AU9821198A

AU9821198A - A door handle and a transponder system

Info

Publication number: AU9821198A
Application number: AU98211/98A
Authority: AU
Inventors: Slava Tihovsky
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1998-03-16
Filing date: 1998-12-24
Publication date: 1999-09-30
Anticipated expiration: 2018-12-24
Also published as: EP0943764B1; AU742683B2; EP0943764A1; DE59909928D1

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

r Name of Applicant: ROBERT BOSCH GmbH of Postfach 30 02 20, D-70442 Stuttgart, Germany Actual Inventor(s): Address for Service: Invention Title: DAVIES COLLISON CAVE, Patent Attorneys, of 1 Little Collins Street, Melbourne, Victoria 3000, Australia "A DOOR HANDLE AND A TRANSPONDER SYSTEM" Details of Associated Provisional Application No: PP2348/98 The following statement is a full description of this invention, including the best method of performing it known to us: P:\OPER\DBW\PP2348.98 24/12/98 -2- A DOOR HANDLE AND A TRANSPONDER SYSTEM The present invention relates to a door handle of a vehicle, and a transponder system.

Passive entry systems have been developed for vehicles where authorised persons can gain access to a vehicle simply by bringing an electronic key within a predetermined distance of the vehicle. The electronic key, which may be a smart card or similar device, normally includes a transponder which within the predetermined distance can be or is excited by the 10 electronic system of the vehicle. The electronic system includes a transponder transceiver system which is designed to generate a magnetic field to excite the transponder of the key.

The transceiver and key are then able to communicate to exchange security codes which can .be used to determine whether entry should be allowed to the vehicle for a person carrying the key.

The transceivers include coil antennas, and in particular may comprise a dual coil antenna. Dual coil antennas, which are also referred to as twin loop antennas, are used to generate the magnetic field for exciting the transponder of the key. The two coils are S o.

0. i configured and driven so as to produce a rotating elliptically polarised field which can excite a transponder held at different orientations. The range of the field is normally about 1 metre.

o: The two antennas have in the past been placed in a transceiver housing which is located either in a bumper of a vehicle, or a door rear vision mirror assembly. Both of these locations however have proved undesirable to vehicle manufacturers. Both the bumper and the door mirror assembly represent parts of a vehicle which are more frequently subject to damage than any other parts. Accordingly, manufacturers are reluctant to place important vehicle electronic components in these locations. The most desirable location for the antennas is one which a person wishing to enter the vehicle would normally approach on entry, as the transponder would be brought into closer proximity with the antennas. The door mirror assembly, and particularly the vehicle bumper, are not vehicle parts which a person normally approaches on trying to enter a vehicle.

P:\OPER\DBW\PP2348.98 24/12/98 -3- In accordance with the present invention there is provided a door handle of a vehicle, said door handle having two coil antennas of a transponder system of the vehicle.

Advantageously, the antennas can be used to produce a magnetic field for exciting a transponder of a key. Preferably the magnetic field is a rotating elliptically polarised field.

Preferably one antenna includes an air core and a flat coil, and the other antenna includes a magnetic material core. Preferably the other antenna has a ferrite core. Preferably the ferrite core has two ferrite rods.

The present invention also provides a transponder system for a vehicle including a dual coil transceiver with two antennas in a door handle of the vehicle.

Preferred embodiments of the present invention are hereinafter described, by way of example only, with reference to the accompanying drawings, wherein: *"Figure 1 is a plan view of a door handle part of a first preferred embodiment; *Figure 2 is a cross-sectional view A-A of the part of Figure 1; "Figure 3 is a cross-sectional view B-B of the part of Figure 1; Figure 4 is a circuit diagram of a transceiver of the first preferred embodiment; Figure 5 is a plan view of a door handle part of a second preferred embodiment; .Figure 6 is a cross-sectional view A-A of the part of Figure Figure 6 is a cross-sectional view A-A of the part of Figure o• Figure 7 is a cross-sectional view B-B of the part of Figure 5; Figure 8 is a circuit diagram of a transceiver of the second preferred embodiment; and Figure 9 is a schematic partial perspective view of the door handle part.

A door handle 2, as shown in Figures 1 to 3, includes a first end 4 with a pin receiving jaw 6, about which the handle 2 is able to pivot when affixed to a vehicle. A second end 8 of the handle 2 includes a stop rest 10 which normally abuts the adjacent vehicle door when the handle 2 is not being pivoted. Between the two ends 4 and 8 is a central grip portion 12 which is designed to allow a person's hand to grip the portion 12 in order to pivot the door handle P:\OPER\DBW\PP2348.98 24/12/98 4- 2 and open the vehicle door. The grip portion 12 is hollowed out or recessed so as to provide a hollow space 14 along the length of the portion 12. The hollow space 14 is used to house components of a transceiver of a transponder system of the vehicle. The transponder system forms part of a passive vehicle entry system of the vehicle. The components are sealed within the hollow space 14, and a covering lid of the grip portion 12 is not shown in the Figures.

The components housed within the grip portion 12 include two antennas 20 and 22 of the transceiver. The first antenna 20 is an air core antenna with a multi-turn flat wire coil 24 fitted or printed on a bottom surface 26 in the hollow space 14. The coil 24 may be printed i 10 on foil or a PCB. Attached to the coil 24 is a capacitor 28 of the antenna 20, and the capacitor 28 is used to tune the resistance and inductance of the coil 24 to resonance. The second antenna 22 comprises a multi-turn wire coil 30 which is looped around two ferrite rods 32, as shown in Figure 9. The wire coil 30 is connected to the output of an antenna driver circuit 33 of the transceiver 34, as shown in Figure 4.

The ferrite core 32 of the antenna 22 overlaps the first antenna 20 by a distance 36 which is selected to provide maximum magnetic coupling between the two antennas when the second antenna 22 is driven by the transceiver 34. The second antenna 22 is therefore used :i to excite the first antenna 20, which is selected to resonate using the tuning capacitor 28 so as to again enhance the magnetic coupling, or mutual inductance between the two antennas S 20 and 22.

To produce a rotating elliptically polarised magnetic field for exciting a transponder of the transponder system, the magnetic fields generated by the two antennas 20 and 22 need to be substantially perpendicular, and there also needs to be a 900 phase shift between the two currents carried by the coils 30 and 24 of the antennas. The physical relationship between the two coils 30 and 24, ensures their respective magnetic fields are substantially perpendicular, and the 90' phase change is introduced by the magnetic coupling or mutual inductance of the two antennas 20 and 22, and the resonant circuit provided by the first antenna 20. The range of the magnetic field produced by the antennas 20 and 22 is about 1 to 2 metres. The magnetic P:\OPERDBW\PP2348.98 24/12/98 field rotates in synchronism with the cycle of the currents in the antennas.

The provision of the ferrite rods 32 enables the size of the second antenna 22 to be significantly reduced without any decrease in the magnetic flux generated, thereby allowing perpendicular magnetic fields to be generated within the confines of the grip portion 12 of the door handle 2.

To increase the range of the antennas 20 and 22 further, losses incurred by the magnetic coupling between the antennas 20 and 22 can be alleviated by driving the antennas 10 separately and no longer having the antennas magnetically coupled. This is achieved in the second door handle 40 shown in Figures 5 to 7. The handle 40 is the same as the first handle 12, except it has the second antenna 22 positioned directly in the centre of and above the first S. antenna 42 so as to ensure there is minimal coupling between the magnetic fields generated by the two antennas 22 and 42. The first antenna 42 is also different in that it no longer includes the tuning capacitor 28 and is driven by a second antenna driver of a dual driver circuit 44 of the transceiver 46, as shown in Figure 8. The arrangement of the antennas 22 and 42 are still such that the fields generated are substantially perpendicular with respect to one another. To generate the 90' phase difference between the currents in the coils 24 and the two drivers of the dual driver circuit 44 generate drive currents which are 900 out of phase. Placing the second antenna 22 directly above the first antenna 42 also allows the size of the hollow space 14 in the grip portion 12 to be reduced.

The door handles 2 and 4 are described above as only incorporating the two antennas of the transceivers 34 and 46, but the handles can also be designed so as to incorporate additional electronic components of the transceivers 34 and 46, and even the entire components of the transceivers, as these remaining components occupy minimal space compared to the antennas.

A door handle, particularly the front driver's door handle, is normally approached on trying to enter a vehicle and for this reason represents a particularly desirable location for the P:\OPER\DBW\PP2348.98 24/12/98 -6twin loop antennas. The door handle is also a considerably more robust component than the door mirror assembly or vehicle bumper. A door handle however provides only minimal space for including a dual antenna assembly, but the configurations of the above handles are able to overcome this difficulty.

Many modifications will be apparent to those skilled in the art without departing from the scope of the present invention as herein described with reference to the accompanying drawings.

1.

Claims

1. A door handle of a vehicle, said door handle having two coil antennas of a transponder system of the vehicle.

2. A door handle as claimed in claim 1, wherein said antennas are adapted to produce a magnetic field for exciting a transponder of a key of the vehicle.

3. A door handle as claimed in claim 2, wherein said magnetic field is a rotating 10 elliptically polarised field.

4. A door handle as claimed in claim 3, wherein a first antenna of said antennas has an air core and a flat multi-turn coil, and a second antenna of said antennas has a magnetic material core and a multi-turn coil wound around said magnetic material core.

5. A door handle as claimed in claim 4, wherein said magnetic material core is a ferrite core.

6. A door handle as claimed in claim 5, wherein said ferrite core has two ferrite rods.

7. A door handle as claimed in claim 1, including two ends and a central grip portion between the two ends, said grip portion including a region for incorporating said antennas.

8. A door handle as claimed in claim 7, wherein said handle incorporates driver circuitry connected to said antennas.

9. A door handle as claimed in claim 8, incorporating a transceiver of the transponder system, said transceiver including said driver circuitry. *4 V *5

54.. P:\OPER\DBW\PP2348.98 24/12/98 -8- A door handle as claimed in any one of the preceding claims, wherein the coils of the antennas are arranged to overlap one another to enhance the magnetic coupling therebetween, and said door handle includes driver circuitry adapted to drive one of the antennas, which in turn excites the other one of the antennas. 11. A door handle as claimed in claim 10, wherein said other antenna includes a resonant circuit adapted to enhance said magnetic coupling. 12. A door handle as claimed in any one of claims 1 to 9, wherein said coils of said 10 antennas are positioned to reduce magnetic coupling between the antennas, and said door handle includes driver circuitry adapted to generate respective drive signals for said antennas. o 13. A door handle substantially as hereinbefore described with reference to the accompanying drawings. 14. A transponder system for a vehicle including a dual coil transceiver with two antennas in a door handle as claimed in any one of the preceding claims. 15. A vehicle having a door handle as claimed in any one of the preceding claims. S*S DATED this 24th day of December, 1998 ROBERT BOSCH GmbH By its Patent Attorneys DAVIES COLLISON CAVE