The invention has been developed primarily for domestic and commercial use and for controlling the supply of electrical power to one or more peripheral devices of a computer, and will be described hereafter with reference to that application. However, it will be appreciated that the invention is not limited to this particular field of use and is also suitable for controlling the supply of electrical power to other devices.

The term"power board"refers to a device that is configured for connection to the mains supply and which usually offers a plurality of output connections for a respective plurality of electrical loads. These boards are also commonly referred to as power strips or power bars.

DISCUSSION OF THE PRIOR ART Known domestic power boards include a housing and a lead extending from the housing for connecting to a mains outlet socket. Also typically included is an array of output connectors extending along a face of the housing for selectively mating with complementary connectors of respective electrical loads such as electrical appliances, computer peripheral devices, electrical lights, and the like.

There have been many attempts to control the supply of power to these loads, including, at the less complex end of the spectrum, the use of overload switches and an ON/OFF switch for each socket. At the other end of the spectrum, use has been made of very complex and relatively expensive circuitry that receives logic signals from an external device.

All these devices are either very limited in the amount of control that is offered or, alternatively, are too expensive or complex to be widely acceptable for domestic or general applications.

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

DISCLOSURE OF THE INVENTION It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

According to a first aspect of the invention there is provided a power board for connecting a load to a primary power source, the board including: an input connector for electrically connecting to the power source; an output connector for electrically connecting to the load; a switch being electrically disposed between the input and the output connectors for changing between an open state and a closed state to respectively disconnect and connect the power source and the load; and an actuator to be supplied with a power signal from a remote electric device, wherein the actuator is responsive to the signal ceasing to progress the switch to the open state.

Preferably, the remote device is supplied with power through a like power board.

More preferably, the board includes a plurality of output connectors for electrically connecting to a corresponding plurality of loads.

Preferably also, the switch, in the open state, does not disconnect all the loads from the power source. More preferably, the remote device is supplied with power through one of the output connectors such that the switch, in the open state, does not disconnect the remote device from the power source. In other embodiments, however, the switch, in the open state, disconnects all the loads from the power source.

According to a second aspect of the invention there is provided a power socket for connecting a load to a primary power source, the socket including: an input connector for electrically connecting to the power source; an output connector for electrically connecting to the load; a switch electrically disposed between the input and the output connectors for changing between an open state and a closed state to respectively disconnect and connect the power source and the load; an actuator to be supplied with a power signal from a remote electric device, wherein the actuator is responsive to the signal ceasing to progress the switch to the open state and the remote device is supplied with power through a like power socket.

Preferably, the socket includes a housing for containing the switch and the actuator and for supporting the input and the output connectors. More preferably, the socket includes a plurality of spaced apart output connectors for electrically connecting to respective loads and for allowing these loads to be selectively connected to the primary power source.

Preferably also, the output connectors are arranged in an array. More preferably, the array is linear.

In a preferred form, the remote device includes a port for providing the signal.

More preferably, the remote device is a computer and the port is selected from one of the group comprising: USB; SCSI; and any other port that has a low voltage power supply capability.

Preferably, the remote electric device is selected from the group including: a laptop; a desktop computer; a computer peripheral device; a palm top device; a server; a multimedia device; and any other computing device.

Preferably also, the actuator is responsive to the presence of the signal for progressing the switch to the closed state.

According to a third aspect of the invention there is provided a power board for connecting a primary power source to a load, the board including: a housing ; an input connector mounted to the housing for electrically connecting to the primary power source; an output connector mounted to the housing for electrically connecting to the load; a switch located within the housing and being electrically disposed between the input and the output connectors for changing between an open and closed state to respectively disconnect and connect the power source and the load; and a controller mounted to the housing for receiving a power signal from a remote electrical device and, in the absence of that signal, progressing the switch to a open state.

According to a fourth aspect of the invention there is provided a method for connecting a load to a primary power source, the method including: providing a housing; mounting an input connector to the housing for electrically connecting to the primary power source; mounting an output connector to the housing for electrically connecting to the load; locating a switch within the housing that is electrically disposed between the input and the output connectors for changing between an open and closed state to respectively disconnect and connect the power source and the load; and mounting a controller to the housing for receiving a power signal from a remote electronic device and, in the absence of that signal, progressing the switch to a open state.

According to a fifth aspect of the invention there is provided an electrical device that draws power from a mains supply, the device including:

a housing; a power supply located within the housing; an input connector for connecting to the mains supply; an automated switch being disposed between the input connector and the power supply for moving between an open and a closed state for respectively electrically disconnecting and connecting the connector and the supply, wherein the switch is responsive to a remote control signal for moving to the closed state.

Preferably, the remote control signal is a power signal and is provided via a cable. More preferably, the cable also carries a data signal. Even more preferably, the data signal and the power signal are carried in separate conductors within the cable.

Preferably also, the device is responsive to the data signal. For example, in some embodiments, the device is a printer, the remote control signal is provided by a computer, and the data signal includes the print jobs sent to the printer by the computer. It will be appreciated that the term"computer"also includes a computer network. Preferably, the cable is a USB cable.

In a preferred form, the device is located in a casing that is separate from the housing. More preferably, the housing is within the casing. However, in other embodiments, the housing is outside the casing.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a schematic view of the power board according to the invention that is connected to a plurality of remote electric devices; Figure 2 is a circuit diagram of the power board of Figure 1 ; Figure 3 is a front view of a further power board according to the invention; Figure 4 is a side view of the power board of Figure 3; Figure 5 is a top view of another power board according to the invention; Figure 6 is a top view of an alternative power board according to the invention; Figure 7 is a top view of a further alternative power board according to the invention ; Figure 8 is a top view of another alternative power board according to the invention; Figure 9 is a top view of a further power board according to the invention;

Figure 10 is a top view of a cable for use with the power board according to the invention; Figure 11 is a top view of a cable for use with the power board of Figure according to the invention; Figure 12 is a schematic diagram of the circuitry of the power board of Figures 3 and 4; Figure 13 is a schematic diagram of the circuitry with the power board of Figure 7; Figure 14 is a schematic diagram of another power board according to the invention; Figure 15 is a schematic diagram of an alternate switch for use with the power boards of the invention; and Figure 16 is a schematic view of a further embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and in particular to Figure 1 and Figure 2, there is illustrated a power board 1 for connecting a primary power source in the form of a mains supply (not shown) to a plurality of loads. The loads include a desktop computer 2, a monitor 3 for computer 2, a printer 4, and a table lamp 5. Board 1 includes a moulded plastics prismatic housing 6. An input connector, in the form of a three pin domestic plug 7, includes a neutral pin 8, an earth pin 9 and active pin 10, and is mounted to housing 6 via a flexible insulated lead 11. A plurality of output connectors, in the form of three pin domestic power sockets 12,13 and 14, are mounted to the housing for electrically connecting to printer 4, monitor 3 and lamp 5, respectively. As shown in Figure 2, a switch, in the form of a relay 15, is located within housing 6. This relay is electrically disposed between plug 7 and sockets 12,13 and 14 and includes contacts 16 for changing between an open and closed state to respectively disconnect and connect the power source and monitor 3, printer 4 and lamp 5. A controller, in the form of an energising coil 17 of relay 15, is mounted, albeit indirectly, to housing 6 for receiving a power signal from computer 2 and, in the absence of that signal, progressing contacts 16 to an open state.

Board 1 includes a further socket 18 that operates independently of relay 15 and which is arranged on housing 6 adjacent to socket 14. All of the sockets 12,13, 14 and 18 are of the domestic three-slot variety, and each includes a neutral slot 19, an active slot 20, and an earth slot 21.

Socket 18 selectively complementarily receives a standard domestic electrical plug 22 of a cable 23. The cable terminates at a distal end that is complementarily engaged with the power input socket 24 of computer 2. Likewise, sockets 12,13 and 14, additionally selectively receive complementarily standard domestic electrical plugs 25,26 and 27 of cables 28,29 and 30 respectively. These cables terminate at their distal ends and are complementarily respectively engaged with the power input to printer 4, monitor 3 and lamp 5.

Housing 6 includes a pair of peripherally mounted USB ports 31 and 32. As shown in Figure 1, USB port 31 is coupled with a complementary connector 33 of a USB cable 34. This cable extends to a distal end that terminates in a connector 35 that is complementarily received within a USB port 36 of computer 2. Similarly, USB port 32 is engaged with a complementary USB convector 37 of an RS232 cable 38. This cable extends to a distal end that terminates in a USB connector 39 that is complementarily received by printer 4.

As best illustrated in Figure 2, USB ports 31 and 32 each have four wires 40,41, 42 and 43. Wires 40 and 41 have a potential difference of about 5 Volts maintained between them by computer 2. That is, when computer 2 is operating and cable 34 is engaged with port 36, wires 40 and 41 will provide a supply voltage of about 5 Volts. In this embodiment the current limit of the supply is about 100 mA, which is in accordance with the USB standard. In embodiments where use is made of a different cabling standard, the voltage and current supply capacities are also different.

It will be appreciated by those skilled in the art that the USB specification has two options for supplying current. The first is a low power mode where the supply of power to devices is capped at a maximum current of 100 mA. The second is a high power mode that allows up to 500 mA of current to be drawn. All computers with a USB interface must support the low power mode, although not necessarily the high power mode. In some cases, the attached USB peripheral is able to try and draw more current, sometimes through software negotiation on the bus itself.

In the embodiments of the invention described in this specification, the current drawn is restricted to lie within the 100 mA limit referred to above. This allows 100% compatibility with the USB ports of the relevant computer or other device. As the control functionality of the power board described above is provided by a single relay and a small number of LED's, the 100 mA limit is not problematic. Additionally, the

power board of the above embodiment is a dumb device, with no ability to negotiate power supply capacity.

Wires 40 and 41 are connected across coil 17 of relay 15 such that, when computer 2 is operating, contacts 16 are moved to the closed configuration. If computer 2 is turned off-in that it is no longer operating-the potential difference between wires 40 and 41 will no longer be maintained and coil 17 will be de-energised. Accordingly, the contacts will move to the open configuration.

Wires 42 and 43 connect between USB port 31 and USB port 32. In this embodiment, board 1 is not responsive to the signals carried by wires 42 and 43. In other embodiments, however, board 1 includes additional circuitry and functionality that is controlled by a user of computer 2.

In this embodiment, cables 34 and 38 are daisy chained together so that the relevant data signals, while being passed through board 1, are exchanged between computer 2 and printer 4. In that way, there is no need for computer 2 to have two separate USB ports to control computer 1 and printer 4. In other embodiments where computer 2 does have a further USB port (not shown), or a spare port on a USB hub is not available (not shown), the printer is directly connected to that further port. In some cases, this leaves port 37 unused while, in other cases, port 37 is utilised as a USB interface for another device.

Board 1 includes a power master switch 44 that is mounted to housing 6 and which is electrical connected to pin 10 to allow board 1 to be selectively isolated from the mains supply. Switch 44 is actuated by a user and moves between an open and a closed state. When in the open state, switch 44 effectively renders board 1 inoperable.

That is, it is not possible to connect any of the loads to the mains supply.

A relay override switch 45 is disposed electrically in parallel with contacts 16 for allowing the user to convert board 1 between a controlled configuration and an independent configuration. In the controlled configuration the electrical connection of slots 20 to pin 10 is contingent upon the state of contacts 16 and, hence, the presence or otherwise of the control signal. In the independent configuration, slots 20 are directly electrically connected to pin 10. In both cases this functionality is continent upon switch 44 being in the closed state.

Board 1 also includes a overload protection device 46 that is disposed intermediate switch 44 and the parallel combination of relay 15 and switch 45. In other

embodiments device 46 is disposed in a different location. Device 46 includes a preset current limit at which it isolates sockets 12,13, 14 and 18 from plug 7. That is, there is an upper limit on the total load current drawn collectively by computer 2, monitor 3, printer 4, and lamp 5 through board 1. Device 46 includes a switch 47 that is mounted externally to housing 6 for allowing the user to manually reset device 46 in the event that the isolation occurs.

Housing 6 includes a pair of LED's 48 and 49 for providing a visual indication to the user of the availability of the power supply to sockets 12,13, 14 and 18. More particularly, LED 48 is connected across the earth and the active line intermediate device 46 and relay 15. LED 48 illuminates if pin 8 is connected to the mains supply, switch 44 is closed and device 46 is closed. That is, LED 48 indicates to the user that board 1 is connected to mains power. LED 49, on the other hand, is connected across pin 8 and the active line intermediate relay 15 and sockets 12,13 and 14. LED 49 illuminates if pin 8 is connected to the mains supply, switch 44 is closed, device 46 is closed and one or more of contacts 16 and switch 45 are closed. That is, LED 49 indicates to the user that board 1 is connected to mains power and that power is available at controlled sockets 12,13 and 14.

Each LED will have a current limiting resistor (not shown) or other circuitry in series with the LED to ensure that the voltage and current delivered to each LED is limited to a value that will not damage the LED.

In other embodiments alternative indicators to LED's 48 and 49 are used, such as neons, incandescent lamps, or other devices.

Initially, with the configuration shown in Figure 1, the user ensures that plug 7 is connected to the mains supply by inserting pins 8,9 and 10 into a mains wall outlet. If the outlet is active, and switch 44 is in the closed state, then power will be made immediately available to socket 18, as this is independent of the controlled nature of the other sockets. That is, the user is free to switch computer 2 on from the present inactive state. For the purposes of this example it is assumed that switch 45 is in the open position so that the supply of power to sockets 12,13 and 14 is controlled by the energisation of coil 17. Accordingly, in the state described-that is, with computer 2 not being on-then there will be an absence of supply voltage, and hence an absence of supply current, in wires 40 and 41 of cable 34. In turn, coil 17 will not be energised and contacts 16 will be in the open state. That being the case, monitor 3, printer 4, and lamp 5 will be isolated from the mains supply. However, when the user activates computer 2,

the relevant hardware, including port 36, will be initialised for operation and the supply voltage will be applied across wires 40 and 41. That being the case, coil 17 will energise and subsequently close contacts 16. This then connects sockets 12,13 and 14 to the mains supply. Following from this, monitor 3, printer 4, and lamp 5 will also be connected to the mains supply.

With the power now available to the other loads, they are operated by the user as their respective functionalities allow. So, for example, printer 4 is turned on and made available for receiving print jobs from computer 2. If the printer was left with its manual ON/OFF switch in the ON state, then upon socket 12 being connected to the mains, it would automatically commence initialisation upon closure of contacts 16 : Similar comments apply to monitor 3 and lamp 5.

When the user wishes to shut down computer 2, this occurs in the usual manner, through actuation of the relevant software or hardware. At some time during the shut down procedure the supply voltage across wires 40 and 41 will be removed. The exact timing will be somewhat dependent upon the nature and configuration of computer 2. In any event, when it does occur, coil 17 will no longer be energised and contacts 16 will return to the open state. Accordingly, sockets 12,13 and 14 will become isolated from mains supply and monitor 3, printer 4, and lamp 5 will cease to function. This ensures that in the absence of the operation of computer 2, the other loads will not draw any mains power.

This is advantageous as it allows for a minimisation of power consumption as well as increasing the convenience of gaining that minimisation. For example, if one or more of the loads is disposed in an awkward position there is considerable disincentive for the user to shut the load down completely when it is not in use. This preferred embodiment provides the user with a minimum of actions that result in the maximal of power savings.

Board 1 is easily converted to a standard power board should it be later applied to a situation where that other functionality is required. This is achieved by closing switch 45.

While this embodiment has made use of a desktop computer, in other embodiments use is made of a laptop computer, computer peripheral device, a palm top device, a server, a multimedia device, or any other computing device. Still further embodiments make use of other electric appliances such as a refrigerator, stove, lamp or

the like, where those devices have an interface for providing a voltage sufficient to drive the switching functionality of the preferred embodiments.

A further embodiment of the invention is illustrated in Figures 3,4 and 12. In this embodiment, a power board 51 is also used for connecting a load (not shown) to a primary power source in the form of a mains supply. Board 51 includes a rectangular prismatic plastics sealed moulded housing 52 and an input connector in the form of a domestic three pin plug 53 that is mounted to and extends from housing 52 for electrically connecting to the power source. An output connector in the form of a domestic three pin socket 54 is mounted to and extends into housing 52 for selectively electrically connecting to the load.

A switch, in the form of the contacts 55 of a relay 56, is physically disposed within housing 52 and electrically disposed between the active pin of plug 53 and the active pin of socket 54 for changing between an open state, as illustrated in Figure 12, to disconnect, and a closed state to connect, the power source and the load. As with the Figure 1 embodiment, board 51 includes an actuator, in the form of a relay coil 57, that is located within housing 52 and which is supplied with a power signal from a remote electric device such as a computer. Similarly also to the Figure 1 embodiment, the actuator is responsive to the signal ceasing to progress the switch to the open state.

Power board 51 includes only a single three pin socket 54, as opposed to the multiple sockets included in the Figure 1 embodiment. That is, board 51 provides only a single control point, although this can be used to feed power to a plurality of loads that are piggybacked with socket 54.

Housing 52 includes a USB port 58 for selectively receiving a complementary USB cable (not shown). The cable has four pins that are labelled 1,2, 3 and 4. Pins 1 and 4 carry the supply voltage and current, while pins 2 and 3 are for data transmission. The cable is, at its other end, connected with the remote electric device. As with the earlier described embodiment, coil 57 is responsive to the availability of a power supply voltage via the USB cable for maintaining contacts 55 in the closed state and thereby allowing power to be passed between plug 53 and socket 54. When the USB cable supply voltage is not present across pins 1 and 4-for example, if the computer is turned off or if the USB cable is removed from port 58-then contacts 55 move to open state to electrically disconnect plug 53 and socket 54. That is, the supply of power by board 52 is, in effect, controlled by the state of the computer or other device that is connected to the remote end of the USB cable. As with the earlier described embodiment, the controlling device does

not have to be a computer, but could be a far less sophisticated device such as a monitor, lamp, or other electric appliance.

It will be appreciated that board 51 is not responsive to any data signals that are present between pins 2 and 3 of port 58. In other embodiments (not shown) board 51 contains circuitry that is responsive to the data signals to allow more complex interactions such as time specific operation of board 51, password protection for the operation of board 51 or other functionality. In those embodiments where that circuitry requires more than 100 mA of supply current, it draws additional current either from the USB bus-that is, with that bus operating in the high power mode-or directly from the power board.

This embodiment is particularly advantageously applied to provide power to a computer peripheral such as a printer for a computer. That is, the printer power cable is inserted into socket 54 and the USB cable connected at its distal end to the corresponding USB port of the computer. The printer includes a housing and a power switch located on that housing for allowing the user to actuate and de-actuate the printer.

In this embodiment, that power switch is left in the on state. Accordingly, when the computer is turned on, board 51 allows mains power to be provided to the printer, which automatically powers up. When the computer is shut down, there is no longer a supply voltage provided to the USB cable and, as such, board 51 automatically electrically disconnects the printer from the mains supply. This provides the user with the convenience of automatically shutting down the printer without having to manually toggle the printer's power switch. This also ensures that when the computer is not operating that the printer will not draw any mains power.

In other embodiments, the circuitry of Figure 12 is integrated into a computer peripheral. In this case, reference is made to a peripheral such a printer (not shown) that has plug 53 connected in a mains outlet. More particularly, the printer uploads data for printing via the USB cable via pins 3 and 4. As with the embodiment of Figures 3 and 4, that same cable provides a voltage supply at pins 1 and 4 for allowing the control of relay 56 by a remote computer. In this embodiment, the computer is also connected to the distal end of the cable. When the computer is shut down there is no need to have the printer switched on. The combination of this embodiment automatically accommodates this requirement as when the computer is off, the voltage will no longer be provided across pins 1 and 2 of port 58 and, as such, contacts 55 will open and the printer will be disconnected from the mains supply.

Another embodiment of the invention, in the form of a power board 61, is shown in Figure 5 where corresponding features are denoted by corresponding reference numerals. The circuitry contained within housing 52 is also that which is illustrated in Figure 12 and, as such, the functionality is identical to board 51.

Board 61 includes a flexible lead 62 that connects plug 53 to housing 52. This allows housing 52 to be disposed other than directly adjacent to the mains outlet.

A further embodiment of the invention is illustrated in Figure 6 where, again, corresponding features are denoted by corresponding reference numerals. More particularly, a board 71 includes three additional like sockets 72,73 and 74 that are connected electrically in parallel with socket 54. The four sockets selectively receive complementary plugs from respective loads (not shown) for allowing connection of the loads to the mains supply.

As the four sockets 54,72, 73 and 74 are in parallel, the action of socket 58 results in the simultaneous availability of mains power at those or, alternatively, the simultaneous unavailability of mains power to the sockets. That is, a single control source that provides the power signal to pins 1 and 4 of connector 58 controls the operability of the supply of mains power to up to four separate loads.

Reference is now made to Figure 7 where there is illustrated a further embodiment of the invention in the form of a power board 81. Again, corresponding features are denoted by corresponding reference numerals. Board 81 includes, in addition to the parallel connected sockets 54,72 and 73, two further sockets 82 and 83 that are both connected directly to the mains supply. That is, the active pin of sockets 82 and 83 is electrically connected to the active wire of lead 62 on the mains side of contacts 55. That being the case, board 81 includes three sockets-sockets 54,72 and 73-that are controlled via relay 56 and two sockets-sockets 82 and 83-that operate independently of connector 58. Accordingly, a load that sources main power via either of sockets 82 and 83 is able to so source that power regardless of the state of contacts 55. However, the remaining sockets will only allow the respective associated loads to be supplied with mains power when there is a voltage across pins 1 and 2 of port 58 and, hence, contacts 55 of relay 56 are in the closed state.

Board 81 also includes an indicator lamp in the form of an LED 84 that is mounted to housing 52 adjacent to sockets 54,72 and 73 for signalling to a user the presence of the supply voltage across pins 1 and 4 of relay 56. That is, LED 84, when

illuminated, indicates to the user that the controlling electrical device is operative and that, therefore, the loads connected via sockets 54,72 and 73 have mains power available to them. To provide the user with clarity, sockets 54,72 and 73 are contained within a border 124 that is clearly marked on housing 52.

LED 84 toggle between an illuminated and an unilluminated state in accordance with the voltage across pins 1 and 4.

Also included on board 81 is an interface output in the form of a USB Type A socket 85 that is connected within housing 52 to pins 1,2, 3 and 4 of port 58. This allows the signals being transmitted through the USB cable to be passed on to another device such as a printer. This allows a single USB port on the controlling computer to send data signals to the peripheral device via pins 3 and 4, while the power signal across pins 1 and 4 functions to control the accessibility of power to sockets 54,72 and 73. This functionality is important in embodiments where the controlling device does not have a USB port that is able to be dedicated to the control of board 81.

Reference is now made to Figure 8 that illustrates a further embodiment of the invention that includes a board 91 that has all the functionality of board 81. That is, socket 82 operates independently of relay 56, while sockets 54,72 and 73 are dependent upon the state of contacts 55 as to whether mains power is available to the respective loads. It should be noted that, in this embodiment, USB ports 58 and 85 are mounted to a sidewall of housing 52 as opposed to the top wall of that housing. Functionally, however, there is no difference to the operation of these ports.

In addition, board 91 includes a master power switch 92 that is mounted to the top wall of housing 52 and which is manually toggled by a user between an on and an off state. In the on state, mains power is available to sockets 82. It is only if contacts 55 are in the closed state that mains power is available to sockets 54,72 and 73. However, with switch 92 in the off state, the mains power is not available to any of the sockets and therefore the respective loads are also disconnected from the mains supply.

By toggling switch 92 to the off and the on state respectively, the user disables and enables the operation of board 91.

Board 91 also includes a user operable power override switch 93 that mounted to the top wall of housing 52 adjacent to switch 92. Switch 93 is also manually toggled by a user between an on and an off state. When toggled to the on state the control functionality provided by relay 56 is disables and the otherwise dependent sockets 54,72

and 73 are connected directly to the active wire of lead 62. This is, however, contingent upon switch 92 also being in the on state.

Board 91 includes a overload protector (not shown) within housing 52 that is electrically interposed between lead 62 and switch 92 for preventing inadvertent current overloading of the board. That is, if a preset maximum current threshold is exceeded, the overload protector will trigger and electrically isolate all the sockets from the mains supply, regardless of the state of any of the switches and contacts.

The overload protector includes a manual reset button 94 that is mounted to and which extends outwardly from the sidewall of housing 52. In the event that the overload protector triggers, the user is able to provide a manual reset by depressing button 94. In other embodiments use is also made of a power line filter in series with the overload protector. Still further embodiments make use of surge protection, or any combination of surge protection, overload protection, and power line filtering.

Board 91 also includes a power indicator in the form of an LED 95 that is mounted to the top wall of housing 52. This LED illuminates when all the following conditions are satisfied : 1. Power is available at plug 53; and 2. Switch 92 is in the on state; and 3. The overload protector is in the normal-that is, the non-isolating-state.

A further power board 101 is illustrated in Figure 9 and includes the functionality of board 91, but with two parallel and co-extensive arrays of sockets 82,54, 72 and 73, as opposed to a single array as provided by board 91. In addition, the arrays of sockets on board 101 include respective extra power sockets 102 and 103 that are disposed adjacent to, but spaced part from, sockets 73.

Sockets 102 and 103 are best used with those loads having transformer blocks (not shown) that include a sealed power supply that is incorporated into the plug that is to be inserted into these sockets. That is, the transformer blocks are usually more bulky than a standard plug and usually partially obscure at least on adjacent socket on the board. However, as sockets 102 and 103 provide an increased and non-uniform spacing with respect to the spacing between other adjacent sockets, the use of two transformer packs is greatly facilitated without compromising the number of other loads able to be accommodated by board 101.

It will be appreciated that the transformer blocks referred to above are also commonly known as plug packs.

As will be appreciated by those skilled in the art, that the spacing may be altered between any sockets on power board 101 so as to facilitate the installation of more transformer blocks. For example, the spacing may be increased between sockets 72 and 73, between 54 and 72, and between 82 and 54.

Board 101 also includes tabs 104 and 105 to allow the board to be easily mounted to a wall, desk or other object.

Reference is now made to Figure 10 which illustrates a cable 110 for extending between any one of the boards described above and the remotely located computer that controls the respective boards. Cable 110 is a USB cable having at one end a USB Type B plug 111 to engage with port 5 8. The other end of cable 110 has a USB Type A plug 112 to connect to the interface of the computer or other electric device that controls the ON/OFF function. An electrical interface cable 113 connects the two plugs together.

For a USB connection, cable 110 has two power wires (not shown) and two signal wires (not shown). Other suitable USB cables include a conducting cable shield. In other embodiments, one end of cable 110 is captive within housing 52 and, as such, the Type B plug 111 and port 58 combination is not required.

An alternate interface cable 115 is shown in Figure 11, where corresponding features are denoted by corresponding reference numerals. This cable, like cable 110, is intended to connect the respective board to the controlling device, in whatever form the latter may take. Cable 115 includes a first end having a USB Type B plug 111 that is complementarily received within the port 58 of the relevant board. Another end of cable 110 includes a 5-pin DIN plug 116 that is received within a complementary port in a computer. The third end of cable 110 includes a 5-pin DIN socket 117 that is wired in a pass-through mode and which is inserted into a complementary port in a keyboard device (not shown). That is, the required voltage or signal levels for controlling the power board are derived from the connections in socket 116 and passed down the interface cable 111.

At the same time, cable 111 continues to pass the usual data between the keyboard device and the computer. That is, the use of cable 115 does not need a separate USB port. In some embodiments this is an important feature as there is either no USB associated with the computer or any ports are being used for other applications.

Reference is now made to Figure 13 that provides a schematic illustration of the electrical circuit of board 81 of Figure 7. Once a voltage is detected across pins 1 and 4 of port 58-that is, once the controlling computer device is turned on-LED 84 is illuminated. In this embodiment the voltage provided by the USB interface is approximately 5.0 volts with a current capacity of about 100mA.

Effectively simultaneously with the illumination of LED 84, the contacts 55 of relay 56 will close to automatically make mains power available to sockets 54,72 and 73. Contacts 55 are rated to accommodate the current and voltage levels to which they are exposed during use in board 81.

In other embodiments use is made of an alternative switching device to relay 56.

For example, in further embodiments use is made of a solid-state circuit to affect the switching.

The active mains power supply enters the device via an input pin 121. That pin is permanently electrically connected to the corresponding active pins for sockets 82 and 83. However, the active pins for sockets 54,72 and 73 are connected to pin 121 via contacts 55 and, accordingly, are only electrically connected when those contacts are in the closed state.

The neutral voltage from the mains supply is connected with a neutral input pin 122.

This pin is directly connected to all the corresponding neutral pins on all the outlet sockets.

The electrical earth from the mains supply is connected with an input earth pin 123 and is also directly connected to all the corresponding earth pins on all the outlet sockets.

It will be appreciated that pin 123 is also connected to any components of board 81 that require an earth connection. For example, in some embodiments, housing 52 includes a metal chassis that is connected to pin 123.

Although the embodiment shown in Figures 7 and 13 includes two outlet sockets that are independent of relay 56 and three outlet sockets that are dependent upon relay 56, in other embodiments different combinations of sockets are used. For example, one embodiment includes a single independent socket and three dependent sockets. As will be appreciated by those skilled in the art, from the teaching herein, that many other alternatives are possible.

Turning to Figure 14, there is illustrated, in schematic form, an alternative power board 131 that is similar to power board 51 of Figures 3 and 12. For convenience, corresponding features will be denoted with corresponding reference numerals. More

particularly, board 131 includes relay 56 that has as additional set of contacts 132 to allow automatic switching of both an active voltage feed 133 and a neutral voltage feed 134.

This provides a greater degree of isolation and protection of the attached peripherals and/or appliances. An earth feed 135 is permanently electrically connected to the corresponding earth pin on the outlet socket 54.

Reference is now made to Figure 15 that illustrates schematically a solid state electrical circuit 141 that is used, in some embodiments, as a substitute for relay 56.

That is, circuit 141 functions as an automatic power ON/OFF switch. Circuit 141 includes an optically coupled bilateral triac driver 142 having an internal LED 143 that is coupled with an internal triac 144. A further triac 145 includes a main terminal 1 that is designated by reference numeral 146 and which is electrically connected to the active pins 147 of the outlet sockets that are controlled by the power board in which circuit 141 is contained. Triac 145 also includes a main terminal 2 that is designated by reference numeral 148 and which is electrically connected to the active pin, say, pin 121, of plug 53. Triac 145 also includes a gate 149 that, when biased, progresses triac 145 from a non-conductive to a conductive state.

As shown, triac 144 is connected in series with a current limiting resistor 150 between terminal 148 and triac 144. Another current limiting resistor 151 is connected in series with LED 143.

LED 143 is connected across pins 1 and 4 of port 58 so that when a power signal is present the LED is illuminated. Resistor 151 ensures that, for the supply voltage across pins 1 and 4 that the current is limited to a value that will not damage LED 143.

It also ensures, during the presence of the supply voltage across the relevant pins, that LED 143 will be illuminated so as to progress triac 144 to a conductive state. It will be appreciated that the current required to maintain LED 143 in an illuminated state is generally less than would be required for a relay of corresponding capacity.

With triac 144 in the conductive state, the voltage present at gate 149 rises and, once exceeding the relevant threshold, progresses traic 145 from a non-conductive to a conductive state. When in the latter state, current is available to flow from the mains supply-that is, in use, connected with pin 121-to the load-that is, in use, connected with pin 147.

Triac 145 is chosen to cope with the current and voltage loads that the associated board is designed to handle.

In other embodiments alternative solid state components are used.

Another embodiment of the invention is schematically illustrated in Figure 16.

More particularly, there is illustrated an electrical device 161 that draws power from a mains supply (not shown). The electrical device may be, for example, a peripheral device such as a printer. A power supply 162 is located within the device 161. An input connector 163, in the form of a three pin socket, provides a point of connection to the mains supply. An automated switch, in the form of a relay 56, is disposed within device 161 between connector 163 and power supply 162. Operating similarly as described with reference to the Figure 12 embodiment, relay 56 moves between an open or non-conductive state and a closed or conductive state for respectively electrically disconnecting and connecting connector 163 and power supply 162. This, in turn, respectively electrically disconnects and connects the power supply and the mains supply. Relay 56 is responsive to a remote control signal from a computer device connected to connector 58 for moving to the closed state.

Power supply 162 may have many forms, including a transformer and rectifier, or a switch mode power supply. Power supply 162 typically provides one or more low voltage DC outputs via connection 166.

The remote control signal is a power signal that is received by a USB port 58 that is mounted to device 161. The port is connected to a computer via a USB cable (not shown). In other embodiments a USB cable directly terminated inside the housing may replace connector 58.

Connector 58 receives a data signal on separate conductors 167 and 168 to the power signal. In this embodiment, circuitry 164 in device 161 is responsive also to the data signal for exchanging data from a computer attached to connector 58. It will be appreciated that the term"computer"includes not only a stand alone computer such as that illustrated, but also a number of interlinked computers, a computer network, portable computing device, etc...

Connector 163 includes an active 169, neutral 170 and earth connection 171 from the mains power. In other embodiments only connections 169 and 170 may be required.

In further embodiments, the circuitry contained in the area enclosed by dotted line 165 may be mounted in a separate housing than the circuitry 164. In this embodiment power connection 166 and data connections 167 and 168 may be supplied by an external cable either directly terminating within each housing, or using corresponding plugs and sockets at one or both ends of the cable.

In other embodiments, connector 163 may be replaced by a directly connected power cable, terminated at the distal end by a standard domestic power plug.

In still further embodiments overload protection, surge protection, or power line filtering may be included, operating similarly as described with reference to the Figure 2 embodiment In other embodiments relay 56 may be replaced by circuitry 141.

The embodiments illustrated in the drawings include sockets and plugs for use with the standard mains outlets that are used in Australia. However, the invention is also applied, in other embodiments, with mains outlets in other jurisdictions through incorporating the corresponding plug and socket combinations for those jurisdictions.

Moreover, the illustrated embodiments include sockets and plugs of the three pin variety with separate paths corresponding to the active, neutral and earth supplies. However, the invention is also applied, in other embodiments, with mains outlets that have only the two pin variety, those being the active and neutral supplies, in that the earth path is omitted.

The preferred embodiments described above make use of a power signal that is inherently supplied by a USB connection with a computer or other electrical device.

However, other forms of power signals are available and are used in other embodiments.

For example, in the case where the electrical device is a computer, there are a number of possible interfaces including: a serial RS232 compatible interface; a parallel interface; a Firewire interface; and a keyboard interface.

In some embodiments the invention interacts with a USB hub. This type of hub is an active electronic device that plugs into the USB socket of the computer or another device or USB hub. For example a hub of this kind could be plugged into socket 85 of Figure 7 or Figure 13. The hub provides a multiple of additional USB sockets for use by a corresponding number of USB devices.

The hub provides a form of daisy chaining, although electronics are required in the hub as the USB interface alone cannot be physically and electrically paralleled.

Such a USB Hub is able to be inserted at any point in the USB cables shown in the drawings which, in turn, adds a plurality of additional USB ports.

Where use is made of such a hub, it is preferred that the power board is either directly connected to the computer, or is at least upstream of the hub. In one embodiment (not shown) the hub is incorporated into the housing of a power board according to the invention.

Although this invention has been described with reference to specific examples, it will be appreciated by those skilled in the art that it may be embodied in many other forms.