The present invention is advantageously, but not exclusively, applicable to domestic lamp actuation, which will be referred to here-in-after in the following discussion, without however renouncing to its general aspect.

The present invention is also applicable for controlling any type of electric load in an office, such as photo-copying machines, type-writers, computers, etc.; or for controlling electric devices in a laboratory or workshop, work benches to which electrical tools-such as welders, meters, etc.-are connected.

BACKGROUND ART It is known that, to actuate domestic lamp switching on and off, the following control devices can be. used, at present: circuit breakers, switches, switched stepped relays and sequence stepped relays.

The choice of the control device to be used depends on the number of locations from where the actuation of lamp switching on or off is desired. Actually, switching on and

off of one lamp can be controlled by one circuit breaker from just one location, one lamp switching on and off can be actuated by two switches from two locations, one lamp switching on and off can be actuated by a switched stepped relay and a plurality of pushbuttons from as many locations as the pushbuttons used, and two lamp sets switching on and off can be actuated by a sequence stepped relay and only one pushbutton according to the sequence for which the relay is preset.

It is also known that, when you leave a house, you need to go through all its rooms in order to check that all lamps are off and/or switch off those lamps that are on.

A growing need is therefore exists relating to the availability of control devices allowing simultaneously switching off of all lamps which are on in a house from a single location.

In the past, particularly in hotels, the solution was adopted to use a main switch, arranged near the room entrance door, to allow the customer or cleaning staff to switch off all lamps when going out of the room.

This solution is, nevertheless, unsuitable for a house both because when going back home and switching on of the main switch, all lamps previously left on would be switched off. Therefore single switches would have be actuated to switch off the various lamps which were on and because you

would have to use two different supply lines-one for the lamps and one for the sockets-in order to prevent household electrical devices (e. g. freezers or refrigerators) from remaining without a power supply for long periods of time.

DISCLOSURE OF INVENTION An object of the present invention lis therefore to provide a control device and related electrical system which allow simultaneously switching off of all lamps in a house from a single location in a simple and economical way.

According to the present invention, an electric load control device is provided as defined in Claims 1 and 16.

According to the present invention, an electric system is provided as defined in Claims 51 and 66.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention some preferred embodiments thereof are described here below, merely as a non-limiting example, with reference to the enclosed drawings, wherein: -Figure 1 is a diagram of an electrical system using a control device according to a first embodiment of the present invention; -Figure 2 diagrammatically shows a section of a stepped relay belonging control device in Figure 1; -Figure 3 is a diagram of an electrical system using a control device according to a second embodiment of the

present invention; -Figure 4 is a diagram of an electrical system using a control device according to a third embodiment of the present invention; -Figure 5 is a diagram of-an electrical system using a control device according to a fourth embodiment of the present invention; -Figure 6 is a diagram of an electrical system using a control device according to a fifth embodiment of the present invention; -, Figure 7 is a diagram of an electrical system using a control device according to a sixth embodiment of the present invention; -Figure 8 is a diagram of an electrical system using a control device according to a seventh embodiment of the present invention ; and -Figure 9 is a diagram of an electrical system using a control device according to an eighth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Figure 1 shows an electrical system using control devices according to a first embodiment of the present invention.

The electrical system, denoted, as a whole, by la, includes: first, second and third lines 2,3 and 4, respectively set to first, second and third potentials; a reset line 6, connected to first line 2 through a reset z a <BR> <BR> <BR> <BR> <BR> <BR> <BR> . e<BR> <BR> <BR> <BR> <BR> <BR> <BR> a<BR> e<BR> <BR> a o alj : ct -de ns <BR> <BR> <BR> <BR> <BR> <BR> <BR> g<BR> ig<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> r<BR> <BR> <BR> <BR> <BR> <BR> <BR> LBrT<BR> r de de rp rp <BR> <BR> <BR> <BR> <BR> <BR> <BR> y<BR> y y r ), Ey :

pushbutton 8, properly arranged near the house exit; and a plurality of lamps 10, actuated by corresponding control devices, these devices being implemented according to the first embodiment of the present invention and collectively denoted by 12a (only two of them being shown in Figure 1), which are connected to lines 2,3,4 and 6 and are located in the various rooms in the house.

In particular, in the following discussion related to the first embodiment of the present invention, reference will be made, in a non-limiting way, to an electrical system la wherein, between first and second lines 2,3, as well as between second and third lines 3,4, there are respective alternated potential differences whose values are the same or different from one another, for instance 12 V and 220 V AC.

Each control device 12a has a first pin 14, connected to reset line 6; a second pin 16, connected to third line 4 through a corresponding lamp 10; and a third pin 18, connected to second line 3.

Each control device 12a includes a stepped relay 20, of a known type, provided with a control pushbutton 22, a power contact 24, and a coil or winding 25 (shown schematically), having a first terminal 26, connected to first pin 14 through a rectifying diode 28, and a second terminal 30, connected to second pin 16 and, through its own power contact 24, to third pin 18.

In particular, rectifying diode 28 has an anode terminal 28a, connected to first pin 14, and a cathode terminal 28b, connected to first terminal 26 of coil 25, and defines a half-wave rectifier used to allow energizing of coil 25 of same stepped relay 20 only during a first half-wave of the supply voltage, in particular, with the connections shown in Figure 1, lis the positive half-wave.

A further purpose of rectifying diode 28 is to prevent stepped relay 20 from spuriously switching when, in the electrical system 1, in addition to the above-described reset pushbutton 8, also additional reset pushbuttons are arranged for the purpose actuating only corresponding lamp set 10 switching off, as will be described in more detail herein below.

Each control device 12a also includes a re-circulation diode 32, located between first and second terminals 26,30 of coil 25, and having, in particular, an anode terminal 32a connected to second terminal 30, and a cathode terminal 32b connected to first terminal 26, and its purpose being to avoid switching problems of the stepped relay 20 itself during the second half-wave of the supply voltage, in particular, the negative half-wave.

As schematically shown in Figure 2, stepped relay 20, whose useful parts only are shown for a better understanding of the present invention, includes a shell 40, wherein coil 25 ; a first support means 42 for rectifying and re-

circulation diodes 29,32 (not shown in the Figure), a second support means 44 for power contact 24, a toothed wheel 46, that is stepwise rotationally movable around its axis, coupled, in a conventional and not shown way, to coil 25 and to power contact 24, and, through a leverage 48 and a small anchor 50, to control pushbutton 22 and adapted to open or close same power contact 24 are housed. In particular, toothed wheel 46, also schematically shown with a dashed line in Figure 1, trips whenever either an electric current passes through coil 25 or control pushbutton 22 is pressed, and each trip causes the power contact 24 to toggle between its open/close states.

The operation of electrical system la will be now described with reference to actuation of one just of the lamps 10.

Each control device 12a works as a circuit breaker, i. e. allows corresponding lamp 10 to be switched on from a single room location.

Actually we consider an initial condition wherein power contact 24 is open and consequently lamp 10 is off, on actuating control pushbutton 22, toothed wheel 46 of stepped relay 20 trips, thereby controlling power contact 24 closure.

In this way, a first current path is defined between second and third lines 3,4 through same power contact 24 and lamp 10, which consequently switches on.

By further actuating control pushbutton 22, toothed wheel 46 trips again and controls power contact 24 opening and, consequently, lamp 10 switching off.

By further actuating control. pushbutton 22, the sequence of operations restarts from the beginning with lamp 10 switching on.

Lamp 10 can be switched off, other than by control pushbutton 22, also by reset pushbutton 8. Actually, when lamp 10 is on and consequently power contact 24 is closed, reset pushbutton 8 actuation defines a second current path between first and second lines 2,3 through same reset pushbutton 8, rectifying diode 28, coil 25 of stepped relay 20 and power contact 24 and, in this way, coil 25 of stepped relay 20 is energized thus rotating toothed wheel 46 by one triggering trip. Toothed wheel 46 consequently controls power contact 24 to open and consequently lamp 10 to switch off.

On any following reset pushbutton 8 actuation (not preceded, of course, by control pushbutton 22 actuation), no current path is defined between first and second lines 2,3 through rectifying diode 28, power contact 24 and coil 25 of stepped relay 20 as power contact 24 is open. In such situations, therefore coil 25 of stepped relay 20 is not energized and consequently power contact 24 remains open and lamp 10 off.

Therefore, in this way, on each reset pushbutton 8

actuation, all lamps 10 that are on, i. e. that are connected to the control devices 12a whose stepped relays 20 have power contacts 24 closed, are automatically switched off, while those that are already off remain as they are.

The above-described reset function is made possible because, in each control device 12a, stepped relay 20 has its own power contact 24 arranged in series with its own coil 25.

Actually each power contact 24 defines a store means of the on/off operational status of corresponding lamp 10 and causes control device 12a to work in a different way according to its own status.

In particular, a closed power contact 24 indicates lamp 10 on status and permits energizing of coil 25 of corresponding stepped relay 20 by reset pushbutton 8, thus allowing lamp 10 to be switched off by same reset pushbutton 8, while an open power contact 24 indicates lamp 10 off status and prevents coil 25 of corresponding stepped relay 20 from being energized by reset pushbutton 8, thus preventing lamp 10 from being switched on by same reset pushbutton 8.

According to a not shown variation, electrical system la could provide, in addition to above described main reset pushbutton 8 that allows all lamps 10 in the house to be switched off, also local reset pushbuttons, each connected to a corresponding control devices set and being used to actuate the switching off only of those lamps 10 being controlled by corresponding control device set (e. g. a local reset

pushbutton for lamps in the bathroom, a local reset pushbutton for lamps in the kitchen, etc.).

In these systems, each control device 12a would have an additional reset pin for each local reset pushbutton to which it is connected, and each additional reset pin would be connected, at one end, to first terminal 26 of corresponding coil 25 through corresponding rectifying diode 28 and, at the other end, jointly with additional reset pins of control devices 12a controlled by same local reset pushbutton, to a local reset line connected to first line 2 through same corresponding local reset pushbutton.

In this type of electrical system, rectifying diodes 28 perform, besides half-wave rectifying function, all the additional function of preventing local reset pushbutton actuation from controlling also the switching off of those lamps 10 which are not-actuated by such pushbutton.

Actually if rectifying diodes 28 are missing, local reset pushbuttons would be directly connected to first terminal 26 of corresponding coil 25 and consequently to reset line 6, and therefore the reset actuation instruction, determined by a local reset pushbutton actuation, would be sent not only to stepped relay 20 of control devices 12a to which this local reset pushbutton is connected, but also to all the other control devices 12a through same reset line 6.

The presence of rectifying diodes 28 prevents, on the contrary, this actuation instruction from arriving also at

reset line 6, thus avoiding that, in case of use of both main reset pushbuttons and local reset pushbuttons, a local reset pushbutton actuation might control also the switching off of those lamps 10 which are not controlled thereby.

So it is clear that, if there were only one reset pushbutton 8 for all lamps 10, the circuit structure of each control device 12a could be simplified by eliminating rectifying diode 28 and re-circulation diode 32 without any effect on the operation of same control devices 12a.

Numerous modifications and variations can be made to the above described electrical system la and control device 12a without departing from the protection scope of the present invention.

For instance, rectifying diode 28 and re-circulation diode 32 of each control device 12a could also be inverted as regards the above description, i. e. rectifying diode 28 could have anode terminal 28a connected to first terminal 26 of stepped relay 20 and cathode terminal 28b connected to first pin 14, and re-circulation diode 32 could have anode and cathode terminals 32a, 32b respectively connected to first and second terminals 26,30 of stepped relay 20, and in this case coil 25 of stepped relay 20 being would be energized during the negative half-wave of supply voltage.

Moreover reset pushbutton 8 could be replaced by any other type of device being capable of simulating the function

performed by reset pushbutton 8, i. e. being able to generate, at each actuation thereof, such a reset pulse as to cause the energizing of coil 25 of stepped relay 20.

Then, differences in potential existing between second and third lines 3,4, as well as between first and second lines 2,3 could assume values other than those described or such differences of potential could be continuos instead of alternate, e. g. 12 Volt in direct current, and in this case, for rectifying diode 28, what has been said above is worth, while re-circulation diode 32 could be omitted no matter whether rectifying diode 28 is provided or not.

Moreover, first and third lines 2,4 could be connected one another in such way as to define a single line to which both reset line 6 and lamp 10 are connected.

Figure 3 shows an electrical system using control devices according to a second embodiment of the present invention, wherein parts that are identical to those of electrical system la of Figure 1 are identified by the same reference numerals.

According to what is shown in Figure 3, the electrical system, which is denoted, as a whole, by lb, also includes, in addition to lines 2,3,4 and 6 above described for electrical system la, a fourth line 5, preset to a fourth potential; and a plurality of lamps 10 and corresponding control devices, implemented according to a second embodiment

of the present invention and collectively denoted by 12b (only two of them being shown in Figure 1), which are connected to lines 2,3,4,5 and 6 and located in the various rooms in the house.

In particular, in the following discussion relevant to the second embodiment of the present invention, reference will be made, in a non-limiting way, to an electrical system 1b where, between first and second lines 2,3, as well as between third and fourth lines 4,5, there are respective potential differences alternated in differently of same or different values from one another, for instance 12 and 220 V in alternate current.

Each control device 12b has a first pin 60, connected to first line 2 through a stepped pushbutton 62; a second pin 64, connected to reset line 6; a third pin 66, connected to third line 4; a fourth pin 68, connected to second line 3; and a fifth pin 69, connected to fourth line 5 through a corresponding lamp 10.

Each control device 12b includes a stepped relay 70, provided with a control pushbutton 72, a power contact 74, an auxiliary contact 76, and a coil 25 (schematically shown) and having a first terminal 80, connected to first pin 60 through a first rectifying diode 82, and to second pin 64 through its own auxiliary contact 76 and a second rectifying diode 84, and a second terminal 86, connected to fourth pin 68.

Power contact 74 of stepped relay 70 is moreover

connected between third and fifth pin 66,69 of control device 12b.

In particular, first rectifying diode 82 has an anode terminal 82a, connected to first pin 60, and a cathode terminal 82b, connected to first terminal 80 of coil 25, while second rectifying diode 84 has an anode terminal 84a, connected to second pin 64, and a cathode terminal 84b, connected to first terminal 80 of coil 25 through auxiliary contact 76.

First and second rectifying diodes 82,84 define corresponding half-wave rectifiers used to allow energizing of coil 25 of stepped relay 70 only during a first supply voltage half-wave, in particular, with connections shown in Figure 3, the positive half-wave. A further use of first and second rectifying diodes 82,84 is to prevent stepped relay 70 from spuriously switching when stepped pushbutton 62 of another control device 12b is actuated, as will be described in more detail herein below.

Each control device 12b also includes a re-circulation diode 88, connected between first and second terminals 80,86 of coil 25 and having, in particular, an anode terminal 88a connected to second terminal 86, and a cathode terminal 88b connected to first terminal 80, the use of above re- circulation diode 88 being to avoid switching problems to stepped relay 70 during a second supply voltage half-wave, in particular, the negative half-wave.

Stepped relay 70 is structurally similar to stepped relay 20. And is different therefrom because it has a toothed wheel, schematically shown with a dashed line and denoted by 90, which trips whenever either c. oil 25 is run through by an electric current or control pushbutton 72 is pressed and performs the following actuation sequence of power and auxiliary contacts 74,76: power contact 74 and auxiliary contact 76 open; power contact 74 and auxiliary contact 76 closed; and power contact 74 and auxiliary contact 76 open.

The operation of electrical system lb will be now described with reference to the control of only one of lamps 10.

Each control device 12b, shown in Figure 3, works as a switch, i. e. allows corresponding lamp 10 to be switched on from two room locations by control pushbutton 72 and stepped pushbutton 62.

If we consider an initial condition wherein power contact 74 and auxiliary contact 76 are open and consequently lamp 10 is off, on controlling stepped pushbutton 62 a current path is defined between first and second lines 2,3 through same stepped pushbutton 62, rectifying diode 82 and coil 25 of stepped relay 70, thus causing energizing of same coil 25 and consequent rotation of toothed wheel 90 which

controls power contact 74 and auxiliary contact 76 closing and consequent switching on of lamp 10 arranged in series with same power contact 74.

A similar result can be achieved by actuating control pushbutton 72, which makes toothed wheel 90 mechanically trip.

By further actuating control pushbutton 72 or stepped pushbutton 62, toothed wheel 90 of stepped relay 70 trips again and controls power contact 74 and auxiliary contact 76 opening and, consequently, lamp 10 switching off.

By further controlling stepped pushbutton 62 or control pushbutton 72, the sequence restarts from the beginning with lamp 10 switching on.

Lamp 10 can be switched off, by control pushbutton 72 and stepped pushbutton 62, as well as by reset pushbutton 8.

This is because, when lamp 10 is on and consequently power and auxiliary contacts 74,76 are closed, reset pushbutton 8 actuation defines a current path between first and second line 2,3 through same reset pushbutton 8, rectifying diode 84, auxiliary contact 76 and coil 25 of stepped relay 70 and, in this way, the coil 25 itself is energized and rotates toothed wheel 90 by one triggering trip. Toothed wheel 90 consequently controls auxiliary contact 76 and power contact 74 to open and therefore lamp 10 to switch off.

On any successive reset pushbutton 8 actuation (not preceded, of course, by control pushbutton 72 or stepped pushbutton 62 actuation), no current path is defined between first and second lines 2,3 through second rectifying diode 84, auxiliary contact 76 and coil 25 of stepped relay 70 because auxiliary contact 76 is open. Therefore, in such a condition coil 25 of stepped relay 70 is not energized and consequently auxiliary contact 76 remains open, as well as power contact 74, and lamp 10 is off.

Therefore, in this way, on each reset pushbutton 8 actuation, all lamps 10 that are on, i. e. connected to control devices 12b whose stepped relays 70 have auxiliary contacts 76 closed, are automatically switched off, while the ones that are already off remain as they are.

The above described reset function is made possible in this embodiment because auxiliary contacts 76 are arranged between reset pushbuttons 8 and corresponding stepped relays 70. Each power contact 76 defines a storage means of the on/off operational status of corresponding lamp 10 and causes corresponding control device 12b to work in a different way according to its own status.

In particular, a closed power contact 76 indicates lamp 10 on status and permits energizong of coil 25 of the corresponding stepped relay 70 by reset pushbutton 8, thus allowing lamp 10 to be switched off by same reset pushbutton 8, while an open auxiliary contact 76 indicates lamp 10 off

status and prevents coil 25 of corresponding stepped relay from being energized by reset pushbutton 8, so inhibiting lamp 10 to be switched on by same reset pushbutton 8.

As said above, first and second rectifying diodes 82,84 of each control device 12b are used to prevent respective stepped relay 70 from improper switching when stepped pushbuttons of other control devices 12b are actuated.

In particular, if rectifying diodes 82,84 are absent, the actuation of stepped, pushbutton 62 of a first control device 12b causes the energizing of coil 25 of respective stepped relay 70 and consequently respective auxiliary contact 76 and respective power contact 74 closing, so switching on of corresponding lamp 10.

Whenever actuation of stepped pushbutton 62 of a second control device 12b, in addition to first current path between first and second lines 2,3 through same stepped pushbutton 62 and coil 25 of stepped relay 70 of second control device 12b determining switching on of corresponding lamp 10, also a second current path is defined between first and second lines 2,3 through stepped pushbutton 62, and auxiliary contact 76 of second control device 12b, reset line 6 and auxiliary contact 76 and coil 25 of stepped relay 70 of first control device 12b.

This current flow causes an undesired rotation of toothed wheel 90 of stepped relay 70 of first control device

12b, controlling the opening of auxiliary contact 76 of first control device 12b and consequently an undesired switching off of lamp 10, this lamp being controlled by this control device 12b.

The presence of rectifying diodes 82,84 prevents, on the contrary, the occurrence of a second current path like the one above described between any pair of control devices 12b, so preventing a lamp 10 from undesired switching off due to the actuation of a stepped pushbutton 62 of another control device 12b.

Numerous modifications and variations can be made to the above described electrical system 1b and control device 12b without departing from the scope of the present invention.

For instance, stepped relay 70 of each control device 12b could be deprived of control pushbutton 72. In this case each control device 12b would work as a circuit breaker, i. e. would allow corresponding lamp 10 to be switched on from only one room location by stepped pushbutton 62.

Or, electrical system lb could be deprived of stepped pushbutton 62 and therefore control devices 12b could be deprived of corresponding rectifying diodes 82,84 and corresponding re-circulation diodes 88. Therefore, also in this case, each control device 12b would work as a circuit breaker.

Or, in place of only one stepped pushbutton 62, more stepped pushbuttons 62 could be connected to each control device 12b, these stepped pushbuttons 62 being arranged in parallel between themselves, in combination with control pushbutton 72 or not. In this case it would be possible to actuate lamp 10 switching on from more room locations.

Then, similarly to what is described above for electric system la, electric system 1b too could include, in addition to main reset pushbutton 8, more local reset pushbuttons. In this case each control device 12b would be provided with an additional reset pin for each local reset pushbutton it is connected to, and each additional reset pin would be connected, at one end to cathode terminal 84b of second rectifying diode 84 through a corresponding rectifying diode identical to the rectifying diode 84 itself, and at the other end to the corresponding local reset line connected to first line 2 through the corresponding local reset pushbutton.

Moreover, rectifying diodes 82,84 and re-circulation diode 88 of each control device 12b could also be inverted as regards the above description. In this case coil 25 of stepped relay 70 would be energized during the negative half- wave of supply voltage.

Moreover, locations of rectifying diode 84 and auxiliary contact 76 could be exchanged, and thus rectifying diode 84 could have cathode terminal 84b connected to first terminal 80 of coil 25 and anode terminal 84a connected to second pin

64 through auxiliary contact 76.

Moreover, similarly to what is described above for lines 2,3,4 of electric system la, differences in potential existing between first and second lines 2,3, and between third and fourth lines 4,5 have different values than those described above and such potential differences could moreover be direct in place of alternate, e. g. 12 Volt in direct current. In this case re-circulation diode 88 and rectifying diode 82 could be omitted.

Moreover first line 2 could be connected to one line between third and fourth lines 4,5 in order to jointly define a single line, as well as second line 3 could be connected to that line which is not connected to first line 2 in order to jointly define a single line.

Connection of first line 2 to one line out of third and fourth lines 4,5 is fully independent from connection of second line 3 to the line which is not connected to first line 2, and the other way round. This provides electrical system lb with high flexibility in use.

Also in electrical system lb, moreover pushbutton 8 could be replaced by any device capable to operate as reset pushbutton 8.

Finally, each lamp 10 could be connected between third pin 66 of corresponding control device 12b and third line 4,

and therefore fifth pin 69 could be directly connected to fourth line 5.

Figure 4 shows an electrical system using control devices according to a third embodiment of the present invention, where parts that are identical to those of the electrical systems complying with previous embodiments are identified by the same reference numerals.

According to what is shown in Figure 4, the electrical system, which is designed, as a whole, with lc, includes, in addition to the above-described lines 2,3,4 and 6 for electrical system la, a plurality of lamps 10 and corresponding control devices, these devices being implemented according to a third embodiment of the present invention and collectively designed with 12c (only two of them being shown in Figure 1), which are connected to lines 2,3,4 and 6 and located in the various rooms in the house.

Each control device 12c has a first pin 100, connected to reset line 6; a second and third pin 102,104, connected to third line 4 through corresponding lamps 10; and a fourth and fifth pins 106,108, connected to second line 3.

Each control device 12c includes a stepped relay 110, provided with a control pushbutton 112, first and second power contacts 114,116 and a coil 25 (schematically shown), having a first terminal 118, connected to first pin 100, and a second terminal 120, connected to fourth pin 106, through a

first coupling diode 122, and its own first power contact 114, and to fifth pin 108, through a second coupling diode 124, and its own second power contact 116. Intermediate node 126, located between first coupling diode 122 and first power contact 114, is also connected-to second pin 102, while intermediate node 128, located between second coupling diode 124 and second power contact 116, is also connected to third pin 104.

In particular, first coupling diode 122 has an anode terminal 122a connected to second terminal 120 of coil 25, and a cathode terminal 122b connected to first intermediate node 126, while second coupling diode 124 has an anode terminal 124a connected to second terminal 120 of coil 25, and a cathode terminal 124b connected to second intermediate node 128.

Uncoupling diodes 122,124, also define respective half- wave rectifiers used to allow the energizing of coil 25 of same stepped relay 110 only during a first supply voltage half-wave, in particular, during the positive half-wave.

Each control device 12c also includes a re-circulation diode 130, arranged between first and second terminals 118, 120 of coil 25 and having, in particular, an anode terminal 130a connected to second terminal 120, and a cathode terminal 130b connected to first terminal 118, whose use is to avoid switching problems to stepped relay 110 during second supply voltage half-wave, in particular, during the negative half-

wave.

Stepped relay 110 is structurally similar to stepped relay 20. The only difference is that it has a toothed wheel, schematically shown with a dashed line and denoted by 132, that trips whenever either coil 25 is run through by an electric current or control pushbutton 112 is pressed and performs the following actuation sequence of power contacts 114,116: first and second power contacts 114,116 open; first and second power contacts 114,116 closed; first power contact 114 open and second power contact 116 closed; first power contact 114 closed and second power contact 116 open; and first and second power contact 114,116 open.

The operation of electrical system lc will now be described with reference to actuation of only one of the lamps 10.

Each control device 12c works sequentially, i. e. allows the sequential switching on of corresponding pair of lamps 10 from only one room location.

Actually if we consider an initial condition where power contacts 114,116 are open and consequently lamps 10 are off, on controlling control pushbutton 112, toothed wheel 132 of stepped relay 110 trips, controlling power contacts 114,116

to close. In such way a first and second current path are defined between second and third lines 3,4 through power contacts 114,116 and corresponding lamps 10, connected to them in series. Consequently, these lamps are switched on.

By controlling control pushbutton 112 again, toothed wheel 132 trips again and contrdls first power contact 114 to open and consequently switching off lamp 10, connected thereto.

By controlling control pushbutton 112 once again, toothed wheel 132 trips once more and controls first power contact 114 to close and consequently lamp 10 connected thereto to switch on, and power contact 114 to open and consequently switching off lamp 10, connected thereto.

By further controlling control pushbutton 112, toothed wheel 132 trips again and controls both power contacts 114, 116 to open and consequent switching off of both lamps 10.

By controlling control pushbutton 112 again, the sequence of operations restarts from the beginning switching on both lamps 10.

Lamps 10 can be switched off, other than by control pushbutton 112, also by reset pushbutton 8. Actually if at least one of lamps 10 is on and, consequently, corresponding power contacts 114,116 are closed, reset pushbutton 8 actuation defines a current path between first and second

lines 2,3 through same reset pushbutton 8, coil 25 of stepped relay 110, power contact 114,116 which are closed at that moment and the coupling diodes 122,124 in series with it. In this way, coil 25 of stepped relay 110 is energized and rotates toothed wheel 132 by one triggering trip and, consequently, shifts the operational status of power contacts 11, 116.

On the basis of the above-described stepped relay 110 sequence, it is immediately proved that, in any operational status of power contacts 114,116, both lamps 10 can be switched off by at most three actuation operations by reset pushbutton 8.

Actually, if first power contact 114 is closed and second power contact 116 is open, both power contacts 114, 116 are opened by one actuation operation by reset pushbutton 8; if first power contact 114 is open and second power contact 116 is closed, both power contacts 114,116 are opened by two actuation operations by reset pushbutton 8 ; while, if both power contacts 114,116 are closed, both power contacts 114,116 are opened by three actuation operations by reset pushbutton 8.

Once both power contacts 114,116 are opened, on any successive reset pushbutton 8 actuation (not preceded, of course, by control pushbutton 112), no current path is defined between first and second lines 2,3 through coil 25 of stepped relay 110. This prevents the same coil 25 from

being energized by reset pushbutton 8 and therefore lamps 10 from being switched on by this pushbutton.

The above described reset function is made possible by existing coupling diodes 122,124 and power contacts 114, 116, connected as above described.

Actually each power contact 114,116 defines a storage means of the on/off operational status of a corresponding lamp 10, while coupling diodes 122,124 define a logic OR gate which causes control device 12c to work in a different way according to the operational status of power contacts 114,116.

In particular, a closed power contact 114,116 indicates corresponding lamp 10 on status, while an open power contact 114,116 indicates corresponding lamp 10 off status.

A logic OR gate allows energizing of coil 25 of stepped relay 110 by reset pushbutton 8 only if one of power contacts 114,116 is closed, thereby obtaining the lamp 10 switching off sequence by same reset pushbutton 8, while preventing coil 25 of stepped relay 110 from being energized by reset pushbutton 8 only if both power contacts 114,116 are open.

In this way, sequential switching on of lamps 10 cannot be actuated by reset pushbutton 8.

According to a not shown variation, electrical system lc could include, in addition to above described main reset

pushbutton 8 allowing all lamps 10 in the house to be switched off, also local reset pushbuttons, each connected to a respective control device set 12c as above described for electrical system la. In particular, between each reset pin of each control device 12c, including first pin 100, and first terminal 118 of respective coil 25, a corresponding rectifying diode should be arranged. l Numerous modifications and variations can be made to the above described electrical system lc and control device 12c without departing from the scope of the present invention.

For instance, coupling diodes 122,124 and re- circulation diode 130 could also be inverted as regards the above description. In this case coil 25 of stepped relay 110 would be energized during the negative half-wave of supply voltage.- Considerations which could be made about electrical system lc are not repeated, because they are similar to those about electrical system la as regards lines 2,3 and 4 and their potentials.

In particular, it is pointed out that when supply direct voltages are used, diode 130 could be omitted.

Furthermore, as said above, stepped relay 100 can be reset to its start status, where both contacts 114,116 are open, by at most three actuation operations by reset

pushbutton 8. So all lamps 10 are off. Therefore reset pushbutton 8 could be replaced by any other device which is capable to generate three reset pulses at each actuation thereof, on reset line 6.

It is also pointed out that this device could also be used in above described electrical systems la and lb, because, although only one reset pulse would be needed in control devices 12a and 12b to actuate the switching off of all lamps 10, nevertheless provision of two more reset pulses would not cause, as said above, any shift in their operational status. Therefore a reset of any control device can be actuated by only one device that generates three reset pulses.

Figure 5 shows an electrical system using control devices according to a fourth embodiment of the present invention, where parts that are identical to those of the electrical systems according to previous embodiments are identified by the same reference numerals.

According to what is shown in this figure, the electrical system, which is designed, as a whole, with ld, includes, in addition to the above-described lines 2,3,4,5 and 6 for electrical system lb, a plurality of lamps 10 and corresponding control devices, these devices being implemented according to a third embodiment of the present invention and collectively designed with 12d (only two of them being shown in Figure 1), which are connected to lines

2,3,4,5 and 6 and located in the various rooms in the house.

Each control device 12d has a first pin 140 connected to first line 2 through a stepped pushbutton 62; a second pin 144 connected to reset line 6; third and fourth pins 146,148 connected to third line 4; a fifth pin| 150 connected to second line 3 and sixth and seventh pins 152,154 connected to fourth line 5 through corresponding lamps 10.

Each control device 12d includes a stepped relay 156, provided with a control pushbutton 158; first and second power contacts 160,162 ; an auxiliary contact 164; and a coil 25 (schematically shown), having a first terminal 166, connected to a first pin 140 through a first rectifying diode 168 and to a second pin 144 through its own auxiliary contact 164 and through a second rectifying diode 170, and a second terminal 172, connected to fifth pin 150.

First power contact 160 is connected between third and sixth pins 146,152, while second power contact 162 is connected between fourth and seventh pins 148,154.

In particular, first rectifying diode 168 has an anode terminal 168a connected to first pin 140 and a cathode terminal 168b connected to first terminal 166 of coil 25, while second rectifying diode 170 has an anode terminal 170a connected to second pin 144 and a cathode terminal 170b connected to first terminal 166 of coil 25 through auxiliary

contact 164.

First and second rectifying diode 168,170 also define respective half-wave rectifiers used to allow the energizing of coil 25 of same stepped relay 156 only during a first supply voltage half-wave, in particular, during the positive half-wave.

Similarly to what described for control device 12b shown in Figure 3, first and second rectifying diodes 168,170 of each control device 12d are also used to prevent corresponding stepped relay 156. from improper switching when stepped pushbuttons 62 of other control devices 12d are actuated.

Each control device 12d also includes a re-circulation diode 174, arranged between first and second terminals 166, 172 of coil 25 and having, in particular, an anode terminal 174a connected to second terminal 172, and a cathode terminal 174b connected to first terminal 166, whose use is to avoid switching problems to stepped relay 156 during second supply voltage half-wave, in particular, during the negative half- wave.

Stepped relay 156 is structurally similar to stepped relay 20. The only difference is that it has a toothed wheel, schematically shown here with a dashed line and designed with 176, which trips whenever either coil 25 is run through by an electric current or control pushbutton 158 is pressed and

performs the following actuation sequence of power contacts 160,162 and auxiliary contact 164: first and second power contacts 160,162 and auxiliary contact 164 open; first and second power contacts 160,162 and auxiliary contact 164 closed; first power contact 160 open, second power contact 162 closed and auxiliary contact 164 closed; first power contact 160 closed, second power contact 162 open and auxiliary contact 164 closed; and first and second power contacts 160,162 and auxiliary contact 164 open.

Electrical system ld operation will be described now with reference to control of only one of the lamps 10.

If we consider an initial condition where power and auxiliary contacts 160,162,164 are open and consequently lamps 10 are off, on controlling stepped pushbutton 62, a current path is defined between first and second lines 2,3 through same stepped pushbutton 62, first rectifying diode 168 and coil 25 of stepped relay 156, so causing energizing of the same coil 25 and consequent rotation of toothed wheel 176 controlling power contacts 160,162 and auxiliary contact 164 to close and consequently switching on of lamps 10.

A similar result can be achieved by controlling control pushbutton 158, which makes toothed wheel 176 mechanically

trip.

By controlling stepped pushbutton 62 or control pushbutton 158 again, toothed wheel 176 trips again and controls first power contact 160 to open, consequently switching off lamp 10, connected thereto.

By controlling stepped pushbutton 62 or control pushbutton 158 one more time, toothed wheel 176 again trips and controls first power contact 160 to close and consequently switching on of lamp 10, connected thereto, and second power contact 162 to open and consequently switching off lamp 10, connected thereto.

By controlling stepped pushbutton 62 or control pushbutton 158 again, toothed wheel 176 trips again and controls both power contacts 160,162 and consequently switching off both lamps 10.

By controlling stepped pushbutton 62 or control pushbutton 158 once more, the sequence of operations restarts from the beginning with both lamps 10 on.

Lamps 10 can be switched off, other than by control pushbutton 158, also by reset pushbutton 8. This is because, when at least one of lamps 10 is on and consequently, on the basis of the sequence provided by stepped relay 156 above described, at least one of power contacts 160,162 is closed, as well as auxiliary contact 164, then reset pushbutton 8

actuation defines a current path between first and second lines 2,3 through same reset pushbutton 8, rectifying diode 170, auxiliary contact 164 and coil 25 of stepped relay 156 and, in this way, the coil 25 itself is energized and rotates toothed wheel 176 by one triggering trip, consequently shifting power contact 160,162 operational status.

On the basis of the sequence provided by stepped relay 156, it is immediately proved that, in any operational status of power contacts 160,162, lamps 10 can both be switched off by at most three actuation operations by reset pushbutton 8.

This is because, if first power contact 160 is closed and second power contact 162 is open, both power contacts 160,162 are opened by one actuation operation by reset pushbutton 8 ; if first power contact 160 is open and second power contact 162 is closed, both power contacts 160,162 are opened by two actuation operations by reset pushbutton 8; while, if both power contacts 160,162 are closed, both power contacts 160,162 are opened by three actuation operations by reset pushbutton 8.

Once both power contacts 160,162 are opened, on any successive reset pushbutton 8 actuation (not preceded, of course, by control pushbutton 158 actuation), no current path is defined between first and second lines 2,3 through coil 25 of stepped relay 156. This prevents the same coil 25 from being energized by reset pushbutton 8 and therefore lamps 10 from being switched on by this pushbutton.

In this embodiment, the above described reset function is made possible by existing auxiliary contact 164 of stepped relay 156 arranged between reset pushbutton 8 and coil 25 of the same stepped relay 156. Such auxiliary contact 164 defines a store means of the on/off operational status of lamps 10 and causes control device 12d to work in a different way according to its status.

In particular, an auxiliary closed power contact 164 indicates a status whereby at least one of lamps 10 is on, thus allowing enregizing of coil 25 of stepped relay 156 by reset pushbutton 8 and consequent lamp 10 switching off by the same reset pushbutton 8 according to sequence above described, while an open auxiliary contact 164 indicates that all lamps 10 are off. In such a way, stepped relay 156 is prevented from being energized by reset pushbutton 8. In this way, lamp 10 is in turn prevented from being switched on by same reset pushbutton 8.

Modifications and variations can be made to electrical system 1d and control device 12d, which are similar to those above described for control devices 12a-12c and related electrical systems la-lc, and which, therefore, are not described again.

In particular, it is pointed out that when supply direct voltages are used, e. g. 12 V in direct current, re- circulation diode 174 and rectifying diode 168 could be

omitted.

Furthermore, although each of electrical systems la-ld has been described and shown as only including control devices of same type (only control devices 12a in electrical system la, only control devices 12b in electrical system lb, etc.), it is pointed out that this feature was chosen just for making description easier, without limiting the scope of the present invention. From a general point of view, an electrical system, provided according to what stated in the present invention, can, and actually will typically, be realised by using a combination of above described control devices 12a-12d, and the choice of which type of control device is to be used, and, for each type, how many of them are to be used, only depends on the control functions (circuit breaker, switch, etc.) to be implemented.

Figure 6 shows an electrical system using a control device according to a fifth embodiment of the present invention, where parts that are identical to those of the electrical systems according to previous embodiments are identified by the same reference numerals.

In particular, the control device according to fifth embodiment is particularly useful in houses which already have their own working electrical system and are made of a main entrance/exit corridor and a plurality of rooms communicating therewith.

In these houses each room is usually provided with at least a first and a second interrupting means to allow the actuation of the lamps in the same room and, respectively, of the lamps in the corridor, and all second interrupting means are usually connected to the same electric current return line, which can thus be used as a reset line, as it will be described in detaillbelow.

According to what is shown in Figure 6, the electrical system, which is designed, as a whole, with le, includes, in addition to lines 2,3,4,5 and 6 above described for the other electrical systems, a control device according to fifth embodiment of the present invention and designed with 12e, suitable to actuate corresponding lamp 10, in particular the lamp located in the house main corridor; and a plurality of control devices according to the above embodiments of the present invention, one of which is shown in Figure 6, which are suitable to actuate corresponding lamps 10, in particular the lamps of the corresponding rooms in the house wherein they are located.

In particular, as an example, Figure 6 shows, in addition to control device 12e, a control device 12b according to the second embodiment of the present invention, provided with a corresponding stepped pushbutton 62, where rectifying and re-circulating diodes 82,84 and 88 are inverted as regards what shown in Figure 3, for reasons which will be clear below.

Electrical system le also includes a plurality of stepped pushbuttons 180, which are connected between first line 2 and reset line 6 through corresponding rectifying diodes 182 and located in the corridor and in the various house rooms for controlling the lamp, that is arranged in same corridor. In particular, rectifying diodes 182 have an anode terminal 182a, connected to corresponding stepped pushbutton 180, and a cathode terminal 182b, connected to reset line 6.

Electrical system le further includes rectifying diode 186 arranged in series with reset pushbutton 8. This diode, in particular, has an anode terminal 186a, which is connected to reset line 6, and a cathode terminal 186b, which is connected to reset pushbutton 8.

Control device 12e has a first and second pins 190,192 connected to reset line 6, a third pin 194 connected to third line 4, a fourth pin 196 connected to second line 3 and a fifth pin 198 connected to fourth line 5 through corresponding lamp 10.

Control device 12e includes a stepped relay 200 provided with a control pushbutton 202, a power contact 204, an auxiliary contact 206 ad a coil 25 (schematically shown), having a first terminal 208 connected to a first pin 190 through a rectifying diode 210, and a second terminal 212, connected to a diode bridge 213.

In particular, rectifying diode 210 has an anode terminal 210a, which is connected to first pin 190, and a cathode terminal 210b, which is connected to first terminal 208 of coil 25.

Stepped relay 200 is quite similar to stepped relay 70 of control device 12b and has a toothed wheel, schematically shown with a dashed line and designed with 201, which provides an actuation sequence of power contact 204 and auxiliary contact 206 that is identical to the one provided by toothed wheel 90.

Furthermore, power contact 204 of stepped relay 200 is connected between third and fifth pins 194,198 of control device 12e.

Diode bridge 213 has a first, second, third and fourth nodes respectively denoted by with 214,215,216,217. First node 214 is connected to second terminal 212 of coil 25, second node 215 is connected to second pin 192 through auxiliary contact 206 and a rectifying diode 218, third node 216 is connected to first terminal 208 of coil 25 and fourth node 217 is connected to fifth pin 196.

Diode bridge 213 includes a first diode 219 having anode and cathode terminals connected to first and second nodes 214,215 respectively ; a second diode 220 having anode and cathode terminals connected to second and third nodes 215, 216 respectively; a third diode 222 having anode and cathode

terminals connected to fourth and third nodes 217,216 respectively; and a fourth diode 224 having anode and cathode terminals connected to first and fourth nodes 214,217 respectively.

Rectifying diode 218 has an anode terminal 218a connected to auxiliary contact 206 and a cathode terminal 218b connected to second pin 192.

Control device 12e according to fifth embodiment allows switching on of lamp 10 in the corridor from same corridor and each room by stepped pushbutton 180 and control pushbutton 202.

If we consider an initial condition where power and auxiliary contacts 204,206 are open and consequently lamp 10 is off, on controlling any of stepped pushbuttons 180, a current path is defined between first and second line 2,3 through the same stepped pushbutton 180, rectifying diode 182 arranged in series with it, rectifying diode 210, coil 25 of stepped relay 200 and diode 224 of diode bridge 213, so causing energizing of same coil 25 and consequent rotation of toothed wheel 201 controlling power contact 204 and auxiliary contact 206 to close and consequently switching on of lamp 10 arranged in series with the same power contact 204.

A similar result can be achieved by controlling control pushbutton 202, which makes toothed wheel 201 mechanically trip.

By controlling control pushbutton 202 or any of stepped pushbuttons 180 again, toothed wheel 201 trips again and controls power contact 204 and auxiliary contact 206 to open, and consequently switching off lamp 10.

By controlling any of stepped pushbuttons 180 or control pushbutton 202 once more, the sequence of operations restarts from the beginning with lamp 10 switching on.

It is remarked that existing rectifying diodes 182 arranged in series with stepped pushbuttons 180, as well as rectifying diode 210 and fourth diode 224 of diode bridge 213, make corridor lamp 10 actuation through stepped pushbuttons 180 or control pushbutton 202 only occur during first supply voltage half-wave, in particular, during the positive half-wave.

Other than by control pushbutton 202 and stepped pushbuttons 180, corridor lamp 10 switching off can also be actuated by reset pushbutton 8.

In particular, as it will be clear below, corridor lamp 10 switching off only occurs during second supply voltage half-wave, in particular, during the negative half-wave.

This is because, when lamp 10 is on, and therefore power and auxiliary contacts 204,206 are closed, a current path is defined by reset pushbutton 8 actuation between first and second line 2,3 through third diode 222 of diode bridge 213,

coil 25 of stepped relay 200, first diode 219 of diode bridge 213, auxiliary contact 206, rectifying diode 218, rectifying diode 186 and the same reset pushbutton 8. In this way, coil 25 of stepped relay 200 is energized and so rotates toothed wheel 201 by one triggering trip. This wheel consequently controls auxiliary contact 206 and power contact 204 to open and therefore to switch off lamp 10.

On any successive reset pushbutton 8 actuation (not preceded, of course, by the actuation of control pushbutton 202 or any of stepped pushbuttons 180), no current path is defined between first and second line 2,3 through coil 25 of stepped relay 200. So coil 25 cannot be energized by reset a pushbotton 8 actuation.

Use of control device 12e in an already existing electrical system for the above described house type involves relatively few modifications to the electrical system itself.

This is because it is only needed to replace those interrupting means, in the various rooms in the house, which actuate the switching on and off of the lamps existing in the same rooms, by control devices 12a-12d, and that interrupting means, which controls corridor lamp (s), by control device 12e.

Pre-arranging an additional reset line in the system is not needed, because, as a reset line, the electric current return line, which is already existing in same system and to which, as said above, all interrupting means controlling

corridor lamps are connected, is used.

During first supply voltage half-wave, reset line 6 is used for controlling the corridor lamp by stepped pushbuttons 180 and control pushbutton 202, while, during second supply voltage half-wave, reset line 6 is used for switching off the lamps that are located both in the corridor and in the various rooms, by reset pushbuttons 8.

Using reset line 6 as above described implies that control device 12b jointly exploited with control device 12e has necessarily the rectifying and re-circulating diodes 82, 84 and 88 inverted as regards what shown in Figure 3, i. e. this control device 12b must only operate during second supply voltage half-wave.

This is because, should this control device 12b operate during first supply voltage half-wave, faults in the control device 12b itself should occur as, first of all, it would not be possible to perform the reset function, which, as said above, only occurs during the second half-wave, then, when auxiliary contact 76 is closed, the actuation of any of stepped pushbuttons 180 also would cause undesired energizing of coil 25 of stepped relay 70.

Similar considerations are also worth for control devices 12a, 12c and 12d, when used in combination with control devices 12e for switching on and off the lamps in the rooms of the house.

It is also remarked that if more control devices 12e are to be used, these devices would need necessarily to be connected to different reset lines 6 (i. e. to first line 2 through corresponding stepped pushbuttons 180), because otherwise the actuation of a stepped pushbutton 180 associated to a control device 12e would also cause the switching on of all the lamps that are connected to the other control devices 12e.

Modifications and variations can be made to electrical system le and control device 12e, which are similar to those above described for control devices 12a-12d and related electrical systems la-ld, and which, therefore, will not be described again.

It is then pointed out that locations of auxiliary contact 206 and rectifying diode 218 could be exchanged.

One more thing to point out is that, in diode bridge 213 in Figure 6, second diode 220 is never run through by the electric current during control device 12e operation.

Therefore, instead of using diode bridge 213, which remains anyhow the most convenient and economical solution, only three diodes 219,222 and 224, connected as above described, could be used.

The same considerations are also worth where diodes existing in control device 12e should be inverted as regards

what is described for performing the reset function during supply voltage positive half-wave.

According to a not shown further variation, stepped pushbuttons 180 could be arranged between first pin 190 of control device 12e and reset line 6 without interposing diodes 182, there between, because existing diode 210 is already performing the same function. Then, reset pushbutton 8 could be replaced by a 2-way pushbutton having a common terminal connected to reset line 6 and a first and second terminal connected to first line 2 through corresponding diodes. In particular, in the rest position, the first terminal is connected to the common terminal, while the reset pushbutton activation causes the connection between the second terminal and the common terminal. Moreover the diode associated with the first terminal has the anode terminal connected to first line 2 and the cathode terminal connected to the same first terminal, while the diode associated to the second terminal has the cathode terminal connected to line 2 and the anode terminal connected to the second terminal.

In this way, when the reset pushbutton is in its rest position, on reset line 6 a rectified voltage is present, the polarity of which is such that the current can come to stepped relay 200 only through diode 210, and not through diode 218. Therefore, when the reset pushbutton is in the rest position, step control of stepped relay 200 can be operated by controlling stepped relay 180. On the contrary, when the reset pushbutton is activated, on reset line 6 a

rectified voltage is present the polarity of which is opposite than before, and so the current can come to stepped relay 220 only through diode 210, and not through diode 218.

This allows the reset function to be performed. Therefore all lamps 10 can be switched off by controlling the reset pushbutton only once.

Figure 7 shows an electrical system using a control device according to a sixth embodiment of the present invention, which is substantially similar to electrical system le. Therefore that parts are identified by the same reference numerals.

In particular, Figure 7 shows only two control devices according to the sixth embodiment of the present invention, which are designed with 12f. These devices are substantially similar to control device 12e. Therefore identical parts are identified by the same reference numerals.

In particular, control device 12f is different from control device 12e for are the following reasons: the stepped relay, denoted by 203, also includes a second auxiliary contact 207, which is push-pull-controlled with respect to first auxiliary contact 206 ; and control device 12f also includes a set pin 209, which is connected to reset line 6 on one side and to first terminal 208 of stepped relay 203 on the other through second auxiliary contact 207 of the same stepped relay 203 itself

and a rectifying diode 211 having an anode terminal 211a connected to set pin 209 and a cathode terminal 211b connected to second auxiliary contact 207.

In particular, stepped relay 203 is different from stepped relay 200 because it includes a toothed wheel, schematically shown with a dashed line and designed with 221, which provides the actuation sequence of power and auxiliary contacts 204,206 and 207: first auxiliary contact 206 open, second auxiliary contact 207 closed and power contact 204 open; first auxiliary contact 206 closed, second auxiliary contact 207 open and power contact 204 closed; and first auxiliary contact 206 open, second auxiliary contact 207 closed and power contact 204 open.

Electric system lf, on the contrary, is different from electric system le for the following: first pin 190 of each control device 12f is not connected to reset line 6, but to first line 2 trough a corresponding stepped pushbutton 180, which has no corresponding rectifying diode 182, the latter being existing, on the contrary, in control device 12e; and a a set pushbutton 223 and a rectifying diode 225, arranged in series are connected between first line 2 and reset line 6,; in particular, rectifying diode 225 has an anode terminal 225a connected to first line 2 through set pushbutton 223 and a cathode terminal 225b connected to reset line 6.

It is also pointed out that set pin 209 of control device 12f, shown on the right in Figure 7, is on purpose not connected to reset line 6, for reasons which will be clear below.

Control device 12f operation is quite similar to control device 12e operation as regards reset function and step control function. Therefore, it will not be described again.

On the contrary control device 12f operation is different from control device 12e operation as it is possible, through set pushbutton 223, to provide electric loads 10 with a set function, i. e. switching them on when they are off and not switching them off when they are on.

This is because, when first auxiliary contact 206 and power contact 204 are open, second auxiliary contact 207 is closed. Therefore, set pushbutton 223 actuation causes current to flow between first line 2 and second line 3 through the set pushbutton 223 itself, rectifying diodes 225, 211, coil 25 of stepped relay 203 and fourth diode 224 of diode bridge 213. This causes, in turn, energizing of coil 25 and consequent lamp 10 switching on.

When, on the contrary, first auxiliary contact 206 and power contact 204 are closed, and therefore lamp 10 is on, second auxiliary contact 207 is open. So, even pressing set pushbutton 223, the above described current path is not

created and therefore lamp 10 remains on.

In other words, the difference between a stepped pushbutton 180 and a set pushbutton 223 is in that every stepped pushbutton 180 actuation causes an on/off operational status shift in lamp 10, while a set pushbutton 223 actuation causes only the switching on, but not the switching off lamp 10. The switching off can be achieved either controlling one of stepped pushbuttons 180 or control pushbutton 202, or controlling reset pushbutton 8.

Set function is particularly useful, for instance, in conference rooms in order to pre-arrange a pre-defined brightness level by only switching on of a subset of lamps in the room. Set function is also useful to manage power units and uninterruptible power supplies in order to put in, for example, only those electric loads which are strictly necessary for system operation; or, replacing set pushbutton 223 by a twilight or timer circuit breaker, to control an electric load at set day time-table using reset line 6; etc.

The above described set function can obviously only be implemented on those control devices which have corresponding set pins 209 connected to reset line 6 while it cannot be implemented on the other control devices, as it occurs, for instance, with control device 12f, shown on the right in Figure 7, where above said current path is not generated just because its set pin 209 is not connected to reset line 6.

Modifications and variations can be made to electrical system If and control device 12f, which are similar to those above described for control devices 12a-12e and related electrical systems la-le, and which, therefore, are not described again..

It is only pointed out that, similarly to what described for electrical systems la-le, electrical system If too could be provided, in addition to set pushbutton 223, with more set pushbuttons 223. In this case, each control device 12f would be provided with an addition set pin for each set pushbutton it is connected to. Each set pin would be connected to cathode terminal 211b of rectifying diode 211 at one end through a corresponding rectifying diode identical to same rectifying diode 211, and to a corresponding local set line at the other end, this local set line being in turn connected to first line 2 through a corresponding set pushbutton.

In addition to more set pins, control device 12f could be provided, with more reset pins connected to corresponding local reset lines, as described above. Moreover, in devices having more set and reset pins, each of these pins could be connected, according to applications, to a first line 2 through a corresponding additional pushbutton. In this way, by pressing the additional pushbutton during a negative supply voltage half-wave, all control devices 12f having reset pins connected to this pushbutton are set, while, on the contrary, during a positive half-wave, all control

devices 12f having set pins connected to this pushbutton are set.

Figure 8 shows an electrical system using a control device according to a seventh embodiment of the present invention, where parts that are identical to those of the electrical systems complying with previous embodiments are identified by the same reference numerals.

According to what is shown in Figure 8, the electrical system, which is denoted as a whole by lg, includes, in addition to lines 2,3,4,5 and 6 above described for the electrical systems according to previous embodiments, a control device according to a seventh embodiment of the present invention, designed with 12g, suitable to actuate a corresponding lamp 10 and a plurality of control devices according to previous embodiments of the present invention, which are not shown in the Figure in order to simplify illustration.

Control device 12g has a first pin 230 connected to first line 2 through a stepped pushbutton 62, a second pin 232 connected to first line 2, a third pin 234 connected to reset line 6, a fourth pin 236 connected to third line 4, a fifth pin 238 connected to second line 3 and a sixth pin 240 connected to fourth line 5 through respective lamp 10.

Control device 12g includes a first stepped relay 242 provided with a control pushbutton 244, an auxiliary contact

246, a power contact 248 and a coil 25 (schematically shown), having a first terminal 250 connected to a first pin 230 and a second terminal 252 connected to fifth pin 238.

First terminal 250 of coil. 25 is then connected to second pin 232 through its own auxiliary contact 246 and an auxiliary contact 254, arranged in series with auxiliary contact 246, of a monostable relay 256, i. e. a relay type where its own auxiliary contact 254 returns to open status at the time in which electric current flow in coil 257 (also schematically shown), of the monostable relay 256 itself, is shut down. In particular, coil 257 of monostable relay 256 has a first terminal 258 connected to third pin 234 and a second terminal 260 connected to fifth pin 238.

Power contact 248 of stepped relay 242 is on the contrary connected between fourth and sixth pins 236,240.

First stepped relay 242 is quite similar to stepped relay 70 of control device 12b and has a toothed wheel 241 providing an actuation sequence of power contact 248 and auxiliary contact 246 which is identical to the one provided by toothed wheel 90.

Control device 12g operation is substantially similar to control device 12b operation, and will not be described again, as regards lamp 10 switching on and off through control pushbutton 244 and stepped pushbutton 62, while it is different from it as for the reset function, which is carried

out by using second relay 256.

This is because, when lamp 10 is on, and therefore power and auxiliary contacts 248,246 are closed, on controlling reset pushbutton 8, a first current path is defined between first and second line 2,3 through same reset pushbutton 8 and coil 257 of monostable relay 256, which is energized, and thus closes auxiliary contact 254.

The auxiliary contact 254 closing defines, in turn, a second current path between first and second lines 2,3 through auxiliary contact 246 of stepped relay 242, auxiliary contact 254 of monostable relay 256 and coil 25 of stepped relay 242, which is energized and rotates, by one triggering trip, toothed wheel 241, which in turn controls auxiliary contact 246 and power contact 248 to open, and therefore lamp 10 switching off.

On reset pushbutton 8 releasing, no more current flow exists through monostable relay 256, which consequently drops out, in this way causing its own auxiliary contact 254 to open.

On any successive reset pushbutton 8 actuation (not preceded, of course, by the actuation of control pushbutton 244 or stepped pushbutton 62), no current path is defined between first and second lines 2,3 through coil 25 of stepped relay 242, as auxiliary contact 246 of the latter is open.

Auxiliary contact 254 of monostable relay 256 performs the same function as rectifying diode 84 in control device 12b. This function, which will not be described again, allows stepped relay 242 and monostable, relay 256 operation with both supply voltage half-waves in place of a single half-wave asin control device 12b. Then, the use of auxiliary contact 254 in place of rectifying diode 84 does not require rectifying diode 82 and re-circulating diode 88 any longer.

It should be noted that, in control device 12g, second pin 232 could be connected, instead of the first line 2, to reset line 6 without affecting same control device 12f operation at all.

Modifications and variations can be made to electrical system 1g and control device 12g, which are similar to those described above for control devices 12a-12f and related electrical systems la-lf, and which, therefore, are not described again.

Figure 9 shows an electrical system which is designed, as a whole, with lh and is substantially similar to electrical system lg. Therefore, identical parts are identified by the same reference numerals. This electrical system 1h uses a control device, designed with 12h, according to an eightth embodiment of the present invention. This device is substantially similar to control device 12g, therefore, identical parts thereof are identified by the same

reference numerals. Control device 12h is different from control device 12g simply in that the function which was there performed by monostable relay 256 is here performed by a photocoupler.

In particular, the photocoupler, designed with 262, includes a photoemitting device made of a light emitting diode (LED) 264 having an anode terminal connected to third pin 234 and a cathode terminal connected to a fifth pin 238; and a photoreceiving device made of a triac 270 having a first terminal connected to second pin 232 through auxiliary contact 246 of first stepped relay 242 and a second terminal connected to first terminal 250 of coil 25.

In more detail, triac 270 is adapted to receive, and be driven from, the light which is emitted by light emitting diode 264 and in particular, it behaves like a short circuit when it is hit by the light which is emitted by light emitting diode 264 and like an open circuit when it receives no light.

Control device 12h also includes a first bias diode 266 and a bias resistor 268 which are connected between the anode terminal of light emitting diode 264 and third pin 234, and a second bias diode 272 and a bias capacitor 274 arranged in parallel between each other which are connected between the anode terminal and the cathode terminal of light emitting diode 264.

First and second bias diodes 266,272, bias resistor 268 and bias capacitor 274 are used to bias light emitting diode 264 in a per se known way, which, therefore, is not described in detail.

In particular, first bias diode 266 has an anode terminal connected to third pin 234 and a cathode terminal connected to light emitting diode 264 anode through resistor 268, while second bias diode 272 has an anode terminal and a cathode terminal connected to the cathode terminal and to the anode terminal of light emitting diode 264 respectively.

Control device 12h operation is substantially similar to control device 12g operation and is different from it in that on controlling reset pushbutton 8, a first current path is defined between first and second lines 2,3 through light emitting diode 264, which consequently emits light, so causing triac 270 to switch off.

Triac 270 switching on of thus defines a second current path between first and second lines 2,3 through coil 25 of stepped relay 242, which coil is energized and rotates, by one triggering trip, toothed wheel 241 which in turn controls auxiliary contact 246 and power contact 248 to open, and therefore lamp 10 switching off.

When examining the characteristics of the control devices and electric systems provided according to the present invention, advantages deriving therefrom are

apparent.

In particular, it is pointed out that the present invention allows the implementation of a reset function for electric loads in a simple and. economical way. This is because control devices according to the present invention use simple ellectronic components, such as stepped relays and diodes, with extremely low cost and very high commercial availability.

Moreover,, it is also useful to point out that control devices according to the present invention integrate, in only one component, the functions of both a stepped relay and a set/reset relay, so providing a step/reset device.

The manufacturing cost of a control device according to the-present invention would greatly increase where step/reset relays were to be used in place of stepped relays, as step/reset relay operation would require great complication of circuitry associated therewith for providing the step function.

This is because, in a stepped relay, each control pushbutton or stepped pushbutton actuation always actuates a contact status shift and, once contact opening/closing sequence was completed, this sequence restarts from the beginning on next stepped pushbutton actuation. On the contrary, in a set/reset relay, a contact status shift occurs only if first the set pushbutton is pressed and then the

reset pushbutton is pressed in sequence. By repeatedly pressing the set pushbutton, no further change occurs, apart from the initial one.

The above feature, although it is undoubtedly useful in other applications, makes the use of step/reset relays quite unadvisable in the implementation of this application, because it is obvious that, in order to use such type of relay, a dedicated additional circuitry should be designed, to be associated with the step/reset relay itself, which allows providing the step function, with consequent manufacturing cost increase.

Finally, it is clear that further modifications and variations can be made to control devices 12a, 12b, 12c, 12d and respective electrical systems la, lb, lc, 1d described and shown here, in addition to those which have been already described, without departing from the scope of the present invention.

For instance, the actuation sequences of the power and auxiliary contacts of stepped relays could be different from those described above.

Moreover, electric systems could include more reset pushbuttons connected between each other in parallel between first line 2 and reset line 6, and arranged in more locations in the house, e. g., for houses with more exits, arranged at the same exits.

Moreover, it is pointed out once more that, in order to provide an electrical system according to the teachings of the present invention, control devices 12a, 12b, 12c, 12d, 12f, 12g and 12h, as well as control device 12e with the above described adjustments, can be used in mutual combination, and that the choice of which type of control devices is to be used, and, for each type, how many of them are to be used, only depends on the control functions to be implemented.