GB2135839A - Switch assembly with adjustable timing for use in lighting entrances and stairways - Google Patents

Abstract

Automatically timed lights 9 for entrances and stairways in a mains circuit are selectively actuated by switches (4, Figs. 1,3) fed by transformer 10 and rectifier 11 to operate at very low voltage and small current. In conditions of low natural illumination, closure of one of the switches causes integrated circuit 15 to deliver a pulse of duration determined by potentiometer 16 to an isolation device 7 containing an optical coupler and a zero passage voltage control whereby the pulse is delivered to triac 8 which switches on the lighting network while the switching assembly is isolated from the mains voltage by transformer 10 and device 7. When natural illumination is above a level set by potentiometer 27, a photoresistor 25 acting through transistor 26 inhibits the action of integrated circuit 15. <IMAGE>

Description

SPECIFICATION A static switch assembly with adjustable timing for restricted use in lighting entrances and stairways The present invention, relates to a static switch assembly with an adjustable timer for restricted use particularly in the lighting of doorways and stairways.

An object of the present invention is basically to contribute to obtaining a saving of energy by regulating the time of illumination of a lighting network for entrances, halls and similar locations. It is well known that with the conventional installations for stairways in dwellings, for example, that the turning on of the switch by the user causes the illumination of all the existing light bulbs in the stairway of the dwelling or locality, which is continued during a regulated time, normally by the action of an electromagnetic or electronic device.

That causes a waste of electrical energy which is totally unnecessary on the floors on which the user is not present. Besides due to the intrinsic peculiarities of each installation it could happen that on some floors or places where the light is installed there is enough natural illumination for the artificial lighting to be unnecessary, a situation which is not controlled by the conventional timing devices for lighting which activate the light bulbs connected to them independently of the level of natural illumination.

There is no doubt that these arrangements cause an unnecessary waste of energy, a circumstance which the present invention is designed to overcome in that apart from introducing some known characteristics into the existing devices adds some innovations which provide substantial advantages when it comes to its use in temporary lighting installations.

In carrying the invention into effect a static switch, based on a triac, which connects a lighting line during a predetermined time starting with an instantaneous pulse from any one of a network of switches installed in the area to be illuminated, has the characteristic that these switches will turn on the whole lighting network only if the level of illumination is sufficiently low, while in the case where there exists natural illumination which is adequate turning on the switches will not cause the light bulbs to turn on. Apart from this, once the device is activated and when the preset time has passed,the light is disconnected automatically.

The arrangement allows the preferred form of installation of the device to be incorporated, for example, floor by floor on a stairway or zone by zone along a hallway, in such a way that only the network of lighting associated with a respective zone when controlled by the associated device will be activated.

This avoids the unnecessary illumination of a plurality of lights, such as occurs with conventional installations. Also some of the switches, due to their characteristics of electrical isolation, which will be described below, can be incorporated into the very doors of elevators, the users' doors or similar places, so that the turning on of the lighting network can be effected automatically when one of these doors is opened.

As was indicated above and in the area in which an installed device has natural illumination, the switches for turning on the lighting will remain inactive when there is a sufficient level or natural light. This level of "sufficiency", of lighting depends on the characteristics of the location, for which the device has been designed with an adjustment for the level of illumination. This level is lower than that at which artificial lighting can begin to be used in an automa ticallytimed manner. The inhibition of the switches prevents unnecessary and voluntary lighting during the day on the one hand and allows, on the other hand, each floor to use the artificial lighting only from the time when it is really necessary, independently of the other floors of the building and according to the particular height and orientation of each one of the floors.

The time of operation is obviously regulatable and for its use in stairways a margin of timing between 0.5 and 3 minutes has been selected. The error of the preadjusted time will never be more than 3%.

Once the user has activated a switch to cause a lighting network to be turned on successive actuations of the switches will not prolong the time of the preadjusted lighting. That is, a device adjusted for 40 seconds duration will disconnect the lighting 40 seconds after the switch is activated the first time, independently of the fact that during those 40 seconds any switch may have been actuated again.

Besides the characteristic of saving energy an important detail which the device offers needs to be pointed out. That is that its use with flourescent lights increases considerably the useful life of the tubes, because the device is incorporated in a circuit which only allows the lighting to be connected when the alternating current of the electrical network passes zero, breaking the circuit around + or - 15 volts outside said level. In this way the filament of a tube which has aged due to many hours of operation can better resist the transitory effects at the moment of connection, thereby reducing the risk of breaking the filament. Therefore, among the most relevant characteristics which the invention offers can be summarized in the following points: 1.A saving of energy due to the possibility of restricting the use of the lighting installation only to floors or zones where it is necessary.

2. A reduction of the cost of replacing lighting tubes, due to giving them a longer useful life.

3. A great precision in the time selected for operation.

4. An absence of moveable parts, such as the electromechanical relays used in conventional timing devices since the devices made according to the invention are totally electronic.

5. A great security for the user since the switch circuit remains isolated from the electrical network and is associated with a direct current network of very low voltage.

In order that the invention may be clearly understood and readily carried into effect apparatus in accordance therewith will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of an electrical circuit, Figure 2 is an electrical circuit diagram, and Figure 3 is a diagram indicating a way in which the apparatus can be installed in practice.

Referring to the figures and especially the block diagram shown in Figure 1, a static switch with an adjustable timer and designed for use restricted to the lighting of entrances and stairways is fed from supply (1) which transforms an alternating current of a network of 220 V. or 125 V. to a direct current with low voltage which is filtered and stabilized. The source (1 ) supplies the rest of the units represented by the blocks in Figure 1.

Among these blocks the one marked (2) represents a timing circuit, mounted as a monostable multivibrator, whose typical period is determined by a time constant determined by a device represented by block (3) formed by a minimum of passive components. The timer is controlled in its action by a network (4) containing switches distributed along the lighting network, but also this timer (2) is subjected to authorization imposed by block (5) which through a photoresistance (6) permanently measures the level of natural illumination which exists in the installation.

The timing block (2), when it is activated, influences a block (7) in which means for electric isolation are incorporated, as well as a control circuit for zero voltage passage in the network. Block (7) controls the action of block (8), made up basically of a bi-directional solid state circuit breaker, more commonly called a triac, by means of which the interruption or passage of the current toward light bulbs (9) in the installation is carried out.

In greater detail these blocks are represented in the circuit shown in Figure 2, in which block (1) or the supply source is formed by a transformer marked (10) which has condensor (11 a) incorporated in its primary circuit planned as an anti-interference element against possible disturbances which could be introduced into the rest of the circuit from the electrical network.

The subsidiary of this transformer (10) acts on a rectifying stage (11), formed either by silicon diodes or by an integrated rectifier, whose output is connected to a filter condensor (12), set previously as a stabilizing stage for current delivered by a zener diode (13) and a discharge resistance (14). This circuit, as can be observed in Figure 2 supplies the current to the rest of the integral components of the device.

The timing block (2) is formed basically by an integrated circuit (15), associated with a network of passive components and capable of generating an active pulse whose period is determined by the values of the components which make up block (3) for the timing regulation. These components, integrated in the block marked (3) are a potentiometer or adjustable resistance (16), a resistance (17) and a condensor marked (18). By providing the variable resistance (16), since the timed period is a function of the values of the stated components, the ohmic value of the potentiometer (16) can be varied so as to make the length of the inherent period of the pulse emitted by the integrated circuit (15) vary.

The monostable circuit has a trigger intake (19) which is activated by means of the detection of a negative pulse. This negative pulse is achieved when one of the switches (4) is activated changing the state of the point marked (20) on the circuit subjected to a determined level of voltage by the presence of the resistances (21) and (22) mounted as a divider of the voltage supply. The negative pulse obtained by activating the switches (4) is transmitted to the input (19) on the integrated circuit (15), through resistance (23).

Besides, the integrated or monostable circuit (15) is provided with a decoupling condensor (24) and is subjected to the control block (5) which permanently measures the level of natural illumination which exists in the installation.

Block (5), as can be seen in Figure 2, is formed by a photoresistance (25) contained in a polarization circuit connected to the positive side of a transistor (26). When the illumination is at a determined level, a level which is adjusted by means of a potentiometer (27) to a level wherein illumination is by natural light, the photoresistance (25) adopts a value much lower than its nominal value, whereby a current is fed through a resistance (28) to the base of the transistor (26), causing the latter to pass from its non-conducting state to its conduction state. The output of the integrated circuit (15) is thereby blocked by current which has access through the collector emitter junction of the transistor to the positive supply pole through resistance (29).

Nevertheless, when the level of natural illumination is insufficient the photoresistance (25) will adopt a higher ohmic value so that the transistor (26) passes to the non-conducting state and allows the normal operation of the monostable or integrated circuit (15). As was said previously the variation of the transistor (26) is goverened by the potentiometer or adjustable resistance (27).

Under normal conditions of operation, that is, once the user has actuated one of the switches (4) and when the photoresistance (25) does not detect a sufficient level of natural illumination, the integrated circuit (15) will send a pulse of strength equal to that of the supply voltage for the period determined by the time constant defined by the resistances (16 and 17) and by the condensor (18). The pulse is received by block (7) through resistance (30).

This block (7) is formed by an integral optical coupler,that is, a capsule which contains an eletroluminiscent diode associated with a phototransistor, in such a way that the illumination of the electroluminiscent diode will make the phototransistor embedded in the capsule conduct activating a gate (31) of the triac (8) which, as is known is a two directional switch controlled electrically.

Block (7) presents, besides, the interesting peculiarity that the opening of the gate (31) ofthetriac (8) is not done at random but that it is done preceiseiy when the alternating current passes the threshold of zero voltage. This is obtained with the presence of a circuit detector of zero passage of voltage which, advantageously, is integrated in the block (7) itself.

The pulse for the command of the triac (8) is received by its gate (31) through a resistance (32). A series RC network is provided between the active terminals of the triac (8) to protect this circuit breaking element (8).

Therefore, the light bulbs (9) of the lighting network will always shine when the gate (31) of the triac (8) receives the pulses that block (7) sends since an electrical network including a voltage supply (34) will be connected between its terminals, since the triac (8) reacts in such a situation like a closed switch.

Once the inherent time of the period of the pulse emitted by the integrated circuit (15) has passed, the gate of the triac (8) will stop being supplied, so that this will behave like an open switch, turning offthe lights (9) of the lighting installation.

It is necessary to say that the space occupied by the apparatus described is a minimum one and its installation is very simple, as the diagram of Figure 3 shows. A box (35) having small dimensions houses the different circuits and allows the control or regulation of the adjusting elements, such as the potentiometer (16) which regulates the timing and the potentiometer (27) which regulates the level of sufficiency of the natural illumination.

In a window (36) the photoresistance (25) is located to detect the level of luminosity, while the different connections necessary for the installation can be fixed along a strip (37), such as the light bulb network (9), the voltage supply (34) and the switch line (4), as well as a protection fuse (38).

All this structure offers some great advantages with respect to the different existing devices which are intended to carry out some of the functions which the device according to the invention performs.

In the first place, the known devices work either mechanically or electromechanically and even electronically but, in no case, do they offer the peculiarities and advantages described above.

A considerable improvement stems from the fact that the permanent insulation which exists between the 220 volt supply network for the lighting system and the control device, converts the installation into two independent circuits, that is, without any existing contact between one circuit and the other, allowing the use of switches or sensors with a low level of electrical insulation.

This insulation is provided on one hand by the transformer (10) which usually has a minimum proof voltage, between primary and secondary, of approximately 6,000 volts, while on the other hand the insulation which is offered by the integrated circuit outlet optical coupler (5) has a minimal insulation situated around 7,500 volts.

A substantial advantage is due to the fact the installation of switches does not need to comply with the severe insulation regulations nor those for breaking capacity, since the level which is present in its terminals is inferior to 9 volts and the current which can circulate through them is in the order of 12 milliamperes. In the case of error or breakdown one of these poles could be grounded without causing undesirable effects either in the device or in the electrical supply network itself.

Another advantageous characteristic which the invention offers as compared to the known forms of apparatus is its static switch character which is totally silent and does not need any kind of maintenance, a characteristic which is not found in the timers with moveable plates whose contacts need a certain maintenance due to the deterioration which they suffer because of the continuous turning on and off.

Besides, the incorporation in the device itself of the photo resistance (25) which controls the level of natural illumination that can be accommodated provides important savings in the costs which affect the user, being relative to the amount of energy used.

Lastly, it must be noted also that although throughout this descriptive statement the device has been described as appliable to the lighting of stairways, entrances and similar locations, this circumstance is no obstacle to its being applied to any interior space or exterior one whose lighting must be limited to certain hours and which needs noncontinuous or temporary use.

Having described sufficiently the nature of the invention and its practical operation, it is necessary expressly to state that such variations which engineering and practice counsel as to the use of materials and manner of manufacture can be adopted without altering the essential usefulness of the claimed invention.

Claims (5)

1. A static switch assembly with adjustable timing for restricted use in lighting entrances and stairways, which allows a timed turning on of a network of lights connected to the assembly, depending on the existing level of natural illumination in the zone of installation of the lights, the assembly being made up of an electronic circuit which includes a supply source in which alternating current is converted to stabilized direct current, a timing circuit with a monostable multi-vibrator and a zero passage voltage control for the network of lights, with an isolation block and control command for the gate of a triac mounted as a controlled switch for the lights, the trigger circuit of the monostable multivibrator being connected to a network of switches which are distributed throughout the installation and is arranged so that the activating of the monostable multi-vibrator is subjected to the control of a circuit which measures the level of natural illumination which exists, in the vicinity of the lights, the circuit for measuring the natural illumination comprising a photoresistance connected to the positive Zone of a polarization circuit including the base of a transistor whose emitter is directly connected to the output of the monostable multi-vibrator circuit, the isolation block and the zero passage voltage control being arranged to receive the output signal from said monostable multi-vibrator circuit through an electroluminiscent diode which is opticaliy coupled to a phototransistorwhich is jointly integrated with a circuit for the zero passage voltage control and means being provided for regulating the length of time that the lights remain illuminated.

2. A static switch assembly with adjustable timing for restricted use for lighting entrances and stairways, according to Claim 1 in which the triac is connected in series with one of the poles of the alternating current network comprising the lights and has, between its terminals, an R-C protection circuit, its power circuit being controlled by means of an integrated circuit, controlled in turn by the timing circuit, which is made up of the optical coupler comprising the phototransister and electroluminescent diode with the circuit for the zero passage voltage control of the alternating current in the network.

3. A static switch assembly with adjustable timing for restricted use for lighting entrances and stairways, according to Claim 1 or Claim 2, in which the network of switches which controls the trigger stage of the monostable multi-vibrator is insulated galvanicaily from the alternating current network for lighting and carries direct current of very low voltage.

4. A static switch assembly with adjustable timing for restricted use for lighting entrances and stairways, according to any one of the preceding claims, in which the transistor associated with the photoresistance is connected as an inhibitor of the monostable multi-vibrator circuit, according to whether the transistor is acting as a conductor or non-conductor.

5. A static switch assembly with adjustable timing for restrictive use for lighting entrances and stairways substantially as hereinbefore described with reference to the acompanying drawings.