More particularly, the invention provides a dual purpose antenna which receives, and can also transmit RF signals, and also converts solar radiation into electric power for battery charging.

The majority of portable radios today are powered by disposable dry batteries, for example the alkaline type, LeClanche type or heavy-duty zinc-chloride cells. These batteries can not be recharged and are disposed of after use-and may then be a cause of environmental pollution. The advantages of using rechargeable batteries, such as for example the nickel cadmium type, would be realized to a greater extent if some convenient method of recharging were available to those not having an electric power source available.

Mobile radio telephones (henceforth: MRT), particularly cellular telephones have come into widespread use at a rate which has rarely been equaled by any new product. Clearly the MRT has met a real and hitherto unrealized requirement.

As is known, the MRT is powered by a storage battery attached to the rear face of its housing. There are two types of battery for this purpose: the multi-use rechargeable battery, which can be for example of the zinc-air or NiMh type, and the disposable non-rechargeable battery, for example those having lithium anodes.

The present invention is concerned only with devices powered by the former type.

Due to the preference of users, particularly female users, there is sharp competition between manufacturers as to making the smallest and lightest MRT possible. The battery, which is responsible for a substantial portion of the weight of an MRT has thus been made as small as possible, retaining just enough

capacity to meet minimum user expectations. Users thus need to carry also a reserve battery, and those that do not may find themselves with an inoperative MRT due to battery exhaustion. Batteries need to be recharged by use of a charger connected to a power source, such as line voltage or a vehicle battery.

There have already been several reports of people in distress whose lives have been saved after calling for help using an MRT. However those lost at sea, in a desert, a war zone or in an uninhabited area are unlikely to have available means to recharge an exhausted battery, making the MRT useless.

Power systems are known combining photo-voltaic solar cells with a rechargeable storage battery, and in some applications even without a storage battery. Applications include operation of lights, street signs, an illuminated house sign (see US Patent No. 5729924 to Reading), spacecraft, line telephones, television sets, radios, watches, radio repeater towers, meteorological data collection stations, and calculators. Such systems are of course of most value in areas where line supply is not readily available.

Devices powered by batteries rechargeable by solar energy hold much attraction for users, who enjoy the thought of getting something for free, and are prepared to spend money on solar devices for such purpose.

An ornamental design for solar battery for mobile telephones has been disclosed by Chiang in USD 382,535. As no technical details are published, it is not certain how this device functions.

In US Patent No. 5,898,932 Zuro et al. propose a MRT provided on its rear face with a solar panel which is to be used for recharging one or two batteries supplying the necessary power. The solar panel has a surface area of at least 15 square inches and covers substantially the whole of the rear face. Such an area corresponds to a rectangle 2 x 7.5 inches, which is the size of the hand-held transceiver of the Panasonic model KX-TC180-W. Present-day MRTs are about half this size, and a solar panel of the size described by Zuro et al. could not be supported by a modern cellular phone.

A further difficulty with the Zuro proposal is that the rear face of a present-day MRT is utilized for attachment and support of the battery. Clearly, if the rear face is to be used as a solar panel, the design of present MRTs, and the batteries supplying power therefor, would need drastic change, as the battery would have to be inserted inside the phone body into some type of slot or recess.

The phone body would need to be made larger, and new means of battery insertion, connection and removal would be needed. Much commercial resistance to such changes would have to be overcome.

OBJECTS OF THE INVENTION It is therefore one of the objects of the present invention to obviate the disadvantages of prior art battery recharging means and to provide an antenna which is usable for battery recharging of any mobile radio receiver device, the antenna serving also for its conventional purpose.

Another object of the present invention is to provide means for solar recharging of batteries as used at present in MRTs and avoiding the need for redesign of batteries in widespread use.

It is a further object of the present invention to provide a dual-purpose antenna which can be adapted for use on MRTs of the form and reduced size in use at present.

Yet a further object is to provide a MRT using a dual-purpose antenna, the battery of the MRT being recharged by exposure of the antenna to the sun.

SUMMARY OF THE INVENTION The present invention achieves the above objects by providing a dual-purpose antenna for a mobile, battery-powered radio-frequency receiver device, said antenna having at least one outer face covered by an array of photo-voltaic cells connectable to a circuit for recharging a battery powering the device, and having a metallic component for at least receiving radio-frequency signals, the metallic component being connectable to the radio receiver of said device.

In a preferred embodiment of the present invention there is provided a dual-purpose antenna hinged to be foldable over a major face of the receiver device.

In a most preferred embodiment of the present invention there is provided a cellular telephone having a dual-purpose antenna, the metallic component of the antenna being arranged for receiving and transmitting radio signals in the range 820-900 megahertz.

Yet further embodiments of the invention will be described hereinafter.

It will thus be realized that the novel device of the present invention serves to make possible a solar rechargeable MRT without requiring drastic design revision of existing MRTs. With only minor adaptations the dual-purpose antenna of the present invention could even be retrofitted on existing MRTs. It is however foreseen that the dual-purpose antenna will become a part of original radio devices designed and manufactured to utilize the dual-purpose antenna to best effect.

The largest solar panel on an antenna which could reasonably be used to recharge the battery of an MRT is about 50 square cm, that is about the area of a major face of a present day MRT. An antenna of this size could be folded against a major face when the MRT is not in use. A larger solar panel would need to be foldable over itself. Folding solar panels are known in the art from use in spacecraft. It is however considered likely that users would prefer to recharge batteries at a slower rate rather than face the expense of a larger, complex and fragile folding solar panel.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described further with reference to the accompanying drawings, which represent by example preferred embodiments of the invention. Structural details are shown only as far as necessary for a fundamental understanding thereof. The described examples, together with the drawings, will make apparent to those skilled in the art how further forms of the invention may be realized.

In the Drawings: FIG. 1 is a perspective view of a preferred embodiment of the dual-purpose antenna according to the invention, shown mounted on a pocket radio, the batteries of which are drawn externally; FIG. 2a is a perspective view of a dual-purpose antenna in cylindrical form ; FIG. 2b is a perspective view of a dual-purpose antenna in the form of a hexagonal prism; FIG. 2c is an elevational view of a dual-purpose antenna in circular form FIG. 2d is an elevational view of a dual-purpose antenna in the form of a trapezoid.

FIG. 3 is a perspective view of a dual-purpose antenna mounted on a ball joint ; FIG. 4 is a perspective view of a rectangular, rounded dual-purpose antenna which can be folded against the rear face of the radio device which it serves; and FIG. 5 is a perspective view of a MRT fitted with a dual-purpose antenna according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT There is seen in FIG. 1 a dual-purpose antenna 10 for a mobile, battery-powered radio-frequency receiver device. The antenna 10 in the present embodiment is shown connected to a pocket radio receiver 12. The battery 14 powering the radio 12, two cells 16 of which are shown externally for illustrative purposes, is in the present embodiment of the rechargeable NiCd type.

While the antenna 10 comprises a single mechanical structure for purposes of assembly to radio 12, electrically the antenna comprises two independent circuits.

The outer face of the antenna is covered by an array of photo-voltaic cells 18. In the present preferred embodiment the outer face is a planar area extending over about 50 square centimeters.

The first electric circuit includes connecting conductors 20 of the array and a one-way section 22 for recharging the battery 14. The one-way section 22, can substantially be integrated into the antenna 10, and ensures that the battery 14 does not discharge through the cells 18.

A metallic component 24 which is a part of the support structure for the cell array 18 forms part of the second circuit and serves the conventional purpose of the antenna for receiving radio-frequency signals. The metallic component 24 is shown connected to the radio 12.

With reference to the rest of the figures, similar reference numerals have been used to identify similar parts.

Referring now to FIG. 2a, there is seen a dual-purpose antenna 26 wherein the outer face extends over an area shaped substantially like a cylinder. Thus when solar radiation strikes the antenna from any direction, some of the solar cells 28 are exposed thereto however the antenna is oriented. Such arrangement is advantageous when the radio device 30 being served by antenna 26 is being carried by foot or on a vehicle.

In this and further embodiments where only a small area of cells 28 is exposed to sunlight the cells used are preferably of a high (at least 15%) efficiency type.

FIG. 2b shows an antenna 32 where the solar cell array 34 is in the form of a hexagonal prism. Such form provides flat surfaces for seating of the solar cells, and so may be easier to manufacture.

The antennas seen in FIG. 2c, a circular disk 36, and FIG. 2d, a trapezoid 38 illustrate further possible forms which may be desirable for improving the styling of a radio device.

FIG. 3 illustrates a dual-purpose antenna 40 mechanically supported on a ball-joint 42. The ball joint 42 is shown connected to a radio device 44. The ball joint 42 is hollow to allow passage for electric wires 46 to connect the antenna to the radio device 44. Such connection allows the user to swivel the antenna 40, so that the array of photo-voltaic cells 48 face in any desired direction within the range allowed by the joint 42. Thus the solar cell array 48 is arranged to face the sun while the radio device 44 could be in any position, for example resting on a horizontal surface, or pressed against the ear of a listener.

Seen in FIG. 4 is a dual-purpose antenna 50, which in the present embodiment is provided with a rectangular array of solar cells 52. The corners 54 of the array are rounded.

The antenna 50 is supported on a hinge 56 which makes possible folding thereof against a major face 58 of the radio receiver device 60, allowing compact and protected transport thereof.

Referring now to FIG. 5, there is depicted a dual-purpose antenna 62, wherein the device swerved thereby comprises a MRT 64. The metallic component 66 is arranged to receive and to transmit RF signals, and is optimized for receiving and transmitting radio signals in the range 820-900 megahertz. The battery 68 shown in the present embodiment is of the NiMh type.

The solar cell array shown 70 can be swiveled around the axis of the metallic component 66 to any desired orientation to facilitate absorption of solar radiation.

The antenna 62 can be arranged to fold in the manner described with reference to FIG. 4.

The scope of the described invention is intended to include all embodiments coming within the meaning of the following claims. The foregoing examples illustrate useful forms of the invention, but are not to be considered as limiting its scope, as those skilled in the art will readily be aware that additional variants and modifications of the invention can be formulated without departing from the meaning of the following claims.