PROGRAMMABLE FUSE AND PROGRAMMING DEVICE FOR TIMER

Abstract: The present invention relates to a programming device and to a programmable fuse for switching off electric current. The fuse comprises means (208) to monitor the strength of the electric current and means (210) to switch off the passage of the electric current through the fuse. To enable versatile timing of electric appliances, the fuse comprises means (218) to store one or more desired time periods, an interface (222) to a separate programming device of the time periods, and means (216, 220) to control the switching means (210) on the basis of the time periods stored.

Description: PROGRAMMABLE FUSE AND PROGRAMMING DEVICE FOR TIMER FIELD OF THE INVENTION The present invention relates to a programmable fuse for switching off electric current, the fuse comprising means to monitor the strength of the electric current and means for switching off the passage of the electric current through the fuse. BACKGROUND OF THE INVENTION Fuses are used in a variety of environments to protect the environment and the users against faults in electric equipment and circuits. In a building, fuses are generally placed in a centred manner in one location in connection with the building's main power switch inside the building. It is previously known to place, in connection with the fuse, some kind of an adjustable timer apparatus, with the aid of which it is possible to restrict the passage of electric current to the circuit behind the fuse as a function of time. The most typical application is socket posts intended for the heating of vehicles, which posts, in addition to the socket, usually also comprise an automatic fuse and a timer, which is used to switch on the circuit at the desired time of day, typically for a few hours. Figure 1 presents an example of the structure of an arrangement based on prior art in connection with a socket post. The arrangement comprises a connection to an electrical network 100, a socket 102 for coupling the vehicle's heater, an adjustable timer 104 which is used to set the desired switched-on time, a switch 106 which is controlled by the timer, and a fuse 108 which can be a conventional disposable fuse or a so-called automatic fuse. The known arrangements have been designed for single applications and their use is limited. In addition, their use requires fixed installations. Further, so far it has not been possible to realise an effortless setting of time-based availability of electric current in electrical networks inside buildings. The timer switches used in industry are similar in structure to the above- mentioned solutions and require fixed installation. There are also applications in which the setting of timer for the control of electric current must be possible only for certain persons. For example, in connection with sockets for cars, this restriction of use is realised using lock- able socket boxes. In buildings, this solution is impractical and requires separate installation. In old premises, this is not even possible owing to lack of space. DESCRIPTION OF THE INVENTION The object of the present invention is thus to realise an arrangement which can be used to effortlessly implement versatile timing in both new and existing buildings. The object of the invention is also to realise an arrangement which can be used to restrict the control of timing to certain persons or groups of persons. This will be achieved with a fuse of the type described in the preamble, which is characterised in that the fuse comprises means to store one or more desired time periods, an interface to a separate programming device for the time periods and means to control the switching means on the basis of the time periods stored. The invention also relates to a programming device for a timer, the device comprising a key pad, a display and an interface to the programmable device. The programming device according to the invention is characterised in that the device comprises means to store codes of different timers, means to store a security code which enables programming, and means to enable the use of the programming device when the stored security code is fed to the device. The solution of the invention has many benefits. A programmable fuse, such as in the invention, can be placed anywhere in place of a conventional fuse, whereby the electrical network inside the building can be controlled on the basis of time. Thus, for example, the lighting of a room can be controlled by leaving the room's light switch in the "on" position and by using the fuse to control the lights. The preferred embodiments of the invention can be seen in the independent claims. DESCRIPTION OF THE DRAWINGS In the following, the invention is explained in more detail by reference to the examples in the enclosed drawings, where Figure 1 presents the above-described example of a solution according to the prior art, Figure 2 illustrates an example of the structure of a fuse according to the invention, and Figure 3 illustrates an example of the structure of a programming device for a timer according to the invention. PREFERRED EMBODIMENTS OF THE INVENTION The present invention relates to a programmable fuse, which comprises a timer, which can be programmed using a separate programming device, and memory for the storage of time periods set. In a preferred embodiment of the invention, a fuse according to the invention can replace a conventional fuse in a fuse box, and the desired time periods can be stored in the fuse, whereupon power is connected to the electrical network behind the fuse. In the following, we shall discuss in more detail the structure of a preferred embodiment of the fuse according to the invention with the help of the example presented in Figure 2. The fuse comprises connection means 200, 202 to the electrical network and fastening means 204, 206 for fastening the fuse to the fuse box. The connection and fastening means can be realised by using prior art technology so that the fuse can be used in existing fuse boxes. The fuse comprises means 208 for monitoring the strength of the electric cur- rent between the fuse connection means 200, 202. The fuse also comprises switching means 210 used to switch off the passage of electric current between the fuse connection means 200, 202. The switching means can be realised using e.g. relays. The means 208 thus monitor the strength of the current, and if the strength of the current exceeds the prescribed threshold, the means 208 control the relay 212 so that the passage of current through the fuse is switched off. This is the normal functioning of the fuse. The fuse additionally comprises a control connection 214, which can be used to switch on the relay again after the electric current has been switched off owing to overcharge. This control connection can be realised either manually, as in the ex- isting automatic fuses, or with the aid of a programming unit described below. The fuse can also attempt automatic reswitching e.g. three times after a minute's pause. The fuse according to the invention additionally comprises a control unit 216, memory means 218, a timer means 220 and an interface 222. The inter- face 222 is used to store one or more desired time periods in the memory means 218 of the fuse, whereby the fuse is desired either to enable or prevent the passage of electric current through the fuse's connection means 200, 202. The control unit 216 together with the timer means 220 read the stored time periods from the memory 218 and control 224 the switching means 210 correspondingly. The switch is thus controlled to be "on" or "off regardless of the strength of the electric current in accordance with the time periods stored in the memory. The fuse can additionally comprise means 226 to show the stored time periods and the status of the fuse at any particular moment with the aid of light-emitting diodes or an LCD, for example. The status of the fuse at that moment can be shown, for example, so that when the fuse is on, a red LED is lit, and when the fuse is off, a green LED is lit. In one alternative embodiment, the fuse does not include a display, but instead, the status of the fuse and the stored time periods can be verified with a separate programming device. In another alternative embodiment, the display means 226 give a warning when the electric current approaches the pre-set threshold value, where the relay goes off. The display means can also show detailed information on power consumption. The control unit 216 controls the function of the other parts of the fuse, such as the display means 226. The control unit 216, the memory means 218 and the timer means 220 can be realised preferably by using a mi- croprocessor or separate components at different levels of integration, as is obvious to one skilled in the art. The memory means 218 can be realised per se according to the prior art. A method according to the invention can in suitable parts preferably be realised through software in the control unit 216. In general, fuse boxes contain several fuses. As will be presented be- low, a fuse according to the invention can be programmed with a separate programming device, for example an infrared or wireless connection. A fuse according to the invention comprises the means 218 for the storage of an individual code, which separates a fuse from another. Thus in remote .control, each fuse can be controlled separately, with the aid of the individual code of each fuse. A fuse reacts to the control only if the individual code of the fuse is sent in connection with the control. The fuse additionally comprises means 228 to take its operating voltage from the mains voltage system. In case of power cuts, the fuse may also comprise a battery 230. On the other hand, the memory means 218 can also be realised with the aid of flash memory, whereupon a power cut will not cause the stored data to be erased and the battery 230 will thus be unnecessary. The fuse's interface to its programming device can be realised in many ways. The interface can be physical, comprising, for example, one or more contact surfaces. During the input of programming data, the programming device is then connected to the fuse with the aid of a cable, for example. The interface can also be realised with the aid of an infrared or wireless connection. In that case, the interface comprises either an infrared or a wireless receiver. The fuse can naturally be realised at different operating voltages and at different current limiting values. Next we shall discuss in more detail the structure of a preferred em- bodiment of the programming device for a timer according to the invention with the aid of the example presented in Figure 3. The programming device comprises a key pad 300 for the input of data in the piece of equipment and a display 302 which displays the data to be programmed. The programming device also comprises an interface 304, with the aid of which the programming device is in contact with the piece of equipment to be programmed. The interface can be used to realise the connection as a fixed connection with the aid of a cable or contact surfaces or as an infrared or radio connection, as was presented above in connection with the fuse. The key pad is used to input in the programming device the desired data which the user wants to transmit to the pro- grammable timer. The device comprises a control unit 306 and memory means 308, where the time periods are stored for transmission. The memory means 308 can additionally be used to store the security code which enables programming. The purpose of this security code is to prevent an unauthorised programming of the timer. The equipment requests the security code on programming, and if the correct code is not provided, the control unit 306 prevents the completion of the programming. The memory means 308 can additionally be used to store codes of different timers, which makes it possible to control different timers with the same programming device. A programming device according to the invention can be used, not only in connection with the programming of the programmable fuse, but also in programming the timers of other remote control equipment, for example the timer of a video cassette recorder. In a preferred embodiment of the invention, the programming device receives its operating voltage through the interface 304. Thus, for example, in using a fixed connection between the fuse and the programming device, the battery 310 of the programming device can be charged in making the first connection. Programming can then be carried out quickly without charging the battery until the battery becomes empty and charging is necessary again. Although the invention has been discussed above with reference to an example as presented in the enclosed drawings, it is evident that the invention is not limited to that particular example alone, but instead, it can be modified in many ways within the scope of the inventive idea presented in the attached claims.

Claims: CLAIMS 1. A programmable fuse for switching off electric current, the fuse comprising means (208) to monitor the strength of the electric current and means (210) for switching off the passage of the electric current through the fuse, characterised in that the fuse comprises means (218) to store one or more desired time periods, an interface (222) to a separate programming device for the time periods, and means (216, 220) to control the switching means (210) on the basis of the time periods stored. 2. A fuse according to claim 1, characterised in that the fuse comprises fastening means (204, 206), with which the fuse is fastened to a fuse box. 3. A fuse according to claim 1, characterised in that the fuse further comprises means (226) to display the time periods stored. 4. A fuse according to claim 1, characterised in that the interface (222) comprises one or several contact surfaces. 5. A fuse according to claim 1, characterised in that the interface (222) comprises an infrared receiver. 6. A fuse according to claim 1, characterised in that the in- terface (222) comprises a radio receiver. 7. A fuse according to claim 1, characterised in that the fuse also comprises means (228) to take operating voltage from the mains voltage. 8. A fuse according to claim 1, c h a ra cte ri s e d in that the memory means (218) are realised with the aid of a semiconductor memory. 9. A fuse according to claim 1, characterised in that the fuse comprises means (218) to store an individual code, which separates a fuse from another. 10. A programming device for a timer, the device comprising a key pad (300), a display (302) and an interface (304) to the device to be programmed, c h a ra c te ri s e d in that the device comprises means (308) to store codes of different timers, means (308) to store a security code which enables programming, and means (306) to enable the use of the programming device when the stored security code is fed to the device. 11. A programming device according to claim 9, characterised in that the programming device receives its operating voltage through the interface (304). 12. A programming device according to claim 9, characterised in that the interface (304) is formed by contact surfaces. 13. A programming device according to claim 9, characterised in that the interface (304) is a wireless connection to the device to be programmed. 14. A programming device according to claim 11, c h a ra cte ri s e d in that the programming device comprises a rechargeable source of voltage (310).

Inventors: NIMMO JAMES, NIMMO, JAMES
Applicants: NIMMO JAMES, NIMMO, JAMES
Application year: 1997
Main classification: H02H3
IPC codes: H02H3