Field of the invention The present invention relates to a luminous intensity adjustment method in discharge lamps, in particular fluorescent lamps, for example to generate luminous effects.

The invention relates also to a device that carries out this method.

Description of the prior art The need is felt of luminous intensity adjustment coming from discharge lamps, for example T5 tubes, T8 tubes, compact tubes, etc.

Applications that would profit of the adjustment are for example: - luminous intensity adjustment responsive to the external light that enters an room (for example dawn, sunset) ; - luminous effects in expositions, shops, stands, multi-functional halls etc.; - automatic turning on and off light spots (jointly with light sensors and presence sensors).

As known different devices exist for adjusting the intensity and light power in discharge tubes. They comprise usually several elements and in particular: - a computing unit for generating the luminous effect; - software and hardwares interface for programming timing changes ; - a swap relais for cyclical repetition of the effect; - two signal encoders for generating an output reference voltage ; - a transmission bus for coupling the computing unit to the converter.

The state of the art configurations are expensive owing to the high number of components and the need for expensive equipment and complex programming of the software and of the clock signal generation.

Alternatively, prior art solutions use high voltage control units (higher than 1000 V). In this case the problems arise of difficult availability of components, since high voltage lamps dedicated for each single application are required, of high energy consumption and high risks concerning high electrical fields.

Furthermore, the existing devices do not provide at the same time the above described functions.

Summary of the invention It is therefore a feature of the present invention to provide a method for adjusting luminous intensity responsive to time in discharge lamps.

It is another feature of the invention to provide such a method that allows to overcome the above described problems of the prior art.

It is a further feature of the invention to provide such a method that adjusts the light intensity easily and cheaply, carrying out the above applications.

It is a first particular feature of the invention to provide a device for luminous intensity adjustment in discharge lamps that allows to carry out the above method using less components and with the possibility of being associated, for generating the luminous effects, to easy fluorescent tubes, for example T8 tubes coupled to electronic dimmerable reactors.

It is another particular feature of the present invention to provide a device as above indicated that requires low investment costs for replacing existing lighting components and systems with more efficient ones such as lamps, power suppliers, lighting bodies and

regulators.

A further feature of the present invention is to provide a device that allows programming its control components in a way much easier and less expensive with respect to the solutions of prior art.

A further feature of the present invention is that of allowing more energy saving, requiring less supply voltage than the solutions of prior art ; the use of lower supply voltage allows also to increase the electrical safety.

These and other features are accomplished with one exemplary luminous intensity adjustment method in discharge lamps, said lamps comprising: - a discharge light body having two electrodes ; - an electronic reactor suitable for providing a voltage to said electrodes at a determined frequency and for modulating said voltage and said frequency to obtain a predetermined illumination of said body, said reactor having an analog voltage input suitable for receiving a predetermined voltage signal ; whose main feature is that it comprises the steps of: - reading an external input parameter P; - running a control routine for causing said predetermined voltage signal to follow a function F (t, P) responsive to said parameter and to time.

Preferably, said function F (t, P) is selected from the group: - fading/rising ; - compensation between external light and artificial light in an room; - luminous effects as predetermined sequences or random.

Advantageously, external parameter P can be selected from the group:

- presence of people; - room light intensity; - remote control signal; - predetermined automatic signal; - room temperature ; - temperature of the light body; - position data ; - colour of the light body.

In particular, if external parameter P is related to the temperature of the room in which the light body is installed, a step is provided where the temperature value is filtered and used for changing suitably the operation of the electronic reactor in order to obtain at a desired temperature the maximum efficency.

Advantageously, on the basis of the temperature value of the light body it is possible valutare the lighting efficiency, to know the wear of the lamp, to determine possible faults of the device and optimizing the heat dissipation of the possible support on which the lamp is installed.

In particular, the position data allows to calculate the height of installation of the device on the basis of which it is possible to set control parameters.

Advantageously, the data relative to the colour of the installed lighting bodies allows to drive the different gradations to obtain a predetermined colour temperature (hot-cold light).

Advantageously, the step is provided of generating a feeding voltage and a reference voltage through feeding means operatively connected to the electrical network by a transformer.

Advantageously, it is possible to set at least one parameter by an user by at least a first variable resistor and a second variable resistor that cooperate with a DIP

switch.

Preferably, the first and the second variable resistors are potentiometers consisting of printed circuit trimmers, provided also as remotable.

Advantageously, a step is provided wherein one form of square wave is selected by the DIP switch, said shape of square wave being then recorded in a read only memory (ROM).

In particular, a step is provided where the shape of square wave is read by a microcontroller.

Advantageously, the shape of square wave can be characterized by the user setting the ON and OFF periods adjusting said first and said second adjustable resistor, for example two trimmers, suitable for determining the time that employ the ramps to achieve the minimum and maximum values that cause in turn the maximum and minimum intensity of light.

Preferably, the software contained in the microcontroller provides the steps of: - initialising the microcontroller ; - initialising the functional variables ; - reading the values chosen by the first trimmer ; - setting the first analog value ; - reading the values chosen by the second trimmer ; - setting the second analog value ; - reading the values chosen by the DIP switch; - setting the predetermined subroutine; - carrying out a routine with generating the output analog signals; - control of the process advancement; - increment of the process advancement.

According to another aspect of the invention, a device for adjusting the luminous intensity in discharge lamps comprises means for carrying out the above described

method.

In particular, the device can provide at least one sensor suitable for measuring a temperature value of the external room. This sensor can be interfaced with control units of fire detection.

Advantageously, the device can comprise a heat sensor suitable for measuring a temperature value of the light body.

Furthermore, a position sensor can be provided suitable for measuring data relative to the height of installation of the system and for transmitting it to the software that sets automatically control parameters.

Finally, a colour sensor can be provided suitable for measuring at least one value relative to the colour of each installed light body and to drive different gradations to obtain a predetermined colour temperature (hot-cold light).

Advantageously, the device has a 12 V AC output port and an analog/digital conversion circuit.

Advantageously, the microcontroller responsive to the input wave shape generates the bits necessary for the voltage control of the electronic dimmerable reactors connected to the output ports of the device variable between 1V and 10V.

Preferably, the level of predetermined voltage is selected by an external DIP switch.

Alternatively, the level of predetermined voltage is selected by a strip with relative closure jumper on printed circuit. This allows the device according to the present invention to be programmable in all the variables-times.

In an exemplary embodiment of the invention, the DIP switch is of the type with four combinations and is suitable for selecting four independent voltage/brightness

characteristics for fluorescent tubes.

Brief description of the drawings Further characteristics and the advantages of the method and of the apparatus according to the invention will be made clearer with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings, in which like reference characters designate the same or similar parts, throughout the figures of which: - figure 1 shows the logic functional succession through which the luminous intensity adjustment method is operated in fluorescent lamps according to the present invention; - figure 2 shows a diagrammatical top plan view of an embodiment of the adjusting device according to the invention; - figure 3 shows a block diagram of the software of an embodiment of the adjusting device according to the invention ; - figure 4 shows a diagrammatical electrical scheme of a practical embodiment of the adjusting device of the present invention; - figure 5 shows a diagrammatical partial view of the device according to the invention.

Description of a preferred exemplary embodiment With reference to figure 1, a device 1 of the present invention has the task of adjusting the light intensity of several groups of fluorescent tubes independently supplying to them a control voltage.

In figures 1 and 2, a functional logic of the device 1 according to the present invention as a block diagram and as a diagrammatical view of the device 1 are respectively diagrammatically shown. A supply block 101 is connected by a transformer 201 to an electrical network (220/240V 50Hz AC)

and generates a +5V DC feeding voltage and a DC +12V reference voltage.

A first potenziometer 102, a second potenziometer 103 and a DIP switch 104 allow to set parameters predetermined by the user. In particular, two potentiometers 102 and 103 comprise preferably two printed circuit trimmers 202 and 203, provided also as remotable.

DIP switch 204 has four combinations and is used for selecting four respective independent voltage/brightness characteristics for fluorescent tubes.

A microcontroller 105, in combination with a digital/analog converter 106, generates a control voltage.

Such voltage is preferably generated by a 8 bit OTP RISC microcontroller 205 and by a digital/analog conversion circuit 206 having 255 levels. By microcontroller 205 the shape is read of a square wave recorded in a read only memory (ROM) and selected by DIP switch 204 ; this wave has the possibility of being defined by the user, through setting ON and OFF periods by adjusting the two trimmers 202 and 203 so that the time is chosen that the ramps employ to achieve minimum and maximum values that give a maximum and minimum intensity of light respectively.

An exemplary time has been chosen carrying out the present invention as 0 to 5 seconds for each turning on and off ramp, which are exactly symmetrical responsive to light variation, as well as a 1 to 16 seconds time was chosen for total turning on and off cycle, which are symmetrical.

A microcontroller 205 is provided, responsive to the input wave shape, generates the suitable bits necessary for a voltage control of the electronic dimmerable reactors 209, which are connected to channels output block 108 consisting of output ports 208 of the

device 1, variable between 1V and 10V. The level of predetermined voltage is preferably selected by an external DIP switch 210 or by a strip with relative closure jumper on printed circuit. This allows the device 1 according to the present invention of being programmable in all the variables-times.

The software, whose block diagram is shown in figure 3, inserted in microcontroller 205, according to this embodiment of the present invention, allows to obtain, among others, the functions of: - fading effect; - dawn-sunset effect; - play of light, for example, luminous signs, shop windows, fair stands, multi-functional rooms ; - control of the light intensity for energy optimizing responsive to the natural light present in the room; - turning on and off automatic light spots (jointly with light sensors and presence sensors).

As above said, digital/analog converter 106 comprises a 8 bit digital/analog conversion circuit 206 with 255 combinations, enough for a good resolution with a 10V maximum output. In this circuit output bits of the microcontroller 205 are turned into a analog signal to them proportional. This analog signal is the control voltage.

A ramps linearisation and amplification block 107 provides a circuit 207 for transforming, by an operational amplifier, the +5V output of the digital/analog conversion circuit 206 into a +10V signal necessary for adjusting the electronic dimmerable reactors 209 of the output load of device 1 of the present invention

and connected to channels output 108 consisting of output ports 208. Circuit 207 provides, furthermore, a current alike to current 10 but suitable for piloting five external devices.

Device 1 furthermore, has a 12V AC output port 212 and an analog/digital conversion circuit 211. Figure 3 shows a flowsheet of the software residing in microcontroller 205 and that provides the steps of: - initialising (F301) microcontroller 205 ; - initialising (F302) functional variables; - reading (F303) values chosen by the first trimmer 202; - setting (F313) a first analog value ; - reading (F304) values chosen by the second trimmer 203; - setting (F314) a second analog value; - reading (F305) values chosen by DIP switch 204 ; - setting (F315) a predetermined subroutine ; - running (F306) the subroutine with generation of output analog signals; - controlling (F307) the process advancement ; - incrementing (F308) the process advancement.

In figure 5 a fluorescent lamp 400 is diagrammatically shown wherein, as well known, the light is delivered by fluorescent particles activated by UV energy emitted by a mercury arch generated when a measured voltage between two electrodes 401 and 402 is established and a current crosses the mercury vapour. Lamp 400 is associated to an electronic reactor 209 that stabilises the current at a determined value to which the best operating conditions correspond. In particular, reactor 209 generates a voltage which is high enough for carrying out the

trigger of the lamp and then limits the current at a predetermined value, to which an operative voltage is associated lower than the triggering voltage. Electronic reactor 209 has an analog voltage input suitable for receiving a predetermined voltage signal. This voltage signal, as previously said, is generated by reading an external input parameter P executed by a circuit (block 410) containing microcontroller 205. Then a control routine is run for causing said predetermined input voltage signal of reactor 209 to follow a function F (t, P) responsive to parameter P and to time. External parameter P can be selected from the group: - presence of people ; - room light intensity ; - remote control signal; predetermined automatic signal ; - room temperature; - temperature of the light body; - position data ; - colour of the light body.

In particular, according to the type of external parameter P dedicated sensors are provided operatively connected to circuit 410. In case the parameter P of interest is room temperature a heat sensor 415 is provided. In the case, instead, the parameter P of interest is the temperature of light body 400, a heat sensor is provided 420 connected to it. Instead, if the position of the lamp 400 in the room is sough, and in particular the height at which it is located, in order to optimize the light intensity, a position sensor 425 can be provided. The use of a position sensor is particularly advantageous if the lamp 400 is mounted on a mechanism that causes it to move, for example a

crane, in particular for changing its working height.

Furthermore, a colour sensor can be provided 430 for measuring at least one value relative to the colour of the light body 400 and for driving light gradation changes in order to obtain a desired"colour temperature". The"quality"of the light, in fact, is essentially responsive to colour and shade which depend from the"colour temperature", normally espressa in Kelvin degrees. According to the colour temperature the light shadeis defined"warm","white"or"cold". The sensors above described can be used separately, or alternatively, contemporaneously. Furthermore, what above said with reference to a fluorescent lamp is to be intended valid also for any desired discharge lamp.

The foregoing description of a specific embodiment will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such an embodiment without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiment. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.