U.S. patent application number 09/843474 was filed with the patent office on 2002-01-03 for vehicle exterior mirror with antenna.
Invention is credited to Duroux, Bernard.
Application Number | 20020000942 09/843474 |
Document ID | / |
Family ID | 10839266 |
Filed Date | 2002-01-03 |
United States Patent
Application |
20020000942 |
Kind Code |
A1 |
Duroux, Bernard |
January 3, 2002 |
Vehicle exterior mirror with antenna
Abstract
An exterior rear view mirror for a motor vehicle comprises a
case containing a reflective member and an antenna, consisting of
an electrically conductive layer on a surface of the case, for
transmitting and/or receiving radio frequency electromagnetic
radiation. The electrically conductive layer has at least one zone
having its periphery shaped in accordance with the frequency of
said electromagnetic radiation.
Inventors: |
Duroux, Bernard;
(Garancieres, FR) |
Correspondence
Address: |
H. Duane Switzer
Jones, Day, Reavis & Pogue
North Point
901 Lakeside Avenue
Cleveland
OH
44114-1190
US
|
Family ID: |
10839266 |
Appl. No.: |
09/843474 |
Filed: |
April 26, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09843474 |
Apr 26, 2001 |
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09404101 |
Sep 23, 1999 |
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6259412 |
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Current U.S.
Class: |
343/713 ;
343/711 |
Current CPC
Class: |
B60R 2001/1261 20130101;
B60R 1/12 20130101 |
Class at
Publication: |
343/713 ;
343/711 |
International
Class: |
H01Q 001/32 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 1998 |
GB |
9820622.0 |
Claims
1. An exterior rear view mirror for a motor vehicle comprising a
case containing a reflective member and an antenna for transmitting
and/or receiving radio frequency electromagnetic radiation
comprising an electrically conductive layer on a surface of the
case, characterized in that the electrically conductive layer
comprises a first zone having its periphery shaped in accordance
with the frequency of said electromagnetic radiation.
2. A rear view mirror according to claim 1, wherein the length of
said first zone is substantially equal to about three tenths of the
wavelength of said electromagnetic radiation.
3. A rear view mirror according to claim 2, wherein said first zone
is formed on a curved part of the surface of the case so as to form
a part-conical antenna, the half cone angle .theta. of which is
related to the length .left brkt-bot., the feed-point impedance Zo
and the wavelength .lambda. by the formula:(Zo/.pi.)Ln Cot
g.theta./2=1500(.left brkt-bot./.lambda.)-113,3
4. A rear view mirror according to claim 1, wherein the
electrically conductive layer comprises a further zone for
receiving electromagnetic radiation of a frequency different from
that received by said first zone.
5. A rear view mirror according to claim 1, wherein the
electrically conductive layer is located on the inside surface of
the case.
6. A rear view mirror according to claim 1, wherein the case has an
exterior cover member and the electrically conductive layer is
applied to the inner surface of said exterior cover member.
7. A rear view mirror according to claim 1, wherein the case has an
exterior cover member and the conductive layer is located on a part
of the outer surface of the mirror case, which is enclosed by the
cover member.
8. A rear view mirror according to claim 1, wherein the
electrically conductive layer comprises foil secured by
adhesive.
9. A rear view mirror according to claim 1, wherein the
electrically conductive layer comprises an insert moulding formed
as part of one of the case and the cover member.
10. A rear view mirror according to claim 1, wherein the case is
formed as co-moulding of two different plastics material, only one
of which is capable of accepting surface metallisation, and the
conductive layer comprises metallisation deposited thereon.
11. A rear view mirror according to claim 1, wherein the
electrically conductive mirror comprises first and second zones
which are shaped so that the first zone is a mirror image of the
second zone.
12. A rear view mirror according to claim 1, having at least one
additional antenna formed as self-supporting rigid member located
within the mirror case.
13. A rear view mirror according to claim 1, having an antenna for
a mobile telephone.
14. A rear view mirror according to claim 1, having an antenna for
FM radio reception
15. A rear view mirror according to claim 1, having an antenna for
receiving GPS signals.
16. A rear view mirror according to claim 1, having an antenna for
a remote operation of the car door locks.
17. A rear view mirror according to claim 1, having an antenna for
a for an automatic road toll accounting system.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. Ser. No.
09/404,101 filed Sep. 23, 1999.
FIELD
[0002] This invention relates to an exterior rear view mirror for a
motor vehicle comprising a case containing a mirror glass or other
reflective member and an antenna for transmitting and/or receiving
radio frequency electromagnetic radiation comprising an
electrically conductive layer on a surface of the case.
RELATED ART
[0003] An exterior mirror of this type is disclosed in
GB-A-1590824. The case comprises a body moulded from plastics
material having a bright copper layer deposited on substantially
the whole of its outer surface for receiving a chromium-plated
outer layer. The bright copper layer also serves as an antenna.
SUMMARY OF THE INVENTION
[0004] According to the invention, in a rear-view mirror assembly
of the type described above, the antenna comprises an electrically
conductive layer on a surface of a rigid member forming part of the
mirror assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a perspective view of a vehicle exterior mirror in
accordance with the invention;
[0006] FIG. 2 is a perspective view of the case of the mirror shown
in FIG. 1;
[0007] FIG. 3 is a perspective view of the mirror case shown in
FIG. 2, from a different angle;
[0008] FIG. 4 is a view into the mirror case of FIGS. 2 and 3
through the opening in which the mirror glass would be mounted;
[0009] FIG. 5 is a cross-sectional view taken on the line 5-5 in
FIG. 4;
[0010] FIG. 6 is a cross-sectional view taken on the line 6-6 in
FIG. 4; and
[0011] FIG. 7 is a diagram illustration dimensions of a theoretical
conical antenna.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0012] FIG. 1 shows a vehicle rear-view mirror comprising a
reflective member 10 fitted in a case 11, which is mounted on a
bracket 12, which is secured to one of the front doors 14 of a
motor car 16. As can be seen from FIG. 2, the case 11 has a clip 18
and guides 20 and 22 by means of which it is secured to an internal
frame member (not shown) of the mirror assembly. In accordance with
the invention, a first metallic foil element 30 is secured by
adhesive to the inside surface of the outboard end of the case 11.
As can best be seen from FIG. 4, the element 30 is formed in two
symmetrical halves 30a and 30b interconnected by a link part 32
which is connected by a coaxial cable 34 to a mobile telephone (not
shown). The two symmetrical halves 30a and 30b approximate to a
conical antenna. FIG. 7 shows a cone of half cone angle .theta. and
length .left brkt-bot.. Theoretically .left brkt-bot. should be
equal to wavelength .lambda. of the radio signals (i.e. the speed
of light divided by the centre frequency). In practice, acceptable
results are achieved if .left brkt-bot. is three tenths of the
theoretical value.
[0013] The theoretical formula for the feed-point impedance (Zk) of
a conical antenna is:
Zk=(Zo/.pi.)Ln cot g(.theta./2)
[0014] where Zo is the free space impedance (377 ohms in air) and
"Ln cot g" means "logarithmic cotangent". 30.degree. is a realistic
practical value for .theta..
[0015] The relationship between the angle .theta. and the impedance
of the antenna is linear. Good reception can be obtained if the
actual feed-point impedance is between half and twice its optimum
value. Provided this condition is met, it can be shown from FIGS.
8-15 on page 355 of John D. Kraus, "Antennas", published by McGraw
Hill, ISBN 0-07-0354-22-7, that, because the curve is practically
linear in the area used, a practical optimised value Zo for the
actual feed-point impedance is:
Zo=1500(.left brkt-bot./.lambda.)-113-3
[0016] It follows that the length .left brkt-bot. of the foil
elements 30a and 30b and the half-cone angle .theta. is:
(Zo/.pi.)Ln Cot g.theta./2=1500(.left brkt-bot./.lambda.)-113-3
[0017] In practice, the length .left brkt-bot. of foil element may
be about three tenths of the wavelength .lambda..
[0018] Two other foil elements 36 and 38 that are a mirror image of
one another are secured by adhesive to the central and inboard
parts of the interior surface of the case 11. These foil elements
36 and 38 are connected by a cable 40 to a radio broadcast
receiver, for example an FM radio receiver (not shown).
[0019] In addition to the above two antennae, a third antenna 42 is
connected by a cable 44 to a transponder (not shown) for an
automatic road toll charging system; a fourth antenna 46 is
connected by a cable 48 to a controller for the central door
locking system for the car 16. Another antenna 50, positioned in
the centre of the mirror case 11 is connected by a cable 52 to a
digital radio receiver (not shown) while a further antenna 54 is
connected by a cable 56 to a GPS receiver (also not shown).
[0020] The antennae 42, 46, 50 and 54 are rigid antennae mounted
within the case 11. Although the various cables 34, 40, 44, 48, 52
and 56 are shown as parallel to one another, in practice they are
gathered together so as to extend through the interior of the
bracket 12 into the interior of the car 16, where they are
connected to their respective transmitters and/or receivers.
[0021] Antennae comprising metal inserts moulded into the case 11
may replace the foil antennae 30, 36 and 38. Another alternative is
for the case or cover member to be formed as co-moulding of two
different plastics material, only one of which will accept surface
metallisation. A layer of metal is then deposited on this part to
serve as the antennae.
[0022] If the case has a separate decorative exterior cover member
of the type described in European Patent Application No.
98302674.1, the electrically conductive layer may be formed either
on the inner surface of such cover member or on that part of the
outer surface of the mirror case which is enclosed by the cover
member.
[0023] Alternatively or additionally one or more antennae may take
the form of a conductive layer on part of the mounting for the
mirror glass or other reflective member.
[0024] The mirror assembly may in addition incorporate other
antennae for receiving GPS signals, remote operation of the car
door locks and transponders for automatic road toll accounting
systems. Some of these additional antennae may be formed as
self-supporting rigid members.
* * * * *