The invention relates to a method of con- trolling a parking fee device disposed in a vehicle, a parking fee device and a device for controlling it.

Today such parking systems are being developed where a conventional automatic parking fee machine found in the street or at the gate of a car park can be replaced by a device disposed in a vehicle, parking time being bought in advance and loaded into the device. The systems are generally based on processor or smart cards

*• having a processor or a memory of their own, paid parking time being recurrently loadable into the card at a point of distribution of parking time, e.g. at a service station, by paying the necessary fee in advance. Thereafter parking time is loaded from the card into a parking fee device disposed in a vehicle by transferring the desired parking time from the processor card to the parking fee device by means of the function keys of the parking fee device. The display of the parking fee device disposed e.g. on the facia panel of a vehicle shows the time loaded thereinto e.g. to a passing traffic warden. It is important in a parking system that the reading on the parking fee device of a vehicle is reliable. The problem with the already existing parking systems based on a parking fee device disposed in a vehicle and with similar parking systems that are being developed is their reliability, since it is rather easy to disassemble and manipulate the devices or to distort the data on the display in different ways so that the traffic wardens have difficulty in carrying out their duties.

The object of the invention is to provide such a method of controlling a parking fee device in which the above disadvantages are eliminated. It is character¬ istic of the method according to the invention that the operation of a parking fee device loaded with parking time and showing the parking time loaded is controlled by transmitting a control command from a separate con¬ trol device to the parking fee device by wireless data transmission and by receiving control data from the transmitting means of the parking fee device by wireless data transmission.

This renders a parking system based on a parking fee device disposed in a vehicle as reliable as the existing conventional systems are. In addition, the control method is very quick and easy and can be carried out by a traffic warden almost simultaneously as he checks the allowed parking duration shown by the parking fee device.

The parking fee device according to the inven- tion, into which a desired amount of parking time can be loaded from a processor card or the like and which shows the parking time still unused, is characterised in that the parking fee device comprises a means for receiving the control command transmitted by wireless data transmission and a means for transmitting control data.

The device of the invention for controlling a parking fee device disposed in a vehicle is charac¬ terised in that the control device comprises means for receiving and transmitting a control command by wireless data transmission with the parking fee device.

The other advantageous embodiments of the invention are characterised by what is disclosed below in. the attached claims.

In the following the invention is described by way of example with reference to the attached drawings, wherein

Fig. 1 shows a general view of a parking fee system based on a parking fee device disposed in a vehicle,

Fig. 2 shows a parking fee device of the inven¬ tion, including a processor card, disposed in a vehicle, Fig. 3 depicts the use of a parking fee device according to the invention and a device for controlling it.

Fig. 1 shows a general view of a parking fee system based on a parking fee device disposed in a vehicle. The system comprises production A of payment units, wherein payment units to be sold are produced onto a distribution card 2 by an apparatus 1. In the production step is also needed a so called authorization card 3, the holder of the card being e.g. the maintainer of the system. In step B payment units are sold to individual drivers by transferring payment units from the distribu¬ tion card 2 to a processor card 4 of the driver. The transfer is made by a distribution device 5 at a spe¬ cified place, such as a service station. In step C parking time is loaded from the pro¬ cessor card 4 to a parking fee device 6 of a vehicle. The processor card 4 is inserted into the device 6 and the desired time together with other possible data are keyed into the memory of the device by means of the function keys thereof.

Fig. 2 shows a more detailed view of the parking fee device, including a processor card, disposed in a vehicle. The parking fee device 6 comprises a dis¬ play 7, function keys 8, a reader of the processor card 4 (not shown) and, naturally, electronic arrangements

known per se controlling-all of these. In addition, the device according to the invention comprises a receiving/ transmitting component 9 for bidirectional communication with the control device, the component advantageously consisting of an infrared link.

The display of a parking fee device may show not only the parking time and/or fee still unused but also the parking zone if the fee varies with the zone,, the system or region identifier if the device can be used in more than one region, and a control display which is needed in connection with the controlling of the device and which shows the traffic warden that the device is in order, belongs to the correct system and has not been manipulated in any way to show incorrect information on the display.

The parking fee device is switched on by pressing the key 'zone', whereby the display shows the amount of money left unused in the device the previous time and instructs the user to insert a processor card. When the processor card is inserted into the device (Fig. 2), the display shows the combined amount of money unused in the card and the device. The parking zone is then entered by pressing the key 'zone' until the number of the zone desired is shown on the display 7. There- after the parking duration desired is selected with an accuracy of e.g. 15 or 30 minutes by the keys 'p-time' . When the key 'start' is pressed, the parking time starts to run and the display instructs the user to remove the processor card 4 from the device 6. Finally, when the vehicle is ready to leave, the device is switched off by pressing the key 'stop' .

The transmitting/receiving component 9 advant¬ ageously comprises optoelectronic components of an infrared link, an ultrasonic transmitter and ultrasonic detectors, or some other transmitting/receiving com-

ponent of the system capable of bidirectional wireless data transmission. For example, the advantages of the infrared link formed by IR diodes are that it is inex¬ pensive and reliable and that the lobe of the pilot beam is easily controllable.

Fig. 3 shows a parking fee device according to the invention and a device for controlling it, the parking fee device being placed on top of the facia panel of a vehicle in such a way that the display can be read from the outside. In the figure a traffic warden is controlling the parking fee device 6 by means of a control device 10. The control device 10 is capable of communicating with the parking fee device 6 from a distance of e.g. 30 to 100 cm through the windscreen of the vehicle. The parking fee device transmits to the control device 10 the information concerning e.g. the parking zone and the parking time originally selected and still unused. The control device 10 may be provided with a similar infrared link as the parking fee device. The data communications protocol is encrypted by a known encryption algorithm of digital data transmission, e.g. in the same manner as in digital mobile phone systems. Thereby only a parking fee device belonging to the sys¬ tem is capable of reading the control command and/or only the data transmitted by such a device can be decrypted by a control device.

It is obvious to one skilled in the art that the different embodiments of the invention are not- limited to the above but may vary within the scope of the attached claims.