SWITCH MEANS INCORPORATING SLAVE RELAYS

Abstract: A standard incandescent light circuit comprises a fixed wire from the active (10) side of an alternating current source to a light control switch located conveniently on a wall, which is connected to the switched active side of the light by another fixed wire from the wall mounted switch to the light the circuit being completed when the light is connected to the neutral side of the alternating current source. The invention replaces the light control switch with at least two master switches (51, 52) and in one embodiment by means of selectively conducting at least one of the polarities of the alternating current source the master switches selectively controls at least two loads. In one embodiment diodes (D5, D6) are used to selectively pass the positive or negative voltage half cycles of the alternating current source, and a control circuit (20) detects which master switch has changed state and via slave relay means switches (RY1-1, RY2-1) at least one of the loads independent of the other.

Description: Switch means incorporating slave relays FIELD OF THE INVENTION This invention relates to novel switch means for replacing an existing single two wire switch located between the active and switched active of a load such that a plurality of switches at the same location as the two wire switch can operate a plurality of corresponding loads while use is made without replacement of the switched active wire. BACKGROUND OF THE INVENTION It is common practice to locate light switches in rooms that are at locations convenient for the user of the light, such as on walls and more particularly near doorways. The wiring required comprises a wire means from the active side of the alternating current source to one side of the switch and a further wire means between the switch and the light commonly referred to as the switched active wire. Additional wire means is provided between the light and neutral side of the alternating current source thus completing a circuit when the switch is closed and the light operated. It is not unusual for additional electrical equipment to be added to rooms and this immediately creates the problem of how the wiring for the controlling switch of this additional electrical equipment can be run to a convenient location without extensive and often expensive rewiring or installation of new wiring. The installation of an exhaust fan to bathrooms is a common situation requiring this consideration. Thus, even though the ideal location for the fan switch is adjacent to the light switch, the inconvenience and expense of routing the required additional wires will often result in the task not being done. Alternatively the switch is located via exposed wire conduit to to rt P rt Φ rt o rt V Φ h Φ " • o o 3 rt H o H rt 3" Φ H o P P< In a preferred embodiment, the invention comprises a switch circuit to control a load in an alternating current circuit comprising, at least one master switch,' a first diode in series with said master switch to pass a first polarity of the alternating current and restrict the passage of the opposite polarity current, at least one slave switch circuit, conductor means connecting the first diode to the slave switch circuit, the slave switch circuit comprising, a second diode in series with the first diode to also pass the first polarity of alternating current, a relay circuit comprising, a relay switch to control said load, a reactance circuit means which is in series with the second diode, whereby upon said reactance circuit means being energised by the first polarity of alternating current the relay switch is operable to change state, said reactance being of sufficient magnitude to retain said energization and maintain said relay switch changed state during periods of opposite polarity current. BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of the invention is described hereunder and shown in the following figures, such that: Fig. 1 shows a circuit of the normal light switch; Fig. 2 shows a circuit of the novel switch configuration; Fig. 2A shows a circuit of the novel switch configuration adapted to control a 'TWO WAY' switch configuration; Fig. 3 shows a circuit of the novel switch configuration separately controlling two common loads; Fig. 4 shows a further embodiment of the novel switch configuration; Fig. 5 shows the use of an alternative method of passive switch elements to implement multiple switch control of loads; and Fig. 6 shows a solid state equivalent of the Fig. 2 embodiment of the novel switch. DETAILED DESCRIPTION OF THE INVENTION Fig. 1 shows a conventional light and switch circuit. This circuit comprises an active wire 10 providing a connection fro the alternating current mains source (not shown) to one side of a standard single pole light switch 11 located in a wall 14. A wire 12, the switched active, connects the opposite side of the switch 11 to the switched active side of a load located in the ceiling 15. In this example the load is an incandescent light 13. The opposite side of the load is connected to the neutral side of the alternating current mains (not shown) thus completing a circuit when switch 11 is closed and mains power supplied to the light 13. Any changes to the requirements of the room serviced by this conventional light and switch circuit such as the installation of another light which has its own switch, has necessitated the fitting of at least a switched active wire for the new load. The expense of installation and the disturbance caused is great, consequently the job is not done or wires are routed vi exposed conduit so that the required circuit can be provided. Alternatively, the independent operation of the extra load is compromised and the old and new loads commonly a fan and light are connected in parallel thereby to operate together when the existing switch is used. These problems are overcome by the invention as is shown in th following embodiment which uses the existing active 10 and switched active 12 wires without disturbance. Changes are onl required at the readily accessible wall switch 11 location and at a convenient termination location of the switched active wire 12 generally in the ceiling 15. Fig. 2 shows circuit embodiment of the novel switch configuration comprising of an active wire 10, connected from the alternating current mains source (not shown) to the location previously occupied by a single pole light switch 11 as in Fig. 1. Wire 10 is connected to two single pole master switches SI and S2 which are located on the wall in place of the single light switch 11. This portion of the embodiment is referred to as the master switch circuit. To switch the ACTIVE supply 'ON' at LOAD 1, switch SI is moved from non-conduction to conduction (i.e. closed). During the period switch SI is closed and the potential of the active side of the switch is positive with respect to neutral i.e. during positive half cycles of the alternating current supply, a first diode D5 conducts and a half wave rectified signal is applied via wire means 12 to the control input of circuit means 20 located in the ceiling or other convenient place. This portion of the embodiment is referred to as the slave circuit since it is controlled by the master switch circuit. The positive half cycle current conducts via D5, wire 12 and a second diode Dl to the coil RYl of a suitably rated mains voltage slave relay and on to the neutral side of the supply. Energization of the slave relay coil causes the relay contact RYl-1 to change state by moving from its normally closed position NC-1 to its open position 0-1 thus allowing conduction of power from the active side of the load to the neutral side via the relay contact and LOAD 1. As is apparent from the description, LOAD 1 is connected between contact 0-1 and the common neutral during energization of the relay coil. Alternatively the switching of SI from open to closed will disconnect the conduction of power to LOAD 1 by changing the state of the slave relay contact and thereby disconnect the conduction of power to LOAD 1. A relay circuit comprising a relay coil and a corresponding contact is but one embodiment of a reactance element and its corresponding load control means. The reactance which may be a capacitive or inductive element is primarily an energy storage device. During negative half cycles of the alternating current, D5 is non-conducting but current that was established in slave relay coil RYl continues to flow through resistor Rl and diode D3 due to the back e.m.f. (electromotive force) of the coil. This current decays exponentially through ohmic loss but with a time constant long enough to keep the relay contact RYl-1 in its open position until the next positive half cycle is conducted from SI via D5 and Dl. The current decay rate is proportional to the total resistance in the current loop, formed by D3, Rl and the impedance of RYl. Therefore, the total resistance is ideally very small to ensure a long delay, however, Rl is required to limit currents caused by transient mains over voltages and protect the diodes D3 and similarly D4. The actual decay rate selected is required to balance each of these two requirements to ensure that both are satisfied. Switch circuit S2 operates in exactly the same manner as described above. When switch S2 is closed, negative half cycles are applied via diode D6 to RY2 via diode D2, closing RY2-1 contact and supplying ACTIVE to LOAD 2. As described previously, R2 and RY2 set the decay rate of the inductive current in RY2 such that the RY2-1 contact is kept open during positive half cycles and until the incidence of the next negative half cycle. As will be apparent to those skilled in the art more than two loads can be controlled by this method of relay control. The simplest expansion being implemented by increasing the number of poles of the two relays thereby ganging loads requiring the same control via a single switch. Different types of loads could also be controlled by using .the relays. For example, a load may be remotely controlled via additional control circuitry which is designed for example to drive optically isolated loads or loads powered by different power sources. Also the load may be itself another switch contact which itself controls a load. The term load is to be read as including a switching means and is illustrated in Fig. 2A. In another embodiment, not shown, control of various loads could be implemented by using control means which recognises the rising and falling voltage portions of both the positive and negative half cycles of the alternating current provided by 51 and S2 and thereby be providing a means of signalling to a minimum of four different loads. This of course may require more complexity in the design of SI and S2 but would still allow the utilisation of existing active and switched wires 10 and 12. A further embodiment shown in Fig. 2A shows the novel switch circuit configured to allow the use of a single pole change¬ over circuit commonly referred to as a two-way circuit. This type of circuit is used to allow dual switch control of a single load, commonly a light, from two different switch locations. The novel switch therefore enables an existing single switch and load arrangement to be converted into a 'two- way' switch and load. Fig. 2A shows two configurations for wiring of the additional switch of the two-way switch circuit. As will be apparent switches SI' and S2' could themselves be relay poles of a novel switch circuit. Fig. 3 shows a typical application of the invention where switch SI when closed, switches the LOAD 1 light 30 'on' while switch S2 is open keeping LOAD 2 the fan 31 'off . Alternatively, the opposite mode can be implemented by closing 52 and opening SI. Of course, closing or opening both switches will switch 'on' and 'off both loads respectively, thereby providing totally independent operation of the two loads from a modified double switch plate 32 and utilising the existing ACTIVE wire 10 and SWITCHED ACTIVE wire 12 to control an existing load 30 and a new load 31. This simple and effective circuit negates any expensive and inconvenient additional wire runs . Fig. 4 shows a further embodiment of one aspect of the invention wherein a plurality of switches Sl-Sn and corresponding resistors Rl-Rn are arranged to pass a variety of potential values. This switch bank replaces the single pole light switch 11 shown in Fig. 1 and comprises an arrangement of simple passive components. Prior art switch signalling means are known to comprise active components which not only detect switch operation but actively send and communicate the states of the switches to a remotely located control circuit, however, this is complicated, expensive and generally requires installation of wires other than those existing. Commonly more than one wire is required for such prior systems or alternatively very complicated transmission and reception circuits are implemented to transfer the required information over a single wire. The essence of the embodiment shown in Fig. 4 is that the switches Sl-Sn and resistors Rl-Rn are passive electronic elements, that is, they modify but do not add any voltage or current to the circuit, and the control means interprets which switch or switches are operating and thereby controls respective loads 1 - n. Existing wires ACTIVE 10 from the ACTIVE side of the supply and SWITCHED ACTIVE 42 to the load control circuit 41 are still used while wire 43 from the ACTIVE side is added by junctioning the existing wire or running a separate wire to supply the path for power to the LOADS 1 - n and their NEUTRAL connections made via wires 45., 45, 45 respectively. Wire 46 represents the NEUTRAL connection for the control circuit 41. Fig. 5 shows a further embodiment of the use of the switch concept shown in Fig. 4 which comprises the use of a plurality of standard switches combined with passive resistance components whereby the detection of the state of switch status and change is deduced by a comparator located at the termination of the existing and undisturbed switched active wire which previously was only used to control one load with one switch. As an example the resistors R, 2R, 4R...2(n-l)R represent unit value R and 2xR and 4xR respectively, and are shown adjacent to switches SI to Sn respectively. This arrangement provides a unique current flow in the circuit for every possible combination of switches opened and closed. The comparator block SI determines which current is flowing at any one time and communicates that information to the decoder S2. The decoder block then mimics the state of the switches Sl-Sn and activates the control of corresponding normally open or normally closed contacts which thereby may operate various loads. An alternative arrangement to the resistor network shown would be the use of capacitors wherein the comparator would adduce the unique voltages, current or phase angles of current present o the second of the two existing wires. Fig. 6 shows a solid state embodiment of the novel switch as described and shown previously in Fig. 2 wherein with the closure of master switch SI, positive voltage half cycles of the alternating current supply are conducted via diode D5, resistor R60 and diode D61 to zener diode ZD62. The breakdown voltage of the zener diode is achieved during the rising voltage portion of the half cycle and is a sufficient voltage to charge capacitor C65 and to drive light emitting diode D64 into conduction which thereby emits optical radiation. Thus optically triggered triac TR66 is operated and a conduction path is provided from ACTIVE to the SWITCHED ACTIVE side of LOAD 1. Capacitor C65 acts to delay the turn 'off of the triac TR66 during negative half cycles by supplying power to the light emitting diode D64 and thereby continues to emit optical radiation to trigger triac TR66 'on' . This circuit configuration can be seen as equivalent in operation to the embodiment described and shown in Fig. 2, however it utilises a variety of solid state devices in preference to the electromechanical relays shown previously. This invention resides in a means, that, because of the nature of electronic design could be achieved in many ways by a person skilled in the art. The essence of this invention is its simplicity and thus its consequent efficiency of manufacture and uncomplicated installation by electrical trades persons.

Claims: The claims defining the invention are as follows:- 1. A switch circuit to control a load in an alternating current circuit comprising, a master switch having a conducting and non-conducting state, at least one passive circuit component in series with said master switch to pass a portion of the alternating current signal when the master switch is in a conducting state, at least one slave circuit, conductor means connecting the first passive circuit component to the slave circuit, the slave circuit comprising, a circuit means to detect the portion of the alternating current passed by the first passive circuit component when the master switch is in a conducting state to thereby control the load. 2. A switch circuit according to claim 1 wherein the circuit means comprises comparator means, and load control means said comparator means having an input coupled to the conductor means to receive the alternating current signal and compare the signal with a predetermined signal whereby the load control means switches on the load if the signals are the same. 3. A switch circuit according to claim 1 wherein the circuit means comprises detection means, and load control means said detection means having an input coupled to the conductor means to receive the alternating current signal and detect the portion of the alternating current signal received, whereby the load control means being coupled to the detection means is responsive to the portion of the signal received and controls the supply of a proportional portion of the available power to the load. 4. A switch circuit according to claim 1 wherein said passive circuit component comprises a resistor which passes a portion of the alternating current signal wherein the circuit means comprises a comparator means responsive to detect the change in the alternating current signal and produce a voltage representative of the state of the master switch. 5. A switch circuit according to claim 1 comprising a plurality of said master switches and passive circuit components in series with said plurality of master switches to pass a portion of the alternating current signal when the master switches are in a conducting state, said slave circuit comprising, comparator means to detect the total portion of the alternating current passed by the passive circuit components when their respective master switches are in a conducting state to thereby control predetermined ones of a plurality of loads. 6. A switch circuit according to claim 5 wherein the circuit means further comprises decoder means having at least one load control circuit output signal generator and at least one load control circuit means wherein the decoder means receives the voltage produced by the voltage comparator means and produces an load control circuit output signal to indicate the conducting state of a respective master switch, wherein the. generator output signal is coupled to a load control circuit means to control a load coupled thereto. 7. A switch circuit to control a load in an alternating current circuit according to claim 1 comprising, at least one master switch, a first diode in series with said master switch to pass a first polarity of the alternating current and restrict the passage of the opposite polarity current, at least one slave switch circuit, conductor means connecting the first diode to the slave switch circuit, the slave switch circuit comprising, a second diode in series with the first diode to also pass the first polarity of alternating current, a relay circuit comprising, a relay switch to control said load, a reactance circuit means which is in series with the second diode, whereby upon said reactance circuit means being energised by the first polarity of alternating current the relay switch is operable to change state, said reactance being of sufficient magnitude to retain said energization and maintain said relay switch changed state during periods of opposite polarity current. 8. A switch circuit according to claim 7 wherein said reactance comprises, a reactance element in series with the second diode, a reactance energization delay element operable to retard the dissipation of energy from the reactance element during periods of opposite polarity current. 9. A switch circuit according to claim 8 wherein said reactance element comprises a relay coil, and said delay element comprises a diode and resistor in series with each other and which are both in parallel with the relay coil thereby acting to dissipate the back electromotive force of the energized relay coil during periods of opposite polarity current. 10. A switch circuit according to claim 9 wherein said relay switch comprises a relay contact operable upon energization of the relay coil to change state thereby controlling the supply of power to the load. 11. A switch circuit according to claim 8 wherein said reactance element comprises a capacitor, and said delay element comprises a light emitting diode in parallel with the capacitor thereby acting to dissipate the energy accumulated in the capacitor during at least a part of the period of the first polarity of alternating current, the capacitor being of sufficient capacitive value to sustain emission from the diode during the period of opposite polarity current. 12. A switch circuit according to claim 11 wherein the relay circuit further comprises a voltage regulation device located in parallel with the reactance element to limit the voltage applied to the reactance element. 13. A switch circuit according to claim 12 wherein the voltage regulator device is a zener diode. 14. A switch circuit according to claim 13 wherein said relay switch comprises an optically triggered triac operable upon reception of light from the light emitting diode to control the supply of power to the load. 15. A switch circuit to control at least a first load and second load in an alternating current circuit comprising first and second master switches, said first master switch comprising, a first diode in series with said first master switch to pass a first polarity current of the alternating current and restrict the passage of the opposite polarity current, a first slave switch circuit, conductor means connecting the first diode to the first slave switch circuit, the first slave switch circuit comprising, a second diode in series with the first diode to also pass the first polarity of alternating current, a relay circuit comprising, a relay switch to control the first load, a reactance circuit means which is in series with the second diode, whereby upon said reactance circuit means being energised by the opposite polarity of alternating current the relay switch is operable to change state, said reactance being of sufficient magnitude to retain said energization and said relay switch changed state during periods of the opposite polarity current, said second master switch comprising, a third diode in series with said second master switch to pass the opposite polarity current of the alternating current and restrict the passage of the first polarity current, a second slave switch circuit, conductor means connecting the third diode to the second slave switch circuit, the second slave switch circuit comprising, a fourth diode in series with the first diode to also pass the opposite polarity of alternating current, a relay circuit comprising, a relay switch to control the second load, a reactance which is in series with the forth diode, whereby upon said reactance being energised by the opposite polarity of alternating current the relay switch is operable to change state, said reactance being of sufficient magnitude to retain said energization and said relay switch changed state during periods of the first polarity current, whereby operation of the master switches independently controls the first and second loads. 16. A switch circuit substantially as hereinbefore claimed and described with reference to and illustrated in the accompanying figures.

Inventors: STOCK PETER MICHAEL, YOUNG ANDREW JOHN, STOCK, PETER, MICHAEL, YOUNG, ANDREW, JOHN
Applicants: STOCK PETER MICHAEL, YOUNG ANDREW JOHN, STOCK, PETER, MICHAEL, YOUNG, ANDREW, JOHN
Application year: 1990
Main classification: H05B37
IPC codes: H05B37