WHEEL DISPLAY SYSTEM

Abstract: A taxi has four radially extending arrays of LEDs (38A to 38D) mounted one on each hub cap. A local receiver (32A to 32D) in each hub cap receives data representing a desired image from a local transmitter (24) and stores it in a local memory (34A to 34D). A local control unit (36A to 36D) in each hub cap selectively energises the LEDs in the associated array (38A to 38D) in the required sequence (as the hub cap rotates) to produce an apparent image corresponding to the desired image. A central control station (2) supplies data representing the desired image to a receiver (14) in the taxi. This data is only stored in an associated store (20) when a gate (18) responds to a code in the transmitted data corresponding to that particular taxi. The stored data is then downloaded from the memory by the local transmitter (24).

Description: WHEEL DISPLAY SYSTEM The present invention relates to a wheel display system for creating a visual display on one or more rotating wheels. PCT Publication No WO 98/59333 discloses a bicycle wheel carrying an elongate array of light emitting diodes (LEDs) which are selectively energised as the wheel rotates to generate an apparently stationary image due to the phenomena known as persistence on the retina. The energisation of the array is carried out by a control unit mounted on the wheel in accordance with a program stored in the memory within the control unit. The stored program determines the sequence in which the different LEDs of the array are to be energised. By selecting the timing and energisation of the different LEDs in accordance with the predetermined program, the observer will see an apparently stationary image on the wheel notwithstanding that it is rotating. The effect is achieved because with light flashes of very short duration, the reaction of the human eye to the flash persists long after the flash has finished. Thus, where a series of very short flashes occur over a short time span, less than 0.015 seconds, all the flashes appear to the eye to have occurred at the same time and when the flashes are spaced from one another on the retina, because the array has moved relative to the retina, the eye perceives a composite light pattern which will persist for a short while immediately following the time span. It will thus be appreciated that a program can be created and stored in the memory which will produce almost any desired image for the observer. The image may take the form of alphanumeric information or may take the form of an advertising poster. This system has a number of limitations, namely to change the display the cycle must be halted and the control reloaded with a new program. Also, if both front and rear wheels are required to display images, there is no synchronisation between them. It is an object of the present invention to provide an improved display system for one or more wheels. According to the present invention there is provided a wheel display system for producing an image display on one or more rotating wheels comprising transmission means at a central location and receiver means at a location associated with said wheels, said transmission means being arranged to transmit data representative of a desired image to the receiver means, local transmission means for transmitting data representative of said desired image to a local receiver arranged to be mounted on the or each said wheel, a radially extending array of light emitting devices arranged to be mounted on the or each wheel and control means for the or each wheel responsive to the data received by the local receiver to energise the light emitting devices in a sequence which as the wheel rotates results in an apparent image corresponding to said desired image. A wheel display system, embodying the present invention, will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a block diagram of the system; Figure 2 is a rear view of a vehicle hub cap incorporating parts of the system; and Figure 3 is a section through the hub cap of Figure 2. The system to be described is arranged to provide a visual display on all four wheels of a taxi for advertising or other purposes with the image display being transmitted from a remote central control station. In this way, messages or advertisements can be changed almost instantaneously at will. While the system is designed, in particular, for taxis, it will be appreciated that it can be applied to the wheels of other commercial vehicles, racing cars and even private vehicles. The system shown in Figure 1 includes a central station 2 having a memory 4 for storing data representing different images, a transmitter 6 with an associated transmitting antenna 8 and a control unit 10 having an input such as a keyboard which can select any desired image from the memory 4 and transmit it via the transmitter 6 and antenna 8 to one or more receiving stations 12. Each taxi has it own receiving station (only one receiving station being shown in Figure 1). The receiving station has a receiver 12 and an associated receiving antenna 14. The output of the receiver 14 is fed to a decoder 18 and through a gate 16 to a memory 20. The output of the decoder is connected to open and close the gate 16 in response to receipt of open and close codes unique to that receiving station. A control unit 22, when enabled, for example, in response to the taxi ignition being switched ON, downloads the data stored in the memory and causes the data to be transmitted to an auxiliary transmitter 24 for transmission to four auxiliary receiving units 30A to 30D located one in each hub cap of the taxi. The four receiving units are similar and so only one will be described. The receiving unit 30A has an auxiliary receiver 32A with an associated auxiliary antenna 42A. The output of the receiver 32A is downloaded into a memory 34A. A control unit 36A, when triggered by closure of a reed relay switch 44 A, accesses the memory unit 34 A in response thereto, energises selected ones of a new 38 A of light emitting diodes in a sequence determined by the data stored in the memory. The rate at which the diodes are energised is determined by an oscillator (not shown) which has a frequency that varies with the rate at which the reed switch is closed. A generator 40 mounted at the centre of the hub cap generates an AC signal which is full wave rectified and used to charge a rechargeable battery 42A. The rechargeable battery supplies power to the receiver 32A, the memory 34A, the control unit 36A and the reed relay 44 A. As shown in Figure 2, mounted on the inside of the hub cap 52 are the generator 40A at the centre, the array 38A of LEDs aligned with a radial slit 54 in the hub cap so that while they can be viewed from outside of the hub cap, they lie recessed within the hub cap so as to avoid being struck by foreign objects, the receiving unit 30 A and the reed relay 44A positioned at a location close to the outer perimeter. A magnet 50 for triggering the relay 44 A to close, each time the relay 44 A passes, is secured to the body of the taxi for example the wheel arch. The generator 40A, as can be more clearly seen in Figure 3, comprises a stator 60 which is secured to the centre of the hub cap 54 by adhesive or mechanical fastenings (not shown) to lie coaxial therewith, and a rotor 62. The rotor 62 carries a relatively heavy inertia disc 64. In operation, because taxis are continually accelerating and decelerating, there will be a resistance to delays in the rotor speed relative to the stator speed because of the inertial load on the rotor. This results in relative rotation between rotor and stator and will produce an alternating output voltage as with any generator of this type. The output voltage is full wave rectified and limited (eg with a zenor diode) and used to maintain the rechargeable battery 42A charged. In operation, when the control centre wishes to cause a taxi to generate a particular display on its hub caps, it will transmit data taken from the memory 4 and representative of that display together with a unique opening and closing code related to the taxi in question. While all the taxis in the relevant area will receive the transmitted data, only the taxi with the relevant diode 18 will respond and allow the transmitted data to pass through the gate 16 into the memory 20. The local control unit 22 in the taxi takes the data from the memory 20 and transmits it to the four local receivers 30A to 30D for storage in respective memories 34A to 34D. The control units 36A to 36D respond to the stored data to trigger the LED arrays 38A to 38D in the appropriate sequences to reproduce the desired image on each of the four hub caps. The operation of the reed relays 44 A to 44D ensure the correct positioning of the images on the hub caps and, by measuring the repetition rate of the relays, any stretching or contracting of the image with changes in speed of the hub caps can be countered. It will be appreciated that while the local control unit 22 transmits the same image data to each wheel simultaneously, the auxiliary receivers can be provided with a code activated gate similar to the gate 16 so that they receive the same image at different times or receive different images at the same time. While both the control and local transmitters are radio transmitters and receivers using cellular telephone or small packet switch techniques, it will be appreciated that in the case of the local transmitters and receivers, ultra sonic, inductive or infrared communication systems can be used instead. Also, while all the display data is stored at the central control station, each local station can store all the data instead with the central station providing command signals to release from the local memories the desired image data when required. Instead of the generator taking the form of a stator and rotor, it can be replaced by light cells or any other form of electrical generator. While the image displayed on each wheel can be an apparently stationary one, it can also take the form of a moving image if the display data stored in the memory is changed every cycle or every few cycles. In a modification, instead of the reed relay providing the trigger signal, it might be possible to derive the trigger signal from the generator when the generator output includes a component representative of a particular angular position.

Claims: CLAIMS 1. A wheel display system for producing an image display on one or more rotating wheels comprising transmission means at a central location and receiver means at a location associated with said wheels, said transmission means being arranged to transmit data representative of a desired image to the receiver means, local transmission means for transmitting data representative of said desired image to a local receiver arranged to be mounted on the or each said wheel, a radially extending array of light emitting devices arranged to be mounted on the or each wheel and control means for the or each wheel responsive to the data received by the local receiver to energise the light emitting devices in a sequence which, as the wheel rotates, results in an apparent image corresponding to said desired image. 2. A system according to Claim 1, wherein each local receiver and associated local control means and array of light emitting devices are mounted on a wheel hub cap. 3. A system according to Claim 2, wherein the light emitting devices are mounted in the inside of the hub cap to face a radially extending slot in the hub cap through which the array can be viewed. 4. A system according to Claim 2 or to Claim 3, wherein the local receiver, associated local control means and array of light emitting devices are powered by rechargeable battery means mounted on the hub cap. 5. A system according to Claim 4, including generating means mounted on the hub cap for keeping the rechargeable battery charged. 6. A system according to Claim 5, wherein the generating means comprises light cell means. 7. A system according to Claim 5, wherein the generating means comprises a stator rigid with said hub cap and extending coaxially therewith and a rotor carrying an inertial load to produce relative rotation between the stator and rotor as the hub cap accelerates and decelerates. 8. A system according to any one of Claims 3 to 7, including trigger means mounted on the hub cap to be triggered each time the trigger means passes a particular angular position, the trigger means acting to cause the image initiated by the local control means to be initiated in the same angular position on each rotation of the hub cap. 9. A system according to Claim 8, wherein the trigger means comprises a reed relay which is triggered by a magnet located adjacent said particular angular position. 10. A system according to any preceding claim, wherein said local transmission means communicates with said local receivers by radio frequency transmissions. 11. A system according to any preceding claim, including a memory for storing data received by said receiver means and a gate for inhibiting storage of data in said memory from said receiver means until opened in response to a code received by said receiver means. 12. A system according to any preceding claim, including storage means associated with each local receiver for storing the data recorded by said local receiver. 13. A system according to any preceding claim, wherein the receiver means is mounted in a taxi and there are four local receivers associated with the receiver means one for each wheel of the taxi whereby all four wheels of the taxi can display a desired image as the wheels rotate.

Inventors: MARGETSON GUY EDWARD JOHN, WYATT ROY, MARGETSON, GUY, EDWARD, JOHN, WYATT, ROY
Applicants: ADFLASH LIMITED, MARGETSON GUY EDWARD JOHN, WYATT ROY, MARGETSON, GUY, EDWARD, JOHN, WYATT, ROY
Application year: 2000
Main classification: G09F21
IPC codes: G09F9, G09F21, G09G3