GB2378063A

GB2378063A - A system for supplying and controlling low-voltage lamps

Info

Publication number: GB2378063A
Application number: GB0211905A
Authority: GB
Inventors: Mauro Guzzini; Maurizio Senigagliesi
Original assignee: GITRONICA Srl
Current assignee: GITRONICA Srl
Priority date: 2001-05-23
Filing date: 2002-05-23
Publication date: 2003-01-29
Also published as: DE20207951U1; ITBO20010323A0; GB0211905D0; ITBO20010323A1

Abstract

A system (1) for supplying and controlling low-voltage lamps 4, and having at least one voltage transformer (2) for supplying a low voltage; a number of power circuits (3) supplied by the voltage transformer (2) and for regulating the supply voltage of the lamps (4); and a central control unit (5) for selectively controlling the power circuits (3) to regulate turn on/turn off and the brightness of each lamp (4). There may also be a remote control handset 9 for the central control unit 5.

Description

SYSTEM FOR SUPPLYING AND CONTROLLING LOW-VOLTAGE LAMPS The present invention relates to a system for supplying and controlling low-voltage lamps.

More specifically, the present invention relates to a new system for supplying and controlling low-voltage lamps, and which provides both for remote adjustment of the brightness of each lamp, and for regulating the supply voltage of the lamps to increase their average working life.

It is an object of the present invention, in fact, to provide a low-voltage-lamp lighting system, designed to implement the above functions, and which is also cheap and easy to produce.

According to the present invention, there is provided a system for supplying and controlling lowvoltage lamps, characterized by comprising: at least one voltage transformer for supplying a low voltage; a number of power circuits supplied by the voltage transformer and for regulating the supply voltage of said lamps; and

a central control unit for selectively controlling said power circuits to regulate turn on/turn off and the brightness of each said lamp.

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which: Figure 1 shows, schematically, a system for supplying and controlling low-voltage lamps in accordance with the teachings of the present invention; Figure 2 shows an electric diagram of a power circuit forming part of the Figure 1 system for supplying and controlling low-voltage lamps; Figure 3 shows an electric diagram of a number of devices forming part of the central control unit of the Figure 1 system for supplying and controlling low-voltage lamps.

Number 1 in Figure 1 indicates as a whole a system for supplying and controlling low-voltage, e. g. quartziodine, lamps, and which comprises a voltage transformer 2 for transforming a high alternating voltage (e. g. 230 V) to a low alternating voltage (e. g. 12 V); a number of power circuits 3 supplied with low voltage by transformer 2, and for supplying a given electric power to lamps 4; and a central control unit 5 for selectively controlling the electric power supplied by each power circuit 3, so as to regulate the brightness of each lamp 4.

In the example shown, voltage transformer 2 is a known type, and may preferably, though not necessarily,

be electronic or magnetic. More specifically, voltage transformer 2 is connected by the primary circuit to the supply mains 6, from which it receives a high alternating voltage, and supplies, i. e. to the terminals of the secondary circuit, a low alternating or substantially direct voltage (e. g. 12 V).

Power circuits 3 are also of known type, and are connected at the input to the terminals of the secondary circuit of transformer 2, from which they receive the low alternating voltage, and are connected at the output to lamps 4, to which they supply the electric power, i. e. the regulated current/voltage. Figure 2 shows an example of a power circuit 3.

With reference to Figure 1, central control unit 5 comprises a known microprocessor 7 (shown in detail in Figure 3) for selectively controlling power circuits 3 to regulate the brightness and turn on/turn off of each lamp 4 ; and a data communication device 8 connected to microprocessor 7 to permit two-way data exchange between microprocessor 7 and a remote-control unit 9.

Central control unit 5 also comprises a known supply circuit 10 (shown in Figure 3) for supplying both microprocessor 7 and data communication device 8. In the example shown, supply circuit 10 is connected at the input to the secondary circuit of transformer 2, from which it receives the low alternating voltage, and supplies a low direct voltage to the electronic circuits, i. e. microprocessor 7 and data communication device 8.

With reference to Figure 1, microprocessor 7 is connected to and supplies each power circuit 3 with a control signal COM containing coded information relative to the command to be imparted to lamp 4, i. e. turn on/turn off command, or brightness adjustment.

Microprocessor 7 is also connected to data communication device 8, by which it exchanges information with a data communication device 11 of remote-control unit 9.

It should be pointed out that communication between central control unit 5 and remote-control unit 9 is of known type, and may be effected, for example, by IR, RF communication.

In addition to data communication device 11, remotecontrol unit 9 also comprises a user control keyboard 12 for entering commands to turn on/turn off or adjust the brightness of each lamp 4 ; a known, e. g. liquid-crystal, display device 13 showing the commands or functions entered; and a microcontroller 14 for controlling all the functions of remote-control unit 9, i. e. transmitting to central control unit 5 and displaying on display device 13 the commands entered on control keyboard 12.

It should be pointed out that, besides turning on/turning off and/or adjusting the brightness of each lamp 4, microprocessor 7 also provides for optimizing supply of lamps 4 by appropriately controlling the main "critical"supply situations to which lamps 4 are subject, and which are mainly responsible for reducing

the average. working life of lamps 4.

More specifically, microprocessor 7 controls the following"critical"conditions : - a first critical condition produced when turning lamps 4 on ; - a second critical condition produced by sudden changes in the supply voltage of lamps 4, in turn caused by variations in mains 6 voltage or by variations in load, e. g. when one or more lamps 4 are turned on/off, or are added to or removed from system 1.

More specifically, microprocessor 7 controls the first turn-on critical condition by performing, by means of power circuits 3, a"Soft Start"to limit the current supplied to the lamp 4 to be turned on. In the example shown, when turning on lamp 4, the current supplied to the lamp is increased gradually to produce"controlled preheating", i. e. a controlled increase in resistance, of the filament of lamp 4. Laboratory tests, in fact, have shown that"preheating"the filament when turning on lamp 4 increases the average working life of the lamp. At ambient temperature, the resistance of the filament is 10-30% of its rated steady operating value, so that, with known solutions, lamp 4 is initially supplied with very high current, and therefore subjected to thermal and mechanical stress which reduces its average working life.

As for the second critical condition, microprocessor 7, by means of power circuits 3, provides for controlling voltage, so that the supply voltage of lamp 4 is limited

at all times to an optimum reference voltage threshold value fixed, for example, at 5% below the rated supply voltage value.

Laboratory tests, in fact, have shown that, when the supply voltage of lamp 4 is 5% above the rated supply voltage, the average working life of lamp 4 is halved; whereas, when the supply voltage of lamp 4 is 5% below the rated supply voltage, the average working life of the lamp is doubled.

By means of power circuits 3, microprocessor 7 therefore maintains the supply voltage of lamp 4 at a value substantially 5% below the rated supply voltage.

It should also be pointed out that microprocessor 7 also provides for"preventive"maintenance of system 1, i. e. informs the user of the operating and work status of each lamp 4 via remote-control unit 9.

In the example shown, microprocessor 7 stores, in a memory unit (not shown), the number of on/off operations and the operating time of each lamp 4, and processes these values to determine whether the lamp in question needs changing or not.

For example, microprocessor 7 may compare the number of on/off operations and the operating time of each lamp 4 with a maximum turn-on threshold and a predetermined maximum time threshold respectively, and, depending on the outcome of the comparison, supply a user message (indicating the operating condition of each lamp), which is displayed on display device 13 of remote-control unit

9.

It should be pointed out that, by means of such processing, central control unit 5 is able to supply remote-control unit 9, via data communication device 8, with a number of information items relative to the status, e. g. end-of-life status, of lamp 4.

Central control unit 5 may preferably, though not necessarily, comprise a number of known sensors 15, e. g. optoelectronic IR or photoresistance sensors, which are connected to and supply microprocessor 7 with a signal containing information relative to the presence/absence of persons in the environment in which sensor 15 is installed, or the presence/absence of light.

Microprocessor 7 is thus able to control turn on/turn off of each lamp as a function of both the presence/absence of persons and the light intensity of the environment.

Operation of the low-voltage-lamp supply and control system is easily deducible from the foregoing description with no further explanation required.

The low-voltage-lamp supply and control system has the advantage of greatly increasing the average working life, and so reducing the maintenance cost, of lamps 4.

Low-voltage-lamp supply and control system 1 also has the advantage of greatly reducing the number of transformers 2 and voltage regulators required to supply lamps 4. Unlike known systems, in fact, which, to control each lamp independently, require a transformer and a

voltage regulator (commonly known as"dimmer") connected to the transformer primary, system 1 as described above only requires one transformer 2, thus greatly reducing the production cost of the system.

Clearly, changes may be made to the low-voltage-lamp supply and control system as described and illustrated herein without, however, departing from the scope of the present invention.

In particular, two-way data exchange between remotecontrol unit 9 and central control unit 5 may be effected by means of a 1-10 bus, Dali, x automation or similar.

Two-way data exchange between central control unit 5 and remote-control unit 9 may be effected by means of known communication standards, e. g. conveyed-wave transmission.

Finally, central control unit 5 may provide for controlling a maximum drop in the supply voltage of lamp 4, caused, for example, by the user adjusting the brightness of the lamp. The purpose of which control is prevent a"critical"undervoltage condition which may rapidly deteriorate the filament, and so reduce the average working life, of lamp 4.

More specifically, microprocessor 7 determines whether the supply voltage of lamp 4 is below a minimum "safety"threshold. And, if it is, central control unit 5 can either disable any further user command resulting in a fall in the supply voltage of lamp 4, or inform the user, e. g. by displaying an alarm message on the display

device of remote-control unit 9.

Claims

1) A system (1) for supplying and controlling lowvoltage lamps, characterized by comprising: at least one voltage transformer (2) for supplying a low voltage; a number of power circuits (3) supplied by the voltage transformer (2) and for regulating the supply voltage of said lamps (4); and a central control unit (5) for selectively controlling said power circuits (3) to regulate turn on/turn off and the brightness of each said lamp (4).

2) A system (1) for supplying and controlling lowvoltage lamps as claimed in Claim 1, characterized in that said central control unit (5) comprises two-way communication means (8) for communicating with at least one remote-control unit (9); the remote-control unit (9) supplying the central control unit (5) with control signals indicating turn on/turn off and/or brightness adjustment of any one said lamp (4).

3) A system (1) for supplying and controlling lowvoltage lamps as claimed in any one of the foregoing Claims, characterized in that said central control unit (5) comprises processing means (7) for controlling said power circuits (3) to supply a predetermined current value to each said lamp (4).

4) A system (1) for supplying and controlling lowvoltage lamps as claimed in Claim 1 or 2, characterized

in that said central control unit (5) comprises processing means (7) for controlling said power circuits (3) to maintain a predetermined supply voltage value of said lamps (4).

5) A system (1) for supplying and controlling lowvoltage lamps as claimed in any one of the foregoing Claims, characterized in that said central control unit (5) comprises memory means for memorizing the number of on/off operations and the operating time of each said lamp (4).

6) A system (1) for supplying and controlling lowvoltage lamps as claimed in any one of the foregoing Claims, characterized in that said central control unit (5) comprises sensor means (15) for supplying said processing means (7) with a signal indicating the presence of persons or the absence of light.