Patent Description:
It is known to use UV lamps with disinfectant function, since UV light is capable of deactivating or eliminating pathogenic microorganisms.

On the other hand, UV light is not suitable for lighting environments and also has potentially dangerous effects on humans too, if not properly controlled.

It is also known that certain light radiations in the visible range, particularly in the violet range, can have disinfectant effects.

For example, <CIT> discloses a lighting device comprising a first light source which emits radiation with a wavelength between <NUM> and <NUM> and has antibacterial function; and a second light source which emits radiation of a different wavelength from the first light source and such that the combination of the light emitted by the two sources generates a white light, which can therefore also be used for lighting the environment.

Further examples of this type of lighting devices, which use a light source emitting specific-wavelength violet light with disinfectant function combined with a light source emitting a complementary light resulting in white light, are described in <CIT> and <CIT>.

Also <CIT> discloses a device having a first light source with disinfecting function, that emits in a range of <NUM> to <NUM>, and a second light source that emits at a different peak wavelength so that the combined light output of the first and second light sources emits a colored light that is perceived as white light. The second light source is selected to have very specific properties in terms of color coordinates and spectral emission.

<CIT> discloses a sanitization device comprising a violet light source and a white light source in combination with a red light source (emitting at <NUM>-<NUM>) and a green light source (emitting at <NUM>-<NUM>).

<CIT> discloses a sanitization device comprising a UV light, a white light, and a green light emitting at <NUM>-<NUM>.

The known lighting devices described above, in which the white light performing the lighting function originates from the combination of light emitted by the violet source and a specially designed source, may not be fully satisfactory as regards simplicity of construction and photometric performance, particularly visual comfort, and especially in cases where it is necessary to comply with lighting standards and regulations, for example in the workplace.

It is an object of the present invention to provide a lighting device which allows the drawbacks of the prior art described herein to be overcome; in particular, it is an object of the invention to provide a lighting device which is particularly efficient, functional, and versatile.

Therefore, the present invention relates to a lighting device as defined essentially in the appended claim <NUM> and, in its additional features, in the dependent claims.

The lighting and sanitization device of the invention is simple, efficient, functional, and versatile, being able to provide both effective lighting of the environment and effective sanitization against pathogenic microorganisms.

Further features and advantages of the present invention will be apparent from the following description of a non-limiting embodiment thereof, with reference to the accompanying drawings, wherein:.

Number <NUM> in <FIG> indicates a lighting device as a whole, that is, intended for lighting environments (in particular, but not only, indoor environments).

The device <NUM> further comprises a control unit <NUM> operatively connected to the sources <NUM>, <NUM>, <NUM> for controlling the operation (switching on/off and adjusting the intensity) and optionally, an optical assembly <NUM> associated with the sources <NUM>, <NUM>, <NUM> for levelling the emission from the sources <NUM>, <NUM>, <NUM>.

Preferably, the sources <NUM>, <NUM>, <NUM> are LED light sources comprising one or more LEDs.

For example, each source <NUM>, <NUM>, <NUM> comprises a plurality of identical LEDs connected in series.

In the non-limiting example in <FIG>, the sources <NUM>, <NUM>, <NUM> are arranged on an LED board <NUM> having eight LEDs, namely: four violet-light LEDs (V), connected in series to define the source <NUM>; two white-light LEDs (W), connected in series to define the source <NUM>; two lime-light LEDs (L), connected in series to define the source <NUM>.

However, it is understood that the device <NUM> may include a different number of sources, organized according to different schemes, even on multiple LED boards.

The violet light source <NUM> emits light having a wavelength between <NUM> and <NUM>, in particular having a peak wavelength at <NUM>.

In particular, the white light source <NUM> consists of one or more white light LEDs having a color temperature ranging between <NUM> and <NUM>, preferably between <NUM> and <NUM>; and a color rendering index (CRI) ranging between <NUM> and <NUM>, preferably equal to or greater than <NUM>. In a preferred embodiment, the source <NUM> has a color temperature of <NUM> and a CRI of <NUM>.

The lime light source <NUM> (yellow-green) emits lime light having a main peak at a wavelength between <NUM> and <NUM>; and a secondary peak at a wavelength between <NUM> and <NUM>.

The use of the lime light source <NUM> allows a greater energy contribution from the violet light source <NUM>, which can result in shorter application times than a solution only providing a combination of white light and violet light. In fact, the antibacterial action is achieved by applying onto the exposed surfaces a certain irradiance value "I" (typically in the <NUM>-<NUM> band) expressed in mW/cm^<NUM> for a time "t" expressed in seconds. The result of the product I x t, or more generally the result of the integral of the irradiance over time, is an energy density value, normally expressed in J/cm^<NUM>. The energy density value is what is then placed in relation to the doses that produce bacterial population reduction effects for all those families of bacteria and microorganisms in general that are sensitive to certain wavelengths.

By way of example, in a typical daytime mode operation (<NUM> white light with the maximum permissible violet component), the device <NUM> (mounted at an intended installation height) produces an irradiance (between <NUM> and <NUM>) on the worktable around <NUM> mW/cm^<NUM>.

In daytime use (typically <NUM> hours) the energy density value will be: <MAT>.

The energy density level reached can be considered effective to reduce colony growth, at least of that portion of pathogenic bacteria most investigated by researchers and found to be sensitive to these radiations.

In night-time mode, with <NUM>% violet light alone, the irradiance on the worktable can reach values of <NUM> and <NUM> mW/cm^<NUM> and above depending on the configuration and location of the device <NUM> in the environment.

In this case, assuming a night-time use of <NUM> hours, the energy density reaches levels of about <NUM> J/cm^<NUM>, i.e., values sufficient to reduce the photosensitive bacterial colonies according to trajectories linked to the different families of bacteria with which one has to deal.

In a preferred embodiment, but not necessarily, the lime light source <NUM>, according to the CIE <NUM> diagram, has the following color coordinates: <MAT> <MAT>.

The use of said source enables a higher percentage of violet light than a traditional white-violet system, since the lime color is opposite the violet color in the color diagram.

Since, in the daytime mode, the goal is to have a resultant on the black body curve, the violet light needs to have a higher power to contrast the color of the white-lime mix that is located in the white-green region.

In a preferred embodiment, the sources <NUM>, <NUM>, <NUM> are characterized by spectral power distributions shown in the graphs of <FIG>, <FIG> and <FIG>, respectively (which show the wavelength on the abscissa and the normalized radiant flux of the respective light source on the ordinate).

The lime light source <NUM> has the purpose of balancing in the color space the effect induced by the violet light emitted by the violet light source <NUM>, having a disinfectant function, on the color coordinate of the white light emitted by the white light source <NUM>.

In this way, the light emission from the device <NUM> is perceived by the observers as white light, despite the presence of the violet component.

<FIG> shows the graph of the spectral power distribution of the device <NUM> in a first mode of operation, in which the device <NUM> operates in lighting mode, being able to light the environment in which it is located with white light while providing an effective sanitization function.

In this mode, the sources <NUM>, <NUM>, <NUM> are all active: if necessary (depending on the installed sources and their power), the control unit <NUM> controls a different percentage of activation of each source <NUM>, <NUM>, <NUM> so that the resulting light is white light.

Advantageously, the violet light source <NUM> is oversized with respect to the lighting requirement.

The device <NUM> is therefore configured so as to operate - controlled by the control unit <NUM> - in at least two operating modes:.

In the embodiment referred to in <FIG>, with the sources indicated above by way of example, in the lighting mode, the sources <NUM>, <NUM> are active at <NUM>% of their power, whereas the source <NUM> is active at <NUM> of the available power.

Clearly, the percentage of activation of the sources <NUM>, <NUM>, <NUM> controlled by the control unit <NUM> so that the device <NUM> emits white light as a whole depends on the specific sources used and can vary with respect to what is described herein purely by way of example.

In any case, the control unit <NUM> is configured to selectively activate the sources <NUM>, <NUM>, <NUM> in a combined manner to provide an overall emission of white light.

The effect is illustrated in the graphs of <FIG> and <FIG>, where two limit curves are shown on the X, Y CIE <NUM> color coordinate plane, respectively indicated as Series <NUM> and Series <NUM>, corresponding to the color limits within which the color of the light emitted must fall in order to comply with the regulations in force for lighting devices.

<FIG> indicates the color point of the light emitted by the device <NUM>, with the lime light source <NUM> off and the sources <NUM>, <NUM> on: the color point is outside the limits provided.

Instead, <FIG> indicates the color point of the light emitted by the device <NUM>, with the lime light source <NUM> on, together with the sources <NUM>, <NUM>: the color point is within the limits provided.

According to the invention, the presence of the lime light source <NUM> compensates for the violet light from source <NUM> so that the overall emission of the device <NUM> is perceived by the human eye as white light, and at the same time the device <NUM> provides a sanitizing effect induced by the violet light component.

Preferably, in order to improve the quality of the emitted light and also the overall efficiency of the device <NUM>, a white light source <NUM> is selected, which has specific color temperature and spectrum characteristics (color rendering) and is capable of integrating the violet-lime component, and as a final result, to attain a white light of the desired quality. In fact, the balance provided by the lime light source <NUM> with respect to the light emitted by the violet light source <NUM> balances the energy and color aspects but may be insufficient to provide adequate light for the environment lighting requirements.

The relative weights of the sources <NUM>, <NUM>, <NUM> can also be varied and selected: it is possible to obtain the desired emission by varying the number of the sources <NUM>, <NUM>, <NUM> and their power supply currents.

From the electrical management point of view, the three sources <NUM>, <NUM>, <NUM> can be controlled by a two-channel system, where the sources <NUM> and <NUM> are managed by a first channel, and the violet light source <NUM> by a second channel).

It is understood that other configurations may be used, for example series-parallel solutions or high voltage solutions that may be specific to the characteristics of the violet LEDs, in particular, and their limited availability for electrical parameter selections.

On the other hand, in order to have the maximum possible sanitizing effect, the control unit <NUM> controls the sources <NUM>, <NUM>, <NUM> so that the source <NUM> is <NUM>% active, while the sources <NUM>, <NUM> are off. Clearly, in this mode of operation, the device <NUM> does not provide suitable light for environment lighting.

The sole sanitization mode can be provided, for example, in the absence of people in the environment where the device <NUM> is installed.

For this purpose, in addition to a manual control operated by a user, the device <NUM> can be equipped with or connected to one or more sensors, for example, presence sensors, capable of detecting whether there are people in the environment where the device <NUM> is located and communicating the detection to the control unit <NUM>, which adjusts the operating modes of the device <NUM> accordingly.

Generally, the control unit <NUM> is configured so as to selectively activate the sources <NUM>, <NUM>, <NUM>, also independently from one another, and optionally to further adjust the light intensity and/or emitting power of each source.

In this way, for example, the device <NUM> can be operated in the lighting mode with a sanitizing function (with all the sources <NUM>, <NUM>, <NUM> switched on); or in the sanitizing mode alone (with the sole violet light source <NUM> switched on).

The control unit <NUM> is configured to activate the sources <NUM>, <NUM>, <NUM> according to a preset program, optionally including a time profile, so as to adjust the light emission of the device <NUM> according to different lighting requirements throughout the day and/or according to the place where the device <NUM> is installed; and/or according to signals received from sensors connected to the control unit <NUM>.

The control unit <NUM> can also be configured so as to manage the transition from one operating mode to the other depending on the presence of people, until a daily dose is reached, in combination with sensors and programming. In particular, when the presence of people is detected, by means of presence sensors, the control unit <NUM> commands the switching on of the violet light source <NUM> so that its emission is within a predetermined threshold.

In the embodiment of <FIG>, the lighting device <NUM> further comprises a UV source <NUM>, in particular a source emitting UV-C radiation, which replaces all or part of the violet light emitted by the violet light source <NUM>.

For example, sources <NUM> may be used, which emit UV-C radiation with the spectral emission shown in <FIG> shows the spectra (again in terms of spectral power distribution) of the UV-C radiation emitted by an LED source with a peak wavelength at <NUM>); and by a low-pressure mercury tubular source with a peak wavelength at <NUM>.

The control unit <NUM> of the device <NUM> is configured so as to selectively activate the violet light source <NUM> and/or the UV source <NUM>, according to a preset program, optionally including a time profile, so as to take into account different lighting requirements throughout the day and/or according to the place where the device <NUM> is installed; and/or according to signals received from sensors (in particular, presence sensors detecting the presence of people in the lighted environment) connected to the control unit <NUM>.

Conveniently, considering the greater potential danger of UV radiation to people, the activation of the UV source <NUM> is controlled by the control unit <NUM> based on the actual presence of people in the environment and/or for adequate and safe periods of time.

Optionally, the control unit <NUM> can be preset to activate the source <NUM> also based on the place where the device <NUM> is installed: if in the environment there are suitable materials and finishes and the space has dimensions suitable for the use of UV radiation, possibly for predetermined times.

As previously described, the activation of the UV source <NUM> can also be suitably controlled according to the signals received from sensors connected to the control unit <NUM>, as well as on preset time profiles. In addition to presence detectors of various types, the control unit <NUM> can be connected to entry authorization systems and/or systems for detecting the presence of smart devices in the environment, or the like. Preferably, a redundancy of detection systems ensures correct operation of the UV sources in complete safety for people.

The control unit <NUM> controls the device <NUM> also to integrate the violet light source <NUM> and the UV source <NUM>. In particular, if the use of the sole violet light generated by the source <NUM> is not fully effective in the sanitizing function, because the time available is not sufficient for the violet light radiation to develop its action on micro-organisms, for example, then the control unit <NUM>, in addition to the source <NUM>, operates the UV source <NUM> too.

The control unit <NUM> allows the source <NUM> to be operated only if the conditions allow it and/or for a suitable period of time, always checking that conditions of safe use (presence of people, presence of suitable materials and finishes, sufficient spaces, etc.) are met.

The combined use of UV radiation, in particular UV-C, and violet light allows effective elimination of pathogens (ensured by UV radiation), whereas the violet light (compensated by the lime light) maintains a function of containment of bacterial regrowth, as well as contributing to functional lighting.

Claim 1:
A lighting and sanitization device (<NUM>), comprising: a first light source (<NUM>) emitting violet light having a wavelength between <NUM> and <NUM>; characterized by comprising a second light source (<NUM>) emitting white light; and a third light source (<NUM>) emitting lime light having a peak wavelength between <NUM> and <NUM>.