite to the upper crystal (41) of the timepiece.

11. The timepiece (4) according to claim 9 or 10, characterized in that The timepiece comprises a metal dial (43) placed in a case of the timepiece, and the antenna device (1) is arranged above the metal dial.

12. The timepiece (4) according to claim 11, characterized in that The duplexer / suppression circuit (20) is arranged below the metal dial (43).

13. The timepiece (4) according to claim 9 or 10, characterized in that The timepiece is a connected wristwatch.

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