WO2017162548A1

WO2017162548A1 - Lighting device and lamp and luminaire comprising the lighting device

Info

Publication number: WO2017162548A1
Application number: PCT/EP2017/056492
Authority: WO
Inventors: Rifat Ata Mustafa Hikmet; Ties Van Bommel
Original assignee: Philips Lighting Holding B.V.
Priority date: 2016-03-24
Filing date: 2017-03-20
Publication date: 2017-09-28

Abstract

A lighting device (100) is disclosed, comprising at least one first light source (110) configured to emit light (115) within a first wavelength range and at least one second light source (120) configured to emit light (125) when operated within a second wavelength range, wherein the second wavelength range is different from the first wavelength range and the first wavelength range includes shorter wavelengths as compared to the second wavelength range. The at least one first light source (110) is configured such that the intensity of the light emitted by the at least one first light source (110) spatially varies according to an intensity pattern.

Description

Lighting device and lamp and luminaire comprising the lighting device

TECHNICAL FIELD

The present invention relates to a lighting device which may be capable of providing desired lighting effects and appearances in various lighting applications such as, for example, retail and entertainment.

BACKGROUND

White light can be produced for example by using RGB light emitting diodes (LEDs), or by partial phosphor conversion of blue LED light to longer wavelengths. In this way, light on the black body locus (BBL), which may also be referred to as the Planckian locus, exhibiting a color rendition index (CRI) of 80 or more, or even a CRI of 90 or more, at any correlated color temperature (CCT) may be produced. For example in lighting applications such as retail and entertainment, it may be desirable to create lighting effects and appearances e.g. for decorative purposes, which may be attractive for an observer such as a shopper and which may catch the attention of the observer.

WO 2015/170214 Al discloses a method for far field illumination using modified optical elements that normalize the angular distribution of light of different colors. WO 2015/170214 Al further discloses a lighting unit which includes a plurality of light sources emitting light of different colors, where each of the light sources is associated with a respective optical element. Each optical element is optimized to modify the angular distribution of light emitted from the light source such that the angular distribution of each of the light sources in the far field is substantially similar.

SUMMARY

The applicant has found that when such white light sources, which hence for example may employ RGB LEDs or partial phosphor conversion of blue LED light to longer wavelengths, are provided with blue light of relatively short wavelengths (e.g., between about 400 nm and about 440 nm), the white light source may exhibit a more attractive white appearance to an observer. White light usually has a wavelength of about 440 nm or longer. White light with a 'crisp white light' effect is light which has a short wavelength blue light component including visible light having a wavelength of 440 nm or shorter. For example, it has been found that an object may appear whiter if it appears slightly chromatic with a blue tint, and that a bluish color may be perceived as whiter than a color point on the BBL. A 'crisp' white light may therefore be obtained by tuning the color point of a light source below the BBL by addition of deep blue which is allowed to form part of the total output spectrum.

In view of the above discussion, a concern of the present invention is to provide a lighting device which may be capable of providing desired lighting effects and appearances in various lighting applications such as retail and entertainment.

A further concern of the present invention is to provide a lighting device which may be capable of emitting light exhibiting a 'crisp white light' effect.

To address at least one of these concerns and other concerns, a lighting device in accordance with the independent claim is provided. Preferred embodiments are defined by the dependent claims.

According to a first aspect of the present invention a lighting device is provided. The lighting device comprises at least one first light source, which is configured to emit light when operated within a first wavelength range, and at least one second light source, which is configured to emit light when operated within a second wavelength range. The second wavelength range is different from the first wavelength range. The first wavelength range includes shorter wavelengths as compared to the second wavelength range. The lighting device is configured to emit a combination of light emitted by the at least one first light source and light emitted by the at least one second light source when the at least one first light source and the at least one second light source, respectively, are operated, such that light emitted by the lighting device (e.g., in the far field) comprises wavelengths included in the first wavelength range and in the second wavelength range. The at least one first light source is configured such that the intensity of the light emitted by the at least one first light source spatially varies according to an intensity pattern.

Embodiments of the present invention are based on an idea of combining or superimposing or overlapping light emitted by a first light source at a first wavelength range with spatially patterned light emitted by a second light source at shorter wavelengths compared to the first light source. The second light source may for example emit white light having a wavelength within a wavelength range from 440 nm to 800 nm, and the first light source may emit a short wavelength blue light having a wavelength within a wavelength range from 400 nm to 440 nm. The first light source may for example comprise a laser light source, and the second light source may for example comprise a LED-based light source, by means of which a spatially patterned light having a relatively high spatial resolution may be produced for a patterned appearance on an illuminated surface. By superimposing or combining or overlapping a pattern of a short wavelength blue light, for example having a wavelength within a wavelength range from 400 nm to 440 nm, on or with white light, for example having a wavelength within a wavelength range from 440 nm to 800 nm, the lighting device may be capable of emitting light exhibiting a 'crisp white light' effect.

The at least one first light source may be configured such that the intensity of the light emitted by the at least one first light source varies in the far field thereof according to an intensity pattern. In the context of the present application, by the term far field it is meant the area outside the near field of the at least one first light source, e.g., within a distance less than the wavelength of light emitted by the at least one first light source. For example for the case where the at least one first light source is constituted by a laser, or laser diode, the far field is outside the Rayleigh range of the laser beam emitted by the laser or laser diode.

The lighting device comprises at least one first light source which can emit light within a first wavelength range and at least one second light source which can emit light within a second wavelength range, with the first wavelength range including shorter wavelengths as compared to the second wavelength range. By way of the first wavelength range including shorter wavelengths as compared to the second wavelength range and by the at least one first light source being capable of emitting patterned light, a 'crisp' white light effect in the light output from the lighting device may be obtained, which may allow for or facilitate providing desired lighting effects and appearances in various lighting applications such as retail and entertainment.

In the context of the present application, by the first wavelength range including shorter wavelengths as compared to the second wavelength range it may be meant that the first wavelength range is lower than the second wavelength range in the

electromagnetic spectrum, e.g. in the part of the electromagnetic wavelength spectrum including visible light. The first wavelength range may have an emission peak at a shorter wavelength as compared to an emission peak of the second wavelength range. The first wavelength range and the second wavelength range may be non-overlapping. However, there may possibly be some overlap between the first wavelength range and the second wavelength range.

The at least one first light source and/or the at least one second light source may for example be configured such that the first wavelength range includes shorter wavelengths as compared to the second wavelength range. To that end, the at least one first light source and/or the at least one second light source may for example comprise wavelength converting material configured to convert at least a part of light input therein into light having a selected wavelength range. The wavelength converting material could for example comprise photo-luminescent material. According to another example, the at least one first light source and/or the at least one second light source may comprise at least one optical filter, such as, for example a dichroic filter and/or a dichroic mirror, or any other type of optical filter capable of transmitting incident light having a wavelength within a selected wavelength range through the optical filter.

In the context of the present application, by the at least one first light source being configured such that the intensity of the light emitted by the at least one first light source spatially varies according to an intensity pattern, it is meant that the light emitted by the at least one first light source comprises spatially patterned light, for example such that a beam of light from the at least one first light source incident on a surface of an illuminated object in the far field has a varying intensity pattern over the portion of the illuminated surface. A beam of light from the at least one first light source which is incident on a surface of an illuminated object may hence not exhibit a spatially uniform intensity. For example, the intensity of the light which may be emitted by the at least one first light source may vary along an axis x on or across an illuminated surface of an object that is illuminated by the at least one first light source so that the intensity has a series of alternating 'dips' and 'peaks', possibly such that the intensity for example has more than four peaks along the axis x, or preferably more than ten peaks along the axis x, or most preferably more than twenty peaks along the axis. Such 'dips' and 'peaks' in the intensity may in the light of the foregoing description for example be included in short wavelength blue light, having a wavelength within a wavelength range from 400 nm to 440 nm, which may be emitted by the at least one first light source. According to one or more embodiments of the present invention, the intensity pattern (e.g., of short wavelength blue light, possibly having a wavelength within a wavelength range from 400 nm to 440 nm) comprises a laser pattern such as, for example, a speckle pattern.

The (possibly white) light from the at least one second light source may be non-patterned light. That is, the light emitted by the at least one second light source may not be spatially patterned light but may exhibit a spatially uniform intensity.

The intensity pattern of the light emitted by the at least one first light source may for example be a predefined or a selected intensity pattern. The at least one first light source may be configured such that the intensity pattern is controllable, or adjustable. To that end, the at least one first light source may for example comprise a laser (e.g., comprising one or more laser diodes). A laser may be able to produce patterns of crispy white light and normal white light having a relatively high spatial resolution for a patterned appearance on an illuminated surface. A relatively high spatial resolution may be obtained since laser light from laser diodes generally is highly collimated. This is due to that the laser light is formed in an optical cavity. When laser light from laser diodes is combined with a suitable optical element such as a diffractive element, a pattern of crispy white light and normal white light having relatively high spatial resolution may be obtained for a patterned appearance on an illuminated surface. A laser may be able to relatively easily produce a speckle pattern on an illuminated surface. Speckle is a particular form of sparkling appearance. The speckle pattern can be augmented or enhanced by using a suitable optical element such as a diffuser. A laser may be able to produce a variety of patterns on an illuminated surface in a dynamic manner by means of using a switchable optical element, which for example may comprise a motor or a non- mechanical means such as a liquid crystal based cell. In order to achieve such lighting effects and appearances, the lighting device may comprise at least one optical element, which may be arranged so as to receive at least a portion of the light emitted by the at least one first light source and output optically modified light.

There may be more than one first light source and/or more than one second light source comprised in the lighting device. The lighting device may be configured to emit a combination of light emitted by the first light source(s) and light emitted by the second light source(s) when the first light source(s) and the second light source(s), respectively, are operated.

In order to allow or facilitate for the lighting device to be able to emit a combination of light emitted by the at least one first light source and light emitted by the at least one second light source when the at least one first light source and the at least one second light source, respectively, are operated, some appropriate light combining means, for example such as known in the art, may be employed. In alternative or in addition, the at least one first light source may be arranged relatively to the at least one second light source, or vice versa, in a suitable manner, so that the lighting device can emit a combination of light emitted by the at least one first light source and light emitted by the at least one second light source. The lighting device may for example comprise a housing for accommodating the at least one first light source and the at least one second light source. The housing and/or the at least one first light source and/or the at least one second light source may be arranged so that the combination of light emitted by the at least one first light source and light emitted by the at least one second light source when the at least one first light source and the at least one second light source, respectively, are operated is exiting the same light output or light exit, which may be arranged in the housing.

As indicated in the foregoing, the lighting device may comprise at least one first optical element. The at least one first optical element may be arranged so as to receive at least a portion of the light emitted by the at least one first light source, and to modify or manipulate the received light. The at least one first optical element may for example comprise at least one of: at least one diffractive optical element, at least one refractive optical element, at least one diffusive optical element, or at least one switchable optical element.

By means of at least one diffractive optical element it may be facilitated to obtain a pattern of crispy white light and normal white light having relatively high spatial resolution for a patterned appearance on an illuminated surface, in particular for the case where the at least one first light source comprises a laser. By means of at least one diffusive optical element it may be facilitated to augment or enhance a speckle pattern on an illuminated surface, in particular for the case where the at least one first light source comprises a laser. By means of at least one switchable optical element a variety of patterns on an illuminated surface may be produced in a dynamic manner. The at least one switchable optical element may for example comprise a motor or non-mechanical means such as a liquid crystal based cell, which may be possibly controllably switched between different optical states by controllably applying an electrical field to the liquid crystal based cell. The at least one switchable optical element may for example be switched at a switching rate the less than 60 Hz, more preferably less than 10Hz, or most preferably less than 1 Hz.

The lighting device may comprise at least one second optical element (which may be different from the at least one first optical element). The at least one second optical element may be arranged so as to receive at least a portion of the light emitted by at least one of the at least one first light source or the at least one second light source, and to modify or manipulate the received light. In alternative or in addition the at least one second optical element may be arranged so as to receive at least a portion of the light emitted by or output from the first optical element and to modify or manipulate the received light. The at least one second optical element may for example comprise a collimating and/or focusing optical element, such as, for example at least one lens, or a system of optically coupled lenses. The collimating and/or focusing optical element may for example facilitate focusing a patterned, relatively short wavelength blue light which may be emitted by the at least one first light source onto a surface of an object that is illuminated by the lighting device.

The at least one first optical element and/or the at least one second optical element may be removably, or releasably, arranged in the lighting device. In the context of the present application, by the at least one first optical element and/or the at least one second optical element being removably or releasably arranged in the lighting device, it is meant that the at least one first optical element and/or the at least one second optical element is not fixedly arranged in the lighting device, but that it/they is/are arranged in the lighting device such that it/they may be removed from the lighting device and exchanged for another

(exchangeable or removable) optical element in the lighting device, for example in order to customize or upgrade or provide new or additional optical functionality in the lighting device. By way of the at least one first optical element and/or the at least one second optical element being removably or releasably arranged in the lighting device, it may allowed or facilitated to relatively easily exchange an optical element which is used in the lighting device for another optical element when or whenever the latter one is desired to be used in the lighting device. In order to removably or releasably arrange the at least one first optical element and/or the at least one second optical element in the lighting device any appropriate fastening means or fastening element, for example such as known in the art, may be used. Such fastening means or fastening element may according to non-limiting examples for example comprise one or more clamps, clips, etc.

The lighting device may comprise at least one sensor. The at least one sensor may be for example configured to sense presence of at least one person in a region

surrounding the lighting device. A region surrounding the lighting device should in the context of the present application be understood as a certain area around a position or location of the lighting device, e.g. an area within a radius of one or a few meters from a position or location of the lighting device. The at least one sensor may for example comprise a presence or motion sensor. Presence or motion detectors or sensors may use different techniques for detecting presence or motion. Examples include but are not limited to Passive Infrared detectors, Ultrasonic motion detectors, detectors based on a combination of Passive Infrared and Ultrasonic techniques, and camera-based sensors. Further examples include detectors based on radar, sound and pressure. The lighting device may comprise a control unit. The control unit may be communicatively coupled to the at least one first light source. In addition or in alternative, the control unit may be communicatively coupled to the at least one sensor and/or the at least one second light source. The communicative coupling between the control unit and the at least one first light source, and/or the at least one sensor and/or the at least one second light source, may for example be achieved or implemented by way of any wired and/or wireless communication technique or communication means as known in the art. The control unit may be configured to control operation of the at least one first light source, and/or possibly the at least one second light source or another component of the lighting device. The operation of for example the at least one first light source may possibly be controlled by means of the control unit based on information regarding presence of any person(s) in the region obtained by the at least one sensor when carrying out the sensing(s).

Light having relatively short wavelengths may not always be desirable, because it may under certain circumstances harm the eyes of a person looking into the light. To that end, the first light source may be switched off when or whenever a person is relatively close to the lighting device (or the first light source). According to one or more embodiments of the present invention, when or whenever a person is relatively close to the lighting device, relatively short wavelength blue light which may be emitted by the at least one first light source is switched off. The color point of the light emitted by the lighting device may then be corrected by longer wavelength blue in the light emitted by the at least one second light source. For example, the control unit may be configured to, on a condition that the presence of at least one person within a selected distance from the lighting device (or from the at least one sensor or the at least one first light source) is sensed by the at least one sensor, control operation of the at least one first light source such that it does not emit light, and otherwise control operation of the at least one first light source such that it emits light.

In alternative, the control unit may be configured to, on a condition that the presence of at least one person within a selected distance from the lighting device (or from at least one sensor or the at least one first light source) is sensed by the at least one sensor, control operation of the at least one first light source such that it emits light, and otherwise control operation of the at least one first light source such that it does not emit light. This may be useful in case light having relatively short wavelengths may damage a product which is being illuminated by the lighting device. When or whenever a person is relatively close to the lighting device (or the first light source), the first light source may be switched on.

According to one or more embodiments of the present invention, when or whenever a person is relatively close to the lighting device, relatively short wavelength blue light which may be emitted by the at least one first light source is switched on. Thereby, the period of time during which the product is exposed to relatively short wavelength blue light may be kept relatively short. The color point of the light emitted by the lighting device may then be corrected by shorter wavelength blue in the light emitted by the at least one first light source.

The at least one first light source may be configured such that the intensity pattern is controllable or adjustable. The lighting device may comprise a control unit which may be communicatively coupled to at least the at least one first light source. The

communicative coupling between the control unit and at least the at least one first light source may for example be achieved or implemented by way of any wired and/or wireless communication technique or communication means as known in the art. The control unit may be configured to control operation of the at least one first light source at least with respect to the controlling or adjusting of the intensity pattern of the light emitted by the at least one first light source.

The lighting device may comprise at least two first light sources. Each of the at least two first light sources may be configured such that the intensity pattern of the light emitted by the first light source is controllable or adjustable. The control unit may be configured to control operation of the at least two first light sources, respectively, (for example, by individually controlling operation of the respective first light sources) at least with respect to the controlling or adjusting of the intensity pattern of the light emitted by each of the at least two first light sources, such that the intensity patterns of the light emitted by the respective ones of the at least two first light sources are different. By controlling or adjusting of the intensity pattern of the light emitted by each of the at least two first light sources, such that the intensity patterns of the light emitted by the respective ones of the at least two first light sources are different, a variety of dynamic lighting effects can be obtained on a surface of an object that is illuminated by the lighting device.

The control unit may be configured to run computer-executable instructions (e.g., a computer program) which when run or executed in the control unit causes the control unit to control operation of any component of the lighting device which the control unit may be configured to control operation of, such as, for example, the at least one first light source, such as described in the foregoing.

The at least one first light source may for example comprise a laser (e.g., comprising one or more laser diodes). The intensity pattern may for example comprise a laser pattern, such as, for example, a speckle pattern. The at least one second light source may for example include or be constituted by a solid state light emitter. Examples of solid state light emitters include inorganic LEDs, organic LEDs, and light conversion elements such as phosphor plates, Lumiramic plates or phosphor conversion crystals. For example, the at least one second light source may encompass a bare LED die arranged in a housing, which may be referred to as a LED package.

The at least one second light source may for example comprise at least one LED light source. The at least one LED light source may for example comprise a white LED and/or an RGB LED light source.

The lighting device may comprise at least one optical element which may be arranged so as to receive at least a portion of the light emitted by the at least one second light source and output optically modified light. The optical element may for example comprise a total internal reflection collimator and/or a reflector.

The first wavelength range may comprise wavelengths shorter than or equal to about 440 nm. The first wavelength range may for example be about 400 nm to about 440 nm. Light in a wavelength range between about 400 nm and about 440 nm may for example be produced by means of light having a narrow emission spectrum with a full width half maximum (FWHM) of less than 50 nm, such as less than 20 nm, and for example (about) 15 nm. For example in case the at least one first light source comprises a laser diode, the FWHM may be less than 5 nm, such as (about) 1 nm. Light in a wavelength range between about 400 nm and about 440 nm may for example be produced by means combining multiple light sources having different peak wavelengths in their output light, for example by combining a laser diode which is configured to emit light at a wavelength of (about) 420 nm and a laser diode which is configured to emit light at a wavelength of (about) 430 nm.

The second wavelength range may comprise wavelengths longer than about

440 nm. The second wavelength range may for example be about 440 nm to about 800 nm. The second wavelength range may include wavelengths in the blue, green-yellow, and orange-red wavelength ranges. The second wavelength range may be produced using a light source provided with at least one broadband wavelength material. The at least one broadband wavelength material may for example comprise any wavelength converting material as known in the art, having an emission spectrum with a FWHM of 50 nm or more, for example (about) 90 nm. Hence, the term "broadband" refers to the bandwidth of the emission spectrum of the wavelength converting material(s). Light emitted by the at least one first light source may have an emission peak within the first wavelength range. Light emitted by the at least one second light source may have an emission peak within the second wavelength range. The emission peak within the first wavelength range may be a shorter wavelength or wavelengths as compared to the emission peak within the second wavelength range.

The at least one first light source and/or the at least one second light source may be arranged and/or configured such that a predefined fraction of the light output by the lighting device is in the first wavelength range or in the second wavelength range, possibly with the remainder of the light output by the lighting device being in the other one of the first wavelength range or the second wavelength range. For example, (about) 80% or more of the light output by the lighting device may be in the first wavelength range.

The lighting device may comprise at least two first light sources. At least two of the first light sources may be configured to emit light when operated within different first wavelength ranges. Two of the first light sources may for example comprise lasers, or laser diodes. One laser or laser diode may be configured to emit light at - or with the emission spectrum having a peak at - a wavelength of (about) 405 nm, and the other or another laser or laser diode may be configured to emit light at - or with the emission spectrum having a peak at - a wavelength of (about) 430 nm.

According to a second aspect of the present invention a lamp or luminaire is provided. The lamp or luminaire comprises a lighting device according to the first aspect.

The lamp or luminaire may for example be comprised, mounted or arranged with respect to a shelf, rack or stand so as to illuminate products or articles for example in a shop.

Photo-luminescent material should, in the context of the present application, be understood as any material that is capable of light emission from the material after its absorption of photons. Examples of photo-luminescent materials which may be used in conjunction with embodiments of the present invention may for example include at least one phosphor or a mixture or aggregate of several different phosphors, and/or quantum

confinement structures. The term "quantum confinement structures" should, in the context of the present application, be understood as e.g. quantum wells, quantum dots, quantum rods, or nano-wires. A quantum well is a potential well with only discrete energy values and may be formed in semiconductors by having a material, like gallium arsenide or indium gallium nitride sandwiched between two layers of a material with a wider band gap, like aluminum arsenide or gallium nitride. Quantum dots (or rods, or nano-wires) are small crystals of semiconducting material generally having a size, e.g. width, radius or diameter, of only a few nanometers. When excited by incident light, a quantum dot emits light of a color determined by the size and material of the crystal. Light of a particular color can therefore be produced by adapting the size and/or material of the quantum dots.

Further objects and advantages of the present invention are described in the following by means of exemplifying embodiments. It is noted that the present invention relates to all possible combinations of features recited in the claims. Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the description herein. Those skilled in the art realize that different features of the present invention can be combined to create embodiments other than those described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplifying embodiments of the invention will be described below with reference to the accompanying drawings.

Fig. 1 is a schematic view of a lighting device according to an embodiment of the present invention.

Fig. 2 is a schematic graph of intensity versus wavelength for an example of white light having a wavelength within a wavelength range from 440 nm to 800 nm.

Fig. 3 is a schematic graph of intensity versus wavelength for an example of 'crispy white' light.

Figs. 4 to 6 are schematic graphs indicating the intensity pattern of the light emitted by the at least one first light source in accordance with embodiments of the present invention.

Figs. 7 to 9 are schematic views of lighting devices according to embodiments of the present invention.

Fig. 10 is a schematic view of a lamp according to an exemplifying embodiment of the present invention.

Fig. 1 1 is a schematic view of a luminaire according to an exemplifying embodiment of the present invention.

All the figures are schematic, not necessarily to scale, and generally only show parts which are necessary in order to elucidate embodiments of the present invention, wherein other parts may be omitted or merely suggested.

DETAILED DESCRIPTION The present invention will now be described hereinafter with reference to the accompanying drawings, in which exemplifying embodiments of the present invention are shown. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments of the present invention set forth herein; rather, these embodiments of the present invention are provided by way of example so that this disclosure will convey the scope of the invention to those skilled in the art. In the drawings, identical reference numerals denote the same or similar components having a same or similar function, unless specifically stated otherwise.

Figure 1 is a very schematic view of a lighting device 100 according to an embodiment of the present invention. The lighting device 100 comprises a first light source 1 10 which is configured to emit light when operated. The first light source 1 10 is configured to emit light 1 15 within a first wavelength range. The lighting device 100 comprises a second light source 120 which is configured to emit light 125 when operated. The second light source 120 is configured to emit light within a second wavelength range, which is different from the first wavelength range. The first wavelength range includes shorter wavelengths as compared to the second wavelength range. The first wavelength range may for example have an emission peak at a shorter wavelength as compared to an emission peak of the second wavelength range. The first wavelength range and the second wavelength range may be non- overlapping, or there may be some overlap between them. Although not illustrated in Figure 1 , the lighting device 100 may comprise a light output or light exit, such as a light exit window, through which both light 1 15 emitted by the first light source 1 10 and light 125 emitted by the second light source 120 may exit or be output from the lighting device 100. The lighting device 100 is configured to emit a combination of light 1 15 emitted by the first light source 1 10 and light 125 emitted by the second light source 120 when the first light source 1 10 and the second light source 120, respectively, are operated, such that light emitted by the lighting device 100 (e.g., in the far field) comprises wavelengths included in the first wavelength range and in the second wavelength range. The first light source 1 10 is configured such that the intensity of the light emitted by the first light source 1 10 spatially varies according to an intensity pattern, e.g. in the far field of the first light source 1 10. The first light source 1 10 may for example emit white light having a wavelength within a wavelength range from 440 nm to 800 nm, and the second light source 120 may for example emit a short wavelength blue light having a wavelength within a wavelength range from 400 nm to 440 nm. The first light source 1 10 may for example comprise a laser light source, and the second light source 120 may for example comprise a LED-based light source, by which a spatially patterned light having a relatively high spatial resolution may be produced for a patterned appearance on a surface of an object in the far field (not shown in Figure 1) illuminated by the lighting device 100. By superimposing or combining a pattern of a short wavelength blue light, for example having a wavelength within a wavelength range from 400 nm to 440 nm, on or with white light, for example having a wavelength within a wavelength range from 440 nm to 800 nm, the lighting device 100 may be capable of emitting light exhibiting a 'crisp white light' effect. The (possibly white) light from the second light source 120 may be non-patterned light. That is, the light emitted by the second light source 120 may not be spatially patterned light but may exhibit a spatially uniform intensity. In order to produce patterned light 1 15 emitted by the first light source 1 10, optical elements such as diffractive and/or refractive elements, masks or lenses - which as such are known in the art - may for example be used.

The light source 1 10 may for example comprise a laser or a LED light source or the combination thereof. At least one of the laser and the LED light source may be configured so that the light 1 15 is patterned light.

Figure 2 is a schematic graph of the intensity I (in an arbitrary unit) versus the wavelength (in nm) for an example of white light having a wavelength within a wavelength range from 440 nm to 800 nm. Figure 3 is a schematic graph of the intensity I (in an arbitrary unit) versus the wavelength (in nm) for an example of 'crispy white' light wherein an addition of short wavelength blue light having a wavelength within a wavelength range from 400 nm to 440 nm to the white light illustrated in Figure 2 is allowed to form part of the total output spectrum.

With further reference to Figure 1, the lighting device 100 may comprise an optical element 130 arranged so as to receive at least a portion of the light emitted by the first light source 1 10 and modify or manipulate the light received by the optical element 130. Thus, at least a portion of the light output by the first light source 1 10 may prior to being emitted by the lighting device 100 be modified at the optical element 130 so that emitted light 1 15 is optically modified as compared to light emitted by the first light source 1 10 prior to having been received by the optical element 130. It is to be understood that the optical element 130 is optional. The optical element 130 may for example comprise a diffractive optical element, a refractive optical element, a diffusive optical element and/or a switchable optical element. The optical element 130 may be removably or releasably arranged in the lighting device 100. The first light source 1 10 may, as mentioned in the foregoing, for example comprise a laser light source, which for example may include or be constituted by a laser diode. The laser light source or laser diode may comprise a collimator such as a lens or the like for collimating the laser light into collimated light. The collimated light may

subsequently be redirected by the optical element 130. Laser light that is spatially patterned (e.g., in the far field) may be achieved with or with or without an optical element (such as the optical element 130) since a laser light source is generally capable of producing a speckle pattern in the far field.

It should be understood that Figure 1 is a very schematic view of a lighting device 100 and only illustrates parts which are necessary in order to elucidate embodiments of the present invention, whereas other parts which may possibly be included in the lighting device 100 are omitted in Figure 1. Such other parts may for example comprise a power supply and/or electrical wiring or conductors, driver circuitry, a housing, fixation

arrangements for the different components in the lighting device 100, etc. Such other possible parts are hence omitted in Figure 1. The same considerations also apply to each of the lighting devices 100 illustrated in Figures 7 to 9, which are described further in the following.

In the context of the present application, by the first light source 1 10 being configured such that the intensity of the light emitted by the first light source 1 10 spatially varies (e.g., in the far field) according to an intensity pattern, it is meant that the light emitted by the first light source 1 10 comprises spatially patterned light, for example such that a beam of light from the first light source 1 10 incident on a surface of an illuminated object (not shown in Figure 1) does not exhibit a spatially uniform intensity but has a varying intensity pattern over the portion of the illuminated surface. The intensity pattern of the light emitted by the first light source 1 10 may for example be a predefined or a selected intensity pattern. The first light source 1 10 may be configured such that the intensity pattern is controllable, or adjustable. To that end, the first light source 1 10 may for example comprise a laser (e.g., comprising one or more laser diodes). Figures 4 to 6 are schematic graphs which indicate examples of the intensity pattern of the light which may be emitted by the first light source 1 10 in accordance with embodiments of the present invention. The graphs in Figures 4 to 6 schematically illustrate examples of how the intensity I (in an arbitrary unit) of the light which may be emitted by the first light source 1 10 may vary along an axis x (in an arbitrary unit) for example on an illuminated surface of an object that is illuminated by the first light source 1 10. It is to be understood that Figures 4 to 6 illustrate non-limiting examples of the intensity pattern of the light which may be emitted by the first light source 1 10 in accordance with embodiments of the present invention, and that other intensity patterns are possible.

As indicated in Figures 4 to 6, the intensity of the light which may be emitted by the first light source 1 10 may vary along an axis x on or across an illuminated surface of an object that is illuminated by the first light source 1 10 so that the intensity has a series of alternating 'dips' and 'peaks', possibly such that the intensity for example has more than four peaks along the axis x, or preferably more than ten peaks along the axis x, or most preferably more than twenty peaks along the axis x.

Figure 7 is a very schematic view of a lighting device 100 according to another embodiment of the present invention. The lighting device 100 illustrated in Figure 7 is similar to the lighting device 100 illustrated in Figure 1 , and identical reference numerals in Figures 1 and 7 denote the same or similar components having the same or similar function. The lighting device 100 illustrated in Figure 7 differs from the lighting device 100 illustrated in Figure 1 in that the lighting device 100 illustrated in Figure 7 in addition to a first optical element 130 comprises an additional, second optical element 140 which is arranged so as to receive at least a portion of the light which has been emitted by the first light source 1 10 and modified or manipulated by the first optical element 130. The second optical element 140 is arranged to modify the light received by the second optical element 140. Thus, at least a portion of the light output by the first light source 1 10 may prior to being emitted by the lighting device 100 be modified at both the first optical element 130 and the second optical element 140 so that emitted light 1 15 is optically modified as compared to light emitted by the first light source 1 10 prior to having been received by the first optical element 130 and the second optical element 140. It is to be understood that both the first optical element 130 and the second optical element 140 are optional. As indicated in Figure 7, the second optical element 140 may for example comprise a collimating or focusing optical element such as a collimator or a lens. The second optical element 140 may be removably or releasably arranged in the lighting device 100.

In alternative or in addition the second optical element 140 may be arranged so as to receive at least a portion of the light which has been emitted by the second light source 120 and modify or manipulate the received light.

Figure 8 is a very schematic view of a lighting device 100 according to another embodiment of the present invention. The lighting device 100 illustrated in Figure 8 is similar to the lighting device 100 illustrated in Figure 1 , and identical reference numerals in Figures 1 and 8 denote the same or similar components having the same or similar function. The lighting device 100 illustrated in Figure 8 comprises a sensor 150, which may be configured to sense presence of at least one person in a region surrounding the lighting device 100. The sensor 150 may for example comprise a presence or motion sensor, such as, for example, a passive infrared detector, an ultrasonic motion detector, or a camera-based sensor. The lighting device 100 illustrated in Figure 8 comprises a control unit 160. The control unit 160 is communicatively coupled to at least the sensor 150 and the first light source 1 10. The communicative coupling between the control unit 160 and the sensor 150, and between the control unit 160 and the first light source 1 10, respectively, may for example be achieved or implemented by way of any wired and/or wireless communication technique or communication means as known in the art. The control unit 160 may be configured to control operation of the first light source 1 10 (at least with respect to switching on and off the first light source 1 10) based on information regarding presence of any person(s) in the region obtained by the sensor 150 when carrying out the sensing (operation).

Light having relatively short wavelengths may not always be desirable because it may under certain circumstances harm the eyes of a person looking into the light. Therefore, when or whenever a person is relatively close to the lighting device 100 the first light source 1 10 may be switched off so that it does not emit light. To that end, the control unit 160 may be configured to, on a condition that the presence of at least one person within a selected distance from the lighting device 100 (or for example from the sensor 160 or the first light source 1 10) is sensed by the sensor 150, control operation of the first light source 1 10 such that it does not emit light, and otherwise control operation of the first light source 1 10 such that it emits light. Thereby, the first light source 1 10 may emit light only when there is no person within a selected distance from the lighting device 100.

Light having relatively short wavelengths may damage certain products when illuminated during an extended period of time. To that end, the control unit 160 may in alternative be configured to, on a condition that the presence of at least one person within a selected distance from the lighting device 100 (or for example from the sensor 150 or the first light source 1 10) is sensed by the sensor 150, control operation of the first light source 1 10 such that it emits light, and otherwise control operation of the first light source 1 10 such that it does not emit light. Thereby, the first light source 1 10 may emit light only when there is a person within a selected distance from the lighting device 100.

The sensor 150 and the control unit 160 are both optional.

Figure 9 is a very schematic view of a lighting device 100 according to another embodiment of the present invention. The lighting device 100 illustrated in Figure 9 is similar to the lighting device 100 illustrated in Figure 1 , and identical reference numerals in Figures 1 and 9 denote the same or similar components having the same or similar function. The lighting device 100 illustrated in Figure 9 comprises two first light sources 1 10 and 170. The first light source 1 10 and the first light source 170 may be configured to emit light when operated within different (but possibly overlapping) first wavelength ranges. The first light source 170 is configured such that the intensity of the light 175 emitted by the first light source 170 spatially varies (e.g., in the far field) according to an intensity pattern, possibly similarly to the first light source 1 10 such as described in the foregoing. Each of the two first light sources 1 10 and 170 is configured such that the intensity pattern of the light 1 15, 175 emitted by each of the two first light sources 1 10 and 170 is controllable. Similarly to the lighting device 100 illustrated in Figure 8, the lighting device 100 illustrated in Figure 9 comprises a control unit 160. The control unit 160 is communicatively coupled to at least the first light sources 1 10 and 170. The communicative coupling between the control unit 160 and the respective ones of the first light sources 1 10 and 170 may for example be achieved or implemented by way of any wired and/or wireless communication technique or

communication means as known in the art. The control unit 160 may be configured to control operation of the respective ones of the two first light sources 1 10 and 170, at least with respect to the controlling of the intensity pattern of the light emitted by each of the two first light sources 1 10 and 170, such that the intensity patterns of the light emitted by the respective ones of the two first light sources 1 10 and 170 are different. By controlling or adjusting of the intensity pattern of the light emitted by each of the two first light sources 1 10 and 170, such that the intensity patterns of the light emitted by the respective ones of the two first light sources 1 10 and 170 are different, a variety of dynamic lighting effects may be obtained on a surface of an object (not shown in Figure 9) that is illuminated by the lighting device 100.

Figure 10 is a schematic view of a lamp 200 according to an exemplifying embodiment of the present invention. The lamp 200 comprises a lighting device (not shown in Figure 10) according to an embodiment of the present invention. In accordance with the illustrated embodiment the lamp 200 comprises a so called "retrofit lamp" which is designed to have the appearance of a traditional incandescent light bulb and to be mounted in a conventional socket (e.g., an Edison screw base), with the light emitting filament wire being replaced with a lighting device according to an embodiment of the present invention.

Figure 1 1 is a schematic view of a luminaire 300 according to an exemplifying embodiment of the present invention. The luminaire 300 comprises at least one lighting device (not shown in Figure 1 1) according to an embodiment of the present invention. The light emitted by the luminaire 300 is indicated by the arrows in Figure 1 1. As indicated in Figure 1 1, the luminaire 300 is configured to be suspended for example from a ceiling (not shown in Figure 1 1) by way of suspension means such as wires 301, 302.

It is to be understood that Figures 10 and 1 1 illustrate non-limiting examples of applications for lighting devices according to embodiments of the present invention. Other applications are conceivable, such as, for example, wherein the lighting device, the lamp or the luminaire may be comprised, mounted or arranged with respect to a shelf, rack or stand so as to illuminate products or articles for example in a shop. For example, the lighting device might be embedded in or integrally arranged with different objects, e.g., a shelf for products in a shop, as indicated in the foregoing.

In conclusion a lighting device is disclosed, which lighting device comprises at least one first light source configured to emit light within a first wavelength range and at least one second light source configured to emit light when operated within a second wavelength range, wherein the second wavelength range is different from the first wavelength range and the first wavelength range includes shorter wavelengths as compared to the second wavelength range. The at least one first light source is configured such that the intensity of the light emitted by the at least one first light source spatially varies according to an intensity pattern.

While the present invention has been illustrated in the appended drawings and the foregoing description, such illustration is to be considered illustrative or exemplifying and not restrictive; the present invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the appended claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

CLAIMS:

1. A lighting device (100) comprising:

at least one first light source (1 10; 170) configured to emit light (1 15; 175) when operated within a first wavelength range; and

at least one second light source (120) configured to emit light (125) when operated within a second wavelength range, wherein the second wavelength range is different from the first wavelength range, and wherein the first wavelength range includes shorter wavelengths as compared to the second wavelength range;

wherein:

the lighting device is configured to emit a combination of light emitted by the at least one first light source and light emitted by the at least one second light source when the at least one first light source and the at least one second light source, respectively, are operated, such that light emitted by the lighting device comprises wavelengths included in the first wavelength range and in the second wavelength range;

the at least one first light source is configured such that the intensity of the light emitted by the at least one first light source spatially varies according to an intensity pattern; and

the at least one second light source is configured so that the light emitted by the at least one second light source exhibits a spatially uniform intensity.

2. A lighting device according to claim 1, wherein the first wavelength range comprises wavelengths shorter than or equal to about 440 nm, and the second wavelength range comprises wavelengths longer than or equal to about 440 nm.

3. A lighting device according to claim 1 or 2, further comprising at least one first optical element (130) arranged so as to receive at least a portion of the light emitted by the at least one first light source and to modify the received light, wherein the at least one first optical element comprises at least one of: at least one diffractive optical element, at least one refractive optical element, at least one diffusive optical element, or at least one switchable optical element.

4. A lighting device according to claim 3, wherein the first optical element is removably arranged in the lighting device.

5. A lighting device according to claim 3 or 4, further comprising at least one second optical element (140) arranged so as to receive at least a portion of the light emitted by at least one of the at least one first light source or the at least one second light source and to modify the received light, wherein the at least one second optical element comprises a collimating and/or focusing optical element.

6. A lighting device according to claim 5, wherein the second optical element is removably arranged in the lighting device.

7. A lighting device according to any one of claims 1-6, further comprising:

at least one sensor (150) configured to sense presence of at least one person in a region surrounding the lighting device; and

a control unit (160) communicatively coupled to at least the at least one sensor and the at least one first light source, the control unit being configured to control operation of the at least one first light source based on information regarding presence of any person(s) in the region obtained by the at least one sensor when carrying out the sensing;

the control unit being configured to, on a condition that the presence of at least one person within a selected distance from the lighting device is sensed by the at least one sensor, control operation of the at least one first light source such that it does not emit light, and otherwise control operation of the at least one first light source such that it emits light.

8. A lighting device according to any one of claims 1-6, further comprising:

the control unit being configured to, on a condition that the presence of at least one person within a selected distance from the at least one sensor or the at least one first light source is sensed by the at least one sensor, control operation of the at least one first light source such that it emits light, and otherwise control operation of the at least one first light source such that it does not emit light.

5 9. A lighting device according to any one of claims 1-8, wherein the at least one first light source is configured such that the intensity pattern is controllable, and wherein the lighting device further comprises a control unit (160) communicatively coupled to at least the at least one first light source, the control unit being configured to control operation of the at least one first light source at least with respect to the controlling of the intensity pattern of the 10 light emitted by the at least one first light source.

10. A lighting device according to claim 9, comprising at least two first light sources (1 10, 170), wherein each of the at least two first light sources is configured such that the intensity pattern of the light (1 15, 175) emitted by the first light source is controllable, 15 wherein the control unit is configured to control operation of the at least two first light

sources, respectively, at least with respect to the controlling of the intensity pattern of the light emitted by each of the at least two first light sources such that the intensity patterns of the light emitted by the respective ones of the at least two first light sources are different.

20 1 1. A lighting device according to any one of claims 1 -10, wherein the at least one first light source comprises at least one laser.

12. A lighting device according to claim 1 1, wherein the intensity pattern comprises a laser pattern.

25

13. A lighting device according to claim 12, wherein the laser pattern is a speckle pattern.

14. A lighting device according to any one of claims 1 -13, comprising at least two

30 first light sources (1 10, 170), wherein at least two of the first light sources are configured to emit light when operated within different first wavelength ranges.

15. A lamp (200) or luminaire (300) comprising a lighting device (100) according to any one of claims 1-14.