WO1991000626A1

WO1991000626A1 - Rear view mirrors including radio aerials

Info

Publication number: WO1991000626A1
Application number: PCT/GB1990/000991
Authority: WO
Inventors: William Sydney Charlton
Original assignee: Crowe, Brian, John
Priority date: 1989-06-27
Filing date: 1990-06-27
Publication date: 1991-01-10
Also published as: GB8914700D0

Abstract

A rear view mirror for a motor vehicle. The mirror has a hollow casing (2) and a mirror element with a reflective surface (16). The reflective surface is in the form of a metallised layer, which acts as an aerial element. An amplifier (18) is also provided within the housing.

Description

REAJ VIEW MIRRORS INCLUDING RADIO AERIALS

This invention relates to motor vehicle rear view mirrors including radio aerials.

According to a first aspect of the present invention, there is provided a rear view mirror for a motor vehicle, the mirror comprising: a hollow casing, one wall of which is constituted by a mirror element having a reflective surface; an aerial element, located within the casing; amplifier means, for amplifying signals received by the aerial element; power supply means for feeding power from said vehicle power source to said amplifier means; and means for passing electrical signals, output from the amplifier means, to radio receiving apparatus of said vehicle.

Preferably, the reflective surface is formed by a metallised layer on an internal surface of the mirror element, which layer also constitues said aerial element. Alternatively, however, there may be provided a separate aerial element, in the form for example of a ferrite rod.

The amplifier should be positioned close to the aerial element and in the preferred embodiment, the amplifier means is located within the hollow casing and power supply means are provided to feed current from the vehicle power system to said amplifier means.

The amplifier means may be a wideband amplifier to amplify signals over the complete desired range of RF frequencies, or may comprise several individual RF amplifiers, one for each RF frequency band (LW, MW SW & VHF), and may contain either a single stage of amplification or several stages to produce the necessary S/N ratio for the RF signals fed to the radio tuner unit.

For a better understanding of the present invention, and to show how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:-

Fig. 1 shows a rear view mirror,, viewed from outside in the direction towards its reflective surface; and

Fig. 2 is a sectional view taken on the line II-II of Fig. 1.

The mirror shown in Figs. 1 and 2 comprises a casing made up from a generally rectangular recessed body 2 and a mirror element 4 which seats on an internal ledge 6 of the body 2, where it is retained by a bezel 8. The body 2 and the bezel 8 are moulded from plastics material, such as nylon or acrylonitrile butadiene styrene, and are secured together by ultra¬ sonic welding. The mirror element 4 is, for example, moulded from polycarbonate which is silvered on the surface facing inwardly of the casing in order to make it reflective. Alternatively, the mirror element could be made of glass. Where the mirror element 4 is made from polycarbonate or some other plastics material, it may be ultrasonically welded to the bezel 8 and/or the body 2.

In the illustrated embodiment of the invention, as shown in Fig. 2, the mirror element 4 comprises two portions 10 and 12 which are inclined to each other by an angle which, in the illustrated embodiment, is 7°. The two portions 10 and 12 are planar, and are integral with each other. At the junction between the two portions 10 and 12 the bezel 8 has a separating element 14, so that the portions 10 and 12 are framed separately from each other by the bezel 8. Incidentally, it should be noted that rear view mirrors according to the present invention need not have two portions as illustrated, and may be formed, entirely conventionally, with a single reflecting surface. On the internal face of the mirror element 4, there is a metallised layer 16, which serves as an aerial element. The metallised layer may be applied to the inernal surface of the mirror element under a vacuum. The formation of the aerial element as a metallised layer in.this manner allows the rear view mirror to be manufactured simply, without requiring the use of special materials for the body 2 or major changes in the method of manufacture of the mirror. The aerial element may be used either for receiving or transmitting radio signals, thus enabling it to be used either in conjuction with a car radio or, for example, with radio telephone apparatus.

The metallised layer 16 is connected by an electrical connection 17 to an integrated circuit amplifier 18. The integrated circuit amplifier 18 is mounted, via a board 20, to the body 2 of the mirror. The amplifier 18 increases the signal levt^" so as to provide the required signal-to-no__.se (S/N) ratio at the input to the radio equipment 15 to which it is connected. Otherwise, the signal could be swamped by noise signals resulting from the proximity of the aerial element to the engine of the motor vehicle to which the mirror is attached, and to electronic circuitry within the motor vehicle. In addition, it is advantageous to locate the integrated circuit amplifier, within the casing, as far as possible from the section of the rear view mirror which is to be connected to the motor vehicle. This further reduces the problems of electrical noise.

In use, the mirror is fitted, as is conventional, to the front wing or door of a car or other vehicle to provide a rearwards view for the driver of the vehicle. The mirror is mounted on the vehicle by means of the hinge portion 22, which engages a co-operating portion fixed to the vehicle. The mirror is positioned such -4- that it gives a field of view extending close to, and perhaps including, the side of the car.

Running from the integrated circuit amplifier 18 to the appropriate electronic apparatμs within the 5 motor vehicle are a pair of power lines 24, and the RF signal output line 26, which must be shielded against external interference.

Thus, the aerial element 16 serves as a replacement for the usual whip aerial, but is less

10 obtrusive and less prone to vandalism. Further, in comparison with known radio aerials located within rear view mirrors, the rear view mirror aerials according to the present invention are simple to manufacture and help to overcome the problems associated with locating

15 radio aerials adjacent electrical and electronic apparatus.

If the motor vehicle is provided with external rear view mirrors on both sides thereof, both mirrors can incorporate metallised layers 16 as aerial

20 elements, and amplifier means, as shown in the Figures, although, of course, the hinge portions 22 will be different, reflecting the fact that the two mirrors are to be fitted to different sides of the vehicle. The presence of two aerial elements 16 is found to improve

25 radio reception. Moreover, combining the provision of aerial elements within rear view mirrors on both sides of the vehicle with aerials on, or in, the front and rear windscreens of the vehicle may result in further improvement in the signal provided to the vehicle's

30 radio equipment.

Further, the mirrors can be provided with heating circuitry for de-misting the mirror element 4, and can also include manual or automatic dipping arrangements. Motor driven or manual adjusting means for the mirror

35 element 4 can also be provided. All or some of such additional features can be accommodated within the casing defined by the body 2 and the mirror element 4.

Although not the preferred arrangement, the aerial element may be provided, separate from the reflective mirror coating, by, for example, a ferrite rod aerial mounted inside the mirror housing. Amplifying means would, however, still be required to provide an adequate signal for feeding to the vehicle's radio equipment.

Claims

1. A rear view mirror for a motor vehicle, the mirror comprising: a hollow casing, one wall of which is constituted by a mirror element having a reflective surface; an aerial element, located within the casing; amplifier means, for amplifying signals received by the aerial element; power supply means for feeding power from said vehicle power source to said amplifier means; and means for passing electrical signals, output from the amplifier means, to radio receiving apparatus of said vehicle.

2. A rear view mirror as claimed in claim 1, wherein said reflective surface comprises a metallised layer on an internal surface of the mirror element, which layer also constitutes said aerial element.

3. A rear view mirror as claimed in any preceding claim, wherein said amplifier means is positioned inside said hollow casing.

4. A rear view mirror as claimed in preceding claim, wherein the amplifier means comprises a broad band RF amplifier, for amplifying signals over the complete range of frequencies for said radio receiving means.

5. A rear view mirror as claimed in any of claims 1 to 3, wherein the amplifier means comprises a plurality of individual RF amplifier circuits, each for amplifying signals within a respective RF frequency band.

6. A rear view mirror substantially as herein described with reference to, and as shown in, the accompanying drawings.

7. A motor vehicle, provided with one or two rear view mirrors as claimed in any one of the preceding claims. 9. A motor vehicle as c"^*^imed in claim 7 comprising further radio aeri 3 located on, or in, front and rear windscreens respectively of the vehicle.