WO2004100390A1

WO2004100390A1 - Apparatus for shielding a radio communications device device

Info

Publication number: WO2004100390A1
Application number: PCT/IB2004/001450
Authority: WO
Inventors: Kevin R. Boyle
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2003-05-09
Filing date: 2004-04-28
Publication date: 2004-11-18
Also published as: GB0310656D0

Abstract

A radio communications device (10) comprising a radio frequency (RF) circuitry (14) and an antenna (12) combination accommodated by a module (11) and further comprising a portion of attached mechanically flexible electrically conductive sheet material (30) arrangeable such that during use said sheet material functions as a shield to RF radiation emanating from said combination. The device allows most or all aspects of RF communication to be performed between devices in a personal area network while shielding the wearer from RF radiation.

Description

DESCRIPTION

APPARATUS FOR SHIELDING A RADIO COMMUNICATIONS DEVICE

The present invention relates to a radio communications device, in particular a device for use in personal area networks on or around the body.

The so-called personal area network (PAN) or body area network (BAN) consists of a number of devices worn on or about the users body, usually accommodated within clothing or accessories. Such devices may be connected to each other to form a network by wired connections. JP2000- 064112 describes a garment having a number of pockets for accommodating electronic equipment and electrical wiring between those pockets for establishing electrical connection between devices. However, wireless connections between devices are preferred if wires are likely to hinder a wearers actions or require a user to route wires. In any case an appropriate interface will be required between devices to establish connection. The presence of wires can also cause problems during the manufacture of garments or the like that are to carry devices of a user. Furthermore it may not be possible to incorporate wires in a garment or accessory without detracting from the look or feel of that garment or accessory.

The devices may be of a number of types, for example mobile telecommunications devices, audio/visual entertainment devices, personal organisers, wearable computing apparatus and so forth. However, other types of device include sensors to make biometric measurements of a wearers body such as temperature and heart rate and environmental sensors to measure the temperature and light level of a wearers surroundings. Clearly there are advantages if these devices can be connected to each other to enhance functionality.

To perform wireless connections between these devices radio frequency (RF) communications equipment is required. However, it is usually beyond the normal skills and resources of the textile or apparel manufacturing industry to assemble RF communications equipment or to embed antennas into equipment ready for connecting RF circuitry to. Furthermore, if RF energy transmitted by RF equipment is absorbed by a wearers body, that absorbed energy is wasted for the purposes of communicating between devices.

In accordance with the present invention there is provided a radio communications device comprising a radio frequency (RF) circuitry and an antenna combination accommodated by a module and further comprising a portion of attached mechanically flexible electrically conductive sheet material arrangeable such that during use said sheet material functions as a shield to RF radiation emanating from said combination.

Such an arrangement provides an efficient body mounted antenna obviating the need to route radio frequency cables around the body between RF communications antennas and circuitry and apparatus such as a sensor or other user device which relies upon the RF communications antenna and circuitry for communication with other apparatus.

Because coupling between the RF circuitry and associated antenna is already complete, this aspect need not concern the designer. The portion of electrically conductive sheet material is arrangeable to shield the wearers body during use from RF energy emitted from the RF circuitry and antenna combination, thereby reducing the amount of energy that is otherwise lost in the body.

By including as much of the RF and base band circuitry as possible in a small relatively low profile package, the device may be incorporated in garments and accessories whilst being unobtrusive or un-noticeable.

The device offers a modular solution to aspects of RF communications allowing the designer to attach a device to a given piece of equipment (user equipment, sensors, actuators or the like) thus permitting the equipment to communicate by an RF link to other equipment.

The device may be encapsulated to provide environmental protection. These and other aspects of the present invention appear in the appended claims to which the reader is now referred and which are incorporated herein by reference.

The present invention will now be described with reference to the figures of the accompanying drawings in which:

Figure 1 is a plan view of an embodiment of a radio communications device made in accordance with the present invention;

Figure 2 is a cross-sectional view of the embodiment taken along the line A-A of Figure 1 ; and

Figure 3 is a schematic block view of a module employed in the embodiment showing the base-band circuitry, radio frequency (RF) circuitry and an antenna.

It should be noted that the drawings are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of the Figures have been shown exaggerated or reduced in size for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar features in the different embodiments.

An embodiment of a radio communications device 10 includes a module

1 1 which accommodates an antenna 12 coupled by coupling 13 to radio frequency (RF) circuitry 14 to facilitate transmission and / or reception operations using said antenna. Preferably the antenna 12 is a notch antenna or a slot antenna. The modular device 11 is further provided with base-band circuitry 16 connected to the RF circuitry 14 by connection 15. The base band circuitry 16 includes an interface 17 thus providing inputs and outputs 18 to the base band circuitry 14 so that the base band circuitry can be connected to other apparatus, circuitry or devices as will be appreciated by the person skilled in the art. The inputs and outputs 18 can convey control information, data information or a combination thereof. The module 11 is mounted on a flexible substrate 20 which is provided with a number of contact pads 21 electrically connected to the inputs and outputs 18 by conductors 22.

Contact pads 21 at a first end facilitate the connection of other apparatus, circuitry or devices to inputs and outputs 18 of baseband circuitry interface 17. The contact pads may be located on the same side of the substrate 20 as module 11 or on the other side of substrate 20, in which latter case substrate 20 has means for establishing electrical connections from one side of the substrate to the other, as will be appreciated by the person skilled in the art. Instead of or in addition to contact pads 21, substrate 20 may be equipped with one or more electrical connector (not shown) having contacts which are electrically connected to inputs and outputs 18 of baseband circuitry interface 17. By use of a complementary mating electrical connector, further apparatus, circuitry or devices may communicate with the inputs and outputs 18 of baseband circuitry interface 17, as will be appreciated by the person skilled in the art.

A portion of flexible electrically conductive sheet material 30 is attached at a first end to the substrate 20 to extend therefrom, the sheet material being folded in a region 31 distanced from the module to double back on itself such that a second end is located underneath the module 20 and first end of the sheet material to provide two substantially parallel planes of material provided by two portions 30a and 30b respectively which are separated from each other by a separation distance denoted by reference numeral 32. The two portions are maintained in separated location by interposed spacing material 40 which is dielectric. The sheet material 30 may be attached to substrate 20 by adhesive, heat bonding or a stitching process using thread (as is possible in the garment construction industry).

A number of spacing materials 40 are suitable as will be appreciated by the person skilled in the art but examples include air filled foam, cotton, plastics material, rubber, textile or other suitable synthetic or natural insulative material. The flexible electrically conductive sheet material 30 may be metal foil, metal coated insulating sheeting, a laminate including metal foil, metal coated sheet material, or sheet material having conductive material deposited thereon, for example conductive ink. The conductive sheet 30 may be of fabric that is woven, knitted or non-woven, such as felt; in these cases the fabric is provided with at least a proportion of electrically conductive material - alternatively or in addition the sheet 30 may have electrically conductive material deposited thereon. Two examples of conductive material include metal or conductive ink. The flexible electrically conductive sheet material 30 may be of rubber or other such non-conductive material having conductive metal elements distributed therein - in such cases the sheet material may exhibit poor electrical conductivity when measured at d.c. but at radio frequencies will appear to be conductive.

The portion 30b of sheet material 30 that is doubled back underneath the module acts as to absorb and / or reflect radio frequency energy emitted by the antenna 12 and RF circuitry 14 combination. Consequently, the portion 30b acts as a shield to reduce the RF energy present on the side of the sheet material remote from the antenna 12 and RF circuitry 14 combination in comparison to the situation where the portion 30b is absent. During use this portion 30b shields the wearer from the emitted RF energy.

The sheet material 30 is coupled to the ground plane of the slot or notch antenna 12 by virtue of portion 30a being coupled to the ground plane. Under some operational requirements it may be permissible to electrically disconnect portion 30b from 30a whilst still achieving satisfactory shielding by portion 30b. Electrical disconnection may be achieved by including an portion of electrically insulating material between portions 30a and 30b in the location of the fold of sheet 30 denoted by reference numeral 31. Alternatively, if the sheet material 30 is made electrically conductive by virtue of having electrically conductive ink deposited on it, the disconnection may be achieved by an absence of electrically conductive ink in the vicinity of 31. Alternatively, if the sheet material is made electrically conductive by virtue of being produced from knitted or woven textile containing conductive material, the knit or weave may be altered locally in the vicinity of 31 to be devoid of such conductive material. The module 11 may be attached to flexible substrate 20 by adhesive. The module 11 may be attached to flexible substrate by establishment of electrical and physical connections, such as by a soldering process; these connections may be surface mount connections. Alternatively or in addition these connections may be formed by leads extending from the base of the module through the substrate to its surface remote from the module where solder connections are made to the substrate. The module may be provided with a plurality of connections on its underside for connection to the substrate by solder connections (surface mount or using leads extending through the substrate). Such connections serve to establish a good mechanical connection between the module and substrate. One or more of the module connections may be coupled to the ground plane of the antenna 12. The substrate 20 is preferably mechanically flexible but may instead be rigid. However it is preferable that a rigid substrate 20 is physically smaller than the flexible equivalent so as to maintain a discrete and unobtrusive presence of the device. An example of rigid substrate material is epoxy fibreglass laminate (FR4). The antenna 12, radio frequency circuitry 14 and base band circuitry 16 and interface 17 of the module 11 may be formed on low temperature cold fired ceramic (LTCC).

The module may be encapsulated to provide environmental protection. The module and substrate may be encapsulated to provide environmental protection which will also serve to protect the connections between the module and substrate. If required, the module, substrate and connections to the sheet material 30 may be encapsulated for protection. Such encapsulation will protect the device during use, for example from moisture, rain or during washing. The module and substrate combined may be produced in a size of around 15 mm long, 12 mm wide and 2mm high or even smaller, although this is just a guideline. The RF and antenna may operate according to the so-called Bluetooth, Zigbee or 802.11 a/b/c/d/e standards, as will be appreciated by the person skilled in the art. In the case where operation at 2.4GHz is required a notch antenna 12 is approximately 20mm long, but the notch may be of a shape other than a straight line in order to conserve space.

In summary, the device provides for an efficient body mountable antenna with no need for RF cables or connection between such cables to be made by the user or during use of the device by a designer. The flexible substrate 20 and sheet material 30 may be an integral component of one or more type of material. Apparatus may be connected to the device of the present invention via the device interface connections 18; such connections may also carry power. The sheet material 30 is size optimised to provide efficient radiation from the module at the frequency concerned in the required direction. No RF transmission lines are required, which are practically difficult to manufacture in such a way that they can withstand repeated wishing. Sensitive parts can be completely encapsulated in resin etc.

From reading the present disclosure other modifications will be apparent to persons skilled in the art. Such modifications may include other features which are already known in the design, manufacture and use of radio frequency antennas, RF circuitry, shielding, electronic circuitry and associated manufacture and construction techniques and applications thereof and which may be used instead of or in addition to features already described herein.

Claims

1. A radio communications device comprising radio frequency (RF) circuitry (14) and an antenna (12) combination accommodated by a module (11) and further comprising a portion of attached mechanically flexible electrically conductive sheet material (30) arrangeable such that during use said sheet material functions as a shield to RF radiation emanating from said combination.

2. A device according to claim 1 wherein said sheet material (30) is attached to said module (11) directly.

3. A device according to claim 1 wherein said module (11) is mounted on a flexible substrate (20) and said sheet material (30) is attached to said flexible substrate.

4. A device according to claim 1 wherein said module (11) is formed on a flexible substrate (20) and said sheet material (30) is attached to said flexible substrate.

5. A device according to claim 3 or 4 wherein said sheet material (30) is provided in the form of an extension of the flexible substrate.

6. A device according to any one of claims 1 to 5 wherein said combination further comprises base-band circuitry (16) coupled to the RF circuitry (14) and the base band circuitry (16) is provided with an interface (17) having at least one of an input or output connection (18).

7. A device arrangement according to claim 6 when appended to claim 3, 4 or 5 wherein at the interface (17) at least one connection is provided on said flexible substrate.

8. A device arrangement according to any one of claims 1 to 7 wherein said antenna (12) is a notch antenna or a slot antenna.

9. A device arrangement according to any one of claims 1 to 8 wherein said antenna (12) and RF circuitry (14) are provided on the same substrate

(20).

10. A device arrangement according to any one of claims 1 to 9 wherein said the combination is encapsulated to provide environmental protection.

11. A device arrangement according to any one of claims 1 to 10 wherein said sheet material (30) is of metallic foil, metal coated sheet material, knitted woven or non-woven textile fabric that includes at least a proportion of conductive material, knitted woven or non-woven textile fabric having conductive material deposited thereon or electrolessly plated rip stop nylon.